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...
Patent
1998-02-25
1999-10-19
Marquis, Melvyn I.
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...
526279, 523201, C08L 4304
Patent
active
059690372
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a room temperature curing composition for various coating systems, particularly for weather-resistant, durable coatings, to be applied to outer surfaces of architectural structures, automobiles, household electric appliances, plastic products and so on.
BACKGROUND OF THE INVENTION
Recently, in the field of coatings and adhesives, organic solvent-based systems are being replaced with water-soluble or dispersible systems as an anti-pollution measure or resource saving.
However, the conventional water-based coatings have disadvantages in that, since they have no crosslinkable functional group in the molecules, they are subject to the strong influence of surfactants used in the polymerization, which remarkably deteriorate the weatherability, water resistance and stain resistance of formed coating films, resulting in inferior film performances as compared with solvent-based paints.
Therefore, to provide crosslinkable functional groups in the molecules, an application of an alkoxysilyl group-containing emulsion to the field of coatings has been proposed. However, the alkoxysilyl group is easily hydrolyzed in the presence of water so that the film-forming performance of the emulsion is deteriorated considerably after aging and, moreover, the emulsion is poor in mechanical stability and white enamel gloss.
SUMMARY OF THE INVENTION
As a result of making intensive studies in order to solve above problems, inventors of the present invention have found that when multi-stage emulsion polymerization is performed, and polymerizable monomers containing an alkoxysilyl group which is relatively stable against hydrolysis (e.g. triethoxysilyl group, diethoxysilyl group, tripropoxysilyl group, dipropoxysilyl group) are introduced to emulsion particles as a reactive silyl group, the stability of the silyl groups is remarkably enhanced so that the silyl groups are prevented from hydrolysis in the course of polymerization or during storage. Additionally when hydrophilic groups are introduced into the outermost shell layer of the emulsion particles, the mechanical stability and white enamel gloss are both remarkably improved. This invention has been developed on the basis of the above findings.
This invention is, therefore, directed to a room temperature curing composition comprising an emulsion obtained by a multi-stage emulsion polymerization of the plurality of constituent monomers, wherein the core monomer composition of emulsion particles comprises 1 to 30 weight % of (A) a silyl group-containing vinyl monomer of the general formula (I) and 70 to 99 weight % of (B) at least one vinyl monomer copolymerizable with the above-mentioned component (A), and the outer shell monomer composition of the emulsion particles comprises 0.1 to 30 weight % of (A) a silyl group-containing vinyl monomer of the general formula (I), 40 to 99.4 weight % of (B) at least one vinyl monomer copolymerizable with the above-mentioned component (A) and 0.5 to 30 weight % of (D) at least one hydrophilic vinyl monomer selected from the group consisting of .alpha.,.beta.-ethylenically unsaturated carboxylic acid, styrenesulfonic acid, vinylsulfonic acid, sodium styrenesulfonate, 2-sulfoethyl methacrylate sodium, 2-sulfoethyl methacrylate ammonium, (meth)acrylamide, N-methylol(meth)acrylamide, dialkylaminoalkyl methacrylates, dialkylaminoalkyl methacrylate hydrochlorides, 2-aminoethyl methacrylate hydrochloride, polyethoxylated vinyl monomers and polypropoxylated vinyl monomers; ##STR1## wherein R is a monovalent hydrocarbon group, selected from alkyl group having 1 to 10 carbon atoms, aryl group and aralkyl group, X is a group selected from ethoxy, n-propoxy and i-propoxy groups, y is an integer of 0 to 2; in the case where two or more R or X groups are bound to Si respectively, they may be the same or different.
The vinyl monomer (B) of the above-mentioned outermost shell preferably comprises of 10 to 75 weight % of component (C) based on the total monomer amount of the outermost shell. The component (
REFERENCES:
patent: 5332766 (1994-07-01), Takaya et al.
patent: 5668194 (1997-09-01), Ando et al.
patent: 5708093 (1998-01-01), Bastelberger et al.
patent: 5852095 (1998-12-01), Yamauchi et al.
Bourne T. R. et al.: "Feasibility of Using Alkoxysilane-functional Monomers for the Development of Crosslinkable Emulsions" Journal of Coatings Technology, vol. 54, No. 684, Jan. 1982, pp. 69-82, XP000196796 * p. 1, col. 1, line 1--col. 2, line 10.
Ando Naotami
Hatano Takanori
Kanegafuchi Chemical Industry Co. Ltd.
Marquis Melvyn I.
Milstead Mark W.
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