JPH0564837A - Molding method for multi-layer product - Google Patents

Abstract

PURPOSE:To constitute the title method so that air is not held between a skin layer and core material layer when the preshaped skin layer is fixed to a mold face, a thermoplastic resin sheet 16 is preheated, the core material layer is shaped by performing press molding and the same is stuck to the skin layer for integration. CONSTITUTION:A preshaped skin layer 6 is fixed to a mold surface, a preheated thermoplastic resin sheet 16 is fed onto a bottom force 14, after a gearing part has begun to engage, a space between the skin layer 6 and thermoplastic resin sheet 16 is deaerated through a small hole provided in the thermoplastic resin sheet 16 and molded integrally by sticking. With this construction, the skin layer 6 is stuck and molded without holding air between the skin layer 6 and core material layer and a multi-layer molded product can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a multi-layer molded article, and provides a multi-layer molded article containing no bubbles and having a good appearance.

[0002]

2. Description of the Related Art There is a method in which a thermoplastic resin sheet is preheated and pressed to shape it. In particular, in recent years, a method of preheating a thermoplastic resin sheet reinforced with long fibers and press-molding to obtain a reinforced molded product has become widespread. As the reinforcing fiber, glass fiber is most often used because it has a large reinforcing effect and is inexpensive and economically advantageous. Press-molded products of such glass fiber reinforced thermoplastic resin sheets have excellent physical properties such as rigidity and impact resistance because the fibers in the molded products are longer and have less orientation than injection-molded products reinforced with glass fibers. There are advantages such as being present and having little deformation. On the other hand, however, such a reinforced molded product has fibers near the surface and has poor gloss, and therefore it is desired to give the surface a decorative or soft feel.

As a method therefor, there is a method in which a skin layer preformed by thermoforming or the like and a core material layer obtained by press-molding a fiber-reinforced thermoplastic resin sheet are bonded with an adhesive. This method has many steps, is laborious, and is costly. It is also possible to stack the fiber reinforced thermoplastic resin sheet and the skin material on each other and press-mold them to form a laminated body.
In the case of a complicated shape, the skin material cannot follow the shape, and the outer skin material is likely to be broken, and wrinkles, wrinkles, and other external defects are likely to occur. In such a case, if the pre-shaped skin layer is fixed to the mold surface and the preheated fiber-reinforced thermoplastic resin sheet to be the core material layer is pressed and laminated to integrate, the above-mentioned problems are solved. .. However, at this time, since the pre-shaped skin layer has airtightness, there is a problem that air bubbles are trapped between the skin layer and the core layer of the multilayer molded product to impair the appearance. When a thermoplastic resin sheet containing no fiber is used for the core layer, the same problem of enclosing air bubbles occurs.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a preformed skin layer is fixed to a mold surface, and a thermoplastic resin sheet is preheated and pressure-cooled to form a core layer to form a skin layer. It is intended to prevent the air from being caught between the skin layer and the core material layer when it is attached.

[0005]

The inventors of the present invention have achieved the present invention as a result of extensive studies to solve the above problems. That is, the present invention, on one mold surface of the pair of upper and lower molds,
A pre-shaped skin layer is fixed, a preheated thermoplastic resin sheet is supplied onto the lower mold, pressure cooling is performed to shape the core material layer, and at the same time, the core layer is laminated and integrated to form a multilayer. In the method for obtaining a molded article, after the meshing portions of the upper and lower molds start to be closed, degassing is performed between the skin layer and the thermoplastic resin sheet through a small hole provided in the thermoplastic resin sheet to perform molding. It is a characteristic method for forming a multilayer molded article.

Examples of the thermoplastic resin sheet used in the core layer of the present invention include polypropylene sheets and polyethylene sheets. Typical examples suitable for carrying out the present invention are those having a large added value. A fiber reinforced thermoplastic resin sheet, especially a glass fiber reinforced thermoplastic resin sheet can be mentioned. As the glass fiber reinforced thermoplastic resin sheet, polypropylene, nylon or the like is used as a matrix resin, glass fibers having a medium fiber length of about 5 to 100 mm and powdered matrix resin are processed into a sheet shape by a wet papermaking method, or And a powdered resin is welded through a heating roll, or a matte product of long fiber glass is melted and laminated with a matrix resin to be impregnated into a sheet form.

The skin material used in the present invention is a thermoplastic resin sheet, particularly a thermoplastic resin sheet whose surface is embossed, printed, hot stamped, colored or the like, or a woven fabric or a non-woven fabric. A product lined with a resin sheet for airtightness so that it can be pre-shaped, and in order to obtain a soft feel, thermoplastic resin sheets, woven fabrics, non-woven fabrics, etc. are expanded polyethylene sheet, expanded polypropylene sheet, urethane foam It is also possible to use a sheet lined with a foamed thermoplastic resin sheet.

In order to bond and integrate these skin layers to the core material layer during press molding, the thermoplastic resin sheet (matrix resin in the case of the fiber reinforced thermoplastic resin sheet) to be the core material layer and the skin material It is advisable to select the thermoplastic resin sheet or the backing thermoplastic resin sheet as a resin material of the same quality having good heat-welding properties. For example, a combination of polypropylene core to the core material and a foamed polypropylene sheet to the skin material, a combination of polyethylene to the core material layer and a foamed polyethylene sheet to the skin material, a combination of vinyl chloride to the core material layer and a vinyl chloride sheet to the skin material,
Examples include a combination of ABS for the core material layer and ABS sheet for the skin material. If they are not homogeneous and do not weld, the core material layer resin and the resin sheet having good weldability may be attached to the back surface of the skin material by using an adhesive or the like.

The present invention will now be described in detail with reference to the drawings. 1 to 4 are schematic vertical cross-sectional views of an apparatus showing a molding process. In FIG. 1, (1) is a heating plate, in which a heater (2) is embedded, and the entire heating plate (1) is heated.
The heating plate (1) has a large number of small holes (3) on its surface, which are connected to the holes (4) and the switching valve (5). The switching valve (5) has a vacuum pump (not shown). It is connected and adsorbs the skin material (6) on the heating plate (1). In addition, when the switching valve (5) is switched, compressed air is sent instead of vacuum. (7) is another heating plate which has a built-in far-infrared heater, and heats the skin material (6) from the upper surface as well.

When the skin material (6) reaches a temperature suitable for preforming, the heating plate (1) is brought into contact with the upper mold (8). The upper mold (8) has a heat-resistant rubber material (9) for keeping airtightness, a small hole (10), and a hole (11) connected to this, and the hole end (12) is shown in the figure. Not connected to a vacuum pump. When the heating plate (1) is brought into contact with the upper mold (8) as shown in FIG. 2, the heating plate (1)
A closed space is formed between the upper mold and the upper mold (8). Hole end (1
When the vacuum pump connected to 2) is operated and at the same time the switching valve (5) is switched to send compressed air, the preheated skin material (6) is attracted to the upper mold surface (13), As shown in FIG. 2, the skin material (6) is preshaped and adsorbed on the upper mold surface (13).

The heating plate (1) is attached to the upper and lower molds (8, 1).
4) Except from between, place the thermoplastic resin sheet (16) preheated in an oven on the molding surface (15) of the lower mold (14). The thermoplastic resin sheet (16) has small holes (1
7) is provided. The small holes may be provided after preheating the resin sheet, or the small holes may be provided in advance and then the thermoplastic resin sheet may be preheated.

Although not shown, the upper die (8) is attached to the upper platen which is vertically driven by the hydraulic pressure of the press machine, and the lower die (14) is attached to the fixed lower platen. The lower mold (8) is provided with a nesting (18), and a space (19) and a hole (2
0), and a vacuum pump (not shown) is connected to the hole end (21).

Next, when the upper mold (8) is lowered and the upper and lower mold meshing parts (22, 23) slide through the preformed skin layer (6) and start closing as shown in FIG. , The descent speed is reduced or temporarily stopped, and the vacuum pump connected to the hole end (21) is operated. Thereby, the air between the skin layer (6) and the thermoplastic resin sheet (16) is small holes (17) provided in the thermoplastic resin sheet, grooves on the nest (18), the nest (18) and the lower mold. Gas is exhausted through the gap (24) between the (14), the space (19) below the nesting (18), and the hole (20) in sequence, and the thermoplastic resin sheet (16) and the lower mold surface (1).
Air during 5) is also exhausted at the same time.

Next, the upper mold (8) is lowered to the final position and pressure-cooled there for a predetermined time, and the thermoplastic resin sheet (16) is shaped into a core material layer and stuck to the skin layer (6). Are integrated. The upper mold (8) is raised to open the upper and lower molds (8, 14), and the desired multilayer molded product is taken out. The small holes provided in the thermoplastic resin sheet are sized so as to be blocked during molding. The appropriate size of the small holes varies depending on the thermoplastic resin sheet, its thickness, and the thickness of the molded product, but may be appropriately selected from the range of 5 to 30 mm in diameter. Since the obtained multilayer molded article is molded by degassing the air between the thermoplastic resin sheet which becomes the core material layer and the skin layer, it is possible to obtain a multilayer molded article with good appearance without inclusion of air bubbles.

In this example, the nest is provided at one place, but it is preferable to place it at a place where bubbles are easily generated. Further, the gap (24) is a gap that can be deaerated so that the thermoplastic resin sheet does not enter therein. Although this gap varies depending on the viscosity of the thermoplastic resin sheet, it is preferable to select an appropriate gap between 0.07 and 0.9 mm.

FIGS. 5 to 8 are schematic sectional views of devices showing another example. FIG. 5 shows the molding surface (13) of the upper mold in the same manner as the previous example.
The skin layer (6) is preformed and adsorbed and fixed on the lower surface of the lower mold (14), and the preheated thermoplastic resin sheet (16) is placed on the molding surface (15) of the lower mold (14). Activate the pin (2)
5) is moved upward and the thermoplastic resin sheet (16) is being pierced. The upper surface of the nest (18) is provided with a groove similar to the previous example. In this case, the nest (1
8) is urged upward by an expansion device (27) (a spring is used here) therebelow, and is at an upper limit position slightly higher than the surrounding molding surface (15).

Next, the upper mold (8) is lowered, and the meshing parts (22, 23) of the upper and lower molds start to close. FIG. 6 shows this state. The lowering speed of the upper mold (8) is reduced or temporarily stopped, and the vacuum pump at the hole end (21) is operated.

FIG. 7 is an enlarged view of the vicinity of the nest (18) in FIG. The air between the skin layer (6) and the thermoplastic resin sheet (16) is a pin (25) and the thermoplastic resin sheet (16).
Gap (30), groove on the upper surface of the insert (18), space (19) where the thermoplastic resin sheet (16) is slightly lifted by the insert (18), groove (28) provided on the molding surface of the lower mold. , Nesting hole (29), space (31), hole (2
0) are sequentially exhausted, and at the same time, the air between the thermoplastic resin sheet (16) and the lower die molding surface (15) is also exhausted.

Next, as shown in FIG. 8, the upper mold (8) is lowered to the final position and the mold is clamped. In the meantime, the telescopic device (27) goes to the mold clamping force, the nesting (18) is lowered to the lower limit position, its upper surface is at the same level as the molding surface (15), and the hole (29) is closed. Since the thermoplastic resin sheet of the groove (28) is carried away as a part of the core material layer, the suction force does not decrease even in the subsequent molding. Since the tip of the fork pin (25) is provided with a taper and a resin pressure is applied to the tip, the expansion device (26) shrinks to the resin pressure and the tip reaches the same level as the molding surface (15). Descend to. Here, when pressure cooling is performed for a predetermined time, the thermoplastic resin sheet (16) as shown in FIG.
Is shaped and cooled to form a core material layer, which is bonded to the skin layer to form a multilayer molded article.

The example of pre-forming the skin material on the mold surface has been described above. However, the skin layer formed by another pre-molding mold is fixed to the mold surface and similarly degassed and molded. Good.

Further, the preformed skin layer is fixed to the lower mold, a preheated thermoplastic resin sheet is supplied thereon, degassed from the upper mold, and similarly cooled under pressure. It is also possible to obtain a multilayer molded article.

[0022]

According to the present invention, a preformed skin layer is fixed to a mold, and when the core layer is press-molded from a preheated thermoplastic resin sheet, the skin layer is laminated to form a multilayer molded article. It is possible to obtain a molded product having no bubbles between the skin layer and the core material layer when molding the. These multilayer molded products can be used as suitable for vehicle parts, light electric equipment parts and the like.

[0023]

【Example】

Example 1 The apparatus and the molding method used were those shown in FIGS. As the skin material, a polypropylene sheet having a thickness of 0.5 mm and having wood grain printing was used, and the surface was preheated to 155 ° C. and pre-shaped on the upper mold surface. Next, a thermoplastic resin sheet (made by Cape La Sheet Co., Ltd.) reinforced with powdery polypropylene and glass fiber having a length of 12 mm and 30 wt% of glass fiber manufactured by a wet papermaking method and glass fiber having a thickness of 2.0 mm is manufactured at 210 ° C. When preheated, the glass fibers rise and expand to a thickness of about 6 mm. This is supplied to the lower mold, and after the meshing parts of the upper and lower molds start to close, the skin layer and the thermoplastic resin sheet are degassed through the small holes provided in the thermoplastic resin sheet and pressure cooled. And molded.
Molding was performed at upper and lower mold temperatures of 45 and 35 ° C., respectively. A multilayer molded product having a thickness of 4.5 mm, in which the thickness of the core material layer was twice the thickness of the glass fiber reinforced thermoplastic resin sheet before preheating, and without inclusion of air bubbles, and having a good appearance, was obtained.

Example 2 The apparatus and the molding method used were those shown in FIGS. As the skin material, a vinyl chloride sheet having a 0.5 mm thick vinyl chloride sheet having an embossed surface and a foamed polypropylene sheet (made by Toray Industries, Inc.) having a foaming ratio of 15 times and a thickness of 3 mm attached to the back surface is used. The surface was faced up so that the surface was 165 ° C. and the surface of the foamed polypropylene sheet was preheated to 135 ° C. and pre-shaped on the upper mold surface. The sheet of Example 1 was used as the thermoplastic resin sheet, preheated to 210 ° C. and supplied onto the lower mold, and a small hole was formed in the thermoplastic resin sheet by a pin that moves in the vertical direction by an expansion / contraction device. From the beginning of the closing of the meshing part, the space between the skin layer and the thermoplastic resin sheet was degassed through the small holes, and pressure cooling was performed for molding. Mold temperature at the upper and lower molds are 45 and 35 ℃,
The clearance between the upper and lower mold molding surfaces at the time of final mold clamping is 3.5.
Molded as mm. A multi-layer molded product having an excellent appearance with a soft feeling and without inclusion of air bubbles was obtained.

Comparative Example 1 The same as Example 1 except that the thermoplastic resin sheet reinforced with glass fibers was not provided with small holes, and was molded without degassing between the skin layer and the thermoplastic resin sheet reinforced with glass fibers. Molding was performed in the same manner. The obtained multi-layer molded product contained air bubbles.

[0026]

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a heating plate.

FIG. 2 is a vertical sectional view of an apparatus showing a molding process.

FIG. 3 is a vertical sectional view of an apparatus showing a molding process.

FIG. 4 is a vertical cross-sectional view of an apparatus showing a molding process.

FIG. 5 is a vertical cross-sectional view of an apparatus showing a molding process.

FIG. 6 is a vertical sectional view of an apparatus showing a molding process.

FIG. 7 is a partially enlarged vertical sectional view of the apparatus showing a molding step.

FIG. 8 is a vertical cross-sectional view of an apparatus showing a molding process.

[Explanation of symbols]

(1) Heating plate (2) Heater (3) Small hole (4) Hole (5) Switching valve (6) Skin material (7) Heating plate (8) Upper mold (9) Rubber material (10) Small hole ( 11) hole (12) hole end (13) upper mold surface (14) lower mold surface (15) lower mold surface (16) thermoplastic resin sheet (17) small hole (18) nesting (19) space (20) ) Hole (21) Hole end (22) Upper mold meshing part (23) Lower mold meshing part (24) Gap (25) Pin (26) Telescopic device (27) Spring (28) Groove (29) Hole (30) ) Gap (31) Space

Front page continuation (72) Inventor Takeo Kitayama 2-10-1 Tsukahara, Takatsuki City, Osaka Prefecture Sumitomo Chemical Co., Ltd. (72) Inventor Shigeyoshi Matsubara 2-10-1 Tsukahara City, Takatsuki City, Osaka Prefecture Industry Co., Ltd.

Claims (2)

[Claims] 1. A preformed skin layer is fixed to one mold surface of a pair of upper and lower molds, a preheated thermoplastic resin sheet is supplied onto a lower mold, and pressure-cooled. In the method of forming a core material layer and simultaneously laminating and integrating with the skin layer to obtain a multilayer molded article, the skin is passed through small holes provided in the thermoplastic resin sheet after the meshing portions of the upper and lower molds start to close. A method for molding a multilayer molded article, characterized by degassing between a layer and the thermoplastic resin sheet. 2. A pin that moves up and down by an expansion device is provided on a mold surface facing a mold to which a skin layer is fixed,
The method for molding a multilayer molded article according to claim 1, wherein the pin is provided with a small hole in the thermoplastic resin sheet.