Water soluble or dispersible polyurethanes, a process for their preparation and their use for coating substrates

• US 4,764,553 A
• Filed: 12/01/1987
• Issued: 08/16/1988
• Est. Priority Date: 12/04/1986
• Status: Expired due to Term

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Pedain, Josef, Noll, Klaus, Mosbach, Jurgen
• Primary Examiner(s): WELSH JR, MAURICE
• Application Number:
  US07/127,340
• Time in Patent Office: 259 Days
• Field of Search: 524/591, 524/839, 524/840, 528/71
• US Class Current: 524/591
• CPC Class Codes: C08G 18/0823 containing carboxylate salt groups or groups forming them
• CPC Class Codes: C08G 18/2805 Compounds having only one group containing active hydrogen vinylpolymers having terminal groups containing active hydrogen C08G18/62
• CPC Class Codes: C08G 18/5042 containing ureum groups
• CPC Class Codes: C08G 18/7818 containing ureum or ureum derivative groups
• CPC Class Codes: C08G 18/8061 masked with compounds having only one group containing active hydrogen

Abstract

The present invention is directed to water dispersible or soluble polyurethanes containing about 0.5 to 30% by weight, based on the weight of the polyurethanes, of ethylene oxide units present in lateral or terminal polyether chains, characterized in that in addition to these ethylene oxide units the polyurethanes contain, as further hydrophilic centers, about 0.1 to 120 milliequivalents, per 100 g of solids content, of carboxylate groups in the form of built-in structural units corresponding to the general formula ##STR1## wherein R denotes an alkyl group having 1 to 4 carbon atoms and the total quantity of carboxylate groups and ethylene oxide units present in lateral or terminal chains is calculated to ensure the solubility or dispersibility of the polyurethanes in water.

The present invention also relates to a process for the preparation of these polyurethanes and to their use for coating substrates.

Claims

1. A water-soluble or dispersible polyurethane containing about 0.5 to 30% by weight, based on the weight of the polyurethane, of chemically incorporated, hydrophilic ethylene oxide units arranged in lateral and/or terminal polyether chains to said polyurethane. and about 0.1 to 120 milliequivalents, per 100 g of solids content, of chemically incorporated carboxylate groups corresponding to the formula ##STR8## wherein R denotes an alkyl group with 1 to 4 carbon atoms and said hydrophilic ethylene oxide units and said carboxylate groups are present in an amount sufficient to ensure the solubility or dispersibility of said polyurethane in water.

2. The polyurethane of claim 1 wherein said alkyl group is a methyl group.

9. A coated substrate prepared from the water-soluble or dispersible polyurethane of claim 1.

3. A process for the preparation of a water-soluble or dispersible polyurethane which comprises

(a) an organic polyisocyanate with

(b) an organic compound having a molecular weight of 300 to about 5000 and at least two isocyanate reactive groups,

(c) a chain lengthening agent or cross-linking agent comprising a compound having a molecular weight of 32 to 299 and at least two isocyanate reactive groups,

(d) a component containing ethylene oxide units within polyether chains comprising a member selected from the group consisting of

(1) diisocyanates having lateral polyether chains containing ethylene oxide units and compounds containing isocyanate reactive groups which are difunctional in isocyanate polyaddition reactions and having lateral polyether chains containing ethylene oxide units,

(2) monoisocyanates having polyether chains containing ethylene oxide units and compounds containing one isocyanate reactive group which are monofunctional in isocyanate polyaddition reactions and having polyether chains containing ethylene oxide units, and

(3) mixtures of (1) and (2),

(e) a dihydroxymonocarboxylic acid corresponding to the formula ##STR9## wherein R is an alkyl group having 1 to 4 carbon atoms, (f) optionally an organic compound which contains one isocyanate reactive group, is monofunctional in isocyanate polyaddition reactions and is free from ethylene oxide units,

in at least one stage at an equivalent ratio of isocyanate groups to isocyanate reactive groups of about 0.8:

1 to 2;

1, conducting at least a portion of the last stage of said reaction in the presence of an isocyanate inert, water-miscible solvent to produce a polyurethane having an isocyanate group content of 0 to about 10% by weight and subsequently converting at least a portion of the carboxyl groups present to carboxylate groups with ammonia, said starting materials being selected such that said polyurethane contains about 0.5 to 30% by weight, based on the solids content, of chemically incorporated hydrophilic ethylene oxide units arranged in lateral and/or terminal polyether chains and about about 0.1 to 120 milliequivalents of carboxylate groups per 100 g of solids content, wherein said hydrophilic ethylene units and said said carboxylate groups are present in an amount sufficient to ensure the dispersibility or solubility of said polyurethane.

4. The process of claim 3, wherein said ammonia is in the form of an aqueous solution.

5. The process of claim 3, wherein R is a methyl group.

6. The process of claim 4, wherein R is a methyl group.

7. The process of claim 3, which comprises adding water to said solution before, during or after the addition of ammonia and optionally subsequently removing at least a portion of said solvent by distillation.

8. The process of claim 6, which comprises adding water to said solution before, during or after the addition of ammonia and optionally subsequently removing at least a portion of said solvent by distillation.