Process for the preparation of aqueous polyurethane dispersions, containing from 20 to 50% by weight of an anionic polyurethane having a mean particle size from 1 to 15 micron and providing films with durable low gloss aspect.

Process for the preparation of aqueous polyurethane dispersions, containing from 20 to 50% by weight of an anionic polyurethane having a mean particle size from 1 to 15 micron and providing films with durable low gloss aspect.

The present invention relates to a porous layer structure containing a base material and a polyurethane porous layer formed on the base material, wherein a moisture permeability A of the porous layer structure measured by JIS L1099 A-1 (calcium chloride method) is 2000 to 10000 g/(m.sup.2.Math.24h), a moisture permeability loss rate obtained by a predetermined formula from a moisture permeability B of the base material alone measured by JIS L1099 A-1 (calcium chloride method) and the moisture permeability A is 75% or less, and a peel strength at a bonding surface between the base material and the polyurethane porous layer is 0.7 kgf/inch or more.

The present invention relates to a porous layer structure containing a base material and a polyurethane porous layer formed on the base material, wherein a moisture permeability A of the porous layer structure measured by JIS L1099 A-1 (calcium chloride method) is 2000 to 10000 g/(m.sup.2.Math.24h), a moisture permeability loss rate obtained by a predetermined formula from a moisture permeability B of the base material alone measured by JIS L1099 A-1 (calcium chloride method) and the moisture permeability A is 75% or less, and a peel strength at a bonding surface between the base material and the polyurethane porous layer is 0.7 kgf/inch or more.

An aqueous polyurethane resin dispersion has a non-volatile content of not less than 40% by mass and includes polyurethane resin particles dispersed in water. The polyurethane resin particles contain a polyol component, an isocyanate component, and a hydrophilic alkylene oxide component having at least one active hydrogen group and an alkylene oxide. The content of the hydrophilic alkylene oxide component in the polyurethane resin particles is 1 to 25% by mass. The volume average particle size of the polyurethane resin particles is 0.3 to 5 μm.

An aqueous polyurethane resin dispersion has a non-volatile content of not less than 40% by mass and includes polyurethane resin particles dispersed in water. The polyurethane resin particles contain a polyol component, an isocyanate component, and a hydrophilic alkylene oxide component having at least one active hydrogen group and an alkylene oxide. The content of the hydrophilic alkylene oxide component in the polyurethane resin particles is 1 to 25% by mass. The volume average particle size of the polyurethane resin particles is 0.3 to 5 μm.

The object of the present invention is to provide an aqueous coating composition which exhibits a small viscosity change and can form a coating film having a superior coating film appearance even when the amount of the solvent contained in the aqueous coating composition is reduced due to changes in the coating environment.

The present invention provides an aqueous coating composition comprising an acrylic resin dispersion (A) and a melamine resin (B), wherein the acrylic resin dispersion (A) has a core/shell structure, the acrylic resin dispersion (A) is a dispersion of a solution-polymerization product of a core part preparation monomer (a-1) and a shell part preparation monomer (a-2), wherein the shell part preparation monomer (a-2) comprises an acid group-containing polymerizable monomer, the mass ratio of the core part to the shell part of the acrylic resin dispersion (A) is in the range of core part/shell part=30/70 to 70/30, the shell part of the acrylic resin dispersion (A) has an acid group, and the neutralization rate of the acid groups in the shell part is 50% or more, the weight-average molecular weight of the acrylic resin dispersion (A) is in the range of 10,000 to 70,000, the core part preparation monomer (a-1) has an acid value of 10 mg KOH/g or less, and the shell part preparation monomer (a-2) has an acid value of 10 mg KOH/g or more and 70 mg KOH/g or less, the whole monomer mixture comprising the core part preparation monomer (a-1) and the shell part preparation monomer (a-2) has an acid value of 10 mg KOH/g or more and 30 mg KOH/g or less, the glass transition temperature of the acrylic resin dispersion (A) is in the range of −10 to 60° C., and the melamine resin (B) comprises a hydrophobic melamine resin.

The object of the present invention is to provide an aqueous coating composition which exhibits a small viscosity change and can form a coating film having a superior coating film appearance even when the amount of the solvent contained in the aqueous coating composition is reduced due to changes in the coating environment.

The present invention provides an aqueous coating composition comprising an acrylic resin dispersion (A) and a melamine resin (B), wherein the acrylic resin dispersion (A) has a core/shell structure, the acrylic resin dispersion (A) is a dispersion of a solution-polymerization product of a core part preparation monomer (a-1) and a shell part preparation monomer (a-2), wherein the shell part preparation monomer (a-2) comprises an acid group-containing polymerizable monomer, the mass ratio of the core part to the shell part of the acrylic resin dispersion (A) is in the range of core part/shell part=30/70 to 70/30, the shell part of the acrylic resin dispersion (A) has an acid group, and the neutralization rate of the acid groups in the shell part is 50% or more, the weight-average molecular weight of the acrylic resin dispersion (A) is in the range of 10,000 to 70,000, the core part preparation monomer (a-1) has an acid value of 10 mg KOH/g or less, and the shell part preparation monomer (a-2) has an acid value of 10 mg KOH/g or more and 70 mg KOH/g or less, the whole monomer mixture comprising the core part preparation monomer (a-1) and the shell part preparation monomer (a-2) has an acid value of 10 mg KOH/g or more and 30 mg KOH/g or less, the glass transition temperature of the acrylic resin dispersion (A) is in the range of −10 to 60° C., and the melamine resin (B) comprises a hydrophobic melamine resin.

The present invention relates to compount (I) comprising at least one functional group A and at least one functional group B, wherein the functional groups A has structural formula A: wherein R.sub.1 is H, R.sub.2, R.sub.3 and R.sub.4 are independently chosen from H, methyl or ethyl, m is 1-6; and the functional groups B has structural formula B: R.sub.5 is H or methyl, X is O or NH, Z′ is a polyalkoxy group or an omega-alkoxy polycaprolacton group, Y′ is a collection of atoms covalently connected in linear or branched configuration n″ is 0 or 1, and m′ is an integer from 1-6; with the proviso that the summed amount of the number of functional groups A and the number of functional groups B in compound (I) is from 2-13; and the compound has a molecular weight in the range from 800-10000 Dalton.

##STR00001##

The present invention relates to compount (I) comprising at least one functional group A and at least one functional group B, wherein the functional groups A has structural formula A: wherein R.sub.1 is H, R.sub.2, R.sub.3 and R.sub.4 are independently chosen from H, methyl or ethyl, m is 1-6; and the functional groups B has structural formula B: R.sub.5 is H or methyl, X is O or NH, Z′ is a polyalkoxy group or an omega-alkoxy polycaprolacton group, Y′ is a collection of atoms covalently connected in linear or branched configuration n″ is 0 or 1, and m′ is an integer from 1-6; with the proviso that the summed amount of the number of functional groups A and the number of functional groups B in compound (I) is from 2-13; and the compound has a molecular weight in the range from 800-10000 Dalton.

##STR00001##