# US 5,328,579 A · Method for forming a paint film > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,328,579 A - Document ID: US5328579A - Status: Granted - Kind: A - Application number: 07/970,021 - Filed: 1993-01-25 - Granted: 1994-07-12 - Earliest claimed: 1991-08-08 - Assignees: Kansai Paint Co., Ltd. - Inventors: Takahisa Kasukawa; Teiji Katayama; Ichiro Tabuchi; Mitsuharu Morino; Hiroshi Inoue; Toshio Ohkoshi - Web page: https://patentgrep.com/patent/US5328579A ## CPC - B05D 7/542: {the two layers being cured or baked together} - C09D 5/443: {Polyepoxides} - B05D 1/007: {using an electrostatic field (B05D1/02 - B05D1/16 take precedence)} - B05D 2451/00: Type of carrier, type of coating (Multilayers) - B05D 2504/00: Epoxy polymers - B05D 2508/00: Polyesters - Y10T 428/31522: Next to metal - Y10T 428/31529: Next to metal - B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02) - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method for forming a multilayer paint film comprising the steps of forming an uncured film on a substrate with a cationically depositable paint on a substrate, further coating an aqueous paint on the uncured film of the electrodeposited film in a wet-on-wet manner, and then curing with heating the both films, wherein (i) the electrodeposited film of the cationically electrodepositable paint has a film weight reduction after curing with heating of 10% by weight or less; and wherein (ii) the aqueous paint is composed mainly of (a) a polyester resin optionally modified with a urethane and having an acid value within the range of 10 to 100 and a hydroxyl value within the range of 20 to 300; and (b) a water-soluble or -dispersible amino resin. ## Claims ### Claim 1 A method for forming a multilayer paint film comprising the steps of forming an uncured film on a substrate with a cationically electrodepositable paint on a substrate, further coating an aqueous paint on the uncured film of the electrodeposited film in a wet-on-wet manner, and then curing with heating the both films, wherein (i) the electrodeposited film of the cationically electrodepositable paint has a film weight reduction after curing with heating of 10% by weight or less, the cationically electrodepositable paint comprising (A) a resin having hydroxyl groups and cationic groups, and (D) a blocked polyisocyanate compound being blocked with a blocking agent having a molecular weight of 130 or less as principal components; wherein (ii) the aqueous paint is composed mainly of (a) a polyester resin optionally modified with a urethane and having an acid value within the range of 10 to 100 and a hydroxyl value within the range of 20 to 3000; and (b) a water-soluble or -dispersible amino resin having an imino group. ### Claim 2 (depends on 1) The method of claim 1, wherein said electrodeposited paint film has a weight has a weight reduction by curing with heating of 7% by weight or less. ### Claim 3 (depends on 1) The method of claim 1, wherein said resin (A) has primary hydroxyl groups and cationic groups. ### Claim 4 (depends on 1) The method of claim 1, wherein said resin (A) is a reaction product obtained by reacting a polyepoxide compound obtained from a polyphenol compound and epichlorohydrin with a cationizing agent. ### Claim 5 (depends on 4) The method of claim 4, wherein said polyepoxide compound is polyglycidylether of the polyphenol compound having a number average molecular weight of abut 800 to about 2,000 and an epoxy equivalent of 190 to 2,000. ### Claim 6 (depends on 1) The method of claim 1, said resin (A) has a hydroxyl equivalent within the range of 20 to 5,000. ### Claim 7 (depends on 4) The method of claim 4, said resin (A) has a primary hydroxyl equivalent within the range of 200 to 1,000. ### Claim 8 (depends on 1) The method of claim 1, wherein said resin (A) has an amine value within the range of 3 to 200 calculated as KOH (mg/g solids). ### Claim 9 (depends on 1) The method of claim 1, wherein said blocked polyisocyanate compound (D) is a polyisocyanate compound selected from the group consisting of isophorone diisocyanate and xylylene diisocyanate, said polyisocyanate compound being blocked with a blocking agent having a molecular weight of 130 or less. ### Claim 10 (depends on 9) The method of claim 9, wherein said blocking agent is an oxime type blocking agent. ### Claim 11 (depends on 1) The method of claim 1, wherein said blocked polyisocyanate compound (D) is selected from the group consisting of methyl ethyl ketoxime-diblocked isophorone diisocyanate, and methyl ethyl ketoxime-diblocked xylylene diisocyanate. ### Claim 12 (depends on 1) The method of claim 1, wherein the weight ratio of the solids content of said blocked polyisocyanate compound (D) to said resin (A) is within the range of 0.05 to 1.5. ### Claim 13 (depends on 1) The method of claim 1 wherein said cationically electrodepositable paint further contains at least one metal compound selected from the group consisting of a lead compound, a zirconium compound, a cobalt compound, an aluminum compound, a manganese compound, a copper compound, a zinc compound, an iron compound, a chromium compound and a nickel compound in an amount that the metal content based on the total weight of the resin (A) and the polyisocyanate compound (D) is not more than 10% by weight. ### Claim 14 (depends on 1) The method of claim 1, wherein said polyester resin (a) in said aqueous paint is a urethane-modified polyester resin. ### Claim 15 (depends on 14) The method of claim 14, wherein said urethane-modified polyester resin is a polyester resin modified with a polyisocyanate compound selected from the group consisting of tolylene diisocyanate, xylylene diisocyanate and isophorone diisocyanate. ### Claim 16 (depends on 1) The method of claim 1, wherein said polyester resin (a) has a weight average molecular weight within the range of 1,000 to 20,0000. ### Claim 17 (depends on 1) The method of claim 1, wherein said polyester resin (a) is a polyester resin rendered water-soluble or -dispersible by neutralization with a basic substance of at least 20% of an acid group existing in the polyester resin. ### Claim 18 (depends on 1) The method of claim 1, wherein said aqueous paint contains 50 to 90% by weight of said polyester resin and 50 to 10% by weight of said amino resin based on total weight of said polyester resin (a) and said amino resin (b). ### Claim 19 (depends on 1) The method of claim 1, wherein said curing with heating is carried out at a temperature of 70.degree. to 250.degree. C.