AQUEOUS POLYURETHANE SOLUTIONS FOR POLYURETHANE SYSTEMS

• US 20090264587A1
• Filed: 04/17/2009
• Published: 10/22/2009
• Est. Priority Date: 04/18/2008
• Status: Abandoned Application

• Current Assignee: Bayer Materialscience AG (Covestro AG)
• Original Assignee: Bayer Materialscience AG (Covestro AG)
• Inventors: Melchiors, Martin, Blum, Harald
• Application Number:
  US12/425,573
• Publication Number:
  US 20090264587A1
• Time in Patent Office: Days
• US Class Current: 524/591
• CPC Class Codes: C08G 18/0823 containing carboxylate salt groups or groups forming them
• CPC Class Codes: C08G 18/12 using two or more compounds having active hydrogen in the first polymerisation step
• CPC Class Codes: C08G 18/283 Compounds containing ether groups, e.g. oxyalkylated monohydroxy compounds
• CPC Class Codes: C08G 18/3271 Hydroxyamines
• CPC Class Codes: C08G 18/3275 containing two hydroxy groups
• CPC Class Codes: C08G 18/4211 derived from aromatic dicarboxylic acids and dialcohols
• CPC Class Codes: C08G 18/4238 derived from dicarboxylic acids and dialcohols
• CPC Class Codes: C08G 18/44 Polycarbonates
• CPC Class Codes: C08G 18/4825 Polyethers containing two hydroxy groups C08G18/4833 - C08G18/5096 take precedence
• CPC Class Codes: C08G 18/6659 with compounds of group C08G18/34
• CPC Class Codes: C08G 18/706 the liquid medium being water
• CPC Class Codes: C08G 18/7831 containing biuret groups
• CPC Class Codes: C08G 18/792 formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
• CPC Class Codes: C08G 18/798 containing urethdione groups
• CPC Class Codes: C08L 2666/20 Macromolecular compounds having nitrogen in the main chain according to C08L75/00 - C08L79/00; Derivatives thereof
• CPC Class Codes: C09D 175/06 from polyesters

Abstract

The present invention relates to innovative aqueous polyurethane solutions, to the soluble polyurethanes present therein, to a process for preparing them, and to the use in polyurethane systems.

Claims

1. A process for preparing an aqueous solution of a hydroxy-functional polyurethane containing urea groups and having a hydroxyl group content in the range of from 2% to 10% by weight and a level of urea groups, calculated as —

NH—

CO—

NH—

, derived from amino alcohols having a primary or secondary amino group and at least one hydroxyl group in the range of from 3% to 20% by weight, based in each case on the weight of said hydroxy-functional polyurethane containing urea groups, comprising

preparing an NCO-functional prepolymer by single-stage or multi-stage reaction of

a) at least one hydroxy- and/or amino-functional hydrophilicizing agent having at least one acid group and/or the salt of an acid group, or having at least one tertiary amino group and/or the salt of a tertiary amino group;

b) at least one polyol;

c) at least one polyisocyanate; and

d) optionally, other hydroxy- and/or amino-functional compounds, different from a), b), and e);

and reacting said NCO-functional prepolymer with

e) an amino alcohol component comprising an amino alcohol having a primary or secondary amino group and at least one hydroxyl group, wherein the fraction of amino alcohols having a secondary amino group, based on the total amount of e), is at least 60% by weight;

and dissolving the resulting hydroxy-functional polyurethane containing urea groups in water, wherein said dissolution in water is preceded or accompanied by the reaction of the acid groups or tertiary amino groups of a) with a neutralizing agent.

2. The process of claim 1, wherein c) is composed of

c1) from 27% to 73% by weight of at least one difunctional isocyanate selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate, 2,4-diisocyanatotoluene and/or 2,6-diisocyanatotoluene, and 4,4′

diisocyanatodicyclohexylmethane; and

c2) from 73% to 27% by weight of at least one polyisocyanate having on average more than two isocyanate groups with uretdione, biuret, isocyanurate, allophanate, carbodiimide, iminooxadiazinedione, oxadiazinetrione, urethane, and/or urea structural units based on hexamethylene diisocyanate.

3. The process of claim 1, wherein component e) is an amino alcohol having exclusively one secondary amino group and one or two hydroxyl groups.

4. The process of claim 1, wherein said hydroxy-functional polyurethane containing urea groups is present, prior to dissolution in water, as a non-aqueous dispersion in an organic solvent.

5. An aqueous solution of a hydroxy-functional polyurethane containing urea groups obtained by the process of claim 1.

6. A polyurethane system comprising as component A) the aqueous solution of claim 5.

7. The polyurethane system of claim 6, wherein said polyurethane system further comprises an optionally hydrophilically modified polyisocyanate B).

8. The polyurethane system of claim 7, wherein B) consists of at least one hydrophobic polyisocyanate crosslinker based on hexamethylene diisocyanate.

9. The aqueous solution of claim 5, wherein said aqueous solution is stable to freezing.

10. A water-soluble, hydroxy-functional polyurethane containing urea groups, having a hydroxyl group content in the range of from 2% to 10% by weight and a level of urea groups, calculated as —

NH—

CO—

NH—

, derived from amino alcohols having a primary or secondary amino group and at least one hydroxyl group in the range of from 3% to 20% by weight, based in each case on the weight of said, water-soluble, hydroxy-functional polyurethane containing urea groups, obtained by preparing a NCO-functional prepolymer by reacting

a) at least one hydroxy- and/or amino-functional hydrophilicizing agent having at least one acid group and/or the salt of an acid group, or having at least one tertiary amino group and/or the salt of a tertiary amino group;

b) at least one polyol;

c) at least one polyisocyanate;

d) optionally, other hydroxy- and/or amino-functional compounds, different from a), b), and e);

and reacting said NCO-functional prepolymer with

e) an amino alcohol component, comprising an amino alcohol having a primary or secondary amino group and at least one hydroxyl group, wherein the fraction of amino alcohols having a secondary amino group, based on the total amount of e), is at least 60% by weight;

wherein the tertiary amino groups or acid groups in the resulting water-soluble, hydroxy-functional polyurethane containing urea groups which originate from a) are optionally present in their salt form as a result of whole or partial neutralization.

11. A polyurethane system comprising as component A) the hydroxy-functional polyurethane containing urea groups of claim 10.

12. The polyurethane system of claim 11, wherein said polyurethane system further comprises an optionally hydrophilically modified polyisocyanate B).

13. The polyurethane system of claim 12, wherein B) consists of at least one hydrophobic polyisocyanate crosslinker based on hexamethylene diisocyanate.

14. A polyurethane obtained from the polyurethane system of claim 8.

15. The polyurethane of claim 14, wherein said polyurethane is a paint, coating material, sealant, liquid ink, printing ink, size, adhesion promoter, or reactive diluent applied in one or more layers.

16. A substrate coated with the polyurethane of claim 14.