JPS5919012B2 - Method for producing colored patterned synthetic sheet - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method of manufacturing a synthetic sheet with a colored pattern, and more specifically, to a method of manufacturing synthetic leather with a colored pattern that closely resembles the pattern of dyed natural leather. It is.

Generally, when dyeing natural leather, the dye does not diffuse uniformly from the surface layer to the inner layer of the leather, and due to differences in the texture and structure, the dye is dispersed relatively well in some areas, while in other areas. In this case, the dye does not disperse and stagnates, and as a result, the color tone of the leather surface changes depending on the differences in its texture and structure, resulting in a complex color pattern. For example, when crocodile leather is dyed with golden brown dye, the degree of dyeing differs between the valleys and flat areas of the uneven pattern on the surface of the crocodile leather, and while the flat areas are well dyed golden brown, the troughs are dyed lightly. It is dyed brown-yellow, and a subtle change in tone occurs in the transition area from the flat part to the valley part. The occurrence of such subtle color changes was considered to be an important feature of natural leather. However, conventionally, when artificial leather is embossed to form an uneven pattern similar to that of natural leather, and then colored, the troughs and flat areas of the uneven pattern are colored differently, so it is difficult to clean the valleys. ” and printing methods have been adopted, but with these methods, it is possible to simply make the color tone of the valley and the flat part different, but the color tone of the transition part from the flat part to the valley can be made different. It has been difficult to make subtle changes in the texture as in the case of natural leather.

This invention was made in view of the above-mentioned circumstances, and aims to produce a synthetic sheet having a colored embossed pattern in which the color tone of the transition area between the troughs and flat areas of the uneven pattern changes subtly. The purpose is to provide a method.

That is, this invention uses a colored synthetic resin sheet as a base layer, and on the surface of the base layer is laminated an intermediate layer consisting of at least one thermoplastic synthetic resin film colored in a color tone different from that of the base layer. A protective layer made of transparent or translucent thermoplastic synthetic resin is laminated on the surface of the intermediate layer to form a laminated sheet, and the laminated sheet is heat-embossed by high-frequency dielectric heating using a mold made of silicone rubber. In the heat embossing process, the intermediate layer is melted preferentially over the protective layer, so that the intermediate layer in the embossed valleys is melted and thinned or/} and ruptured, as described above. By thinning and/or breaking the intermediate layer of the embossed valleys, the color tone of the valleys becomes a composite tone of the base layer color and the intermediate layer color tone, or the color tone of the base layer itself, and The thickness of the intermediate layer changes in the transition area from the area to the surrounding flat area, which causes the color tone of the valley to change subtly. At the same time, silicone rubber stamping and high-frequency dielectric heating are used for heat embossing. When used, the intermediate layer is melted preferentially to the protective layer, thereby maintaining a good surface condition of the protective layer.

This invention will be explained in detail below based on the accompanying drawings.
FIG. 1 is a diagram showing an example of a laminated sheet 1 used in the present invention, and the lowermost base layer 2 is made of artificial leather colored in a predetermined color, for example, brownish-brown (for example, a material known by the trade name 1 Clarino). ) and other synthetic resin sheets are used.

As the resin for this base layer 2, a resin with a high melting point that does not melt during the heat embossing process in the subsequent step is used. On the surface side of the base layer 2, a color tone different from that of the base layer 2,
For example, an intermediate layer 3 made of at least one thermoplastic synthetic resin film colored golden brown is laminated thereon.

Here, the color tone 1 that is different from the color tone of the first base layer 2 includes not only a case where the hue is different, but also a case where the same hue has a different saturation or a different lightness. The thermoplastic resin used for this intermediate layer 3 desirably has a low melting point of about 80°C to 100°C so that it can be easily melted in the subsequent heat embossing process, and its thickness is 0μ to 10μ.
It is desirable that it be about 0μ. Further, on the surface side of the intermediate layer 3, a protective layer 4 made of a transparent or translucent thermoplastic synthetic resin film is laminated.

The thermoplastic resin used for this protective layer 4 may have a melting point comparable to that of the resin for the intermediate layer 3, but it is preferable that the melting point is higher than that of the resin for the intermediate layer 3, and the thickness is 40°C.
It is desirable that the thickness is about μ to 100 μ. Protective layer 4
may be colorless and transparent, or may be colored and transparent. As described above, the laminated sheet 1 composed of the base layer 2, intermediate layer 3, and protective layer 4 is subjected to heat embossing to form an uneven pattern.

In this heat embossing process, a mold made of silicone rubber or the like is used, and high frequency dielectric heating is used as the heating means. The silicone rubber mold may be one in which a silicone rubber solution is poured onto the surface of a natural raw hide such as crocodile skin and cured, thereby transferring the uneven pattern on the surface of the natural raw hide. That is, it is sufficient to use a silicone rubber mold in which unevenness is formed that corresponds to the uneven pattern of natural raw hide. FIG. 3 is a diagram showing a state in which heat embossing is applied to the laminated sheet 1 using such a silicone rubber stamping die 5. In this example, the above-mentioned uneven pattern is formed on the upper die 5a, and the lower die 5b No particular uneven pattern is formed on the surface. In this embossing process, a high frequency voltage is applied to the mold 5 by an external electrode (not shown), and a pressing force is applied between the upper and lower molds 5a and 5b of the mold 5. Upper and lower molds 5a, 5
The laminated sheet 1 between portions b generates heat from within due to dielectric loss, and is partially pressed by the convex portion 6 of the upper mold 5a, thereby forming a valley r in the laminated sheet 1. At this time,
Since the intermediate layer 3 of the laminated sheet 1 is melted and pressed by the convex portions 6 of the upper die 5a, it becomes extremely thin in the portions corresponding to the convex portions 6, that is, in the valleys 1. If this becomes significant, it will lead to breakage. Therefore, if the protective layer 4 on the surface is colorless and transparent, the valleys 7 of the laminated sheet 1 will have a color tone that is a combination of the color tone of the base layer 2 and the color tone of the intermediate layer 3 when viewed from the surface side. Alternatively, the color tone of the base layer 2 itself appears. Further, if the protective layer 4 is colored and transparent, the valley r has a color tone that is a combination of the above-mentioned color tone and the color tone of the protective layer 4. Since the thickness of the intermediate layer 3 gradually changes in the transition part from the valley r to the surrounding flat part 8, the color tone changes slightly in this part. In addition, in the above-mentioned hot embossing process, since silicone rubber has a small dielectric loss, the silicone rubber mold 5 does not generate much heat due to high frequency dielectric heating, and its temperature rise is small.

On the other hand, the laminated sheet 1 generates heat from inside by high-frequency dielectric heating. Since the protective layer 4 on the surface of the laminated sheet 1 is in contact with the silicone rubber mold 5 where the temperature rise is small, its temperature does not rise much, whereas the temperature of the intermediate layer 3 rises due to internal heat generation. Therefore, the intermediate layer 3 is heated (heated) preferentially relative to the protective layer 4 and is preferentially melted. That is, since the intermediate layer 3 is melted before the protective layer 4 melts, when the protective layer 4 melts, the lower surface side of the protective layer 4 fuses with the molten intermediate layer 3, so that the protective layer 4
It is possible to prevent the situation where the surface condition becomes poor due to individual shrinkage. Here, assuming that the protective layer 4 on the surface melts before the intermediate layer 3, in this case, the protective layer 4 separates from the intermediate layer 3 in a solid state and contracts independently, resulting in a poor surface condition. I become confused. In the present invention, such a situation can be prevented by using high frequency dielectric heating and a silicone rubber mold. As mentioned above, in this invention, the intermediate layer is melted preferentially than the protective layer by using high-frequency dielectric heating and a silicone rubber mold, or of course the melting point of the resin in the intermediate layer is higher than that of the protective layer. By selecting the material so that the melting point is lower than the melting point of the resin, the above-mentioned preferential melting can be achieved more reliably. As is clear from the above explanation, according to the method of the present invention, it is possible to subtly change the color tone of the transition area from the embossed valley to the surrounding flat area,
Therefore, it is possible to obtain a pattern that is very similar to the pattern obtained when natural leather is dyed. And since this invention provides a sheet with a transparent or semi-transparent protective layer on its surface,
It is possible to obtain a surface appearance that closely resembles the mirror finish of natural leather, and by using a silicone rubber mold and high-frequency dielectric heating for heat embossing, the intermediate layer is melted prior to the protective layer. From this, it is possible to obtain a patterned sheet with a good surface condition by maintaining the surface condition of the protective layer in a good condition.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view showing an example of a laminated sheet used in the present invention, and FIG. 2 is a schematic diagram showing step-by-step an example of the force-u heat embossing process of the present invention. 1... Laminated sheet, 2... Base layer, 3...
...Intermediate layer, 4...Protective layer, 5...
...Silicone rubber mold, 7...Tanibe.

Claims (1)

[Claims] 1. A colored synthetic resin sheet is used as a base layer, and an intermediate layer made of at least one thermoplastic synthetic resin film colored in a color tone different from that of the base layer is laminated on the surface of the base layer,
Furthermore, a protective layer made of a transparent or translucent thermoplastic synthetic resin is laminated on the surface of the intermediate layer to make a laminated sheet, and the laminated sheet is heat-embossed by high-frequency dielectric heating using a mold made of silicone rubber. A colored patterned synthetic sheet, characterized in that, in the heat embossing process, the intermediate layer is melted preferentially to the protective layer, and the intermediate layer in the embossed valleys is melted and thinned and/or melted and ruptured. manufacturing method.