Preparation of binders for coatings, thermosetting coating compositions and their use

Claim 2

An aqueous thermosetting coating composition comprising (A) a water-thinnable curable binder prepared by a process comprising the steps of:

Claim 3

reacting together at a temperature from about 60 to about 170° C. and in the presence of an esterification cata-yst which promotes the selective reaction of epoxy groups with carboxyl groups (a) a poly glycidyl ether having, on average, n epoxy groups per molecule, where 1≦n<2, which comprises the reaction product of a multifunctional polyglycidyl ether having, on average, x epoxy groups per molecule, where x>2, with (x-n) mol of a monofunctional phenol per mol of the multi functional polyglycidyl ether and (b) a dicarboxylic acid in an amount and under conditions effective for reacting essentially all the n epoxy groups per molecule with the dicarboxylic acid and producing a reaction product of (a) and (b) having an acid value in the range of about 20 to about 80 mg KOH/g and (B) a crosslinking compound present in an amount such that the solids weight ratio A:B is from about 95:5 to 60:40.

Claim 4

reacting together at a temperature from about 60 to about 170° C. and in the presence of an esterification cata-yst which promotes the selective reaction of epoxy groups with carboxyl groups (a) a poly glycidyl ether having, on average, n epoxy groups per molecule, where 1≦n<2, which comprises the reaction product of a multifunctional polyglycidyl ether having, on average, x epoxy groups per molecule, where x>2, with (x-n) mol of a monofunctional phenol per mol of the multi functional polyglycidyl ether and (b) a dicarboxylic acid in an amount and under conditions effective for reacting essentially all the n epoxy groups per molecule with the dicarboxylic acid and producing a reaction product of (a) and (b) having an acid value in the range of about 20 to about 80 mg KOH/g and (B) a crosslinking compound present in an amount such that the solids weight ratio A:B is from about 95:5 to 60:40.

Claim 5

The composition of claim 1 in which the crosslinking compound is selected from urea-formaldehyde resins, water-soluble aminoplasts, phenol-formaldehyde resins and block polyisocyanates.

Claim 6

The composition of claim 1 in which the crosslinking compound is a melamine-formaldehyde resin.

Claim 7

The composition of claim 1 in which the solids weight ratio A:B is in the range of from about 85:15 to about 65-35.

Claim 8

The composition of claim 1 in which, in the polyglycidyl ether, 1.3≦n≦2.

Claim 9

The composition of claim 1 in which the polyglycidyl ether is derived from a multifunctional polyglycidyl ether which is an epoxy novolac resin wherein 3≦x≦4.

Claim 10

The composition of claim 1 in which the monofunctional phenol from which the polyglycidyl ether is derived is phenol substituted in the para position by a C 4 -C 12 alkyl substituent.

Claim 11

The composition of claim 1 in which the dicarboxylic acid has a water solubility below 0.3 g/100 g water at 20° C.

Claim 12

The composition of claim 1 in which the dicarboxylic acid is reacted with a mixture of the polyglycidyl ether and a diglycidyl ether.

Claim 13

The composition of claim 9 in which the diglycidyl ether is a diglycidyl ether of Z,2,2-bis(4-hydroxyphenyl)propane having a weight per epoxide of about 70 g to 1500 g.

Claim 14

The composition of claim 1 in which the water-thinnable curable binder has a content of incorporated monofunctional phenol from about 10 to 25 weight percent.

Claim 15

The composition of claim 1 in which the water-thinnable curable binder has an acid value of from about 30 to 50 mg KOH/g.

Claim 16

The composition of claim 1 in which the esterification catalyst is a tertiary amine.