The present invention concerns new associative thickening agents belonging to the category
of HEURs (Hydrophobically modified Ethylene oxide URethane). These products contain an
original associative monomer with a base of alkyl cyclohexanol alkoxylates. Their thickening
power is equal to or greater than that procured by HEUR associative thickening agents of the
prior art containing grafted alkyls phenols. An efficient substitute product is therefore
available, which is free of alkyls phenols, matching current market demand.
Water-based paint formulations containing mineral fillers consist of an aqueous phase, one or
more polymers in emulsion in the liquid phase called binders, fillers and/or pigments, a
dispersing agent and admixtures as diverse as surfactants, coalescence agents, biocides, antifoaming
agents and, finally, at least one thickening agent.
The latter enables the rheology of the water-soluble formulations into which it is introduced,
and notably water-soluble paints, to be controlled, both at the manufacturing stage, and
during transport or storage, or at the time of application. The wide variety of practical
constraints in each of these stages relates to a multiplicity of different rheological properties.
Nevertheless, it is possible to summarise the requirement of the skilled man in the art in
obtaining an effect of the thickening of the water-based formulation, both for reasons of
stability over time, and for a possible application of the paint to a vertical surface, lack of
spattering during use, etc. For this reason, additives have been designated which contribute
to this regulation of the rheological properties under the term “thickening agents”.
Among these products, thickening agents known as "associative" thickening agents are
distinguished, which are hydrosoluble polymers having insoluble hydrophobic groups. Such
macromolecules have an associating character: when introduced into water, the hydrophobic
groups tend to assemble in the form of micellar aggregates. These aggregates are linked
together by the hydrophilic parts of the polymers: a three-dimensional network is then formed
which causes the viscosity of the medium to be increased.
The functional mechanism and the characteristics of the associative thickening agents are
now well known and described, for example in the documents “Rheology modifiers for
water-borne paints” (Surface Coatings Australia, 1985, pp. 6-10) and "Rheological modifiers
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for water-based paints: the most flexible tools for your formulations” (Eurocoat 97, UATCM,
vol. 1, pp 423-442).
Among these associative thickening agents, the class of associative thickening agents of the
HEUR type (Hydrophobically modified Ethylene oxide URethane) is distinguished. They
designate copolymers resulting from the synthesis between a compound of the polyalkylene
glycol type, a polyisocyanate, and a monomer or condensate designated "associative", of the
alkyl, aryl or aryalkyl type consisting of a hydrophobic terminal group.
These structures are well known to develop high viscosities, with a medium to low shearing
gradient (J. of Applied Polymer Science, vol. 58, p 209-230, 1995; Polymeric Mat. Sci. and
Engineering, vol. 59, p 1033, 1988; Polymeric Mat. Sci. and Engineering, vol. 61, p 533,
1989; Polymeric Paint Colour Journal, vol. 176, n° 4169, p 459, June 1986), which is equal
respectively to the Stormer™ (KU) and Brookfield™ (mPa.s) viscosity measurements.
At the same time, document EP 1 566 393 describes a thickening agent of the HEUR type
one of the essential characteristics of which is the presence of n-butyl-1-octanol, while its
hydrophobic groups are based on fatty alcohols having 8 to 18 carbon atoms.
Document EP 1 013 264 describes a polyurethane thickening agent for cosmetic
formulations, having an associative monomer functionalised by a hydrophobic group which
may be linear or branched, but is preferentially linear, and having 12 to 24 carbon atoms.
Document WO 94/06840 proposes an associative thickening agent of the HEUR type,
characterised by a certain density of hydrophobic groups, where the said groups are linear
alkyl chains having 8 to 22 carbon atoms.
Document EP 1 584 331 proposes a hydrophobic terminal group having 6 to 34 carbon atoms
for the associative monomer. To increase specifically the Brookfield™ viscosity.
Document EP 0 639 595 proposes linear hydrophobic groups having 4 to 36 carbon atoms.
4
Document WO 02/102868 also makes reference to linear structures for the associative
monomer.
Independently of the particular rheological profiles provided by the variations described
above, the HEURs with the most pronounced thickening power still remain molecules having
alkyl phenols grafted on to their associative monomer. One of the representative products of
this technology is Acrysol™ SCT-275, developed by the company DOW™. And alkyl
phenols are currently widely suspected of being carcinogenic, and dangerous for
reproduction; although still tolerated in the paints industry they nonetheless remain in the
firing line of the legislative institutions, notably the European ones.
There is therefore a genuine requirement to develop a HEUR-type associative thickening
agent, which is free of alkyls phenols, but which has an equivalent or even improved
thickening power.
Continuing its research along these lines, the Applicant observed in a completely surprising
manner that the use of certain structures in place of the associative monomer led to such a
result. This technological advance is based on the use, as an associative monomer, of a
compound the structure of which satisfies the following formula (I):
(I)
where:
- m and n are integers of less than 150, at least one of which is non-zero,
- A and B designate alkyl groups which are different one from another, and having 2 to 4
carbon atoms, where group AO preferentially designates ethylene oxide, and group BO
preferentially designates propylene oxide,
- R designates an alkyl group, whether linear or branched, containing 8 to 20 carbon atoms,
and preferentially a linear alkyl group having 9 to 12 carbon atoms.
Such compounds have been identified as surfactants, and are obtained by alkoxylation of an
alkyl phenol and hydrogenation of the product obtained. Reference may notably be made to
5
the document US 6 111 146 which describes their synthesis. The resulting compounds are
designated by the expression "alkyl cyclohexanol alkoxylates". It is important to add that the
final structure is not that of an alkyl phenol, and that the resulting product will not be
categorised as such.
The associative thickening agents which result from the polymerisation of this monomer of
formula (I), of at least one polylakylene glycol and at least one polyisocyanate, have no
alkyls phenols; in an unexpected and particularly advantageous manner, they enable a waterbased
paint to be thickened to a level of viscosity at least equal to that provided by HEURs of
the prior art containing alkyl phenols. It is even demonstrated that it is possible to obtain for
the invention a rheological profile similar to that proposed by the products of the state of the
art for alkyl phenols. A product has therefore successfully been developed which is at least
equivalent, and which overcomes the problem relating to the use of alkyl phenols.
Thus, a first object of the invention consists of hydrosoluble polyurethanes resulting from the
condensation:
a) of at least one polyalkylene glycol, and
b) of at least one polyisocyanate, and
c) of at least one monomer of formula (I) :
(I)
where:
- m and n are integers of less than 150, at least one of which is non-zero,
- A and B designate alkyl groups which are different one from another, and having 2 to 4
carbon atoms, where group AO preferentially designates ethylene oxide, and group BO
preferentially designates propylene oxide,
- R designates an alkyl group, whether linear or branched, containing 8 to 20 carbon atoms,
and preferentially a linear alkyl group having 9 to 12 carbon atoms.
6
"Polyalkylene glycol" is understood to mean a polymer of an alkylene glycol derived from an
olefinic oxide. The polyalkylene glycol according to the present invention is, for example,
polyethylene glycol, polypropylene glycol, polybutylene glycol or a polyalkylene glycol
containing a proportion of an ethylene-oxy group and/or a proportion of a propylene-oxy
group and/or a proportion of a butylene-oxy group. The polyalkylene glycol according to the
present invention can, for example, include a dominant proportion of an ethylene-oxy group
in association with a secondary proportion of a propylene-oxy group. Specific examples of
alkylene glycol polymers include: polyalkylene glycols having an average molecular weight
of 1,000, 4,000, 6,000, 10,000 and 20,000 g/mol (in the case of polyethylene glycol called
PEG-1000, PEG-4000, PEG-6000, PEG 10000 and PEG 20000); polyethylene polypropylene
glycols having a percentage of ethylene oxide of between 20 and 80% by weight and a
percentage of propylene oxide of between 20 and 80% by weight.
"Polyisocyanate" is understood to mean a compound which includes at least
2 functional isocyanate groups –N=C=O.
The Applicant stipulates that the manufacture of these polyurethanes, which belong to the
family of HEUR-type thickening agents, is known to the skilled man in the art, who can refer
to the teaching of the documents cited above as the technological background of the present
invention.
According to one embodiment of the present invention, these polyurethanes result from the
condensation of, expressed as a % by weight of each of the monomers, where the sum of
these %s is equal to 100%:
a) 90% to 99.5% of at least one polyalkylene glycol,
b) 0.5% to 10% of at least one polyisocyanate and
c) 90% to 99.5% of at least one monomer of formula (I).
According to one embodiment of the present invention, the polylakylene glycol constituting
the polyurethane is polyethylene glycol,
7
According to another embodiment of the present invention, this is a polyethylene glycol of
molecular mass of between 2,000 g/mole and 20,000 g/mole, for example between 8,000
g/mole and 15,000 g/mole, or for example between 8,000 g/mole and
12,000 g/mole.
According to one embodiment, the polyisocyanate constituting the polyurethane according to
the invention is chosen from among toluene diisocyanate and its dimers and trimers, 1,4-
butane diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, 1,3- and 1,4-
cyclohexane diisocyanate, 4,4’diisocyanatodicyclohexylmethane, 1-methyl-2,4-
diisocyanatocyclohexane and its blend with 1-methyl-2,6-diisocyanatocyclohexane, the biuret
of hexamethylene diisocyanate and its dimers and trimers and their blends.
A second object of the present invention consists of aqueous compositions containing water,
at least one polyurethane according to the invention, together with at least one surfactant, and
possibly at least one additive chosen from among a biocide, a solvent, an anti-foaming agent,
a pH regulator, a coalescence agent, or their blends.
A "biocide" is understood to mean a chemical substance intended to destroy, repel or make
harmless harmful organisms, to prevent their action, or to oppose them in any other manner,
through a chemical or biological action.
A "non-ionic surfactant" or "non-ionic surfactant agent" is understood to mean a non-ionic
molecule consisting of at least a hydrophilic part and of at least a hydrophobic part.
An "anti-foaming agent" is understood to mean a substance or a formulation intended to
destroy air bubbles within a homogenous or heterogeneous liquid medium (or at its surface),
or to prevent their formation.
A "pH regulator" or "pH regulating agent" is understood to mean a chemical compound
which enables the pH to be adjusted to the expected value. For example, the pH regulating
agent can increase the pH; this is the case with bases, such as NaOH. Alternatively, the pH
regulating agent can reduce the pH ; this is the case with acids.
8
A "coalescent agent" is understood to mean an agent used in paints which enables the
Minimum Film Formation Temperature (MFFT) of paint to be reduced to a temperature
suitable for the desired condition(s) of application (for example a TMFF of 5°C for outside
application). As an example of a coalescent agent according to the invention, propylene
glycol, butyl glycol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate or 2,2,4-trimethyl-1,3-
pentanediol diisobutyrate may be cited.
According to one embodiment, the aqueous compositions of the invention contain, expressed
as a % by weight of each of their constituents, where the sum of these %s is equal to 100%:
1) 5% to 45% of at least one polyurethane according to the invention,
2) 5% to 30% of at least one surfactant,
3) 25% to 75% of water,
4) 0 to 5% of at least one additive chosen from among a biocide, a solvent, an anti-foaming
agent, a pH regulator, a coalescence agent and their blends.
Another object of the present invention consists in the use of the said polyurethanes and of
the said compositions, as thickening agents in aqueous formulations, where the said
formulations are for example chosen from among water-based paints, lacquers, varnishes,
paper coating colors, cosmetic formulations and detergent formulations.
Another object of the present invention lies in the aqueous formulations containing the
thickening agents or polyurethanes and the compositions according to the invention, where
the said formulations are for example chosen from among water-based paints, lacquers,
varnishes, paper coating colors, cosmetic formulations and detergent formulations.
A final object of the present invention consists of a method for preparing a polyurethane
according to the invention, consisting of a condensation of its different constituents.
The following examples enable the invention to be better understood, without however
limiting its scope.
9
EXAMPLES
Example 1
This example illustrates the manufacture of a water-based paint, in which a thickening agent
of the prior art containing an alkyl phenol having 15 carbon atoms and a thickening agent
according to the invention, the R group of which is a linear alkyl chain having 9 carbon
atoms, are used: the corresponding hydrophobic group therefore contains 15 carbon atoms in
this case.
Test n° 1:
This test illustrates the prior art. This corresponds to the use of an aqueous composition with
17.5% by dry weight of a polymer containing grafted alkyl phenols, which is Acrysol™ SCT-
275 sold by the company Dow™.
Test n° 2:
This test illustrates the prior art. This corresponds to the use of an aqueous composition
containing 17.5% by dry weight of a polymer consisting of, expressed as a % by weight of
each of its monomers:
a) 75% of polyethylene glycol of molecular mass by weight equal to
10,000 g/mole,
b) 5% of isophorone diisocyanate,
c) 15% by weight of a monomer of formula HO – (OE)n – R
where OE is ethylene oxide, n is equal to 25 and R is the alkyl phenol group having
15 carbon atoms.
Test n° 3:
This test illustrates the invention. This corresponds to the use of an aqueous composition
containing 17.5% by dry weight of a polymer consisting of, expressed as a % by weight of
each of its monomers:
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a) 75% of polyethylene glycol of molecular mass by weight equal to
10,000 g/mole,
b) 5% of isophorone diisocyanate,
c) 15% by weight of a monomer of the following formula:
(I)
where m = 0 and n = 25 and R designates the linear alkyl group having 9 carbon atoms.
In each of the tests n° 1 to 3, 70.6 grams of Mowilith™ LDM 1871, 193.8 grams of
bipermuted water and 32 grams of the composition to be tested are introduced into the
beaker.
The pH is adjusted by using ammonia (28%) to a value of between 8.6 and 8.9.
At 25°C, the Brookfield™ viscosity at 10 and 100 revolutions per minute (μBk10 and μBk100)
and the Stormer™ viscosity (μS) of the paint are measured.
The results are shown in table 1.
Test n° 1 2 3
Prior Art
INvention
PA PA IN
μBk10 13,600 12,200 13,800
μBk100 8,700 6,800 8,850
μS 135 122 139
Table 1
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WE CLAIM:
1 - Hydrosoluble polyurethanes resulting from the condensation:
a) of at least one polyalkylene glycol,
b) of at least one polyisocyanate, and
c) of at least one monomer of formula (I):
(I)
where:
- m and n are integers of less than 150, at least one of which is non-zero,
- A and B designate alkyl groups which are different one from another, and having
2 to 4 carbon atoms,
- R designates an alkyl group, whether linear or branched, containing 8 to
20 carbon atoms.
2 - Polyurethanes according to claim 1, according to which the AO group designates
ethylene oxide, and the BO group designates propylene oxide.
3 - Polyurethanes according to any one of the previous claims, according to which R
designates a linear alkyl group having 9 to 12 carbon atoms.
4 - Polyurethanes according to any of the previous claims, according to which the
polyalkylene glycol is polyethylene glycol.
5 - Polyurethanes according to any of the previous claims, characterised in that the
polyalkylene glycol is a polyethylene glycol of molecular mass by weight of between
2,000 g/mol and 20,000 g/mol.
12
6 - Polyurethanes according to any of the previous claims, characterised in that the
polyalkylene glycol is a polyethylene glycol of molecular mass by weight of between
8,000 g/mol and 15,000 g/mol.
7 - Polyurethanes according to any one of the previous claims, characterised in that the
polyisocyanate is chosen from among toluene diisocyanate and its dimers and trimers,
1,4-butane diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, 1,3- and
1,4- cyclohexane diisocyanate, 4,4’diisocyanatodicyclohexylmethane, 1-methyl-2,4-
diisocyanatocyclohexane and its blend with 1-methyl-2,6-diisocyanatocyclohexane,
the biuret of hexamethylene diisocyanate and its dimers and trimers and their blends.
8 - Aqueous compositions containing water, at least one polyurethane according to any
one of claims 1 to 7, and at least one surfactant.
9 - An aqueous composition according to claim 8, also containing an additive chosen
from among a biocide, a solvent, an anti-foaming agent, a pH regulator, a coalescence
agent or their blends.
10 - Compositions according to claim 8 or 9, characterised in that they contain, expressed
as a % by weight of each of its constituents, where the sum of these %s is equal to
100%:
1) 5% to 45% of at least one polyurethane according to any one of claims 1 to 7,
2) 5% to 30% of at least one surfactant,
3) 25% to 75% of water,
4) 0 to 5% of at least one additive chosen from among a biocide, a solvent, an antifoaming
agent, a pH regulator, a coalescence agent or their blends.
11 - Use of the polyurethanes according to one of the claims 1 to 7, or a composition
according to one of the claims 8 to 10, as thickening agents in aqueous formulations.
13
12 - Use according to claim 11, according to which the said aqueous formulations are
chosen from among water-based paints, lacquers, varnishes, paper coating colors,
cosmetic formulations or detergent formulations.
13 - Aqueous formulations containing the polyurethanes or the compositions according to
any one of the claims 1 to 10, where the said formulations are chosen from among
water-based paints, lacquers, varnishes, paper coating colors, cosmetic formulations
and detergent formulations.
14 - A method for preparing a polyurethane according to any one of claims 1 to 7,
consisting of a condensation of its different constituents.