Preparation of a multicoat coating, water-thinnable coating compositions, water-thinnable emulsion polymers and preparation of water-thinnable emulsion polymers

Water-thinnable coating compositions which comprise a water-thinnable emulsion polymer which is obtained by a process comprising the steps

• (a) polymerizing in a first stage 10 to 90 parts by weight of a mixture of ethylenically unsaturated monomers in aqueous phase in the presence of one or more emulsifiers and one or more radical-forming initiators, the mixture of ethylenically unsaturated monomers being chosen such that the first stage gives rise to a polymer having a glass transition temperature (T.sub.G1) of +30.degree. to +110.degree. C., wherein the monomers used in the first stage comprise
• (a1) 99.5 to 60% by weight of a cycloaliphatic or aliphatic ester of methacrylic acid or acrylic acid or a mixture of such esters, and
• (a2) 0.5 to 40% by weight of a monomer which copolymerizable with (a1) or a mixture of such monomers,
• the total of the weight percentages of (a1) and (a2) being always 100% b weight, and (a1) and (a2) being free of hydroxy and carboxyl functionality, and
• (b) polymerizing in a second stage 90 to 10 parts by weight of a mixture of ethylenically unsaturated monomers, after at least 80% by weight of the ethylenically unsaturated monomer or the mixture of monomers used in the first stage has reacted in the presence of the polymer obtained in the first stage, the mixture of ethylenically unsaturated monomers used in the first stage and the nature and amount of the mixture of monomers used in the second stage being chosen such that an exclusive polymerization of the mixture of ethylenically unsaturated monomers used in the second stage gives rise to a polymer having a glass transition temperature (T.sub.G2) of -60.degree. to +20.degree. C.,
• wherein a mixture is used in the second stage which comprises
• (b1) 47 to 99% by weight of a cycloaliphtic or aliphatic ester of methacrylic acid or acrylic acid or a mixture of such esters,
• (b2) 1 to 20% by eight of a monomer which carries at least one hydroxyl group and is copoloymerizable with (b1), (b3), and (b4), or a mixture of such monomers,
• (b3) up to 8% by weight of a monomer which carries at least one carboxyl or sulfonic acid group and copolymerizable with (b1), (b2), and (b4), or a mixture of such monomers, and
• (4) 0 to 25% by weight of a further monomer which is copolymerizable with (b1), (b2), and (b3), or a mixture of such monomers,
• the total of the weight percentages of (b1), (b2), (b3), and (b4) being always 100% by weight, the reaction conditions being chosen such that the resultant emulsion polymer has a number average molecular mass of 200,000 to 2,000,000, and the nature and amount of the mixture of monomers used in the second stage are chosen such that the resultant emulsion polymer has a hydroxyl value of 2 to 100 and the difference T.sub.G1 -T.sub.G2 is 10.degree. to 170.degree. C.

Water-thinnable emulsion polymers which are obtained by the following steps:

• (a) polymerizing in a first stage 10 to 90 parts by weight of a mixture of ethylenically unsaturated monomers in aqueous phase in the presence of one or more emulsifiers and one or more radical-forming initiators, the mixture of ethylenically unsaturated monomers being chosen such that the first stage give rise to a polymer having a glass transition temperature (G.sub.T1) of +30.degree. to +110.degree. C.
• where in the monomers used in the first stage comprise
• (a1) 99.5 to 60% by weight of a cycloaliphatic or aliphatic ester of methacrylic acid or acrylic acid or a mixture of such esters, and
• (a2) 0.5 to 40by weight of a monomer which is copolymerizable with (a1) or a mixture of such monomers,
• the total of the weight percentage of (a1) and (a.sub.2) being always 100% by weight, and (a1) and (a2) being free of hydroxy and carboxyl functionality, and
• (b) polymerizing in a second stage 90 to 10 parts by weight of a mixture of ethylenically unsaturated monomers, after at least 80% by weight of the ethylenically unsaturated monomer or the mixture of monomers used in the first stage has reacted, in the presence of the polymer obtained in the first stage, the mixture of ethylenically unsaturated monomers used in the second stage being chosen such that an exclusive polymerization of the mixture of ethylenically unsaturated monomers used in the second stage gives rise to a polymer having a glass transition temperature (T.sub.G2) of -60.degree. to +20.degree. C.,
• wherein a mixture is used in the second stage which comprises
• (b1) 47 to 99% by weight of a cycloaliphatic or aliphatic ester of methacrylic acid or acrylic acid or a mixture of such esters,
• (b2) 1 to 20% by weight of a monomer which carries at least one hydroxyl group and is copolymerizable with (b1), (b3), and (b4), or a mixture of such monomers,
• (b3) up to 80 by weight of a monomer which carries at least one carboxyl or sulfonic acid group and is copolymerizable with (b1), (b2), and (b4), or a mixture of such monomers, and
• (b4) 0 to 25% by weight of a further monomer which is copolymerizable with (b1), (b2), and (b3), or a mixture of such monomers, the total of the weight percentages of (b1), (b2), (b3), and (b4) being always 100% by weight, the reaction conditions being chosen such that the resultant emulsion polymer has a number average molecular mass of 200,000 to 2,000,000, and the nature and amount of the mixture of monomers used in the first stage and the nature and amount of the mixture of the monomers used in the first stage and the amount of the mixture of the monomers used in the second stage are chosen such that the resultant emulsion polymer has a hydroxyl value of 2 to 100 and the difference T.sub.G1 -T.sub.G2 is 10.degree. to 170.degree. C.

A process for the preparation of water-thinnable emulsion polymers which comprises the following steps:

• (a) polymerizing in a first stage 10 to 90 parts by weight of a mixture of ethylenically unsaturated monomers in aqueous phase in the presence of one or more emulsifiers and one or more radical-forming initiators, the mixture of ethylenically unsaturated monomers being chosen such that the first stage gives rise to a polymer having a glass transition temperature (T.sub.G1) of +30.degree. to +110.degree. C.,
• wherein the monomers used in the first stage comprise
• (a1) 99.5 to 60% by weight of a cycloaliphatic or aliphatic ester of methacrylic acid or acrylic acid or a mixture of such esters, and
• (a2) 0.5 to 40% by weight of a monomer which copolymerizable with (a1) or mixture of such
• the total of the weight percentages of (a1) and (a2) being always 100 by weight and (a1) and (a2) being free of hydroxy and carboxy functionality, and
• (b) polymerizing in a second stage 90 to 10 parts by weight of a mixture of ethylenically unsaturated monomers, after at least 80% by weight of the ethylenically unsaturated monomer or the mixture of monomers used in the first stage has reacted, in the presence of the polymer obtained in the first stage, the mixture of ethylenically unsaturated monomers used in the second stage being chosen such that an exclusive polymerization of the mixture of ethylenically unsaturated monomers used in the second stage gives rise to a polymer having a glass transition temperature (T.sub.G2) -60.degree. to +20.degree. C.,
• wherein a mixture is used in the second stage which comprises
• (b1) 47 to 99% by weight of a cycloaliphatic or aliphatic ester of methacrylic aid or acrylic acid or a mixture of such esters,
• (b2) 1 to 20% by weight of a monomer which carries at least one hydroxyl group and is copolymerizable with (b1), (3), and (4), or a mixture of such monomers,
• (b3) up to 8% by weight of a monomer which carries at least one carboxyl or sulfonic acid group and is copolymerizable with (b1), (b2), and (b4), or a mixture of such monomers, and
• (b4) 0 to 25% weight of a further monomer which copolymerizable with (b1), (b2), and (b3), or a mixture of such monomer,
• the total of the weight percentages of (b1), (b2), (b3), and (b4) being always 100% by weight, the reaction conditions being chosen such that the resultant emulsion polymer has a number average molecular mass of 200,000 to 2,000,000, and the nature and amount of the mixture of monomers used in the first stage and the nature and amount of the mixture of monomers used in the second stage are chosen such that the resultant emulsion polymer has a hydroxyl value of 2 to 100 and the difference T.sub.G1 -T.sub.G2 is 10.degree. to 170.degree. C.

A process for the preparation of a water thinnable emulsion polymer consisting of the steps of

• (a) polymerizing in a first stage 10 to 90 parts by weight of an ethylenically unsaturated monomer or a mixture of ethylenically unsaturated monomers in aqueous phase in the presence of one or more emulsifiers and one or more radical-forming initiators, wherein the resultant polymer has a glass transition temperature (T.sub.G1) of +30.degree. to +110.degree. C., and wherein the monomer has no further limitation, and
• (b) polymerizing in a second stage 90 to 10 parts by weight of an ethylenically unsaturated monomer or a mixture of ethylenically unsaturated monomers, after at least 80% by weight of the monomer or the mixture of monomers used in the first stage has reacted, in the presence of the polymer obtained in the first stage, wherein the monomer or mixture of monomers used in the second stage is chosen such that an exclusive polymerization of the monomers used in the second stage gives rise to a polymer having a glass transition temperature (T.sub.G2) of -60.degree. to +20.degree. C., the reaction conditions being chosen such that the resultant emulsion polymer has a number average molecular mass of 200,000 to 2,000,000, and the resultant emulsion polymer has a hydroxyl value of 2 to 100 and the difference T.sub.G1 -T.sub.G2 is 10 to 170.degree. C., the monomers having no further limitation.