Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-01-19
2002-10-22
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S501000, C524S516000, C524S517000, C524S811000
Reexamination Certificate
active
06469097
ABSTRACT:
The present invention relates to aqueous dispersions of polymers obtained from the emulsion polymerization of a mixture of monomers, in which at least one of the monomers is. an unsaturated heterocycle. The invention also relates to the use of these aqueous polymer dispersions in crosslinking processes.
Coating compositions which crosslink at a temperature of above or equal to room temperature are known from the prior art. Some of these compositions result from reactions between latices separately comprising carboxylic ester functions and hydroxyl functions, or between latices comprising both hydroxyl functions and.carboxylic ester functions, particularly in the form of &bgr;-hydroxy ester.
The reactions between the hydroxyl and carboxylic ester functions can be initiated and catalysed at room temperature with catalytic systems created in situ, after reacting a nucleophile such as, for example, an imidazole with an epoxide.
However, these compositions have a certain number of drawbacks.
The main problem is the stability on storage, also known as the “pot life”, of mixtures containing the abovementioned latices and the catalytic system.
Specifically, the mixtures of latex and of catalytic system of the prior art have a pot life which is much too short to make them manipulable and economically interesting: the pot life is often less than or equal to 4 hours.
In addition, the use of the catalytic systems of the prior art can pose formulation problems: the nucleophilic compound is not always easy to disperse in the reaction medium, and more particularly in aqueous medium.
Moreover, although room-temperature crosslinking processes have already been described, the crosslinking is generally efficient only at temperatures above room temperature.
It has been observed, entirely surprisingly and unexpectedly, that by modifying certain parameters of the catalytic system, in particular the starting nucleophile, it is possible to overcome the drawbacks mentioned above.
Thus, the aim of the present invention is to propose a polymer based on an unsaturated nucleophilic heterocycle which, when mixed a latex, has an improved stability on storage (pot life) and good reactivity at the time of use.
Another aim of the invention is to propose a polymer based on an unsaturated nucleophilic heterocycle which does not pose any problems of dispersion in a given reaction medium.
Finally, another aim of the invention is to propose a polymer based on an unsaturated nucelophilic heterocycle which efficiently initiates and catalyses room-temperature crosslinking processes.
To this end, a subject of the invention is an aqueous dispersion of a water-insoluble polymer (I) obtained from the emulsion polymerization of a mixture of monomers comprising:
at least one unsaturated heterocyclic monomer (A),
and optionally at least one ethylenically unsaturated monomer (B).
A subject of the invention is also a process for crosslinking a latex (II) containing an epoxide function, using the dispersion of polymer (I).
The invention thus relates firstly to an aqueous dispersion of a water-insoluble polymer (I) obtained from the emulsion polymerization in water of a mixture of monomers comprising:
at least one unsaturated heterocyclic monomer (A):
comprising at least one nucleophilic hetero atom,
containing at least one exocyclic ethylenic unsaturation, and
whose heterocycle comprises at least one ethylenic unsaturation, and
optionally at least one ethylenically unsaturated monomer (B) containing a function chosen from (meth)acrylamides, carboxylic acids or carboxylic acid salts, carboxylic esters, organosulphuric acids or organosulphuric acid salts, sulphonic acids or sulphonic acid salts, phosphonic acids or phosphonic acid salts, vinyl esters and aromatic monomers containing at least one exocyclic ethylenic unsaturation.
In the context of the present invention, the term “polymerization” means either homopolymerization (polymerization of identical monomers) or copolymerization (polymerization of different monomers).
According to an essential characteristic of the invention, the polymer (I) is in the form of an aqueous dispersion. Such aqueous polymer disperions are commonly known as latices.
The polymer (I) is obtained from the emulsion polymerization of at least one monomer. (A) This monomer (A) comprises at least one nucleophilic hetero atom. The expression “nucleophilic hetero atom” means a trivalent hetero atom belonging to group VB of the Periodic Table of the Elements. Throughout the specification, the Periodic Table is that of the “supplement to the Bulletin of the French Chemical Society, No. 1, January 1966”. These hetero atoms may be nitrogen, phosphorus, arsenic, antimony or bismuth. The nucleophilic hetero atom is preferably nitrogen. The unsaturated heterocyclic monomers (A) preferably comprise at least nucleophilic hetero atoms, in particular two nitrogen atoms.
The monomer A should also contain an ethylenic unsaturation in its heterocycle and an exocyclic ethylenic unsaturation. At least one of the nucleophilic hetero atoms and/or at least one of the carbon atoms of the heterocycle may be substituted with a carbon-based chain containing at least two carbon atoms and at least one ethylenic unsaturation, it being possible for the carbon-based chain to be optionally functionalized. Substituents which may be mentioned as a guide are carbon-based chains, in particular vinyl, allyl, propenyl, butenyl and butadienyl, and functionalized carbon-based chains, in particular acrylate and methacrylate. In the monomer A, at least one of the carbon atoms of the unsaturated heterocycle can also be substituted with at least one linear or branched alkyl group containing 1 to 8 carbon atoms. In this respect, the linear or branched alkyl group can be methyl, ethyl, propyl, isopropyl or n-butyl.
The monomers (A) can belong to the imidazole, imidazoline, amidine or guanidine family. They preferably belong to the imidazole family. The monomer is more particularly N-vinylimidazole.
In the present invention, the polymer (I) can be a homopolymer obtained from the homopolymerization of a mixture composed exclusively of monomers (A), the monomers (A) being identical. The polymer (I) can also be a copolymer obtained from the copolymerization of a mixture of monomers (A) and (B).
The monomer B is ethylenically unsaturated and contains a function chosen from carboxylic acid or carboxylic acid salts, carboxylic esters, organosulphuric acids or organosulphuric acid salts, sulphonic acids or sulphonic acid salts, phosphonic acids or phosphonic acid salts, vinyl esters, (meth)acrylamides or aromatic monomers (B) containing at least one exocyclic ethylenic insaturation.
The ethylenically unsaturated monomer (B) may be chosen more particularly from:
carboxylic acids or carboxylic acid salts of the (meth)acrylic type, such as acrylic acid, methacrylic acid or sodium acrylate; dicarboxylic acids such as itaconic acid, maleic acid or fumaric acid; hemiesters thereof, such as the methyl, ethyl, propyl, n-butyl or isobutyl hemiesters; or salts thereof such as the sodium, potassium or ammonium salts thereof,
carboxylic esters of the acrylic type in which the alkyl group contains from 1 to 20 carbon atoms, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, decyl acrylate, decyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate or stearyl methacrylate,
organosulphuric acids or the alkali metal or alkaline-earth metal salts of organosulphuric acids, such as vinylsulphuric acid or vinylphenylsulphuric acid,
sulphonic acids or the alkali metal or alkaline-earth metal salts of sulphonic acids, for example vinylsulphonic acids such as vinylsulphonic acid, styrenesulphonic acid, 2-acrylamido-2-methylpropanesulphonic acid or sodium methallyl sulphonate,
phosphonic acids or the alkali metal or alkaline-earth metal salts of
Bett William
Charmot Dominique
Granier Vincent
Rhodia Chimie
Yoon Tae H.
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