Adjustable low gloss powder coating compositions

Patent metadata

Field	Value
Publication number	US-10450479-B2
Application number	US-201715727090-A
Country	US
Kind code	B2
Filing date	Oct 6, 2017
Priority date	Apr 10, 2015
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

Thermosetting powdered coating compositions comprising (a) a high Acid Value carboxylic acid functional polyester resin having an Acid Value of at least 100 mg KOH/g and a functionality of at least 4.5, (b) a low Acid Value carboxylic acid functional polyester resin having an Acid Value of 20 to 50 mg KOH/g and a functionality of about 2.5 or less, and (c) a cross-linking agent. The high Acid Value polyester resin is the reaction product of a polycarboxylic acid or its anhydride reacted with a polyester polyol obtained from reacting 0 mol % to 100 mol % of isophthalic acid and/or 0 to 100 mol % terephthalic acid, or a mixture thereof, with a polyol mixture comprising at least one diol and at least one polyol having at least three hydroxyl groups. The thermosetting powdered coating compositions provide coatings with low gloss levels that can be adjusted from a gloss level of less than 1 to 40 or less, when measured at an angle of 60°, by varying the ratios of the high Acid Value and low Acid Value polyester resins in the composition.

First claim

The invention claimed is:

1. A low gloss thermosetting powder coating composition that provides an adjustable level of gloss, the composition comprising:
(I) from 50% to 100% by weight of a binder composition, wherein the binder composition comprises:
(A) at least one carboxylic acid-functional polyester resin A having an Acid Value of at least 100 mg KOH/g and a functionality of at least 4.5, wherein the carboxylic acid-functional polyester resin is the reaction product of
(1) a polyester polyol obtained from (a) a carboxylic acid component comprising 0 mol % to 100 mol % of isophthalic acid and/or 0 to 100 mol % terephthalic acid, or a mixture thereof, reacted with (b) a polyol mixture comprising at least one diol and at least one polyol having at least three hydroxyl groups, the polyester polyol having an OH value of about 60 to about 90 MCI KOH/q, an Acid Value of about 3 to about 20 mg KOH/g, and a functionality of about 2.2 to about 3.5; and
(2) at least one polycarboxylic acid having at least three carboxylic acid groups and/or its anhydride;

(B) at least one carboxylic acid-functional polyester resin B having an Acid Value of about 20 to about 50 mg KOH/g and a functionality of less than about 2.5; wherein the amount of polyester resin A in the binder composition is about 15% to about 45% by weight, and the amount of polyester resin B in the binder composition is about 55% to about 85% by weight, based on the total weight of polyester resins A and B; and
(C) at least one cross-linking agent having functional groups that can react with the carboxylic acid groups of the polyester resins A and B; and

(II) from 0% to 50% by weight of one or more additives; wherein changing the amount of polyester resin A relative to the amount of polyester resin B in the binder composition allows the powder coating composition to provide a level of gloss that is adjustable between less than 1 and about 40 units when measured at an angle of 60°.

2. The composition of claim 1 , wherein polyester resin A has an Acid Value of greater than 120 mg KOH/g.

3. The composition of claim 1 , wherein the polyol having at least three hydroxyl groups is a triol.

4. The composition of claim 3 , wherein the triol is selected from trimethylolpropane, trimethylolethane, glycerol, and mixtures thereof.

5. The composition of claim 1 , wherein the polycarboxylic acid or anhydride used to make polyester resin A is selected from trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, and mixtures thereof.

6. The composition of claim 1 , wherein the at least one diol for preparing polyester resin A comprises neopentyl glycol.

7. The composition of claim 6 , wherein the at least one diol further comprises at least one other diol.

8. The composition of claim 1 , wherein the polyol mixture for preparing polyester resin A does not contain ethylene glycol.

9. The composition of claim 1 , wherein the carboxylic acid component further comprises up to 25 mol % of at least one additional dicarboxylic acid.

10. The composition of claim 9 , wherein the additional dicarboxylic acid is adipic acid.

11. The composition of claim 1 , wherein the cross-linking agent is a p-hydroxyalkylamide group containing compound.

12. The composition of claim 1 , wherein the functionality is 4.7 up to 5.5.

13. The composition of claim 1 , wherein the polyester polyol used to make polyester resin A has an Acid Value of about 3 to about 8 mg KOH/g.

Assignees

• Stepan Co

Inventors

• Stevenson Thomas
• Poole James
• Howell Jackie

Classifications

• C09D167/03 Primary

  the dicarboxylic acids and dihydroxy compounds having the carboxyl - and the hydroxy groups directly linked to aromatic rings · CPC title

• C08G63/127

  Acids containing aromatic rings · CPC title

• C08G2150/20

  Compositions for powder coatings · CPC title

• C09D5/032

  characterised by a special effect of the produced film, e.g. wrinkle, pearlescence, matt finish · CPC title

• C08G63/91

  Polymers modified by chemical after-treatment · CPC title