JPH048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for integrally molding a composite molded article. More specifically, the present invention relates to a resin press molding method for integrally molding a covering cloth material and a thermoplastic resin.

(Prior art) In recent years, molded products made of thermoplastic resins such as polypropylene have been used as base materials for interior parts such as automobile door trims, pillars, and glove boxes due to changes in design and ease of molding.
In order to give the molded product a luxurious appearance and a soft touch, a sheet-like composite material made by laminating woven or knitted cloth and synthetic resin foam is attached to the surface of the molded product as a covering material. Many combined interior parts are used.

Conventionally, methods for manufacturing such composite molded products include (1) manufacturing a molded product in a predetermined shape in advance by injection molding using a thermoplastic resin molding material;
(2) A method of manufacturing a product by applying an adhesive to the surface of the molded product along the shape of the molded product, and pasting the covering material so that the fabric on the coated surface is exposed to the surface; (2) the covering material; (3) The so-called injection insert molding method, in which the mold is set in advance in the mold of an injection molding machine, the mold is then closed, and molten resin is injected to produce a molded product having a surface material on the surface; (3) extrusion molding method; A method is known in which a three-layer composite sheet in which the obtained sheet and the above-mentioned surface material are laminated is integrally formed into a molded product of a predetermined shape by vacuum forming, pressure forming, or sheet stamping. There is.

(Problems to be Solved by the Invention) Method (1) is preferable because high pressure and temperature are not applied to the covering material itself, so the feeling of the covering material is hardly lost. product is obtained.

However, this method relies heavily on manual labor such as applying adhesive and attaching surface materials, and requires many steps to complete the product.
It is not suitable for mass production and has problems such as high production costs.

(2) Integral molding using the injection insert molding method uses high pressure of the plasticized resin during injection molding (usually
300Kgf/cm ² or more), the foam layer of the covering material that comes into direct contact with the plasticized resin may be crushed or torn, resulting in a loss of necessary cushioning properties. However, this method has the disadvantage that the cloth surface becomes fluffy and wrinkled, which significantly impairs the appearance of the obtained molded product.

Method (3) has a low molding pressure of 6 kgf/cm ² or less, and can be molded at a relatively low temperature near the softening point of the raw material resin for the sheet.
It is suitable for integral molding of large thin parts because there is less hair falling on the cloth surface of the covering material and less collapse of the foam layer.

However, with this method, it is impossible to integrally mold molded products with ribs and bosses, molded products with partially different wall thicknesses, and molded products with complex shapes with undercuts. Since the shape of the material is sheet-like as described above, an extra portion (blank) remains after molding, which becomes a molding loss and causes a reduction in material yield. Furthermore, it takes time to reheat the three-layer laminated sheet, and a large amount of power is consumed for the reheating, resulting in many problems in terms of productivity and economy.

The present inventors have conducted extensive research to solve the above-mentioned problems in integral molding of composite molded products. As a result, a method of press-molding under specific molding conditions a covering material in which a synthetic resin foam layer is attached to the back side of a fabric with naps on one side and a thermoplastic resin base resin has been developed, which solves the above-mentioned problems. We have discovered that this is a molding method that solves all of these problems, and have completed the present invention.

As is clear from the above description, an object of the present invention is to provide a molded article having the above-mentioned covering material on the surface,
An integrated composite molded product that can be produced in large quantities and at low cost, with complex shapes without falling hair or wrinkles on the cloth surface of the covering material of the molded product, and without crushing or tearing the foam layer. An object of the present invention is to provide a molding method.

(Means for solving problems) The present invention has the following configuration.

(1) A sheet-like facing material formed by pasting a foamed elastic layer made of synthetic resin on the back side of a fabric with naps on one side is placed on the molding surface of the upper die of a resin press molding machine that has been opened in advance. Place it so that it is in contact with the ground, and within the molding surface area of the lower mold that faces the upper mold,
After placing a required amount of thermoplastic resin base material layer in a plasticized state, both molds are closed and the sheet-like facing material and base material layer are integrally molded by the mold clamping pressure. Keep the temperature below 10℃ and the temperature of the lower mold between 10 and 25℃, and weigh 100Kg within 1 second.
Apply pressure to a mold clamping pressure of f/cm ² and increase the mold clamping pressure to 5 to 30 kgf/cm 1 to 5 seconds after reaching the above pressure.
A method for integrally molding a composite molded product, characterized by reducing the pressure to less than cm ² and holding it for 10 to 60 seconds.

Examples of the thermoplastic resin constituting the base layer used in the present invention include crystalline polypropylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, and crystalline propylene-ethylene containing 70% by weight or more of a propylene component. Examples include polymers, acrylonitrile-butadiene-styrene copolymers (ABS resins), polyamide resins, polystyrene resins, etc. In particular, from the viewpoint of moldability, low specific gravity is achieved by using crystalline polypropylene and propylene components of 70% by weight. It is effective to use a polypropylene resin containing the above-mentioned crystalline propylene-ethylene copolymer. The above synthetic resins may include talc, mica, glass fibers, synthetic fibers (polyester fibers, polyamide fibers, rayon fibers, etc.), natural fibers (cotton fibers, acetate fibers, hemp fibers, etc.), carbon fibers, and wood. Organic fillers such as flour and rice hulls can be added.

There is no particular restriction on the fabric having naps on one side used in the present invention, and fabrics that give a feel and feel of luxury are preferred. In particular, fabrics made of synthetic fibers such as polyester fibers, polyamide fibers, and polyacrylonitrile fibers that are tricot knitted and have raised or piled surfaces are preferred. In addition to these fabrics, woolen fabrics, nonwoven fabrics, synthetic leather, etc. can also be used.

The foamed elastic layer made of synthetic resin used in the present invention is foamed polypropylene, foamed polyurethane, foamed polyethylene, foamed polyvinyl chloride, etc.
An example of this is a flexible foam sheet that is 10 to 30 times thicker. In particular, when the thermoplastic resin used for the base layer is a polypropylene resin, the adhesiveness and foam elasticity between the base layer and the foam elastic layer can be exemplified. From the viewpoint of maintaining the elasticity of the layer, it is preferable to use a foamed polypropylene sheet with an expansion ratio of 15 to 30 times and a wall thickness of 2 to 5 mm.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

FIG. 1 is an elevational view of the main parts of a resin press molding apparatus showing a process in the middle of molding when the present invention is practiced. In Figure 1, 1 is the upper mold, 2 is the lower mold,
3 indicates a resin pouring nozzle. Inside the upper mold 1 and the lower mold 2, cooling water supplied by separate mold temperature controllers (not shown) is circulated, and the surface 1a of the upper mold 1 is preferably 10°C or lower. 8℃
Thereafter, the surface 2a of the lower mold 2 is constantly maintained at a temperature of 25° C. or lower. Further, although not shown, the resin pouring nozzle 3 is connected to an extruder via a resin metering device and a passage, and autocharges the resin plasticized by the extruder directly onto the lower mold 2. It is equipped with a mechanism that can automatically move in and out of the lower mold 2 or move in two dimensions in conjunction with this resin charging operation.

Using a resin press molding device having the above configuration, first, the skin layer 5 of a tricot fabric made of polyester fiber and having a raised surface is formed.
A foamed polypropylene sheet 5b is adhered as a foamed elastic layer to the back side of the molded product 5b via an adhesive to prepare an integrally formed sheet-like facing material, and this is cut into an appropriate size larger than the projected dimension of the desired molded product. do,
It is attached to a predetermined position of the upper mold 1 which is waiting with its top and bottom open. At this time, the sheet-like facing material 5
As shown in FIG. 1, the fabric skin layer 5a side is placed upward in contact with the molding surface of the upper mold 1, and the method of fixing is by vacuum suction at the peripheral edge 1b of the upper mold 1, or by using clips or pins. Any suitable method such as stopping may be used.

After attaching the sheet-like facing material 5 to the upper mold 1,
The resin pouring nozzle 3 enters between the upper mold 1 and the lower mold 2 and pours out the base material layer 6 made of a thermoplastic resin such as polypropylene in a plasticized state while moving according to the shape of the molded product. By charging from the nozzle 3, the base material layer 6 is formed in the molding surface area of the lower mold 2.
is placed in the required amount. In this example, Chitsuso high crystalline polypropylene (melt flow rate: 22 g/10 mm), which has excellent heat resistance and rigidity, is used as the thermoplastic resin constituting the base material layer 6, and plasticization is performed by charging from the pouring nozzle 3. The temperature of the resin is 200±5℃
(compared to injection molding, etc.).

After the base material layer 6 is placed on the lower mold 2, the resin pouring nozzle 3 is moved out of the mold, and the upper mold 1 and the lower mold 2 are immediately closed to perform mold clamping, as shown in FIG. Pressure mold. When the base material layer resin is polypropylene, the molding conditions for conventional injection molding or press molding are: mold temperature at 30℃ or higher, resin temperature at 230℃.
℃ or higher and a mold clamping pressure of 100 kg/cm ² or higher is considered to be the general setting standard, but under these conditions, a fabric having a raised surface as used in the present invention is used as the skin layer 5a and plasticized. When integral molding with synthetic resin is carried out, as already mentioned, the problem is that it is affected by high pressure and temperature, which not only causes the fabric to fall and wrinkle, but also significantly impairs the appearance of the molded product. The foamed elastic layer 5b is crushed and loses its soft feel, resulting in an unsuitable product.

Therefore, in the integral molding method of the present invention,
A molding method was adopted in which the three conditions of mold temperature, mold clamping pressure, and pressure increase rate during mold clamping were simultaneously controlled within a specific range as specific conditions.

That is, the first condition of the integral molding method of the present invention is to set the mold temperature. The contacting surface 2a of the lower mold 2 is 25
Set below ℃.

The lower the temperature of the upper mold surface 1a, the more effective it is in maintaining the appearance of the fabric skin layer 5a and maintaining the elasticity of the foamed elastic layer 5b after molding. Since it is necessary to install a conditioning machine and special consideration must be given to preventing freezing of the cooling water, it is practically desirable to set the temperature to 4°C or higher. When the temperature of the upper mold surface 1a is set to such a low temperature, water droplets or a water film adhere to the entire surface of the upper mold surface 1a because the temperature is usually below the dew point temperature of the air around the molding machine.
Therefore, while the mold clamping is being performed, the skin layer 5a
When the fabric comes into close contact with the upper mold surface 1a, the surface of the fabric is moistened with water droplets or a water film, and this wetting phenomenon promotes cooling of the fabric, which further increases the foam layer 5b. Also, the temperature rise is prevented, which effectively acts in the direction of cooling and hardening, and contributes to the fabric appearance of the skin layer 5a after molding and the elasticity retention of the foam layer 5b. However, if the temperature of the upper mold surface 1a is 11
When the temperature exceeds ~12°C, the fibers of the skin layer 5a after molding start to fall and the texture of the fabric becomes coarse (the texture of the fabric opens and becomes crater-like), and the elasticity of the foamed elastic layer 5b becomes noticeably lowered, resulting in a change in the appearance of the fabric. becomes damaged. For this reason, it is desirable that the upper limit temperature of the upper mold surface 1a be 10°C or less, preferably 8°C, considering the margin. On the other hand, the lower the temperature of the lower mold surface 2a, the better the cooling effect, which contributes not only to maintaining the appearance and elasticity but also to shortening the molding time. Mold surface 2
Since the base material layer 6 in contact with a is subjected to flow resistance and shapeability is hindered, an appropriate temperature range is 15 to 25
℃ is preferable.

The second condition of the integral molding method of the present invention is to control the mold clamping pressure by reducing the pressure at the start of mold clamping to 100%.
A high pressure of about Kg/ ^cm2 is applied, and after reaching that pressure, 1~
After 5 seconds, the mold clamping pressure is reduced to 5 to 30 kg/cm ² and maintained. Even if the mold temperature is set to a low temperature as mentioned above, if the mold clamping pressure is kept high and pressurized,
Due to the strong compressive force, the hairs of the skin layer 5a fall and the foamed elastic layer 5b collapses, resulting in poor appearance.On the other hand, if the mold is clamped at low pressure from the beginning, the resin of the base material layer 6 will be spread out within the mold. Due to insufficient force, the base material layer 6
becomes defective. to solve this problem,
In order to shape the base material layer 6 in the mold into a predetermined shape and size, high pressure is required during mold clamping, but after the shaping is completed, the pressure is maintained as required to cool and stabilize the base material layer 6. Based on the idea that it would be sufficient to apply a low mold clamping force to perform In parallel with the above conditions, it is necessary to rapidly apply pressure to the base material layer 6 in order to quickly shape the base material layer 6 at the start of mold clamping. As condition 3, the pressure increase rate during mold clamping is 100Kg/cm ² within 1 second.
I decided to pressurize it so that

After integral molding under the above molding conditions, the upper mold 1 and the lower mold 2 are opened and the molded product given a predetermined shape is taken out. The time required to maintain pressure varies depending on the molding thickness of the base material layer 6, but
Appropriate times are 20 seconds for 1.5 mm and 30 seconds for 2 mm.

The thus obtained molded product has a fabric skin layer 5a with a good appearance without falling hair or wrinkles on the surface, and an elastic layer made of foamed polypropylene that has sufficient elasticity and is adhered to the back surface of the fabric skin layer 5a. 5b and a highly rigid polypropylene base layer 6 are firmly joined and integrally molded to form a composite molded product with a three-layer structure.

(Effects of the Invention) The integral molding method of the present invention does not require the complicated process of manually attaching a covering material such as cloth to a resin molded product as in the past. Since it is possible to obtain a cloth-covered molded product in a desired shape through a simplified process, it is possible to improve manufacturing workability and reduce costs. Ribs and undercut shapes are also formed on the outside of the layer, giving the fabric a luxurious appearance and a good texture and soft feel, making it suitable for use as high-class automotive interior parts.

[Brief explanation of drawings]

1 and 2 are process diagrams of a resin press molding apparatus used in the integral molding method of the present invention,
FIG. 1 is an elevational view of the main parts showing the state in which the facing material and base material are placed on the mold before mold clamping, and FIG. 2 is a sectional view showing the state during mold clamping. In the figure, 1 is the upper mold, 2 is the lower mold, 3
5 represents a resin pouring nozzle, 5 represents a covering material, 5a represents a fabric skin layer, 5b represents a foamed elastic layer, and 6 represents a base material layer.

Claims (1)

[Claims] 1. A sheet-like facing material formed by pasting a foamed elastic layer made of synthetic resin on the back side of a fabric with naps on one side is placed on the molding surface of the upper die of a resin press molding machine that has been opened in advance. Place it so that it touches
After placing the required amount of thermoplastic resin base material layer in a plasticized state within the molding surface area of the lower mold that faces the upper mold, both molds are closed and the sheet-like facing material and the base material are bonded together by the mold clamping pressure. A method of integrally molding the material layers, in which the temperature of the upper mold is kept below 10℃, the temperature of the lower mold is maintained between 10 and 25℃, and a mold clamping pressure of 100Kgf/cm ² is achieved within 1 second. Pressure is applied, and 1 to 5 seconds after reaching the above pressure, the mold clamping pressure is reduced to 5 to 30 Kgf/cm ² or less and 10 to 60
A method for integrally molding a composite molded product, which is characterized by being held for seconds.