METHOD OF MAKING A FLAME RETARDANT POLY(ARYLENE
ETHER)/POLYAMIDE COMPOSITION AND THE COMPOSITION THEREOF
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. Patent Application No. 10/994,769
filed on November 22, 2004, which is herein incorporated by reference in its entirety.
BACKGROUND OF INVENTION
Poly(arylene ether) resins have been blended with polyamide resins to provide
compositions having a wide variety of beneficial properties such as heat resistance,
chemical resistance, impact strength, hydrolytic stability and dimensional stability.
These beneficial properties are desirable in a wide variety of applications and the
shapes and sizes of the parts required for these applications vary widely. As a result
there is a variety of forming or molding methods employed such as injection molding,
compression molding and extrusion. Each molding method requires a different set of
physical characteristics for the polymer being molded. A polymer blend that is
suitable for high shear/high pressure processes such as injection molding may not be
suitable for low pressure/low shear processes such as blow molding, sheet extrusion
and profile extrusion. For example, profile extrusion requires that a polymer blend be
forced through a shaped die (a profile) and maintain the extruded shape until cooled.
The extruded shape may be further manipulated while the polymer blend is still
malleable through the use of shaping tools and the shaped profile must retain its shape
after manipulation. Therefore polymer blends employed in low pressure/low shear
processes typically have fairly high melt viscosity (low melt flow indices) as well as
high melt strength.
In some applications it is desirable that the extruded shape be electrostatically
coatable which requires use of an electrically conductive material. Unfortunately the
inclusion of electrically conductive additives in high melt viscosity blends can be
problematic, particularly in a multi phase polymer blends such as a poly(arylene
ether)/polyamide blend. Furthermore, flame retardancy of electrically conductive
high melt viscosity blends can be difficult to achieve.
Similarly flame retardance of reinforced thermoplastic compositions can .be difficult
to achieve as the presence of the reinforcing filler alters the combustion behavior of
the composition compared to non-reinforced compositions.
BRIEF DESCRIPTION OF THE INVENTION
The foregoing need is addressed by a composition comprising a poly(arylene ether), a
polyamide, electrically conductive additive, an impact modifier, and a phosphinate.
In another embodiment, a method of making a composition comprises:
melt mixing a first mixture comprising a'poly(arylene ether) and a compatibilizing
agent to form a first melt mixture;
melt mixing a second mixture comprising the first melt mixture and a polyamide,
electrically conductive additive and a flame retardant masterbatch wherein the flame
retardant masterbatch comprises a phosphinate and a thermoplastic resin.
In another embodiment, a reinforced composition comprises a poly(arylene ether), a
polyamide, a reinforcing filler, a phosphinate, and an optional impact modifier. The
composition may further comprise an electrically conductive additive. As used
herein, a reinforced composition is a composition comprising a reinforcing filler.
In another embodiment, a method of making a composition comprises:
melt mixing a poly(arylene ether), a compatibilizing agent, a polyamide, a reinforcing
filler, and a flame retardant masterbatch wherein the flame retardant masterbatch
comprises a phosphinate and a thermoplastic resin.
DETAILED DESCRIPTION
As mentioned above low pressure/low shear molding processes require materials with
melt strength sufficiently high and a melt volume rate (MVR) sufficiently low to
maintain the desired shape after leaving the extrusion die or mold. Additionally it is
desirable for the materials to be sufficiently electrically conductive to permit
electrostatic coating and have a flame retardancy rating of V-l or better according to
Underwriter's Laboratory Bulletin 94 entitled "Tests for Flammability of Plastic
Materials, UL94" (UL94) at a thickness of 2.0 millimeters (mm). Reinforced
compositions have a flame retardancy rating of V-l or better according to
Underwriter's Laboratory Bulletin 94 entitled "Tests for Flammability of Plastic
Materials, UL94" (UL94) at a thickness of 1.5 millimeters (mm).
In one embodiment, a composition useful in low pressure/low shear molding
processes comprises a poly(arylene ether), a polyamide, an impact modifier,
electrically conductive additive, and a phosphinate. The melt volume rate of the
composition is compatible with low pressure/low shear processes. In one
embodiment the composition has a melt volume rate less than or equal to 25 cubic
centimeters (cc)/10min, or, more specifically, less than or equal to 20 cc/lOmin, or,
even more specifically, less than or equal to 16 cc/lOmin, as determined by Melt
Volume Rate test ISO 1133 performed at 300°C with a load of 5 kilograms (kg).
The composition may have a Vicat B120 greater than or equal to 170°C, or, more
specifically, greater than or equal to 180°C, or, even more specifically, greater than or
equal to 190°C. Vicat B120 is determined using ISO 306 standards. A Vicat B120
greater than or equal to 170°C ensures that the composition has adequate heat
performance for electrostatic coating.
Specific volume resistivity (SVR) is a measure of the leakage current directly through
a material. It is defined as the electrical resistance through a one-centimeter cube of
material and is expressed in ohm-cm. The lower the specific volume resistivity of a
material, the more conductive the material is. In one embodiment the composition has
a specific volume resistivity less than or equal to 10* ohm-cm, or, more specifically,
less than or equal to 105, or, even more specifically, less than or equal to 104. Specific
volume resistivity may be determined as described in the Examples. Surprisingly the
inclusion of the phosphinate reduces the resistivity relative to a comparable
composition lacking phosphinate. As a result it is possible to achieve the same or
lower resistivity in a composition comprising phosphinate and electrically conductive
additive than a composition comprising electrically conductive additive without
phosphinate.
In some embodiments it may be advantageous for the composition to have a volatiles
content sufficiently low to prevent or limit the amount of build up on the molding
equipment.
Articles made of a composition comprising a poly(arylene ether), a polyamide,
reinforcing filler, a phosphinate, an optional impact modifier and an optional
electrically conductive additive show low warpage and excellent fire retardance.
The terms "a" and "an" herein do not denote a limitation of quantity, but rather denote
the presence of at least one of the referenced item. All ranges disclosed herein are
inclusive and combinable (e.g., ranges of "less than or equal to 25 wt%, or, more
specifically, 5 wt% to 20 wt%," is inclusive of the endpoints and all intermediate
values of the ranges of "5 wt% to 25 wt%," etc.).
As used herein, a "poly(arylene ether)" comprises a plurality of structural units of the
formula (1):
(Figure Removed)
wherein for each structural unit, each Q1 and each Q2 is independently hydrogen,
halogen, primary or secondary lower alkyl (e.g., an alkyl containing 1 to 7 carbon
atoms), phenyl, haloalkyl, aminoalkyl, alkenylalkyl, alkynylalkyl, aryl,
hydrocarbonoxy, and halohydrocarbonoxy wherein at least two carbon atoms separate
the halogen and oxygen atoms. In some embodiments, each Q1 is independently alkyl
or phenyl, for example, C1-4 alkyl, and each Q2 is independently hydrogen or methyl.
The poly(arylene ether) may comprise molecules having aminoalkyl-containing end
group(s), typically located in an ortho position to the hydroxy group. Also frequently
present are tetramethy) diphenylquinone (TMDQ) end groups, typically obtained from
reaction mixtures in which tetramethyl diphenylquinone by-product is present.
The poly(arylene ether) may be in the form of a homopolymer; a copolymer; a graft
copolymer; an ionomer; a block copolymer, for example comprising arylene ether
units and blocks derived from alkenyl aromatic compounds; as well as combinations
comprising at least one of the foregoing. Poly(arylene ether) includes polyphenylene
ether comprising 2,6-dimethyl-l,4-phenylene ether units optionally in combination
with 2,3,6-trimethyl-l,4-phenylene ether units.
The poly(arylene ether) may be prepared by the oxidative coupling of
monohydroxyaromatic compound(s) such as 2,6-xylenol and/or 2,3,6-
trimethylphenol. Catalyst systems are generally employed for such coupling; they can
contain heavy metal compound(s) such as a copper, manganese or cobalt compound,
usually in combination with various other materials such as a secondary amine,
tertiary amine, halide or combination of two or more of the foregoing.
The poly(arylene ether) can have a number average molecular weight of 3,000 to
40,000 grams per mole (g/mol) and/or a weight average molecular weight of about
5,000 to about 80,000 g/mol, as determined by gel permeation chromatography using
monodisperse polystyrene standards, a styrene divinyl benzene gel at 40°C and
samples having a concentration of 1 milligram per milliliter of chloroform. The
poly(arylene ether) can have an initial intrinsic viscosity of 0.10 to 0.60 deciliters per
gram (dl/g), or, more specifically, 0.29 to 0.48 dl/g, as measured in chloroform at
25°C. Initial intrinsic viscosity is defined as the intrinsic viscosity of the poly(arylene
ether) prior to melt mixing with the other components of the composition and final
intrinsic viscosity is defined as the intrinsic viscosity of the poly(arylene ether) after
melt mixing with the other components of the composition. As understood by one of
ordinary skill in the art the viscosity of the poly(arylene ether) may be up to 30%
higher after melt mixing. The percentage of increase can be calculated by (final
intrinsic viscosity - initial intrinsic viscosity)/initial intrinsic viscosity. Determining
an exact ratio, when two initial intrinsic viscosities are used, will depend somewhat on
the exact intrinsic viscosities of the poly(arylene ether) used and the ultimate physical
properties that are desired.
In one embodiment the poly(arylene ether) has a glass transition temperature (Tg) as
determined by differential scanning calorimetry (DSC at 20°C/minute ramp), of 160°C
to 250°C. Within this range the Tg may be greater than or equal to 180°C, or, more
specifically, greater than or equal to 200°C. Also within this range the Tg may be less
than or equal to 240°C, or, more specifically, less than or equal to 230°C.
The composition comprises poly(arylene ether) in an amount of 15 to 65 weight
percent. Within this range, the poly(arylene ether) may be present in an amount
greater than or equal to 30 weight percent, or, more specifically, in an amount greater
than or equal to 35 weight percent, or, even more specifically, in an amount greater
than or equal to 40 weight percent. Also within this range the poly(arylene ether) may
be present in an amount less than or equal to 60 weight percent, or, more specifically,
less than or equal to 55 weight percent, or, even more specifically, less than or equal
to 50 weight percent. Weight percent is based on the total weight of the thermoplastic
composition.
Polyamide resins, also known as nylons, are characterized by the presence of an amide
group (-C(O)NH-), and are described in U.S. Patent No. 4,970,272. Exemplary
polyamide resins include, but are not limited to, nylon-6; nylon-6,6; nylon-4; nylon-
4,6; nylon-12; nylon-6,10; nylon 6,9; nylon-6,12; amorphous polyamide resins; nylon
6/6T and nylon 6.6/6T with triamine contents below 0.5 weight percent; nylon 9T;
and combinations of two or more of the foregoing polyamides. In one embodiment,
the polyamide resin comprises nylon 6 and nylon 6,6. In one embodiment the
polyamide resin or combination of polyamide resins has a melting point (Tm) greater
than or equal to 171°C. When the polyamide comprises a super tough polyamide, i.e.
a rubber-toughed polyamide, the composition may or may hot contain a separate
impact modifier.
Polyamide resins may be obtained by a number of well known processes such as those
described in U.S. Patent Nos. 2,071,250; 2,071,251; 2,130,523; 2,130,948; 2,241,322;
2,312,966; and 2,512,606. Polyamide resins are commercially available from a wide
variety of sources.
Polyamide resins having an intrinsic viscosity of up to 400 milliliters per gram (ml/g)
can be used, or, more specifically, having a viscosity of 90 to 350 ml/g, or, even more
specifically, having a viscosity of 110 to 240 ml/g, as measured in a 0.5 wt% solution
in 96 wt% sulfuric acid in accordance with ISO 307.
The polyamide may have a relative viscosity of up to 6, or, more specifically, a
relative viscosity of 1.89 to 5.43, or, even more specifically, a relative viscosity of
2.16 to 3.93. Relative viscosity is determined according to DIN 53727 in a 1 wt%
solution in 96 wt% sulfuric acid.
In one embodiment, the polyamide resin comprises a polyamide having an amine end
group concentration greater than or equal to 35 microequivalents amine end group per
gram of polyamide (ueq/g) as determined by titration with HC1. Within this range, the
amine end group concentration may be greater than or equal to 40 ueq/g, or, more
specifically, greater than or equal to 45 ueq/g. Amine end group content may be
determined by dissolving the polyamide in a suitable solvent, optionally with heat.
The polyamide solution is titrated with 0.01 Normal hydrochloric acid (HC1) solution
using a suitable indication method. The amount of amine end groups is calculated
based the volume of HC1 solution added to the sample, the volume of HC1 used for the
blank, the molarity of the HC1 solution and the weight of the polyamide sample.
In one embodiment, the polyamide comprises greater than or equal to 50 weight
percent, based on the total weight of the polyamide, of a polyamide having a melt
temperature within 35%, or more specifically within 25%, or, even more specifically,
within 15% of the glass transition temperature (Tg) of the poly(arylene ether). As
used herein having a melt temperature within 35% of the glass transition temperature
of the polyarylene ether is defined as having a melt temperature that is greater than or
equal to (0.65 X Tg of the poly(arylene ether)) and less than or equal to (1.35 X Tg of
the poly(arylene ether)).
The composition comprises polyamide in an amount of 30 to 85 weight percent.
Within this range, the polyamide may be present in an amount greater than or equal to
33 weight percent, or, more specifically, in an amount greater than or equal to 38
weight percent, or, even more specifically, in an amount greater than or equal to 40
weight percent. Also within this range, the polyamide may be present in an amount
less than or equal to 60 weight percent, or, more specifically, less than or equal to 55
weight percent, or, even more specifically, less than or equal to 50 weight percent.
Weight percent is based on the total weight of the thermoplastic composition
When used herein, the expression "compatibilizing agent" refers to polyfunctional
compounds which interact with the poly(arylene ether), the polyamide resin, or both.
This interaction may be chemical (e.g., grafting) and/or physical (e.g., affecting the
surface characteristics of the dispersed phases). In either instance the resulting
compatibilized poly(arylene ether)/polyamide composition appears to exhibit
improved compatibility, particularly as evidenced by enhanced impact strength, mold
knit line strength and/or elongation. As used herein, the expression "compatibilized
poly(arylene ether)/polyamide blend" refers to those compositions which have been
physically and/or chemically compatibilized with an agent as discussed above, as well
as those compositions which are physically compatible without such agents, as taught
in U.S. Pat. No. 3,379,792.
Examples of the various compatibilizing agents that may be employed include: liquid
diene polymers, epoxy compounds, oxidized polyolefin wax, quinones, organosilane
compounds, polyfunctional compounds, functionalized poly(arylene ether) and
combinations comprising at least one of the foregoing. Compatibilizing agents are
further described in U.S. Patent Nos. 5,132,365 and 6,593,411 as well as U.S. Patent
Application No. 2003/0166762.
In one embodiment, the compatibilizing agent comprises a polyfunctional compound.
Polyfunctional compounds which may be employed as a compatibilizing agent are of
three types. The first type of polyfunctional compounds are those having in the
molecule both (a) a carbon-carbon double bond or a carbon-carbon triple bond and (b)
at least one carboxylic acid, anhydride, amide, ester, imide, amino, epoxy, orthoester,
or hydroxy group. Examples of such polyfunctional compounds include maleic acid;
maleic anhydride; fumaric acid; glycidyl acrylate, itaconic acid; aconitic acid;
maleimide; maleic hydrazide; reaction products resulting from a diamine and maleic
anhydride, maleic acid, fumaric acid, etc.; dichloro maleic anhydride; maleic acid
amide; unsaturated dicarboxylic acids (e.g., acrylic acid, butenoic acid, methacrylic
acid, t-ethylacrylic acid, pentenoic acid, decenoic acids, undecenoic acids, dodecenoic
acids, linoleic acid, etc.); esters, acid amides or anhydrides of the foregoing
unsaturated carboxylic acids; unsaturated alcohols (e.g. alky] alcohol, crotyl alcohol,
methyl vinyl carbinol, 4-pentene-l-ol, l,4-hexadiene-3-ol, 3-butene- 1,4-diol, 2,5-
dimethyl-3-hexene-2,5-diol and alcohols of the formula CnH2n . ,OH, CnH2n . ,OH and
CnH2n . 9OH, wherein n is a positive integer less than or equal to 30); unsaturated
amines resulting from replacing from replacing the -OH group(s) of the above
unsaturated alcohols with NH2 groups; functionalized diene polymers and copolymers;
and combinations comprising one or more of the foregoing. In one embodiment, the
compatibilizing agent comprises maleic anhydride and/or fumaric acid.
The second type of polyfunctional compatibilizing agents are characterized as having
both (a) a group represented by the formula (OR) wherein R is hydrogen or an alkyl,
aryl, acyl or carbonyl dioxy group and (b) at least two groups each of which may be
the same or different selected from carboxylic acid, acid halide, anhydride, acid halide
anhydride, ester, orthoester, amide, imido, amino, and various salts thereof. Typical
of this group of compatibilizers are the aliphatic polycarboxylic acids, acid esters and
acid amides represented by the formula:
wherein R is a linear or branched chain, saturated aliphatic hydrocarbon having 2 to
20, or, more specifically, 2 to 10, carbon atoms; R1 is hydrogen or an alkyl, aryl, acyl,
or carbonyl dioxy group having 1 to 1 0, or, more specifically, 1 to 6, or, even more
specifically, 1 to 4 carbon atoms; each R" is independently hydrogen or an alkyl or
aryl group having 1 to 20, or, more specifically, 1 to 10 carbon atoms; each R1" and
RIV are independently hydrogen or an alkyl or aryl group having 1 to 10, or, more
specifically, 1 to 6, or, even more specifically, 1 to 4, carbon atoms; m is equal to 1
and (n + s) is greater than or equal to 2, or, more specifically, equal to 2 or 3, and n
and s are each greater than or equal to zero and wherein (OR1) is alpha or beta to a
carbonyl group and at least two carbonyl groups are separated by 2 to 6 carbon atoms.
Obviously, R', R", R1", and RIV cannot be aryl when the respective substituent has less
than 6 carbon atoms.
Suitable polycarboxylic acids include, for example, citric acid, malic acid, agaricic
acid; including the various commercial forms thereof, such as for example, the
anhydrous and hydrated acids; and combinations comprising one or more of the
foregoing. In one embodiment, the compatibilizing agent comprises citric acid.
Illustrative of esters useful herein include, for example, acetyl citrate, mono- and/or
distearyl citrates, and the like. Suitable amides useful herein include, for example,
N,N'-diethyl citric acid amide; N-phenyl citric acid amide; N-dodecyl citric acid
amide; N,N'-didodecyl citric acid amide; and N-dodecyl malic acid. Derivates include
the salts thereof, including the salts with amines and the alkali and alkaline metal
salts. Exemplary of suitable salts include calcium malate, calcium citrate, potassium
malate, and potassium citrate.
The third type of polyfunctional compatibilizing agents are characterized as having in
the molecule both (a) an acid halide group and (b) at least one carboxylic acid,
anhydride, ester, epoxy, orthoester, or amide group, preferably a carboxylic acid or
anhydride group. Examples of compatibilizers within this group include trimellitic
anhydride acid chloride, chloroformyl succinic anhydride, chloro formyl succinic
acid, chloroformyl glutaric anhydride, chloroformyl glutaric acid, chloroacetyl
succinic anhydride, chloroacetylsuccinic acid, trimellitic acid chloride, and
chloroacetyl glutaric acid. In one embodiment, the compatibilizing agent comprises
trimellitic anhydride acid chloride.
Some polyamides require particular types of compatibilizing agents. For example,
monomeric compatibilizing agents or monomeric compatibilizing agents reacted with
poly(arylene ether) are useful with nylon 9T but polymeric compatibilizing agents are
generally unsuccessful.
The foregoing compatibilizing agents may be added directly to the melt blend or prereacted
with either or both of the poly(arylene ether) and polyamide, as well as with
other resinous materials employed in the preparation of the composition. With many
of the foregoing compatibilizing agents, particularly the poly functional compounds,
even greater improvement in compatibility is found when at least a portion of the
compatibilizing agent is pre-reacted, either in the melt or in a solution of a suitable
solvent, with all or a part of the poly(arylene ether). It is believed that such prereacting
may cause the compatibilizing agent to react with the polymer and,
consequently, functionalize the poly(arylene ether). For example, the poly(arylene
ether) may be pre-reacted with maleic anhydride to form an anhydride functionalized
poly(arylene ether) which has improved compatibility with the polyamide compared
to a non-functionalized poly(arylene ether).
Where the compatibilizing agent is employed in the preparation of the compositions,
the amount used will be dependent upon the specific compatibilizing agent chosen and
the specific polymeric system to which it is added.
Impact modifiers can be block copolymers containing alkenyl aromatic repeating
units, for example, A-B diblock copolymers and A-B-A triblock copolymers having
of one or two alkenyl aromatic blocks A (blocks having alkenyl aromatic repeating
units), which are typically styrene blocks, and a rubber block, B, which is typically an
isoprene or butadiene block. The butadiene block may be partially or completely
hydrogenated. Mixtures of these diblock and triblock copolymers may also be used
as well as mixtures of non-hydrogenated copolymers, partially hydrogenated
copolymers, fully hydrogenated copolymers, radial teleblock copolymers, tapered
block copolymers, and combinations of two or more of the foregoing.
A-B and A-B-A copolymers include, but are not limited to, polystyrenepolybutadiene,
polystyrene-poly(ethylene-propylene), polysryrene-polyisoprene,
poly(ct-methylstyrene)-polybutadiene, polystyrene-polybutadiene-polystyrene (SBS),
polystyrene-poly(ethylene-propylene)-polystyrene, polystyrene-polyisoprenepolystyrene
and poly(alpha-methylstyrene)-polybutadiene-poly(alpha-methylstyrene),
polystyrene-poly(ethylene-propylene-styrene)-polystyrene, and the like. Mixtures of
the aforementioned block copolymers are also useful. Such A-B and A-B-A block
copolymers are available commercially from a number of sources, including Phillips
Petroleum under the trademark SOLPRENE, Kraton Polymers, under the trademark
KRATON, Dexco under the trademark VECTOR, Asahi Kasai under the trademark
TUFTEC, Total Petrochemicals under the trademarks FINAPRENE and
FINACLEAR, Kuraray under the trademark SEPTON, and Chevron Phillips
Chemical Company under the tradename K-RESIN.
In one embodiment, the impact modifier comprises polystyrene-poly(ethylenebutylene)-
polystyrene, polystyrene-poly(ethylene-propylene) or a combination of the
foregoing.
Another type of impact modifier is essentially free of alkenyl aromatic repeating units
and comprises one or more moieties selected from the group consisting of carboxylic
acid, anhydride, epoxy, oxazoline, and orthoester. Essentially free is defined as
having alkenyl aromatic units present in an amount less than 5 weight percent, or,
more specifically, less than 3 weight percent, or, even more specifically less than 2
weight percent, based on the total weight of the block copolymer. When the impact
modifier comprises a carboxylic acid moiety the carboxylic acid moiety may be
neutralized with an ion, preferably a metal ion such as zinc or sodium. It may be an
alkylene-alkyl (meth)acrylate copolymer and the alkylene groups may have 2 to 6
carbon atoms and the alkyl group of the alkyl (meth)acrylate may have 1 to 8 carbon
atoms. This type of polymer can be prepared by copolymerizing an olefin, for
example, ethylene and propylene, with various (meth)acrylate monomers and/or
various maleic-based monomers. The term (meth)acrylate refers to both the acrylate
as well as the corresponding methacrylate analogue. Included within the term
(meth)acrylate monomers are alkyl (meth)acrylate monomers as well as various
(meth)acrylate monomers containing at least one of the aforementioned reactive
moieties.
In a one embodiment, the copolymer is derived from ethylene, propylene, or mixtures
of ethylene and propylene, as the alkylene component; butyl acrylate, hexyl acrylate,
or propyl acrylate as well as the corresponding alkyl (methyl)acrylates, for the alkyl
(meth)acrylate monomer component, with acrylic acid, maleic anhydride, glycidyl
methacrylate or a combination thereof as monomers providing the additional reactive
moieties (i.e., carboxylic acid, anhydride, epoxy).
Exemplary first impact modifiers are commercially available from a variety of
sources including ELVALOY PTW, SURLYN, and FUSABOND, all of which are
available from DuPont.
The aforementioned impact modifiers can be used singly or in combination.
The composition may comprise an impact modifier or a combination of impact
modifiers, in an amount of 1 to 15 weight percent. Within this range, the impact
modifier may be present in an amount greater than or equal to 1.5 weight percent, or,
more specifically, in an amount greater than or equal to 2 weight percent, or, even
more specifically, in an amount greater than or equal to 4 weight percent. Also within
this range, the impact modifier may be present in an amount less than or equal to 13
weight percent, or, more specifically, less than or equal to 12 weight percent, or, even
more specifically, less than or equal to 10 weight percent. Weight percent is based on
the total weight of the thermoplastic composition.
The composition may optionally further comprise a rubber-modified poly(alkenyl
aromatic) resin. A rubber-modified poly(alkenyl aromatic) resin comprises a polymer
denved from at least one of the alkenyl aromatic monomers described above, and
further comprises a rubber modifier in the form of a blend and/or a graft. The rubber
modifier may be a polymerization product of at least one C4-CIO nonaromatic diene
monomer, such as butadiene or isoprene. The rubber-modified poly(alkeny) aromatic)
resin comprises about 98 to about 70 weight percent of the poly(alkenyl aromatic)
resin and about 2 to about 30 weight percent of the rubber modifier, preferably about
88 to about 94 weight percent of the poly(alkenyl aromatic) resin and about 6 to about
12 weight percent of the rubber modifier.
Exemplary rubber-modified poly(alkenyl aromatic) resins include the styrenebutadiene
copolymers containing about 88 to about 94 weight percent styrene and
about 6 to about 12 weight percent butadiene. These styrene-butadiene copolymers,
also known as high-impact polystyrenes, are commercially available as, for example,
GEH 1897 from General Electric Company, and BA 5350 from Chevron Chemical
Company
The composition may comprise the rubber-modified poly(alkenyl aromatic) resin in
an amount up to 25 weight percent, or, more specifically up to 20 weight percent, or,
even more specifically, up to 18 weight percent, based on the total weight of the
composition.
The electrically conductive additive may comprise electrically conductive carbon
black, carbon nanotubes, carbon fibers or a combination of two or more of the
foregoing. Electrically conductive carbon blacks are commercially available and are
sold under a variety of trade names, including but not limited to S.C.F. (Super
Conductive Furnace), E.C.F. (Electric Conductive Furnace), Ketjen Black EC
(available from Akzo Co., Ltd.) or acetylene black. In some embodiments the
electrically conductive carbon black has an average particle size less than or equal to
200 nanometers (ran), or, more specifically, less than or equal to 100 nm, or, even
more specifically, less than or equal to 50 nm. The electrically conductive carbon
blacks may also have surface areas greater than 200 square meter per gram (m2/g), or,
more specifically, greater than 400 mVg, or, even more specifically, greater than 1000
mVg, The electrically conductive carbon black may have a pore volume greater than
or equal to 40 cubic centimeters per hundred grams (cm3/lOOg), or, more specifically,
greater than or equal to 100 cm3/lOOg, or, even more specifically, greater than or equal
to 150 cm3/l OOg, as determined by dibutyl phthalate absorption.
Carbon nanotubes that can be used include single wall carbon nanotubes (SWNTs),
multiwall carbon nanotubes (MWNTs), vapor grown carbon fibers (VGCF) and
combinations comprising two or more of the foregoing. Carbon nanotubes can also be
considered to be reinforcing filler.
Single wall carbon nanotubes (SWNTs) may be produced by laser-evaporation of
graphite, carbon arc synthesis or a high-pressure carbon monoxide conversion process
(H1PCO) process. These SWNTs generally have a single wall comprising a graphene
sheet with outer diameters of 0.7 to 2.4 nanometers (nm). The SWNTs may comprise
a mixture of metallic SWNTs and semi-conducting SWNTs. Metallic SWNTs are
those that display electrical characteristics similar to metals, while the semiconducting
SWNTs are those that are electrically semi-conducting. In some
embodiments it is desirable to have the composition comprise as large a fraction of.
metallic SWNTs as possible. SWNTs may have aspect ratios of greater than or equal
to 5, or, more specifically, greater than or equal to 100, or, even more specifically,
greater than or equal to 1000. While the SWNTs are generally closed structures
having hemispherical caps at each end of the respective tubes, it is envisioned that
SWNTs having a single open end or both open ends may also be used. The SWNTs
generally comprise a central portion, which is hollow, but may be filled with
amorphous carbon.
In one embodiment the SWNTs comprise metallic nanotubes in an amount of greater
than or equal to 1 wt%, or, more specifically, greater than or equal to 20 wt%, or,
more specifically, greater than or equal to 30 wt%, or, even more specifically greater
than or equal to 50 wt%, or, even more specifically, greater than or equal to 99.9 wt%
of the total weight of the SWNTs.
In one embodiment the SWNTs comprise semi-conducting nanotubes in an amount of
greater than or equal to 1 wt%, or, more specifically, greater than or equal to 20 wt%,
or, more specifically, greater than or equal to 30 wt%, or, even more specifically,
greater than or equal to 50 wt%, or, even more specifically, greater than or equal to
99.9 wt% of the total weight of the SWNTs.
MWNTs may be produced by processes such as laser ablation and carbon arc
synthesis. MWNTs have at least two graphene layers bound around an inner hollow
core. Hemispherical caps generally close both ends of the MWNTs, but it is also
possible to use MWNTs having only one hemispherical cap or MWNTs which are
devoid of both caps. MWNTs generally have diameters of 2 to 50 nm. Within this
range, the MWNTs may have an average diameter less than or equal to 40, or, more
specifically, less than or equal to 30, or/even more specifically less than or equal to
20 nm. MWNTs may have an average aspect ratio greater than or equal to 5, or, more
specifically, greater than or equal to 100, or, even more specifically greater than or
equal to 1000.
Vapor grown carbon fibers (VGCF) are generally manufactured in a chemical vapor
deposition process. VGCF having "tree-ring" or "fishbone" structures may be grown
from hydrocarbons in the vapor phase, in the presence of particulate metal catalysts at
moderate temperatures, i.e., 800 to 1500°C. In the "tree-ring" structure a multiplicity
of substantially graphitic sheets are coaxially arranged about the core. In the
"fishbone" structure, the fibers are characterized by graphite layers extending from the
axis of the hollow core.
VGCF having diameters of 3.5 to 2000 nanometers (nm) and aspect ratios greater than
or equal to 5 may be used. VGCF may have diameters of 3.5 to 500 nm, or, more
specifically 3.5 to 100 nm, or, even more specifically 3.5 to 50 nm. VGCF may have
an average aspect ratios greater than or equal to 100, or, more specifically, greater
than or equal to 1000.
Various types of conductive carbon fibers may also be used in the composition.
Carbon fibers are generally classified according to their diameter, morphology, and
degree of graphitization (morphology and degree of graphitization being interrelated).
These characteristics are presently determined by the method used to synthesize the
carbon fiber. For example, carbon fibers having diameters down to 5 micrometers,
and graphene ribbons parallel to the fiber axis (in radial, planar, or circumferential
arrangements) are produced commercially by pyrolysis of organic precursors in
fibrous form, including phenolics, polyacrylonitrile (PAN), or pitch.
The carbon fibers generally have a diameter of greater than or equal to 1,000
nanometers (1 micrometer) to 30 micrometers. Within this range fibers having sizes
of greater than or equal to 2, or, more specifically, greater than or equal to 3, or, more
specifically greater than or equal to 4 micrometers may be used. Also within this
range fibers having diameters of less than or equal to 25, or, more specifically, less
than or equal to 15, or, even more specifically less than or equal to 11 micrometers
may be used.
The composition comprises a sufficient amount of electrically conductive additive to
achieve a specific volume resistivity less than or equal to 10' ohm-cm. For example,
the composition may comprise electrically conductive carbon black and/or carbon
fibers and/or carbon nanotubes in an amount of 1 to 20 weight percent. Within this
range, the electrically conductive additive may be present in an amount greater than or
equal to 1.2 weight percent, or, more specifically, in an amount greater than or equal
to 1.4 weight percent, or, even more specifically, in an amount greater than or equal to
1.6 weight percent. Also within this range, the electrically conductive carbon filler
may be present in an amount less than or equal to 15 weight percent, or, more
specifically, less than or equal to 10 weight percent, or, even more specifically, less
than or equal to 5 weight percent. Weight percent is based on the total weight of the
thermoplastic composition.
It is interesting to note that the amount of electrically conductive additive required to
achieve a particular level of conductivity is highly dependent upon the electrically
conductive additive. For instance, compositions comprising MWNT or VGCF in
amounts of 1 to 1.2 weight percent, based on the total weight of the composition, have
electrical conductivity commensurate with the electrical conductivity of compositions
comprising conductive carbon black in an amount greater than 1.7 weight percent,
based on the total weight of the composition. The difference in the amounts of
electrically conductive additive can have a significant impact on physical properties
such as flammability, impact strength and tensile elongation.
In some embodiments it is desirable to incorporate a sufficient amount of electrically
conductive additive to achieve a specific volume resistivity that is sufficient to permit
the composition to dissipate electrostatic charges or to be thermally dissipative.
Reinforcing fillers are fillers that can improve dimensional stability by lowering the
coefficient of thermal expansion. They also increase the flexural and tensile modulus,
reduce warpage or a combination thereof of the reinforced composition when
compared to an analogous composition free of reinforcing filler.
Non-limiting examples of reinforcing fillers include silica powder, such as fused silica
and crystalline silica; boron-nitride powder and boron-silicate powders; alumina, and
magnesium oxide (or magnesia); wollastonite including surface-treated wollastonite;
calcium sulfate (as its anhydride, dihydrate or trihydrate); calcium carbonate including
chalk, limestone, marble and synthetic, precipitated calcium carbonates, generally in
the form of a ground particulates; talc, including fibrous, modular, needle shaped, and
lamellar talc; glass spheres, both hollow and solid; kaolin, including hard, soft,
calcined kaolin, and kaolin comprising various coatings known in the art to facilitate
compatibility with the polymeric matrix resin; mica; feldspar; silicate spheres; flue
dust; cenospheres; fillite; aluminosilicate (armospheres); natural silica sand; quartz;
quartzite; perlite; tripoli; diatomaceous earth; synthetic silica; and combinations
thereof. All of the above fillers may be surface treated with silanes to improve
adhesion and dispersion with the polymeric matrix resin.
Additional exemplary reinforcing fillers include flaked fillers that offer reinforcement
such as glass flakes, flaked silicon carbide, aluminum diboride, aluminum flakes, and
steel flakes. Exemplary reinforcing fillers also include fibrous fillers such as short
inorganic fibers, natural fibrous fillers, single crystal fibers, glass fibers, and organic
reinforcing fibrous fillers. Short inorganic fibers include those derived from blends
comprising at least one of aluminum silicates, aluminum oxides, magnesium oxides,
and calcium sulfate hemihydrate. Natural fibrous fillers include wood flour obtained
by pulverizing wood, and fibrous products such as cellulose, cotton, sisal, jute, starch,
cork flour, lignin, ground nut shells, corn, rice grain husks. Single crystal fibers or
"whiskers" include silicon carbide, alumina, boron carbide, iron, nickel, and copper
single crystal fibers. Glass fibers, including textile glass fibers such as E, A, C, ECR,
R, S, D, and NE glasses and quartz, and the like may also be used. In addition,
organic reinforcing fibrous fillers may also be used including organic polymers
capable of forming fibers. Illustrative examples of such organic fibrous fillers
include, for example, poly(ether ketone), polyimide, polybenzoxazole, poly(phenylene
sulfide), polyesters, polyethylene, aromatic polyamides, aromatic polyimides or
polyetherimides, polytetrafluoroethylene, acrylic resins, and poly(vinyl alcohol).
Such reinforcing fillers may be provided in the form of monofilament or
multifilament fibers and can be used either alone or in combination with other types of
fiber, through, for example, co-weaving or core/sheath, side-by-side, orange-type or
matrix and fibril constructions, or by other methods known to one skilled in the art of
fiber manufacture. Typical cowoven structures include glass fiber-carbon fiber,
carbon fiber-aromatic polyimide (aramid) fiber, and aromatic polyimide fiber-glass
fiber. Fibrous fillers may be supplied in the form of, for example, rovings, woven
fibrous reinforcements, such as 0-90 degree fabrics, non-woven fibrous
reinforcements such as continuous strand mat, chopped strand mat, tissues, papers and
felts and 3-dimensionally woven reinforcements, performs and braids.
In one embodiment the reinforcing filler comprises talc. The talc may have an
average particle size of 3 micrometers.
The reinforcing filler, when part of the composition, is present in an amount of 5 to 30
weight percent with respect to the total weight of poly(arylene ether), polyamide,
phosphinate, reinforcing filler, optional impact modifier, and optional electrically
conductive additive. Within this range the reinforcing filler may be present in an
amount greater than or equal to 10 weight percent, or, more specifically, greater than
or equal to 15 weight percent. Also within this range the reinforcing filler may be
present in an amount less than or equal to 25 weight percent, or, more specifically,
less than or equal to 20 weight percent.
The phosphinate may comprise one or more phosphinates of formula II, III, or IV
(Figure Removed)
wherein R1 and R2 are independently C1-C6 alkyl, phenyl, or aryl; R3 is independently
C1-CIO alkylene, C6-C10 arylene, C6-CIO alkylarylene, or C6-C10 arylalkylene; M is
calcium, magnesium, aluminum, zinc or a combination comprising one or more of the
foregoing; d is 2 or 3; f is 1 or 3; x is 1 or 2; each R" and R5 are independently a
hydrogen group or a vinyl group of the formula -CR7=CHR8; R7 and R8 are
independently hydrogen, carboxyl, carboxylic acid derivative, C1-CIO alkyl, phenyl,
benzyl, or an aromatic substituted with a C1-C8 alkyl; K is independently hydrogen or
a 1/r metal of valency r and u, the average number of monomer units, may have a
value of 1 to 20.
Examples of R' and R2 include, but are not limited to, methyl, ethyl, n-propyl,
isopropyl, n-butyl, tert-butyl, n-pentyl, and phenyl. Examples of R3 include, but are
not limited to, methylene, ethylene, n-propylene, isopropylene, n-butylene, tertbutylene,
n-pentylene, n-octylene, n-dodecylene, phenylene, naphthylene,
methylphenylene, ethylphenylene, tert-butylphenylene, methylnapthylene,
ethylnapthylene, tert-butylnaphthylene, phenylethylene, phenylpropylene, and
phenylbutylene.
The mono- and diphosphinates (formulas II and III respectively) may be prepared by
reacting the corresponding phosphinic acid with a metal oxide and/or metal hydroxide
in an aqueous medium as taught in EP 0 699 708.
The polymeric phosphinates (formula IV) may be prepared by reacting
hypophosphorous acid and or its alkali metal salt with an acetylene of formula (V)
R7 r.=c R8
The resulting polymeric phosphinic acid or polymeric phosphinic acid salt is then
reacted with a metal compound of groups 1A, IIA, 1IIA, 1VA, VA, IIB, IVB, VIIB,
V1IIB of the Periodic Table as taught in U.S. Patent Application No. 2003/0216533.
In one embodiment, R1 and R2 are ethyl.
In one embodiment the phosphinate is in paniculate form. The phosphinate particles
may have a median particle diameter (D50) less than or equal to 40 micrometers, or,
\more specifically, a D50 less than or equal to 30 micrometers, or, even more
specifically, a D50 less than or equal to 25 micrometers. Additionally, the
phosphinate may be combined with a polymer, such as a poly(arylene ether), a
polyolefin, a polyamide, and/or an impact modifier, to form a masterbatch. The
phosphinate masterbatch comprises the phosphinate in an amount greater than is
present in the thermoplastic composition. Employing a masterbatch for the addition
of the phosphinate to the other components of the composition can facilitate addition
and improve distribution of the phosphinate.
The composition comprises an amount of phosphinate sufficient to achieve a flame
retardance of V-l or better at a thickness of 2.0 millimeters according to UL94. In
one embodiment the composition comprises an amount of phosphinate sufficient to
achieve a flame retardance of V-0 at a thickness of 2.0 millimeters according to UL94.
For example, the composition may comprise phosphinate in an amount of 5 to 25
weight percent. Within this range, the phosphinate may be present in an amount
greater than or equal to 7 weight percent, or, more specifically, in an amount greater
than or equal to 8 weight percent, or, even more specifically, in an amount greater
than or equal to 9 weight percent. Also within this range the phosphinate may be
present in an amount less than or equal to 22 weight percent, or, more specifically,
less than or equal to 17 weight percent, or, even more specifically, less than or equal
to 15 weight percent. Weight percent is based on the total weight of the thermoplastic
composition.
In one embodiment, the reinforced composition comprises an amount of phosphinate
sufficient to achieve a flame retardance of V-l or better at a thickness of 1.5
millimeters according to UL94. In one embodiment the reinforced composition
comprises an amount of phosphinate sufficient to achieve a flame retardance of V-0 at
a thickness of 1.5 millimeters according to UL94. For example, the reinforced
composition may comprise phosphinate in an amount of 5 to 25 weight percent.
Within this range, the phosphinate may be present in an amount greater than or equal
to 7 weight percent, or, more specifically, in an amount greater than or equal to 8
weight percent, or, even more specifically, in an amount greater than or equal to 9
weight percent. Also within this range the phosphinate may be present in an amount
less than or equal to 22 weight percent, or, more specifically, less than or equal to 17
weight percent, or, even more specifically, less than or equal to 15 weight percent.
Weight percent is based on the total weight of the thermoplastic composition.
The composition may optionally comprise an inorganic compound such as an oxygen
compound of silicon, a magnesium compound, a metal carbonate of metals of the
second main group of the periodic table, red phosphorus, a zinc compound, an
aluminum compound or a composition comprising one or more of the foregoing. The
oxygen compounds of silicon can be salts or esters of orthosilicic acid and
condensation products thereof; silicates; zeolites; silicas; glass powders; glass-ceramic
powders; ceramic powders; or combinations comprising one or more of the foregoing
oxygen compound of silicon. The magnesium compounds can be magnesium
hydroxide, hydrotalcites, magnesium carbonates or magnesium calcium carbonates or
a combination comprising one or more of the foregoing magnesium compounds. The
red phosphorus can be elemental red phosphorus or a preparation in which the surface
of the phosphorus has been coated with low-molecular-weight liquid substances, such
as silicone oil, paraffin oil or esters of phthalic acid or adipic acid, or with polymeric
or oligomeric compounds, e.g., with phenolic resins or amino plastics, or else with
polyurethanes. The zinc compounds can be zinc oxide, zinc stannate, zinc
hydroxystannate, zinc phosphate, zinc borate, zinc sulfides or a composition
comprising one of more of the foregoing zinc compounds. The aluminum compounds
can be aluminum hydroxide, aluminum phosphate, or a combination thereof.
In one embodiment, the inorganic compound comprises zinc borate.
The composition may optionally comprise a nitrogen compound or combination of
nitrogen compounds. Exemplary nitrogen compounds include those having the
formulas (VI) to (XI):
(Figure Removed)
wherein R9 to R" are independently hydrogen; C1 -Cg -alkyl; C5 -CI6 -cycloalkyl
unsubstituted or substituted with a hydroxy) function or with a C, -C4 -hydroxyalkyl
function; C5 -C16-alkylcycloalkyl, unsubstituted or substituted with a hydroxyl
function or with a C, -C4 -hydroxyalkyl function; C2 -C8 -alkenyl; C2 -C8 -alkoxy; C2 -
Cs -acyl; C2 -C8 -acyloxy; C6 -C12 -aryl; C6 -C,2 -arylalkyl; -OR20; -N(R20)R12; Nalicyclic;
N-aromatic systems;
R20 is hydrogen; C, -C, -alkyl; C5 -C16 -cycloalkyl, unsubstituted or substituted with a
hydroxyl function or with a C, -C4 -hydroxyalkyl function; C5 -C16 -alkylcycloalkyl,
unsubstituted or substituted with a hydroxyl function or with a C, -C, -hydroxyalkyl
function; C2 -C8 -alkenyl; C, -CR -alkoxy; C, -C, -acyl; C, -C8 -acyloxy; C6 -C12 -aryl;
or C6 -CI2 -arylalkyl;
R12 to R16 are groups identical with R20 or else -O-R20,
g and h, independently of one another, are 1, 2, 3 or 4,
G is the residue of an acid which can form an adduct with triazine compounds (VI).
The nitrogen compound may also be an ester of tris(hydroxyethyl) isocyanurate with
aromatic polycarboxylic acids, a nitrogen-containing phosphate of the formula (NH4)y
H3.y PO4 or (1MH, PO,)Z, where y is from 1 to 3 and z is from 1 to 10,000 or a
combination comprising one or more of the foregoing nitrogen compounds.
Exemplary nitrogen compounds include melamine polyphosphate, melem phosphate,
melam phosphate, melamine pyrophosphate, melamine, melamine cyanurate,
combinations comprising one or more of the foregoing, and the like.
The composition can be prepared melt mixing or a combination of dry blending and
melt mixing. Melt mixing can be performed in single or twin screw type extruders or
similar mixing devices which can apply a shear to the components.
All of the ingredients may be added initially to the processing system. In some
embodiments, the poly(arylene ether) may be precompounded with the
compatibilizing agent. Additionally other ingredients such as an impact modifier,
phosphinate, optional synthetic inorganic compound, optional nitrogen compound,
and a portion of the polyamide may be precompounded with the compatibilizing
agent and poly(arylene ether). In one embodiment, the poly(arylene ether) is
precompounded with the compatibilizing agent to form a functionalized poly(arylene
ether). The functionalized poly(arylene ether) is then compounded with the other
ingredients. In another embodiment the poly(arylene ether), compatibilizing agent,
impact modifier, phosphinate, optional synthetic inorganic compound, and optional
nitrogen compound are compounded to form a first material and the polyamide is
then compounded with the first material. The phosphinate, optional synthetic
inorganic compound and optional nitrogen compound may be added as a masterbatch.
When using an extruder, all or part of the polyamide may be fed through a port
downstream. While separate extruders may be used in the processing, preparations in
a single extruder having multiple feed ports along its length to accommodate the
addition of the various components simplifies the process. It is often advantageous to
apply a vacuum to the melt through one or more vent ports in the extruder to remove
volatile impurities in the composition.
The electrically conductive filler may be added by itself, with other ingredients
(optionally as a dry blend) or as part of a masterbatch. In one embodiment, the
electrically conductive filler can be part of a masterbatch comprising polyamide. The
electrically conductive filler may be added with the poly(arylene ether), with the
polyamide (the second portion when two portions are employed), or after the addition
of the polyamide (the second portion when two portions are employed).
In one embodiment, the phosphinate is combined with a thermoplastic resin to form a
flame retardant masterbatch. The masterbatch is used to form the composition. In
one embodiment the thermoplastic resin used to form the masterbatch is a polyamide
or a resin miscible with the polyamide. The resin has sufficiently low viscosity to
blend with the phosphinate. The masterbatch may also comprise the optional
inorganic compound, the optional nitrogen compound or a combination of the
optional inorganic compound and the optional nitrogen compound. The masterbatch
may comprise 20 to 80 weight percent phosphinate and 20 to 80 weight percent
thermoplastic resin with respect to the combined weight of phosphinate and
thermoplastic resin. Within this range the phosphinate may be present in the
masterbatch in an amount greater than or equal to 25 weight percent, or, more
specifically, greater than or equal to 30 weight percent. Also within this range the
phosphinate may be present in the masterbatch in an amount less than or equai to 75
weight percent, or, more specifically, less than or equal to 70 weight percent.
In one embodiment, the poly(arylene ether) and compatibilizing agent, such as maleic
anhydride, are melt mixed to form a first melt mixture and isolated in a particulate
form. A second mixture comprising the particulate first melt mixture and optionally a
portion of polyamide is then melt mixed to form a second melt mixture that is further
melt mixed with polyamide, the flame retardant masterbatch, and electrically
conductive additive. The optional inorganic compound and the optional nitrogen
compound may be added independently or together at any point or they may be part
of the flame retardant masterbatch. The impact modifier may be part of the second
melt mixture or be added after the formation of the second melt mixture. When the
composition comprises two impact modifiers they can be added together or
separately.
In one embodiment, the poly(arylene ether), compatibilizing agent and optionally a
portion of polyamide is melt mixed to form a first melt mixture that is further melt
mixed with polyamide, the flame retardant masterbatch, and electrically conductive
additive. The optional inorganic compound and the optional nitrogen compound may
be added independently or together at any point or they may be part of the flame
retardant masterbatch. The impact modifier may be part of the first melt mixture or
be added after the formation of the first melt mixture. When the composition
comprises two impact modifiers they can be added together or separately.
In one embodiment, the poly(arylene ether) and compatibilizing agent are melt mixed
to form a first melt mixture and isolated in a particulate form. A second mixture
comprising the particulate first melt mixture, flame retardant masterbatch, and
optionally a portion of polyamide is then melt mixed to form a second melt mixture
that is further melt mixed with polyamide, and reinforcing filler. The optional
inorganic compound and the optional nitrogen compound may be added
independently or together at any point or they may be part of the flame retardant
masterbatch. The impact modifier may be part of the second melt mixture or be
added after the formation of the second melt mixture. When the composition
comprises two impact modifiers they can be added together or separately.
In one embodiment, the poly(arylene ether) and compatibilizing agent are melt mixed
to form a first melt mixture and isolated in a particulate form. A second mixture
comprising the particulate first melt mixture, and optionally a portion of polyamide is
then melt mixed to form a second melt mixture that is further melt mixed with
polyamide, flame retardant masterbatch, and reinforcing filler. The optional
inorganic compound may be added at any point. The optional nitrogen compound
may be added at any point. The optional inorganic compound, optional nitrogen
compound or both can be added with the flame retardant masterbatch or can be part of
the flame retardant masterbatch. The impact modifier may be part of the second melt
mixture or be added after the formation of the second melt mixture. When the
composition comprises two impact modifiers they can be added together or
separately.
In one embodiment, the poly(arylene ether), compatibilizing agent, flame retardant
masterbatch, and optionally a portion of polyamide is melt mixed to form a first melt
mixture that is further melt mixed with polyamide and reinforcing filler. The optional
inorganic compound may be added at any point. The optional nitrogen compound
may be added at any point. The optional inorganic compound, optional nitrogen
compound or both can be added with the flame retardant masterbatch or can be part of
the flame retardant masterbatch. The impact modifier may be part of the first melt
mixture or be added after the formation of the first melt mixture. When the
composition comprises two impact modifiers they can be added together or
separately.
In one embodiment, the poly(arylene ether), compatibilizing agent, and optionally a
portion of polyamide is melt mixed to form a first melt mixture that is further melt
mixed with polyamide, flame retardant masterbatch, and reinforcing filler. The
optional inorganic compound may be added at any point. The optional nitrogen
compound may be added at any point. The optional inorganic compound, optional
nitrogen compound or both can be added with the flame retardant masterbatch or can
be part of the flame retardant masterbatch. The impact modifier may be part of the
first melt mixture or be added after the formation of the first melt mixture. When the
composition comprises two impact modifiers they can be added together or
separately.
While separate extruders may be used in the processing, preparations in a single
extruder having multiple feed ports along its length to accommodate the addition of
the various components simplifies the process. It is often advantageous to apply a
vacuum to the melt through one or more vent ports in the extruder to remove volatile
impurities in the composition.
The electrically conductive additive may be added by itself, with other ingredients
(optionally as a dry blend) or as part of a masterbatch. In one embodiment, the
electrically conductive additive can be part of a masterbatch comprising polyamide.
The electrically conductive additive may be added with the poly(arylene ether), with
the polyamide (the second portion when two portions are employed), or after the
addition of the polyamide (the second portion when two portions are employed). The
electrically conductive additive may be part of the fire retardant masterbatch.
In one embodiment the composition comprises the reaction product of poly(arylene
ether); polyamide; electrically conductive additive; compatibilizing agent; impact
modifier; and phosphinate. As used herein a reaction product is defined as the
product resulting from the reaction of two or more of the foregoing components under
the conditions employed to form the composition, for example during compounding
or high shear mixing.
In one embodiment the composition comprises the reaction product of poly(arylene
ether); polyamide; reinforcing filler, optional electrically conductive additive;
compatibilizing agent; optional impact modifier; and phosphinate. As used herein a
reaction product is defined as the product resulting from the reaction of two or more
of the foregoing components under the conditions employed to form the composition,
for example during melt mixing or high shear mixing.
After the composition is melt mixed it is typically formed into strands which are cut
to form pellets. The strand diameter and the pellet length are typically chosen to
prevent or reduce the production of fines (particles that have a volume less than or
equal to 50% of the pellet) and for maximum efficiency in subsequent processing
such as profile extrusion. An exemplary pellet length is 1 to 5 millimeters and an
exemplary pellet diameter is 1 to 5 millimeters.
The pellets may exhibit hygroscopic properties. Once water is absorbed it may be
difficult to remove. Typically drying is employed but extended drying can affect the
performance of the composition. Similarly water, above 0.01-0.1%, or, more
specifically, 0,02-0.07% moisture by weight, can hinder the use of the composition in
some applications. It is advantageous to protect the composition from ambient
moisture. In one embodiment the pellets, once cooled to a temperature of 50°C to
110°C, are packaged in a container comprising a monolayer of polypropylene resin
free of a metal layer wherein the container has a wall thickness of 0.25 millimeters to
0.60 millimeters. The pellets, once cooled to 50 to 110°C can also be packaged in
foiled lined containers such as foil lined boxes and foil lined bags.
The composition may be converted to articles using low shear thermoplastic
processes such as film and sheet extrusion, profile extrusion, extrusion molding,
compression molding and blow molding. Film and sheet extrusion processes may
include and are not limited to melt casting, blown film extrusion and calendaring. Coextrusion
and lamination processes may be employed to form composite multi-layer
films or isheets. Single or multiple layers of coatings may further be applied to the
single or multi-layer substrates to impart additional properties such as scratch
resistance, ultra violet light resistance, aesthetic appeal, etc. Coatings may be applied
through standard application techniques such as powder coating, rolling, spraying,
dipping, brushing, or flow-coating.
Oriented films may be prepared through blown film extrusion or by stretching cast or
calendared films in the vicinity of the thermal deformation temperature using
conventional stretching techniques. For instance, a radial stretching pantograph may
be employed for multi-axial simultaneous stretching; an x-y direction stretching
pantograph can be used to simultaneously or sequentially stretch in the planar x-y
directions. Equipment with sequential uniaxial stretching sections can also be used to
achieve uniaxial and biaxial stretching, such as a machine equipped with a section of
differential speed rolls for stretching in the machine direction and a tenter frame
section for stretching in the transverse direction.
The compositions may be converted to multiwall sheet comprising a first sheet
having a first side and a second side, wherein the first sheet comprises a thermoplastic
polymer, and wherein the first side of the first sheet is disposed upon a first side of a
plurality of ribs; and a second sheet having a first side and a second side, wherein the
second sheet comprises a thermoplastic polymer, wherein the first side of the second
sheet is disposed upon a second side of the plurality of ribs, and wherein the first side
of the plurality of ribs is opposed to the second side of the plurality of ribs.
The films and sheets described above may further be thermoplastically processed into
shaped articles via forming and molding processes including but not limited to
thermoforming, vacuum forming, pressure forming, injection molding and
compression molding. Multi-layered shaped articles may also be formed by injection
molding a thermoplastic resin onto a single or multi-layer film or sheet substrate as
described below:
1. Providing a single or multi-layer thermoplastic substrate having optionally
one or more colors on the surface, for instance, using screen printing or a transfer
dye
2. Conforming the substrate to a mold configuration such as by forming and
trimming a substrate into a three dimensional shape and fitting the substrate into a
mold having a surface which matches the three dimensional shape of the substrate.
3. Injecting a thermoplastic resin into the mold cavity behind the substrate to (i)
produce a one-piece permanently bonded three-dimensional product or (ii) transfer a
pattern or aesthetic effect from a printed substrate to the injected resin and remove the
printed substrate, thus imparting the aesthetic effect to the molded resin.
Those skilled in the art will also appreciate that common curing and surface
modification processes including and not limited to heat-setting, texturing, embossing,
corona treatment, flame treatment, plasma treatment and vacuum deposition may
further be applied to the above articles to alter surface appearances and impart
additional functionalities to the articles.
Accordingly, another embodiment relates to articles, sheets and films prepared from
the compositions above.
Exemplary articles include all or portions of the following articles: furniture,
partitions, containers, vehicle interiors including rail cars, subway cars, busses, trolley
cars, airplanes, automobiles, and recreational vehicles, exterior vehicle accessories
such as roof rails, appliances, cookware, electronics, analytical equipment, window
frames, wire conduit, flooring, infant furniture and equipment, telecommunications
equipment, antistatic packaging for electronics equipment and parts, health care
articles such as hospital beds and dentist chairs, exercise equipment, motor covers,
display covers, business equipment parts and covers, light covers, signage, air
handling equipment and covers, automotive underhood parts.
In one embodiment the composition is extruded to form an article with a desired
shape. The article can then be powder coated or painted if desired. Examples of such
articles include caps for cubicle partitions, furniture parts, groove tiles (covered tracks
for network wiring), conduits for electrical wires and the like.
In some embodiments it is important for the article formed from the composition to
exhibit very little or no warpage when exposed to elevated temperatures. For
example, a part can be formed, measured at points most likely to demonstrate
deformation and then aged at 160-190°C for 3 or more hours. After aging, the part is
measured again at the same points. If all of the measured points after aging are
within 10% or less of the same measured points before aging then the part exhibits
substantially no warpage.
The following non-limiting examples further illustrate the various embodiments
described herein.
EXAMPLES
The following examples used the materials shown in Table 1. Weight percent, as used
in the examples, is determined based on the total weight of the composition unless
otherwise noted.
32
Table 1.
(Table Removed)
Examples 1-7 and Comparative Examples 1-11
PPE, 0.1 weight percent (wt%) potassium iodide, 0.05 wt% copper iodide, 0.3 wt
% Irganox 1076 commercially available from Ciba-Geigy, 0.6 wt% citric acid, and
the nylon 6,6 were melt mixed to form a mixture. The mixture was rurthsr melt
mixed with nylon 6 and a masterbatch of electrically conductive carbon black in
nylon 6. In compositions containing Exolit OP 1312, SF, BP, TPP, RDP, MC or a
combination of two or more of the foregoing, these materials were added with the
polyphenylene ether at the feedthroat. The compositions were molded into bars
having a thickness of 2.0 millimeters for flammability testing. Flammability tests
were performed following the procedure of Underwriter's Laboratory Bulletin 94
entitled "Tests for Flammability of Plastic Materials, UL94". Each bar that
extinguished was ignited twice. According to this procedure, the materials were
classified as VO, VI or V2 on the basis of the test results obtained for ten samples.
If more than 3 of the first 5 bars had a burn time >30 seconds, then the burning
was stopped at 5 bars. The criteria for each of these flammability classifications
according to UL94, are, briefly, as follows.
VO: In a sample placed so that its long axis is parallel to the flame, the average period
of flaming and/or smoldering after removing the igniting flame should not exceed ten
seconds and none of the vertically placed samples should produce drips of burning
particles which ignite absorbent cotton. For five bars, the total burn time, including
all first burns and all second burns should not exceed 50 seconds.
VI: In a sample placed so that its long axis is parallel to the flame, the average period
of flaming and/or smoldering after removing the igniting flame should not exceed
thirty seconds and none of the vertically placed samples should produce drips of
burning particles which ignite absorbent cotton. For five bars, the total burn time,
including all first burns and all second bums should not exceed 250 seconds.
V2: In a sample placed so that its long axis is parallel to the flame, the average period
of flaming and/or smoldering after removing the igniting flame should not exceed
thirty seconds and the vertically placed samples produce drips of burning particles
which ignite cotton. For five bars, the total burn time, including all first bums and all
second burns should not exceed 250 seconds.
Results are shown in Table 2. Flame out time (FOT) is the-average of the sum of the
amounts of time the bar burned each time it was lit. "NA" in the-UL94 rating column
means that the sample did not fall within the parameters of any of the UL94 ratings.
Some examples were tested for specific volume resistivity (SVR). The compositions
were molded into ISO tensile bars. The bars were scored at two points along the
"neck" portion of the tensile bar at a distance of approximately 6.35 centimeters apart
and then submerged in liquid nitrogen for approximately 5 minutes. As soon as the
bars were removed from the liquid nitrogen they were snapped at the score marks.
The ends were painted with electrically conductive silver paint and dried. Resistance
was measured by placing the probes of a handheld multimeter (Fluke 187, True RMS
Multimeter set to resistance) on each painted end of the bar. The resistivity was
calculated as the resistance (in Ohms) X bar width (in centimeters (cm)) X bar depth
(cm) divided by the bar length (cm). Results are shown in Table 2. Comparative
examples are noted as CE and examples are Ex.
Melt Volume rate was determined according to ISO 1133. Vicat B was determined
according to ISO 306.
Table 2.
(Table Removed)
Comparative Examples 1 -5 demonstrate flame retardance behavior of several blends
that do not contain electrically conductive carbon black. Comparative Example 1
shows a generic compatibilized polyamide/poly(arylene ether) blend. No flame
retarding additives were present. The flame retardance is poor, with an average flame
out time (FOT) per bar greater than 100 seconds. Other well known flame retardants
were added in similar loadings in Comparative Examples 2 through 5. Comparative
Example 2 with melamine cyanurate and Comparative Example 3 with resorcinol
diphosphate both had average FOT greater than 100 seconds. Comparative Example
4, with triphenylphosphate, had an average FOT of 23.5 seconds, which begins to
approach V-l performance. However several of the individual bum times were longer
than 30 seconds and therefore the material received no rating. Finally, a combination
of boron phosphate and silicone fluid (Comparative Example 5) produced a sample
with an average FOT of 18.8 seconds. This sample also was very close to but did not
meet V-l criteria in that one burn time was longer than 30 seconds.
Comparative Examples 6-11 demonstrate the flame retardance behavior of several
blends that contain electrically conductive carbon black. Comparative Example 6 is
an example of an electrically conductive compatibilized polyamide/poly(arylene
ether) blend without flame retardants. As can be seen, the flame retardancy is very
poor with an average FOT greater than 100 seconds per bar. Comparative Example 7
includes the same boron phosphate/silicone fluid flame retardant system as in
Comparative Example 5. Here the average FOT per bar is now 48.8 seconds where
without the electrically conductive carbon black, it was 18.8 seconds. This shows that
the inclusion of the electrically conductive carbon black actually decreases the overall
flame retardance performance of the blend. Similarly Comparative Example 10 uses
TPP as the flame retardance agent. This blend can be compared to Comparative
Example 4. With the electrically conductive carbon black in the blend, the average
FOT per bar increases from 23.5 seconds to 45.9 seconds.
Examples 1 through 7 show blends that contain a phosphinate. All three samples for
each of these examples show a total average FOT below 5 seconds per bar, even
including from 1.8 to 2.2 parts of electrically conductive carbon black. So, use of a
phosphinate provides V-0 performance in the electrically conductive blends. This is
contrast to the flame retardants used in the comparative examples that all showed non-
V-0 performance with the addition of the electrically conductive carbon black to the
blends.
Additionally, a comparison of the specific volume resistivity of Comparative Example
11 (approximately 24000 Ohm-cm) to the specific volume resistivity of Examples 1
through 7 shows that similar blends that have the same level of carbon black, but
which also include phosphinate exhibit markedly lower resistivity. In all of Examples
1 through 7, the resistivity decreases by at least 97%. So, the inclusion of phosphinate
also unexpectedly reduces the resistivity, or increases the conductivity, of the
compatibilized poly(arylene ether)/polyamide blends.
Examples 8-27
The examples were made using the compositions shown in Table 4 in a 30 millimeter
extruder. The order of addition of the components is also shown in Table 4. The
abbreviation U/S means that the component was added upstream either in the
feedthroat or using a feeder located at the feedthroat. The abbreviation D/S means
that the component was added downstream to a melt mixture formed by the
components added upstream. The flame retardant masterbatch (FR/N6) comprised 40
weight percent OP 1230 and 60 weight percent Nylon 6 #1 based on the combined
weight of OP 1230 and nylon. The abbreviation CCBMB means that the conductive
carbon black was part of a masterbatch. The CCBMB consisted of 10 weight percent
carbon black and 90 weight percent Nylon 6 #1, based on the combined weight of the
carbon black and nylon. The compositions contained 0.3 weight percent (wt%)
potassium iodide, 0.05 wt% copper iodide, 0.3 wt % Irganox 1076 commercially
available from Ciba-Geigy, 0.8 wt% citric acid, all of which were added upstream.
The total weight of all components is 100.25 in each example.
Flammability results are reported as "probability of first time pass" or p(FTP). Twenty
bars of each composition were molded and burned according the UL 94 method and
the average and standard deviation of the flame out times was used to calculate the
probability that in the standard test of five bars the sample would have passed. A 90%
probability of passing the first time (i.e., p(FTP) of 0.9) is considered acceptable
performance. Values significantly lower than 0.9 are considered unacceptable. p(FTP)
is calculated only for samples that do not fail by dripping. Flammability results were
obtained for bars with a thickness of 2.0 millimeters.
Physical property testing was done using the methods listed in Table 3 using the units
also reported in Table 3. Specific volume resistivity (SVR) was determined as
described above and is reported in ohm-centimeters (ohm-cm).
Table 3.
(Table Removed)
In Examples 8-12 the phosphinate was not part of a masterbatch and was added at the
feed throat. Good flame retardance behavior (p(FTP) >0.9 for VO at 2 millimeters)
could only be achieved with 14.0 wt% of phosphinate. The composition showed a
significant loss of impact strength in both the notched and unnotched Izod tests. In
Examples 13-17 the phosphinate was not part of a masterbatch and was added
downstream. Good flame retardance could not be achieved, even with 14.0 wt% of
phosphinate. In contrast, Examples 18-22 show robust flame retardance at lower
loadings of phosphinate and higher notched and unnotched Izod values than Example
12. The phosphinate was added downstream as part of a masterbatch in Examples 18-
22. Examples 23-27 show that a masterbatch added upstream yields results that are
no better than the phosphinate added upstream without being part of a masterbatch.
Examples 28-31
The examples were made using the compositions shown in Table 5 in a 30 millimeter
extruder. The order of addition of the components is also shown in Table 5. The
abbreviation U/S means that the component was added upstream either in the
feedthroat or using a feeder located at the feedthroat. The abbreviation D/S means
that the component was added downstream to a melt mixture formed by the
components added upstream. The MWNT were added as part of a masterbatch
(MWNT MB). The MWNT masterbatch consisted of 20 weight percent multi-wall
nanotubes and 80 weight percent Nylon 6,6, based on the combined weight of the
MWNT and nylon. The compositions contained 0.3 weight percent (wt%) potassium
iodide, 0.05 wt% copper iodide, 0.3 wt % Irganox 1076 commercially available from
Ciba-Geigy, 0.8 wt% citric acid, all of which were added upstream.
Physical property testing was done using the methods listed in Table 3 using the units
also reported in Table 3. Specific volume resistivity (SVR) was determined as
described above and is reported in ohm-centimeters (ohm-cm).
Table 5.
(Table Removed)
Examples 28-31 show the impact of the choice of electrically conductive additive on
the flammability and physical properties of the composition. Examples 28-31 use 1.2
weight percent of MWNT with respect to the total weight of the composition and
achieve comparable conductivity to compositions employing 1.7-2.2 weight percent
conductive carbon black. The reduction in the amount of electrically conductive
additive appears to have a significant effect on the flame retardance behavior of the
composition - excellent flame retardance can be achieved by adding the phosphinate
upstream. Additionally, physical properties such as the impact strength are improved.
Examples 32-44
The examples were made using the compositions shown in Table 6 in a 30 millimeter
extruder. The order of addition of the components is also shown in Table 6. The
abbreviation U/S means that the component was added upstream either in the
feedthroat or using a feeder located at the feedthroat. The abbreviation D/S means
that the component was added downstream to a melt mixture formed by the
components added upstream. The flame retardant masterbatch (FR-MB) comprised
50 weight percent OP 1230 and 50 weight percent Nylon 6,6 based on the combined
weight of OP 1230 and nylon. The talc was added as part of a masterbatch (Talc MB)
that consisted of 45 weight percent talc and 11.6 weight percent Nylon 6 #1, and 43.4
weight percent of Nylon 6/6 #2 based on the combined weight of the talc and nylons.
The compositions contained 0.15 weight percent (wt%) potassium iodide, 0.01 wt%
copper iodide, 0.3 wt % Irganox 1076 commercially available from Ciba-Geigy, 0.7
wt% citric acid, all of which were added upstream. The amounts listed are with
regard to the total weight of the composition.
Flammability results are reported as "probability of first time pass" or p(FTP). Twenty
bars of each composition were molded and burned according the UL 94 method and
the average and standard deviation of the flame out times was used to calculate the
probability that in the standard test of five bars the sample would have passed. A 90%
probability of passing the first time (i.e., p(FTP) of 0.9) is considered acceptable
performance. Values significantly lower than 0.9 are considered unacceptable. p(FTP)
is calculated only for samples that do not fail by dripping. Flammability results were
obtained for bars with a thickness of 1.5 millimeters. p(FTP) is calculated for the
probability of passing VI criteria as discussed above.
Physical property testing was done using the methods listed in Table 7 using the units
also reported in Table 7.
Table 7.
(Table Removed)
Examples 32-44 all contain 17 weight percent talc. In Examples 32-34 the
phosphinate was added by direction addition (not masterbatch). In Example 32 the
phosphinate was added with the PPE, in Example 33 the phosphinate was added
upstream with Nylon 6,6#2, and in Example 34 the phosphinate was added with
Nylon 6,6#2 downstream. Examples 32-34 all show a probability of first time pass
for a UL 94 VI at 1.5 mm of less than 0.9. In Examples 35-36 the phosphinate was
added either entirely in a masterbatch or used a combination of masterbatch addition
and direct addition. Both Examples 35 and 36 showed excellent flame retardance
performance, both having p(FTP) values greater than 0.90.
Example 37 and Example 38 both contain an impact modifier and a greater quantity of
phosphinate than comparable compositions free of impact modifier. Again, Example
37, using a flame retardant masterbatch, demonstrates significantly better flame
retardance than Example 38 in which the composition was prepared using direct
addition of the phosphinate.
Examples 39-41 and Examples 42-44, which contain 20 weight percent talc based on
the total weight of the composition, demonstrate a similar story - direct addition of
the phosphinate does not lead to flame retardance whereas use of a flame retardant
masterbatch does. Additionally, Examples 42-44 demonstrate that upstream addition
of the flame retardant masterbatch can be as effective as downstream addition or a
combination of masterbatch addition and direct feed.
While the invention has been described with reference to exemplary embodiments, it
will be understood by those skilled in the art that various changes may be made and
equivalents may be substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to adapt a particular
situation or material to the teachings of the invention without departing from the
essential scope thereof. Therefore, it is intended that the invention not be limited to
the particular embodiment disclosed as the best mode contemplated for carrying out
this invention, but that the invention will include all embodiments falling within the
scope of the appended claims.

WHAT IS CLAIMED IS:
1. A composition comprising:
a poly(arylene ether);
a polyamide;
an electrically conductive additive;
an impact modifier; and
a phosphinate.
2. A composition comprising:
a poly(arylene ether):
a polyamide:
a reinforcing filler: and
a phosphinate.
3. A method of making a composition comprises:
melt mixing a first mixture comprising a poly(arylene ether) and a compatibilizing agent to form a first melt mixture;
melt mixing a second mixture comprising the first melt mixture and a polyamide, electrically conductive additive and a flame retardant masterbatch wherein the flame retardant masterbatch comprises a phosphinate and a thermoplastic resin.
4. A method of making a composition comprises:
melt mixing a poly(arylene ether), a compatibilizing agent, a polyamide, a reinforcing filler, and a flame retardant masterbatch wherein the flame retardant masterbatch comprises a phosphinate and a thermoplastic resin.

5. The method of Claim 3 or 4 wherein the composition further comprises an
impact modifier.
6. The method of any of Claims 3-5, wherein the flame retardant masterbatch
further comprises an inorganic compound, a nitrogen compound or an inorganic
compound and a nitrogen compound.
7. The composition of Claim 1 or Claim 2 or the method of any of Claims 3-6
wherein the composition has a melt volume rate less than or equal to 25 cubic
centimeters/l0min as determined by Melt Volume Rate test ISO 1133 performed at
300°C with a load of 5 kilograms (kg).
8. The composition or method of any of the preceding claims wherein the
composition has a Vicat B120 greater than or equal to 170°C as determined by ISO
306.
9. The composition or method of any of the preceding claims wherein greater
than or equal to 50 weight percent of the polyamide, based on the total weight of the
polyamide, has a melt temperature within 35% of the glass transition temperature of
the poly(arylene ether).
10. The composition or method of any of the preceding claims wherein the
phosphinate has the formula

(Figure Removed)
wherein R1 and R2 are independently C1-C6 alkyl, phenyl, or aryl; M is calcium, magnesium, aluminum, zinc or a combination comprising one or more of the foregoing; and d is 2 or 3.
11. The composition or method of Claim 10 wherein R1 and R2 are ethyl.
12. A composition produced by the method of any of Claims 3-11.
13. 13. An article comprising a composition of any of the preceding claims.