Process for the preparation of aqueous dispersions containing both blocked polyisocyanates and polyhydroxyl compounds

• US 5,300,556 A
• Filed: 11/17/1992
• Issued: 04/05/1994
• Est. Priority Date: 07/23/1991
• Status: Expired due to Fees

• Current Assignee: Miles, Inc. (Bayer AG)
• Original Assignee: Miles, Inc. (Bayer AG)
• Inventors: Rosthauser, James W., Tirpak, Robin E.
• Primary Examiner(s): Michl, Paul R.
• Assistant Examiner(s): NILAND, PATRICK DENNIS
• Application Number:
  US07/977,330
• Time in Patent Office: 504 Days
• Field of Search: 524/591, 528/44, 528/45, 528/65, 528/85
• US Class Current: 524/591
• CPC Class Codes: C08G 18/0804 Manufacture of polymers containing ionic or ionogenic groups
• CPC Class Codes: C08G 18/0866 the dispersing or dispersed phase being an aqueous medium
• CPC Class Codes: C08G 18/706 the liquid medium being water
• CPC Class Codes: C08G 18/8058 with compounds of C08G18/3819
• CPC Class Codes: C08G 18/8064 with monohydroxy compounds
• CPC Class Codes: C08G 18/807 with nitrogen containing compounds
• CPC Class Codes: C08G 18/8083 with compounds containing at least one heteroatom other than oxygen or nitrogen

Abstract

The present invention is directed to a process for the preparation of an aqueous dispersion containing both a blocked polyisocyanate and a polyhydroxyl compound by reacting an aqueously dispersed polyisocyanate having an isocyanate content of at least 12% by weight, based on the weight of the polyisocyanate, with a monofunctional blocking agent which is more reactive with isocyanate groups than water at an equivalent ratio of monofunctional blocking groups to isocyanate groups of 0.5:1 to 2:1 in the presence of a polyhydroxyl compound which is either water soluble or water dispersible, wherein the polyhydroxyl compound is present in an amount which is sufficient to provide an equivalent ratio of hydroxyl groups to blocked isocyanate groups of 0.6:1 to 1.25:1.

Claims

1. A process for the preparation of an aqueous dispersion containing both a blocked polyisocyanate and a polyhydroxyl compound which comprises reacting an aqueously dispersed polyisocyanate having an isocyanate content of at least 12% by weight, based on the weight of the polyisocyanate, with a monofunctional blocking agent which is more reactive with isocyanate groups than water at an equivalent ratio of monofunctional blocking groups to isocyanate groups of 0.5:

1 to 2;

1 in the presence of a polyhydroxyl compound which is either water soluble or water dispersible, wherein the polyhydroxyl compound is present in an amount which is sufficient to provide an equivalent ratio of hydroxyl groups to blocked isocyanate groups of 0.6;

1 to 1.25;

1.

2. The process of claim 1 wherein said monofunctional blocking agent comprises an oxime which corresponds to the formula

3. The process of claim 1 wherein said dispersed polyisocyanate is rendered hydrophilic by reaction with a compound containing a lateral or terminal nonionic hydrophilic group.

4. The process of claim 1 wherein said equivalent ratio of monofunctional blocking groups to isocyanate groups is 0.8:

1.0 to 1.2;

1.0.

5. The process of claim 2 wherein said equivalent ratio of monofunctional blocking groups to isocyanate groups is 0.8:

1.0 to 1.2;

1.0.

6. The process of claim 3 wherein said equivalent ratio of monofunctional blocking groups to isocyanate groups is 0.8:

1.0 to 1.2;

1.0.

7. A process for the preparation of an aqueous dispersion containing both a blocked polyisocyanate and a polyhydroxyl compound which comprises reacting an aqueously dispersed polyisocyanate having an isocyanate content of at least 12% by weight, based on the weight of the polyisocyanate, with a monofunctional blocking agent which is more reactive with isocyanate groups than water at an equivalent ratio of monofunctional blocking groups to isocyanate groups of 0.5:

1 to 2;

1 in the presence of a polyhydroxyl compound which is water soluble and has a molecular weight of 62 to less than 400, wherein the polyhydroxyl compound is present in an amount which is sufficient to provide an equivalent ratio of hydroxyl groups to blocked isocyanate groups of 0.6;

1 to 1.25;

1.

8. The process of claim 7 wherein said monofunctional blocking agent comprises an oxime which corresponds to the formula

9. The process of claim 7 wherein said dispersed polyisocyanate is rendered hydrophilic by reaction with a compound containing a lateral or terminal nonionic hydrophilic group.

10. The process of claim 7 wherein said equivalent ratio of monofunctional blocking groups to isocyanate groups is 0.8:

1.0 to 1.2;

1.0.

11. The process of claim 8 wherein said equivalent ratio of monofunctional blocking groups to isocyanate groups is 0.8:

1.0 to 1.2;

1.0.

12. The process of claim 9 wherein said equivalent ratio of monofunctional blocking groups to isocyanate groups is 0.8:

1.0 to 1.2;

1.0.