JPH07164487A - Manufacture of skin-integrated multilayer molded article - Google Patents

Abstract

PURPOSE:To obtain a skin-integrated multilayer molded article with reduced damage in a skin material by a method in which a shut off nozzle is used for a resin supply inlet, and its structure is so arranged that the resin flow makes an acute angle with the horizontal surface of a mold when a resin is injected with the nozzle opened. CONSTITUTION:A shut off nozzle which forms a resin supply inlet of a lower mold 1 has a structure in which the piston 3 end in a nozzle 2 is opened to the resin flow. The side of the open part of the piston 3 end makes an acute angle with the horizontal surface of the mold 1, and a resin is injected at an acute angle to the horizontal surface of the mold 1. The molten resin therefore does not hit the skin directly during injection to reduce the damage of the skin. This effect is remarkable when foamed polyolefin is used as a cushioning layer of the skin material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a skin-integrated multi-layer molded product, and more particularly to a method for producing a skin-integrated multi-layer molded product with little damage to the skin material during molding.

[0002]

2. Description of the Related Art Multi-layer molded products composed of a skin material and a core resin are excellent in economic efficiency and appearance, and have a soft feeling and a high-class feeling. Therefore, they are used in the fields of automobile interior materials and home appliances. It is beginning to be done. Conventionally, the method of manufacturing multi-layer molded products was to attach the skin material to the injection-molded core resin molded product with an adhesive, but recently molding the skin material and core resin in the same mold. Then, a method for obtaining a skin-integrated multi-layer molded article was started. As the skin-integrated multi-layer molding, for example, as disclosed in JP-A-1-235613, a skin material is attached, a molten resin is injected under a condition of a mold charge clearance within an appropriate range, and subsequently, mold clamping is performed to mold. A method of forming by reducing the skin damage by performing shaping and bonding at the same time can be mentioned.

[0003]

Recently, demands for softness, cost reduction, and recyclability have increased, and a softer cushion layer having a higher expansion ratio (especially 20 times or more) or a non-crosslinked cushion layer has been used. It is in the direction of using skin materials. However, in the conventional skin-injection injection compression molding method using the conventional gate structure mold, the high-temperature molten resin directly collides with the skin material at the time of injection, so the heat spreads the skin material,
Under the present circumstances, a skin material having a cushion layer with a high expansion ratio or a non-crosslinked cushion layer, which is damaged by rupture or blistering, has not reached a practical level.
In addition, if the mold charge clearance is set to a large value so that the molten resin does not directly collide with the skin material and then injection is performed, there is a problem that production efficiency deteriorates. The present invention has been made in view of the above circumstances, and provides a method for producing a skin-integrated multilayer molded article which has less damage to the skin material and has an excellent appearance.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, the molten resin does not directly contact the skin material by using a resin supply port having a specific shutoff nozzle. By injecting like, there is no damage such as fluffing, tearing, blister etc. on the skin material,
It has been found that a skin-integrated multilayer molded product having an excellent appearance can be efficiently obtained.

That is, according to the present invention, in the skin-integrated multilayer molding of the skin material and the core resin, when the shutoff nozzle is opened and the molten resin is injected, the flow direction of the resin becomes an acute angle with respect to the horizontal surface of the mold. A method for producing a skin-integrated multilayer molded article, which comprises using a resin supply port having a structure for injection into

The method of the present invention will be specifically described below. FIG. 1 is a sectional view of the resin supply port with the shut-off nozzle closed according to the present invention, and FIG. 2 shows an example of a sectional view of the resin supply port with the shut-off nozzle opened. Further, FIG. 3 is a cross-sectional view showing a state of a resin flow at the time of injection of a molten resin when the outer skin is installed in a state where the mold is opened in the integral skin injection compression molding. As can be seen from the drawing, by using a nozzle having a structure in which the piston tip portion of the shutoff nozzle is opened in the downstream direction of the flow of the supply resin, the molten resin is blocked by the piston of the shutoff nozzle during injection and It spreads around and can be supplied without directly colliding with the epidermis, and damage to the epidermis can be reduced. In addition, since the gate pin does not remain in the molded product using the resin supply port of the present invention, the step of folding (removing) the gate pin can be omitted, the product damage caused by folding is eliminated, and the quality of the product is further improved. For reference, FIG. 4 is a cross-sectional view of the resin supply port with the conventional shut-off nozzle closed, FIG. 5 is a cross-sectional view of the resin supply port with the conventional shut-off nozzle open, and FIG. 6 is the conventional resin. The state of the flow of the resin at the time of supplying the molten resin in the skin integral injection compression molding using the supply port is shown. Since the molten resin directly collides with the epidermis at the time of injection, the epidermis is significantly damaged and a pock is generated. In addition, since the gate pin remains on the product, a step of folding the gate pin is required, which causes a problem that the product is cracked when the gate pin is folded.

As the cushion layer of the skin material of the present invention,
Olefin resin foams, polyurethane foams and the like can be used, and among them, the present invention exerts a remarkable effect particularly on olefin resin foams. The olefin resin foam includes both crosslinked type and non-crosslinked type. As the olefin resin of the olefin resin foam, various kinds can be used, and a homopolymer of an olefin monomer having 2 to 8 carbon atoms, and 2 of these olefin monomers can be used.
It includes a copolymer of one or more kinds, or a copolymer of these olefin monomers and other comonomers (for example, vinyl acetate, maleic anhydride, etc.). Specifically, high density,
Medium density or low density polyethylene, polypropylene, polybutylene, propylene-ethylene random copolymer,
Examples thereof include propylene-α-olefin copolymer and impact-resistant polypropylene. Of these, a propylene homopolymer or a propylene-α-olefin (for example, ethylene, butene-1, hexene-1) copolymer is preferably used. The olefin resin may be used alone or in combination of two or more. Further, ethylene-propylene copolymer elastomer, ethylene-propylene-diene copolymer elastomer and the like can be mixed with the olefin resin, and the mixing amount thereof is generally 50% by weight.
The following are preferred. As a method for foaming the olefin resin, various conventionally known methods are adopted, and the expansion ratio of the foam is not particularly limited, but is preferably 5 to 50 times.

A skin layer can be laminated on one surface of the cushion layer to form a skin material, and a polyvinyl chloride sheet, a polyolefin-based thermoplastic elastomer, or the like can be used for the skin layer. When the skin layer is used, the appearance of the molded product is remarkably improved, but it may not be necessarily used depending on the application.

The core resin of the present invention includes olefin resins such as polyethylene and polypropylene, styrene resins,
Any thermoplastic resin such as polyester and polyamide can be used, and among them, an olefin resin is particularly preferably used. Examples of the olefin resin used as the core resin include propylene homopolymer, propylene-α-olefin random copolymer, and impact resistant polypropylene. The olefin resin used for the core resin may be used alone or in combination of two or more. Further, in order to improve impact resistance, an ethylene-propylene copolymer elastomer, an ethylene-propylene-diene copolymer elastomer, etc. may be mixed. Generally, the mixing ratio is preferably 50% by weight or less. If it exceeds 50% by weight, the mechanical properties, especially the rigidity will be deteriorated. Further, an inorganic filler or an organic filler may be mixed in order to improve rigidity. Talc, mica, silica, glass fiber, graphite, etc. are used as the inorganic filler, and wood powder, organic fiber, straw, chaff, peanut shell, etc. are used as the organic filler, and the mixing ratio is 60% by weight or less. Is preferred. If it exceeds 60% by weight, the impact resistance is significantly lowered.

The melt flow rate of the core resin used in the present invention (230 according to JIS K7210)
Measured at 2.16 kg at ℃. (Hereinafter abbreviated as MFR) is 1 g /
10 minutes or more is preferable. If it is less than 1 g / 10 minutes, the supply rate of the molten resin becomes slow, the molding rate is lowered, and the appearance of the product is deteriorated, which is not preferable.

The shut-off nozzle of the present invention is, for example, a nozzle having the structure shown in FIG. 1, and the tip of the piston in the nozzle has a structure that opens in the direction of the flow of the supplied resin. The angle between the side surface of the open end of the piston in the nozzle and the horizontal surface of the mold is an acute angle, and the resin is injected at an acute angle to the horizontal surface of the mold. It is 85 ° or less, preferably 45 ° or less, although it depends on the distance between the two. If the angle exceeds 85 °, the molten resin directly contacts the skin material, which is not preferable. In addition, the above-mentioned angle is such that the distance between the mold surface and the skin material is 500 mm.
Below, it is preferably used when it is preferably 10 to 500 mm. If the distance exceeds 500 mm, the unevenness of cooling of the injected resin is likely to occur, resulting in poor appearance of the molded product. Also, if the distance is less than 10 mm, the skin material is easily damaged by heat. The number, shape, size and the like of the resin supply port of the present invention can be appropriately set according to the shape of the molded product, and the above angle can also be appropriately set within the above range.

In the present invention, the integral molding of the skin material and the core resin can be carried out by appropriately setting the conditions depending on the kind of the resin used, the shape of the molded product and the like. It is also possible to install a sheet made of another resin between the skin material and the core resin to obtain a multi-layer molded product. When supplying the molten resin for the core material, the resin supply port of the present invention is used. Can be used and molded.

[0013]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The skin material and the core resin used are shown below. (1) Skin material (1-1) A skin material obtained by laminating a polyvinyl chloride sheet on a polypropylene foam (PPF20030) having a foaming ratio of 20 times and a thickness of 3 mm. (1-2) A skin material obtained by laminating a polyvinyl chloride sheet on a polypropylene foam (Toray, PPF25030) having a foaming ratio of 25 times and a thickness of 3 mm. (1-3) A skin material obtained by laminating a polypropylene-based thermoplastic elastomer (Showa Denko KK, Oleflex TPO) on a polypropylene foam (Toray, PPF20030) having a foaming ratio of 25 times and a thickness of 3 mm. (1-4) A skin material obtained by laminating a polypropylene-based thermoplastic elastomer (Showa Denko KK, Oleflex TPO) on a non-crosslinked polypropylene foam having a foaming ratio of 10 times and a thickness of 3 mm.

(2) Core resin (2-1) Impact-resistant polypropylene having MFR of 50 g / 10 minutes.

The molding machine is MCM500 manufactured by Takahashi Seiki Seisakusho.
An injection compression molding machine was used. After setting the skin material between the molds with the mold open, the molten resin (resin temperature 200
(° C) is 50 m between the lower mold surface of the resin supply port and the skin material.
m, injection molding, compression molding, and cooling were performed to manufacture a skin-integrated multilayer molded article.

(Example 1) Using a resin supply port having the structure shown in FIG. 1, (1-1) was used as the skin material and (2) was used as the core resin.
-1) was used to perform injection compression molding with integral skin,
A skin-integrated multilayer molded product having no skin damage such as pockmarks, tears and blisters was obtained.

(Examples 2 to 4) As a skin material, (1-2),
As a result of molding in the same manner as in Example 1 except that (1-3) and (1-4) were used, there was no skin damage such as pocking, tearing, and blistering, and the adhesiveness between the core material and the skin material. A skin-integrated molded product having excellent properties was obtained.

(Comparative Examples 1 to 4) Skin integral injection compression molding was performed in the same manner as in Examples 1 to 4 using the conventional resin supply port having the structure shown in FIG. As a result, the skin material was torn due to the molten resin, and serious skin damage such as blistering occurred.

[0020]

As described above, according to the present invention, a skin material having a cushion layer having a high expansion ratio (especially 20 times or more) and a non-crosslinked cushion layer can be used, and it is excellent in softness and high-grade feeling, and It is possible to efficiently manufacture an inexpensive multi-layer molded product integrated with a skin, and it can be effectively used as an automobile interior material, a home appliance exterior material, and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a resin supply port with a shutoff nozzle of the present invention closed.

FIG. 2 is a cross-sectional view of the resin supply port with the shut-off nozzle of the present invention opened.

FIG. 3 is a sectional view of a compression molding machine at the time of injecting a molten resin of the present invention.

FIG. 4 is a cross-sectional view of a resin supply port with a conventional shut-off nozzle closed.

FIG. 5 is a cross-sectional view of a resin supply port with a conventional shut-off nozzle opened.

FIG. 6 is a cross-sectional view of a conventional compression molding machine during injection of molten resin.

[Explanation of symbols]

 1 Lower mold 2 Hot nozzle 3 Piston 4 Spring 5 Upper mold 6 Skin hold spring 7 Molten resin 8 Skin material

Claims (1)

[Claims] 1. In a skin-integrated multilayer molding of a skin material and a core resin, when a molten resin is injected by opening a shut-off nozzle, the resin is injected such that the flow direction of the resin is an acute angle with respect to the horizontal surface of the mold. A method for manufacturing a skin-integrated multilayer molded article, which comprises using a resin supply port having a structure.