Matt PU powder coatings

• US 20020045717A1
• Filed: 08/28/2001
• Published: 04/18/2002
• Est. Priority Date: 08/29/2000
• Status: Active Grant

• Current Assignee: Degussa AG (Rag-Stiftung)
• Original Assignee: Degussa AG (Rag-Stiftung)
• Inventors: Grenda, Werner, Weiss, Joern Volker
• Granted Patent: US 6,710,136 B2
• Time in Patent Office: Days
• US Class Current: 525/453
• CPC Class Codes: C08G 18/4208 containing aromatic groups
• CPC Class Codes: C08G 18/4236 containing only aliphatic groups
• CPC Class Codes: C08G 18/792 formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
• CPC Class Codes: C08G 2150/20 Compositions for powder coatings
• 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
• CPC Class Codes: Y10S 525/934 Powdered coating composition

Abstract

A matt polyurethane powder coating material comprises:

A) 3 to 25% by weight of a polyurea;

B) 35 to 75% by weight of at least one polyester synthesized from polyols and 15-100 mol. % of succinic acid or its anhydride, having an OH number of 20-250 mg KOH/g;

C) 7 to 25% by weight of at least one curing agent of a blocked polyisocyanate, isocyanurate, uretdione or a combination thereof having a functionality of at least 2; and

D) 1 to 50% by weight of auxiliaries and additives; wherein from 0.6 to 1.2 NCO groups are available per OH group of the resin.

Claims

1. A matt polyurethane powder coating material, comprising:

A) 3 to 25% by weight of a polyurea;

B) 35 to 75% by weight of at least one polyester synthesized from polyols and 15-100 mol. % of succinic acid or its anhydride, having an OH number of 20-250 mg KOH/g;

C) 7 to 25% by weight of at least one curing agent of a blocked polyisocyanate, isocyanurate, uretdione or a combination thereof having a functionality of at least 2; and

D) 1 to 50% by weight of auxiliaries and additives;

wherein from 0.6 to 1.2 NCO groups are available per OH group of the resin.

2. The matt polyurethane powder coating material as claimed in claim 1, wherein the polyurea A) comprises

at least one at least difunctional isocyanate and

at least one at least difunctional amine, the polyurea having a NCO/NH₂ ratio of 0.9-1.1:

1.

3. The matt polyurethane powder coating material as claimed in claim 1, wherein the polyurea comprises an isocyanate and/or isocyanurate.

4. The matt polyurethane powder coating material as claimed in claim 3, wherein the isocyanate or isocyanurate is selected from the group consisting of IPDI, HDI and/or HMDI.

5. The matt polyurethane powder coating material as claimed in claim 1, wherein the polyurea comprises aliphatic, (cyclo)aliphatic, cycloaliphatic, aromatic diamines and/or polyamines having 5-18 carbon atoms.

6. The matt polyurethane powder coating material as claimed in claim 5, wherein IPDI is present as an amine.

7. The matt polyurethane powder coating material as claimed in claim 1, wherein the polyester B) is synthesized from at least one polyol selected from the group consisting of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, cyclohexanediol, neopentyl glycol, 1,4-bis(hydroxymethyl) cyclohexane.

8. The matt polyurethane powder coating material as claimed in claim 1, wherein the polyester B) is synthesized from one the following acids in addition to succinic acid:

adipic acid, tetrahydrophthalic acid, isophthalic acid, terephthalic acid, trimellitic acid and pyromellitic acid.

9. The matt polyurethane powder coating material as claimed in claim 1, wherein the polyester B) has a molecular weight of 3,000 to 8,000.

10. The matt polyurethane powder coating material as claimed in claim 9, wherein the polyester B) has a molecular weight of 4,000 to 5,000.

11. The matt polyurethane powder coating material as claimed in claim 1, wherein curing agent C) is a blocked polyisocyanate, a blocked isocyanurate and/or a uretdione of the diisocyanates IPDI, HDI and/or HMDI.

12. The matt polyurethane powder coating material as claimed in claim 11, wherein the curing agent C) is blocked with a blocking agent selected from the group consisting of caprolactam, triazoles, oximes, and pyrazoles.

13. The matt polyurethane powder coating material as claimed in claim 1, wherein the ratio of OH group-containing polyester to curing agent is such that from 0.6 to 1.2 NCO groups are available per OH group of the polyester.

14. The matt polyurethane powder coating material as claimed in claim 13, wherein from 0.8 to 1.0 NCO groups are available per OH group of the polyester.

15. The matt polyurethane powder coating material as claimed in claim 1, wherein said auxiliaries are leveling agents, pigments, fillers and catalysts.