Abstract: [Problem] In a coating method of a two-coat one-bake system where a clear coat paint is coated after a base coat paint is coated, then these two coated layers are simultaneously hardened, adhesive strength between the two coated layers is to increase in comparison with the conventional method. [Solution] Provided is a coating method; A specific hardener is used in the clear coat paint. The hardener is one containing a polyisocyanate derived from 1,6-hexamethylene diisocyanate, satisfying all the following conditions: 1) Hardener does not virtually include diisocyanate monomer, 2) Viscosity of hardener is not more than 1000 mPa·s/23° C., 3) Content of HDI trimer in hardener is not less than 60 weight %, and 4) Content of HDI dimer in hardener is less than 10 weight %.

Abstract: [Problem] To increase adhesive strength between an aqueous base coat layer and a clear coat layer in a coating method by a two-coat one-bake system where an aqueous base coat paint is coated, then a clear coat paint is coated, and these two coated films are simultaneously hardened, in comparison with the conventional method. [Solution] Provided is a coating method using a specific hardener in a clear coat paint. Namely, the hardener is characterized in that (1) it includes a reaction product of (i) a derivative of 1,6-hexamethylene diisocyanate including a trimer and virtually not including a diisocyanate monomer, and (ii) a compound having both an active hydrogen and a hydrophilic group; and (2) viscosity at 23° C. is not more than 1,000 mPa·s. The compound having both an active hydrogen and a hydrophilic group herein is a compound having an active hydrogen-containing group and a sulfo group represented by formula (I), and preferably the sulfo group in a hardener is neutralized with a tertiary amine.

Abstract: [Problem] In a coating method of a two-coat one-bake system where a clear coat paint is coated after a base coat paint is coated, then these two coated layers are simultaneously hardened, adhesive strength between the two coated layers is to increase in comparison with the conventional method. [Solution] Provided is a coating method; A specific hardener is used in the clear coat paint. The hardener is one containing a polyisocyanate derived from 1,6-hexamethylene diisocyanate, satisfying all the following conditions: 1) Hardener does not virtually include diisocyanate monomer, 2) Viscosity of hardener is not more than 1000 mPa·s/23° C., 3) Content of HDI trimer in hardener is not less than 60 weight %, and 4) Content of HDI dimer in hardener is less than 10 weight %.

Abstract: [Problem] To increase adhesive strength between an aqueous base coat layer and a clear coat layer in a coating method by a two-coat one-bake system where an aqueous base coat paint is coated, then a clear coat paint is coated, and these two coated films are simultaneously hardened, in comparison with the conventional method. [Solution] Provided is a coating method using a specific hardener in a clear coat paint. Namely, the hardener is characterized in that (1) it includes a reaction product of (i) a derivative of 1,6-hexamethylene diisocyanate including a trimer and virtually not including a diisocyanate monomer, and (ii) a compound having both an active hydrogen and a hydrophilic group; and (2) viscosity at 23° C. is not more than 1,000 mPa·s. The compound having both an active hydrogen and a hydrophilic group herein is a compound having an active hydrogen-containing group and a sulfo group represented by formula (I), and preferably the sulfo group in a hardener is neutralized with a tertiary amine.

Abstract: An aliphatic polyisocyanate prepolymer obtained by reacting an aliphatic isocyanurate group-containing polyisocyanate with a short-chain diol, having a urethane bond content of 3.0% by weight or more based on the weight of the prepolymer and a solubility parameter of 11.8 or more.

Abstract: An aliphatic polyisocyanate prepolymer obtained by reacting an aliphatic isocyanurate group-containing polyisocyanate with a short-chain diol, having a urethane bond content of 3.0% by weight or more based on the weight of the prepolymer and a solubility parameter of 11.8 or more.

Abstract: The present invention relates to a blocked polyisocyanate composition containing A) a blocked polyisocyanate which is the reaction product of i) a polyisocyanate prepared from an aliphatic and/or alicyclic diisocyanate and ii) a malonic acid diester blocking agent containing at least 90 equivalent %, based on the total equivalents of blocking agent, of diisopropyl malonate, and B) a mono-functional active hydrogen-containing compound. The present invention also relates to a one-component coating composition containing these blocked polyisocyanate compositions and a polyhydroxyl compound.