US 5,514,746 AGranted

Process for the production of a multicoat coating, aqueous coating compositions, water-thinnable poly-acrylate resins and process for the preparation of water-thinnable polyacrylate resins

AssigneeBASF Lacke + Farben, AG

InventorsStephan Schwarte, Manfred Dangschat, Manfred Reimann, Carlos Westermann

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Abstract

The invention relates to a process for the production of a multicoat coating in which the aqueous topcoat composition contains a water-thinnable polyacrylate resin which has a hydroxyl value of 40 to 200, an acid value of 20 to 100 and a glass transition temperature (T.sub.G) of -40.degree. C. to +60.degree. C., and can be prepared by adding a mixture (I) of a (meth)acrylic acid ester, a copolymerizable hydroxyl-containing monomer and, if appropriate, a further ethylenically unsaturated monomer to an organic solvent and carrying out free-radical polymerization and adding, at the end of the addition of the mixture (I), a mixture of a monomer containing carboxyl groups and a monomer free from carboxyl groups and continuing the polymerization.

Claims11

Dependent claims

A process for the production of a multicoat protective and/or decorative coating on a substrate surface, in which process

(1) a pigmented basecoat composition is applied to the substrate surface,
(2) a polymer film is formed from the composition applied in stage (1),
(3) a transparent aqueous topcoat composition containing a water-dispersible polyacrylate resin as binder and an amino resin as crosslinking agent is applied to the basecoat obtained in this way and subsequently
(4) the basecoat is baked together with the topcoat,
wherein the topcoat composition contains a water-dispersible polyacrylate resin as binder, which resin is obtained by a two step solution polymerization process including steps (I) and (II),
wherein step (I) includes
adding a mixture of
(a1) a (meth)acrylic acid ester which is copolymerizable with (a2), (a3), (b1) and (b2) and is essentially free from carboxyl groups, or a mixture of such (meth)acrylic acid esters, and
(a2) an ethylenically unsaturated monomer which is copolymerizable with (a1), (a3), (b1) and (b2), contains at least one hydroxyl group per molecule and is essentially free from carboxyl groups, or a mixture of such monomers, and, if appropriate,
(a3) an ethylenically unsaturated monomer which is copolymerizable with (a1), (a2), (b1) and (b2), is essentially free from carboxyl groups and is different from (a1) and (a2), or a mixture of such monomers
to an organic solvent or solvent mixture and carrying out a polymerization in the presence of at least one polymerization initiator, and
step (II) includes
adding, after at least 80% by weight of the mixture consisting of (a1), (a2) and, if appropriate, (a3) has been added, and after at least 80% by weight of the monomers added in step (I) have reacted
(b1) more than 25 and less than 60, preferably 33-50% by weight of an ethylenically unsaturated monomer which contains at least one carboxyl group per molecule and is copolymerizable with (a1), (a2), (a3) and (b2), or a mixture of such monomers, together with
(b2) 40-75% by weight of an ethylenically unsaturated monomer which is free from carboxyl groups and is copolymerizable with (a1), (a2), (a3) and (b1), or a mixture of such monomers,
and carrying out further polymerization, and following polymerization
(III) neutralizing, at least partially, the polyacrylate resin obtained at the end of the polymerization and dispersing it in water, the sum of the proportions by weight of (b1) and (b2) always being 100% by weight and the type and amount of (a1), (a2), (a3), (b1) and (b2) being chosen so that the polyacrylate resin has a hydroxyl value of 40 to 200, preferably 60 to 140, an acid value of 20 to 100, preferably 25 to 50, and a glass transition temperature (T.sub.G) of -40.degree. C. to +60.degree. C., preferably -20.degree. C. to +40.degree. C.

14 more elements

An aqueous coating composition comprising a water-dispersible polyacrylate resin as binder and an amino resin as crosslinking agent, wherein the water-dispersible polyacrylate resin is obtained by a two step polymerization process including steps (I) and (II), wherein step (I) includes

adding a mixture of
(a1) a (meth)acrylic acid ester which is copolymerizable with (a2), (a3), (b1) and (b2) and is essentially free from carboxyl groups, or a mixture of such (meth)acrylic acid esters, and
(a2) an ethylenically unsaturated monomer which is copolymerizable with (a1), (a3), (b1) and (b2), contains at least one hydroxyl group per molecule and is essentially free from carboxyl groups, or a mixture of such monomers, and, if appropriate,
(a3) an ethylenically unsaturated monomer which is copolymerizable with (a1), (a2), (b1) and (b2), is essentially free from carboxyl groups and is different from (a1) and (a2), or a mixture of such monomers
to an organic solvent or solvent mixture and carrying out a polymerization in the presence of at least one polymerization initiator, and
step (II) includes
adding, after at least 80% of the mixture consisting of (a1), (a2) and, if appropriate, (a3) has been added, and after at least 80% by weight of the monomers added in step (I) have reacted
(b1) more than 25 and less than 60, preferably 33-50% by weight of an ethylenically unsaturated monomer which contains at least one carboxyl group per molecule and is copolymerizable with (a1), (a2), (a3) and (b2), or a mixture of such monomers, together with
(b2) 40-75% by weight of an ethylenically unsaturated monomer which is free from carboxyl groups and is copolymerizable with (a1), (a2), (a3) and (b1), or a mixture of such monomers,
and carrying out further polymerization, and
(III) at the end of the polymerization the resultant polyacrylate resin is neutralized, at least partially, and dispersed in water, the sum of the proportions by weight of (b1) and (b2) always being 100% by weight and the type and amount of (a1), (a2), (a3), (b1) and (b2) being chosen so that the polyacrylate resin has a hydroxyl value of 40 to 200, preferably 60 to 140, an acid value of 20 to 100, preferably 25 to 50, and a glass transition temperature (T.sub.G) of -40.degree. C. to +60.degree. C., preferably -20.degree. C. to +40.degree. C.

8 more elements

A water-dispersible polyacrylate resin which is obtained by a two step polymerization process including steps (I) and (II),

wherein step (I) includes
adding a mixture of
(a1) a (meth)acrylic acid ester which is copolymerizable with (a2), (a3), (b1) and (b2) and is essentially free from carboxyl groups, or a mixture of such (meth)acrylic acid esters, and
(a2) an ethylenically unsaturated monomer which is copolymerizable with (a1), (a3), (b1) and (b2), contains at least one hydroxyl group per molecule and is essentially free from carboxyl groups, or a mixture of such monomers, and, if appropriate,
(a3) an ethylenically unsaturated monomer which is copolymerizable with (a1), (a2), (b1) and (b2), is essentially free from carboxyl groups and is different from (a1) and (a2), or a mixture of such monomers
to an organic solvent or solvent mixture and carrying out a polymerization in the presence of at least one polymerization initiator, and
wherein step two includes
adding, after at least 80% of the mixture consisting of (a1), (a2) and, if appropriate, (a3) has been added, and after at least 80% by weight of the monomers added in step (I) have reacted
(b1) more than 25 and less than 60, preferably 33-50% by weight of an ethylenically unsaturated monomer which contains at least one carboxyl group per molecule and is copolymerizable with (a1), (a2), (a3) and (b2), or a mixture of such monomers, together with
(b2) 40-75% by weight of an ethylenically unsaturated monomer which is free from carboxyl groups and is copolymerizable with (a1), (a2), (a3) and (b1), or a mixture of such monomers,
and carrying out further polymerization, and
(III) at the end of the polymerization the resultant polyacrylate resin is neutralized, at least partially, and dispersed in water, the sum of the proportions by weight of (b1) and (b2) always being 100% by weight and the type and amount of (a1), (a2), (a3), (b1) and (b2) being chosen so that the polyacrylate resin has a hydroxyl value of 40 to 200, preferably 60 to 140, an acid value of 20 to 100, preferably 25 to 50, and a glass transition temperature (T.sub.G) of -40.degree. C. to +60.degree. C., preferably -20.degree. C. to +40.degree. C.

9 more elements

A process for the preparation of water-dispersible polyacrylate resins, comprising a two step solution polymerization process, wherein

(I) a mixture of
(a1) a (meth)acrylic acid ester which is copolymerizable with (a2), (a3), (b1) and (b2) and is essentially free from carboxyl groups, or a mixture of such (meth)acrylic acid esters, and
(a2) an ethylenically unsaturated monomer which is copolymerizable with (a1), (a3), (b1) and (b2), contains at least one hydroxyl group per molecule and is essentially free from carboxyl groups, or a mixture of such monomers, and, if appropriate,
(a3) an ethylenically unsaturated monomer which is copolymerizable with (a1), (a2), (b1) and (b2), is essentially free from carboxyl groups and is different from (a1) and (a2), or a mixture of such monomers
is added to an organic solvent or solvent mixture and a polymerization is carried out in the presence of at least one polymerization initiator, and
(II) after at least 80% by weight of the mixture consisting of (a1), (a2) and, if appropriate, (a3) has been added, and after at least 80% by weight of the monomers added in step (I) have reacted
(b1) more than 25 and less than 60, preferably 33-50% by weight of an ethylenically unsaturated monomer which contains at least one carboxyl group per molecule and is copolymerizable with (a1), (a2), (a3) and (b2), or a mixture of such monomers, together with
(b2) 40-75% by weight of an ethylenically unsaturated monomer which is free from carboxyl groups and is copolymerizable with (a1), (a2), (a3) and (b1), or a mixture of such monomers,
are added and further polymerization is carried out and
(III) at the end of the polymerization the resultant polyacrylate resin is neutralized, at least partially, and dispersed in water, the sum of the proportions by weight of (b1) and (b2) always being 100% by weight and the type and amount of (a1), (a2), (a3), (b1) and (b2) being chosen so that the polyacrylate resin has a hydroxyl value of 40 to 200, preferably 60 to 140, an acid value of 20 to 100, preferably 25 to 50, and a glass transition temperature (T.sub.G) of -40.degree. C. to +60.degree. C., preferably -20.degree. C. to +40.degree. C.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/927,428Filed 30 Oct 1992
Priority: DE 40 09 931.828 Mar 1990
Granted: 7 May 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

B05D 7/16
To metal, e.g. car bodies: using synthetic lacquers or varnishes
C08F 265/04
Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined…
C09D 151/003
Coating compositions based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated…:…
B05D
Processes for applying fluent materials to surfaces, in general