JPH0583055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing a multilayer molded product comprising a skin material and a core resin.

<Prior art> Multilayer molded products made of a skin material and a core resin are economical and lightweight, and can provide molded products with good formability and excellent surface properties such as decorativeness and soft feel. Because of this, they are used in large quantities in all kinds of fields, including automobiles and home appliances.

As a method for manufacturing these multilayer molded products, for example, as proposed in Japanese Patent Application Laid-open No. 59-150740, a sliding opening is movably attached to a female mold or a male mold, and the male mold slides through. After sandwiching the periphery of the skin material between the skin material fixing frame and the female mold, molten resin is supplied between the skin material and the female mold or the male mold, and A method has been proposed in which molding is performed by closing a mold and a male mold.

<Problems to be solved by the invention> However, although it is possible to produce a multilayer molded product without wrinkles or tears in the skin material even in fairly complex molded products using conventional methods, problems may arise depending on the shape of the molded product, etc. There was a problem in that when the molten resin for the core material was supplied, excessive heat and stretching were applied to the skin material, causing it to lose its texture and cause tearing.

An object of the present invention is to provide a method for manufacturing a multilayer molded product having an excellent texture and consisting of a skin material and a core resin.

<Means for Solving the Problems> The present inventors have continued to conduct intensive studies on the production of multilayer molded products with excellent texture. As a result, when manufacturing a multilayer molded product consisting of a skin material and a core resin, the skin material is sufficiently squeezed and pre-shaped in the same molding machine, and the molten resin is poured into the mold before it is closed. The present inventors discovered that a multilayer molded product with an excellent texture of the skin material can be obtained by supplying the material, and the present invention was completed. That is, the present invention is a method for manufacturing a multilayer molded product 12 made of a skin material 8 and a core resin 11, which includes the following steps.

(a) First step of sandwiching the skin material 8 between the skin material fixing frame 4 and the female mold 3, which are movably attached to the male mold or the female mold (b) Cavity of the male mold 2 and the female mold 3 A second step (c) of pre-shaping the skin material 8 by moving the male mold 2 and/or the female mold 3 until the clearance becomes 5 times or less the thickness of the skin material. A third step of moving the male mold 2 and/or the female mold 3 until the cavity take-up clearance becomes larger than the second step and the cavity take-up clearance at the time of completion of shaping (d) Skin material 8 and the female mold 2 or the female mold A fourth step (e) in which molten resin 10 as a core material is supplied between the mold 2 and the mold 3; a fifth step in which molding is performed by closing the male mold 2 and female mold 3 until a predetermined cavity clearance is achieved; In the specification, the mold whose outermost side surface is the outer surface when the mold is closed is referred to as the male mold, and the mold which is the inner surface is referred to as the female mold.

The method of the present invention will be explained below based on the drawings. 1, 3-6 are longitudinal cross-sectional views of an apparatus illustrating the method of carrying out the invention. Figure 2 is the first
FIG. 3 is a plan view of the lower mold (male mold) and the skin material fixing frame taken along the line A-A' in the figure. In FIG. 2, the continuously supplied skin material is shown in perspective.

The mold device 1 consists of a male mold 2 located below, a skin material fixing frame 4, an expansion/contraction device 5, and a female mold 3 supported by a well-known elevating mechanism (not shown) and located above. The skin material fixing frame 4 has an upper surface facing the female mold 3, is attached to the male mold 2 side by a plurality of expansion and contraction devices 5 so as to be vertically movable, and has an opening through which the outer surface 6 of the male mold 2 can pass. . The expansion/contraction device 5 may be any known hydraulic cylinder, pneumatic cylinder, pneumatic spring, urethane spring, steel spring, etc. depending on the required stroke length and the like.

The method of the present invention is carried out as follows using the apparatus as described above.

First step: The skin material 8 is laid between the skin material fixing frame 4 and the female mold 3 (Fig. 1). Then, lower the female mold 3,
The skin material 8 is held between the skin material fixing frame 4 and the skin material fixing frame 4.

Second step: The molds are closed in a sandwiched state until the cavity clearance a of the male mold 2 and female mold 3 becomes 5 times or less the thickness of the skin material 8. Along with this, the peripheral edge 9 of the skin material 8 is sliding between the skin material fixing frame 4 and the female mold 3, and the skin material 8 is being stretched and squeezed into the recess of the female mold 3, so that the skin material 8 is sufficiently It is narrowed down and preshaped (Figure 3).

Third step: The female mold 3 is raised until the cavity take-off clearance a of the male mold 2 and the female mold 3 becomes larger than the cavity take-off clearance at the completion of the second step and shaping (FIG. 4).

Fourth step Between the skin material 8 and the male mold 2, molten resin 10 is passed through a resin passage (not shown) provided in the male mold 2.
supply.

Fifth step: By lowering the female mold 3 (Fig. 5) and closing both the female and male molds to the cavity clearance position upon completion of the prescribed shaping, the skin material 8 and the core resin 11 are Multilayer molded product 1 is completed when molding is completed as one unit.
2 is obtained (Figure 6). In the present invention, the supply of the molten resin 10 is not limited to the above-mentioned timing, but after the completion of narrowing and preliminary shaping of the skin material 8,
It is sufficient that the female mold 3 is raised and the cavity take-off clearance of the female and male molds is larger than the cavity take-back clearance at the time of completion of shaping, and the process may be carried out while raising the female mold 3 within this range. , it may be performed with a temporary stop. It may be further raised to a specific position and then supplied after it starts descending again.

In the present invention, a vacuum suction mechanism is provided in the mold on the side that the skin material 8 comes into contact with when the molding is completed, and vacuum suction is performed at an appropriate timing in the shaping process.
Supply of core material molten resin 10 and female. Molding may also be carried out by integral operation of mold closing by both male and female molds and the vacuum suction.

Furthermore, a pressurized air blowing mechanism is provided on the mold on the opposite side of the mold to which the skin material 8 comes into contact upon completion of molding.
Before supplying the molten resin 10 of the core material, pressurized air is supplied, and the male and female molds are closed and the skin material 8 is shaped to the final shape or close to the final shape by supplying the pressurized air. Then, the molten resin 10 may be supplied and molded until the mold closure is completed.

In addition, in all or part of the following steps, that is, the second step of squeezing and preshaping the skin material 8, the fourth step of supplying the molten resin 10, and the fifth step of performing mold closing molding. , the clamping force of the skin material 8 between the skin material fixing frame 4 and the female mold 3 is
It is prepared appropriately depending on the type of product and the shape of the product.

Further, the positional relationship between the male mold 2 and the female mold 3 can be freely selected, and the skin material fixing frame 4 can be attached to either the male mold 2 side or the female mold 3 side.

As the core resin used in this invention, any resin commonly used in compression molding, injection molding, and extrusion molding can be used, such as polypropylene, polyethylene, polystyrene, acrylonitrile-styrene-butadiene block copolymer, Thermoplastic resins such as nylon, non-foamable or foamable resins such as thermoplastic elastomers such as ethylene-propylene block copolymers, styrene-butadiene block copolymers, and fillers such as inorganic fillers and glass fibers. ,
Those containing additives such as pigments, lubricants, and antistatic agents can be used.

The skin material used in this invention includes woven fabric,
Non-woven fabrics, metals, fibers, thermoplastic resin nets,
Examples include paper, metal foil, sheets or films of plastic resins and thermoplastic elastomers, and materials decorated with uneven patterns such as grains, printing, dyeing, etc., or foams may also be used. Furthermore, it is also possible to use these products alone or in the form of a laminate made by laminating two or more of them using an adhesive or the like. When using these skin materials, the entire surface or a portion thereof may be preheated prior to supply in order to adjust the tensile stress and elongation of the skin material.

<Effects of the Invention> In the present invention, while controlling the slip resistance of the skin material by holding the peripheral edge of the skin material with an appropriate force, the cavity clearance of both the male and female molds can be adjusted to 50% of the thickness of the skin material. The male and/or female molds are moved until the skin material is sufficiently squeezed and preformed, and then the cavity clearance of both molds is expanded to a state that is larger than the cavity clearance at the completion of molding. By supplying the molten resin of the core material between the skin material and the male or female mold while leaving a margin in the skin material, excessive heat and stretching are applied to the skin material when the molten resin is supplied. You can prevent deterioration of texture, tearing, etc.

With this method, it is possible to efficiently produce a multilayer molded product with excellent texture even if it has a fairly complex shape.

<Example 1> Polypropylene (Sumitomo Chemical Co., Ltd.) was used as the core material resin.
Sumitomo Noblen Co., Ltd. AY564), a 0.6 mm thick grained polyvinyl chloride sheet as the skin material,
Using a laminated product with a polypropylene foam sheet with a thickness of 3 mm and a foaming ratio of 15 times, a box-shaped molded product with a length of 300 mm, a width of 250 mm, and a height of 100 mm is molded under the following conditions using the method explained in Figures 1 to 6. did.

The molded product was free from tears and wrinkles, and had good grain retention.

Molding conditions: Resin temperature 200℃, mold temperature 35℃ Cavity clearance at the end of the second process 3.0
mm, cavity take-off clearance in the fourth process 50 mm,
Clearance at completion of molding: 3.0 mm <Comparative example> Except for Example 1, in which the second step was omitted and the cavity clearance was set at 50 mm, and the core material resin was supplied in the fourth step. Molding was carried out under the same conditions as in Example 1. The skin material of the molded product was torn at the corners, and a good molded product could not be obtained.

<Example 2> ABS resin (Sumitomo Nogataku Co., Ltd.) was used as the core material resin.
Clarastic Co., Ltd. MTH-2), as a skin material
Except that a polyester nonwoven fabric of 260gr/m ² and 1.5mm thickness was used, the resin temperature was 240℃, the cavity clearance at the end of the second process was 2.0mm, and the cavity clearance at the fourth process was 10mm. Example 1
It was molded under the same conditions. A good molded product was obtained with no tears, wrinkles, or resin seepage.

<Example 3> Polypropylene (Sumitomo Chemical Co., Ltd.) was used as the core material resin.
(Sumitomo Noblen AZ564), using a polyvinyl chloride sheet (thickness 0.5 mm) with woolly nylon lining on the back side as the skin material, the cavity clearance was 2.0 mm at the end of the second process, and the fourth process Molding was carried out under the same conditions as in Example 1, except that the cavity clearance at the time of molding was 15 mm, and the cavity clearance at the time of completion of shaping was 2.0 mm. A molded article with no tears or wrinkles and good grain retention was obtained.

[Brief explanation of the drawing]

1 to 6 are drawings for explaining the method of the present invention, and FIGS. 1 and 3 to 6 are sectional views of the device,
Figure 2 shows the lower mold (male mold) from line A-A' in Figure 1.
and a plan view of the skin material fixing frame. In FIG. 2, the continuously supplied skin material is shown in perspective. 1... Mold device, 2... Male mold, 3... Female mold, 4
... Skin material fixing frame, 5 ... Expanding device, 6 ... Outer surface of male mold, 7 ... Inner surface of female mold, 8 ... Skin material,
9... Periphery of skin material, 10... Molten resin, 11...
...Core resin part after molding, 12...Multilayer molded product.

Claims (1)

[Claims] 1. Skin material 8 and core resin 11 comprising the following steps:
A method for manufacturing a multilayer molded product 12 comprising: (a) First step of sandwiching the skin material 8 between the skin material fixing frame 4 and the female mold 3, which are movably attached to the male mold or the female mold (b) Cavity of the male mold 2 and the female mold 3 A second step (c) of pre-shaping the skin material 8 by moving the male mold 2 and/or the female mold 3 until the clearance becomes 5 times or less the thickness of the skin material. A third step of moving the male mold 2 and/or the female mold 3 until the cavity take-up clearance becomes larger than the second step and the cavity take-up clearance at the time of completion of shaping (d) Skin material 8 and the female mold 2 or the female mold A fourth step (e) of supplying molten resin 10 as a core material between the molds 3 and 3; and a fifth step of molding by closing the male mold 2 and female mold 3 until a predetermined cavity clearance is achieved.