JPH09314039A - Plotting and coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve deposition property while maintaining the density of pigments high in an ink agent by forming a unhardened base coating film containing a crosslinking agent on the surface to be coated, plotting a picture on the unhardened base coating film by using an ink containing no crosslinking agent, applying a clear coating material thereon, and baking. SOLUTION: When a color original image is plotted on surface of a body such as a car chassis, a base coating material containing a crosslinking agent is first applied on the surface to be coated in an undercoating process. Then an ink containing no crosslinking agent is used to plot a picture on the unhardened base coating film to form a unhardened coating film with a picture. Then a clear coating material is applied on the surface of the unhardened coating film with the picture and the unhardened base coating film in an overcoating process to form a unhardened clear coating film. Then the body is heated to bake the unhardened base coating film, unhardened coating film with the picture and unhardened clear coating film at one time. In this baking process, the crosslinking agent permeated through the image crosslinks the main resin in the picture film. Thus, the resin density in the picture film is increased and the adhesion property can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing and painting method for performing design painting by drawing a color original image on the surface of an object to be drawn such as an automobile body.

[0002]

2. Description of the Related Art Recently, as a printing device for a computer,
Inkjet printers are used.
This ink jet printer discharges three primary colors of red, blue, yellow, and four colors of black from a nozzle in accordance with the color tone of each pixel of image data stored in a storage device of a computer from nozzles, and onto a printing paper. The color tone of the pixel is reproduced by attaching it in a dot shape and superimposing on a printing paper. Then, by driving the nozzles in the left-right direction and driving the printing paper in the vertical direction, image data can be drawn on the printing paper.

[0003] In a printer, an object to be coated is limited to a paper-like object. For example, if image data can be directly drawn on an automobile body or the like, even a complicated design can be mass-produced industrially. Therefore, Japanese Patent Application Laid-Open Nos. 1-110159, 1-128848, 1-133800, and the like disclose an automatic drawing apparatus capable of enlarging a color original image and directly printing it on a wall or the like. I have. According to this automatic drawing apparatus, since the four nozzle units are driven in the three-dimensional directions of the X direction, the Y direction, and the Z direction, it is possible to draw the image data while enlarging the image data on the drawing wall surface. However, it is possible to mass-produce industrially. Therefore, by using this for painting automobile outer panels, bumpers, moldings, and the like, the degree of freedom in painting designs is dramatically improved.

By the way, in the case of drawing painting on an upright surface of an automobile outer panel or the like, it is extremely important to prevent dripping of the dot-shaped ink agent attached. It is necessary to prevent dripping even if inks of up to four colors are applied. Therefore, conventionally, the film thickness of the drawing coating film is made extremely thin to prevent sagging during coating.

[0005]

In order to obtain a desired color tone by reducing the film thickness, it is necessary to increase the pigment concentration in the ink agent. However, when the concentration of the pigment with respect to the resin binder in the ink agent increases, there is a problem that the strength of the coating film decreases. Further, when applied to the coating of automobile outer panels, the drawing painting process will be inserted into the present automobile painting process. Therefore, the drawing coating process is performed between the intermediate coating process and the top coating process, and by drawing painting on the surface of the uncured base coating film, applying clear paint on the surface and baking it The film and the Kur coating film will be integrally cured.

However, as described above, when the strength of the drawing coating film is low, when the adhesion test is conducted, the drawing coating film is pulled by the tough base coating film and the clear coating film, and the cohesive failure in the drawing coating film is easy. There is a problem in that the adhesion is low and the adhesion is low. This problem can be solved by increasing the resin binder concentration in the ink agent, but due to the relative decrease in the pigment concentration, the range of color tones that can be expressed becomes narrower, and the problem that the color reproducibility of the original image is poor occurs. To do.

The present invention has been made in view of such circumstances, and an object thereof is to improve the adhesiveness while maintaining a high pigment concentration in the ink agent.

[0008]

The feature of the drawing coating method of the present invention for solving the above-mentioned problems is a coating method for forming a base coating film, a drawing coating film, and a clear coating film in order on the surface of an object to be coated, Using an undercoating step of forming a uncured base coating film by applying a base coating material containing a cross-linking agent on the surface of an object to be coated, and an ink agent containing a main resin curable by reacting with the cross-linking agent and containing no cross-linking agent An intermediate coating process that forms an uncured drawing coating film by drawing on the surface of the uncured base coating film, and a clear coating film is formed by applying a clear coating on the surface of the uncured drawing coating film and the uncured base coating film. It consists of an overcoating step, a coating step consisting of the above, and a baking step of integrally baking the uncured base coating film, the uncured drawing coating film and the uncured clear coating film by heating.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, first, an uncured base coating film is formed, and an uncured drawing coating film is formed on the surface thereof. Therefore, since the base coating film and the drawing coating film are in an uncured state, the crosslinking agent, which is a relatively low molecular weight component in the base coating film, easily penetrates into the drawing coating film. Moreover, since the film thickness of the drawing coating film is thin, the cross-linking agent easily spreads over the entire drawing coating film. When the clear paint is applied and the baking process is performed, the infiltrated crosslinking agent crosslinks with the main resin in the drawing coating film. Therefore, the resin concentration in the drawing coating film is increased and the adhesion is improved.

In order to obtain a predetermined performance as a drawing coating film, the ratio of the resin component and the pigment component in the drawing coating film needs to be within a predetermined range. The resin components are the main resin and the cross-linking agent, and it is necessary that the functional groups of the two react with each other in a one-to-one relationship. Further, since the dispersion stability of the pigment in the ink agent is governed by the main resin, if the content of the main resin is reduced, the amount of the pigment for stabilizing the dispersion also decreases, and as a result, the pigment concentration decreases. Therefore, in order to secure the absolute amount of the pigment, the amount of the main resin which is commensurate with that is required.

However, if the crosslinking agent is added to the pigment in an amount commensurate with the amount of the base resin required, the pigment concentration in the ink agent becomes relatively low, and the range of expressible color tone becomes narrow. Therefore, in the present invention, the resin component in the ink agent is only the main resin necessary for stabilizing the dispersion of the pigment, and the crosslinking agent that does not contribute to stabilizing the dispersion of the pigment is removed. As a result, the pigment concentration in the ink agent can be relatively increased while maintaining stable dispersion of the pigment, and the range of color tones that can be expressed can be expanded.

When the cross-linking agent permeates and migrates from the base coating film into the drawing coating film, the main resin in the drawing coating film reacts with the transferred cross-linking agent, so that the mechanical performance of the drawing coating film is improved. Can be secured. As the base paint, one containing a cross-linking agent and cross-linking and curing by heating is used. Acrylic / melamine resin paints, polyester
Melamine resin paints, acrylic / epoxy / melamine resin paints, polyester / epoxy / melamine resin paints, and other melamine resins as cross-linking agents, acrylic / isocyanate resin paints, polyester / isocyanate resin paints, and other polyisocyanates as cross-linking agents Paint etc. is used.

The film thickness of the drawing coating film is extremely thin, and the amount of the crosslinking agent penetrating from the base coating film into the drawing coating film may be extremely small. Therefore, the ratio of the main resin to the cross-linking agent in the resin component of the base paint may be the same as that of the conventional base paint, such as main resin / cross-linking agent = 6/4 to 10/1 when the cross-linking agent is a melamine resin. When the cross-linking agent is polyisocyanate, the amount is determined by the hydroxyl value of the main resin,
Generally, it is preferable that OH / NCO is around 1.0.

The base coating film may be an uncured coating film in which the solvent has just volatilized, or a semi-cured coating film that is partially cured by heating at low temperature for a short time. The color tone is generally white, but the color tone is not limited to this and can be variously selected according to the purpose, and the film thickness can be freely selected. As the ink agent, an agent including a main resin that is crosslinked with a crosslinking agent such as an acrylic resin, a polyester resin, or an epoxy resin to be cured, and various pigments and a solvent is used. The pigment concentration depends on the type of pigment. For example, in the case of red, blue, and yellow pigments, it is 20 with respect to the base resin.
˜70 PHR, preferably 30˜60 PHR. In the case of a black pigment, it is about 1 to 30 PHR, preferably about 5 to 20 PHR. If the pigment concentration is too low, the range of color tones that can be expressed will be narrowed, and if the pigment concentration is too high, the mechanical properties of the drawing coating film will deteriorate and the adhesion will decrease. By setting the pigment concentration as high as this range, the range of color tones that can be expressed is expanded, the color reproducibility is excellent, and the adhesion is excellent.

The thickness of the monochromatic drawing coating film is generally 1 μm or less. If the film thickness is larger than this, the problem of sagging will occur. As clear paints, conventional cross-linking curable paints such as acrylic / melamine resin paints, polyester / melamine resin paints, acrylic / isocyanate resin paints are generally used, but in some cases, solvent volatilization curable paints (lacquers) and oxidation polymerization It is also possible to use a one-part cross-linking curable coating material such as a mold. Since penetration of the cross-linking agent from the uncured clear coating film to the uncured drawing coating film is also expected, it is desirable to use a clear paint using a cross-linking agent similar to the base paint.

The clear paint provides gloss and enhances the appearance quality and protects the drawing coating film. The thickness of the clear coating film is not particularly limited, but is generally about 20 to 40 μm.

[0017]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. The following Examples 1 to 5 and Comparative Example 1
In each of No. to No. 4, each paint having the composition shown in Table 1 was used.

[0018]

[Table 1] (Example 1) In this example, a quinacridone-based red pigment is used as the organic pigment in the ink agent.

The above white base paint is diluted with a thinner to a coating viscosity, and a steel sheet coated with electrodeposition has a dry film thickness of 25 μm.
m after spray painting, then wet on w
By the et coating method, the above ink was applied by an automatic drawing coating device so that the dry film thickness was about 1 μm. Furthermore, dilute the above clear paint to the coating viscosity with thinner and we
Spray coating was performed on the surface of the drawn coating film by the ton wet coating method so that the dry film thickness was 30 μm.

After being left at room temperature for 15 minutes, it was heated at 140 ° C. for 20 minutes to integrally bake and dry the three coating films. After leaving the obtained coated plate at room temperature for 24 hours,
An adhesion test was conducted by a cross-cut tape method specified in IS-K-5400, and the initial adhesion was evaluated by counting the number of squares from which the coating film was peeled off. Also, the coated plate that has been left at room temperature for 24 hours is immersed in water at 40 ° C for 10 days, pulled up, and allowed to stand at room temperature for 24 hours.
After leaving for a period of time, the same adhesion test was performed to evaluate the water-resistant adhesion. Table 2 shows the results.

Example 2 After applying the base paint, 8
A coated plate was formed in the same manner as in Example 1 except that a preheating step of heating at 0 ° C. for 10 minutes was performed, and then the ink was applied by drawing. Then, similarly, the initial adhesiveness and the water resistant adhesiveness were evaluated, and the results are shown in Table 2. (Example 3) A coated plate was formed in the same manner as in Example 1 except that an isoindolinone-based yellow pigment was used as the organic pigment. Then, similarly, the initial adhesiveness and the water resistant adhesiveness were evaluated, and the results are shown in Table 2.

Example 4 A coated plate was formed in the same manner as in Example 1 except that a phthalocyanine-based blue pigment was used as the organic pigment. Then, similarly, the initial adhesiveness and the water resistant adhesiveness were evaluated, and the results are shown in Table 2. Example 5 A coated plate was formed in the same manner as in Example 1 except that carbon black was used as the organic pigment. Then, similarly, the initial adhesiveness and the water resistant adhesiveness were evaluated, and the results are shown in Table 2.

(Comparative Examples 1 to 4) After applying the base paint, a baking step of heating at 140 ° C. for 20 minutes was performed,
Then, Examples 1 to 5 except that the ink agent was applied by drawing.
A coated plate was formed in the same manner as in. Then, similarly, the initial adhesiveness and the water resistant adhesiveness were evaluated, and the results are shown in Table 2. The comparative example corresponding to the second embodiment is the same as the first comparative example, and thus the description thereof is omitted.

[0024]

[Table 2] (O: 0/100 △: 0/100 to 1/100 x: 1/100 or more) (Evaluation) From Table 2, although there is a difference depending on the type of the pigment of the ink agent, the base coating film was formed as in the example. It is clear that the drawing of the ink agent in the uncured state significantly improves the adhesiveness as compared with the comparative example in which the ink agent is drawn after baking the base coating film.

This is because the melamine resin, which is a relatively low molecular weight component and a cross-linking agent in the base coating film, permeates and migrates into the drawing coating film, and the acrylic resin which is the main resin in the drawing coating film during the baking process. It is thought that this is due to the reaction. Permeation and migration of melamine resin from the uncured clear coating may also occur. Further, since there is no difference between the results of Example 1 and Example 2, whether the base coating film is in a completely uncured state or in a semi-cured state of about 10 minutes baked at 80 ° C. It is considered that the strength of the drawn coating film was improved by the permeation and migration of the melamine resin, which is a cross-linking agent.

(Conventional Example) A coated plate was formed in the same manner as in Example 1 and Comparative Example 1 except that the ink composition having the conventional composition shown in Table 3 was used. Similarly, the initial adhesion and the water resistance are evaluated, and the color reproducibility is evaluated visually, and the results are shown in Table 3 together with the results of Example 1 and Comparative Example 1.

[0027]

[Table 3] It is clear that when an ink agent having a large amount of resin component is used as in the conventional example, the adhesion is excellent, but the color reproducibility is poor because the pigment concentration is low. That is, according to the drawing coating method of this embodiment, it is apparent that both color reproducibility and adhesiveness can be achieved.

[0028]

In other words, according to the drawing coating method of the present invention, the strength of the drawing coating film can be improved while keeping the pigment concentration in the ink agent high. Therefore, the range of colors that can be expressed is expanded, and high reproducibility of the color of the original image to be drawn can be ensured and high adhesion can be ensured.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Daisuke Abe, 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor, Hiroaki Kiyata, No. 1, Zuijyo, Miyoshi Town, Kamo District, Aichi Prefecture Kansai Paint Within the corporation

Claims (1)

[Claims] 1. A coating method for sequentially forming a base coating film, a drawing coating film, and a clear coating film on the surface of an object to be coated, which comprises applying a base coating material containing a crosslinking agent to the surface of the object to be coated to form an uncured base coating. An uncured drawing coating film is formed by drawing on the surface of the uncured base coating film using an undercoating step of forming a film and an ink agent containing a main resin which is curable by reacting with the crosslinking agent and containing no crosslinking agent. An intermediate coating step of forming, an overcoating step of applying a clear coating to the surface of the uncured drawing coating film and the uncured base coating film to form an uncured clear coating film, and a coating step comprising: A drawing coating method comprising: a base coating film, the uncured drawing film and the uncured clear coating film which are integrally baked.