JPH0470132B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a multilayer molded article (hereinafter referred to as a multilayer molded article) consisting of a skin and a core resin.

Plastic molded products are used in large quantities in all fields including automobiles and home appliances due to their economic efficiency, freedom of shaping, and light weight. However, on the other hand, it has drawbacks such as being cheap, feeling cold, and being easily scratched, so there has been a strong demand for it to have decorative properties and a soft feel. In the past, various studies have been made to obtain compounds with functions that satisfy these demands, but it has been found that a single material that maintains free formability and strength while improving the surface properties of the above-mentioned drawbacks. It is also difficult to have
Currently, multilayer molded products that combine multiple materials with different functions are commonly used.

There are many known methods for producing these multilayer molded products, including, for example,
As proposed in No. 13859 and others, there is a method in which the skin material is preformed by means such as thermoforming, placed in a mold, and then core material resin is injected and integrated. However, this method requires a large number of work steps and devices, and each device and molding method has its own technical problems, so it takes a lot of labor and money to obtain the final product.

Another method, as proposed in Japanese Patent Publication No. 50-19132 and others, is to use a device that has a vacuum forming function and a core resin injection function in a single mold. Basically, it doesn't go beyond the former.

Furthermore, as a method to overcome the drawbacks of the above two methods, as proposed in Japanese Patent Application Laid-Open No. 53-63461,
Place the unpreformed skin material in the mold,
A method of integrating it with a core resin has been proposed. Although this method is economical, the tension can only be controlled in one direction and the tension cannot be controlled in other directions, so wrinkles occur and it is difficult to obtain a molded product with deep three-dimensional markings. There is a limit in that only simple shapes can be obtained.

In addition, in order to give a luxurious appearance to the multilayer molded product, improvements have been made by using woven fabric as the skin material, as disclosed in JP-A-56-105954 and others.
It has achieved certain effects. Such woven fabrics are designed to have high elongation under low stress, and in the case of molded products with deep drawings and complex shapes, such as automobile instrument panels and console boxes, they are prone to tearing. However, there are problems such as deterioration of the feel of certain parts of the molded product and exposure of the core material resin to the surface through the woven fabric. Furthermore, due to the elastic recovery after molding based on the stretching of the woven fabric during molding,
This has the problem of causing deformation such as warping in the molded product and leaving residual strain. All of these phenomena are thought to be caused by excessive elongation of the woven fabric in specific parts of the molded product, such as small circular arcs and protrusions.

As a result of various studies in order to eliminate the drawbacks of the conventional methods, the present inventors integrated a backing material with a lower elongation than the surface layer material into a surface layer material, thereby preventing excessive elongation of the surface layer material. By suppressing uneven elongation and performing narrowing and shaping by fixing the periphery of the composite skin material with a fixing force that matches the elongation of the backing material, the skin layer of the molded product is free from wrinkles and tears. The present invention has been completed based on the discovery that it is possible to produce a multilayer molded product extremely economically, giving a beautiful appearance and simplifying the working process.

That is, the present invention provides a molding device that is movably attached to the female mold or the male mold of a molding device consisting of a female mold and a male mold,
A composite skin material consisting of a surface material and a backing material whose elongation is smaller than that of the surface material is placed between the fixing plate and the female mold by a skin material fixing plate having an opening through which the male protrusion passes. After sandwiching the periphery, a core material molten resin is supplied between the skin material and the female mold or the male mold, the female mold and the male mold are closed, and the skin material is squeezed into the female mold to perform molding. The present invention provides a method for manufacturing a multilayer molded product comprising a skin and a core resin.

The present invention will be explained in more detail below with reference to the drawings showing specific examples of the apparatus used in the method of the present invention. 1A to 1D are cross-sectional views showing a specific example of a molding apparatus used in the method of the present invention, which comprises a female mold 1 and a male mold 2, which together form the molding apparatus. The female mold 1 is supported by a well-known moving mechanism (not shown), and has a recess 4 in the center of the side surface 3 facing the male mold, which corresponds to the outer shape of the molded product, and the male mold around the recess 4 It has a suction line 6 that opens on the mold facing surface 3 and communicates with the female mold back surface 5, and is equipped with pneumatic cylinders 7 at the upper and lower parts. A plurality of rods 10 are slidably housed in the pneumatic cylinder 7, the rods 10 substantially facing the male mold facing surface 3 of the female mold 1, and each having a skin fixing plate 9 having an opening 8 fixed to its tip. Ru. On the other hand, the male die 2 tightly passes through the supply hole 12 for injecting the core material molten resin 11 and the opening 8 of the fixing plate 9, and extends the convex portion 13 protruding into the female die recess 4 from the female die facing surface. Get ready for the 14th.

To carry out the method of the present invention using the apparatus, first, as shown in FIG.
A composite skin material 17 consisting of 6 is brought into contact with the male die facing surface 3 of the female die 1, and is held by suction through the suction line 6. Next, as shown in FIG. 1b, the rod 10 of the pneumatic cylinder 7 is moved toward the female mold, and the fixing plate
After the composite skin material 17 is clamped with a predetermined fixing force by the female die 1 and the female die 1, the suction is released. Next, when the moving mechanism is activated to move the female mold 1 forward, the composite skin material 17 is pressed as shown in FIG. The core material molten resin 11 is squeezed into the recess 4 of the female mold 1 while slipping between them, and finally, as shown in FIG. It is injected between the composite skin material 17 and the male mold 2, and the integration with the composite skin material 17 is completed at the same time as molding.

In the method of the present invention, the peripheral edge 18 of the composite skin material 17 needs to gradually move inward as the molding progresses, as shown in FIGS. This is especially important.
That is, the composite skin material 17 tends to deform into a shape that substantially follows the shape of the male mold 2 as the male mold 2 advances. If the fixing force by the fixing plate 9 is too small, the composite skin material will cause a large slip between the female mold 1 and the fixing plate 9, and the composite skin material will have an area larger than that required for shaping the molded product. It is supplied inside and causes wrinkles. On the other hand, if the fixing force is excessive, the composite skin material will not be able to withstand this tension and will be damaged. Furthermore, if the composite skin material is fixed at only two opposing sides of the skin material as described in JP-A No. 53-53461, the amount of composite skin material supplied to the female mold recess becomes unbalanced, resulting in molding. Although the occurrence of wrinkles cannot be prevented when the structure of the product is complex, this problem can be solved by fixing the periphery of the composite skin material as in this specific example. Therefore, by gripping the entire periphery of the composite skin material with optimal fixing force, it is possible to form a molded product without wrinkles or tears.

To set the fixing force when carrying out the method of the present invention, the material properties, i.e., the elongation of the composite skin material, or the structural properties, i.e., the gap between the male and female molds, the drawing ratio, the shape of each vertex and each side of the molded product, etc. Although it is necessary to select the optimum value based on the curvature, etc., 5 to 150 kg/cm ² is generally used per cross-sectional area of the fixed portion.

When setting the required area for the composite skin material, we first use the developed area of the molded product as a standard, and then reduce this in consideration of the elongation of the composite skin material, thereby designing to minimize trimming loss. However, the area must not be so small that the peripheral edge of the composite skin material will fall off once the male and female molds are closed, and the fixing force will disappear.

The surface material of the composite skin material used in the present invention includes woven fabric, non-woven fabric, sheet or film of metal foil, thermoplastic resin, and thermoplastic elastomer, and may also include uneven patterns such as grains, printing, dyeing, etc. It is also possible to use a material decorated with or a foam material. 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. On the other hand, the backing material for the composite skin material may be any material that has a lower elongation than the surface material and is capable of drawing and shaping, and may be arbitrarily selected from among the above-mentioned surface materials. Note that the surface material and the backing material are laminated and integrated using an adhesive or the like. When using these composite skin materials, preheating may be performed prior to supply in order to adjust the tensile stress and elongation of the skin material.

Furthermore, as the core material resin used in the present invention, any resin commonly used in extrusion molding, injection molding, and press molding can be used, such as polypropylene, polyethylene, polystyrene, acrylonitrile-styrene-butadiene block copolymer, etc. thermoplastic resins such as nylon, thermoplastic elastomers such as ethylene-propylene block copolymers and styrene-butadiene block copolymers, thermosetting resins such as epoxy resins and phenolic resins, various vulcanized synthetic rubbers, and
Non-foamable or foamable resins such as urethane for RIM molding, and those containing additives such as inorganic fillers, fillers such as glass fibers, pigments, lubricants, and antistatic agents can be used.

FIG. 2 is a sectional view showing another specific example of the molding apparatus used in the method of the present invention. In this specific example, the fixing plate 9 is attached to the male mold 2 so as to be able to move forward and backward via a plurality of rods 10 that protrude from the side surface of the male mold 2 toward the female mold and have a stopper 19 at the tip. It is constantly pressed in the direction of the female mold 1 by a compression spring 20 disposed between it and the fixed plate 9. An annular recess 21 is provided at the protruding position of the rod 10 on the side surface of the male mold 2 to accommodate the spring when contracted.

When carrying out the method of the present invention using the molding apparatus of this specific example, as shown in FIG.
After suctioning and holding, the female mold 1 is advanced,
After the fixing plate 9 is brought into contact with the composite skin material 17 to fix the composite skin material and the suction is released, the female mold is further advanced and molten resin is injected through the supply hole 12 to perform molding.

In this case, the fixing force of the skin material is determined by the spring constant of the compression spring 20, so instead of a single spring, a combination spring consisting of springs with different spring constants may be used depending on the purpose.

FIG. 3 is a cross-sectional view showing another specific example of the molding apparatus used in the method of the present invention, and this apparatus has almost the same structure as the molding apparatus shown in FIG.
A and an upper male mold 2a, which together form a molding device, and the female mold 1a has a skin material fixing plate 9 similar to the device shown in FIG.

To carry out the method of the present invention using the apparatus, first, as shown in FIG.
a Place it on the top mating surface. Next, the rod 10 of the pneumatic cylinder 7 is lowered to sandwich the composite skin material 17 between the lower surface of the fixing plate 9 and the upper surface of the female mold 1a. Next, the molten resin 11 is supplied onto the composite skin material 17 exposed in the opening 8 using a well-known melt-plasticizing means (not shown) such as an extruder. Furthermore, when the elevating mechanism is operated to lower the male mold 2a, the molten resin 11 flows and presses the upper surface of the composite skin material 17, and accordingly, the peripheral edge 18 of the composite skin material 17
is squeezed into the recess 4 of the female mold 1a while slipping between the fixing plate 9 and the upper surface of the female mold 1a, and finally the male and female molds 1a and 2a are brought together, and the composite skin material is formed simultaneously with the molding of the core material molten resin 11. 17 is performed.

As described above, according to the method of the present invention, a multilayer molded product having a good appearance without wrinkles or tears in the skin layer can be manufactured extremely economically through simple working steps. Further, according to the present invention, when the composite skin material is decorated with a grain pattern or the like, it is possible to effectively prevent distortion, disappearance, etc. of the decorative pattern caused by stretching.

The method of the present invention will be explained in more detail below using Examples and Comparative Examples.

Example A multilayer molded product was manufactured using the molding apparatus shown in FIG. First, the suction area of the composite skin material was attached to the female mold using adhesive tape to make it non-air permeable, and the peripheral edge of the composite skin material was held in the female mold by suction.
Then, the pneumatic cylinder was operated to move the fixing plate, and the area around the skin material was fixed at a pressure of 40 kg/cm ² . After the suction was released, both the male and female molds were closed, and molten resin at a resin temperature of 230°C was supplied from the supply hole between the skin material and the male mold to integrally mold the skin material and the core material. As a result, a multilayer molded product with a good appearance without wrinkles, tears, deterioration in texture, or warping was obtained. The materials used and the products obtained are as follows.

Composite skin material Surface material woven fabric made of polyethylene terephthalate/polyurethane brushed single tricot (elongation: 150% in wale direction, 530% in course direction)
℃) and a backing material made of polyethylene terephthalate single tricot (elongation: wale direction 40
%, 75% in the course direction) of ethylene-vinyl acetate emulsion (Sumikaflex, Sumitomo Chemical Co., Ltd.)
Co., Ltd.), adhesive lamination, thickness 1.5 mm, core resin melt flow index of 15 g/min (230
℃ / 2.16Kg load) Ethylene-propylene block copolymer (Sumitomo Noblen AY564, manufactured by Sumitomo Chemical Co., Ltd.) Molded product shape Box-shaped with length 160 mm x width 160 mm x height 70 mm x thickness 3 mm, each vertex and Comparative example in which the side forms an arc with a radius of 5 mm A multilayer molded product was produced in the same manner as in the example except that the woven fabric of the above example was used alone as the skin material.

In the obtained molded product, the core resin was found to be exposed at the apex and each side, and the side surfaces were warped.

[Brief explanation of the drawing]

FIGS. 1 a to d are schematic explanatory views showing a cross section when a multilayer molded product is produced by one specific example of the apparatus used in the method of the present invention, and FIGS. It is a schematic explanatory view showing the cross section of an example. The main symbols in the figure are as follows. 1,
1a: female mold, 2, 2a: male mold, 4: recess, 6: suction line, 8: opening, 9: fixing plate, 11: molten resin, 12: supply hole, 13: convex part, 15: surface material,
16: Backing material, 17: Composite skin material.

Claims (1)

[Scope of Claims] 1. A skin material fixing plate that is movably attached to the female die or the male die of a molding device consisting of a female die and a male die, and that has an opening through which the convex portion of the male die passes. After sandwiching the periphery of a composite skin material consisting of a surface material and a backing material whose elongation is smaller than that of the surface material between the surface material and the female mold, the core is inserted between the skin material and the female mold or the male mold. A method for producing a multilayer molded product made of a skin and a core resin, characterized by supplying a molten resin, closing the female mold and the male mold, squeezing the skin material into the female mold, and performing molding. 2. After sandwiching the periphery of the skin material between the fixing plate and the female mold, the female mold and the male mold are closed to squeeze the skin material into the female mold for pre-shaping, and then the skin material and the female mold or The manufacturing method according to item 1 above, wherein a core molten resin is supplied between the mold and the male mold, and injection molding is performed. 3. Fix the skin material to the surface facing the male mold around the female mold recess by a suction mechanism, and then move the skin material fixing plate that is movably attached to the female mold to connect the fixing plate and the female mold. The manufacturing method according to item 2 above, wherein the peripheral edge of the skin material is held between them. 4. The skin material is fixed to the surface facing the male mold around the female mold recess by a suction mechanism, and then the peripheral edge of the skin material is held between the female mold and a skin material fixing plate that is movably attached to the male mold. The manufacturing method according to item 2 above. 5 After sandwiching the periphery of the skin material between the fixing plate and the female mold, supply the core material molten resin between the skin material and the female mold or the male mold, and combine the female mold and the male mold. The manufacturing method according to item 1 above, wherein press molding is performed. 6 The peripheral edge of the skin material is held between the female mold and a skin material fixing plate movably attached to the female mold located below, and the core material molten resin is supplied to the upper surface of the skin material. Manufacturing method in Section 5. 7. The manufacturing method according to any one of items 1 to 6 above, wherein the means for pressing the skin material fixing plate into a female mold is a pneumatic cylinder mechanism or a hydraulic cylinder mechanism. 8. The manufacturing method according to any one of Items 1 to 6 above, wherein the means for pressing the skin material fixing plate into a female shape is a spring.