Claims
- 1. A powder coating wherein the binding agent is composed of a homogeneous mixture of a tri-epoxy compound and a polyester containing carboxyl groups, wherein said mixture contains between 1.4 and 5.3 wt. % of a tri-epoxy compound, and from 94.7 to 98.6 wt. % of a polyester of an aromatic dicarboxylic acid and an aliphatic diol having the following combination of properties: (a) an acid number between 10 and 26 mg KOH/g, (b) a hydroxyl number that is smaller than 15 mg KOH/g, (c) a theoretical number-average molecular weight between 4,500 and 12,500 and (d) a glass transition temperature between 40.degree. and 85.degree. C.
- 2. A polyester according to claim 1, wherein said acid number is between 12 and 24 mg KOH/g.
- 3. A polyester according to claim 1 wherein said hydroxyl number is 5 mg KOH/g at a maximum.
- 4. A polyester according to claim 1, wherein said theoretical number-average molecular weight is between 5,000 and 10,000.
- 5. A polyester according to claim 1, wherein said glass transition temperature of the polyester is between 50.degree. and 70.degree. C.
- 6. A polyester according to claim 1, wherein said average carboxyl functionality of the polyester is between 2 and 3.
- 7. A polyester according to claim 1, wherein said average carboxyl functionality of the polyester is between 2.2 and 2.8.
- 8. A polyester according to claim 1, wherein said dicarboxylic acid mixture consists of at least 50 wt. % of isophthalic acid and/or terephthalic acid.
- 9. A polyester according to claim 1, wherein said dicarboxylic acid mixture consists of at least 70 mol. % of isophthalic acid and/or terephthalic acid.
- 10. A polyester according to claim 1, wherein said aliphatic diol mixture consists of at least 50 mol. % of neopentyl glycol and propylene glycol.
- 11. A polyester according to claim 1, wherein said polyester contains a compound which has at least 4 methylene groups in an amount of up to 15 mol. %.
- 12. A powder coating according to claim 10, wherein the weight percentage of said tri-epoxy compound is between 1.6 and 4.9.
- 13. A powder coating according to claim 10 wherein said tri-epoxy compound is triglycidyl isocyanurate.
- 14. A polyester according to claim 1 wherein said acid number is between 12 and 24 mg KOH/g, said hydroxyl number is 5 mg KOH/g at a maximum, said theoretical number-average molecular weight is between 5,000 and 10,000, said glass transition temperature of the polyester is between 50.degree. and 70.degree. C. and said average carboxyl functionality of the polyester is between 2 and 3.
- 15. A polyester according to claim 14 wherein said dicarboxylic acid mixture consists of at least 50 wt. % of isophthalic acid and/or terephthalic acid.
- 16. A polyester according to claim 14 wherein said dicarboxylic acid mixture consists of at least 70 mol. % of isophthalic acid and/or terephthalic acid.
- 17. A polyester according to claim 14 wherein said aliphatic diol mixture consists of at least 50 mol. % of neopentyl glycol and propylene glycol.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8204205 |
Oct 1982 |
NLX |
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Parent Case Info
This is a division of application Ser. No. 478,546, filed Mar. 24, 1983, now U.S. Pat. No. 4,471,108, granted Sept. 11, 1984.
US Referenced Citations (5)
Divisions (1)
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Number |
Date |
Country |
Parent |
478546 |
Mar 1983 |
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