JPS5919011B2 - Method for producing colored patterned sheets - 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 particularly to a method suitable for manufacturing synthetic leather with a colored pattern that closely resembles the pattern of dyed natural leather. It is something.

Generally, when dyeing natural leather, the dye does not diffuse and penetrate uniformly from the surface layer to the inner layer of the leather.Due to its texture and structure, the dye is dispersed relatively well in some areas, but
In other areas, the dye does not disperse and stagnates, resulting in the color tone of the leather surface changing due to 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. dyed brown-yellow,
In addition, it was considered that an important characteristic of natural leather is that a subtle change in color tone occurs in the transition area from the flat area to the valley area. 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.

The present invention has been made in view of the above circumstances, and provides a method for producing a sheet having a concavo-convex colored pattern in which the color tone of the transition area between the valley portion and the flat portion of the concavo-convex pattern is slightly changed. The purpose is to

That is, this invention uses a colored sheet as a base layer, and on the surface of the sheet, a surface layer made of at least one thermoplastic synthetic resin film colored in a color tone different from that of the sheet is laminated to obtain a laminated sheet. The thermoplastic synthetic resin film corresponding to the embossed valleys is melted and thinned and/or ruptured by heating and embossing the laminated sheet from the surface side, thereby changing the color tone of the valleys to the color tone of the base layer. and the color tone of the surface layer, or the color tone of the base layer itself, and the thickness of the surface layer gradually changes in the transition area from the valley to the surrounding flat area, thereby improving the color tone of this area. This is done in such a way that it changes slightly.

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. As the lower base layer 2, a sheet material such as a nonwoven fabric or a synthetic resin sheet colored in a predetermined color, for example, brownish-brown, is used. . As the resin for this base layer 2, it is desirable to use a resin with a high melting point that will not melt during the heat embossing process in the subsequent process. Laminated on the surface side of the base layer 2 is a surface layer 3 made of at least one thermoplastic synthetic resin film colored in a color different from that of the base layer 2, for example, golden brown.

Here, the term "color tone different from the color tone of 1 base layer 2" includes not only cases where the hues are different, but also cases where the same hue has different brightness and saturation.The thermoplastic resin used for the surface layer 3 is In order to easily melt during heat embossing, it is desirable that the melting point is as low as 80°C to 100°C, and the thickness is preferably about 40 to 100μ. A protective layer 4 made of a transparent or translucent thermoplastic synthetic resin film is laminated thereon.

This protective layer 4 is not necessarily provided in the present invention, but if it is provided, it is desirable that the protective layer 4 has a melting point equal to or higher than the melting point of the resin of the surface layer 3, and its thickness is 40°C. It is desirable that the thickness is about 100μ.
However, the 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 and the surface layer 3 and optionally laminated with the protective layer 4 is subjected to heat embossing to form an uneven pattern.

In this heat embossing process, it is sufficient to use a mold with unevenness in a predetermined pattern and heat it while applying pressure.The specific heat embossing means is arbitrary, but for example, the mold may be made of silicone rubber. High frequency dielectric heating can be 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 an uneven pattern corresponding to the uneven pattern of natural raw hide is formed. FIG. 2 shows the laminated sheet 1 using such a silicone rubber pressing die 5.
In this example, the above-mentioned uneven pattern is formed on the clay mold 5a, and the lower mold 5b is
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 mold 5 under the mold 5 is applied to the mold 5.
Pressure force is applied between a and 5b. The laminated sheet 1 between the upper and lower molds 5a and 5b generates heat from inside due to dielectric loss, and is partially pressed by the convex portions 6 of the upper mold 5a, thereby forming valleys 7 in the laminated sheet 1. At this time, the surface layer 3 of the laminated sheet 1 is melted and pressed by the convex portions 6 of the upper mold 5a, so that the portions corresponding to the convex portions 6, that is, the valley portions 1, are extremely thinned. If it progresses further, it will break. Therefore, when the protective layer 4 is colorless and transparent or when the protective layer 4 is not provided, when the laminated sheet 1 is viewed from the front side, the valleys are a combination of the color tone of the base layer 2 and the color tone of the surface layer 3. or the color tone of the base layer 2 itself. Further, when the protective layer 4 is colored and transparent, the color tone is a combination of the above-mentioned color tone and the color tone of the protective layer 4. Since the thickness of the surface 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. As is clear from the above description, according to the present invention, it is possible to obtain a concave-convex colored pattern in which the color tone of the transition area from the embossed valley to the surrounding flat area changes subtly. A sheet having a pattern very similar to the pattern can be obtained.

Of course, the method of the present invention is applicable not only to the production of sheets with patterns similar to those of natural leather, but also to the production of sheets with other patterns, such as geometric patterns. .

[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 heat embossing process of the present invention. 1... Laminated sheet, 2... Base layer, 3...
·····surface.

Claims (1)

[Claims] 1. A colored sheet is used as a base layer, and a surface 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 to make a laminated sheet, and this laminated sheet is A method for producing a colored patterned sheet, characterized in that heating embossing is performed from the surface side to melt and thin and/or melt and break the thermoplastic synthetic resin film in the embossed portion.