JPH01195028A - Method for molding soft pad - Google Patents

Abstract

PURPOSE:To easily control the temp. of a mold and to apply no destructive power to a skin material, by preparing a prefoam body, wherein an urethane slab becoming a foam layer and a thermoplastic resin becoming a base material are bonded under pressure by preparatory molding and subsequently setting the preform body to a slash mold to which a semi-molten skin material becoming a skin is sticked to apply hot contact bonding molding to the skin material and the preform body. CONSTITUTION:A compression mold 4 having a necessary clearance with respect to a skin mold 1 is heated to 210 deg.C and claming is performed by the mold 4 and the skin mold 1 to apply hot contact bonding molding to a thermoplastic resin 3 and an urethane slab 2, and a preform product 5 having an intermediate shape is obtained. A skin material 6 is prepared by slash molding using the skin mold 1. Succeedingly, clamping for compressing the preform product 5 by the skin mold 1 (200 deg.C) having the skin material 6 sticked thereto and the compression mold 4 is performed. The preform product 5 is cured in a compressed state and subsequently cooled and demolded to obtain a soft pad.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applied to the skin, which is used for automobile interior parts, etc.
This invention relates to a method for molding a soft pad having a laminated structure of a foam layer and a base material.

<Prior art> In addition to the integral foam molding method (see, for example, JP-A No. 59-49947) and the tension molding method (see, for example, JP-A-62-111721), soft pads can be formed using skin materials. There is a method of simultaneously thermocompression molding a urethane slab and a thermoplastic resin (hereinafter referred to as slab compression molding method). Compared to integral foam molding, this slab compression molding method has the advantage of reducing the number of steps and producing products at a lower cost.Compared to stretch molding, this method has a greater degree of freedom in shape and produces products with a more slender feel. It has the advantage of being able to manufacture

To explain this slab compression molding method in more detail, the slush molding method ("Production Terminology Dictionary" Toyota Engineering Society 1985
(Refer to 2010, p. 417, and JP-A-61-162328) PVC is formed into a skin on the surface of the mold, and a urethane slab as a foam layer and a thermoplastic resin as a base material are set thereon. and skin mold (slush mold)
In this method, a soft pad is obtained by clamping the pad with a compression mold and then molding them by thermocompression.

In the conventional slab compression molding method, in order to simultaneously thermocompress the skin material, urethane slab, and thermoplastic resin as the base material, it is necessary to heat the skin mold and compression mold simultaneously to the molding temperature and adjust the temperature.

<Unsolved Problems to be Solved by the Invention> In particular, for skin molds, the temperature must be adjusted with the semi-molten skin material attached immediately after slush molding.9 If the temperature becomes too high, the skin may flow or deteriorate due to heat. However, if the temperature is too low, thermocompression bonding with the urethane slab will be insufficient. Therefore, extremely careful temperature control was required, but
It was extremely difficult to maintain the temperature of the skin mold within the optimum range while controlling the temperature of the compression mold. In addition, when using a fluidized bed furnace or hot air oven to heat up the skin mold, the temperature must be controlled by the time it is left to stand after molding the skin, and it may be affected by the outside temperature or the molding temperature of the skin may be restricted. Sometimes I received it.

As described above, there were extremely difficult problems in skin-type temperature control.

Another problem is that the urethane slab is completely compressed and pushed into the skin mold, so the semi-molten skin material is subjected to strong pressure and is pulled by the urethane slab, causing damage to the skin material. There was a problem. The pressure and drag from the slab that the skin material receives becomes worse when molding products with large irregularities, so
The degree of freedom in the shape of the product to be molded had to be small a<.

The present invention was made in order to solve the problems of the above-mentioned difficulty in controlling the temperature of molds and damage to the skin material caused by the strong pressure and pulling of urethane slabs. To provide a method for molding a soft band that allows easy temperature control and does not apply destructive force to the skin material.

<Means for Solving the Problem> The method of molding the soft band of the present invention that can achieve the above-mentioned purpose involves preforming a preform body in which a urethane slab serving as a foam layer and a thermoplastic resin serving as a base material are crimped together. The preform is then placed in a slush mold to which a semi-molten skin material, which becomes the skin, is attached, and the skin material and the preform are bonded and molded by thermocompression.

When manufacturing a preform body, it is possible to use a separately manufactured preforming mold of an appropriate shape, but the skin mold (slush molding mold) and compression mold used in the conventional slab compression molding method can be used to manufacture the preform body. It can be used as is. Specifically, a urethane slab and a thermoplastic resin are set in a slush molding die that does not have a skin material formed on the surface, and then the slab and thermoplastic resin are heated by clamping the mold with a compression mold. All you need to do is press it, and in case 7, at least the compression mold needs to be heated.

In order to ensure that the preform body has a degree of freedom in shape to the extent that undercut processing is possible during preforming, the thickness of the foam layer of the preform body is controlled to, for example, the thickness of the foam layer of the molded product + 40 m. It is essential to do so.

Compression mold (
There is no need to heat or adjust the temperature of the mold on the base material side.

<Function> In the molding method of the present invention, thermocompression bonding of a thermoplastic resin as a base material and a urethane slab as a foam layer, and thermocompression bonding of the urethane slab and a semi-molten skin material as a skin, are performed.
Although they are performed separately, this makes it possible to heat and adjust the temperature of the skin mold and compression mold at different times, making it easier to control the temperature of the mold.

Furthermore, since the skin material is not thermocompression bonded to a preform body having a shape similar to the skin material, the pressure and drag that the skin material receives from the slab is reduced.

As a result of the above, it is possible to make it difficult to cause damage to the skin (piercing through the urethane slab).

<Example> An example of the soft pad molding method of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

Example 1 First, as shown in FIG. 1, a skin mold 1 (slash molding mold/electroforming mold) for manufacturing an instrument panel pad was
Density 20 breast/m3. A urethane slab 2 (manufactured by Prigiston, trade name: "Everlight") with a raw thickness of 35 mm and a plate-shaped thermoplastic resin 3 serving as a base material heated to 190° C. are set. The resin 3 is made of 9-plate polypropylene containing reinforcing fibers (manufactured by Mikuni Seisakusho, product name: "
-・Ipavia”). The skin mold 1 was not heated and was kept at approximately the same temperature as room temperature (about 20° C.).

Next VC As shown in Figure 2, a compression mold 4 with the necessary clearance for the skin mold 1 is heated to 210°C, and the original mold 4 is heated to 210°C.
The thermoplastic resin 3 and the urethane slab 2 are thermocompression molded by clamping the molds with the skin mold 1 and the skin mold 1. After mold clamping 1
After curing for 20 seconds, cooling to below 60°C and demolding, the urethane slab 2 recovers to an extent of 60% due to compression restoring force as shown in Fig. 3, forming a preform product 5 of intermediate shape with a thickness of 15 to 25I+Ill. is obtained. −, epidermal type 1
The skin material 6 is manufactured by slush molding using the following method. As shown in Figure 4, the skin mold 1 was heated to about 200C.
Powdered vinyl chloride 6& is put there, held for about 10 seconds, and the skin mold is turned over as shown in Figure 5 to remove the excess vinyl chloride 6a, leaving the skin mold 1 in a semi-molten state. A skin material 6 having a thickness of 0.8 mm is obtained.

Subsequently, as shown in FIG. 6, mold clamping is performed to compress the preform 5 with the skin mold 1 (temperature: 200° C.) to which the skin material 6 remains attached and the compression mold 4. The compression mold 4 was used to manufacture the preform product 5 and then left to cool down, and its temperature was 20 to 60°C. After curing the preform 5 in a compressed state for 300 seconds,
After cooling to .degree. C. and demolding, a soft pad with a foam layer thickness of 4 m is obtained.

Example 2 The operation was almost the same as in Example 1, but when manufacturing the preform product, instead of the skin type, 90.5-5
m Use a preforming mold with a large cavity. In this case, in order to suppress the recovery of the thickness of the foam layer of the preform product due to the large cavity size, the preforming mold is
Heat to 80-210°C.

In this example, since a suitably designed preforming mold is used without using a skin mold, - a preform product that cannot be obtained in the shape of the mold can be placed in a shell in a shape closer to the desired shape. Embodiment 1 is also effective as a measure to prevent damage to the epidermis.

Comparative Example A soft pad was manufactured by a conventional slab compression molding method in which a skin, a urethane slab, and a thermoplastic resin as a base material were simultaneously bonded under heat, and the failure rate was investigated. The following table shows the results compared with those of the above embodiment.

Test Example The simple-shaped soft pad shown in Figure 5 (in the figure, 12 represents the foam layer, 13 represents the base material, and 14 represents the skin) was coated with urethane slabs of various thicknesses (densities of 20 to 47 m).
3), and investigated the relationship between the compressibility of the urethane slab and the breakage of the skin (the rupture υ caused by the urethane slab) in the cases of manufacturing using the method of the present invention and the conventional method. . As a result, in the conventional method, if the urethane slab is compressed below the surface, the skin will be damaged, but in the manufacturing method using the preform of the present invention,
No damage to the epidermis was observed even when compressed to 12.5.

The above shows that according to the method of the present invention, a product having a foam layer with a higher density can be obtained.

<Effects of the Invention> As is clear from the above explanation, according to the soft pad molding method of the present invention, a urethane slab serving as a foam layer and a thermoplastic resin serving as a base material are preformed, and they are pressed together. By making a preform and pressing it against the skin in the slush mold, simultaneous temperature control of the skin mold and compression mold is no longer necessary, making it easier to control the temperature of the mold, and it also maintains a semi-molten state. The pressure of the urethane slab on the epidermis is weakened, and the drag is also reduced.

As a result, it has become possible to significantly reduce the occurrence of skin damage during pad molding. This also makes it possible to manufacture products with a foam layer with a higher density or with larger irregularities without any problems.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of a preforming process according to an embodiment of the soft pad molding method of the present invention, and FIG. 3 is a sectional view showing a preform product obtained in the above preforming process. Figures 4 and 5 are explanatory diagrams of the slush molding process of the skin material, Figure 6 is an explanatory diagram of the thermocompression molding method of the preform product and the skin material according to one example, and Figure 7 is an explanatory diagram of the slush molding process of the skin material. FIG. 3 is a sectional view showing a soft pad. In the figure, 1... Skin mold (slash mold) 2...
... Urethane slab 3 ... Thermoplastic resin 4 ... Compression mold 5 ... Preform product 6 ... Skin material

Claims (1)

[Claims] By preforming, a preform body is produced in which a urethane slab that will become a foam layer and a thermoplastic resin that will be a base material are crimped together, and then the preform body is placed in a slush mold to which a semi-molten skin material that will become a skin is attached. A method for forming a soft pad, which comprises setting the above-mentioned skin material and a preform body by thermocompression bonding.