FI68506B - BAKKAPPA FOER SKO - Google Patents

Description

1 68506

Back stiffener for the shoe

The invention relates to a back stiffener for a shoe formed of a thermoplastic shaped body.

The use of the back stiffener in the shoe is based on providing a fixed support for the foot on the one hand and on the other hand for maintaining the pre-given shape of the shoe for a long time. Thus, according to the current state of the art, the back stiffeners consist of very hard materials, for example a material based on leather fibers. These materials are usually made as a sheet material and deep drawn into the desired shape. The thickness of the sheet material is usually the same in all areas and thus it is necessary to chamfer the back stiffener at least in the area of the upper edge if a pleasant-looking transition from the shoe to the wearer's foot is desired. This separate work step is complex and expensive.

20 Thus, the production of back stiffeners by injection molding of thermoplastics has already been proposed. However, this presupposes the manufacture of expensive tools. In addition, due to the required cooling time, only a relatively low production rate is possible. Thus, even this 25 solution does not eliminate the existing inconvenience.

The invention is based on the development of a back stiffener which, on the one hand, can be manufactured very economically and, on the other hand, provides easy support for the foot due to its easy adaptability.

According to the invention, this object is achieved in that the shaped body is a deep-drawn thermoplastic film with a thickness of 0.5 to 2.5 mm, on the inner surface of which a layer of closed cells, foamed, crosslinked polyolefin with a thickness of

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2 68506 decreases steadily as you move toward the edges. The plastic film is preferably high-density polyethylene with a thickness of 0.5-1.3 mm. Its thickness is the same in all areas so that instinct in the upper-5 edge area is not required.

The inner surface of the plastic film is coated with a layer of polyolefin foam, preferably closed cells, foamed and crosslinked polyethylene with a maximum thickness of 2.5 mm. The layer is applied to the surface of the plastic film 10 most simply using a flame coating. In this case, it is only necessary to take into account that the welding between the materials used is carried out in such a way that the foam structure is not damaged. In addition, the inherent stiffness of the resulting material is so high that the formation as a real back stiffener can be performed locally separately from the production of the starting material.

For shaping, the material is evenly heated to the required shaping temperature and, if desired, deep-drawn in a combined stamping-pressing tool.

Preferably, the thickness of the foam layer is reduced to the desired degree in the edge areas in the same working step by compacting the pore structure. The desired purpose, namely a uniform reduction in thickness in the region of the upper edge, can then be achieved in a particularly simple and efficient manner. Another positive effect is based on the fact that the strength of the compacted foam structure in the edge areas is not significantly reduced compared to the original foam material. The inner part of the rear stiffener also forms a cushion, which is known to be comfortable due to the comfort of use achieved and which prevents the heel of the wearer from slipping off the shoe when walking.

An example of the implementation of a rear stiffener according to the invention is shown in the accompanying drawing.

3 68506

Figure 1 shows a perspective view of the rear stiffener seen from above.

Figure 2 shows a cross-section of the rear stiffener according to Figure 1.

The back stiffener according to Figure 1 consists of a deep-drawn plastic film 1 made of highly compacted polyethylene. The necessary use of this material is not required, but a film of ABS or PVC plastic can also be used if desired. However, when using such films other than foam, the required and advantageous shaping conditions must be tested in individual cases.

The inner surface of the non-porous plastic film 1 is coated with a foam layer 2, the thickness of which towards the edges is uniformly reduced. The simplest way to reduce the thickness of the foam layer can be achieved by relatively compacting the foam structure of the foam layer 2. The appearance of the finished back stiffener is very pleasant, which has a beneficial effect on its use in fashion shoes, especially women's shoes.

Claims (5)

A back stiffener for a shoe consisting of a thermoplastic molding, characterized in that the molding is a deep-drawn thermoplastic film (1) with a thickness of 0.5-2.5 mm, on the inner surface of which a closed cell, foamed, crosslinked polyolefin is applied. a layer whose thickness decreases uniformly as it moves toward the edges. Rear stiffener according to Claim 1, characterized in that the plastic film (1) consists of polyethylene and has a thickness of 0.5 to 1.3 mm. Back stiffener according to Claims 1 and 2, characterized in that the polyolefin foam layer (2) consists of closed-cell, foamed, cross-linked polyethylene and has a maximum thickness of 2.5 mm. Rear stiffener according to Claims 1 to 3, characterized in that the plastic film (1) and the foam layer (2) are connected to one another by means of a flame coating. Rear stiffener according to Claims 1 to 4, characterized in that the thickness of the foam layer (2) is reduced by sealing the pore structure.