High-solids coating composition

Patent metadata

Field	Value
Publication number	US-9796880-B2
Application number	US-201414897315-A
Country	US
Kind code	B2
Filing date	Jun 13, 2014
Priority date	Jun 17, 2013
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

The present invention pertains to a coating composition based on a specific epoxy-functional siloxane oligomer and an amine-functional polyorganosiloxane. The coating composition is suitable for use on substrates subjected to outdoor conditions, in particular conditions where a high durability, a high UV resistance, and good anti-corrosive properties are required.

First claim

The invention claimed is:

1. A coating composition made from the admixture of (1) an amine-functional polyorganosiloxane having a number average degree of polymerization of 10 or more, and (2) an epoxy-functional organosiloxane oligomer, wherein the epoxy functional organosiloxane oligomer comprises units selected from the group consisting of:
(R 1 R 2 R 3 SiO 1/2 ) a   (i)

(R 1 R 3 SiO 2/2 ) b   (ii)

(R 1 R 1 SiO 2/2 ) c   (iii)

(R 1 SiO 3/2 ) d   (iv)

(R 3 SiO 3/2 ) e , and  (v)

(SiO 4/2 ) f   (vi)

wherein
each of a, b, c, d, e and f is independently 0 or an integer;
the number average of the number of units a+b+c+d+e+f in the epoxy functional organosiloxane oligomer ranges from 2 to 9;
the number average of a+b+e≧2;
the R 1 groups are the same or different and each represents a monovalent hydrocarbon radical having 1-9 carbon atoms or a C 1 -C 6
alkoxy group,
the R 2 groups are the same or different and each represents represent an OH group or a C 1 -C 6 -alkoxy group;
the R 3 groups are the same or different and each represents a monovalent hydrocarbon radical having 1-11 carbon atoms, each R 3 group substituted with at least one epoxy group;
wherein an average of at least 70% of the units of the epoxy-functional organosiloxane oligomer comprise an R 3 group,
and wherein the amounts of the amine-functional polyorganosiloxane and the epoxy-functional organosiloxane oligomer are such that the ratio of active hydrogen equivalents to epoxy equivalents in the coating composition is between 0.3:1 to 1.1:1.

2. The coating composition according to claim 1 wherein the coating composition has at least one of a solids content of at least 70 weight % and/or or a volatile organic content (VOC) not exceeding 250 g/l, determined according to EPA Federal Method 24.

3. The coating composition according to claim 2 wherein the amine-functional polyorganosiloxane has an active hydrogen equivalent weight of from 100 to 1,500 g/eq.

4. The coating composition according to claim 2 , wherein the epoxy equivalent weight of the epoxy-functional organosiloxane oligomer ranges from 109-430 g/eq.

5. The coating composition according to claim 2 , wherein the coating composition has a viscosity of less than 15 Poise at 25° C., determined using a cone and plate viscometer in accordance with BS 3900 Part A7 2000 (and/or ISO 2884-1 1999) with a shear rate of 10,000 s −1 .

6. The coating composition according to claim 1 wherein the amine-functional polyorganosiloxane has an active hydrogen equivalent weight of from 100 to 1,500 g/eq.

7. The coating composition according to claim 6 , wherein the ratio of active hydrogen equivalents to epoxy equivalents in the coating composition is greater than 0.6:1 but less than 1:1.

8. The coating composition according to claim 6 , wherein an average of less than 50% of the silicon atoms in the amine-functional polyorganosiloxane have bound thereon a hydrocarbon group substituted with an amine-functional group.

9. The coating composition according to claim 1 , wherein the epoxy equivalent weight of the epoxy functional organosiloxane oligomer ranges from 109-430 g/eq.

10. The coating composition according to claim 1 wherein the coating composition hardens to form a coating in ambient conditions.

11. The coating composition according to claim 1 , wherein the coating composition has a viscosity of less than 15 Poise at 25° C., determined using a cone and plate viscometer in accordance with BS 3900 Part A7 2000 (and/or ISO 2884-1 1999) with a shear rate of 10,000 s −1 .

12. The coating composition according to claim 1 , wherein the ratio of active hydrogen equivalents to epoxy equivalents in the coating composition is greater than 0.6:1 but less than 1:1.

13. The coating composition according to claim 1 , wherein an average of less than 50% of the silicon atoms in the amine-functional polyorganosiloxane have bound thereon a hydrocarbon group substituted with an amine-functional group.

14. The coating composition according to claim 1 wherein the amine-functional polyorganosiloxane comprises units selected from the group consisting of
(R 4 3 SiO 1/2 ) a   (i)

(R 4 2 SiO 2/2 ) b   (ii)

(R 4 SiO 3/2 ) c , and  (iii)

(SiO 4/2 ) d   (iv)

wherein R 4 is independently an alkyl group or an aryl group, optionally substituted with an amine group; a has a value of less than 0.4; b has a value of greater than 0.15; c has a value of greater than zero to 0.7; d has a value of less than 0.2; the value of a+b+c+d=1; 3 to 50 mole percent of silicon atoms contain amine functional hydrocarbon groups in units (i), (ii) or (iii); the —NH— equivalent weight of the amine functional polyorganosiloxane is from 100 to 1500; greater than 20 weight percent of unit (ii) is present in the amine functional polyorganosiloxane poly siloxane; less than 10 weight percent of unit (ii) are Me 2 SiO 2/2 units in the amine functional polyorganosiloxane; and greater than 50 weight percent of silicon-bonded R groups are silicon-bonded aryl groups.

15. The coating composition according to claim 1 further comprising one or more components selected from the group consisting of adhesion promoting agents, fillers, pigments, solvents, curing accelerators and additives.

16. The coating composition according to claim 1 , further comprising aluminium flake.

17. A kit comprising, as separate parts, a first part comprising an amine-functional polyorganosiloxane and a second part comprising an epoxy-functional organosiloxane oligomer, wherein the amine-functional polyorganosiloxane and the epoxy-functional organosiloxane are according to claim 1 .

18. A method of coating a substrate comprising mixing the first and second parts of the kit as defined in claim 17 to form a mixture, applying a layer of the mixture to the substrate, and allowing the layer to harden to form a coating.

19. The coating composition according to claim 1 , wherein the coating composition is a primer, an intermediate, a finish or a primer/finish coating.

20. An object coated with the coating composition according to claim 1 .

Assignees

• Akzo Nobel Coatings Int Bv

Inventors

• Wills Trevor Michael
• Beaumont Doug
• Ring David
• Stein Tobias

Classifications

• C09D5/08

  Anti-corrosive paints · CPC title

• C09D183/08 Primary

  containing silicon bound to organic groups containing atoms other than carbon, hydrogen, and oxygen · CPC title

• C08G77/045

  containing less than 25 silicon atoms · CPC title

• C09D5/103

  containing Al · CPC title

• C08G77/14

  containing silicon bound to oxygen-containing groups · CPC title