Powdered blend of epoxy resin and anhydride containing hindered nitrogen-containing compound

Claim 2

Powder useful for applying protective coatings comprising a blend of (a) a major proportion by weight of polyglycidyl ether of bisphenol A having a Durrans' softening point between 60° and 130° C., (b) between 50% and 150% of a stoichiometric amount of trimellitic anhydride, and (c) a small amount of catalyst, wherein the improvement comprises: the blend contains by weight of the polyglycidyl ether 0.1 to 5% of at least one hindered nitrogen-containing compound which (1) has an aqueous pKa greater than 3.5, (2) has a boiling point above 125° C., and (3) is soluble in the polyglycidyl ether.

Claim 3

Powder as defined in claim 1 wherein the improvement comprises: the hindered nitrogen-containing compound is a hindered tertiary amine of the formula ##STR3## wherein R 1 and R 2 are aliphatic and R 3 is aromatic, aliphatic or cycloaliphatic.

Claim 4

Powder as defined in claim 2 wherein the improvement comprises: the hindered tertiary amine is N,N-diethylaniline.

Claim 5

Powder as defined in claim 1 wherein the improvement comprises: the hindered nitrogen-containing compound is a heterocycle of the formula ##STR4## wherein each of R' and R" is lower alkyl.

Claim 6

Powder as defined in claim 4 wherein the improvement comprises: the heterocycle is 2,6-dimethyl pyridine.

Claim 7

Powder as defined in claim 1 wherein the improvement comprises: the hindered nitrogen-containing compound catalyzes the epoxy-anhydride reaction and is the sole catalyst of the blend.

Claim 8

Powder as defined in claim 1 wherein the improvement comprises: the blend also contains an unhindered catalytic tertiary amine.

Claim 9

Powder as defined in claim 1 wherein the improvement comprises: the blend also contains a metal salt catalyst.

Claim 10

Powder as defined in claim 1 wherein the improvement comprises: the blend also contains an imidazole catalyst.

Claim 11

Powder as defined in claim 1 wherein the improvement comprises: the blend also contains a copolymer of vinyl acetate and ethylene.

Claim 12

Powder as defined in claim 1 wherein the improvement comprises: the weight of the hindered nitrogen-containing compound is 0.5 to 1% by weight of the polyglycidyl ether.

Claim 13

Powder as defined in claim 1 wherein the improvement comprises: the pK a of the hindered nitrogen-containing compound is within the range of 5 to 9.

Claim 14

Powder as defined in claim 1 wherein the improvement comprises: the hindered nitrogen-containing compound is dissolved into the polyglycidyl ether.

Claim 15

Method of making a powder useful for applying protective coatings comprising the steps of (1) blending (a) a major proportion by weight of polyglycidyl ether of bisphenol A having a Durrans' softening point of 60° to 130° C., (b) trimellitic anhydride, and (c) a catalyst, and (2) pulverizing the blend to provide a powder, wherein the improvement comprises: including in the blend by weight of the polyglycidyl ether 0.1 to 5% of at least one hindered nitrogen-containing compound which (1) has an aqueous pK a greater than 3.5, (2) has a boiling point above 125° C., and (3) is soluble in the polyglycidyl ether.

Claim 16

Method of making a powder useful for applying protective coatings comprising the steps of (1) blending (a) a major proportion by weight of polyglycidyl ether of bisphenol A having a Durrans' softening point of 60° to 130° C., (b) trimellitic anhydride, and (c) a catalyst, and (2) pulverizing the blend to provide a powder, wherein the improvement comprises: including in the blend by weight of the polyglycidyl ether 0.1 to 5% of at least one hindered nitrogen-containing compound which (1) has an aqueous pK a greater than 3.5, (2) has a boiling point above 125° C., and (3) is soluble in the polyglycidyl ether.

Claim 17

Method of making powder as defined in claim 14 wherein the hindered nitrogen-containing compound is dissolved into the polyglycidyl ether before blending it with the trimellitic anhydride.

Claim 18

Polyglycidyl ether of bisphenol A having a Durran's softening point between 60° and 130° C., containing no curing agent, and having dissolved therein 0.1 to 5% of its weight of at least one hindered nitrogen-containing compound which has (1) an aqueous pKa greater than 3.5 and (2) a boiling point above 125° C.

Claim 19

Polyglycidyl ether of bisphenol A having a Durran's softening point between 60° and 130° C., containing no curing agent, and having dissolved therein 0.1 to 5% of its weight of at least one hindered nitrogen-containing compound which has (1) an aqueous pKa greater than 3.5 and (2) a boiling point above 125° C.

Claim 20

Polyglycidyl ether as defined in claim 16 wherein the amount of the hindered nitrogen-containing compound is 0.5 to 1.0% of the weight of the polyglycidyl ether.

Claim 21

Polyglycidyl ether as defined in claim 17 wherein the pKa of the hindered nitrogen-containing compound is betwen 5 and 9.

Claim 22

Polyglycidyl ether as defined in claim 18 wherein the nitrogen-containing compound is a hindered tertiary amine of the formula ##STR5## wherein R 1 and R 2 are aliphatic and R 3 is aromatic, aliphatic or cycloaliphatic.

Claim 23

Polyglycidyl ether as defined in claim 18 wherein the nitrogen-containing compound is a heterocycle of the formula ##STR6## wherein each of R' and R" is lower alkyl.

Claim 24

Polyglycidyl ether as defined in claim 16 having blended therewith a copolymer of vinyl acetate and ethylene in an amount up to 30 parts by weight of the polyglycidyl ether.