JP2008136922A - Method for preparing painted article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing a painted article having excellent evenness of paint coat achieved by preventing sagging and unevenness of coated paint. <P>SOLUTION: The method for preparing a painted article comprises a step of applying paint onto a surface of an article to be painted under such a condition that the surface temperature thereof is kept higher than the boiling temperature of the paint. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a coated product that prevents sagging of paint and uneven coating.

The paints are classified into organic solvent paints and water paints according to the liquid medium used. Organic solvent-based paints are widely used as industrial paints because they are excellent in film quality such as adhesion to an object to be coated and film hardness, and also have good workability in the coating process.
In recent years, however, water-based paints use water as the main solvent, so they are less dangerous to workers in the paint environment than organic solvent-based paints, and prevent global warming (reducing CO ₂ emissions) and the atmosphere. It is attracting attention because it contributes to global environmental problems such as pollution prevention (reduction of volatile organic compound emissions).

Immediately after the paint is applied to the object to be coated, a phenomenon that the paint moves due to its own weight, so-called sagging of the paint, occurs, and the appearance of the finished paint may be deteriorated.
Further, the appearance of the finished coated product is also deteriorated due to uneven coating due to the wettability of the coating on the surface (hereinafter referred to as the coated surface) where the coating is applied to the object. In particular, water-based paints using water, which has a higher latent heat of vaporization (difficult to evaporate) as compared with organic solvent-based paints, are remarkable. In view of this, a coating method is disclosed in which sagging of the paint is prevented by adjusting the paint temperature (higher than the standard temperature) due to the evaporation promoting effect of the diluent solvent (Patent Document 1).
JP 2006-281165 A

  In Patent Document 1, the paint temperature is set higher than the standard paint temperature, and the evaporation of the diluting solvent is positively increased. However, when the evaporation of the diluting solvent is increased, the viscosity of the paint is increased in the coating apparatus, and in the worst case, the paint is solidified in the coating apparatus, which makes it impossible to apply the paint.

  The gist of the present invention is a method for producing a coated product in which the coating material is applied in a state where at least the surface of the coating material to be coated is at a temperature exceeding the boiling point of the coating material.

In the method for producing a coated product according to the present invention, the coating surface is applied at a temperature exceeding the boiling point of the coating material, and the evaporation of the liquid medium of the coating material starts immediately after the coating material contacts the coating surface. Since the paint solidifies, there is no time for the paint to move due to its own weight, and so-called sagging of the paint can be prevented.
In addition, by preliminarily applying the coating surface to the coating material, the wettability between the coating surface and the coating material is improved, and the coating coating becomes uniform, thereby eliminating coating unevenness.
Furthermore, by making the coated surface a parent paint and raising the temperature above the boiling point of the paint, the surface free energy of the coated surface is increased, the interfacial tension with the paint is reduced, and uneven coating is eliminated. The change in surface free energy associated with deposition can be suppressed by immediately solidifying the coating, resulting in uneven coating and a coated product with excellent coating uniformity.
In addition, we are reducing CO ₂ emissions by using water-based paints reducing (global warming) and volatile organic compound emissions (Air Pollution Control). In paints containing metal powder, by eliminating coating sagging and unevenness of coating, there are areas where the glitter is reduced due to precipitation, separation, and movement of the metal powder in the coated film. Can be prevented.

  The present invention realizes the object of suppressing sagging of the paint by positively evaporating the liquid medium of the paint applied to the object.

The material of the object to be coated is not particularly limited as long as it can be painted. Specifically, metal materials such as aluminum or its alloy, copper or its alloy, iron or its alloy, zinc or its alloy, magnesium or its alloy, titanium or its alloy, vinyl chloride, polystyrene, acrylic, polycarbonate, acrylonitrile butadiene Styrene copolymer, acrylonitrile styrene copolymer, polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polyamide, nylon, polyacetal and other thermoplastic resin materials, polystyrene, polyolefin, poly Thermoplastic elastomers such as vinyl chloride, polyurethane, polyester, and polyamide, silicone, styrene butadiene, urethane, butadiene Synthetic rubber and natural rubber such as isoprene and fluorine, thermosetting resin materials such as epoxy resin, phenol resin, cyanate resin, urea resin and guanamine resin, ceramic materials such as alumina, zirconia and ceramics, natural materials such as wood and paper, etc. Can be used.
These materials may be one kind or a mixture of two or more kinds. Furthermore, a base treatment layer may be formed on these materials by electroplating, electroless plating, painting, printing, or by precious metal plating such as nickel, chromium, or gold, painting, printing, or the like.

  The paint only needs to contain at least a resin and a liquid medium, and is not particularly limited as long as it is an organic solvent-based paint using an organic solvent as a liquid medium, or a water-based paint using a solution of water or a mixture of water and an organic solvent. . For example, it may be a clear paint containing no color material, or an enamel paint containing dyes, pigments, and metal powder as the color material.

  The method for bringing the article to be coated to a temperature exceeding the boiling point of the paint is not particularly limited as long as at least the coated surface can be heated to the boiling point of the paint or more. For example, a method in which an object to be coated is heated in an electric furnace or a baking furnace, or a method in which the coated surface is blown with a flame such as a gas burner can be used.

Further, the method of forming the parent paint of the object is not particularly limited as long as the wettability between the coated surface and the paint can be improved. For example, a coupling treatment using a coupling agent such as an organic silane compound or an organic titanium compound, a flame treatment in which an oxidation flame, a silicic oxidation flame, a titanium oxidation flame or an aluminum oxidation flame is sprayed on the coated surface, an ultraviolet irradiation treatment, a corona Discharge treatment, plasma treatment, electron beam treatment, radiation treatment, chemical treatment, physical roughening treatment, and the like can be used.
In addition, if it is a flame treatment, an ultraviolet irradiation treatment, a corona discharge treatment, a plasma treatment, an electron beam treatment, and a radiation treatment, the temperature of the coated surface can be raised by these treatments. The step can be the same as the step of bringing the article to be coated to a temperature exceeding the boiling point of the paint.

(Example 1)
A surface made of brass with an outer diameter of 10 mm and a length of 100 mm and having a circular outer cross section is buffed on the surface to which the paint is applied (applied surface) to smooth the surface and degreased with dichloromethane. Then, it was heated in an electric furnace and heated to 150 ° C., and a thermosetting acrylic paint (manufactured by Kansai Paint Co., Ltd., Magiclon 1000 black, boiling point 145 ° C.) was spray-coated while the temperature of the coated surface was 150 ° C. Subsequently, it dried on 160 degreeC and the conditions for 30 minutes, and obtained the coating material whose average film thickness is 50 micrometers.

(Example 2)
A white material made of a polycarbonate resin having an outer diameter of 10 mm and a length of 100 mm and having a circular outer cross-section is degreased with isopropyl alcohol, and the coated surface is then subjected to a gas burner (manufactured by Tsubaki Seiki Co., Ltd., BT- 20 VX) for 0.5 seconds, the coating surface temperature is 100 ° C., and the coating surface temperature is 100 ° C., then water-based acrylic paint (Musashi Paint Co., Ltd., AQ716 clear, boiling point 100 ° C.) is sprayed. Painted. Subsequently, it dried on 80 degreeC and the conditions for 60 minutes, and obtained the coating material whose average film thickness is 50 micrometers.

(Example 3)
A surface made of brass with an outer diameter of 10 mm and a length of 100 mm and having a circular outer cross section is buffed on the surface to which the paint is applied (applied surface) to smooth the surface and degreased with dichloromethane. A solution obtained by diluting silica sol (manufactured by Nissan Chemical Industries, Ltd., IPA-ST) 10-fold with isopropyl alcohol was spray-coated, and the coated surface was made a parent paint for the paint to be coated later. Next, it was heat-treated at 150 ° C. in an electric furnace and spray-coated with a thermosetting acrylic paint (manufactured by Kansai Paint Co., Ltd., Magiclone 1000 Black, boiling point 145 ° C.) with the temperature of the coated surface being 150 ° C. Then, it dried on 160 degreeC and the conditions for 30 minutes, and obtained the coating material whose average film thickness is 50 micrometers.

Example 4
A white material made of a polycarbonate resin having an outer diameter of 10 mm and a length of 100 mm and having a circular outer cross section is degreased with isopropyl alcohol, and then treated with silicic acid flame treatment (Itro treatment, Ishimat Co., Ltd.) Japan, Itoro treatment device) was applied to make the paint to be applied later a parent paint, and at the same time, the temperature of the coated surface was set to 200 ° C. Next, after applying a water-based acrylic paint (manufactured by Musashi Paint Co., Ltd., AQ716 clear, boiling point 100 ° C.) in a state where the temperature of the coated surface is 100 ° C., it is dried at 80 ° C. for 60 minutes, and averaged A coated product having a film thickness of 50 μm was obtained.

(Example 5)
A white material made of a polycarbonate resin having an outer diameter of 10 mm and a length of 100 mm and having a circular outer cross-section is degreased with isopropyl alcohol, and then subjected to an oxidization flame treatment (manufactured by Tsubaki Machine Co., Ltd., BT -20VX) to make the paint to be applied later a parent paint, and at the same time, the temperature of the coated surface was set to 200 ° C. Next, water-based silver colloidal paint (the following composition, boiling point: 100 ° C.) is spray-coated while the temperature of the coated surface is 100 ° C., and then dried under the conditions of 80 ° C. and 24 hours, and the average film thickness is 5 μm. A painted product was obtained.
<Composition of water-based silver colloid paint>
AQ20 clear (acrylic resin paint: manufactured by Musashi Paint Co., Ltd.) 10.0% by weight
84.9% by weight of water
AG70nm (silver nanoparticles: ULVAC Material Co., Ltd.) 5.0% by weight
DISPERBYK-190 (dispersing agent: manufactured by Big Chemie Japan Co., Ltd.) 0.1% by weight
The above components were dispersed in a ball mill for 24 hours to obtain a water-based silver colloid paint.

(Comparative Example 1)
In Example 1, a coated product having an average film thickness of 50 μm was obtained in the same manner as in Example 1 except that the heat treatment was not performed and the temperature of the coated surface was changed to room temperature.

(Comparative Example 2)
In Example 5, a coated product having an average film thickness of 5 μm was obtained in the same manner as in Example 5 except that the coated surface was not changed to a parent paint and the temperature of the coated surface was changed to room temperature.

<Evaluation of coating sagging and uneven coating>
Visually observed under illumination for color observation (natural daylight illumination) in accordance with JIS K 5600-4-3: 1999 “General test method for paints—Part 4: Visual characteristics of coating film—Section 3: Visual comparison of colors” The evaluation of the sagging of the paint and the unevenness of the coating were carried out.

<Evaluation of coating film uniformity>
Using an eddy current film thickness meter (manufactured by Sanko Electronic Laboratory Co., Ltd., EDY-1000), the coated surface was measured at 10 locations (10 mm intervals) in the longitudinal direction, and the difference between the minimum film thickness and the maximum film thickness The film uniformity was evaluated. In addition, the average value of the above ten measurement points was defined as “average film thickness”.

  As described above in detail, the method for producing a coated product of the present invention can prevent sagging of coating and uneven coating, and has excellent coating film uniformity.

Claims (4)

A method for producing a coated product in which the coating material is applied in a state where at least the surface of the coating material to be coated is at a temperature exceeding the boiling point of the coating material. The method for producing a coated product according to claim 1, wherein the surface to which the paint is applied is subjected to a parent paint treatment in advance. The manufacturing method of the coated material of Claim 1 or Claim 2 in which the said coating material contains water. The manufacturing method of the coated material in any one of Claim 1 thru | or 3 in which the said coating material contains metal powder.