CS277151B6 - A method for forming flat flexible materials, in particular leather - Google Patents

Abstract

The purpose of the solution is to improve the method of shaping flat flexible materials, especially leather, by pressing in a mold provided with a negative of the desired relief (rl). The stated purpose is achieved by adhering, before pressing, to the flat flexible material formed by, for example, part (1), a layer of lightweight plastic material, for example part (2), which is preheated to the shaping temperature and is shaped together with the flat flexible material during pressing. In addition to the above features, there are other possible variants. The solution can be used in the production of haberdashery, shoe uppers, clothing, etc.

Description

The invention relates to a method of shaping flat flexible materials, in particular leather, by pressing in a mold provided with a negative of the desired relief.

Flat flexible materials, such as natural or artificial leather, etc., have a relatively elastic structure and are therefore difficult to shape. Most often, these materials are formed by a passage between two rollers, one of which has a pattern formed on the surface which is a negative of the desired relief. In this shaping method, the pressing time of the material to be processed is limited only to passing through the shaping slot of the two rollers. Therefore, only reliefs with a maximum depth of a few tenths of a millimeter can be created in this way. Various molds are used to form reliefs of greater depth, in which pre-cut pieces of flat flexible material are usually molded. These parts form a semi-finished product of the final product, e.g. handbags, briefcases, shoe uppers, gloves, etc. In both of these shaping methods, in addition to pressure, the effect of heat is often used, which advantageously impairs the shape memory of the processed material. One of the rollers or the relevant part of the mold is heated and the heat is transferred to the material to be processed, which ultimately results in increased stability of the formed relief. However, natural or artificial leather can only be heated to a relatively low temperature and the heating time is also limited. If these limits are exceeded, natural leather, in particular on the face, is thermally damaged by natural leather. Artificial leathers usually have a face layer interconnected by a plastic material. If this plastic material is heated to the value of the forming temperature, the entire face layer is disturbed. The shaping of natural or artificial leather without the use of the thermal effect requires an increase in pressure and, in particular, an extension of its duration of action. However, even after the pressure is released, the material partially returns to its original state due to its shape memory. Increasing the pressure and prolonging its duration increases production costs and decreases labor productivity.

These disadvantages are eliminated by the shaping method according to the invention, the essence of which consists in that a layer of foamed plastic material is adhered to the flat material before pressing, which is pre-heated to the shaping temperature and formed together with the flat flexible material during pressing. The foamed plastic material is pressed to a smaller thickness. The lightweight plastic material is polyolefin. The flat flexible material is pressed against the mold projections. The flat flexible material is pressed against the recesses of the mold.

A higher effect of the invention is that a layer of foamed thermoplastic material, which is formed at the same time as the flat flexible material, fixes its shaped relief. The shaping of the expanded thermoplastic material is relatively easy and permanent after its heating to the shaping temperature, this heating being carried out separately, thus completely eliminating the damage to the flat flexible material by the action of heat. Spatial reliefs below or above the face level can be created on a flat flexible material. The layer of foamed plastic material creates reinforcement of the semi-finished parts of the final products. This reduces the need to provide these semi-finished parts with a reinforcing lining. In the shaping method according to the invention, it is possible to use very simple molds, the protrusions and depressions of which are formed, for example, from cardboard, plywood, etc.

materials that can be easily machined. This makes it possible to change the reliefs created very quickly according to the changing 'requirements of fashion.

Examples of embodiments of the method are schematically shown in the drawings, where Fig. 1 shows a cross-section of natural leather with a layer of expanded polyolefin before gluing, Fig. 2 a cross-section of a mold when forming a depression in the shape of a depression below the face level; shaping the relief in the form of a protrusion above the level of the face, and Fig. 5 is a perspective view of a handbag with shaped reliefs.

Example 1

The flat flexible material forms part 1 (Fig. 1) of natural leather. An adhesive layer 11 is formed on the reverse side of the part 1. From the layer of expanded polyethylene, which has a nominal thickness hl, a part 2 is prepared, the outline of which corresponds to the contour of the part 1 of natural leather, and on one side of it an adhesive layer 21 is formed. Then, the part 2 is heated in a preheating chamber (not shown) to the molding temperature of the polyethylene and applied by the coating 21 to the adhesive application 11 of the part 1. When heating the part 2, the adhesive application 21 is preferably activated and The glued materials are then centered by the face 12 of the part 1 against the protrusion 41 (Fig. 2) of the matrix part 4 of the mold. The protrusion 41 has a negative shape of the desired relief r1. Then the male part 5 of the mold, which is already formed by the planar plate, is pushed and pressed into the matrix part 6. After the pressing of the natural leather part 1 and together with it the foamed polyethylene part 2, they take on the shape of the protrusion 41. The polyethylene material of the part 2, which is heated to the shaping temperature, is permanently deformed and . This reduces the nominal thickness hl of the part 2 to the thickness h2 and at the same time increases its density. On the natural leather part 1 a relief r1 is formed in the shape of a depression below the level of the face 12. The shaped part 2 and in particular its denser and thus stiffer part with a thickness h2 permanently fixes the shaped relief r1 of the natural leather part 1. The parts 1 and 2 together form, for example, a semi-finished part 31 (FIG. 5) of a handbag k, on which a relief r1 can be formed according to Example 1.

Example 2

A part 1 of natural leather and a part 2 of foamed polyethylene are prepared and glued according to Example 1 and a face with a face 12 against the recess 61 (Fig. 4) of the matrix part 6 of the mold. The recess 61 has a negative shape of the desired relief r2. Then the male part 7 is pushed and pressed into the matrix part 6, which is provided with a protrusion 71 against the recess 61. After pressing the mold, the natural leather part 1 and together with it the foamed polyethylene part 2 take the shape of a depression 61. forming temperature, it is permanently deformed and its lightened structure is compressed into a denser structure, whereby its nominal thickness h1 is reduced to the thickness h2. Pressing the part d2 to the thickness h2 increases its rigidity. A relief r2 in the form of a protrusion above the level of the face 12 is thus formed on the natural leather part 1. The shaped part 2 pressed and pressed to the thickness h2 permanently fixes the shaped relief r2 of the natural leather part 1. The parts 1, 2 together form, for example, a semi-finished part 31 of a handbag k, on which a relief r2 can be formed according to Example 2. The semi-finished product part 31 is further processed by the usual haberdashery technology of handbag production. »

When creating reliefs r2 above the level of the face 12 of the part 1 in the form of protrusions of smaller height, the male parts 7 (Fig. 3) in the form of a planar plate can be used. In this case, the natural leather part 1 together with the expanded polyethylene part 2 is also pressed against the recess 61 of the matrix part 6 of the mold. At the location of the recess 61, the part 2 is compressed less, while outside this recess 61 it is compressed more, to a thickness h2.

The invention can be used for shaping flat flexible materials, especially leather, in the production of fancy goods, uppers, garments, etc.

Claims (5)

PATENT CLAIMS 1. A method of forming flat flexible materials, in particular leather, by pressing in a mold provided with a negative of the desired relief, characterized in that a layer of expanded plastic material is adhered to the flat flexible material before pressing, which is preheated to the molding temperature and formed together during pressing with flat flexible material. The shaping method according to claim 1, characterized in that the expanded plastic material is compressed to a smaller thickness. The molding method according to claim 1, characterized in that the expanded plastic material forms a polyolefin. The shaping method according to claim 1, characterized in that the flat flexible material is pressed against the projections of the mold. The shaping method according to claim 1, characterized in that the flat flexible material is pressed against the recesses of the mold.