Method of forming a cured coating film

Claim 1

A method of forming a cured coating film comprising the steps of: A) forming an uncured coating film on a substrate by applying a coating composition comprising as a main component an aromatic epoxy resin derivative containing, per kilogram of said derivative, 0.3 to 10 moles of a polymerizable unsaturated group which is at least one member selected from the group consisting of acryloyl, methacryloyl, itaconoyl, maleoyl, fumaroyl, crotonoyl, acrylamido, methacrylamido, cinnamoyl, vinyl and allyl, and 0.1 to 3 moles of an aprotic onium-containing group of the formula ##STR11## wherein R 1 is hydrogen or a hydrocarbon having 1-8 carbon atoms, which may be substituted with a hydroxyl, alkoxy or ester group or a halogen atom; ##STR12## wherein Z is nitrogen or phosphorus and Y is sulfur; R 2 , R 3 and R 4 are the same or different and are an organic group of 1-14 carbon atoms, wherein R 2 and R 3 , or R 2 , R 3 and R 4 may jointly form a heterocyclic group when taken together with the adjacent nitrogen, phosphorus or sulfur, said aromatic epoxy resin derivative being prepared from an aromatic epoxy resin having a molecular weight of 500 to 5,000 as determined by gel permeation chromatography; wherein said coating composition further comprises a photopolymerization initiator; B) drying to the touch at a temperature between 70° to 100° C. the uncured coating film on the substrate; C) curing the exposed portions of said dried film by irradiating said film with actinic radiation through a photomask; D) developing the irradiated film with water or a dilute aqueous acid solution for dissolution and removal of the unexposed areas of the film; and E) subjecting the developed film to a heat treatment.

Claim 2

A method of forming a cured coating film comprising the steps of: A) forming an uncured coating film on a substrate by applying a coating composition comprising as a main component an aromatic epoxy resin derivative containing, per kilogram of said derivative, 0.3 to 10 moles of a polymerizable unsaturated group which is at least one member selected from the group consisting of acryloyl, methacryloyl, itaconoyl, maleoyl, fumaroyl, crotonoyl, acrylamido, methacrylamido, cinnamoyl, vinyl and allyl, and 0.1 to 3 moles of an aprotic onium-containing group of the formula ##STR11## wherein R 1 is hydrogen or a hydrocarbon having 1-8 carbon atoms, which may be substituted with a hydroxyl, alkoxy or ester group or a halogen atom; ##STR12## wherein Z is nitrogen or phosphorus and Y is sulfur; R 2 , R 3 and R 4 are the same or different and are an organic group of 1-14 carbon atoms, wherein R 2 and R 3 , or R 2 , R 3 and R 4 may jointly form a heterocyclic group when taken together with the adjacent nitrogen, phosphorus or sulfur, said aromatic epoxy resin derivative being prepared from an aromatic epoxy resin having a molecular weight of 500 to 5,000 as determined by gel permeation chromatography; wherein said coating composition further comprises a photopolymerization initiator; B) drying to the touch at a temperature between 70° to 100° C. the uncured coating film on the substrate; C) curing the exposed portions of said dried film by irradiating said film with actinic radiation through a photomask; D) developing the irradiated film with water or a dilute aqueous acid solution for dissolution and removal of the unexposed areas of the film; and E) subjecting the developed film to a heat treatment.