Composition of diepoxy resin modified with monofunctional organic material and dicarboxylic acid and crosslinker
A protective crosslinkable coating composition comprising modified epoxy resin and crosslinker the modified epoxy resin being the reaction product, by weight, of i) from 80 to 99.9 parts of di-epoxy resin of epoxy equivalent weight from 500 to 5000 and formed from the reaction of bis phenol A diglycidyl ether and bis phenol A and ii) from 0.1 to 20 parts of reactive material characterised in that a) the di-epoxy resin contains minor amounts of resin components of molecular weight less than 1000 Daltons, and the reactive material comprises b) mono-functional organic material of molecular weight at: least 100 Daltons having one moiety capable of reacting with the epoxy moieties of the di-epoxy resin and c) dicarboxylic acid of molecular weight less than 300 Daltons having two moieties capable of reacting with the epoxy moieties of the di-epoxy resin.
1. A protective crosslinkable coating composition comprising modified epoxy resin and crosslinker, the modified epoxy resin being the reaction product of
i) from 80 to 99.9 parts of di-epoxy resin of epoxy equivalent weight from 500 to 5000 and formed from the reaction of bisphenol A diglycidyl ether and bisphenol
A and
ii) from 0.1 to 20 parts by weight of a reactive material characterised in that
a) the di-epoxy resin contains minor amounts of resin components of molecular weight less than 1000 Daltons and the reactive material comprises
b) a mono-functional organic material of molecular weight at least 100 Daltons having one moiety capable of reacting with the epoxy moieties of the di-epoxy resin and
c) a dicarboxylic acid of molecular weight less than 300 Daltons having two moieties capable of reacting with the epoxy moieties of the di-epoxy resin and where the ratio of mono-functional organic material to dicarboxylic acid calculated on a molar basis is from 3:1 to 12:1.
2. A protective crosslinkable coating composition comprising modified epoxy resin and crosslinker the modified epoxy resin being the reaction product, by weight, of
i) from 80 to 99.9 parts by weight of a di-epoxy resin of epoxy equivalent weight from 500 to 5000 and formed from the reaction of bisphenol A diglycidyl ether and bisphenol A and
ii) from 0.1 to 20 parts by weight of a reactive material characterised in that
a) the di-epoxy resin contains minor amounts of resin components of molecular weight less than 1000 Daltons and the reactive material comprises
b) a mono-functional organic material of molecular weight at least 100 Daltons having one moiety capable of reacting with the epoxy moieties of the di-epoxy resin and
c) a tartaric acid having two moieties capable of reacting with the epoxy moieties of the di-epoxy resin.
3. A coating composition according to claim 1 characterised in that the resin component of molecular weight less than 1000 Daltons comprises bisphenol A diglycidyl ether.
4. A coating composition according to claim 3 characterised in that the amount of bisphenol A diglycidyl ether extractable from a crosslinked coating of the coating composition is less than 0.3 micrograms/dm 2 .
5. A coating composition according to claim 1 characterised in that the mono-functional organic material is a mono-carboxylic acid.
6. A coating composition according to claim 5 characterised in that the mono-carboxylic acid is tetradecanoic acid.
7. A coating composition according to any one of claim 3 characterised in that the di-carboxylic acid is tartaric acid.
8. A coating composition according to claim 1 characterised in that the amount of reactive material comprises from 1 to 20% by weight of the modified epoxy resin.
9. A coating composition according to claim 1 characterised in that the modified epoxy resin has at least 30% of the number of epoxy groups as on the diepoxy resin from which it is derived.
10. A process for producing the modified epoxy resin as defined in claim 1 comprising the steps of causing a diepoxy resin of epoxy equivalent weight of from 500 to 5000, formed by the reaction of bisphenol A diglycidyl ether and bisphenol A and containing minor amounts of resin components of molecular weight less than 1000 Daltons to react with a mono-functional organic material of molecular weight at least 100 Daltons and a dicarboxylic acid of molecular weight less than 300 Daltons.
11. A process according to claim 10 characterised in that the mono-functional organic material is reacted with the diepoxy resin in a first step, the resulting product being reacted with the dicarboxylic acid in a later step.
12. A metal container coated with the coating composition according to claim 1 .
13. A process of producing a crosslinked coating on a metal container characterised in that it comprises the steps of applying a coating according to claim 1 and causing the coating to crosslink.
14. A modified epoxy resin as defined in claim 1 .
15. A modified epoxy resin for reducing the amount of bisphenol A diglycidyl ether extractable from a crosslinked coating composition on the interior surface of a metal container to less than 0.3 micrograms/dm, said modified epoxy resin being as defined in claim 14 .
16. A coating composition according to claim 2 characterised in that the resin component of molecular weight less than 1000 Daltons comprises bisphenol A diglycidyl ether.
17. A coating composition according to claim 16 characterised in that the amount of bisphenol A diglycidyl ether extractable from a crosslinked coating of the coating composition is less than 0.3 micrograms/dm 2 .
18. A coating composition according to claim 2 characterised in that the mono-functional organic material is a mono-carboxylic acid.
19. A coating composition according to claim 18 characterised in that the mono-carboxylic acid is tetradecanoic acid.
20. A coating composition according to claim 2 characterised in that the amount of reactive material comprises from 1 to 20% by weight of the modified epoxy resin.
21. A coating composition according to claim 2 characterised in that the modified epoxy resin has at least 30% of the number of epoxy groups as on the diepoxy resin from which it is derived.
22. A process for producing the modified epoxy resin as defined in claim 2 comprising the steps of causing a diepoxy resin of epoxy equivalent weight of from 500 to 5000, formed by the reaction of bisphenol A diglycidyl ether and bis phenol A and containing minor amounts of resin components of molecular weight less than 1000 Daltons to react with a mono-functional organic material of molecular weight at least 100 Daltons and a dicarboxylic acid of molecular weight less than 300 Daltons.
23. A process according to claim 22 characterised in that the mono-functional organic material is reacted with the diepoxy resin in a first step, the resulting product being reacted with the tartaric acid in a later step.
24. A metal container coated with the coating composition according to claim 2 .
25. A process of producing a crosslinked coating on a metal container characterised in that it comprises the steps of applying a coating according to claim 2 and causing the coating to crosslink.
26. A modified epoxy resin as defined in claim 2 .
27. A protective crosslinkable coating composition of claim 1 wherein the dicarboxylic acid is selected from dicarboxylic acids having a molecular weight less than from 30 to 299 or from 130 to 170.
28. A protective crosslinkable coating composition of claim 1 wherein the di-carboxylic acid is selected from succinic acid, maleic acid and phthalic acid.