JPH032648B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an embossing method for imparting a beautiful embossed pattern to a leather-like sheet made of a fibrous substrate and a thermoplastic elastic resin without impairing its texture.

[Prior art and problems to be solved by the invention]

BACKGROUND ART Conventionally, a heat embossing method has been widely used as a method for imparting a pattern to a leather-like sheet made of a fibrous base and a thermoplastic elastic resin by embossing. This method uses a heated embossing device consisting of a patterned heated metal roll or heated metal endless belt and a highly hard back roll.
A flexible sheet is pressed all at once under high pressure onto a metal surface that has been heated to over 100 degrees Celsius to create a pattern, much like a branding iron. Therefore, if a pattern is to be beautifully applied, high temperature and pressure are required. However, unlike ordinary fabrics, leather-like sheets are thick and have low apparent density, so they are easily compressed in the thickness direction, and even if a beautiful embossed pattern is applied to the surface, the sheet becomes less sublime and less flexible. It deteriorates and the texture becomes inferior. In addition, embossing methods include preheating the sheet in advance and then embossing it to make a leather-like sheet, or after embossing, leaving the embossed sheet in close contact with the metal surface for a while to anneal the surface. There are also methods of peeling it off (Special Publication No. 47-24662, etc.). However, in either method, high temperature and high pressure are still required during embossing, so the texture of the leather-like sheet cannot be improved. In addition, an embossing device using a soft backroll with a rubber JIS hardness of 40 to 80 degrees was developed in 17347.
This embossing device, proposed in the above publication, sandwiches a thin, non-compressible workpiece such as cloth or paper between a resin embossing roll and a rubber back roll, and the soft back roll is used as the embossing roll. The emboss process is carried out by deforming the material to match the surface irregularities of the material, so to speak, by sandwiching the object between the male and female dies.Thick, flexible, and easily compressible leather-like sheets can be embossed using this equipment. However, a beautiful embossed pattern cannot be obtained and the texture cannot be improved. An object of the present invention is to provide a method for imparting a beautiful embossed pattern to the surface of a leather-like sheet that is sublimely flexible and has an excellent texture without impairing the texture.

[Means to solve the problem]

The present invention provides a method for heat-embossing a leather-like sheet made of a fibrous substrate and a thermoplastic elastic resin between a metal roll or a metal endless belt and a back roll, in which the back roll has a hardness of 20 degrees or more as measured by a rubber JIS hardness meter. 2 The outer layer of a rubber roll with a hardness of less than 100 degrees is covered with a sponge layer with a hardness of 5 degrees or more and less than 100 degrees as measured by an Asuka type C hardness meter.
This is a leather-like sheet embossing method characterized by hot embossing using a layered backroll.

[Effect]

The method of the present invention will be explained according to the drawings. Fig. 1 is a cross-sectional view of the back roll used in the method of the present invention, and Fig. 2 is its sketch. A sponge layer 3 with a hardness of 5 degrees or more and less than 100 degrees on a C-type hardness tester is attached. Third
The figure is a cross-sectional view of a leather-like sheet embossed by the method of the present invention. The sponge layer on the back roll surface is soft and compressible, so it deforms greatly, and the leather-like sheet 4 is heated in the region A. The sheet is pressed against an embossing roll, and the thermoplastic elastic resin on the surface of the sheet is heated and softened (preparation zone). The leather-like sheet whose surface resin has been softened is strongly pressed against an embossing roll near point C, where the maximum pressure is applied, and an embossed pattern is imparted to it (pressure embossing point). The leather-like sheet continues to be pressed against the embossing roll in area B, and then in area C.
The embossed pattern provided at the points is heat fixed (heat treatment fixing band). The important thing here is first of all that the surface of the back roll is covered with a compressible sponge layer. If the back roll is covered only with a non-compressible rubber layer, it is difficult to greatly deform the back roll as in the present invention, and even if it is sufficiently flexible and can be greatly deformed, However, when the back roll is used under conditions that greatly deform it as in the method of the present invention, a large shearing force is applied in the circumferential direction of the rubber layer from point C to area A as the roll rotates. It will be destroyed. Next, it is important to provide a rubber layer inside the sponge layer, which is harder than the sponge layer but softer and more easily deformed than the metal core. This rubber layer disperses the embossing pressure, making it possible to make the width of the preheating zone and heat treatment fixing zone wider. As a result, the pressure distribution from the beginning of the preheating zone to the end of the heat treatment fixing zone becomes smoother, making it suitable for use in applications ranging from flexible leather-like sheets suitable for clothing and gloves to casual clothes, bags, bags, etc. It is possible to emboss even slightly hard or thick leather-like sheets without sacrificing their texture. In this way, the combination of a pair of embossing rolls and back rolls was achieved for the first time by using a back roll with two coating layers: a rubber layer covering the outside of the metal core, and a soft sponge layer covering the outside. It became possible to add beautiful embossed patterns to leather-like sheets without damaging their texture.

【Example】

Example 1, Comparative Examples 1 and 2 In Fig. 1, fiber entanglement was carried out using a back roll having a structure in which the outer layer of a rubber roll with a rubber JIS hardness of 45 degrees was covered with a sponge layer with a hardness of 30 degrees as measured by an Asuka type C hardness meter. A flexible leather-like sheet used for clothing with a thickness of approximately 0.7 mm, consisting of a base layer made of non-woven fabric containing porous polyurethane and a thin layer of non-porous polyurethane on its surface, was embossed at 135°C with an embossing roll.
The sheepskin grain was embossed at a gauge pressure of 3.5 kg/cm ² and a feed rate of 5 m/min. At this time, the back crawl was greatly deformed as shown in Figure 3. The obtained leather-like sheet had a beautiful embossed pattern on its surface, and its thickness and texture were almost unchanged compared to before the embossing process. For comparison, when embossing was carried out in the same manner using a silicone rubber roll with a JIS rubber hardness of 40 degrees as a back roll, the deformation of the back roll was smaller than in the example. Although the embossed pattern on the surface of the obtained leather-like sheet was somewhat unclear, the thickness was reduced to about 0.55 mm and the texture was hard. Furthermore, for comparison, embossing was carried out in the same manner as a back roll, using a sponge roll in which a sponge with a hardness of 30 degrees measured by an Asuka type C hardness tester was wound directly around the iron core. The back roll was greatly deformed as shown in FIG. 3, and the thickness and texture of the leather-like sheet remained almost unchanged, but the embossed pattern on the surface was somewhat unclear. Gauge pressure 4.0Kg/
When the embossing pattern was increased to cm ² , the embossed pattern became clearer, but the thickness decreased to 0.6 mm and the texture became harder.

【Effect of the invention】

According to the method of the present invention, a beautiful embossed pattern can be imparted to a leather-like sheet in one step without using large-scale equipment, and the texture of the leather-like sheet is not impaired. Further, in order to carry out this method, only the back roll of a conventional hot embossing device needs to be replaced, so that the cost and time for modification are saved.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the back roll of the embossing device used in the present invention, Figure 2 is its sketch, and Figure 3 is a cross-sectional view of the back roll of the embossing device used in the present invention.
The figure is a cross-sectional view of a leather-like sheet in an embossed state according to the method of the present invention. The symbols in the figure are 1: iron core, 2: rubber layer, 3: sponge layer, 4: leather-like sheet, 5: back roll, 6: embossing roll, A: preheating zone, B: heat treatment fixing zone, C: heat treatment fixing zone. Pressure embossed point.

Claims (1)

[Claims] 1. In a method of hot embossing a leather-like sheet made of a fibrous base and a thermoplastic elastic resin between a metal roll or endless metal belt and a back roll, the hardness of the back roll measured with a rubber JIS hardness meter is 20 degrees or more and less than 100 degrees. A method for embossing a leather-like sheet, characterized in that the outer layer of a rubber roll is heat-embossed using a back roll having a two-layer structure in which the outer layer of a rubber roll is covered with a sponge layer having a hardness of 5 degrees or more and less than 100 degrees as measured by an Asuka type C hardness meter.