JP3196340B2 - Molding method of multilayer molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for efficiently producing a multilayer molded product in which a skin material is integrally bonded to a resin surface.

[0002]

2. Description of the Related Art Conventionally, various attempts have been made to attach a skin material to the surface of a resin molded product in order to impart a soft touch or a high-grade touch to the surface thereof. For example, a resin molded product body that is a core material layer is manufactured by a method such as injection molding, and a skin material separately preformed by a thermoforming method or the like is bonded with an adhesive, and a preformed core material layer is formed. A method in which a skin layer is set in a mold, urethane is injected and foamed during this time to obtain a multilayer molded article having a foamed intermediate layer,
A method of disposing a skin material on an injection mold and injecting a molten resin by injection press-fitting, as disclosed in Japanese Patent Application Laid-Open No. 1-235613, supplying a skin material and a molten resin between unclosed molds,
A method of obtaining a multilayer molded product by cooling under pressure is known.

[0003]

Each of the above-mentioned methods for obtaining a multilayer molded article has its own problems. The methods of (1) and (2) increase the cost due to the number of steps. Since the injection molding in the method (1) is performed at a high pressure, the skin material is easily damaged by the pressure and heat during molding, and the skin material that can be actually used is extremely limited. On the other hand, in the method, since molding can be performed at a fraction of the pressure compared with the injection molding method, it is necessary to produce a multilayer molded product in which various skin materials are laminated without damaging the skin material during molding. This method is an excellent method, but in this method, when the molded product is deep drawn or has a complicated shape, there is a problem that the skin material hardly follows the molded product shape, and troubles such as tearing easily occur. . As a method for solving such a problem, it has been considered that a skin material previously shaped by thermoforming using a pre-shaping mold having the same size as the shaping mold is disposed in the shaping mold. If the shaping surface material does not fit the molding surface of the molding die due to the variation of the molding conditions at the time of pre-shaping, or if the skin material is pre-formed with one pre-shaping die, the skin material Since the shrinkage differs depending on the type of the mold, the shaped skin material does not match the molding surface of the molding die. In addition, there is a problem that it takes time and labor to accurately position and fix a separately formed shaped skin material on a molding die molding surface, thereby increasing the number of molding steps and increasing costs.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have arrived at the present invention. That is, the present invention supplies a skin material and a thermoplastic resin in a molten state between the unclosed male and female molds, molds, cools, and forms a multilayer molded product in which the skin material is bonded to the surface of the molded product. A method for forming a multilayer molded product, comprising the following steps: (1) A first step in which a preheated panel (1) on which a preheated skin material (6) is placed is opposed to an upper or lower mold, (2)
Preheating panel (1) and outer periphery of molding surface of upper or lower mold (7)
To form an enclosed space by abutting through the skin material periphery,
A second vacuum suction is performed through a small hole (11) provided in the upper or lower mold to suction and adsorb the preheated skin material (6) to the upper or lower mold forming surface facing the skin material. Step (3) The preheating panel (1) is removed from between the upper and lower molds, and while the mold is closed or the mold closing is temporarily stopped, the preheated panel (1) is adsorbed from the resin passage (16) provided in the lower or upper mold. A third step of supplying a thermoplastic resin in a molten state between the skin material (6) and the lower or upper mold, and (4) a fourth step of further performing mold clamping to a final position, followed by pressurization and cooling.

As the thermoplastic resin used in the present invention, any resin can be used as long as it is a resin used in ordinary injection molding and extrusion molding. For example, polypropylene, polyethylene, polystyrene, acrylonitrile / butadiene / styrene copolymers can be used. Coalescence, nylon, polyvinyl chloride and the like.

Examples of the skin material used in the present invention include sheets and thermoplastic elastomer sheets made of various thermoplastic resins such as polyvinyl chloride, polystyrene, polypropylene, acrylonitrile / butadiene / styrene copolymer, and nylon. Leather-like sheet whose surface has been subjected to graining, or a laminated material of these sheets and woven fabric, knitted fabric, non-woven fabric, etc. Further, on the back side thereof, foamed polyethylene sheet, foamed polypropylene sheet, foamed polyurethane sheet, etc. And a laminated material obtained by laminating the above foam sheets.

Next, a detailed description will be given with reference to the drawings. 1 to 6 are schematic sectional views of an apparatus showing a molding step. The preheating panel (1) can place a preheated skin material on it and can be transferred to a molding die. The preheating panel (1) may be integrally formed with a heating source. It may be separable. In the former case, for example, the inside of the panel
By embedding the heater (1a) and forming the panel surface into various desired shapes such as a flat surface on which a skin material can be placed, a hemispherical shape, or the like, a preheating panel integrally formed with a heating source can be obtained. . In the latter case, a heater portion is provided detachably below the preheating panel having a desired shape, or a (far) infrared heater (1b) is provided above the preheating panel. Of course, these can be appropriately combined.
FIG. 1 shows a case where a heating integrated preheating panel in which an electric heater is embedded is further heated from above by an infrared heater. A large number of small holes (3) are provided on the upper surface of the preheating panel (1) on which the skin material is placed, and these are connected to a passage (4) in the panel. This passage (4) is connected to a vacuum line connected to a vacuum pump and a compressed air line connected to a compressor via a switching valve (5). By switching the switching valve (5), the skin material can be sucked through the small holes (3), and the mold release by compressed air can be performed. The skin material placed on the preheating panel is preheated, and when the skin material (6) reaches a temperature suitable for preforming, the preheating panel (1) is transferred between the upper and lower molds,
The skin material is opposed to the upper mold surface. Normally, the skin material is adsorbed and fixed to the preheating panel by vacuum suction from the small holes (3) while being placed on the preheating panel to prevent displacement or the like. In FIG. 2, the skin material is opposed to the mold surface of the upper mold. However, when the skin material is opposed to the mold surface of the lower mold, the skin material is vacuum-sucked from the small hole (3). Since the preheating panel is attracted and fixed to the preheating panel, the preheating panel can be turned upside down.

By lowering the upper die or raising the preheat panel, the preheat panel (1) is placed on the heat-resistant packing (9) attached to the outer periphery (7) of the molding surface of the upper die (6). (2) When they are brought into contact with each other via the peripheral edge, a closed space is formed between the preheating panel (1) and the upper mold forming surface (10) (FIG. 2). Here, the switching valve (5) is switched to supply compressed air from the small hole (3) through the passage (4), and at the same time, a large number of small holes (11) provided in the upper mold forming surface (10).
When the vacuum pump (13) connecting the connected passage (12) is operated, the skin material (6) is sucked and absorbed by the upper mold forming surface (10). At this time, since the periphery of the skin material is fixed by the contact between the outer periphery (7) of the molding surface of the upper mold and the preheating panel (1), the skin material is adsorbed to the molding surface of the upper mold while extending. (FIG. 3). The elongation of the skin material varies depending on the type, shape, and preheating temperature of the skin material, but it can be extended up to about two to three times as compared with that before heating, but any elongation rate is required. Since it is expected in advance in relation to the surface area of the preheated panel with respect to the surface area of the final molded product, it is necessary to select a skin material that sufficiently satisfies the elongation rate. In transferring and adsorbing the preheated skin material to the mold forming surface, a grain pattern can be transferred to the skin material by previously forming a pattern such as a grain on the mold forming surface. When the transfer of the skin material to the mold forming surface and the suction are completed, the preheating panel (1) is retracted from the space between the molds and returned to the original position (FIG. 4), and if necessary, for the next molding. Preheat the skin material.

On the other hand, an upper mold (8) is mounted on an upper platen (not shown) of a press which is driven up and down by hydraulic pressure, and is mounted on a fixed lower platen of the press by hydraulic operation. It is driven toward (14) to perform mold clamping. The upper mold to which the skin material is adsorbed is lowered, and when a suitable clearance is formed between the upper mold and the lower mold forming surface, a required amount of molten resin is supplied from a resin passage in the lower mold. FIG. 5 shows the upper mold forming surface (10) and the lower mold forming surface (1).
5) When the clearance is about 10 mm, the skin material (6) to which the molten resin (18) is adsorbed from the molten resin supply device (17) through the resin passage (16) provided in the lower mold (14). ) And the lower mold forming surface (15). After the adsorption of the skin material to the upper mold is completed,
Before the molten resin is supplied, for example, the outer periphery of the skin material can be cut into a predetermined shape by appropriate cutting means provided on the outer peripheral surface of the upper mold. Irrespective of the presence or absence of the above-mentioned trimming, forcible cooling by means such as blowing air onto the adsorbed skin material is effective in improving the appearance of the obtained multilayer molded product.

When the upper mold (8) is further lowered after the supply of the molten resin, the molten resin (18) flows to the end in the space between the skin material (6) and the lower mold forming surface (15), and the end is formed. (FIG. 6). Here, after pressurized and cooled for a predetermined time, the upper mold is raised to take out the target multilayer molded product.

Next, another example will be described. In the above example, since the outer periphery of the female mold forming surface for adsorbing the skin material is on the same plane and is a concave mold, only a flat preheating panel (1) is brought into contact with this tip, A closed space was formed between the female mold forming surface (10) and the preheating panel (1), and the skin material could be adsorbed. As shown in FIG. 7, when the mold forming surface protrudes from the outer periphery of the molding surface of the upper mold to which the preheating panel comes into contact, or when the outer periphery of the molding surface is not in the same plane, a flat preheating panel is used. Outer surface of upper mold (7)
And the closed space is not formed. The molding method in such a case will be described with reference to FIGS.

What is newly provided in FIGS. 7 to 9 is a frame (19) slidable up and down along an outer peripheral side surface of the upper mold forming surface via an expansion / contraction device (20). Frame (1
The lower end of the entire outer periphery of 9) is on the same plane, and a heat-resistant packing (9) is attached to the end thereof. Telescopic device (20)
, A spring, an air cylinder, a hydraulic cylinder or the like can be used.

As in the previous example, the preheated panel (1) on which the preheated skin material is placed is transferred between the upper and lower molds, and the skin material is opposed to the upper mold surface. When the upper mold is lowered or the preheating panel is raised, the frame (1) is extended by the expansion and contraction device (20).
The lower end of 9) is brought into contact with the preheating panel (1) through the heat-resistant packing (9) and the periphery of the skin material (6), and is closed by the preheating panel (1), the upper mold forming surface, and the frame (19). A space is formed. Thereafter, in the same manner as described above, compressed air is supplied from the switching valve (5) of the preheating panel and, at the same time, vacuum is suctioned from the small hole (11) of the upper mold to adsorb and fix the skin material to the male mold forming surface. (FIG. 7).

Thereafter, molding is performed in the same manner as described above. FIG. 9 shows the final mold clamping position, in which the expansion and contraction device (20) is smaller than the clamping force and further contracted, and the frame (19) is almost completely embedded in the upper mold.

[0015] The molding method of the present invention is a heat compression molding method, and has a basic feature that the molding pressure is as low as several times lower than the injection molding method and the skin material is not easily damaged during molding. Nevertheless, even with such a pressure depending on the kind of the skin material and the like, the appearance may be easily damaged by the pressure and heat during molding. In order to prevent this, the supply of the molten resin is stopped when the clearance between the upper and lower mold forming surfaces is between (C + 0.1) and (C + 100) mm, or the mold clamping speed is set to 30 mm / sec.
It is better to set it to c or less. Here, C means the clearance between the upper and lower mold forming surfaces (10, 15) at the final mold clamping position.

The preheating panel (1) is heated mainly by heat conduction from a heating source, such as an integral type with a heating source, or a heater portion detachably provided below the preheating panel. In such a case, it is usually made of a metal such as iron, copper, or aluminum. However, when the heating source is radiant heat such as (far) infrared light, even a material having a low thermal conductivity such as ceramics is used. The material may be any material as long as it is heat-resistant, but the surface is preferably smooth so that the placed skin material can contact uniformly. Also,
In preheating the skin material, the entire surface of the skin material may be heated so as to be uniform at the same temperature, or the temperature of the skin material may be partially changed by providing a temperature distribution on the preheating panel, so that the temperature of the skin material is reduced. You may adjust the elongation of the skin material at the time of adsorption,
This is appropriately performed depending on the type of the skin material, the shape of the molded product, and the like.

The small holes (3) provided in the preheating panel (1) are as follows:
Usually, its cross-section is circular, but it is not specified in any way for its purpose. If the diameter of the small hole (the maximum width if it is not circular) is too large, the adsorption power will be large, but the small hole mark will remain on the surface of the laminated synthetic product, so that the mark is small enough to leave no trace. Holes need to be provided. The size of the small holes depends on the type of the skin material and the molding conditions, but is usually selected in the range of 0.05 to 3 mm in diameter. The number and arrangement of the small holes are appropriately set so that the skin material does not fall from the preheating panel (1) or displace during the suction. The small hole portion is usually provided by perforating the preheating panel, but if necessary, a thin tube of ceramics, stainless steel, or the like may be embedded and fitted into the small hole of the panel surface portion or all of the small hole if necessary. . This is the same for the small holes (11) in the molding die. Incidentally, such small holes themselves are usually provided discontinuously when viewed from the panel surface, but may be in a groove shape having a groove width in the above range in some cases. As a method in this case, a groove may be provided directly on the preheating panel, or heat-resistant blocks may be arranged such that the gap is within the above range.

The present invention relates to a molding method in which a preheated skin material is adsorbed on a molding surface of a mold, and then a molten resin is supplied and bonded. This is to perform the pasting composite type with the same mold.

[0019]

According to the present invention, it is possible to efficiently obtain a multilayer molded product in which a skin material is integrally bonded to a surface of a core molded product having a deep drawing or a complicated shape. These can be used as suitable for vehicle parts and light electric equipment parts. In particular, it is suitable for manufacturing automobile interior parts such as instrument pads.

[0020]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 A multilayer molded product was manufactured by the apparatus and method shown in FIGS. As a preheating panel (1), an electric heater (1) is internally provided.
a) was incorporated, and a heating source integrated type having a smooth surface was used. The panel plane is 20x30cm and diameter 1
12mm holes are provided, and the temperature of the
Adjusted to 5 ° C. As a skin material, a 0.7 mm thick vinyl chloride sheet (manufactured by Kyowa Leather Co., Ltd.), which is grained on its surface and lined with an elastic cloth, is placed on a preheated panel with its grained surface facing up. To an infrared heater (1
b) Also heated from 160 ° C on the embossed surface and 165 ° C on the back surface
(FIG. 1). After preheating, the preheated panel was transferred between the upper and lower dies of the molding die, and the skin material was opposed to the upper die. Immediately, as shown in FIG. 2, the preheating panel is brought into contact with the outer periphery of the molding surface of the upper mold via the periphery of the skin material to form a closed space, and the vacuum suction from the small holes (3) of the preheating panel is stopped. Send compressed air, and at the same time
Vacuum suction was performed from 1). The skin material having a fixed peripheral edge was transferred and adsorbed to the upper mold forming surface while being stretched along the upper mold forming surface (10) by compressed air from below and vacuum suction from above. (FIG. 3). After the skin material is adsorbed on the molding surface of the upper mold, the sending of the compressed air from the preheating panel is stopped, and the preheating panel is retracted from between the upper and lower molds to the original position (FIG. 4), and the upper mold is lowered. Was. When the upper and lower mold surface clearances become 10 to 7 mm, while lowering the upper mold at a mold closing speed of 8 mm / sec, Sumitomo Noblen BPZ5077 melted at 210 ° C. as a molding resin (Sumitomo Chemical Industries, Ltd.) Talc 15% polypropylene, melt flow index 40 g / 10 min) is supplied from the resin passage of the lower mold (FIG. 5), and finally the clearance between the upper and lower mold molding surfaces is 2.5.
mm (Fig. 6). The upper and lower mold forming surface temperatures at this time were 50 ° C. and 40 ° C., respectively.
Obtained multilayer molded product (15cm x 25cm, depth 10c)
m) had a good appearance.

Example 2 A multilayer molded article having a complicated shape was manufactured by the molding apparatus and method shown in FIGS. In this example, the same skin material used in Example 1 was preheated in the same manner with a preheating panel having a size of 135 × 45 cm, and the frame provided on the outer periphery of the upper mold forming surface and the preheating panel were put through the periphery of the skin material. To form a closed space with the upper mold forming surface. Thereafter, molding was performed in the same manner as in Example 1. The obtained multilayer molded product (130 cm × 40 cm, maximum depth 30 cm) had a good appearance.

[0023]

[Brief description of the drawings]

FIG. 1 is a sectional view of an apparatus showing a molding step.

FIG. 2 is a cross-sectional view of the apparatus showing a molding step.

FIG. 3 is a sectional view of the apparatus showing a molding step.

FIG. 4 is a sectional view of the apparatus showing a molding step.

FIG. 5 is a sectional view of the apparatus showing a molding step.

FIG. 6 is a sectional view of the apparatus showing a molding step.

FIG. 7 is a cross-sectional view of the apparatus showing a molding step.

FIG. 8 is a sectional view of the apparatus showing a molding step.

FIG. 9 is a cross-sectional view of the apparatus showing a molding step.

[Explanation of symbols]

(1) Preheating panel (11) Small hole (1a) Heater (12) Passage (1b) Heater (13) Vacuum pump (3) Small hole (14) Lower die (4) Passage (15) Lower metal Molding surface (5) Switching valve (16) Resin passage (6) Skin material (17) Molten resin tank (7) Molding surface outer periphery (18) Molten resin (8) Upper mold (19) Frame (9) Heat resistance Packing (20) Telescopic device (10) Upper mold forming surface

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeo Kitayama 2- 10-1 Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Industries Co., Ltd. (72) Inventor Shigeyoshi Matsubara 2- 10-1 Tsukahara, Takatsuki-shi, Osaka Sumitomo (56) References JP-A-1-235613 (JP, A) JP-A-5-31742 (JP, A) JP-A-60-48350 (JP, A) JP-A-63-137816 (JP (JP, A) Japanese Utility Model Sho 61-22616 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 43/18-43/20 B29C 43/32-43/42 B29C 43 / 52,51 / 10,51 / 42 B29C 69/00-69/02

Claims (2)

(57) [Claims] 1. A method for supplying a skin material and a thermoplastic resin in a molten state between unclosed male and female molds, closing the mold, cooling, and forming a multilayer molded product having the skin material bonded to the resin surface. And a method for forming a multilayer molded product, comprising: (1) A first step in which a preheated panel (1) on which a preheated skin material (6) is placed is opposed to an upper or lower mold, (2)
Preheating panel (1) and outer periphery of molding surface of upper or lower mold (7)
To form an enclosed space by abutting through the skin material periphery,
A second vacuum suction is performed through a small hole (11) provided in the upper or lower mold to suction and adsorb the preheated skin material (6) to the upper or lower mold forming surface facing the skin material. Step (3) The preheating panel (1) is removed from between the upper and lower molds, and while the mold is closed or the mold closing is temporarily stopped, the preheated panel (1) is adsorbed from the resin passage (16) provided in the lower or upper mold. A third step of supplying a thermoplastic resin in a molten state between the skin material (6) and the lower or upper mold, and (4) a fourth step of further performing mold clamping to a final position, followed by pressurization and cooling. 2. A second step includes a step of providing a preheating panel (1) and a frame (19) slidable in a mold clamping direction provided on an outer periphery of a molding surface of an upper or lower mold via an expansion device (20). A closed space is formed by abutting through the peripheral edge of the skin material, and the preheated skin material (6) faces the skin material by vacuum suction from a small hole (11) provided in the upper or lower mold. 2. The method of molding a multilayer molded product according to claim 1, wherein the upper and lower mold surfaces are suctioned and adsorbed.