JPH04325213A - Manufacture of multilayered molding - Google Patents

Abstract

PURPOSE:To manufacture a multilayered molding with a good appearance at a high cycle that has no creases and breakages in its skin material by securing a skin material on the upper mold or lower mold for molding through vacuum suction from the gap provided on the place corresponding to the non- product part of a multilayered molding in the upper mold or lower mold. CONSTITUTION:Between the not-yet-closed upper and lower molds 1, 2, a skin material 7 and molten thermoplastic resin 8 are supplied and then press-cooled so as to form a molding, at the same time, the molding surface is glued with the skin material 7. In this instance, a gap 5 is provided on the place corresponding to the non-product part of a multilayered molding in the upper mold 1 or lower mold 2. From this gap 5, the skin material 7 is secured and then molded on the upper mold 1 or lower mold 2 through the vacuum suction.

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 multilayer molded article in which various skin materials are bonded to the surface of a core layer made of thermoplastic resin.

0002

BACKGROUND OF THE INVENTION 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 cheapness, cold feel, and easy scratching, and there has been a strong demand for decoration and softness. 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. Therefore, at present, multilayer molded products that combine multiple materials with different functions are commonly used.

[0003] There are many known methods for producing these multi-layer molded products, for example, Japanese Patent Publication No. 50-19
In Publication No. 132, a female mold for injection molding is provided with many small holes, the sheet is drawn to the molding surface of the female mold by vacuum suction, molten resin is injected and press-fitted into the cavity, and the sheet is bonded and integrated with the molded product. A method is disclosed.

However, in this method, if the diameter of the small holes is increased in order to increase the suction force, small hole marks will remain on the surface of the skin material, which will impair the appearance of the product. In addition, in the method of increasing the suction force by providing many small holes with a small diameter,
Not only does this increase the cost of mold processing, but depending on the skin material, sufficient suction force may not be obtained.

Furthermore, Japanese Patent Application Laid-Open No. 53-63461 proposes a method in which an unpreformed skin material is placed in a mold and integrated with a core resin. 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 molded products with deep three-dimensional drawings.
There is a limit in that only relatively simple shapes can be obtained.

Furthermore, as proposed in Japanese Patent Publication No. 63-24807, the peripheral edge of the skin material is held between a skin material fixing frame and a female mold, and after the skin material is pre-shaped, a thermoplastic core material is formed. There is a method for manufacturing multilayer molded products in which resin is melted and supplied and molded, but it is not always possible to obtain satisfactory results for large molded products, especially when the shape is complex.

[0007]

[Problems to be Solved by the Invention] The present invention aims to eliminate the drawbacks of these conventional methods.In particular, for large multilayer molded products, the positioning of the skin material can be performed reliably and quickly, and the surface of the molded product can be An object of the present invention is to provide an extremely economical method for manufacturing a multilayer molded product that gives a skin material a good appearance without wrinkles or tears.

[0008]

[Means for Solving the Problems] As a result of intensive studies in view of the above problems, the present inventors have developed a multilayer molded product that has an extremely good appearance by carrying out compression molding while vacuum suctioning and holding the skin material. The present inventors have discovered that the following can be obtained and have completed the present invention. That is, the present invention supplies a skin material and a molten thermoplastic resin between upper and lower unclosed molds, cools them under pressure to shape a molded product, and simultaneously laminates the skin material to the surface of the molded product. The skin material is fixed to the upper mold or the lower mold by vacuum suction through a gap provided in the upper mold or the lower mold at a position corresponding to the non-product part of the multilayer molded product. This is a method for manufacturing a multilayer molded product.

[0009] The skin materials used in the present invention include woven fabrics, non-woven fabrics, fibers, thermoplastic resin nets, paper, metal foils lined with sheets so as to be vacuum suctionable, polyolefins, vinyl chloride, and nylon. Examples include sheets or films of thermoplastic resins such as, and thermoplastic elastomers such as polyolefin, polyester, urethane, and vinyl chloride. It is also possible to use these sheets or films alone or in a laminate of two or more types as the skin material. In order to create an even softer feel, a foam sheet made of polypropylene, polyethylene, urethane, etc. is laminated to the back of the skin material, or a foam sheet made of polypropylene, polyethylene, urethane, etc. is laminated to the back of the skin material, or a foam sheet is used to protect it from the heat of the molten resin during molding, or the skin material and core material layer are It is also possible to use a material with cloth or a sheet pasted on the back side for the purpose of strengthening adhesive strength. The skin material may be in sheet form as it is or may be pre-shaped by thermoforming or the like.

As the thermoplastic resin used as the core material layer in the present invention, any resin commonly used in compression molding, injection molding and extrusion molding can be used, such as polypropylene, polyethylene, polystyrene, acrylonitrile, etc. Examples include thermoplastic resins such as styrene-butadiene copolymers and nylon, and thermoplastic elastomers such as ethylene-propylene block copolymers and styrene-butadiene block copolymers. Moreover, those containing additives such as inorganic fillers, fillers such as glass fibers, pigments, lubricants, and antistatic agents can also be used as appropriate.

[0011] In the present invention, the skin material is fixed by vacuum suction through a gap provided at a predetermined position in the upper mold or the lower mold. This is the unused part of the multilayer molded product, that is, the non-product part. This non-product part is removed in post-processing after molding is completed.

[0012] In the present invention, since the skin material part that is vacuum-suctioned is a non-product part that is removed in post-processing after molding is completed, there is no problem even if gap marks are left on the skin material during molding, and the mold surface The suction force can be increased by increasing the gap provided between the two, and the skin material can be positioned and held quickly and reliably.

On the other hand, if the skin material to be vacuum-suctioned is a product part of a multilayer molded product, the back side of the vacuum-suctioned skin material will be in contact with the high-temperature molten resin, and moreover, it will not be pressurized by the press pressure. Due to this, gap marks are left on the surface of the skin material. In order to make this gap trace as inconspicuous as possible, the gap must be made as small as possible, but in order to obtain the necessary skin material retention force, the gap must be provided over almost the entire surface of the skin material. In such a case, there will also be gaps that are not sufficiently covered by the skin material, from which vacuum leaks will occur, making it even more difficult to obtain the necessary skin material retention force. Further, it is not preferable to provide a small gap over a wide surface of the mold because it requires a lot of effort in mold processing.

[0014] A gap is provided at a predetermined position of the upper or lower mold corresponding to the non-product part by inserting this part of the mold, making it into a split mold, or machining a small hole. be able to.

[0015] The molten resin in the present invention may be supplied by a molten resin supply device provided outside the mold.
More preferred is a method of supplying the resin through a resin passage provided in the upper or lower mold. In this case, the supply of molten resin is usually
The mold clamping speed is 30 mm/sec or less, and the upper and lower mold clearance is (C+5) to (C+100) mm (here, C
represents the clearance at the completion of imprinting). Furthermore, the mold is clamped until the clearance becomes Cmm, and the desired multilayer molded product is obtained by applying pressure and cooling for a predetermined period of time.

[0016]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 An example in which a mold for forming the molded product shown in FIG. 2 was attached to a press machine with a mold clamping force of 100 tons, and molding was performed using the molding apparatus shown in FIG. 1 will be described below. . In the lower mold (2),
A cylindrical inlet (4) is provided, and the inlet (4) and lower mold (2)
The gap (5) is 0.4 mm;
) vacuum suction of the skin material (7).

The skin material (7) is made of a textured vinyl chloride sheet lined with stretchable cloth and has a thickness of 0. 7m
Using m leather-like sheet (manufactured by Kyowa Leather Co., Ltd.),
As the thermoplastic resin, polypropylene (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen AX568, melt flow index 65 g/10 minutes) was used, and the upper mold (1
) and the lower mold (2) are set at 40°C and 50°C, respectively.

The skin material (7) is held by vacuum suction from the gap (5), the lower mold (2) is raised, and when the clearance between the upper mold surface and the lower mold surface is 8 mm, the lower mold (2) is lowered. The mold (2) stops rising, and the thermoplastic resin (8) is heated and melted at 200°C from the molten resin supply port into the mold through the resin passage (3) provided in the upper mold. Supply will begin. At this time, the vertical inner circumferential portion of the upper mold surface and the vertical outer peripheral portion of the lower mold surface slide, forming a cavity that is closed so that the molten resin (8) does not come out from there.

Immediately before the supply of molten resin (8) is completed,
When the lower mold (2) resumes its rise, the molten resin is pressurized and flows to the end of the cavity, filling the mold while pressing the skin material (7) against the lower mold surface.

[0021] The lower mold (2) is raised to the final mold clamping position, and after being pressurized and cooled for a predetermined time (40 seconds) in this state, the lower mold (2) is lowered to form the desired molded product. is taken out, and the non-product part (A) is removed with a punching blade to obtain the desired multilayer molded product covered with a skin material with a beautiful grain pattern.

Example 2 An example in which a mold for forming the molded product shown in FIG. 4 was attached to a press machine with a mold clamping force of 300 tons, and molding was performed using the molding apparatus shown in FIG. 3 will be described below. . In the upper mold (1),
Two cylindrical inserts (4) are provided, and the inserts (4) and the upper mold (
The gap (5) in 1) is 0.6 mm, and the skin material (7) is vacuum-suctioned through this gap (5).

[0023] The skin material has a thickness of 0. The back side of the 5mm grained PVC sheet has a thickness of 3mm. A 0mm foamed polypropylene sheet (manufactured by Toray Industries, Ltd., foaming ratio 15x) was laminated and pre-shaped by thermoforming to fit the inner surface of the upper mold (1), and the thermoplastic resin was , Polypropylene (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen AX568, Melt Flow Index
65 g/10 minutes), and set the temperatures of the upper mold (1) and lower mold (2) to 40°C and 30°C, respectively.

[0024] The pre-shaped skin material (7) is put into two pieces (
4) While holding the non-product part (A) by vacuum suction from the gap (5), lower the upper mold (1) until the clearance between the upper mold surface and the lower mold surface is 50 mm. At this time, the lowering of the upper mold is stopped, and the molten resin (8) obtained by heating and melting the thermoplastic resin at 190°C is poured into the mold from the three molten resin supply ports provided in the lower mold (2). Supply starts when the clearance is 20 mm, and completes supply when the clearance is 20 mm.

Furthermore, when the upper mold (1) is lowered, the molten resin (8) is pressurized and flows to the end of the cavity and into the mold while pressing the skin material (7) against the surface of the upper mold. Filled.

The upper mold (1) is lowered to the final mold clamping position, and after being pressurized and cooled for a predetermined time (40 seconds) in this state, the upper mold (1) is raised to form the desired molded product. is taken out, and the non-product part (A) is removed with a punching die to obtain a multilayer molded product having the desired soft feel and covered with a skin material with a beautiful grain pattern.

[0027]

According to the present invention, a large-sized multilayer molded product having a good appearance without wrinkles or tears in the skin material on the surface of the molded product can be manufactured economically in a high cycle. This can be widely used for vehicle interior parts, light electrical parts, etc.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an apparatus showing the molding method of the present invention.

FIG. 2 is a perspective view of a multilayer molded product molded in Example 1 of the present invention.

FIG. 3 is a longitudinal cross-sectional view of an apparatus illustrating the molding method of the present invention.

FIG. 4 is a perspective view of a multilayer molded product molded in Example 2 of the present invention.

[Explanation of symbols]

Claims (1)

[Claims] Claim 1: Supplying a skin material and a molten thermoplastic resin between upper and lower unclosed molds, cooling under pressure to shape a molded product, and at the same time bonding the skin material to the surface of the molded product. , a multilayer molded product characterized in that the skin material is fixed to the upper mold or lower mold by vacuum suction through a gap provided in the upper mold or the lower mold at a position corresponding to the non-product part of the multilayer molded product. Method of manufacturing molded products.