Two-component coating compositions

• US 9,458,351 B2
• Filed: 05/03/2012
• Issued: 10/04/2016
• Est. Priority Date: 05/03/2011
• Status: Active Grant

• Current Assignee: Axalta Coating Systems Ip Co Llc (Axalta Coating Systems Ltd.)
• Original Assignee: Axalta Coating Systems Ip Co Llc (Axalta Coating Systems Ltd.)
• Inventors: Becker, Wiebke, Dreger, Katharina, Flosbach, Carmen
• Primary Examiner(s): Walters, Jr., Robert S
• Application Number:
  US14/115,077
• Publication Number:
  US 20140106075A1
• Time in Patent Office: 1,615 Days
• Field of Search: 427/385.5
• US Class Current: 1/1
• CPC Class Codes: C08G 18/22 containing metal compounds
• CPC Class Codes: C08G 18/246 containing also tin-carbon bonds
• CPC Class Codes: C08G 18/6229 Polymers of hydroxy groups containing esters of acrylic or methacrylic acid with aliphatic polyalcohols
• CPC Class Codes: C08G 18/6254 Polymers of alpha-beta ethylenically unsaturated carboxylic acids and of esters of these acids containing hydroxy groups
• CPC Class Codes: C08G 18/6258 the acid groups being esterified with polyhydroxy compounds or epoxy compounds during or after polymerization
• CPC Class Codes: C08G 18/792 formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
• CPC Class Codes: C09D 163/00 Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• CPC Class Codes: C09D 175/04 Polyurethanes

Abstract

Two-component coating compositions include: A) a cross-linkable binder compound having at least one functional group reactive towards isocyanate groups, B) a cross-linking agent having at least one free isocyanate group and C) a catalyst component comprising C1) a catalyst for the for the curing reaction between the functional groups of component A) and the isocyanate groups of component B), the catalyst C1) being an organo-metal compound, and C2) an oligomeric or polymeric binder compound having a glass transition temperature Tg of ≧about 20° C., measured by DSC (differential scanning calorimetry) at a heating rate of 10 K/min. The glass transition temperature Tg of the binder compound C2) is above the temperature at which the two-component coating composition is applied, preferably about 10° C. above the temperature at which the two-component coating composition is applied.

Claims

1. Two-component coating composition, comprising:

A) a cross-linkable binder compound (“

cross-linkable binder compound A)”

) having a functional group reactive towards isocyanate groups,

B) a cross-linking agent having a free isocyanate group and

C) from about 1 to about 10%, by weight, of a catalyst component (“

catalyst component C)”

), based on the total weight of the coating composition, the catalyst component comprising;

C1) a catalyst (“

catalyst C1)”

) for a curing reaction between the functional group of component A) and the isocyanate group of component B), said catalyst being an organo-metal catalyst, and

C2) an oligomeric or polymeric binder compound (“

binder compound C2)”

) having a glass transition temperature Tg of ≧

about 20°

C., measured by DSC (differential scanning calorimetry) at a heating rate of about 10 K/min, wherein the catalyst C1 is passivated by being immobilized in the binder compound C2 at a temperature below the Tg of the binder compound C2.

2. The coating composition of claim 1 wherein the catalyst component C is a latent catalyst such that the binder compound C2 frees the catalyst C1 from being immobilized in the binder compound C2 at a temperature above the Tg of the binder compound C2.

3. The coating composition of claim 1, wherein the glass transition temperature of the binder compound C2) is at least about 20°

C. above an application temperature, wherein the application temperature is from about 15 degrees centigrade to about 25 degrees centigrade.

4. The coating composition of claim 1, wherein the glass transition temperature Tg of the binder compound C2) is ≧

about 30°

C.

5. The coating composition of claim 1, wherein the glass transition temperature Tg of the binder compound C2) is about 20 to about 70°

C.

6. The coating composition of claim 1, wherein the coating composition is a water-based coating composition.

7. The coating composition of claim 1, wherein the catalyst component C) comprises about 0.05 to about 20% by weight of catalyst C1) and about 99.95 to about 80% by weight of binder compound C2), wherein the % by weight are based on the total amount of catalyst component C).

8. The coating composition of claim 7, wherein the catalyst component C) comprises about 0.1 to about 10% by weight of catalyst C1) and about 99.9 to about 90% by weight of binder compound C2), wherein the % by weight are based on the total amount of catalyst component C).

9. The coating composition of claim 1, wherein the organo-metal catalyst C1) comprises a metal salt and/or a metal complex of organic compounds.

10. The coating composition of claim 9, wherein the metal complex comprises ligands selected from the group of beta-diketones, alkyl acetoacetates, alcoholates, and combinations thereof.

11. The coating composition of claim 10, wherein the metal complex comprises aluminum, titanium, zirconium or hafnium.

12. The coating composition of claim 1, wherein the organo-metal catalyst C1) comprises an organo-tin carboxylate.

13. The coating composition of claim 1, wherein the binder compound C2) comprises a (meth)acrylic copolymer, a polyester or a combination thereof.

14. The coating composition of claim 1, wherein the cross-linkable binder compound A) comprises compounds selected from the group comprising hydroxyl-functional compounds, thiol-functional compounds, and combinations thereof.

15. A vehicle body part having thereon a two-component coating composition comprising:

A) a cross-linkable binder compound (“

cross-linkable binder compound A)”

) having a functional group reactive towards isocyanate groups,

B) a cross-linking agent having a free isocyanate group and

C) from about 1% to about 10%, by weight, of a catalyst component (“

catalyst component C)”

), based on the total weight of the coating composition, the catalyst component comprising;

C1) a catalyst (“

catalyst C1)”

) for a curing reaction between the functional group of component A) and the isocyanate group of component B), said catalyst being an organo-metal catalyst, and

C2) an oligomeric or polymeric binder compound (“

binder compound C2)”

) having a glass transition temperature Tg of ≧

about 20°

C., measured by DSC (differential scanning calorimetry) at a heating rate of about 10 K/min, wherein the catalyst C1 is passivated by being immobilized in the binder compound C2 at a temperature below the Tg of the binder compound C2.

16. A process for coating a substrate, the process comprising the steps of:

I) applying a coating layer of a two-component coating composition to a substrate at application temperature T_A, the two-component coating composition comprising;

A) a cross-linkable binder compound (“

cross-linkable binder compound A)”

) having a functional group reactive towards isocyanate groups,

B) a cross-linking agent having a free isocyanate group and

C) from about 1% to about 10%, by weight, of a catalyst component (“

catalyst component C)”

), based on the total weight of the coating composition, the catalyst component comprising;

C1) a catalyst (“

catalyst C1)”

) for a curing reaction between the functional group of component A) and the isocyanate group of component B), said catalyst being an organo-metal catalyst, and

C2) an oligomeric or polymeric binder compound (“

binder compound C2)”

) having a glass transition temperature Tg of ≧

about 20°

C., measured by DSC (differential scanning calorimetry) at a heating rate of about 10 K/min, wherein the catalyst C1) is passivated by being immobilized in the binder compound C2); and

II) curing said coating layer,

wherein the glass transition temperature Tg of the binder compound C2) is above the application temperature T_A.