Method for formation of multi-layered coating film, and coated article

Abstract

Disclosed are: a method for forming a metallic multi-layered coating film having high luster, high hardness and high adhesion on a metallic material (MM); and a coated article having a coating film produced by the method. Specifically disclosed are: a method for forming a multi-layered coating film, which comprises the steps of: applying a base coat paint (BC) on the surface of an MM; applying a clear coat paint (CC) on the BC; and baking the BC and the CC simultaneously; wherein the BC comprises a melamine resin (MR), a hydroxyl-containing acrylic resin (AR) having a hydroxyl value of 50 to 100 mgKOH/g and a Tg of 50 to 100 DEG C, a cellulose resin (CR) and/or a microgel (MG), and a photoluminescent pigment, in which the ratio of the amount of the AR to the amount of the MR is 50:50 to 90:10 in terms of mass-based solid content and the ratio of the amount of the CR and/or the MG relative to the total solid content of the AR and the MR is 1.0 to 20 mass% in terms of solid content; andwherein the CC comprises an MR and an AR having a hydroxyl value of 50 to 100 mgKOH/g and a Tg of 70 to 100 DEG C, in which the ratio of the amount of the AR to the amount of the MR is 50:50 to 90:10in terms of mass-based solid content; and a coated article produced by the method.

Description

technical field [0001] The present invention relates to a method for forming a multilayer coating film and a coated article. More specifically, it relates to a method for forming a multilayer coating film and a coated article. The method for forming a multilayer coating film can be used in home appliances, office Metal materials in business machines, mobile devices, automotive supplies, etc., such as magnesium alloy, aluminum alloy, and stainless steel, etc., form a multi-layer coating film with gloss, high hardness, and excellent adhesion. Background technique [0002] As a method of coating magnesium alloy molded products, a known method is to apply an undercoat of a two-component urethane (urethane) paint containing a bright material after chemical conversion treatment, and then apply an undercoat that has already been coated. A two-component urethane paint containing a gloss material is used as an intermediate coat, and finally a UV curable resin paint is applied as a to...

AI Technical Summary

Problems solved by technology

[0007] However, this method has the following disadvantages: since the powder coating is used in the undercoating and topcoating, it is difficult to shorten the steps by including a baking step in each coating step; and, depending on the inconsistency of each baking condition The poor adhesion between the middle coat and the top coat is also worrying; moreover, since the acrylic resin powder clear paint is used as the top coat, in order to obtain the required smoothness, the primer and the top coat have to be separated. Apply to a certain degree of thick film

[0009] However, this method has the following disadvantages: since the powder coating is used in the undercoating and topcoating, it is difficult to shorten the steps by including a baking step in each coating step; and, depending on the inconsistency of each baking condition The poor adhesion between the intermediate and top coats is also a concern

However, this method has the following disadvantages: due to the use of a 2-component type on the top coat clear layer (top coat clear) (usually refers to the uppermost clear layer), it is limited by the usable time, due to the use of urethane Ester bonds form a film, so it cannot be expected to be a high-hardness coating film with a pencil hardness of 3H or more

[0012] However, this method has a disadvantage. Since the clear layer on the top coat has rubber elasticity based on urethane bonds, it cannot be expected to be a high-hardness coating film with a pencil hardness of 3H or more.

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