JPS63236568A - Metallic finish-coating - Google Patents

Abstract

PURPOSE:To permit a coating with superior quality capable of concealing a foundation coat by applying the second paint containing pulverized metallic pigment which is less capable of concealing the first paint with high concealing properties and is below a specific value on the surface of the first paint using 'wet-on-wet technique'. CONSTITUTION:A metallic finish-coating method is composed of the first coating process, the second coating process and a drying process. In the first coating process, the first paint is applied on the surface of an object to be coated so that the concealing rate stands at 60% of more. In the second coating process, the second paint containing metallic powder with a concealing capability of 10,000cm<2>/g or less, e.g. pulverized aluminium, copper and mica, is applied on the surface of the first coating using 'wet-on-wet technique'. In this case, the concealing rate of the second paint should be within the range of 5-40% which allows no adverse effect of membrane physical property. As a result, even paints with inferior concealing capability can be used to make desired coating colors available easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a metallic paint finishing method, and more particularly to a metallic paint finishing method that provides 1q of bright, bright metallic finishes.

Is the metallic paint finishing method of the present invention applied to cars and houses? l!
Useful for painting the surfaces of products, etc.

[Conventional Technique vr4] Conventionally, surfaces of automobiles, home appliances, etc. have been painted with a metallic paint finish using a metallic paint containing a metal powder pigment such as aluminum powder. To achieve this metallic finish, generally a metallic paint is applied first, a clear paint is applied wet-on-wet, and then the two coats are baked to dry and cured as one. The first method is used. or,
There is also a metallic paint finishing method in which only the metallic paint is applied and dried, using a one-coat one-bake method.

In addition, in order to perform a metallic paint finish on the production line, metallic paint tends to cause metallic unevenness when applied once, so in order to achieve a uniform finish, two paint guns are used to apply the same paint in two stages. There are many.

[Problems to be Solved by the Invention] In recent years, metallic paint finishes with high brightness have been preferred from the viewpoint of design. As metal powder pigments contained in such high-brightness metallic paints, those having uniform particle sizes are known, for example, as disclosed in Japanese Patent Application Laid-Open No. 54-36607. However, it is known that such metal powder pigments generally have poor hiding properties.

Therefore, when a metallic paint using such a metal powder pigment is applied to an object to be coated, the color of the base is exposed and the desired coating color cannot be obtained in many cases.

In addition, the ultraviolet rays may penetrate to the base, deteriorating the base and causing problems such as local peeling.

To solve this problem, there is a method of applying a thick coat of metallic paint to hide the base, or of increasing the brightness of the metal powder pigment contained.

However, when applying a thick coat, it is necessary to apply the coat in multiple parts because sagging will occur if the coat is applied thickly all at once, and the process has to be changed. In addition, if the metal powder pigment is applied thickly, the orientation of the metal powder pigment will be poor, and the desired color may be lost and the gloss may be reduced.Also, in the method of increasing the content of the metal powder pigment, Since high-brightness aluminum powder is generally expensive, there is a problem in that the cost increases.Furthermore, there is also a problem in that interlayer adhesion with the clear layer decreases in two-coat, one-bake coating.

Note that if a paint of a similar color to the final paint color is used as the base, even if the hiding power of the metallic paint is inferior, it will not be much of a problem. However, on a production line, products come in a variety of paint colors, and changing the base color for each color complicates the process and poses problems in workability.

The present invention was made in view of these circumstances, and
To provide a metallic coating finishing method that has excellent hiding properties for the base, does not adversely affect cost, finishing properties, coating film performance, etc., and can be easily applied to current coating processes.

[Means for Solving the Problems] The metallic coating finishing method of the present invention includes a first coating step of coating the surface of the object to be coated with a first coating material with a concealment rate of 60% or more to form a first coating film. , concealing power is 10000cmt/c
The second paint containing metal powder pigment of J or less has a hiding rate of 5.
A second coating step in which a second coating film is formed by applying wet-on-wet to the surface of the first coating film so that the coating thickness is ~40%, and integrally drying the first coating film and the second coating film. It is characterized by a drying process and a drying process.

The metallic coating finishing method of the present invention includes a first coating step, a second coating step, and a drying step.

The first coating step is a step in which the first coating material is applied to the surface of the object to be coated with a concealment rate of 60% or more. Here, the concealment rate is J rsK
5400.

If the hiding rate of the first paint is lower than 60%, the hiding ability will be poor and the base will become visible, making it impossible to obtain the desired effect.

This first coating step can be performed by a conventionally known coating method such as air spray, electrostatic coating, roll coater, or flow coater.

The second coating process is a process of wet-on-wet coating of the second coating material on the surface of the first coating film applied by the first coating process.

This second tJ material contains a metal powder pigment having a hiding power of 10,000 cm2/g or less. Aluminum powder is generally used as the metal powder pigment, but copper powder, mica powder, etc. may also be used.

If the hiding rate of the second paint is lower than 5%, the rate at which the color of the first coating film will show through becomes high, and the desired paint color may not be obtained. This is not possible and may adversely affect the physical properties of the coating film.

The metal powder pigment contained in the second paint has a hiding power of 100%.
00cm2/Q or less is used.

If a coating having a hiding power higher than 10,000 cm'/g is used, the high brightness of the resulting coating film will be reduced and the desired finish will not be achieved.

Note that the hiding power referred to herein is a value measured by a method such as a light transmission method, and is a value specific to metal powder pigments.

For example, in the case of aluminum powder, [Alpaste 779ONJ (Toyo Aluminum Co., Ltd.)!J41
) has a concealing power of 18. -000 cm2/g, and the hiding power of "Alpaste Mila Glow 1000" (Toyo Aluminum Co., Ltd. I'j) is 4.000 cm2/Q. In the case of a pigment whose hiding power is unknown, it can be easily determined by proportional calculation by preparing a paint containing a certain amount of the pigment and comparing the hiding rate with a paint using a pigment whose hiding power is known. Can be done.

The content m of the metal powder pigment contained in the second paint is preferably in the range of 3 to 15 parts by weight per 100 parts by weight of the resin solid content of the second paint. Within this range, a coating film that is particularly excellent in high brightness and excellent in various physical properties can be obtained.

In this second paint, various organic pigments can be used in addition to the metal powder pigment. Note that in order to maintain the characteristics of the metal powder pigment and maintain high tS brightness, it is desirable to use a highly transparent organic pigment.

This second coating step can be performed using the same coating means as the first coating step. If air spray painting or electrostatic painting is used, a particularly excellent coating film with high brightness can be obtained.

The second coating step is performed by applying the second coating material to the surface of the first coating film in a wet-on-wet manner.

The time interval between the first coating step and the second coating step is not particularly limited. Conventional 2-stage f! ! If it is performed at the same intervals as i-painting, it can be applied to conventional production lines as is.

Note that the first paint is not particularly limited as long as its hiding power is greater than or equal to the hiding power of the second paint. For example, it can be a solid color similar to the second paint. Also, the concealment power is 1
It is also preferable to contain a metal powder pigment of 0,000 cm2/g or more. Since such a metal powder pigment has excellent hiding power, it is possible to maintain a high hiding power of the first coating material. If the same type of metal powder pigment as the second paint is used, the hues of the first paint and the second paint can be approximated, making it easier to determine the color of the second paint.

The first coating layer applied in the first step and the second coating film applied in the second step are integrally dried in a drying step.

These drying conditions are the drying conditions of the resin components that make up each paint,
Various settings can be made based on the curing conditions.

In addition, before the drying process, wet 1 to -on-wet 2nd
A clear coating process may also be performed in which a clear paint is applied to the surface of the coating film.

[Operations and Effects of the Invention] In the metallic paint finishing method of the present invention, a first paint having a high hiding power is applied before applying a second paint having a low hiding power, and the first paint formed by the first paint is coated with a first paint having a high hiding power. A second paint is applied to the surface of the coating film. Therefore, the F background can be easily hidden due to the hiding property of the first paint. At this time, if the first paint and the second paint are of similar color tone, the color of the second paint can be easily determined regardless of the color tone of the base.

Further, the metallic coating finishing method of the present invention can be applied as is to the two-step coating that is normally performed in conventional metallic coating on a production line. For example, in the first step, the first paint is applied first, and in the second step, the second paint is applied wet-on-wet. This allows the present invention to be applied to conventional processes as is.

Therefore, according to the metallic paint finishing method of the present invention, it is now possible to use pigments that were previously difficult to use due to their low hiding power, and it is now possible to create paint colors that were previously difficult to use. can.

Furthermore, there is no need to pre-apply an undercoat paint that matches the color tone of the metallic paint, and the base coat can be the same for each paint color, making it possible to shorten the process.

[Example] This will be explained in detail below using examples.

(Example 1) (First coating step) Acrylic resin (Acrydic 47-712J, manufactured by Dainippon Ink & Chemicals Co., Ltd.) 104 heavy foot part and melamine tree! 11 (r Super Beckamin J-820-60J
, manufactured by Dainippon Ink & Chemicals Co., Ltd.) as a binder, and aluminum powder (r716ON, manufactured by Toyo Aluminum Co., Ltd.) with a hiding power of 16°000 cm1/l; J was added to the total solid content. A first paint of silver metallic color containing 13% by weight was prepared. The hiding rate of this first paint is 80% when the wet film thickness is 8 μm.

In addition, a second paint of silver metallic color was prepared, which contained 13% by weight of aluminum powder (r762ONsJ, manufactured by Toyo Aluminum Co., Ltd.) in the total solid content in the same resin 4N as the first paint. The aluminum powder used was a high brightness aluminum powder having a hiding power of 8.000 cm2/9. The hiding rate of this second paint was 30% when the wet film thickness was 8 μm.

(1) First coating process The first paint was adjusted to a viscosity of 14 seconds (Ford Kupki W/1.20°C) using a 1=1 mixed solvent of ethyl acetate and 1-luene, and then air sprayed. (1) The coating was applied to a coated and water-polished test plate to give a dry film thickness of 8 μm.

(2) Second coating step: The second coating material was similarly adjusted to have a viscosity of 14 seconds, and 30 seconds after application of the first coating material, it was coated on the surface of the first coating film to a dry film thickness of 18 μm.

(3) Clear painting process Acrylic resin ([Acridic 44-179J, manufactured by Dainippon Ink & Chemicals Co., Ltd.) 112-layered resin and 40-layered melamine resin similar to the first paint are mixed and absorb ultraviolet rays. The clear paint was prepared by adding agents, organic solvents, etc. This clear paint was diluted with Tsurupetz 100 (manufactured by Etsuso Kagaku Co., Ltd.) to a coating viscosity of 23 seconds, and wet-
It was coated on the surface of the second coating film in an on-wet manner so that the dry film thickness was 30 μm. Note that a flash time of 5 minutes is provided between the second coating process and the clear coating process.

(4) Drying process, ]2i,c! First coating film, second coating g! The clear coating was allowed to set for 10 minutes, and then
Baked for 30 minutes at /lo°C.

(Comparative Example 1) The second paint contains 20% by weight of the same high-brightness aluminum powder as in Example 1, and has a hiding rate of 16μ and 100% by weight.
A silver metallic coating film was formed in the same manner as in Example 1 except that the first coating step was not performed. The thickness of the metallic coating is 16 μm.
The thickness of the clear coating film was 30 μm, which was the same as in Example 1.

(Example 2) Red pigment ([Shinkasha Red RF75
Carbon black (rFW-200J Te'
1 mIS in Fr total solids!
A red paint containing 1% was used, and the second paint was a high-brightness aluminum powder (with a hiding power of 4°000cm'/Q).
A red metallic paint containing a little less than 1% by weight of Milagrow 1000.1 (Toyo Aluminum Co., Ltd.) in total solids and 14% by weight of a red pigment (Berylene Maroon R-6434J, manufactured by Bayerne 1) in total solids. (30% at a hiding rate of 8μ) was applied and dried in the same manner as in Example 1 to form a red metallic coating.

(Comparative Example 2) 1st t! ! A red metallic coating film was formed in the same manner as in Example 2 except that the cloth process was not performed and the film thickness of the second coating material was 16 μm.

(Example 3) Green pigment ([Monastral Green 6Y
J, made by IC1) in the total solid content and titanium oxide ([Tie Bake CR-90J, made by Ishihara! J, Co., Ltd.
Contains 20@ffi% of the total solid content, and has a hiding rate of 15
Using 75% μ green paint, the second paint is aluminum powder (r762ONS, manufactured by Toyo Aluminum Co., Ltd.)
Contains 14% double in the total solid content and 8 if ffi% of the same green pigment as above in the total solid content, hiding rate 15
A green metallic coating film was formed by coating and drying in the same manner as in Example 1, except that 8-color metallic paints with μ of 30% were used, no clear paint was used, and the film thickness was 15 μm.

(Comparative Example 3) A green metallic strip was formed in the same manner as in Example 3, except that the first coating step 5 was not performed and the second coating film thickness was 30 μm.

(Evaluation) Using each of the obtained coated plates, hiding properties, gloss, water resistance, and scratch resistance were investigated. The results are shown in the table. The hiding power was determined by visually comparing the clarity and brightness of each coated plate.

In addition, the gloss of the coated surface was similarly determined visually. Water resistance was determined by immersing the sample in warm water at 40° C. for 20 days, and visually determining whether there were any abnormalities. Weather resistance is Satsushi 1? Accelerated weather resistance was investigated using an in-weather-o-meter for 2000 hours, and the presence or absence of abnormalities was determined visually.

(The following is a blank space.) It is clear from the table that the coated plates of each Example are superior in performance per second compared to the coated plates of each Comparative Example. For example, in Comparative Example 1, since the second paint contains a large amount of aluminum powder, the hiding power and weather resistance are poor, but there are problems in water resistance, cost, etc. Furthermore, in Comparative Examples 2.3, the hiding properties were poor even when the second paint was applied thickly. On the other hand, in the examples, the film thickness of the second coating material and the content of aluminum powder are set within a range that provides good coating film performance, and the hiding property is excellent.

Claims (4)

[Claims] (1) A first coating step in which a first paint is applied to the surface of the object to be coated with a hiding rate of 60% or more to form a first coating film, and a metal powder pigment with a hiding power of 10,000 cm^2/g or less is included. a second coating step of forming a second coating film by applying the second coating film wet-on-wet to the surface of the first coating film so that the hiding rate is 5 to 40%; A method for finishing metallic paint, comprising: a drying step of drying the second coating film integrally with the second coating film. (2) The first paint contains a metal powder pigment with a hiding power of 10,000 cm^2/g or more.
Metallic paint finishing method described in section. (3) The metallic paint finishing method according to claim 1, wherein the first paint and the second paint have similar colors. (4) Wet-on-wet second coating after the second coating process.
The metallic coating finishing method according to claim 1, which comprises performing a clear coating step of applying a clear coating onto the surface of the coating film.