JPS5983633A - Preparation of multiple molded product having decorative pattern - Google Patents

Abstract

PURPOSE:To obtain a multiple molded product having a decorative pattern faithfully transferred to the surface thereof, by a method wherein a laminate sheet containing a surface skin layer and a foamed layer is placed in a mold having a decorative pattern formed to the inner surface thereof and molten resin is injected into the mold. CONSTITUTION:A laminate sheet consisting of a surface skin layer 3 and a foamed layer 4 or these layers and a backing layer 6 is placed in a mold consisting of a female mold 1 and a male mold 2 having a decorative pattern formed to the inner surface thereof so as to be contacted with said decorative pattern. Subsequently, molten resin is injected into the mold. An embossed pattern 8 to be transferred to the surface of a molded product is provided to the inner surface of the female mold 1 by engraving. As the kind of the pattern, for example, a leather crepe pattern, a satin pattern or a hairline pattern are used. The surface skin layer 3 is integrated with the foamed layer by a painting, an adhering or a contact bonding means and the surface opposed to the unevenness of the inner surface of the female mold is made flat. As the material of the surface skin layer, thermoplastic resin, a thermoplastic elastomer or rubber can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a multi-layer molded product comprising a skin layer provided with a decorative pattern, a foam layer and a resin core layer.

Generally, it is widely practiced to add a grain pattern to the surface of a molded product in order to give a decorative effect to automobile interior parts and the like. A conceivable method for this is to obtain the final decorative product in a single step using the usual injection molding method, in which a decorative sheet-like material is placed in a mold and molten resin is injected under pressure to integrate the materials.

Such an economically advantageous one-step molding method makes it easy to add value to the product, and is expected to produce great industrial effects.

However, when carrying out the one-step molding using a sheet whose surface has been previously decorated by means such as an embossing roll, the desired decorative pattern cannot be maintained or reproduced with certainty.

The cause of this is that the irregularities on the surface of the decorative sheet are heated and compressed and deformed due to the high injection pressure and temperature.Furthermore, when the shape of the molded product becomes complex such as a curved surface, the irregularities on the surface due to the expansion of the sheet itself. It had a fundamental defect in that as the surface was stretched, the unevenness almost disappeared and only a distorted pattern was obtained. The inventor of the present invention has arrived at the present invention as a result of extensive research into a method for improving the above-mentioned drawbacks and faithfully transferring a decorative pattern onto the surface of a multi-layered molded product. That is, the present invention provides a laminated sheet consisting of a skin layer and a foam layer or these and a backing layer in a mold having a decorative pattern on the inner surface so that the skin layer comes into contact with the decorative pattern Iζ.
This is a method for producing a multi-layer molded product consisting of a skin layer having a decorative pattern, a foam layer and a resin core layer, which is characterized by placing the foam layer on the foam layer and then injecting molten resin behind the foam layer.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a cross-sectional m1 diagram of the laminated sheet used in the present invention. FIGS. 2 and 3 are cross-sectional views showing a state in which the laminated sheet is placed on the oval shape H and a state in which molten resin is injected behind the foam layer of the laminated sheet, respectively.

In FIGS. 2 and 3, 1 is a female mold, and 2 is a male mold. An uneven pattern 8 is engraved on the inner surface of the female mold to be transferred to the surface of the molded product.

Examples of the types of patterns used include leather grain patterns, satin texture patterns, hairline patterns, and the like. 3 is the skin layer, which is integrated with the foam layer by painting, adhesion, pressure bonding, etc.
The surface facing the unevenness on the inner surface of the female mold is made flat. The material of this skin layer [for example, polyvinyl chloride,
Polyethylene, polypropylene, polystyrene, ethylene-vinyl acetate copolymer, polyamide and other thermoplastic resins, thermoplastic elastomers, rubber films or sheets, etc. can be used. Furthermore, sheets impregnated with thermosetting resins such as epoxy, phenol, urea, and polyester, and room temperature vulcanizable rubbers such as silicone and EPDM can also be used by heating and curing them after the decorative pattern is formed. Furthermore, metal pieces such as aluminum and copper do not preclude application of the present invention. 4 is a foamed sheet which is compressed under high injection pressure during injection molding and transmits this pressure to the coating layer. The applied high pressure is combined with the heat conduction of the molten resin and the mold to plastically deform the skin layer along the unevenness of the female mold, thereby imparting a clear decorative pattern.

Furthermore, in the case of a complex shape such as a curved surface, the decorative pattern can be faithfully reproduced even if the skin layer is stretched. The material for the foam layer is
For example, it is possible to apply a backing sheet to polyvinyl chloride, polyester, foam, etc. to protect the foam layer, or to not apply a backing sheet to improve the adhesive strength due to the anchoring effect. The presence or absence and type of backing can be selected arbitrarily depending on the combination of the foam and resin core material and the purpose of improvement.The thickness of the skin layer and foam layer also depends on the application and performance, but the skin layer is 0. 1 to 3 mm, and a foam layer of 1 to 5 ms is preferably used.5
is the core material resin, and if it is a resin that can be injection molded, it is a thermoplastic resin, thermosetting resin, thermoplastic elastomer, rubber, or a material containing additives such as an inorganic filler, colorant, or lubricant. , regardless of type. Further, any ordinary injection molding machine can be used, regardless of whether it is a plunger type or a screw type. After the molded product obtained according to the present invention is removed from the mold, the cushioning property is maintained due to the elastic recovery of the foam layer, so it is suitable for interior materials such as automobile door rims, dash boards, console boxes, etc., and other textures. Suitable for this purpose.

The skin layer of Example 3 has a flat surface, a thickness i, and a vinyl acetate content of 2.
0% ethylene vinyl acetate copolymer sheet. The foam layer 4 is a urethane foam with a foaming ratio of about 30 times and a thickness of 5 mm, and 6 is a polypropylene sheet with a thickness of 1) at the back of the foam layer. Further, 7 is a 50μ ethylene vinyl acetate copolymer film. This laminated sheet, which has been bonded and integrated by hot press molding, is fixed with double-sided tape to the mating surfaces of a female mold with a leather grain pattern engraved on the inside of the mold and a male mold facing it. Molten polypropylene was injected from a closed injection nozzle and integrated. The leather grain pattern was clearly transferred to the surface of the molded product, and a molded product with a high-quality image and a soft touch feeling was obtained.

Comparative Example As a female mold, a mold in which no skin texture was carved on the inner surface was used. The laminated sheet is an ethylene vinyl acetate copolymer sheet/PP decorated with a skin grain pattern similar to the pattern of the female mold in the example using an emboss roll. It is similar to the one used. This stacked cocoon sheet was placed in a mold and injection molded in the same manner as in the example. The surface of the obtained molded article had almost no unevenness.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a laminated sheet used in the present invention. FIGS. 2 and 3 are cross-sectional views showing a state in which a laminated sheet is placed in a mold and a state in which molten resin is injected behind the laminated sheet, respectively. l...Female mold 2...Male mold 3...Skin layer 4...Foam sheet 5・・・・・・Core material resin 8・・・・・・Concave and convex pattern

Claims (1)

[Claims] A laminated sheet consisting of a skin layer and a foam layer or these and a backing layer is placed in a mold having a decorative pattern on the inner surface so that the skin layer is in contact with the decorative pattern, and then molten resin is injected into the mold. A method for manufacturing a multilayer molded product having a decorative pattern characterized by: