Powder coating composition, process for producing cured film and coated article

Patent metadata

Field	Value
Publication number	US-11286399-B2
Application number	US-201715619792-A
Country	US
Kind code	B2
Filing date	Jun 12, 2017
Priority date	Jun 29, 2012
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

Provided is a powder coating composition, whereby a cured film excellent in water resistance, chemical resistance and weather resistance, can be formed by single coating operation, wherein a fluorinated resin layer and a polyester layer are layer-separated in the process of melting and curing the powder coating composition. A powder coating composition comprising a fluorinated resin (A), a polyester polymer (B), a curing agent (C) and an ultraviolet absorber (D), wherein the polyester polymer (B) is a polyester polymer comprising units derived from a C8-15 aromatic polybasic carboxylic acid compound and units derived from a C2-10 a polyhydric alcohol compound.

First claim

What is claimed is:

1. A powder coating composition comprising:
a single fluorinated resin (A);
a polyester polymer (B);
a curing agent (C); and
an ultraviolet absorber (D),
wherein the fluorinated resin (A) is a fluorinated polymer having a melting point of at most 200° C. or a fluorinated polymer having a glass transition temperature of from 40 to 150° C.,
wherein the fluorinated resin (A) does not comprise units derived from vinylidene fluoride,
wherein the polyester polymer (B) is a polyester polymer comprising units derived from a C8-15 aromatic polybasic carboxylic acid compound which comprises isophthalic acid and units derived from a C2-10 polyhydric alcohol compound,
wherein the curing agent (C) is selected from the group consisting of a blocked isocyanate curing agent, an amine curing agent, a β-hydroxyalkylamide curing agent, and a triglycidyl isocyanurate, and
wherein a cured film formed from the powder coating composition comprises a polyester polymer layer made from the polyester polymer (B) and a fluorinated resin layer made from the fluorinated resin (A) with the ultraviolet absorber (D) having a concentration in the fluorinated resin layer that is greater than a concentration in the polyester polymer layer.

2. The powder coating composition according to claim 1 , wherein the fluorinated resin (A) is a hydroxyl group-containing fluorinated polymer (A1).

3. The powder coating composition according to claim 1 , wherein the units derived from the aromatic polybasic carboxylic acid compound in the polyester polymer (B) further comprise at least one selected from the group consisting of units derived from phthalic acid, units derived from terephthalic acid, units derived from naphthalenedicarboxylic acid, units derived from trimellitic acid and units derived from pyromellitic acid.

4. The powder coating composition according to claim 1 , wherein the polyester polymer (B) contains from 30 to 60% of units derived from the aromatic polybasic carboxylic acid compound per the total units in the polyester polymer and has a number average molecular weight of from 500 to 5,000.

5. The powder coating composition according to claim 1 , wherein the content ratio of the fluorinated resin (A) to the polyester polymer (B) is from 70/30 to 10/90 by mass ratio.

6. The powder coating composition according to claim 1 , wherein the content of the curing agent (C) is from 10 to 100 parts by mass per 100 parts by mass in total of the fluorinated resin (A) and the polyester polymer (B).

7. The powder coating composition according to claim 1 , further comprising a pigment (E).

8. The powder coating composition according to claim 1 , further comprising a hindered amine light stabilizer (G) having a melting point of from 50 to 250° C.

9. A coated article comprising:
an article body; and
a cured film of the powder coating composition as defined in claim 1 provided on a surface of the article body,
wherein the cured film comprises a fluorinated resin layer made from the fluorinated resin (A) and a polyester polymer layer made from the polyester polymer (B), and
the ultraviolet absorber (D) has a concentration in the fluorinated resin layer that is greater than a concentration in the polyester polymer layer.

10. A process for producing a cured film, comprising:
coating a substrate with the powder coating composition as defined in claim 1 to form a coating film made of a melt of the powder coating composition on the substrate;
reacting reactive components in the powder coating composition; and then
cooling the coating film in the molten state to room temperature for solidification.

11. A coated article comprising: an article body; and a cured film produced by the process as defined in claim 10 on a surface of the article body.

12. The powder coating composition according to claim 1 , wherein the curing agent (C) is a blocked isocyanate curing agent.

13. The powder coating composition according to claim 1 , wherein the powder coating composition comprises only one type of curing agent (C).

14. The powder coating composition according to claim 1 , wherein the cured film is formed by heating and melting at from 170 to 210° C. and then cooling.

15. A powder coating composition comprising:
a hydroxyl group-containing fluorinated polymer (A1);
a polyester polymer (B);
a blocked isocyanate curing agent (C1); and
an ultraviolet absorber (D1) which is selected from the group consisting of an inorganic ultraviolet absorber and an organic ultraviolet absorber,
wherein the organic ultraviolet absorber is non-oligomeric and has a molecular weight of from 200 to 1,000 and a melting point of from 50 to 150° C.,
wherein the hydroxyl group-containing fluorinated polymer (A1) has a melting point of at most 200° C. or a glass transition temperature of from 40 to 150° C.
wherein the polyester polymer (B) is a polyester polymer comprising units derived from a C8-15 aromatic polybasic carboxylic acid compound which comprises isophthalic acid and units derived from a C2-10 polyhydric alcohol compound, and
wherein a cured film formed from the powder coating composition comprises a polyester polymer layer made from the polyester polymer (B) and a fluorinated resin layer made from the hydroxyl group-containing fluorinated polymer (A1) with the ultraviolet absorber (D1) having a concentration in the fluorinated resin layer that is greater than a concentration in the polyester polymer layer.

16. A coated article comprising:
an article body; and
a cured film of the powder coating composition as defined in claim 15 provided on a surface of the article body,
wherein the cured film comprises a fluorinated resin layer made from the hydroxyl group-containing fluorinated polymer (A1) and a polyester polymer layer made from the polyester polymer (B), and
the ultraviolet absorber (D1) has a concentration in the fluorinated resin layer that is greater than a concentration in the polyester polymer layer.

17. The powder coating composition according to claim 15 , wherein the powder coating composition comprises only one type of curing agent (C).

18. The powder coating composition according to claim 15 , wherein the hydroxyl group-containing fluorinated polymer (A1) is the only fluorinated resin present, and
wherein the hydroxyl group-containing fluorinated polymer (A1) does not comprise units derived from vinylidene fluoride.

19. The powder coating composition according to claim 15 , wherein the organic ultraviolet absorber has a molecular weight of from 200 to 629.8.

Assignees

• Agc Inc

Inventors

• Saito Shun
• Uchida Kouji

Classifications

• C09D7/41

  Organic pigments; Organic dyes · CPC title

• C09D127/16 Primary

  Homopolymers or copolymers of vinylidene fluoride · CPC title

• C08K5/005

  Stabilisers against oxidation, heat, light, ozone · CPC title

• C09D5/03

  Powdery paints · CPC title

• C09D175/04 Primary

  Polyurethanes · CPC title