Method for making multilayer coating film

• Main Authors: NAGANO TOSHIAKI, SUGAI HIDEO, CHIGA KOKI, FUKUDA TOORU
• Format: Patent
• Language: English
• Published: 18.09.2008
• Subjects: APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TO SURFACES, IN GENERAL; LAYERED PRODUCTS; LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM; PERFORMING OPERATIONS; PROCESSES FOR APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TOSURFACES, IN GENERAL; SPRAYING OR ATOMISING IN GENERAL; TRANSPORTING

This invention provides a multilayer coating film-forming method which comprises applying a first clear paint onto a coating object, applying onto so formed first clear coating film which is either uncured or cured by heating, a second clear paint such that its heat-cured film thickness falls within a range of 2-15 mum, and forming the second clear coating film, (a) the first clear paint and second clear paint comprising hydroxyl-containing resin as the base resin and polyisocyanate compound as the crosslinking agent, and (b) when the coating film formed by applying a paint to a cured film thickness of 40 mum and curing it by heating at 140° C. for 30 minutes is measured of its dynamic viscoelasticity at a frequency of 11 Hz, the first clear paint forming the first clear coating film having a glass transition temperature of lower than 70° C. and tan delta (=loss elastic modulus/storage elastic modulus) at 80° C. of less than 0.4, and the second clear paint forming the second clear coating film having a glass transition temperature of at least 70° C.