Aqueous, highly cross-linked two-component polyurethane coating system, method for the production and use thereof
First Claim
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1. An aqueous cross-linked two-component polyurethane coating system formed by a process comprising:
- a) producing a binder component based on an aqueous solution or dispersion of hydroxyfunctional and/or aminofunctional oligourethanes or polyurethanes, whereina1) forming polyurethane preadduct by reacting 10 to 50 parts by weight of a higher-molecular weight polyol component (A)(i) containing two or more hydroxyl groups that are reactive with polyisocyanates and having a molecular mass of 500 to 5000 Daltons and 0 to 5 parts by weight of a low-molecular weight polyol component (A)(ii) containing two or more hydroxyl groups that are reactive with polyisocyanates and having a molecular mass of 50 to 499 Daltons with 2 to 20 parts by weight of a polyisocyanate component (B) comprising at least one polyisocyanate, polyisocyanate derivative or polyisocyanate homologue containing two or more aliphatic or aromatic isocyanate groups with addition of 0 to 6 parts by weight of a solvent component (C), components A and B having an NCO/OH equivalent ratio of 1.25;
1 to 2.5;
1;
a2) forming polyurethane prepolymer by reacting the polyurethane preadduct formed in step al) with 0.1 to 1.5 parts by weight of a low-molecular weight and anionically modifiable polyol component (A)(iii) containing one or more hydroxyl groups that are reactive with polyisocyanates and one or more inert carboxylic acid and/or sulfonic acid group(s) which can be partially or completely converted into carboxylate or sulfonate groups in the presence of bases or are already present in the form of carboxylate and/or sulfonate groups, having a molecular mass of 100 to 499 Daltons and with 0 to 8 parts by weight of a hydroxy functional component (A)(iv) containing two or more hydroxyl groups that are reactive with polyisocyanates and other hydrophilic groups that are inert towards polyisocyanates having a molecular mass of 500 to 5000 Daltons;
a3) forming a multifunctional polyurethane oligomer or polymer by reacting the free isocyanate groups of the polyurethane prepolymer from step a2) with 0.1 to 15 parts by weight of a multifunctional chain stopping component (D) containing three or more hydroxyl groups and/or primary and/or secondary amino groups that are reactive with isocyanate groups and having a molecular mass of 50 to 500 Daltons, one of the hydroxyl groups or one of the amino groups reacts with the polyurethane preadduct, the chain stopping component being in an amount that there is no unreacted polyol in a3 in addition to the oligomer from step a2 and wherein water dispersion of a3 is achieved with conversion and hydrophilization to a salt of not more than about 20 meq/(100)g solid resin of ionic groups;
a4) reacting the multifunctional polyurethane oligomer or polymer from step a3) with 0.1 to 1 parts by weight of a neutralization component (E) to partially or completely neutralize the acidic groups and to form neutralized polyurethane oligomer or polymer; and
a5) dispersing the neutralized polyurethane oligomer or polymer from step a4) in 40 to 60 parts by weight of water which also contains 0 to 50 parts by weight of a formulation component (F) to form a binder component; and
b) reacting the binder component from step a5) with a cross-linking component (H) in a ratio of 3;
1 to 5;
1, wherein the cross-linking component (H) comprises water-dispersible polyisocyanates containing aliphatically and/or cycloaliphatically and/or aromatically bound isocyanate groups which can contain 0 to 20 parts by weight of an organic solvent.
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Abstract
An aqueous highly cross-linked two-component polyurethane coating system is described with reduced hydrophilicity and improved resistance to chemicals which can be obtained by a) producing a binder component based on an aqueous solution or dispersion of low-molecular hydroxyfunctional and/or aminofunctional oligourethanes or polyurethanes and b) by subsequently reacting the binder component a) with a cross-linking component (H) in a ratio of 3:1 to 5:1, wherein water-dispersible polyisocyanates are used as the cross-linking component (H).
8 Citations
41 Claims
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1. An aqueous cross-linked two-component polyurethane coating system formed by a process comprising:
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a) producing a binder component based on an aqueous solution or dispersion of hydroxyfunctional and/or aminofunctional oligourethanes or polyurethanes, wherein a1) forming polyurethane preadduct by reacting 10 to 50 parts by weight of a higher-molecular weight polyol component (A)(i) containing two or more hydroxyl groups that are reactive with polyisocyanates and having a molecular mass of 500 to 5000 Daltons and 0 to 5 parts by weight of a low-molecular weight polyol component (A)(ii) containing two or more hydroxyl groups that are reactive with polyisocyanates and having a molecular mass of 50 to 499 Daltons with 2 to 20 parts by weight of a polyisocyanate component (B) comprising at least one polyisocyanate, polyisocyanate derivative or polyisocyanate homologue containing two or more aliphatic or aromatic isocyanate groups with addition of 0 to 6 parts by weight of a solvent component (C), components A and B having an NCO/OH equivalent ratio of 1.25;
1 to 2.5;
1;a2) forming polyurethane prepolymer by reacting the polyurethane preadduct formed in step al) with 0.1 to 1.5 parts by weight of a low-molecular weight and anionically modifiable polyol component (A)(iii) containing one or more hydroxyl groups that are reactive with polyisocyanates and one or more inert carboxylic acid and/or sulfonic acid group(s) which can be partially or completely converted into carboxylate or sulfonate groups in the presence of bases or are already present in the form of carboxylate and/or sulfonate groups, having a molecular mass of 100 to 499 Daltons and with 0 to 8 parts by weight of a hydroxy functional component (A)(iv) containing two or more hydroxyl groups that are reactive with polyisocyanates and other hydrophilic groups that are inert towards polyisocyanates having a molecular mass of 500 to 5000 Daltons; a3) forming a multifunctional polyurethane oligomer or polymer by reacting the free isocyanate groups of the polyurethane prepolymer from step a2) with 0.1 to 15 parts by weight of a multifunctional chain stopping component (D) containing three or more hydroxyl groups and/or primary and/or secondary amino groups that are reactive with isocyanate groups and having a molecular mass of 50 to 500 Daltons, one of the hydroxyl groups or one of the amino groups reacts with the polyurethane preadduct, the chain stopping component being in an amount that there is no unreacted polyol in a3 in addition to the oligomer from step a2 and wherein water dispersion of a3 is achieved with conversion and hydrophilization to a salt of not more than about 20 meq/(100)g solid resin of ionic groups; a4) reacting the multifunctional polyurethane oligomer or polymer from step a3) with 0.1 to 1 parts by weight of a neutralization component (E) to partially or completely neutralize the acidic groups and to form neutralized polyurethane oligomer or polymer; and a5) dispersing the neutralized polyurethane oligomer or polymer from step a4) in 40 to 60 parts by weight of water which also contains 0 to 50 parts by weight of a formulation component (F) to form a binder component; and b) reacting the binder component from step a5) with a cross-linking component (H) in a ratio of 3;
1 to 5;
1, wherein the cross-linking component (H) comprises water-dispersible polyisocyanates containing aliphatically and/or cycloaliphatically and/or aromatically bound isocyanate groups which can contain 0 to 20 parts by weight of an organic solvent.
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2. An aqueous cross-linked two-component polyurethane coating system formed by a process comprising:
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a) producing a binder component based on an aqueous solution or dispersion of hydroxyfunctional and/or aminofunctional oligourethanes or polyurethanes, wherein a1) forming polyurethane preadduct by reacting 10 to 50 parts by weight of a higher-molecular weight polyol component (A)(i) containing two or more hydroxyl groups that are reactive with polyisocyanates and having a molecular mass of 500 to 5000 Daltons and 0 to 5 parts by weight of a low-molecular weight polyol component (A)(ii) containing two or more hydroxyl groups that are reactive with polyisocyanates and having a molecular mass of 50 to 499 Daltons with 2 to 20 parts by weight of a polyisocyanate component (B) comprising at least one polyisocyanate, polyisocyanate derivative or polyisocyanate homologue containing two or more aliphatic or aromatic isocyanate groups with addition of 0 to 6 parts by weight of a solvent component (C), components A and B having an NCO/OH equivalent ratio of 1.25;
1 to 2.5;
1;a2) forming polyurethane prepolymer by reacting the polyurethane preadduct formed in step a1) with 0.1 to 1.5 parts by weight of a low-molecular weight and anionically modifiable polyol component (A)(iii) containing one or more hydroxyl groups that are reactive with polyisocyanates and one or more inert carboxylic acid and/or sulfonic acid group(s) which can be partially or completely converted into carboxylate or sulfonate groups in the presence of bases or are already present in the form of carboxylate and/or sulfonate groups, having a molecular mass of 100 to 499 Daltons and with 0 to 8 parts by weight of a hydroxy functional component (A)(iv) containing two or more hydroxyl groups that are reactive with polyisocyanates and other hydrophilic groups that are inert towards polyisocyanates having a molecular mass of 500 to 5000 Daltons; a3) forming a multifunctional polyurethane oligomer or polymer by reacting the free isocyanate groups of the polyurethane prepolymer from step a2) with 0.1 to 15 parts by weight of a multifunctional chain stopping component (D) containing three or more hydroxyl groups and/or primary and/or secondary amino groups that are reactive with isocyanate groups and having a molecular mass of 50 to 500 Daltons, one of the hydroxyl groups or one of the amino groups reacts with the polyurethane preadduct, the chain stopping component being in an amount that there is no unreacted polyol in a3 in addition to the oligomer from step a2 and wherein water dispersion of a3 is achieved with conversion and hydrophilization to a salt of not more than about 20 meq/(100)g solid resin of ionic groups, and the hydroxyl and/or amino groups reducing an amount of anionic hydrophilization groups needed to disperse the binder in an aqueous media by at least 50% as compared to a binder not made according to a1 through a3; a4) reacting the multifunctional polyurethane oligomer or polymer from step a3) with 0.1 to 1 parts by weight of a neutralization component (E) to partially or completely neutralize the acidic groups and to form neutralized polyurethane oligomer or polymer; and a5) dispersing the neutralized polyurethane oligomer or polymer from step a4) in 40 to 60 parts by weight of water which also contains 0 to 50 parts by weight of a formulation component (F) to form a binder component, the neutralized polyurethane oligomer or polymer forming micelles having average particle size of from 10 nm to 300 nm in the water; and b) reacting the binder component from step a5) with a cross-linking component (H) in a ratio of 3;
1 to 5;
1, wherein the cross-linking component (H) comprises water-dispersible polyisocyanates containing aliphatically and/or cycloaliphatically and/or aromatically bound isocyanate groups which can contain 0 to 20 parts by weight of an organic solvent. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification