US 4,539,348 AGranted

Water-swellable crosslinked polymeric microgel particles and aqueous dispersions of organic film-forming resins containing the same

AssigneeCelanese Corporation

InventorsChandrasen Gajria, Yehuda Ozari

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Abstract

Disclosed are carboxylic acid containing polymeric microgel particles which are prepared by polymerizing in aqueous emulsion a monomer mixture containing about 10-50% by weight of polymerizable carboxylic acid monomers, up to 5% of a difunctional crosslinking monomer and one or more carboxyl-free relatively water insoluble polymerizable vinyl monomers. The resulting microgel particles are water-swellable and may be employed as stabilizers for use in the preparation of aqueous dispersions of film-forming resins containing smaller amounts of organic solvents than conventional aqueous dispersions of this type. Such dispersions are useful as coating compositions, yielding coatings having less water sensitivity and improved adhesion as compared with coatings obtained from conventional aqueous dispersions of film-forming resins.

Claims10

Dependent claims

A stable aqueous dispersion of organic, water-dispersible film-forming resin, comprising:

a. at least one water-dispersible, film forming resin dissolved in an organic water-miscible solvent wherein the film-forming resin is selected from the group consisting of heat-curable, thermosetting epoxy resins, phenolic resins, alkyd resins, polyester resins, aminoplast resins and mixtures thereof and wherein the organic solvent has a boiling point of about 150.degree. F. to about 500.degree. F.;
b. a dispersing amount of an aqueous solvent medium;
and
c. from about 10 to 50% by weight, based on the total solids weight of the dispersion, of a stabilizer for stabilizing said film-forming resin in said aqueous solvent medium, said stabilizing comprising crosslinked, aqueous emulsion polymerized microgel particles comprising the addition copolymerization product of:
(i) a major amount of at least one polymerizable carboxylic acid group-free polymerizable vinyl monomer selected from the group consisting of polymerizable vinyl aromatic monomers, methacrylate ester monomers, nitrile monomers, vinyl halide monomers, mixtures thereof, and mixtures thereof with minor amounts of vinyl ester monomers and alkyl acrylate monomers,
(ii) from about 10-50%, based on the total monomer weight, of at least one polymerizable vinyl monomer selected from the group consisting of .alpha., .beta.-ethylenically unsaturated carboxylic acid monomers and mixtures thereof, said carboxylic acid monomers being substantially non-gelling when copolymerized with said acid group-free monomers in an aqueous emulsion, and
(iii) from a small amount sufficient to cross-link the microgel particle up to about 5%, based on the total monomer weight, of a difunctional crosslinking monomer having at least two polymerizable double bonds,
said microgel particles being water-swellable, exhibiting a stability in aqueous media of at least about one week when an aqueous dispersion of said microgel particles of about 20% solids content is maintained at 140.degree. F., and having further the acid groups thereof at least partially neutralized with ammonia or a volatile organic amine in an amount sufficient to provide a pH of about 2 to about 10 to said aqueous dispersion.

5 more elements

A stable aqueous dispersion of thermosetting organic film-forming resin suitable for use as a heat-curable coating composition, comprising:

a. from about 50 to about 90% by weight, based on the total solids weight of the dispersion, of at least one thermosetting film-forming resin selected from the group consisting of epoxy resins comprising a glycidyl polyether of a polyhydric phenol or hydrogenated phenol containing an average of more than one epoxide group per molecule and having an epoxy equivalent weight in the range between about 150 to about 8000, phenolic resole resins, and mixtures thereof, dissolved in a water-miscible organic solvent having a boiling point of about 150.degree. F. to about 500.degree. F., said organic solvent forming less than about 20% by weight of the total dispersion;
b. an aqueous solvent medium in an amount sufficient to disperse said film-forming resin and to provide a total solids content of from about 15 to 40% by weight;
c. from about 10 to about 50% by weight, based on the total solids weight of the dispersion, of water-swellable microgel particles, said microgel particles having a stability in aqueous media of at least about four weeks when an aqueous dispersion of said microgel particles of about 20% solids is maintained at 140.degree. F. and comprising the addition copolymerization product, formed in an aqueous emulsion, of:
(i) from about 10-50%, based on the total monomer weight, of methacrylic acid,
(ii) from a small amount sufficient to cross-link the microgel particle up to about 5%, based on the total monomer weight, of divinylbenzene,
(iii) from about 10 to about 90%, based on the total monomer weight, of styrene,
(iv) from about 0 to about 50%, based on the total monomer weight, of methyl methacrylate, and
(v) from about 0 to about 10%, based on the total monomer weight, of ethyl acrylate, vinyl acetate and mixtures thereof, said microgel particles having the acid groups thereof at least partially neutralized with ammonia or a volatile organic amine in an amount sufficient to provide a pH of about 2 to about 10 to said aqueous dispersion;
and
d. from about 0 to about 10% by weight, based on the total solids weight of the dispersion, of an aminoplast resin.

7 more elements

Dependencies are inferred from the claim text.