JPH0244587B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a method for forming a coating film on a high-intensity reflective plate that can be used for traffic signs, safety signs, signboards, etc. (Prior Art) Signboards, signboards, etc. that reflect high brightness even at night when exposed to light are already known. Most of these are made by pasting reflective tape or a reflective sheet on a substrate such as a metal plate or plywood. These have high brightness and reflectivity, but since they are not base materials themselves, the cost of attaching them to the substrate increases significantly.Also, in terms of quality, there are variations in adhesiveness and durability such as peeling from the substrate. It is also unstable in terms of For this reason, systems for directly coating the substrate have been studied, but they have not been able to provide the same high brightness and color as reflective tape. For example, in the Japanese Patent Publication No. 57-52905, as shown in Figure 1, colored paints 2 and 3 are applied as an undercoat to a substrate 1, dried, and then glass beads 5 are sprinkled on the substrate 1. After crimping, excess glass beads are removed and the coated surface is The method used is to apply a top coat of Clear 4 to the extent that the glass beads are not completely covered, but the process is complicated,
Dispersing the glass beads also requires special equipment, and there are limits to reflective performance. (Problems to be Solved by the Invention) The present invention aims to solve these problems and to stably and economically obtain a coating film with excellent reflectivity through a relatively simple process. be. That is, the present invention takes advantage of the high reflectivity of aluminum pigments, and uses a coating film containing 5 to 20% by weight of leafing or non-leafing aluminum pigment as a reflective layer, and on top of this, two coating films containing glass beads with reflexivity. It is characterized by being formed by a two-coat bake method. In order to improve the reflectivity, it is necessary to make the glass beads and the reflective layer as close as possible so that there is no extra substance intervening between them that would wastefully refract or reflect light. The most effective way to achieve this is to use leafing type aluminum as the undercoat, which allows the aluminum pigment to easily transfer to the surface in a layered manner. However, this method is limited to so-called achromatic coatings that do not contain any coloring pigments other than aluminum pigments. In the case of chromatic paint films, it is necessary to obtain high brightness without impairing the color, and after extensive research into methods that would suit this purpose, we found that disk-shaped non-leafing aluminum pigments with an average particle size of 40 to 60 μm are optimal. I found that. Since chromatic colors are mainly colors with clear images and relatively low hiding power, 5 to 20% by weight of aluminum pigment under the above conditions is used.
The chromatic undercoat layer contains light that passes through the chromatic coating and is reflected by the aluminum metal, resulting in high brightness. By the above method, a highly reflective coating film can be easily obtained in both achromatic and chromatic colors. The substrate used in the present invention is not particularly limited in material as long as it is a metal plate such as a steel plate, a galvanized iron plate, an aluminum plate, a stainless steel plate, a glass plate, a plastic plate, or a heatable smooth plate-like material. A coiled galvanized iron plate is most desirable in terms of workability, economy, and productivity. The undercoat used in the present invention has a number average molecular weight of 3000~
20000, Tg -5 to 40°C, and a resin acid value of 12 or less, the main resin component is a thermosetting synthetic resin such as polyester or acrylic, and it is essential that it contains 5 to 20% by weight of the aluminum pigment. In addition, the top coat is a transparent paint whose main component is the same resin as the base coat.
60 glass beads of 100 μm or less and a refractive index of 1.8 to 2.0
It is characterized by containing ~90% by weight. The refractive index of glass beads is 1.8 to 2.0 because they need to exhibit excellent recursivity.
A range of 1.9 is suitable, and 1.9 is optimal. Furthermore, particles with a uniform particle size of 100 μm or less in diameter are suitable for improving alignment during coating. Glass beads with a diameter of 100 μm or more are undesirable because they cause severe sedimentation in the paint and the coating workability is poor, and glass beads with a very small particle size are unsuitable because of poor reflectivity, and the optimum range is 66 μm to 10 μm. The method for forming the coating film of the present invention includes the usual coating methods used for sheet-like substrates, such as a roll coater, curtain flow coater, knife coater, bar coater, spray coater, and if necessary, pattern finishing with a pattern roll, and silk process. Graphic finishing etc. are used. The dry film thickness of the undercoat is preferably in the range of 7 to 25 μm, and the coating amount of the top coat is preferably in the range of 20 to 150 gr/m ² . Film thicknesses and coating amounts outside this range are not preferred because workability and coating performance are poor. As a heating method for the coating film, a conventional heating method used for baking paints, such as a hot air oven, an electric or gas infrared oven, or an electromagnetic induction heating oven, can be used. Embodiment FIGS. 2 and 3 are cross-sectional views of a coating structure formed according to the present invention, in which 11 and 21 are substrates, 12 is a leafing aluminum-containing undercoat including an aluminum layer 12a and a clear layer, 22 is aluminum 2
Coarse non-leafing aluminum-containing undercoat consisting of 2a and colored layer 22b, 14 and 24 are undercoat 12,
Glass beads sprinkled and crimped onto 22, 1
Reference numerals 3 and 23 denote clear top coat layers that are applied to an extent that does not completely cover the glass beads 14 and 24. FIG. 4 is a schematic diagram showing the coating film forming process,
An uncoiler 3
1, it is passed through a chemical conversion treatment tank 33 for chemical conversion treatment, then passed through an undercoat roll coater 34 to apply an undercoat of thermosetting synthetic resin paint containing aluminum pigment, and then passed through an undercoat oven to bake or heat it. , cured, and then passed through a top coat roll coater to apply a top coat of a thermosetting synthetic resin transparent paint containing glass beads, followed by a top coat oven 37 to bake or heat cure the top coat, and finally a recoiler 38 Wind it up to obtain a high-intensity reflector. Examples of the present invention will be described below based on experimental results. Experimental conditions 1 1 Substrate type, 0.27 mm thick chemical conversion treated galvanized iron plate, 2 Undercoat, resin type, manufactured by Mitsui Toatsu Chemical Co., Ltd., Almatex P-645, oil-free alkyd resin, Color, white...Titanium white pigment White Silver …Non-leafing aluminum pigment, aluminum paste JSO− manufactured by Toyo Aluminum Co., Ltd.
800 White Silver...Leafing aluminum pigment, Sap110 manufactured by Showa Aluminum Co., Ltd. Aluminum pigment addition amount is 10% by weight in both cases Dry film thickness, 12μ 3 Top coat, resin type, Almatex P-646 manufactured by Mitsui Toatsu Chemical Co., Ltd., oil Free polyester resin Glass beads, diameter, 66 μm> Refractive index, 1.5, 1.9, 2.2 Content, 50-95% by weight Coating amount, 60 g/m ² dry Paint viscosity, #3 Zahnkup 90 seconds 4 Coating film performance, reflective performance, According to 7.3 of JISZ9117 Processability, tape peeling after bending 180°OT in a vise 5 Results, based on experimental results 1.

[Table] From the above experimental results, the leafing aluminum pigment has the best reflective performance, and the glass beads have the best refractive power of 1.9, and from the viewpoint of balance with processability, the amount of glass beads is preferably 60 to 90% by weight. Experimental conditions 2 1 Substrate type, 0.27 mm thick chemically treated galvanized iron plate 2 Undercoat, resin type, same as above experimental condition 1 Color, Yellow Red Blue Non-leafing aluminum pigment with or without addition Amount 5.20% by weight Aluminum Type: Scale-like with an average particle size of 10 to 30 μm Disc-like with a diameter of 40 to 60 μm Dry film thickness, 12 μm 3 Top coat, resin type, same as experimental conditions 1 above Glass beads, diameter, 66 μm > refractive index, 1.9 Content, 80% by weight Coating amount, 60 g/m ² Paint viscosity, #3 Zahn Cup 90 seconds 4 Paint film performance, color, visual and color tone when exposed to light Reflection performance, according to 7.3 of JIS Z9117 5 Results, based on experimental results 2.

[Table] As shown above, when colored objects without aluminum pigments are exposed to light, they lose their tone and become achromatic, resulting in differences from the reference plate. In addition, the value of reflection performance is also low. When a scaly non-leafing aluminum pigment is mixed, the color under natural light becomes poorer as the amount added increases.
However, when non-leafing aluminum with an average particle size of 40 to 60 μm according to the present invention is mixed, the reflective performance is improved compared to the case without aluminum pigment, and the color when exposed to light becomes stable. The best value is around 15% in terms of color and reflection performance. Furthermore, the coating specifications of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1, and the comparison with comparison materials and reflective sheets is shown in Table 2.
Indicated by

【table】

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【table】

[Table] As shown in Table 2 above, from the results of achromatic white silver in Example 1 and Comparative Example 1, leafing aluminum pigments are superior to non-leafing aluminum pigments in terms of reflection performance. It is comparable to the reflective sheet of comparative material 1. In addition, from the results of chromatic red in Example 2 and Comparative Example 2, the color when exposed to light was excellent with the addition of disc-shaped non-leafing aluminum with an average particle size of 40 to 60 μm.
The reflective performance is also close to that of the comparative reflective sheet. Effects of the Invention The method for forming a high-brightness reflective coating according to the present invention not only allows the production of a high-brightness reflector through a relatively simple process as described above, but also provides a highly retroreflective and reflective plate. It has optical color reproducibility, excellent processability, corrosion resistance, and weather resistance, and can be obtained stably and economically. The high-intensity reflector produced by the method of the present invention is generally used for signboards, various signboards, automobile license plates, bicycle mudguard covers, guardrail cap materials, etc.
It can also be used in applications that require durability, and can be expected to have a wide range of usefulness.

[Brief explanation of drawings]

Fig. 1 is a state diagram when spraying, pressure bonding and clear coating are applied by the conventional method, Figs. 2 and 3 are sectional views of the coating film formed by the present invention,
FIG. 4 is a schematic diagram showing the process of forming a coating film in accordance with the method of the present invention. 1... Substrate, 2... Colored layer, 3... Intermediate colored layer, 4...
Clear coating film, 5...Glass beads, 11...Substrate,
12...Leafing aluminum-containing undercoat, 12a...aluminum layer, 12b...clear layer, 13...topcoat clear layer, 14...glass beads, 21...substrate, 22...
Coarse non-leafing aluminum-containing undercoat, 22a...
Aluminum, 22b... colored layer, 23... topcoat clear layer, 24... glass beads, 31... uncoiler,
32... Belt-shaped metal plate, 33... Chemical conversion treatment tank, 34... Undercoating roll coater, 35... Undercoating oven, 36
...Top coating roll coater, 37...Top coating oven,
38...Recoiler.

Claims (1)

[Claims] 1. Flat or band-shaped metal plate, plastic plate,
Apply 5 to 20 coats of aluminum pigment as a base coat to a substrate such as plywood.
After applying 7 to 25 μm of thermosetting synthetic resin paint containing 7 to 25 μm by weight and heating and curing, apply 20 g/m ² to 150 g of thermosetting synthetic resin transparent paint containing 60 to 90 weight percent of glass beads with a diameter of 100 μm or less as a top coat. A method for forming a high-brightness reflective coating film, which is characterized by coating / m ² and curing by heating. 2. The method for forming a coating film according to claim 1, wherein the pigment used in the achromatic undercoat is a leafing aluminum pigment. 3 The average particle size of the pigment used in chromatic primer paint is 40.
2. The method for forming a coating film according to claim 1, which is a disc-shaped non-leafing aluminum pigment of ~60 μm.