JP3368434B2 - Powder application method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating powder on an article to be coated. The powder in the present invention means a powder material having any shape, including a rhenpen-like material, and the material thereof is not limited.

[0002]

2. Description of the Related Art Heretofore, powders applied as an adhesive or as a coating have been used by changing the average particle size depending on the purpose. For example, the concept of using powder with a large particle size when thick coating is required and using powder with a small particle size when thin coating has been common in the art.

[0003]

However, when powder having a large particle size is used, leveling after heating is poor, and when it is thermosetting, it is called orange peel, which is called yuzunoha. There was a problem that the finished surface of the shape remained as it was and the cosmetic appearance was lost.

On the other hand, when powder having a small particle size is used, leveling is good, but since the ratio of the surface area to the weight per particle constituting the powder is large, the bulk density is low and the carrying capacity is lowered. Further, when sprayed, it is difficult to maintain the straightness due to resistance in the air for a long time, and the intrusion of the powder is poor in the object to be coated having a shape such as a recess or a part which is narrowed in the back. Therefore, it is necessary to increase the pressure of the ejector air and increase the discharge amount of the powder in order to improve the ability of the powder to enter the recesses and the narrowed part at the back. As a result, the air flow rate also increased, and the coating efficiency was extremely low. Further, powders having a small particle size tend to be shunned in the market because they have high manufacturing costs and increase running costs even if their goodness is known.

The present invention has been made in view of the above-mentioned problems. A high-quality coating film having good leveling, excellent cosmetic properties, and good powder advancing efficiency and good coating efficiency can be obtained. It is an object to provide a powder coating method.

[0006]

In order to solve the above-mentioned problems, the present invention employs the following powder coating method. (1) A method of separately applying powders of A and B to an object to be coated, wherein powder of A having an average particle size of 15 μm or more and less than 120 μm is first applied, and then the powder of A By coating the powder of B having an average particle size smaller than the powder of 0.1 micron or more and less than 15 microns, the powder of A having a large particle size can ensure straightness and improve the coating efficiency. The powder was coated at a higher level, and the powder of B having a smaller particle diameter was used to compensate the leveling, whereby a powder coating method for obtaining a high quality coating film was obtained. (2) In the powder coating method of (1) above, the powder of A is coated and melted by temporary heating, and then the powder of B is coated and then melted or cured by heating. Was applied. (3) In the powder coating method of (1) above, A and B are used.
Each of the powders was a coating method in which the same resin was the main component. (4) In the coating method of powder according to the above (1), the powder volume volume ratio per unit area after coating or melting the powder of A and the powder of B is such that the powder of A is the powder of B. The method of applying powder was 1.1 times or more of the body. (5) In the powder coating method of (1) above, first, A
This is a method of applying a powder in which the application of the powder of No. 1 and the application of the powder of B are repeated several times.

[0007]

According to the above-mentioned method of the present invention, the coating rate can be increased and the coating thickness can be increased by first applying the powder having a large average particle size. Leveling can be supplemented with a small powder.

[0008]

EXAMPLES Examples will be specifically described below with reference to the drawings. FIG. 1 is a view showing a coating state of a powder according to the present invention. In the figure, reference numeral 1 indicates an object to be coated, and the surface of the object to be coated 1 is first coated with a powder 2 having a large particle diameter, and then, 3 shows a state in which the powder 3 having a small particle size is applied to the. As a result, the coating rate can be increased by increasing the coating rate with the powder 2 having a large particle size, and the leveling can be supplemented by the powder 3 having a small particle size to be applied next. Therefore, the surface finish can be improved and the added value can be increased even for the purpose of serious prevention. In addition, in the case of an object to be coated that has a shape such as a recess or a part that becomes narrower in the back, for example, an object to be coated such as steel furniture, a large grain is found in the shape of the recess or the part that becomes narrower in the back. Since the powder with a small diameter arrives in a direction, the rust prevention effect is enhanced, and the outer surface where aesthetics are required, the powder with a small particle size mainly covers the coating surface, so a clean finished surface. Is obtained. The situation is shown in FIG. In the figure, reference numeral 1 indicates an article to be coated, in which a depression 5 is formed, the powder 2 having a large particle size is first applied, and then the powder 3 having a small particle size is applied. It shows a state of applying.

[0009] Generally, since the cost of the powder coating material can be reduced as the amount of the extender pigment is large, a powder having a relatively large particle size and containing a large amount of the extender pigment is applied to the lower layer side of the object to be coated. By applying a powder containing a large amount of a color pigment having a relatively small particle size or a clear powder containing only a resin to the upper layer, the running cost can be reduced and the added value can be increased.

Further, in the PCM method in which post-processing is performed (coating is performed in advance before bending of a steel plate etc.), cracks may occur in the case of a tough and thick coating film, so the lower layer side A relatively thick coating made of powder with excellent workability and adhesion, the upper layer is tough and made of chemical resistance,
It is also possible to form a relatively thin coating film by using a powder of a material in consideration of weather resistance and the like.

[0011] In recent years, coatings having a good design such as matte, suede tone and hammer tone type have been favored in the market, but according to the method of the present invention, beads such as urethane, polystyrene or glass are required. By applying a colored material or a powder having a relatively small particle size mainly composed of those components to the upper layer, a matte or suede-like coating film can be easily obtained, and a resin having poor compatibility or By dispersing the powder having a relatively small particle size to which the components are added in the upper layer portion, a hammertone type coating film can be easily obtained. Also, when they are changed to different powders, they often remain in the flow path of the powder, causing quality problems, but by providing the flow path independently according to the method of the present invention, It does not cause such a problem.

Further, a powder having a high molecular weight and a large particle size is
In addition to poor leveling at the time of heating and melting, air existing around the particles further hinders leveling, and when the surface melts quickly, the air existing around the particles remains as bubbles. As a way to solve such problems,
In the present invention, after applying a powder having a large particle size, the powder is melted by temporary heating, and then a powder having a small particle size is applied to cover a pinhole or a thin portion of the coating film, It is possible to obtain a high-quality coating film that is free from defects and has good leveling. The situation is shown in FIG. In the figure, reference numeral 1 indicates an object to be coated. First, a powder having a large particle size is first applied to the object to be coated 1, and a powder 3 having a small particle size is applied onto a coating film 6 in a molten state by temporary heating. It shows the state of application.

The type of powder in the lower layer and the upper layer is not particularly limited, but organic powder is preferable in the lower layer from the viewpoint of adhesion, and a mixture of inorganic and organic powders or It may be an inorganic material surrounded by an organic capsule.
In particular, since fluorine-based powders and polyimide-based powders, which can have high added value, are expensive, the present invention can suppress running costs and exhibit high performance.
Further, in the case of thermosetting, compatibility may be poor due to a difference in catalyst, curing agent, functional group, or the like, and a repelling phenomenon may occur. Therefore, it is desirable to use the same resin system.

Furthermore, since the leveling phenomenon largely depends on the surface tension when each powder material is melted, the surface tension when the powder is melted is preferably 40 dyne / cm or more. Also, as mentioned above, from the economical and productivity perspectives,
The advantage can be exhibited by increasing the amount of the lower layer by using a large amount of powder having a large particle size. Also, by coating a large particle size powder made of a resin having a functional group and a small particle size powder made of a curing agent in order, the coating film performance can be improved without worrying about the pot life of the coating film. Can be improved.
For example, heating and melting or crosslinking after repeating coating and dispersion coating multiple times with a large particle size powder that has an isocyanate functional group in polyester and a small particle size powder that encapsulates blocked isocyanate By this, the purpose can be achieved.

[0015]

According to the present invention, since the powder coating method as described above is used, the leveling is good and the cosmetic appearance is excellent.
It is possible to obtain a high-quality coating film while ensuring the linearity of the powder and also having good coating efficiency.

[Brief description of drawings]

FIG. 1 is a view showing a coating state of powder according to the present invention.

FIG. 2 is a diagram showing a state in which powder is applied according to the present invention to an object to be coated having a hollow portion.

FIG. 3 is a diagram showing another embodiment of a powder coating state according to the present invention.

[Explanation of symbols]

1 Object to be coated 2 Powder with large particle size 3 Powder with small particle size 5 Recessed portion 6 Film in molten state

Claims (5)

(57) [Claims] 1. A method of separately applying powders of A and B to an object to be coated, wherein powder of A having an average particle size of 15 μm or more and less than 120 μm is first applied, and then the powder is applied. A
By applying a powder of B having an average particle size smaller than the powder of 0.1 to 0.1 μm and less than 15 μm.
A straight particle is ensured by the powder of A with a large particle size, and the transfer efficiency is improved.
The powder of B having a small particle size is applied as a level.
A powder coating method, characterized in that a high quality coating film is obtained by supplementing the ring . 2. A powder of A is applied and melted by temporary heating.
Then, after applying the powder of B, by heating
The powder coating method according to claim 1, wherein the powder coating is performed by melting or curing . 3. The powders A and B each contain the same resin as a main component.
Powder method of coating according to claim 1, characterized in that a. 4. After coating or melting the powder of A and the powder of B
Of the coating film thickness volume ratio per unit area of A, the powder of A is the powder of B
It is 1.1 times or more of the above . 5. A powder of A is applied first, and then a powder of B is applied.
The powder coating method according to claim 1, wherein the coating is repeated a plurality of times .