JP3109385B2 - Composition method of color clear coating film having chipping resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides a chromium-plated member having a brilliant color other than chrome on its appearance.
The present invention relates to a technique for forming a color clear coating film capable of imparting impact peeling resistance (chipping resistance), and has a high practical effect when applied to exterior parts for vehicles which are easily subjected to external impact.

[0002]

2. Description of the Related Art For example, exterior members for vehicles are often formed of a synthetic resin material and plated with chrome. In addition, there are many chances that pebbles, sand particles, and the like come in and collide as usage conditions specific to vehicle exterior components. For this reason, chipping resistance that does not cause peeling while resisting an external impact is required. Increasing the plating thickness improves chipping resistance, but if you try to increase the plating thickness,
Since the plating cost increases more than in proportion to the thickness dimension, it is desired to provide some protective layer on the chromium plating. Sputtering is known as a technique for improving chipping resistance. However, there is a disadvantage that the sputtered film is corroded from the chipped portion, discoloration and peeling proceed, and molding → undercoat → drying There is a problem that the processing cost is high because the number of processes such as → sputter processing → top coat → drying is large and special equipment is required.

[0003]

Color clear coating is known as a surface treatment of a chromium plating surface. This color clear coating is a process of forming a colored transparent coating and giving a brilliant color other than chrome color, but the conventional color clear coating has low impact strength, and it is important to improve chipping resistance. No satisfactory effect was obtained. The present invention has been made in view of the above circumstances, and a method of forming a color clear coating film capable of improving chipping resistance without losing the original effect of a color clear coating film that gives a brilliant color other than chrome. The purpose is to provide.

[0004]

SUMMARY OF THE INVENTION In order to improve the chipping resistance of a color clear coating film, even if the thickness of the coating film is increased, the chipping resistance is not improved. The reason for this is that, when the thickness of the coating film is increased, cohesive failure occurs at a location where a local impact is applied, and interface separation occurs between the plating layer and the coating film. Further, even if a paint that forms a coating film having high mechanical strength is sought, it is difficult to put it to practical use because there is no one that has compatibility with the chromium surface. Then, the present inventor (A) paint that forms a coating film having high chipping resistance, and (B) the paint,
The coating conditions that can be made compatible with the chrome-plated surface,
The four conditions described above were comprehensively studied: (c) the upper limit of the film thickness dimension that does not induce interfacial peeling due to cohesive failure, and (iv) the lower limit of the film thickness dimension that can exhibit chipping resistance.
Since these four properties are interrelated, the combinations are very diverse. For example, if the type of paint in item (a) changes, the coating conditions in item (b) change, and (c),
The dimension limit of item (d) also changes. It is not enough even if we have time to try these one by one without any plan, and it requires a large amount of research expenses, and it takes a lot of effort and little effect. The present inventors have scientifically analyzed the accumulation of many years of empirical knowledge on surface treatment, selected paints with high expectation of practical effects, narrowed the scope of trial and error, and promoted test research efficiently. As a result, the method according to the present invention has been reached. In other words, the method of forming the coating film is a method of forming a color clear coating film that gives a brilliant color other than the chrome plating color to the chrome-plated member and that provides chipping resistance to withstand external impact, a. Washing the chrome-plated surface with water; b. Drying so that no water droplets remain on the washed chrome-plated surface; c. Dried chromium plating surface is slimy 40 dynes /
means to protect the cleanliness of the chrome-plated surface so as to maintain cm; d. Silicon / acrylic 2 on clean chrome plated surface
Forming a clear coating film having a thickness of 15 to 25 μm with a liquid-reactive paint, and mixing a transparent pigment in advance into the silicone-acrylic two-liquid reactive paint. Then, the clear coating film is characterized as a color clear coating film. However,
Means for protecting the cleanliness of the above item c is that the chrome-plated surface is not stained between the drying of the item b and the coating of the item d. No need. For example, if coating is performed immediately after drying, "no opportunity to be soiled" is a means of protection in this case. Further, the condition in the item b that the drying is performed so that no trace of water droplets remains is an expression of cleanliness in washing and drying. That is, in this case, the water droplet mark is an evaporation residue of the clean water, and the presence of the water droplet mark that can be visually recognized indicates impure clean water or dust in a dry atmosphere. In order for the present invention to achieve its intended purpose, it is necessary to have a degree of cleanliness that does not cause water droplets to be noticeable to the naked eye. This water droplet mark mainly indicates the absence of minute foreign matter, and the wetting property described in the section c is as follows:
It indicates the degree of chemical fouling, such as oil or oxide film, which cannot be visually identified.

[0005]

According to the above-mentioned method, the cleanliness represented by the items a to c, that is, leaving no trace of water droplets that can be visually recognized,
By ensuring a wetting property of 40 dynes / cm, the silicone-acrylic two-component reactive coating material forms a coating film with affinity for the chromium plating surface. When the coating thickness is 15 μm or less, the chipping resistance is insufficient, and when the coating thickness is 25 μm or more, there is a possibility that interfacial peeling may occur due to cohesive failure, but as in the present invention, if the film thickness is 15 to 25 μm. In this case, sufficient chipping resistance can be obtained without fear of interface separation. In addition, since the silicone-acrylic two-component reactive paint is colorless and transparent, a desired color can be added by mixing a transparent pigment with the paint (for example, a metallic luster with a bluish tint or a yellowish tint). Metal luster, etc.), and achieves both mechanical durability and a design gloss color tone, thereby increasing the commercial value. Moreover, the equipment cost and the running cost are lower than, for example, the sputtering process.

[0006]

FIG. 1 is a schematic flow chart showing one embodiment of a method for forming a color clear coating film having chipping resistance according to the present invention, wherein (A) shows a washing step, and (B) shows a washing step.
The drawing shows the drying step, (C) shows the protection step, and (D) shows the painting step. However, since it is schematically illustrated, the state of implementation of the method of the present invention is not necessarily illustrated in a realistic manner. (A) As shown in the figure, a base member 1 made of ABS (acrylonitrile / butadiene / styrene resin)
Has a chrome plating 2 formed thereon. The surface of the chrome plating 2 is cleaned with pure water 4 jetted from a nozzle 3. Pure water in this case is pure water as the opposite of an aqueous solution, not pure water in high purity chemistry. Further, the faucet is drawn for easy understanding at first glance, and is not a realistic drawing of the embodiment. (B) As shown in the figure, the surface of the chromium plating 2 washed with water is dried by warm air blown out from the blower 5.
This is also schematically drawn for easy understanding at a glance, and in short, it may be dried in a clean state.
(C) As shown in the figure, the cleanliness of the surface of the chrome plating 2 is maintained by the protection means 7. It is not always necessary to cover with a cover as shown in the figure, and the entire workplace may be a dust-free room. In this way, the wetting property of the surface of the chrome plating 2 is maintained at 40 dynes / cm or more. (D) As shown in the figure, a transparent pigment 10 is mixed with a coating resin (varnish) of a silicone-acrylic two-pack reactive paint 9 to adjust the color to a desired color, and this is applied to the chrome-plated surface 2 by a spray gun 8. Painted, 15-
A 25 μm color clear coating film 11 is formed. This diagram is also schematically drawn for easy understanding at a glance,
Painting does not necessarily have to be performed with a spray gun.
(A) to (C) Since the surface of the chromium plating 2 is kept clean as shown in FIGS.
The liquid reaction type paint 9 has a good affinity (chemical adhesion) to the chrome plating 2 and a clear coating film thickness of 1
Since it is 5 μm or more, it has sufficient chipping resistance, and since the coating film thickness is 25 μm or less, there is no danger of interfacial peeling due to cohesive failure, and the durability is excellent. The silicone-acrylic two-component reactive paint 9 of this embodiment is a paint containing an acrylic resin as a main component and a compound containing an alkoxylated silanol group as a curing agent.

[0007]

When the present invention is applied, the cleanliness represented by the items a to c, that is, leaving no trace of water droplets that can be discerned by the naked eye, and securing a dribble property of 40 dynes / cm, is a silicon-acrylic two-liquid reaction type. The paint forms a coating film that is compatible with the chromium plating surface. When the coating thickness is 15 μm or less, the chipping resistance is insufficient, and when the coating thickness is 25 μm or more, there is a possibility that interfacial peeling may occur due to cohesive failure, but as in the present invention, if the film thickness is 15 to 25 μm. In this case, sufficient chipping resistance can be obtained without fear of interface separation. In addition, since the silicone-acrylic two-component reactive paint is colorless and transparent, a desired color can be added by mixing a transparent pigment with the paint (for example, a metallic luster with a bluish tint or a yellowish tint). Metal luster, etc.), and achieves both mechanical durability and a design gloss color tone, thereby increasing the commercial value. Moreover, there is an excellent practical effect that the equipment cost and the running cost are lower than, for example, the sputtering process.

[Brief description of the drawings]

FIG. 1 is a schematic process diagram showing one embodiment of a method for forming a color clear coating film having chipping resistance according to the present invention, wherein (A) shows a water washing process and (B) shows a drying process. , (C) depicts the protection step, and (D) depicts the painting step. However, since it is drawn schematically,
It does not necessarily represent the implementation of the method of the invention in a realistic manner.

[Explanation of symbols]

1 ABS base (acrylonitrile / butadiene / styrene resin base member) 2 chrome plating 3 nozzle 4 pure water 5 blower 6 hot air 7 protection means 8 spray gun 9 ... Silicon-acrylic two-component reactive paint, 10 ... Transparent pigment, 11 ... Color clear coating film.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B05D 7/24 302 B05D 7/24 302Y

Claims (1)

(57) [Claims] 1. A method for forming a color clear coating film that gives a chromium-plated member a brilliant color other than the chrome-plated color and also provides chipping resistance to withstand external impact, comprising: a. Washing the chrome-plated surface with water; b. Drying so that no water droplets remain on the washed chrome-plated surface; c. Dried chromium plating surface is slimy 40 dynes /
means to protect the cleanliness of the chrome-plated surface so as to maintain cm; d. Silicon / acrylic 2 on clean chrome plated surface
Forming a clear coating film having a film thickness of 15 to 25 μm with a liquid reaction type paint, and mixing a transparent pigment in advance into the silicone-acrylic two-part reaction type paint described above. And characterized in that the clear coating film is a color clear coating film,
A method for forming a color clear coating film having chipping resistance.