EP-4737528-A1 - ACTIVE ENERGY RAY-CURABLE COATING COMPOSITION

Abstract

In order to reduce the light absorbed by a coated object and suppress a temperature rise of the coated object, the active energy ray-curable coating composition contains an active energy ray-curable resin and a light-reflecting agent in an amount capable of suppressing the temperature rise of the coated object. The light-reflecting agent is contained in such an amount that the amount of the temperature rise of the coated object is 1,945,000°C·lx or less, or the light-reflecting agent is contained in an amount of 29 to 75 weight percent.

Inventors

• YOSHIOKA, Youichi
• FUKUYAMA, YASUHIRO
• KOSEMURA, Tooru

Assignees

• Nissan Motor Co., Ltd.

Dates

Publication Date

20260506

Application Date

20230629

Claims (10)

1. An active energy ray-curable coating composition comprising: an active energy ray-curable resin; and a light-reflecting agent in an amount capable of suppressing a temperature rise of a coated object.
2. The active energy ray-curable coating composition according to claim 1, wherein the light-reflecting agent is contained in such an amount that an amount of the temperature rise of the coated object is 1,945,000°C·lx or less.
3. The active energy ray-curable coating composition according to claim 1 or 2, wherein the light-reflecting agent is contained in an amount of 29 to 75 weight percent.
4. The active energy ray-curable coating composition according to claim 3, wherein the active energy ray-curable resin is an amorphous resin.
5. The active energy ray-curable coating composition according to any one of claims 1 to 4, wherein the light-reflecting agent is barium sulfate and/or titanium oxide.
6. The active energy ray-curable coating composition according to any one of claims 1 to 5, wherein the light-reflecting agent has a light reflectance of 99% or more.
7. The active energy ray-curable coating composition according to any one of claims 1 to 6, wherein the light-reflecting agent has a particle diameter of greater than 0 and less than or equal to 10 µm.
8. The active energy ray-curable coating composition according to any one of claims 1 to 7, wherein a ratio of solid contents including the active energy ray-curable resin and the light-reflecting agent is 90 weight percent or less.
9. A method of coating an automobile body, comprising applying the active energy ray-curable coating composition according to any one of claims 1 to 8 to an outer panel of the automobile body.
10. The method of coating an automobile body according to claim 9, wherein the active energy ray-curable coating composition is applied to a film thickness of 10 to 500 µm and then cured by irradiating with active energy rays.

Description

Technical Field The present invention relates to an active energy ray-curable coating composition. Background Art A known photocurable coating composition contains a photocurable resin, a photopolymerization initiator, and an extender pigment such as precipitated barium sulfate (Patent Document 1). The extender pigment is used in an amount ranging from 1 to 30 parts by weight per 100 parts by weight of the photocurable resin. Prior Art Documents Patent Documents Patent Document 1: JP2005-246299A Summary of Invention Problems to be solved by Invention When an automobile is left in the blazing sun in midsummer, the temperature inside the automobile may reach around 50°C, and it is therefore desirable for a coating film formed on the exterior panels or the like of the automobile body to reduce the amount of light absorbed by the exterior panels and suppress the temperature rise of the exterior panels. In this specification, such a function of the coating film is referred to as a "temperature-reducing effect." Unfortunately, testing of the above conventional photocurable coating compositions has revealed that they have almost no temperature-reducing effect. A problem to be solved by the present invention is to provide an active energy ray-curable coating composition that can reduce the amount of light absorbed by a coated object and suppress the temperature rise of the coated object. Means for solving Problems The present invention solves the above problem by including an active energy ray-curable resin and a light-reflecting agent in an amount capable of suppressing a temperature rise of a coated object. Effect of Invention According to the present invention, it is possible to reduce the amount of light absorbed by a coated object and suppress the temperature rise of the coated object. Brief Description of Drawings [FIG. 1] FIG. 1 is a cross-sectional view illustrating an example of a multilayer coating film using the active energy ray-curable coating composition according to the present invention.[FIG.2A ] FIG. 2A is a side view illustrating a method for testing the temperature-reducing effect of a coating film using the active energy ray-curable coating composition according to the present invention.[FIG. 2B] FIG. 2B is a plan view illustrating a method for testing the temperature-reducing effect of a coating film using the active energy ray-curable coating composition according to the present invention.[FIG. 3] FIG. 3 is a graph illustrating the relationship between the content of a light-reflecting agent and the amount of temperature rise. Mode(s) for carrying out Invention «Active Energy Ray-Curable Coating Composition» An active energy ray-curable coating composition according to an embodiment of the present invention is configured to include an active energy ray-curable resin, a light-reflecting agent in an amount capable of suppressing a temperature rise of the coated object, and a solvent, and, if necessary, a colorant as well as known coating additives (e.g., antifoaming agents such as silicone oil, fluorine-based surfactants, silicone-based surfactants, leveling agents such as acrylic copolymers, thickeners, viscosity reducers, etc.). It is intended that the active energy rays in this specification include light such as ultraviolet rays and electron rays. The active energy ray-curable resin compositions of the present embodiment include ultraviolet-curable resin compositions and electron ray-curable resin compositions. The ultraviolet-curable resin compositions include ultraviolet radical-curable resin compositions, such as epoxy acrylate resins, urethane acrylate resins, thermosetting acrylic resins, and thermosetting polyester resins, and cation-curable resin compositions represented by ultraviolet-curable epoxy resins. The ultraviolet rays have a lower curing energy than that of electron rays, so the ultraviolet-curable resin compositions may be used in conjunction with photopolymerization initiators. In contrast, the electron ray-curable resin compositions can use the same materials as those of the above-described ultraviolet-curable resin compositions, and the polymerization initiator can be omitted because the electron rays have a high curing energy. The active energy ray-curable resin of the present embodiment for use can be either a crystalline or amorphous resin. Note, however, that when the content of the light-reflecting agent is increased, it is preferred to use an amorphous resin. This is because the light-reflecting agent is believed to be mixed into the amorphous moiety. Examples of amorphous active energy ray-curable resins include acrylic resins represented by polymethyl methacrylate resin. The light-reflecting agent of the present embodiment has a property of reflecting sunlight, including infrared rays, and, although not particularly limited to, preferably has a light reflectance of 99% or more. Examples of light-reflecting agents of the present embodiment include barium sulfate,