JPH06297489A - Manufacture of multilayer molded form - Google Patents

Abstract

(57) [Summary] [Structure] The skin material is supplied into a pair of unclosed male and female molds,
After that, the molten thermoplastic resin is supplied into the mold through a resin passage provided in the mold, both molds are clamped to shape the molten resin in the mold, and then pressure cooling is performed. In the method for producing a multilayer molded article in which a surface material is laminated on the surface of a thermoplastic resin core material, the temperature of supply of the molten thermoplastic resin into the molding die is 175 to 195 ° C., and the pressing surface at the time of completion of shaping. A multi-layer molded article characterized in that the pressure is 30 to 95 kg / cm @ 2, and after the shaping is completed, the product of the pressing surface pressure and the pressing time is in the range of 100 to 1500 kg / cm @ 2 .sec. Manufacturing method. [Effect] In a method for obtaining a multilayer molded article in which a skin material is preliminarily supplied between upper and lower molds, then a molten resin is supplied, the mold is closed and pressure is applied, and the skin material is bonded to the surface of the thermoplastic resin core material, It is possible to obtain a multi-layer molded product that maintains the surface appearance.

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 multi-layer molded article comprising a skin material and a thermoplastic resin core material used for automobile interior parts, household electric appliances and the like.

[0002]

2. Description of the Related Art Multilayer molded products composed of a skin material and a core layer of a thermoplastic resin are used in a large amount in various fields including automobile interior parts and household electric appliances due to their economical efficiency, light weight and good shapeability. It is used. In such a multilayer molded article, for example, as disclosed in JP-A-1-235613, a molten thermoplastic resin is supplied between a pair of male and female molding dies to which a skin material is supplied, and both dies are clamped. Then, the molten resin is shaped in a mold and, at the same time, a skin material is attached to the surface of the resin, and then the molten resin is cooled and solidified. However, in the conventionally known method,
The resulting multi-layer molded product may be deformed or the texture may be impaired, which greatly affects the productivity.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
As a result of earnest studies to produce a multi-layer molded product that maintains a good surface appearance, the inventors have controlled the temperature at which the molten thermoplastic resin is supplied into the mold and the pressure and pressure during molding. It was found that the object can be achieved by doing so, and the present invention was achieved.

[0004]

According to the present invention, a skin material is supplied into an unclosed pair of male and female molds, and then a molten thermoplastic resin is supplied into the molds through a resin passage provided in the molds. Then, both molds are clamped to shape the molten resin in the molds, and then pressure cooling is performed, and the skin material is pasted on the surface of the resin core material made of thermoplastic resin. In the manufacturing method of, the temperature of the molten thermoplastic resin supplied into the molding die is set to 17
5 to 195 ° C, 30 to 95 kg of surface pressure when shaping is completed
/ Cm2, and after completion of shaping, press-cooling is performed such that the product of the pressing surface pressure and the pressing time is in the range of 100 to 1500 kg / cm2.sec. To do.

The thermoplastic resin used in the present invention is not particularly limited as long as it is generally used in injection molding, compression molding, extrusion molding and the like, and various thermoplastic resins can be used. Is preferably used. Such a thermoplastic resin may be used alone, or may be blended with an inorganic filler such as talc, glass fiber, calcium carbonate, and, of course, a commonly used stabilizer, an additive such as a pigment is appropriately added. It may be blended. When a polypropylene resin is used as the thermoplastic resin, a polypropylene resin or a polypropylene resin composition having a melt flow index (MI) at 230 ° C. of 15 to 200 g / 10 minutes is preferably used.

The skin material in the present invention is not particularly limited,
Various materials are used. Examples thereof include woven fabrics, knitted fabrics, non-woven fabrics, sheets or films of various thermoplastic resins and thermoplastic elastomers, and those having uneven patterns such as grain can be used. Further, a foam of thermoplastic resin such as polyolefin, polyvinyl chloride or polystyrene, a foam of thermosetting resin such as polyurethane, or foam of rubber such as cis-1,4-polybutadiene or ethylene-propylene copolymer. The body can also be used. Further, these may be used alone or in the form of a laminated body in which two or more kinds are laminated.

[0007] As a particularly preferable skin material, there is a laminate in which a vinyl chloride sheet or a polypropylene-based thermoplastic elastomer sheet is used as a surface layer material, and a polypropylene foam sheet is lined on the surface layer material. In such a laminated body, the thickness of the sheet as the surface layer material is 0.3 to 0.8 mm.
The thickness of the foamed sheet as the backing material is about 2 to 5 mm, and the expansion ratio is preferably about 3 to 30 times, although it depends on the material resin. When such a skin material is used, it may be preheated or preshaped in order to adjust the tensile stress, elongation, etc. of the skin material.

An example of the method for producing a multilayer molded article according to the present invention will be described below. The apparatus used in the manufacturing method of the present invention comprises a male mold (2) and a female mold (1), for example, as shown in FIG. A clamper (3) for fixing a skin material movable in the mold clamping direction by a spring or the like is arranged. This clamper (3) is used depending on the complexity of the product shape. A pin for controlling the elongation of the skin material (6) may be arranged on this clamper, and the skin material (6) is sandwiched between the clamper (3) and the female mold (1). The elongation of the skin material may be controlled by adjusting the holding force. Further, the male mold is provided with a molten resin supply port (4). If necessary, one or both of the molds may be provided with a cooling pipe.

Next, a manufacturing example using such an apparatus will be described. First, the skin material (6) is positioned between the male and female molds in the opened state (Fig. 1), then the female mold (1) is lowered to an appropriate position, and the molten resin supply port provided in the mold. From (4), the molten thermoplastic resin (5) at 175 to 195 ° C. is supplied between the skin material (6) and the male mold (2) (FIG. 2). At this time, if the supply temperature of the molten thermoplastic resin deviates from this range, the obtained molded product is likely to be deformed or the texture is apt to be impaired. The cavity clearance formed by the male mold and the female mold at the time of supplying the molten resin is preferably in the range of 5 to 100 mm.

Next, almost simultaneously with or after the completion of the supply of the molten resin, the female mold (1) is lowered and the mold is closed to pressurize the molten thermoplastic resin (5) and spread it into the mold to shape it. (Fig. 3). The pressing surface pressure gradually increases as the molten resin is pushed into the mold by the downward movement of the female mold, and the shaping is completed when the set pressing surface pressure is reached. The pressing surface pressure at the completion of this shaping is 30 to 95 kg / cm.
Set within the range of 2. Further, the speed of lowering the female mold (1) is 1 to 3 from the completion of the molten resin supply to the completion of the shaping.
It is preferable to adjust the time to be about a second.

Immediately after the shaping, pressure cooling is performed. It is extremely important to control the pressing surface pressure and the pressing time during this pressure cooling. First, the pressing surface pressure is set to be equal to or lower than the set pressure when the molten resin shaping is completed, and this pressing surface pressure may be constant during the pressing time or may be changed during the pressing. When the pressure is changed, the pressing surface pressure may be 0 at any stage.

On the other hand, the pressing time depends on the pressing surface pressure during pressing and cooling, and the product of the pressing surface pressure and the pressing time is 100 to 1500 kg.
/ Cm2 ・ Set so that it is in the range of seconds. At this time, if the product of the pressing surface pressure and the pressing time is lower than 100 kg / cm2, the obtained multilayer molded article will be greatly deformed, and 1500 kg
If it exceeds / cm2, the texture of the skin material of the multi-layer molded product is significantly impaired. When the pressure surface pressure is constant during pressure cooling, the product of the pressure surface pressure and the pressure time is changed, and when the pressure surface pressure is changed during pressure cooling, the pressure cooling condition is It is necessary to make the total of the product of the pressing surface pressure and the pressing time within the above range. In addition, cooling may be performed by forcedly cooling by passing a cooling medium such as water through a cooling pipe provided in advance in one or both molds, or by blowing air from outside the mold, or by natural cooling at room temperature. The optimum method may be selected according to various conditions such as resin temperature, product thickness, and mold set temperature.

After cooling under pressure, the female mold is raised to open the mold, and a multilayer molded product (8) consisting of a thermoplastic resin core material and a skin material is taken out. Needless to say, the above-described device and the manufacturing method using the device are one embodiment of the present invention, and the present invention is not limited to this device and method.

[0014]

EFFECTS OF THE INVENTION According to the present invention, the skin material is preliminarily supplied between the upper and lower molds, the molten resin is then supplied, the mold is closed and pressurized, and the skin material is laminated on the surface of the thermoplastic resin core material to form a multilayer molding In the method of obtaining a product, it is possible to obtain a multi-layer molded product that maintains a good surface appearance.

[0015]

The present invention will be described in more detail with reference to the following examples, but it goes without saying that the present invention is not limited thereto.

Example 1 A multi-layer molded article composed of a skin material and a thermoplastic resin core material was manufactured by the method shown in FIGS. Polypropylene as a thermoplastic resin for the core material (Sumitomo Noblen BPZ50
77, MI (230 ° C.) = 45, manufactured by Sumitomo Chemical Co., Ltd., a polypropylene-based thermoplastic elastomer sheet having a thickness of 0.6 mm and a polypropylene foam sheet (Toray Pef PPAM 20030, foaming ratio 20 times, thickness 3 m) as a skin material.
m, manufactured by Toray Industries, Inc.) was laminated by heat. First, the skin material (6) is placed between the male and female molds in the open state, then the female mold (1) is lowered, and the molten resin supply port (4) provided in the male mold (2) is used. Molten polypropylene (5) was fed between the skin material (6) and the male mold (2).
Next, almost simultaneously with the completion of the supply of the molten polypropylene, the female mold (1) is lowered, the mold is closed, the molten polypropylene (5) is pressurized, and the molten polypropylene (5) is spread in the mold to shape. After completion of shaping, pressure cooling is performed. After cooling under pressure, the female mold is opened to obtain a multilayer molded product (8) including a polypropylene core material and a skin material. The molding conditions at this time are as follows. -Melted polypropylene temperature: 190 ° C-Mold temperature: Female mold 30 ° C, male mold 40 ° C-Pressure surface pressure after completion of shaping: 85 kg / cm2-Pressure condition after completion of shaping: 85 kg / cm2 x 2 seconds 0 kg / cm2 x 38 seconds (total product of pressure and pressure: 170 kg / cm
2-second) The obtained multilayer molded product had a good appearance with no breakage of the skin material, no deformation.

Comparative Example 1 A multilayer molded article was produced in the same manner as in Example 1 except that the temperature of molten polypropylene was changed to 205 ° C. In the obtained multi-layer molded product, the polypropylene foam layer of the skin material was destroyed and pitting occurred on the surface.

Comparative Example 2 A molded product was produced in the same manner as in Example 1 except that the surface pressure applied during shaping and the pressure conditions after completion of shaping were as follows.・ Pressurized surface pressure after completion of shaping: 60 kg / cm 2 ・ Pressure condition after completion of shaping: 60 kg / cm 2 × 1.
5 seconds 0 kg / cm2 x 38 seconds (Sum of product of surface pressure and time: 90 kg / cm2
-Second) In the obtained multi-layer molded product, the polypropylene foam layer of the skin material was not broken, but a large deformation occurred.

Example 2 By the method shown in FIGS. 1 to 3, a multilayer molded article composed of a skin material and a thermoplastic resin core material was manufactured. Polypropylene as a thermoplastic resin for the core material (Sumitomo Noblen BPZ507
7, MI (230 ° C.) = 45, and a laminate in which a 0.5 mm thick polyvinyl chloride sheet as a skin material and a polypropylene foam sheet (Toray PEPF PPAM20030, foaming ratio 20 times, thickness 3 mm, manufactured by Toray Industries, Inc.) are laminated by heat. Sheets were used. A molding process was performed in the same manner as in Example 1 except that the molding conditions were as follows. -Melted polypropylene temperature: 185 ° C-Mold temperature: Female mold 25 ° C, male mold 60 ° C-Pressure surface pressure after completion of shaping: 75 kg / cm2-Pressure condition after completion of shaping: 75 kg / cm2 x 3 seconds 10 kg / cm2 x 35 seconds (total product of surface pressure and pressing time: 575 kg / cm
2-second) The obtained multilayer molded product had a good appearance with no breakage of the skin material and no deformation.

Example 3 A multi-layer molded article composed of a skin material and a thermoplastic resin core material was manufactured by the method shown in FIGS. Polypropylene as the thermoplastic resin for the core material (Sumitomo Noblen BTE71,
MI (230 ° C.) = 70,) and a thickness of 0.
5mm PVC sheet and polypropylene foam sheet (Toray PEP PPAM2003, foaming ratio 20 times, thickness 3m
m, manufactured by Toray Industries, Inc.) was laminated by heat. Example 1 except that the molding conditions were as follows
A molding process was performed in the same manner as in. -Melted polypropylene temperature: 179 ° C-Mold temperature: Female mold 30 ° C, male mold 40 ° C-Pressure surface pressure after completion of shaping: 80 kg / cm2-Pressure condition after completion of shaping: 80 kg / cm2 x 10
Sec 10 kg / cm2 x 30 sec (total of product of surface pressure and pressure: 1100 kg / c
The obtained multi-layer molded article had a good appearance with no breakage of the skin material and no deformation.

Comparative Example 3 A multilayer molded article was produced in the same manner as in Example 2 except that the molding conditions were as follows. -Melted polypropylene temperature: 190 ° C-Mold temperature: Female mold 25 ° C, male mold 60 ° C-Pressure surface pressure after completion of shaping: 75 kg / cm2-Pressure condition after completion of shaping: 75 kg / cm2 x 20
20 kg / cm2 x 20 seconds (total of product of surface pressure and pressing time: 1900 kg / c
In the obtained multilayer molded article, the polypropylene foam layer of the skin material was destroyed and pitting occurred on the surface.

[Brief description of drawings]

FIG. 1 is a schematic view of a manufacturing method of the present invention, showing a state in which a skin material is placed between unclosed male and female molds.

FIG. 2 is a schematic view of the manufacturing method of the present invention, showing a state in which a molten thermoplastic resin is supplied between the skin material and the cavity surface of the male mold.

FIG. 3 is a schematic view of the manufacturing method of the present invention, showing a pressurized cooling state at the time of completion of shaping after supplying the molten thermoplastic resin and thereafter.

[Explanation of symbols]

 1: Female mold 5: Molten resin 2: Male mold 6: Skin material 3: Clamper 7: Resin passage 4: Resin supply port 8: Core resin layer

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display area B29L 31:58 4F

Claims (3)

[Claims] 1. A skin material is supplied into a pair of unclosed male and female molds, and then a molten thermoplastic resin is supplied into the molds through a resin passage provided in the molds to clamp both molds. Then, the molten resin is shaped in a mold, and then, in a method for producing a multilayer molded article obtained by laminating a skin material on the surface of a thermoplastic resin core material, which comprises cooling under pressure, The temperature supplied to the molding die is 175 to 195 ° C., the surface pressure applied when the shaping is completed is 30 to 95 kg / cm 2, and the product of the surface pressure applied and the pressure application time is 100 to 1500 kg / cm2
A method for producing a multilayer molded article, which comprises cooling under pressure so as to be in the range of seconds. 2. The method for producing a multilayer molded article according to claim 1, wherein the thermoplastic resin is a polypropylene resin. 3. The melt flow index (MI) of polypropylene resin at 230 ° C. is 15 to 200 g / 10.
The method for producing a multilayer molded article according to claim 2, which is in the range of minutes.