AQUEOUS METAL TREATMENT COMPOSITION
Relation Back
This application claims benefit of U.S. provisional application serial number
60/072,782, filed January 27, 1998, and is a continuation-in-part of application serial
number 09/235,201 filed January 22, 1999 (now allowed).
Background
The present invention relates to an aqueous autodepositable composition that is
useful as a metal surface treatment.
It is well-known that metal surfaces are subject to corrosive and chemical
degradation. This degradation has been combated by the application of various
treatments to the metal surface. Conversion coating of the metal surface is one such
treatment. Conversion coating generally involves treating the surface with chemicals that
form a metal phosphate and/or metal oxide conversion coating on the metal surface. The
conversion coating provides protection against corrosion and can enhance adhesion of
any subsequent coatings. Phosphatizing is a well-established conversion process.
However, phosphatizing suffers from several drawbacks. It is a complex multistcp
process that is capital intensive, requires close monitoring and can generate significant
amounts of waste sludge. In addition, phosphatizing requires oxidative accelerators that
promote corrosion and thus must be removed by multiple rinsing steps. Conventional
inorganic phosphate conversion coatings are also very brittle and thus can fracture. A
seal coat also is typically applied for good corrosion resistance that often includes
hexavalent chrome which presents considerable environmental problems.
It is also generally known that the corrosion resistance of metal substrates can be
improved by coating the substrate with an autodeposition composition that generally
comprise an aqueous solution of an acid, an oxidizing agent and a dispersed resin.
Immersion of a metallic surface in an autodeposition composition produces what is said
to be a self-limiting protective coating on a metal substrate. The general principles and
advantages of autodeposition are explained in a multitude of patents assigned to Parker
Amchem and/or Henkel (see, for example, U.S. Patents No. 4,414,350; 4,994,521;
5,427,863; 5,061,523 and 5,500,460).
U.S. Patent No. 5,691,048 includes phosphoric acid in a list for possible acids in
an autodepositing composition, but hydrofluoric acid is the preferred acid. This patent
also lists hydrogen peroxide, chromic acid, potassium dichromate, nitric acid, sodium
nitrate, sodium persulfate, ammonium persulfate, sodium perborate and ferric fluoride as
possible oxidizing agents. Hydrogen peroxide and ferric fluoride are preferred.
Phosphatizing is also a well-known conversion treatment for providing corrosion
resistance to metal surfaces. U.S. Patent No. 5,011,551 relates to a metal conversion
coating composition that includes an aliphatic alcohol, phosphoric acid, an alkali nitrate,
tannic acid and zinc nitrate. U.S. Patent No. 4,293,349 relates to a steel surface
protective coating composition that includes pyrogallic acid glucoside, phosphoric acid,
phosphates of bivalent transition metals such as Zn or Mn, Zn or Mn nitrate, and,
optionally, formaldehyde.
An environmentally acceptable, user-friendly metal treatment with superior
corrosion resistance and fracture toughness would be very desirable.
Summary
An aqueous metal surface treatment composition comprising the following
ingredients:
(A) an aqueous dispersion of a phenolic resin that includes a reaction product of
(i) a phenolic resin precursor;
(ii) a modifying agent, comprising a hydrocarbyl moiety bonded to
at least one functional moiety that enables the modifying agent to react
with the phenolic resin precursor; and at least one ionic moiety comprising an lonizable
group containing sulfur or phosphorous,
(iii) at least one multi-hydroxyphenolic compound; and
(B) optionally an acid, wherein (iii) is optional in (A) when said reaction
product (A) contains two or more reactive phenolic methylol groups.
In an autodepositable metal treatment, the aqueous dispersion comprises a (1) phenolic
novolak resin and (2) a reaction product in which a phenolic resin precursor is reacted
with a modifying agent that includes at least one functional moiety that enables the
modifying agent to react with the phenolic resin precursor and at least one ionic moiety,
(3) optionally an acid and, optionally, (4) a flexibilizer. According to one embodiment
the modifying agent comprises an aromatic hydrocarbyl moiety. According to another
embodiment, the ionic moiety of the modifying agent is sulfonate, sulfinate, or sulfenate
group, and the dispersed phenolic resin reaction product has a carbon/sulfur atom ratio
preferably from 20:1 to 200:1.
The phosphorous ionic moieties of the modifying agent comprise a
phosphorous-containing goup, including, for example, phosphono, -P(0)(OH)2;
phosphono ester -P(0)(OH)(OR); phosphonomethyl ,-CH2P(0)(OH)2; phosphino,
-P(0)(OH); and phosphinomethyl, -CH2P(0)(OH) .
In still further embodiments, the ionic moiety of the modifying agent comprises
an activated carboxylic acid group. An activated carboxylic group contains ct,oc-halo
substitution and the acid is sufficiently ionized to result in a stable dispersion over the pH
range of 1-3, typically encountered in a autodepostion metal treatment, as taught herein.
The metal treatment composition preferably is applied to electrochemically active
metals such as steel. This treatment improves adhesion of subsequent coalings such as
primers and adhesives to the metal surface and it improves corrosion resistance. Since
this treatment requires only a minimum number of coatings - typically less than three and
often only a single coating - it is much more user friendly than conventional
phosphatizing and eliminates the need for a seal coat. In addition, the metal treatment
generally does not require any rinsing steps subsequent to application of the metal
treatment composition. A unique feature of the invention is that the metal treatment
composition is autodepositable.
It has also been discovered that metal substrates treated with the compositions
of this invention may require sitting at ambient conditions (approximately 25°C) for an
extended time period after autodepositing and drying (approximately 2 to 24 hours after
drying) and prior to application of a subsequent coating of a different composition. This
intermediate time period is referred to herein as the "ambient staging period". Without
this ambient staging period the corrosion resistance of the final product was inconsistent
for certain demanding commercial applications. In addition, formation of a uniformly
thick metal treatment coating is required for superior corrosion resistance. Too thin or
too thick a coating also can be detrimental to corrosion protection.
Addition of a control agent to autodeposition compositions has been found to .
dramatically improve uniform coating formation on more complex surface topography
and enhance the autodeposition of subsequently-applied compositions thus improving
corrosion resistance and overall robustness. The protective coating formed by the
composition of the invention is particularly useful for providing corrosion resistance to
metal substrates that are subjected to significant stresses and/or strains causing significant
flexing or movement of the substrate surface. Due to the improved deposition caused by
the control agent, the concentration of active ingredients in an autodepositable
composition that includes the control agent can be reduced. Another advantage of the
invention is that there is no need to post-rinse the treated surface in order to remove any
control agent residue. Furthermore, the control agent eliminates or substantially
eliminates the ambient staging period thus improving process efficiency.
Accordingly, a further embodiment of the invention provides an aqueous
autodeposition composition that includes an autodepositable component and a control
agent, preferably an organic nitro material. The autodepositable component preferably is
an aqueous phenolic resin dispersion, particularly the aqueous novolak dispersion
mentioned above. The autodeposition composition is particularly useful as a metal
treatment composition that also includes an acid, especially phosphoric acid.
According to another embodiment of the invention there is provided a method
for treating a metal surface that includes applying to the surface an aqueous
autodeposition composition that includes an autodepositable component and the control
agent.
Detailed Description
Unless otherwise indicated, description of components in chemical nomenclature
refers to the components at the time of addition to any combination specified in the
description, but does not necessarily preclude chemical interactions among the
components of a mixture once mixed.
Certain terms used in this document are defined below.
"Primer" means a liquid composition applied to a surface as an undercoat
beneath a subsequently-applied covercoat. The covercoat can be an adhesive and the
primer/adhesive covercoat forms an adhesive system for bonding two substrates together.
"Coating" means a liquid composition applied to a surface to form a protective
and/or aesthetically pleasing coating on the surface.
"Phenolic compound" means a compound that includes at least one hydroxy
functional group attached to a carbon atom of an aromatic ring. Illustrative phenolic
compounds include unsubstituted phenol per se, substituted phenols such as alkylated,
alkoxy-phenols, chloro-phenols, and multi-hydroxy phenols, and hydroxy-substituted
multi-ring aromatics, e.g. phenolic novolak, and phenolic resoles. Illustrative alkylated
phenols include methylphenol (also known as cresol), dimethylphenol (also known as
xylenol), 2-ethylphenol, pentylphenol and teit-butyl phenol. "Multi-hydroxy phenolic
compound" means a compound that includes more than one hydroxy group on each
aromatic ring. Illustrative multi-hydroxy phenols include 1,3-benzenediol (also known as
resorcinol), 1,2-benzenediol (also known as pyrooatechol), 1,4-benzencdiol (also known
as hydroquinone), 1,2,3-benzenetriol (also known as pyrogallol), 1,3,5-benzenetriol and
4-tert-butyl-l,2-benzenediol (also known as tert-butyl catechol). Illustrative hydroxy-
subslituted multi-ring aromatics include 4,4'-isopropylidenebisphenol (also known as
bisphenol A), 4,4'methy]idenebisphenol (also known as bisphenol F) and naphthol.
"Aldehyde compound" means a compound having the generic formula RCHO.
Illustrative aldehyde compounds include formaldehyde, acetaldehyde, propionaldehyde,
n-butylaldehyde, n-valeraldehyde, caproaldehyde, heptaldehyde and other straight-chain
aldehydes having up to 8 carbon atoms, as well as compounds that decompose to
formaldehyde such as paraformaldehyde, trioxane, furfural, hexamethylenetriamine,
acetals that liberate formaldehyde on heating, and benzaldehyde.
"Phenolic resin" generally means the reaction product of a phenolic compound
with an aldehyde compound. The molar ratio of the aldehyde compound (for example,
formaldehyde) reacted with the phenolic compound is referred to herein as the "F/P
ratio". The F/P ratio is calculated on a per hydroxy-substituted aromatic ring basis.
"Phenolic resin precursor" means an unmodified or conventional phenolic resin
that is reacted with the modifying agent to produce the phenolic resin that is dispersed in
an aqueous phase.
"Electrochemically active metals" means iron and all metals and alloys more
active than hydrogen in the electromotive series. Examples of electrochemically active
metal surfaces include zinc, iron, aluminum and cold-rolled, polished, pickled, hot-rolled
and galvanized steel.
"Ferrous" means iron and alloys of iron.
The term "hydrocarbyl moiety" refers to an organic moiety which is aromatic, aliphatic or
a combination of aromatic and aliphatic moieties, and optionally containing O, N, S
and/or P as a substituents, or components intervening in the parent chain or backbone of
the structure.
The term "aryl" when used alone refers to an aromatic radical or group, whether or not
fused. Exemplary aryl groups include phenyl, naphthyl, biphenyl, and the like.
"Heteroaromatic" groups include, but are not limited to, furanyl, pyrrolyl, thienyl,
pyrazolyl, thiazolyl, oxazoly], pyridyl, pyrimidinyl, indolyl, and the like.
The term "substituted aryl" denotes an aryl or heteroaryl group substituted in any one (e.g.
1, 2, 3, 4, 5, etc.) or more available sites on a ring, and include independently chosen
substituents, such as halogen, cyano, nitro, d -Cio alkyl, d -do alkylol, d-do-
alkyloxy, Ci-do-oxya]kyl, d-Cio-carboxylic acid, d -do sulfonic acid, d-do-
carboxylic ester, d-do-caboxylic amide, trifluoromethyl, alkyloxycarbonyl, and the
like. Examples of such groups are 4-chloropheny], 2-methylphenyl, 3-ethoxyphenyl, and
orthomethylol.
The term "arylalkyl" means one or more aryl groups having a designated number of
carbons, substituted on a hydrocarbyl radical or moiety. Exemplary arylalkyl groups are
CVC30 aryl substituents on a CrC2o or d-Cio alkyl radical. An exemplary arylalkyl
group is a benzyl group, tolyl group, xylyl group, and a 2-ethylhexyl phenyl.
The term "alkenyl" refers to a straight or branched chain group of from two to ten carbon
atoms containing a carbon-carbon double bond, including, but not limited to allyl, vinyl,
and the like.
While not wishing to be bound to any particular theory, it is believed that the
metal treatment of this invention is based on the principle of autodcposition.
Autodeposition is useful in the control of film thickness. In some embodiments, effective
metal treatment is provided by contacting a metal surface without autodeposition, leaving
an effective metal treatment composition upon removal of water. When the treatment
composition is applied to an electrochemically active metal in an acidic autodepositable
preparation, the acid reacts with the metal to form multivalent ions (for example, ferric
and/or ferrous ions in the case of steel) that appear to cause the rate of deposition on the
metal surface lo be self-limiting, i.e., rate decreasing over time, to leave a substantially
uniform, gelatinous, highly acidic wet film. As the film dries (the drying can be
accelerated by heating) the remaining phosphoric acid converts the surface to the
respective metal compound with the respective negative ion of the acid (for example,
metal phosphate in the case of phosphoric acid) forming an interpenetrating network with
chelating groups of the aqueous dispersed phenolic novolak resin (A). The coating that is
formed when the composition is in contact with the metal surface is known as the
"unconverted" state. The subsequent drying of the coating converts the coating to a
"converted" state. The formation of the coating is substantially "self-limiting" in that the
coating increases in thickness and areal density (mass per unit area) the longer the time
the metallic substrate is immersed in the metal treatment composition. The rate of
thickness and areal density increase, however, decreases rapidly with immersion time.
The autodeposition characteristic of the invention is important to provide
corrosion resistance. It allows for the formation of an exceptionally uniform film.
Excellent corrosion resistance is possible only if the entire surface of a metal part is
protected with a barrier coating. This requirement is usually difficult to achieve on
substrate surfaces that have very complex topology. With the superior autodeposition of
this invention, wetting and thus protection of such complex surfaces is achieved. A
further advantage of the metal treatment is that it can activate a metal surface for
autodeposition of a subsequently applied coating or primer that includes a dispersed
phenolic resin as described above. Such a primer is described in more detail in
commonly-owned U.S. Patent Application Ser. No. 09/235,778 filed January 22. 1999,
entitled "Aqueous Primer or Coating".
Another important advantage of the metal treatment composition is that a bath of
the composition does not appear to change in composition as cumulative metal surfaces
are dipped in the bath over a period of time. It is believed that since the very hydrophilic
phenolic resin dispersion immobilizes or coagulates on the metal surface as a swollen wet
gel rather than as a precipitate, the composition of the bath is the same as the deposited
wet gel and the bath is not depleted. In addition, it appears that there is substantially no
build-up of ferrous/ferric ions in the bath.
In one embodiment the metal treatment composition contains an aqueous
dispersed modified phenolic novolak resin (A). In other embodiments the dispersed
phenolic is a modified resole, as illustrated below. The modified phenolic resole contains
one or more sulfonomethyl groups, and one or more methylol groups attached to the same
aromatic ring. These copending methylol groups are deactivated and this resole forms a
stable acidic dispersion and will cure on application of heat. The modified phenolic
novolak, or resole, or combinations thereof, or each or both in combination with other
phenolic resins are responsible for the autodeposition characteristic of the metal treatment
composition. The phenolic novolak resin dispersion (A) of the inventive composition can
be obtained by initially reacting or mixing a phenolic resin precursor and a modifying
agent - theoretically via a condensation reaction between the phenolic resin precursor and
the modifying agent. It should be recognized that conventional resole resins cannot be
used in or formulated into die metal treatment composition due to the presence of the
acid. Under the acidic conditions of the metal treatment conventional resoles are unstable
and can advance quickly to gellation at which point the system cannot form a film. The
parasulfonomethyl resole embodiments according to the invention are surprisingly stable
under acidic conditions.
One functional moiety of the modifying agent provides the ionic pendant group
that enables stable dispersion of the phenolic resin. Since the ionic pendant group
provides for the stability of the dispersion there is no need, or at the most a minimal need,
for surfactants. The presence of surfactants in an aqueous composition is a well-known
hindrance to the composition's performance.
The other important functional moiety in the modifying agent enables the
modifying agent to react with the phenolic resin precursor. The modifying agent can
contain more than one ionic pendant group and more than one reaction-enabling moiety.
Incorporation of aromatic sulfonate functional moieties into the phenolic resin
structure via condensation is the preferred method of providing the ionic pendant groups.
Accordingly, one class of ionic moieties are substituents on an aromatic ring that include
a sulfur atom covalently or ionically bonded to a carbon atom of the aromatic ring.
Examples of covalently bound sulfur-containing substituents are the acid forms and salts,
e.g., sulfonate (-S(0)2H.) and salts (-S(0),OTVf), sulfinate (-S(O)OH) and salts (-S(O)O"
NT), and sulfenate (-SOH) and salts (-SOM1), wherein M can be any monovalent ion
such as Na\ Li+, K\ or NR'4 (wherein R' is independently, hydrogen or alky], e.g., CrC6
alkyl). Another example of a covalently bound substituent is sulfate ion.
Sulfonate is the preferred ionic group. Generally, the modifying agent should not include
or introduce any multivalent ions into the phenolic resin dispersion since it is expected
that the presence of multivalent ions would cause the phenolic resin to precipitate rather
than remain dispersed.
The modifying agent comprises a hydrocarbyl moiety that contains at least one
ionic moiety and at least one group reactive with an active hydrogen ortho or para to
phenolic OH, or reactive with a methylol group to form a bond with the phenolic resin
precursor. A reaction product of the modifying agent and phenolic precursor
includes self curing embodiments, and embodiments which are further
reacted with at least one multi-hydroxyphenolic compound. Metal treatments
comprising the reaction product of itself in the case of self-curing modifying
agents. The hydrocarbyl moiety can contain atoms other than C and H, as
substituents or as intervening groups, or a combination of substituent and
intervening groups. A general depiction of a modifying agent is represented in
the following figures where "ionic" is the ionic group specified herein, "link" is
a group that covalently bonds to a phenolic, and "x" denotes an oxygen-,
nitrogen-, sulfur-, or phosphorous-containing group as a substituent in Fig. A
or as an intervening group in Fig. B:

Not depicted above is the included alternative where both intervening and
substituents groups are present in the hydrocarbyl moiety. Representative X
groups are O, S, N, acyl-N, tertiary N-alkyl, ether, thioether, sulfoxide,
sulfone, phosphine, phosphine, oxide, ureido, alkylated ureido, amide, and
alkylated amide.
Intervening X groups can be repeating units, e.g. polyethers segments.
The hydrocarbyl moiety comprises either (i) a CrC2o linear or branched,
substituted and unsubstituted aliphatic hydrocarbon, preferably C7-C20 more
preferably C7-C12 aliphatic hydrocarbons, (ii)
C6-C18 mononuclear-, (iii) C12-
C30 multinuclear- and C10-C30 fused aromatic compounds.
The modifying agent includes, at least one ionizable sulfur, and/or phosphorous, and/or
activated carboxylic acid group, which is sufficiently ionizedto form a stable dispersion
at a acidic pH (1-7), especially in a pH of 1-3 when the metal treatment compositions are
desiredly applied to a metal surface by autodeposition.
The ionizable sulfur-containing ionic moieties include, for example, a group
bearing a sulfonyl (S02-), sulfinyl (-SO-), sulfonate, (-S(0)20'JVT), sulfinate (-S(O)'O'
M'), and sulfenate (-SOM*) groups. More particularly, it can be, for example, a
sulfonoalkyl group (-R-S(0)20"M+) wherein R represents a C,-Ci;, -alkyl or -alkylene
group, such as, for example, a sulfonomethyl group (-CH2-S(0)20 IVf), wherein M+
represents a monovalent ion such as, for example, sodium, lithium, potassium, or
ammonium. Unless otherwise indicated in this disclosure, one skilled in the art
understands that the monovalent ion can be converted between different metals and the
acid, protonic form by ion exchange methods known in the art.
There are several known synthesis methods which can be utilized to make
compounds that are suitable modifying agents used in accordance with the present
invention. The modifying agent contains at least one ionic group, and at least one
reaction-enabling group reactive with a phenolic resin or phenolic resin precursor. One
example of a specific modifying agent is the sodium salt of 2,6-bis-(hydroxymethyl)-4-
sulfonomethyl-phenol (BHSP). This monomer is also useful as a condensate, which is a
linear sulfonomethylphenol oligomer or polymer formed on heating as illustrated in
Figure 1.
In FIG.l, n equals any number of repeating units, and arbitrarily is from 1-50 in reference
to an oligomer, or n = 51-500 in reference to a "polymer". Oligomers are preferred. The
condensate is expected to comprise a distribution of oligomers of varying number of
repeating units, and is water-dispersible over a broad range of molecular weight.
The sulfonomethyi phenol oligomer is useful for formulating into an aqueous
autodcpositable dispersion. Alternatively, the sulfonomethyi phenol oligomer is useful by
itself as an aqueous metal treatment. This ionic stabilized resole is uniquely stable under
acidic conditions, and will cure on heating in combination with a phenolic, e.g.
rcsorcinol, or a novolak having multiple reactive sites. A condensate formed form the
reaction of the sulfonomethyi phenol oligomer and another phenolic having more than
one reactive site is self-curing, and is useful as a 1-coat metal treatment. The condensate
can be combined with a phenolic precursor, phenolic novolak, or phenolic which is
modified according to the present invention In but another embodiment, the linear
sulfonomethyi phenol monomer or oligomer is co-condensed with a phenolic precursor,
or a novolak resin and formulated into an autodepositable dispersion in accordance with
the invention. In yet another alternative embodiment the sulfonomethyi phenol monomer
or oligomer can be physically blended with a phenolic resin in an autodepositable
aqueous dispersion and upon deposition and subsequent heating, forms a co-condensate
with the phenolic resin.
Another exemplary method for preparing modifying agents having
sulfonomethyl groups is to react a phenolic compound having hydroxylmethyl groups (-
CH2OH) such as a phenolic resole with a sulfonomethylation agent such as, for example,
Na2S03 or NaHS03 as illustrated in Figure 2. Para substitutions are included.
Substitution of a sulfonomethylating agent at the ortho position is preferred.
Another example embodiment is the reaction of a novolak with either (i) a
sulfonomethylation agent such as, for example, Na+CH2S03~, or (ii) a sulfonomethylation
agent such as Na2S03 or NaHS03 in combination with an aldehyde source such as
formaldehyde as illustrated in Figure 3. Examples of a stalling phenolic include the
phenolic precursors, such as resorcinol, catechol, pyrogallol, phorglucinol, and carboxyl-,
carboxy ester-, and carboxy amide derivatives of phenolic precursors, which are
commonly available.
wherein Z = OH, H, phenolic, carboxyhc acid, carboxylic ester or carboxylic amide witli
the proviso that at least one active H remains ortho or para to a phenolic OH; and when
three sulfonomethyl groups are present on the ring, Z must be phenolic.
F1G.3
Still further, another example of a preparation for the modifying agent is to react
a methylolated sulfonomethyl compound such as, for example, a salt of BHSP with a
phenolic resin such as, for example, a novolak, as illustrated in Figure 4.
FIG. 4
In another example, the modifying agent also can be prepared starting from 4-
hydroxybenzylalcohol or 2,4,6-tri(hydroxymethyl)phenol or from sulfonomethylated
derivatives as illustrated in Figure 5 (showing TMP, 2,4,6-tri(hydroxyrnethyl)phenol).
This reaction can be carried out in water at reflux. The temperature of the reaction is an
important parameter. For example, using reflux conditions in water, the reaction is
completed within a few hours and one obtains a mix of ortho and para substituted
sulfonomethylphenols as shown in Figure 5. However, to obtain selective para-
sulfonomethylation of methylolated phenols like TMP, the temperature should be kept
below 60°C. Otherwise, both ortho and para-substituted products are formed instead of
the exclusive formation of the para-substituted product.
In addition, phenolic compounds can be sulfonomethylated. In general, any
position ortho or para to a phenolic hydroxy group can be converted to an ionic group,
e.g. a sulfonomethylated group as illustrated in Figure 6 where L = -SO3). The wave lines
represent remainder oligomer segments not shown.
Multi-hydroxy phenols as depicted in Fig. 3 and in some cases hydroxymethyl-substituted
phenols can be used. At least one reactive site, however, should be available to enable
reaction of the modifying agent with the phenolic resin precursor to form the dispersion.
The reactive site can be, for example, an active hydrogen ortho or para to a phenolic
hydroxy group. In Figure 6, the Ri and R2 groups are, independently, hydrogen or
organic radicals such as alkyl, aryl, arylalkyl, or a phenolic novolak. Preferred examples
include hydrogen, methyl, ethyl, and phenolic novolaks. Reagents for converting a
novolak to the sulfonomethyl substituted product include 1) reaction with a formaldehyde
source and either sodium bisulite, and sodium hydrosulfite, or (2) reaction with a
sulfonomethylated resole.
Alternatively a novolak can be reacted with a formaldehyde source to make a
conventional resole. Any resole can be reacted with an alkyl phosphite, preferably a
trialkylphosphite, e.g., trimethyl phosphite, to give a phosphonate ester group which when
followed by hydrolysis gives the desired novolak with phosphonic acid or
monoesterphosphonic acid groups.
Representative aliphatic structures include sulfonate-aldehyde structures as illustrated in
Figure 8 (1-5).
The following references describe synthetic routes corresponding with the numbers in
series figure 8:
1) Willems, Bull. Soc. Chim Belg., 64, 409, 425 (1955).
Finch, H.D., J.Org. Chem., 27, 649-651 (1962).
2) Johnson, T.J., Jones, R.A., Tetrahedron, 34, 547-551 (1978).
3) Vareri, F.S. et al., Monatsh. Chem., 120, 967-972 (1989).
4) Brock, N. et al, Arzneim. Forsch, 29, 659-661 (1979).
5) Backer; van der Veen, Reel. Trav. Chim. Pays-Bos, 55, 897 (1936).
As mentioned, the modifying agent can contain other functional groups, e.g.,
oxygen, nitrogen, non-ionizable sulfur groups, and the like, for example, a nitrogen-
containing sulfonate compound such as a sulfonate-amide, -amine, -imine, or-urea
compound as illustrated in series figures 9. The modifying agents include aliphatic or
aromatic nitrogen-containing compounds which contain an ionic group, wherein nitrogen-
containing functional groups provide reactive hydrogen as the reaction enabling moiety.
In series figures 9, various sultones are shown in reaction with an aliphatic amide (9-1)
with base, and a urea with base (9-5). Guanidine (9-2), thiourea (9-3), or
thiosemicarbazide (9-4) react spontaneously with sultones to make sulfonated derivatives.
Sultones having 4, 5, 6, 7 or 8 membered rings react analogously to couple with such
nitrogen compounds, leaving a remaining phenolic-reactive hydrogen on the nitrogen
group. Exemplary known reagents containing amide-, imine-, amine-, urea-, amidine-,
guanidine-, semicarbazide-, hydrazide-, thiohydrazide-, thioamide-, thiourea-,
thiosemicarbazide-, carbamate-, thiocarbamatc-, dithiocarbamate-, and isothiourea groups
are useful in ring-opening coupling with a sultone to make sulfonated amides, sulfonated
imines, sulfonated amines, sulfonated ureas, sulfonated amidines, sulfonated guanidine,
sulfonated semicarbazides, sulfonated hydrazides, sulfonated thiohydrazides, sulfonated
thioamides, sulfonated thioureas, sulfonated thiosemicarbazides, sulfonated carbamates,
sulfonated thiocarbamates, sulfonated dithiocarbamates, and sulfonated isothioureas.
Reactions in series 9-3 to 9-5 are made by methods analogous to those in 9-1 and 9-2.
The following references describe synthetic routes corresponding with the numbers in
series figure 8:
1) Willems, Bull, Soc. Chim Belg., 64, 409, 425 (1955).
Finch, H.D., J.Org. Chem., 27, 649-651 (1962).
2) Johnson, T.J., Jones, R.A., Tetrahedron, 34, 547-551 (1978).
3) Vareri, F.S. et al., Monatsh. Chem., 120, 967-972 (1989).
4) Brock, N. et al., Arzneim. Forsch, 29, 659-661 (1979).
5) Backer; van der Veen, Reel. Trav. Chim. Pays-Bas, 55, 897 (1936).
As mentioned, the modifying agent can contain other functional groups, e.g.,
oxygen, nitrogen, non-ionizable sulfur groups, and the like, for example, a nitrogen-
containing sulfonate compound such as a sulfonate-amide, -amine, -imine, or-urea
compound as illustrated in series figures 9. The modifying agents include aliphatic or
aromatic nitrogen-containing compounds which contain an ionic group, wherein nitrogen-
containing functional groups provide reactive hydrogen as the reaction enabling moiety.
In series figures 9, various sultones are shown in reaction with an aliphatic amide (9-1)
with base, and a urea with base (9-5). Guanidine (9-2), thiourea (9-3), or
thiosemicarbazide (9-4) react spontaneously with sultones to make sulfonated derivatives.
Sultones having 4, 5, 6, 7 or 8 membered rings react analogously to couple with such
nitrogen compounds, leaving a remaining phenolic-reactive hydrogen on the nitrogen
group. Exemplary known reagents containing amide-, imine-, amine-, urea-, amidine-,
guanidine-, semicarbazide-, hydrazide-, thiohydrazide-, thioamide-, thiourea-,
thiosemicarbazide-, carbamate-, thiocarbamate-, dithiocarbamate-, and isothiourea groups
are useful in ring-opening coupling with a sultone to make sulfonated amides, sulfonated
imines, sulfonated amines, sulfonated ureas, sulfonated amidines, sulfonated guanidine,
sulfonated semicarbazides, sulfonated hydrazides, sulfonated thiohydrazides, sulfonated
thioamides, sulfonated thioureas, sulfonated thiosemicarbazides, sulfonated carbamates,
sulfonated thiocarbamates, sulfonated dithiocarbamates, and sulfonated isothioureas.
Reactions in series 9-3 to 9-5 are made by methods analogous to those in 9-1 and 9-2.
Reactions 9-6 utilizes 2-aminoethyl sulfonic acid. Correspondingly an 3-aminopropyl
sulfonic acid could be used . Sulfonic acid structures as shown, are understood to be
readily converted to corresponding sulfonate structures.
In the above FIGS. 9-6 and 9-7, R is H or C,-C10 substituted or unsubstituted, linear or
branch alkyl groups, C^-C^ ary], and Q-C30 aryl substituted Cj-Cjo alkyl groups.
Another route starts with an amine which is reacted with carbon disulfide, followed by
addition of a sultone to make a sulfonated dilhiocarbamate.
The following references describe synthetic routes to these structures and correspond to
the reference numbers in series figures 9:
1) Suga, K. et al., Aust. J. Chem., 21, 2333-2339 (196S).
2) Fujii, A.; Cook, E.S., J. Med. Chem., 18, 502-505 (1975).
Mozolis et al., MoksluAdad. Darb. Ser. B., 4, 77, 80 (1976)
3) U.S. Patent No. 2,833,781 (1954).
Schramm, et al., J. Am. Chem. Soc, 11, 6231 (1955).
4) Johnston, T.P.; Stnngfellow, C.R., J. Med. Chem., 9, 921-924 (1966).
5) Zeid, I. et al., Justus Liebigs Ann. Chem., 761, 118-120 (1972).
Zeid, I, Chem. hid. (London), 380 (1973).
Schoeberl et al. Justus Liebigs Ann. Chem., 614, 83, 94 (1958).
If sulfonic acid structures are shown, it is understood that they can be converted to
corresponding sulfonate structures.
Phosphorous-containing ionic moieties include, for example, salts of phosphono
(-P(0)(0)22-M,+M2+), phosphonocster (-P(0)(OR)0'M,+), and phosphino (-P(O)O'M,)
groups, wherein Mj and M2 each and independently represent monovalent ions, and R
represents an organic radical. Modifying agents comprising these phosphorous-
containing moieties can be alkyl or aryl.
Examples of phosphono and phosphino compounds are illustrated in Figure 6,
wherein it is understood by one skilled in the art that the acid form can be readily
converted to a corresponding salt form.
An exemplary synthesis of a phosphonomethylatcd phenol is:
where Z is Oil, H, phenolic, carboxylic acid, carboxylic ester or carboxylic amide
with the proviso that there must be a least one active hydrogen on either the aromatic
ring and/or Z must be phenolic reactive in a condensation reaction. If 3
phosphonomethyl (CH2P03-Na+) groups are present, then Z must be phenolic.
In this method, a ortho, ortho' or para mcthylolated phenol (i.e. any resole) can react with
P(OR)3 to form the phosphonoester and hydrolyzed to the phosphonic acid or the
monophosphonic ester.
In addition, the modifying agent can contain a mono- or disubstituted
phosphonomethyl amino group as illustrated in Figure 10. In this embodiment, a
phenolic amine compound can be phosphonomethylated using formaldehyde in
conjunction with H3PO3 (or formaldehyde with H2P02 to carry out
phosphinomethylation) to make the dispersing, ionic functionality.
rhosphonomethylatcdamlno-phenols
FIG. 10
Tt is understood by one skilled in the art that the illustrated acid forms in FIG. 10 can be
converted to salt forms.
In addition, the modifying agent can be, for example, a derivative of
vinylphosphonic acid or vinylidenediphosphonic acid. These are prepared by Michael
Addition as illustrated in Figure 11. Again, it is understood by those skilled in the art that
illustrated acidic forms can be converted to corresponding salt structures having
monovalent ions.
Still further, the modifying agent can be, for example, a phosphonic aldehyde
compound, including an aliphatic phosphonic aldehyde compound, as illustrated in Figure
12. Illustrated acid forms are understood by one skilled in the art to be convertible to
corresponding salt forms having monovalent ions.
References which discuss these compounds include (numbers by the reference correlate
with numbers in Figure 12):
l)Natchev. LA., Tetrahedron, 44(5), 1511-1522 (1988).
2) Rudinskas, A.J.; Hullar, T.L., J. Med. Chem., 19, 1367-1371 (1976).
3) Page, P.; Blonski, C; Perie, J., Tetrahedron Lett., 36(44), 8027-8030 (1995).
4) Page, P.; Blonski, C; Perie, J., Bioorgan. Med. Chem., 7(7), 1403-1412 (1999).
In Figure 13, embodiments based on modifying agents comprising nitrogen and
phosphorous are illustrated, including phosphonic amides.
Reaction (13-1) is further described in Stutz, H., Henning, H.-G., ZChern., 15, 52-54
(1975). Illustrated acid forms are understood by one skilled in the art to be convertible to
corresponding salt forms having monovalent ions. The R and R' groups of FIG. 13-2,
independently, are hydrogen, aliphatic groups such as, for example, methyl, ethyl, propyl,
or phenyl.
In addition, the modifying agent can contain a formy] group as the phenolic-
reactive group, an activated carboxylic acid moiety (carboxylate) as the ionic group.
Examples include a,a-difluorocarboxylic modifying agents are illustrated in Figure 14-1.
Step 4
FIG.14-2
Steps 1 and 3 are disclosed in DE 2,234,802. Steps 2 and 4 are proposed. The hydrolysis
step 4 is adaptable from the work of J. Chaussard et ai, Synthesis (5), 369-381 (1990).
The reaction-enabling functional moiety of the modifying agent can be any
functional group that provides a site on the modifying agent for undergoing condensation
with a phenolic resin. If the phenolic resin precursor is a resole, the modifying agent
reacts with an alkylol or benzyl ether group of the resole. If the modifying agent is
aromatic, the reaction-enabling functional moiety is a substituent on the aromatic ring that
causes a site on the ring to be reactive to the alkylol or benzyl ether of the resole
WOrt3/0W37'6 PCT/US03/1J617
28
precursor. An example of such a substituent is a hydroxy or hydroxyalkyl, with hydroxy
being preferred. The hydroxy- or hydroxyalkyl-substituted aromatic modifying agent is
reactive at a site ortho and/or para to the hydroxy substituent. In other words, the
aromatic modifying agent is bonded to, or incorporated into the phenolic resin precursor
at the active hydrogen sites on the aromatic ring of the modifying agent that are ortho
and/or para to a phenolic hydroxy. At least two reaction-enabling functional moieties are
preferred to enhance the reactivity of the aromatic modifying agent with the phenolic
resin precursor.
Alternatively, the reaction-enabling functional moiety of the modifying agent
can be a formyl group (-CHO), preferably attached to a carbon atom of an aromatic ring.
In this instance, the phenolic resin precursor is a novolak rather than a resole. The
novolak precursor is reacted via an acid catalyzed aldehyde condensation reaction with
the formyl group-containing modifying agent so that the formyl group forms a divalent
methylene linkage to an active site on an aromatic ring of the backbone structure of the
novolak precursor. Consequently, the modifying agent structure (including the ionic
moiety) is incorporated into the phenolic structure through the generated methylene
linkage. Examples of such formyl group-containing modifying agents include 2-
formylbenzene sulfonate, 5-formyIfuran sulfonate and (R)(S03)CH-CH2-C(0)(H)
compounds wherein R is C,-C4 alkyl groups.
Another alternative reaction-enabling functional moiety could be a diazo group
(-N,+), preferably attached to a carbon atom of an aromatic ring. In this instance, the
phenolic resin precursor is a novolak rather than a resole. The novolak precursor is
reacted via a diazo coupling reaction with the diazo group-containing modifying agent so
that the diazo group forms a divalent diazo linkage (-N=) to an active site on an aromatic
ring of the backbone structure of the novolak precursor. Consequently, the modifying
agent structure (including the ionic moiety) is incorporated into the phenolic structure
through the diazo linkage. An example of such diazo modifying agents is l-diazo-2-
naphthol-4-suIfonic acid.
The modifying agent also can optionally include a functional moiety that is
capable of chelating with a metal ion that is present on a substrate surface on which the
phenolic resin dispersion is applied. The chelating group remains as a residual group
after the condensation of the phenolic resin precursor and the aromatic modifying agent.
Typically, the chelating group is a substituent on the aromatic ring that is capable of
forming a 5- or 6-membered chelation structure with a metal ion. Examples of such
substituents include hydroxy and hydroxyalkyl, with hydroxy being preferred. At least
two such functional groups must be present on the modifying agent molecule to provide
the chelating. In the case of an aromatic modifying agent, the chelating groups should be
located in an ortho position relative to each other. A significant advantage of the
invention is that hydroxy or hydroxyalkyl substituents on the aromatic modifying agent
can serve two roles - condensation enablement and subsequent metal chelating.
An aromatic modifying agent is particularly advantageous. Preferably, the ionic
group and the reaction-enabling moiety are attached to different aromatic rings in the case
of multi-aromatic ring modifying agents. The ionic group, particularly sulfonate, appears
to have a strong deactivating effect on condensation reactions of the ring to which it is
attached. However, it should be recognized that this consideration for the location of the
ionic and reaction-enabling moieties is not applicable to the formyl group-containing
modifying agent and diazo modifying agent.
A preferred structure for the aromatic modifying agent is represented by
formulae la or lb below:
Formula la
WO 03/093376. PCT/US03/13617
30
wherein X is the ionic group; Y is the reaction-enabling substituent; Z is the chelating
substituent; L1 is a divalent linking group such as an alkylene radical (for example,
methylene) or a diazo (-N=N-); a is 1; b is 1 to 4; m is 0 or 1; and c and d are each
independently 0 to 3, provided there are not more than 4 substituents on each aromatic
ring. If a chelating group Z is present it is positioned ortho to another chelating group Z
or to Y. It should be recognized that the reaction-enabling substituent Y may also act as a
chelating substituent. In this instance, the aromatic modifying agent may not include an
independent chelating substituent Z. An aromatic modifying agent according to formulae
la or lb could also include other substituents provided they do not adversely interfere with
the ionic group or the condensation reaction.
Illustrative aromatic modifying agents include salts of 6,7-dihydroxy-2-
napthalenesulfonate; 6,7-dihydroxy-l-naphthalenesuIfonate; 6,7-dihydroxy-4-
naphthalenesulfonate; Acid Red 88; Acid Alizarin Violet N; Erichrome Black T;
Erichrome Blue Black B; Brilliant Yellow; Crocein Orange G; Biebrich Yellow; and
Palatine Chrome Black 6BN. 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt is the
preferred aromatic modifying agent.
It should be recognized that the preferred sulfonate modification contemplated
herein involves an indirect sulfonation mechanism. In other words, the aromatic
modifying agent includes a sulfonate group and is reacted with another aromatic
compound (the phenolic resin precursor) to obtain the chain extended, sulfonate-modified
phenolic resin product. This indirect sulfonation is distinctly different than direct
sulfonation of the phenolic resin precursor.
Any phenolic resin could be employed as the phenolic resin precursor, but it has
been found that resoles are especially suitable. The resole precursor should have a
sufficient amount of active alkylol or benzyl ether groups that can initially condense with
the modifying agent and then undergo further subsequent condensation. Of course, the
phenolic resin precursor has a lower molecular weight than the final dispersed resin since
the precursor undergoes condensation to make the final dispersed resin. Resoles are
prepared by reacting a phenolic compound with an excess of an aldehyde in the presence
of a base catalyst. Resole resins are usually supplied and used as reaction product
mixtures of monomeric phenolic compounds and higher molecular weight condensation
into a translucent dispersion), the acid catalyst and a greater amount of multi-hydroxy
phenolic compound(s) is added to the reaction mixture. Pyrocatechol (also simply known
as catechol) is a preferred multi-hydroxy phenolic compound for reacting in the first stage
and resorcinol is a preferred multi-hydroxy phenolic compound for reacting in the second
stage.
Hydrophilic novolaks typically have a hydroxy equivalents of between 1 and 3
per aromatic ring. Preferably, dispersed hydrophilic novolaks according to the invention
have a hydroxy equivalents of 1.1 to 2.5, more preferably 1.1 to 2.0. The hydroxy
equivalents is calculated based on the amount of multi-hydroxy phenolic compounds used
to make the novolak.
According to a preferred embodiment, the dispersed phenolic resin reaction
product contains a mixture of oligomers having structures believed to be represented by
the following formulae Ha or lib:
wherein X, Y, Z and L1 and subscripts a, b, c, d and m are the same as in formulae la and
lb, e is 1 to 6, V is a divalent linking group and Ph is the phenolic resin backbone
structure, provided the -(L2 -Ph) group(s) is(are) ortho or para to a Y group. V depends
upon the particular phenolic resin, but typically is a divalent alkylene radical such as
methylene (-CH,-) or oxydimethylene (-CH2-0-CH,-). Preferably, e is 2 and the -(L2-Ph)
groups are in para position to each other.
products having alkylol (-ArCHj-OH) or benzyl ether termination (-ArCHj-O-CILAr),
wherein Ar is an aryl group. These resole mixtures or prepolymers (also known as stage
A resin) can be transformed into three-dimensional, crosslinked, insoluble and infusible
polymers by the application of heat.
The reactants, conditions and catalysts for preparing resoles suitable for the resole
precursor of the present invention are well-known. The phenolic compound can be any of
those previously listed or other similar compounds, although multi-hydroxy phenolic
compounds are undesirable. Particularly preferred phenolic compounds for making the
resole precursor include phenol per se and alkylated phenol. The aldehyde also can be
any of those previously listed or other similar compounds, with formaldehyde being
preferred. Low molecular weight, water soluble or partially water soluble resoles are
preferred as the precursor because such resoles maximize the ability to condense with the
modifying agent. The F/P ratio of the resole precursor should be at least 0.90. Illustrative
commercially available resoles that are suitable for use as a precursor include a partially
water soluble resole available from Georgia Pacific under the trade designation BRL 2741
and a partially water soluble resoles available from Schenectady International under the
trade designations HRJ11722 and SG3100.
Preferably, the dispersed novolak is produced by reacting or mixing 1 mol of
modifying agent(s) with 2-20 mol of phenolic resin (preferably resole) precursor(s) and,
preferably, 2-20 mol of multi-hydroxy phenolic compound(s). An aldehyde compound,
preferably formaldehyde, is also required to make the novolak. The aldehyde compound
can optionally be added as a separate ingredient in the initial reaction mixture or the
aldehyde compound can be generated in situ from the resole precursor. The resole
precursor(s), multi-hydroxy phenolic compound(s) and modifying agcnt(s) co-condcnsc
to form the dispersed novolak. The reaction typically is acid catalyzed with an acid such
as phosphoric acid. The F/P ratio of aldehyde compound(s) to combined amount of
resole precursor(s) and multi-hydroxy phenolic compound(s) in the initial reaction
mixture preferably is less than 0.9. Preferably, synthesis of the dispersed novolak is a two
stage reaction. In the first stage, the resole precursors) is reacted with the modifying
agent(s) and, optionally, a small amount of multi-hydroxy phenolic compound(s). Once
this first stage reaction has reached the desired point (i.e. the resin can be readily formed
According to a preferred embodiment wherein the phenolic resin is a novolak and
the modifying agent is a naphthalene having a ionic pendant group X and two reaction-
enabling substituents Y, the dispersed phenolic resin reaction product contains a mixture
of oligomers having structures believed to be represented by the following formula IV:
wherein X and Y are the same as in formulae la and lb, a is 0 or 1, n is 0 to 5 and R4 is
independently hydroxyl, alley!, aryl, alkylaryl or aryl ether. Preferably, R4 is tcrt-butyl. If
6,7-dihydroxy-2-naphthalenesulfonate, sodium salt is the modifying agent, X will be S03"
Na+ and each Y will be OH. In this case the hydroxy groups for Y will also act as
chelating groups with a metal ion.
It should be recognized that the dispersed phenolic resin reaction product may also
contain oligomers or compounds having structures that vary from the idealized structures
shown in formula IV.
If the modifying agent is a sulfur-containing ionic group, the resulting modified
phenolic resin preferably has a carbon/sulfur atom ratio of 20:1 to 200:1, preferably 20:1
to 100:1. If the sulfur content is greater than the 20:1 carbon/sulfur atom ratio, the
modified phenolic resin begins to become water soluble, is more stable with respect to
multivalent ions and is difficult to thermoset. These characteristics are adverse to the
preferred use of the phenolic resin dispersion of the invention. If the sulfur content is
below the 200:1 carbon/sulfur atom ratio, then the resin dispersion cannot maintain its
stability. Viewed another way, the dispersed phenolic resins have 0.01 to 0.10, preferably
0.03 to 0.06, equivalents of sulfonate functionality/100 g resin. The aqueous dispersion
of the phenolic resin preferably has a solids content of 1 to 50, preferably 15 to 30 U)t. */>.
The modifying agent and the phenolic resin precursor can be reacted under
conditions effective to promote condensation of the modifying agent with the phenolic
resin precursor. The reaction is carried out in water under standard phenolic resin
condensation techniques and conditions. The reactant mixture (including water)
generally is heated from 50 to 100 °C under ambient pressure, although the specific
temperature may differ considerably depending upon the specific reactants and the
desired reaction product. The resulting product is a concentrate that is self-dispersible
upon the addition of water and agitation to reach a desired solids content. The final
dispersion can be filtered to remove any gelled agglomerations.
The intermediate modified resoles or novolaks that are initially produced in the
synthesis are not necessarily water dispersible, but as the chain extension is advanced the
resulting chain extended modified resoles or novolaks become progressively more water
dispersible by simple mechanical agitation. The chain extension for the dispersed resole
is determined by measuring the viscosity of the reaction mixture. Once the resole
reaction mixture has a reached the desired viscosity, which varies depending upon the
reactant composition, the reaction is stopped by removing the heat. The chain extension
for the dispersed novolak is determined by pre-selecting the F/P ratio of the total reaction
mixture (in other words, the amount of aldehyde compound(s) relative to the amount of
phenolic(s) in both the first and second stages). The reaction for the novolak is allowed
to proceed until substantially all the total amount of the reactants have reacted. In other
words, there is essentially no unreacted reactant remaining. Preferably, the molecular
weight (i.e., chain extension) of the novolak should be advanced to just below the gel
point.
The novolak dispersion can be present in the metal treatment composition in any
amount. Preferably, it is present in an amount of 1 to 20/ more preferably, 2 to 6/ based
on the total weight of the non-volatile components of the composition.
The phenolic resin dispersion forms environmentally (especially corrosion)
resistant, non-resolvatable films when applied to a metal surface and cured. As used
herein, "non-resolvatable" means that the film does not resolvate when an aqueous
covercoat is applied to the film before it is thermoset. If the film resolvated, the
components of the film would dissolve or disperse into the aqueous covercoat thus
destroying any advantage intended from the formation of the film on a surface. The low
ionic content of the modified phenolic resin dispersion (relative to water soluble phenolic
resins) allows them to behave similarly to non-ionically modified resins and form very
water resistant films on curing.
The acid can be any acid that is capable of reacting with a metal to generate
multivalent ions. Illustrative acids include hydrofluoric acid, phosphoric acid, sulfuric
acid, hydrochloric acid and nitric acid. In the case of steel the multivalent ions will be
ferric and/or ferrous ions. Aqueous solutions of phosphoric acid are preferred. When the
acid is mixed into the composition presumably the respective ions are formed and exist as
independent species in addition to the presence of the free acid. In other words, in the
case of phosphoric acid, phosphate ions and free phosphoric acid co-exist in the
formulated final multi-component composition. The acid preferably is present in an
amount of 5 to 300 parts by weight, more preferably 10 to 160 parts by weight, based on
100 parts by weight of the phenolic novolak resin dispersion (A).
Water, preferably deionized water, is utilized in the metal treatment composition
of the invention in order to vary the solids content. Although the solids content may be
varied as desired, the solids content of the metal treatment composition typically is 1 to
10, preferably 3 to 6%. Since the metal treatment composition is waterborne it is
substantially free of volatile organic compounds.
The resulting coating from application of the metal treatment composition is a
thin, tightly bound interpenetrating organic/inorganic matrix of phenolic/metal
phosphates at the metal substrate interface. This matrix can be further flexibilized witli
polymers. The flexibilizer (C) is any material that contributes flexibility and/or toughness
to the film formed from the composition. The toughness provided by the flexibilizer
provides fracture resistance to the film. The flexibilizer should be non-glassy at ambient
temperature and be an aqueous emulsion latex or aqueous dispersion that is compatible
with the phenolic novolak resin dispersion (A). The flexibilizer preferably is formulated
into the composition in the form of an aqueous emulsion latex or aqueous dispersion
Suitable flexibilizers include aqueous Iatices, emulsions or dispersions of
(poly)butadiene, neoprene, styrene-butadiene rubber, acrylonitrile-butadiene rubber (also
known as nitrile rubber), halogenated polyolefin, acrylic polymer, urethane polymer,
ethylene-propylene copolymer rubber, ethylene-propylene-diene terpolymer rubber,
styrene-acrylic copolymer, polyamide, po]y(vinyl acetate) and the like. Halogenated
polyolefins, nitrile rubbers and styrene-acrylic copolymers are preferred.
A suitable styrene-acrylic polymer latex is commercially available from
Goodyear Tire & Rubber under the trade designation PLIOTEC and described, for
example, in U.S. Patents No. 4,968,741; 5,122,566 and 5,616,635. According to U.S.
Patent No. 5,616,635, such a copolymer latex is made from 45-85 weight percent vinyl
aromatic monomers, 15-50 weight percent of at least one alkyl acrylate monomer and 1-6
weight percent unsaturated carbonyl compound. Styrene is the preferred vinyl aromatic
monomer, butyl acrylate is the preferred acrylate monomer and acrylic acid and
methacrylic acid are the preferred unsaturated carbonyl compound. The mixture for
making the latex also includes at least one phosphate ester surfactant, at least one water-
insoluble nonionic surface active agent and at least one free radical initiator.
If nitrile rubber is the flexibilizer, it is preferably mixed into the composition as
an emulsion latex. It is known in the art that nitrile rubber emulsion latices are generally
made from at least one monomer of acrylonitrile or an alkyl derivative thereof and at least
one monomer of a conjugated diene, preferably butadiene. According to U.S. Patent No.
4,920,176 the acrylonitrile or alkyl derivative monomer should be present in an amount of
0 to 50 percent by weight based on the total weight of the monomers. The conjugated
diene monomer should be present in an amount of 50 percent to 100 percent by weight
based on the total weight of the monomers. The nitrile rubbers can also optionally
include various co-monomers such as acrylic acid or various esters thereof, dicarboxylic
acids or combinations thereof. The polymerization of the monomers typically is initiated
via free radical catalysts. Anionic surfactants typically are also added. A suitable nitrile
rubber latex is available from B.F. Goodrich under the trade designation HYCAR.
Representative halogenated polyolefins include chlorinated natural rubber,
chlorine- and bromine-containing synthetic rubbers including polychloroprene,
chlorinated polychloroprene, chlorinated polybutadiene, hexachloropentadiene,
butadiene/halogenated cyclic conjugated diene adducts, chlorinated butadiene styrene
copolymers, chlorinated ethylene propylene copolymers and ethylene/propylene/non-
conjugated diene terpolymers, chlorinated polyethylene, chlorosulfonated polyethylene,
po!y(2,3-dichIoro-l,3-butadiene), brominatedpoly(2,3-dichloro-l,3-butadiene),
copolymers of a-haloacrylonitriles and 2,3-dichloro-l,3-butadiene, chlorinated poly(vinyJ
chloride) and the like including mixtures of such halogen-containing elastomers.
Latices of the halogenated polyolefin can be prepared according to methods
known in the ait such as by dissolving the halogenated polyolefin in a solvent and adding
a surfactant to the resulting solution. Water can then be added to the solution under high
shear to emulsify the polymer. The solvent is then stripped to obtain a latex. The latex
can also be prepared by emulsion polymerization of the halogenated ethylenically
unsaturated monomers.
Butadiene latices are particularly preferred as the flexibilizer (C). Methods for
making butadiene latices are well-known and are described, for example, in U.S. Patents
No. 4,054,547 and 3,920,600, both incorporated herein by reference. In addition, U.S.
Patents No. 5,200,459; 5,300,555; and 5,496,S84 disclose emulsion polymerization of
butadiene monomers in the presence of polyvinyl alcohol and a co-solvent such as an
organic alcohol or a glycol.
The butadiene monomers useful for preparing the butadiene polymer latex can
essentially be any monomer containing conjugated unsaturation. Typical monomers
include 2,3-dichloro-l,3-butadiene; 1,3-butadienc; 2,3-dibromo-l,3-butadieneisoprene;
isoprene; 2,3-dimethylbutadiene; chloroprene; bromoprene; 2,3-dibromo-l,3-butadiene;
1,1,2-lrichlorobutadienc; cyanoprene; hexachlorobutadiene; and combinations thereof. It
is particularly preferred to use 2,3-dichloro-l,3-butadiene since a polymer that contains as
its major portion 2,3-dichloro-l,3-butadiene monomer units has been found to be
particularly useful in adhesive applications due to the excellent bonding ability and
barrier properties of the 2,3-dichloro-l,3-butadiene-based polymers. As described above,
an especially preferred embodiment of the present invention is one wherein the butadiene
polymer includes at least 60 weight percent, preferably at least 70 weight percent, 2,3-
dichloro-l,3-butadiene monomer units.
The butadiene monomer can be copolymerized with other monomers. Such
copolymerizable monomers include a-haloacrylonitriles such as a-bromoacrylonitrile and
a-chloroacrylonitrile; cc,p-unsaturated carboxylic acids such as acrylic, methacrylic, 2-
cthylacrylic, 2-propylacrylic, 2-butylacrylic and itaconic acids; alkyl-2-haloacrylates such
as ethyl-2-chloroacrylate and ethyl-2-bromoacrylate; oc-bromovinylketone; vinylidene
chloride; vinyl toluenes; vinylnaphthalenes; vinyl ethers, esters and ketones such as
methyl vinyl ether, vinyl acetate and methyl vinyl ketone; esters amides, and nitriles of
acrylic and methacrylic acids such as ethyl acrylate, methyl methacrylate, glycidyl
acrylate, methacrylamide and acrylonitrile; and combinations of such monomers.
The copolymerizable monomers, if utilized, are preferably oc-haloacrylonitrile and/or a,p-
unsaturated carboxylic acids. The copolymerizable monomers may be utilized in an
amount of 0.1 to 30 weight percent, based on the weight of the total monomers utilized to
form the butadiene polymer.
In carrying out the emulsion polymerization to produce the latex other optional
ingredients may be employed during the polymerization process. For example,
conventional anionic and/or nonionic surfactants may be utilized in order to aid in the
formation of the latex. Typical anionic surfactants include carboxylates such as fatty acid
soaps from lauric, stearic, and oleic acid; acyl derivatives of sarcosine such as methyl
glycine; sulfates such as sodium lauryl sulfate; sulfated natural oils and esters such as
Turkey Red Oil; alkyl aryl polyether sulfates; alkali alkyl sulfates; ethoxylated aryl
sulfonic acid salts; alkyl aryl polyether sulfonates; isopropyl naphthalene sulfonates;
sulfosuccinates; phosphate esters such as short chain fatty alcohol partial esters of
complex phosphates; and orthophosphate esters of polyethoxylated fatty alcohols.
Typical nonionic surfactants include ethoxylated (ethylene oxide) derivatives such as
ethoxylated alkyl aryl derivatives; mono- and polyhydric alcohols; ethylene
oxide/propylene oxide block copolymers; esters such as glyceryl monostearate; products
of the dehydration of sorbitol such as sorbitan monostearate and polyethylene oxide
sorbitan monolaurate; amines; lauric acid; and isopropenyl halide. A conventional
surfactant, if utilized, is employed in an amount of 0.01 to 5 parts, preferably 0.1 to 2
parts, per 100 parts by weight of total monomers utilized to form the butadiene polymer.
In the case of dichlorobutadicne homopolymers, anionic surfactants are
particularly useful. Such anionic surfactants include alkyl sulfonates and alkyl aryl
sulfonates (commercially available from Stepan under the trade designation POLYSTEP)
and sulfonic acids or salts of alkylated diphenyl oxide (for example, didodecyl
diphenyleneoxide disulfonate or dihexyl diphenyloxide disulfonate commercially
available from Dow Chemical Co. under the trade designation DOWFAX).
Chain transfer agents may also be employed during emulsion polymerization in
order to control the molecular weight of the butadiene polymer and to modify the physical
properties of the resultant polymer as is known in the art. Any of the conventional
organic sulfur-containing chain transfer agents may be utilized such as alkyl mercaptans
and dialkyl xanthogcn disulfides.
The emulsion polymerization is typically triggered by a free radical initiator.
Illustrative free radical initiators include conventional redox systems, peroxide systems,
azo derivatives and hydroperoxide systems. The use of a redox system is preferred and
examples of such systems include ammonium persulfate/sodium metabisulfite, ferric
sulfate/ascorbic acid/hydroperoxide and tributylborane/hydroperoxide, with ammonium
persulfate/sodium metabisulfite being most preferred.
The emulsion polymerization is typically carried out at a temperature of 10°-
90°C, preferably 40°- 60°C. Monomer conversion usually ranges from 70-100,
preferably 80-100, percent. The latices preferably have a solids content of 10 to 70, more
preferably 30 to 60, percent; a viscosity between 50 and 10,000 centipoise at 25°C; and a
particle size between 60 and 300 nanometers.
Especially preferred as the butadiene latex is a butadiene polymer that has been
emulsion polymerized in the presence of a styrene sulfonic acid, styrene sulfonate,
poly(styrene sulfonic acid), or poly(styrene sulfonate) stabilizer to form the latex.
Poly(styrene sulfonate) is the preferred stabilizer. This stabilization system is particularly
effective for a butadiene polymer that is derived from at least 60 weight percent
dichlorobutadiene monomer, based on the amount of total monomers used to form the
butadiene polymer. The butadiene polymer latex can be made by known emulsion
polymerization techniques that involve polymerizing the butadiene monomer (and
copolymerizable monomer, if present) in the presence of water and the styrene sulfonic
acid, styrene sulfonate, poly(styrene sulfonic acid), or poly(styrene sulfonate) stabilizer.
The sulfonates can be salts of any cationic groups such as sodium, potassium or
quaternary ammonium. Sodium styrene sulfonate is a preferred styrene sulfonate
compound. Poly(styrene sulfonate) polymers include poly(styrene sulfonate)
homopolymer and polystyrene sulfonate) copolymers such as those with maleic
anhydride. Sodium salts of poly(styrene sulfonate) are particularly preferred and are
commercially available from National Starch under the trade designation VERSA TL.
The poly(styrene sulfonate) can have a weight average molecular weight from 5 x 104 to
1.5 x 106, with 1.5 x 105 to 2.5 x 105 being preferred. In the case of a polystyrene
sulfonate) or poly(styrene sulfonic acid) it is important to recognize that the emulsion
polymerization takes place in the presence of the pre-formed polymer. In other words,
the butadiene monomer is contacted with the pre-formed poly(styrene sulfonate) or
poly(styrene sulfonic acid). The stabilizer preferably is present in an amount of 0.1 to 10
parts, preferably 1 to 5 parts, per 100 parts by weight of total monomers utilized to form
the butadiene polymer.
The flexibilizer (C), if present, preferably is included in the composition in an
amount of 5 parts by weight to 300 parts by weight, based on 100 parts by weight
phenolic novolak resin dispersion (A). More preferably, the flexibilizer is present in an
amount of 25 parts by weight to 100 parts by weight, based on 100 parts by weight of the
phenolic novolak resin dispersion (A).
The modified phenolic resin dispersion can be cured to form a highly crosslinked
thermoset via known curing methods for phenolic resins. The curing mechanism can vary
depending upon the use and form of the phenolic resin dispersion. For example, curing
of the dispersed resole embodiment typically can be accomplished by subjecting the
phenolic resin dispersion to heat. Curing of the dispersed novolak embodiment typically
can be accomplished by addition of an aldehyde donor compound.
With a dispersed phenolic novolak embodiment, a curative should be introduced
in order to cure the film formed by the metal treatment composition. It should be noted
that the metal treatment composition cannot itself include a phenolic resin curative these
curatives are not storage stable under acidic conditions. Curing of novolak can also be
accomplished by the application of a curative-containing topcoat over the metal treatment
film. Typically, the metal treatment composition is applied to a metal surface (either
conventionally or via autodeposition) and then dried. The curative-containing topcoat
then is applied to the thus treated metal surface. The curative contained in the topcoat
can be an aldehyde donor compound or an aromatic nitroso compound. Topcoat
compositions that include either one or both of these curatives are well-known and
commercially available. If the metal treatment is a para-sulfonomethylated phenol, a
topcoat is not required.
The aldehyde donor can be essentially be any type of aldehyde known to react
with hydroxy aromatic compounds to form cured or crosslinked novolak phenolic resins.
Typical compounds useful as an aldehyde (e.g., formaldehyde) source in the present
invention include formaldehyde and aqueous solutions of formaldehyde, such as
formalin; acetaldehyde; propionaldehyde; isobutyraldehyde; 2-ethylhexaldehyde; 2-
methylpentaldehyde; 2-ethylhexaldchyde; benzaldehyde; as well as compounds which
decompose to formaldehyde, such as paraformaldehyde, trioxane, furfural, benzoxazines
and Mannich bases hexamethylenetetramine, anhydromaldehydeaniline, ethylene diamine
formaldehyde; acetals which liberate formaldehyde on heating; methylol derivatives of
urea and formaldehyde; methylol phenolic compounds; and the like.
It has been found that when the metal treatment composition is used in
combination with the primer described in U.S. Provisional Patent Application No.
60/072,779 (incorporated herein by reference), formaldehyde species generated from the
resole present in the primer appear- to co-cure the novolak in the metal treatment coating
via diffusion. In addition, curing or crosslinking of the novolak may occur through ionic
crosslinking and chelation with the metal ions generated by the acid-metal substrate
reaction.
Additionally, high molecular weight aldehyde homopolymers and copolymers can
be employed as a latent formaldehyde source in the practice of the present invention. A
latent formaldehyde source herein refers to a formaldehyde source which will release
formaldehyde only in the presence of heat such as the heat applied during the curing of an
adhesive system. Typical high molecular weight aldehyde homopolymers and
copolymers include (1) acetal homopolymers, (2) acetal copolymers, (3) gamma-polyoxy-
methylene ethers having the characteristic structure:
RI0O-(CH,p).-RM
and (4) polyoxymethylene glycols having the characteristic structure:
HO-(RI20)r(CH20)„-(R,30)rH
wherein Rl0 and Ru can be the same or different and each is an alkyl group having from
about 1 to 8, preferably 1 to 4, carbon atoms, R12 and R13 can be the same or different and
each is an alkylene group having from 2 to 12, preferably 2 to 8, carbon atoms; n is
greater than 100, and is preferably in the range from about 200 to about 2000; and x is in
the range from about 0 to 8, preferably 1 to 4, with at least one x being equal to at least 1.
The high molecular weight aldehyde homopolymers and copolymers are further
characterized by a melting point of at least 75° C, i.e. they are substantially inert with
respect to the phenolic system until heat activated; and by being substantially completely
insoluble in water at a temperature below the melting point. The acetal homopolymers
and acetal copolymers are well-known articles of commerce. The polyoxymethylene
materials are also well known and can be readily synthesized by the reaction of
monoalcohols having from 1 to 8 carbon atoms or dihydroxy glycols and ether glycols
with polyoxymethylene glycols in the presence of an acidic catalyst. A representative
method of preparing these crosslinking agents is described in U.S. Pat. No. 2,512,950,
which is incorporated herein by reference. Gamma-polyoxymethylene ethers are
generally preferred sources of latent formaldehyde and a particularly preferred latent
formaldehyde source for use in the practice of the invention is 2-polyoxymethylene
dimethyl ether.
The aromatic nitroso compound can be any aromatic hydrocarbon, such as
benzenes, naphthalenes, anthracenes, biphenyls, and the like, containing at least two
nitroso groups attached directly to non-adjacent ring carbon atoms. Such aromatic nitroso
compounds are described, for example, in U.S. Patent No. 3,258,38S; U.S. Patent No.
4,119,587 and U.S. Patent No. 5,496,884.
More particularly, such nitroso compounds are described as aromatic
compounds having from 1 to 3 aromatic nuclei, including fused aromatic nuclei, having
from 2 to 6 nitroso groups attached directly to non-adjacent nuclear carbon atoms. The
preferred nitroso compounds are the dinitroso aromatic compounds, especially the
dinitrosobenzenes and dinitrosonaphthalenes, such as the meta- or para-dinitrosobenzenes
and the meta- or para-dinitrosonaphthalenes. The nuclear hydrogen atoms of the aromatic
nucleus can be replaced by alky], alkoxy, cycloalkyl, aryl, aralkyl, alkaryl, arylamine,
arylnitroso, amino, halogen and similar groups. Thus, where reference is made herein to
"aromatic nitroso compound" it will be understood to include both substituted and
unsubstituted nitroso compounds.
Particularly preferred nitroso compounds are characterized by the formula:
(R)ra-Ar-(NOX
wherein Ar is selected from the group consisting of phcnylene and naphthalene; R is a
monovalent organic radical selected from the group consisting of alkyj, cycloalkyl, aryl,
aralkyl, alkaryl, arylamine and alkoxy radicals having from 1 to 20 carbon atoms, amino,
or halogen, and is preferably an alkyl group having from 1 to 8 carbon atoms; and m is 0,
1, 2, 3, or 4, and preferably is 0.
Exemplary suitable aromatic nitroso compounds include m-dinitrosobenzene, p-
dinitrosobenzene, m-dinitrosonaphthalene, p-dinitrosonaphthalcne, 2,5-dinitroso-p-
cymene, 2-methyl-l,4-dinitrosobenzcne, 2-methyl-5-chloro-l,4- dinitrosobenzene, 2-
fluoro 1,4- dinitrosobenzene, 2-mcthoxy- 1-3-dinitrosobenzene, 5-chloro-l,3-
dinitrosobenzenc, 2-benzyl-i,4-dinitrosobenzene, 2-cyclohexyl-l,4-dinitrosobenzenc and
combinations thereof. Particularly preferred are m-dinitrosobenzene and p-
ainilrosobenzene.
The aromatic nitroso compound precursor may be essentially any compound that
is capable of being converted, typically by oxidation, to a nitroso compound at elevated
temperatures, typically from about 140-200°C. The most common aromatic nitroso
compound precursors are derivatives of quinone compounds. Examples of such quinone
compound derivatives include quinone dioximc, dibenzoquinone dioxime, 1.2,4,5-
telrachlorobenzoquinone, 2-methyl-l,4-benzoquinone dioxime, 1,4-naphthoquinone
dioxime, 1,2-naphthoquinone dioxime and 2,6-naphthoquinone dioximc.
The control agent mentioned above is especially useful in the metal treatment
composition of the invention described above but it could also be useful in any multi-
component composition that includes an autodeposi tabic component. The autodepositable
component is any material that enables (either by itself or in combination with the other
components of the composition) the multi-component composition to autodeposit on a
metal surface. Preferably, the autodepositable component is any water-dispersible or
water soluble resin that is capable of providing autodeposition ability to the composition.
Such resins include those derived from ethylenically unsaturated monomers such as
polyvinylidene chloride, polyvinyl chloride, polyethylene, acrylic, acrylonitrile, polyvinyl
acetate and styrene-butadiene (see U.S. Patents No. 4,414,350; 4,994,521; and 5,427,863;
and PCT Published Patent Application No. WO 93/15154). Urethane and polyester resins
are also mentioned as being useful. Certain epoxy and epoxy-acrylate resins are also said
to be useful autodeposition resins (see U.S. Patent No. 5,500,460 and PCT Published
Patent Application No. WO 97/07163). Blends of these resins may also be used.
Especially suitable autodepositable resins are aqueous phenolic resin dispersions
described in co-pending, commonly assigned U.S. Patent No. 6,130,289, which is
incorporated herein by reference.
The novolak version of this dispersed resin is described above in connection with
the metal treatment composition. There is also a resole version with which the control
agent of the invention may be formulated into a multi-component composition.
The phenolic resin precursor and modifying agent used to make the dispersed
resole are the same as those described for the dispersed novolak. However, the dispersed
resole is produced by the reaction of 1 mol of modifying agent(s) with 1 to 20 mol of
phenolic resin precursor(s). A dispersed resole typically can be obtained by reacting a
resole precursor or a mixture of resole precursors with the modifying agent or a mixture
of agents without any other reactants, additives or catalysts. However, other reactants,
additives or catalysts can be used as desired. Multi-hydroxy phenolic compound(s) can
optionally be included in relatively small amounts in the reactant mixture for the resole.
Synthesis of the resole does not require an acid catalyst.
Hydrophilic resoles typically have a FTP ratio of at least 1.0. According to the
invention, hydrophilic resoles having a FTP ratio much greater than 1.0 can be
successfully dispersed. For example, it is possible to make an aqueous dispersion of
hydrophilic resoles having a F/P ratio of at least 2 and approaching 3, which is the
theoretical F/P ratio limit.
According to a particularly preferred embodiment wherein the dispersed
phenolic resin is a resole and the modifying agent is a naphthalene having a ionic pendant
group X and two reaction-enabling substituents Y, the dispersed phenolic resin reaction
product contains a mixture of oligomers having structures believed to be represented by
the following formula IH:
wherein X and Y ate the same as in formulae la and lb, a is 0 or 1; n is 0 to 5; R2 is
independently -C(R5)2- or -C(R3)2-0-C(R5)2-, wherein R3 is independently hydrogen,
alkylol, hydroxyl, alkyl, aryl or aryl ether; and R3 is independently alkylol, alkyl, aryl or
aryl ether. Preferably, R1 is methylene or oxydimethylene and R3 is methylol. If 6,7-
dihydroxy-2-naphthalenesulfonate, sodium salt is the modifying agent, X will be S03"Na+
and each Y will be OH. It should be recognized that in this case the hydroxy groups for
Y will also act as chelating groups with a metal ion.
The autodepositable component can be present in the composition in any amount
that provides for effective autodeposition. In general, the amount can range from 1 to 50,
preferably 5 to 20, and more preferably 7 to 14, weight percent, based on the total amount
of non-volatile ingredients in the composition.
The control agent is any material that is able to improve the formation of an
autodeposited coating on a metallic surface and, optionally, improve the formation of
another autodeposited coating applied after the control agent-containing autodeposited
coating. Addition of the control agent also increases the uniformity of the thickness of
the autodeposited coating. The control agent-containing composition does not require an
ambient staging period in order to develop fully the coating. In other words, the metallic
coating conversion is complete upon drying of the coated substrate and any subsequent
coating, primer or adhesive compositions can be applied immediately after coating and
drying of the control agent-containing composition. The control agent also must be
compatible with the other components of the composition under acidic conditions without
prematurely coagulating or destabilizing the composition.
The control agent may be a nitro compound, a nitroso compound, an oxime
compound, a nitrate compound, or a similar material. A mixture of control agents may be
used. Organic nitro compounds are the preferred control agents.
The organic nitro compound is any material that includes a nitro group (-N02)
bonded to an organic moiety. Preferably, the organic nitro compound is water soluble or,
if water insoluble, capable of being dispersed in water. Illustrative organic nitro
compounds include nitroguanidine; aromatic nitrosulfonates such as nitro or
dinitrobenzenesulfonate and the salts thereof such as sodium, potassium, amine or any
monovalent metal ion (particularly the sodium salt of 3,5-dinitrobenzenesulfonate);
Naphthol Yellow S; and picric acid (also known as trinitrophenol). Especially preferred
for commercial availability and regulatory reasons is a mixture of nitroguanidine and
sodium nitrobenzenesulfonate.
The amount of control agent(s) in a multi-component composition may vary,
particularly depending upon the amount of any acid in the composition. Preferably, the
amount is up to 20 weight %, more preferably up to 10 weight %, and most preferably 2
to 5 weight %, based on the total amount of non-volatile ingredients in the composition.
According to a preferred embodiment, the weight ratio of nitroguanidine to sodium
nitrobenzenesulfonate should range from 1:10 to 5:1.
The organic nitro compound typically is mixed into the composition in the form
of an aqueous solution or dispersion. For example, nitroguanidine is a solid at room
temperature and is dissolved in water prior to formulating into the composition.
The compositions of the invention may be prepared by any method known in the
ait, but are preferably prepared by combining and milling or shaking the ingredients and
water in ball-mill, sand-mill, ceramic bead-mill, steel-bead mill, high speed media-mill or
the like. It is preferred to add each component to the mixture in a liquid form such as an
aqueous dispersion.
The composition may be applied to a substrate surface by any conventional
method such as spraying, dipping, brushing, wiping, roll-coating (including reverse roll-
coating) or the like, after which the composition typically is permitted to dry. Although
conventional application methods can be used, the composition can be applied via
autodeposition. The phenolic resin dispersion (A) of composition of the invention
enables autodeposition of the composition on an electrochemically active metallic
surf ace. Autodepositable compositions usually are applied by dipping the metallic
substrate or part into a bath of the composition. The metal substrate can reside in the
metal treatment composition bath for an amount of time sufficient to deposit a uniform
film of desired thickness. Typically, the bath residence time is from about 5 to about 120
seconds, preferably about 10 to about 30 seconds, and occurs at room temperature. The
metal treatment composition when it is applied to the metal substrate should be
sufficiently acidic to cause reaction with the metal to liberate the metallic ions. Typically,
the pH of the metal treatment composition should be 1 to 4, preferably 1.5 to 2.5, when it
is applied to the metal substrate. The composition typically is applied to form a dry film
thickness of 1 to 15, preferably 4 to 10 lim.
After simple forced air drying of a metal surface coated with the control agent-
containing composition the metal surface can be immediately coated with another type of
composition. The coated metal substrate typically is dried by subjecting it to heat and
forced air. Depending upon the forced air flow, the drying usually occurs at
approximately 150-200°F for a time period ranging from 30 seconds to 10 minutes. The
ambient staging period previously required after such heated drying is no longer
necessary. However, immediate subsequent coating of the treated metal substrate is not
required. Alternatively, the treated metal substrate can be stored for a period of time and
then subsequently coated with a different composition.
Although not required since a phenolic is incorporated in the metal treatment
formulation itself, the metal treatment can be used in combination with a subsequent
coating of a phenolic primer as mentioned above. The combined metal treatment and
phenolic primer provides corrosion resistance comparable to phosphatizing and a
conventional phenolic primer.
Preferably, the metal treatment composition serves as a protective coating under
a subsequently applied functional autodepositable coating such as an adhesive primer or
covercoat, particularly an adhesive primer or covercoat that is useful for bonding an
elastomeric substrate to a metal substrate. A further advantage of the metal treatment is
that it can activate a metal surface for autodeposition of the subsequently applied coating,
primer or adhesive topcoat that may include a dispersed phenolic resin as described
above. Such a primer is described in more detail in co-pending, commonly assigned U.S.
Provisional Patent Application No. 60/072,779, incorporated herein by reference. In
addition to enhancing the corrosion resistance as explained above, autodeposition activity
of the subsequent coating over the control agent-containing metal treatment composition
is substantially increased according to the invention.
Although preferred, the adhesive primer or covercoat applied over the metal
treatment docs not have to be autodepositable. Conventional, non-autodepositable
primers or covercoats can be used with the metal treatment composition. Especially
useful are known elastomer-to-metal adhesive primers or covercoats such as those
described in U.S. Patents No. 3,258,388; 3,258,389; 4,119,587; 4,167,500; 4,483,962;
5,036,122; 5,093,203; 5,128,403; 5,200,455; 5,200,459; 5,268,404; 5,281,638; 5,300,555;
and 5,496,884. Elastomer-to-metal adhesive primers and covercoats are commercially
available from Lord Corporation.
The composition according to the invention also can be utilized by itself without
any subsequent coating with an autodepositable primer or adhesive. Curing via
crosslinking of the phenolic resin could occur through air oxidation or a surface activated
chelating mechanism.
The invention will be described in more detail by way of the following non-
limiting examples. The failure mechanism for the tested bond is expressed in terms of
percent. A high percent of rubber retained (R)on the metal coupon is desirable since this
indicates that the adhesive bond is stronger than the rubber itself. Rubber-cement failure
(RC) indicates the percentage of failure at the interface between the rubber and the
adhesive. Cement-metal failure (CM) indicates the percentage of failure at the interface
between the metal substrate and the adhesive.
For the boiling water test the bonded test assemblies or coupons were prepared
according to ASTM-D-429-B. The leading edge of each of the assemblies was stressed
by suspending a two kg weight on the overlapping rubber tail and the assembly was then
mounted in a fixture so that the rubber tail was at an approximately 90° angle to the plane
formed by the bonded interface. The stressed edge interface was exposed to boiling water
by immersing the coupon in boiling water for the indicated time period. After this time,
the coupons were removed from the boiling water, allowed to cool and tested on either an
Instron mechanical tester by pulling the rubber off the metal at a 45° angle stripping
fixture with a crosshead speed of 2 inches per minute or by manually peeling the rubber
from the metal substrate. The amount of rubber retained on the bonded area is recorded
as a percentage as described above.
For the salt spray test the bonded test assemblies prepared according to ASTM-D-
429-B were buffed on the edges with a grinding wheel. The rubber is then tied back over
the metal with stainless steel wire so as to stress the bonded area. This exposes the bond
line to the environment. The assemblies then are strung on stainless steel wire and placed
in a salt spray chamber. The environment inside the chamber is 100°F, 100 percent
relative humidity and 5 percent dissolved salt in the spray, which is dispersed throughout
the chamber. The assemblies remain in this environment for the indicated time period.
Upon removal, the rubber is peeled manually from the metal substrate. The amount of
rubber retained on the bonded area is recorded as a percentage as described above.
Example-1 - Preparation of Dispersed Novolak Resin
40 g of 6,7-dihydroxy-2-naphthalenesulfonatc (DHNS), sodium salt (available
from Andrew Chemicals), 136 g of a water soluble resole (made from formaldehyde and
phenol, F/P ratio of 2.3, 80% solids and commercially available from Schenectady under
the trade designation HRJ11722), 50 g of tert-butyl catechol and 50 g of water were
mixed together and steam heated for approximately three and one-half hours until the
mixture became very viscous. 220 g of resorcinol and 220 g of water were added
followed by 6 g of phosphoric acid in 20 g of water. Steam heating was continued for
another 40 minutes. 70 g of formalin then was added while continuing steam heating
resulting in a concentrate. The concentrate was filtered and self-dispersed upon the
addition of 1730 g of water.
Example-2 - Preparation of Dispersed Resole Resin
160 g of 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt (available from
Andrew Chemicals), 1000 g of the HRJ11722 water soluble resole, and 50 g of water
were mixed together and steam heated for approximately three hours resulting in a very
thick concentrate. 3600 g of water was added to the concentrate which then self-dispersed
and was filtered.
Example-3 - Preparation of Dispersed Novolak Resin
80 g of 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt (available from
Andrew Chemicals), 272 g of the HRJ11722 water soluble resin, 100 g of tert-butyl
catechol and 50 g of water were mixed together and steam heated for approximately three
and one-half hours until the mixture became very viscous. 440 g of resorcinol and 440 g
of water were added followed by 12 g of phosphoric acid in 25 g of water. Steam heating
was continued for another 40 minutes. 130 g of formalin then was added while
continuing steam heating resulting in a concentrate. The concentrate was filtered and
self-dispersed upon the addition of 3085 g of water.
Example-4 - Metal Treatment with Improved Bonding Performance
The following ingredients were mixed together in indicated wet weight grams to obtain a
metal treatment:
Aqueous novolak dispersion of Example 1 400 g
Phosphoric acid 34 o
Water 3100 g
The following ingredients were mixed together in indicated wet weight grams to obtain a
coating/primer:
Carbon black 7 g
ZnO 60 g
Aqueous resole dispersion of Example 2 125 g
Polyvinyl alcohol-stabilized resole (BKUA 2370) 200 g
Dichlorobutadiene homopolymer (VERSA TL/DOWFAX stabilized) 150 g
Water 300 g
The metal treatment was spray applied to one set of warm steel coupons. The treated
coupons were dried at 150°F. The dried treated coupons were heated for 10 minutes at
160°F and the coating/primer was spray applied. The coupons then were heated at 150°F
for 15 minutes. With another set of coupons only the coating/primer was spray applied.
A commercially available aqueous adhesive covercoat (CFfEMLOK®8210 available from
Lord Corporation) then was spray applied to the treated, primed coupons. Natural rubber
was injection molded to the coupons at 1 minute prebake and 5 minutes cure at 360°F.
The bonded test assemblies were subjected to the 40 hour boiling water test. The set of
coupons that were metal treated and primed exhibited a mean bonding performance of
93R, 7CM under and the set of that were only primed exhibited a mean bonding
performance of 47 R, 53 CM. When used in conjunction with CHEMLOK® 8210, the
metal treatment clearly improved the bonding performance of the coating/primer.
Kxample-5 - Autodcpositable Metal Treatment
The following ingredients were mixed together in indicated wet weight grams to obtain
an autodepositable coating/primer:
Carbon black 21 g
ZnO 180 g
Aqueous resole dispersion of Example 2 400 g
Polyvinyl alcohol-stabilized resole (BKUA 2370) 600 g
Dichlorobutadiene homopolymer (VERSA TL/DOWFAX stabilized) 450 g
Water 1000 g
The following ingredients were mixed together in indicated wet weight grams to obtain a
metal treatment used as an activator composition:
Aqueous novolak dispersion of Example 3 600 g
Phosphoric acid 400 g
Water 2700 g
Phosphatized steel coupons were dipped in a bath of the metal treatment composition (4%
solids) for 5 seconds. The metal treatment composition formed a continuous wet film on
the steel coupon surface indicating successful autodeposition. The treated coupons then
were dried at 150°F. The dried treated coupons were then dipped in a bath of the
coating/primer (20% solids) for 15 seconds. The coating/primer composition formed a
continuous wet film on the steel coupon surface indicating successful autodeposition. The
coated coupons then were dried for 15 minutes at 150°F. A one inch area then was
masked off and a commercially available aqueous adhesive covercoat
(CHEMLOK®8282 available from Lord Corporation) was spray applied onto the treated
and coated coupons. The coupons then were prebaked for 30 seconds at 360 °F prior to
bonding natural rubber for 5 minutes at 360 °F to the adhesive coated coupon. This
procedure was repeated, but the prebake was for 1 minute at 340 °F and bonding was for
7 and one-half minutes at 340 °F. The resulting test assemblies were subjected to the 4
hour boiling water test and the salt spray test (500, 750 and 1000 hours). The results for
all of the assemblies were 100%R bonding performance, no underbond corrosion and
very minor blistering in the unbonded portion that had been masked off.
Examples 6-14 - Metal Treatment that Includes Control Agent
Steel coupons (known as Q-Panels) were dipped in baths of the compositions at
room temperature for 15 seconds (for both 6% and 8% total solids content). After
immersion the treated coupons were immediately dried at 200°F for 5 minutes.
Immediately after drying the treated Q-panels were dipped for approximately 15 seconds
in an autodepositable primer composition. The autodepositable primer composition was
prepared by mixing together 18 g carbon black, 60 g zinc oxide, 75 g mica, 360 g aqueous
phenolic resole resin dispersion, 540 g phenolic resole aqueous dispersion that
incorporates a non-ionic protective colloid, presumably polyvinyl alcohol, (available from
Georgia-Pacific under the trade designation GP 4000), 600 g dichlorobutadiene
homopolymer latex and 2800 g water to form a composition having a solids content of
15%. The treated and primer-coated Q-panels then were dried at 200°F and then
subsequently baked for 15 minutes at 320°F. Autodeposited coatings had formed on all
the panels.
The resulting panels were placed in a salt spray chamber in which the
environment inside the chamber is 95°F, 100 percent relative humidity and 5 percent
dissolved salt in the spray, which is dispersed as a fog continuously throughout the
chamber. The panels were removed from the salt spray chamber after 300 hours and
flexed on a % inch mandrel. The crown of the flex was abraded by hand with
SCOTCHBRITE abrasive cleaning pads to determine the durability of the coating that
had been subjected to the corrosive salt spray testing. The rating scale was as follows: 0-
massive delamination on simple flexing, extending beyond flexed area; 1-delamination of
flexed area only; 2-some delamination on flexing, abrasion removed remaining coating in
WO 03/09*76 PCT/LSOJ/13617
55
flexed area; 3- cracking of the coating, coating readily removed on abrasion; 4-materia]
could be abraded off but otherwise appeared to well-adhered; 5-coating was unaffected by
flex and abrasion. The results are shown in Table 2.
Examples 15-17 - Metal Treatment that includes Control Agent
Aqueous metal treatment compositions according to the invention were prepared
by mixing together at room temperature the ingredients in the g wet weight amounts
shown below in Table 3. The aqueous phenolic resin dispersion was the novolak
dispersion described in connection with Examples 6-14.
Q-panels were dipped in baths of these compositions for the amount of time and
temperature shown in Table 4 ("RT" represents room temperature) and then subjected to
drying at 200°F, except for the 15 second dip of Example 16 that was not dried. The
treated panels then were immediately dipped in a bath of the autodepositable primer
composition described in Examples 6-14 for approximately 10 seconds, dried at 200°F
and then baked for 15 minutes at 320°F. With respect to the one sample wherein the
metal treatment was not dried, application of the primer was done on a wet surface.
Autodeposited coatings had formed on each panel. The resulting panels then were
subjected to the salt spray testing for 250, 500 and 750 hours. After removal from the salt
spray chamber, the Q-panels were evaluated according to three tests. First, a portion of
the panels was abraded by hand with a SCOTCHBRITE pad and the percentage amount
of coating surface area that was unaffected was recorded. Second, a final portion of the
panels was flexed on a 5/16 inch mandrel and then the crown of the flex was subjected to
the pencil scratch test. The results of these tests are displayed in Table 4. With respect to
the flex test, "very poor" is massive flaking, "poor" is visible flaking, "fair" is no flaking,
but poor scratch on flexed areas.
Table 4
Examples 18-20-Metal Treatment with Various Flexibilizers
Aqueous metal treatment compositions according to the invention were prepared
by mixing together at room temperature the following ingredients in g wet weight
amounts: 360 g aqueous novolak dispersion described in connection with Examples 6-
14; 360 g phosphoric acid; 950 g water; 152 g dinitrobenzene sulfonate (free acid); and
72 g flexibilizer. The flexibilizer in Example 18 was a styrene-butadiene rubber emulsion
commercially available from Reichold Chemical Co. under the tradename TYLAC
97924; Example 19 was a chlorosulfonated polyethylene latex commercially available
from Lord Corporation under the tradename HYP 605; and Example 20 was a chlorinated
natural rubber latex.
Q-panels and degreased cold-rolled steel coupons were dipped for ten seconds in
the metal treatment composition (8% solids) of each Example and then forced air dried at
200°F. The treated Q-panels and coupons then were immediately dipped for 10 seconds
in the autodepositable primer described above in connection with Examples 6-14. The Q-
panels and coupons then were dried for five minutes at 200°F and then baked for 15
minutes at 32()°F.
The resulting Q-panels were placed in the salt spray chamber for 250 hours. After
removal from the salt spray chamber the Q-panels were abraded with SCOTCHBRITE
pads and the percentage of coating not removed is indicated below in Table 5 under the
heading "250 hrs SS". The Q-panels were also flexed on a 5/16 inch mandrel. The
crown of the flex was abraded by hand with SCOTCHBRITE abrasive cleaning pads to
determine the durability of the coating that had been subjected to the corrosive salt spray
testing. The percentage of coaling not removed across the flexed radius is indicated
below in Table 5.
A commercially available aqueous adhesive covercoat (CHEMLOK®82S2
available from Lord Corporation) was spray applied onto the treated and coated coupons
only. The coupons then were prebaked for 5 minutes at 300 °F prior to bonding natural
rubber for 16.5 minutes at 320 °F to the adhesive coated coupon via compression
molding. The bonded coupons were tested for primary adhesion performance (according
to ASTM 429B) as described above and the results are shown below in Table 5. The
bonded coupons also were flexed over a 1 inch mandrel, the rubber was peeled back by
WO 03/093376 PCT/US03/13617
58
hand and the percentage of rubber retained on the crown of the flex is indicated in Table
5.
Table 5
Examples 21-23 -Metal Treatment with Novolaks Made From Different Modifying
Agents
200 g of resorcinol, 20 g of pyrogallol, 12 g of phosphoric acid (855 aqueous
solution) and 220 g of water were mixed together and heated to 95°C. When 95°C was
reached, 250 g of formalin (18.5% aqueous solution) was fed to the reaction mixture over
a period of 30 minutes. Steam heating was continued for another 15 minutes at which
point the mixture was slightly turbid and had a low viscosity (a sample precipitated out of
solution upon dilution with water). 32 g of 2-formylbenzenesulfonic acid (sodium salt,
75% moist solid) and 40 more g of formalin then were added. After one hour and 15
minutes of steam heating the resin was very viscous. 580 g of water was added to the
resin mixture and steam heating was continued until the resin was completely dispersible.
Using essentially the same procedure 5-formyl-2-furan sulfonate and l-diazo-2-naphthol-
4-sulfonate stabilized (i.e., substituted for 2-formylbenzenesulfonic acid)
resorcinol/pyrogallol novolak aqueous dispersions were prepared.
Three different metal treatment compositions (each containing one of the different
novolak dispersions) were made by mixing together the following ingredients in wet
weight amounts: 180 g dispersed novolak resin; 180 g phosphoric acid; 475 g water; 76 g
dinitrobenzene sulfonate; and 36 g HYCAR latex. Q-panels were dipped into a bath of
the metal treatment, dried for 3 minutes at 200°F, and then immediately dipped for ten
seconds into a bath of the primer composition described in Examples 6-14. After
removal from the primer bath, the Q-panels were dried at 200°F, and baked for fifteen
minutes at 320°F. The resulting Q-panels had coatings varying in thickness from 0.90 to
1.06 mils indicating the formation of an autodeposited coating. The coated Q-panels
were placed in the salt spray chamber for 250 and 500 hours, respectively. The Q-panel
coatings were abraded with a SCOTCHBRTTE pad and the percentage of coating not
removed is indicated below in Table 6.
We Claim:
1. An aqueous metal surface treatment composition comprising the
following ingredients:
(A) an aqueous dispersion of a phenolic resin that includes a reaction
product of
(i) a phenolic resin precursor such as herein described;
(ii) a modifying agent, comprising a hydrocarbyl moiety bonded to
at least one functional moiety that enables the modifying agent
to react with the phenolic resin precursor; and at least one ionic
moiety comprising an ionizable group containing sulfur or
phosphorus,
(iii) at least one multi-hydroxyphenolic compound; such as herein
described; and
(B) optionally an acid, wherein (iii) is optional in (A) when said reaction
product (A) contains two or more reactive phenolic methylol groups.
2. The composition as claimed in claim 1, wherein the ionizable group is
selected from the group consisting of sulfonate (-S(0)2H,) and salt (-
S(0)20"M+), sulfinate (-S(O)OH) and salt (-S(0)0"M+), sulfenate (-
SOH) and salt (-SCnvT), phosphono, -P(0)(OH)2 and salts (-
P(0)(OH)0-M+ and (-P(0)(0)22'Mi+M2+); phosphono ester (-
P(0)(OH)(OR)) and salt (-P(0)(Or)CHvl+); phosphonomethyl, (-
CH2P(0)(OH)2) and salts (-CH2P(0)(OH)0-M+) and (-CH2P(0)(0)22-
M1+M2+);
phosphino, (-P(0)(OH)) and salt (-P(0)0"M+); and phosphinomethyl (-
CH2P(0)(OH)) and salt (-CH2P(0)OM+); wherein M+ can be any
monovalent cation.
3. The composition as claimed in claim 1, wherein the ionic moiety
comprises sulfur.
4. The composition as claimed in claim 1, wherein the ionic moiety
comprises phosphorous.
5. The composition as claimed in claim 1, wherein the ionic moiety
comprises sulfur.
\6. The composition as claimed in claim 1, wherein the ionic moiety
' comprises phosphorous.
7. An aqueous metal surface treatment composition according to claim 1, further
comprising an acid.
8. The composition according to claim 1, wherein the hydrocarbyl moiety of said
modifying agent is a substituted or unsubstituted C,-C20 aliphatic group.
9. The composition according to claim 6, wherein the modifying agent is

10. The composition according to claim 6, wherein the modifying is

11. The composition according to claim 2, wherein the ionic moiety comprises a
sulfinate (-S(O)OH).
12. The composition according to claim 2, wherein the ionic moiety comprises a
sulfonate group represented by -S.(0)2OH or -S(0)20'M\ wherein M* represents a
monovalent cation.
13. The composition according to claim 2, wherein the ionic moiety comprises a
sulfinate (-S(0)0']vf), wherein M* represents a monovalent cation.
14. The composition according to claim 2, wherein the ionic moiety comprises a
sulfenate group represented by -SOH or -SOTvf, wherein M* represents a monovalent
cation.
15. The composition according to claim 5, wherein the modifying agent is
16. The composition according to claim 5, wherein the ionic moiety comprises a
sulfonomethylgroup represented by -CH,S(0),OH or -CHjSCOXO "M\ wherein MT
represents a monovalent cation.
17. The composition according to claim 1, wherein the reaction enabling moiety of the
modifying agent is a formyl group.
18. The composition according to claim 1, wherein the modifying agent contains a
nitrogen group.
19. The composition according to claim 18, wherein the nitrogen group is selected from
the group consisting of an amide-, imine-, amine-, urea-, amidine-, guanidine-,
semicarbazide-, hydrazide-, thiohydrazide-, fhioamide-, thiourea-, thiosemicarbazide-,
carbamate-, thiocarbamate-, dithiocarbamate-, and isothiourea -containing group.
20. The composition according to claim 17, wherein the modifying agent is an aliphatic
formyl compound, and wherein the ionic moiety comprises a sulfonate group represented
by -S(0),OH or -S(0),0 "M\ wherein M* represents a monovalent ion.
21. The composition according to claim 18, wherein the modifying agent is a nitrogen-
containing compound, and wherein the ionic moiety comprises a sulfonate group
represented by -S(0)2OH or -S(0),0'M\ wherein M* represents a monovalent ion.
22. The composition according to claim 5, wherein the modifying agent is selected from
wherein R and R' are H or C,-C10 substituted or unsubstituted, linear or branch alkyl
groups, C6-C30 aryl, and C