JP3232722B2 - Manufacturing method of hollow molded body - Google Patents

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 hollow molded article of a thermoplastic resin bonded to a skin material.

[0002]

2. Description of the Related Art As a method for producing a hollow molded article using a thermoplastic resin, a blow molding method and a gas injection molding method are well known. However, in the skin material pasting synthetic type by the blow molding method, since the thickness of the skin material bonding thermoplastic resin hollow molded body cannot be controlled, it is difficult to obtain a uniform and desired thickness of the molded body. In addition, there are many problems that the thermoplastic resin used is limited by the flow characteristics and viscosity in the molten state, and that the shape of the molded product cannot correspond to the shape having a high blow ratio. there were.

On the other hand, a method for molding a thermoplastic resin hollow molded article which is not so much governed by the flow characteristics and viscosity of a molten thermoplastic resin, can control the thickness thereof, and can cope with a shape having a high blow ratio. Although a gas injection molding method is known as such, it has been difficult to perform a skin material pasting and forming method by this method.

[0004]

SUMMARY OF THE INVENTION
The present inventors are not limited by the resin used, have a uniform wall thickness, are easy to control the wall thickness, and are capable of coping with a shape having a high blow ratio. As a result of diligent studies on the production method of the present invention, the present invention was reached.

[0005]

That is, the present invention is capable of sliding in a mold clamping direction on one or both of a fixed mold and a movable mold having a cavity surface formed in a desired three-dimensional shape. 50 to 1000 kg / cm ² at 23 ° C. and 8
A skin material having a tensile modulus of 5 to 100 kg / cm ² at 0 ° C. is fixed on each parting surface of both molds in an open state, and then 50% by volume with respect to the cavity volume between the skin materials. After supplying a less amount of the molten thermoplastic resin, both molds are closed to wrap the molten thermoplastic resin between the skin materials, and then penetrate one of the skin materials into the molten thermoplastic resin. Disclosed is a method for producing a thermoplastic resin hollow molded article laminated with a skin material, wherein a fluid discharge pin is protruded, a fluid is supplied from a distal end of the discharge pin to form a hollow part, and the solid part is cooled and solidified. .

Hereinafter, the present invention will be described in detail. The mold used in the present invention includes a fixed mold (1a) and a movable mold (1b) that can move up and down, as illustrated in FIG. 1, and each mold is attached to a press device. I have. These molds have cavity surfaces (2a, 2b) corresponding to the product shape, and at least one cavity surface of these molds has a fluid discharge pin (4) slidable in the mold clamping direction. At least one pin is provided so that the pin tip faces the other cavity surface. The fluid discharge pin (4) is embedded in a mold, protrudes during molding of a hollow molded body, slides in the mold so as to retreat to a cavity surface after molding, and has an end portion connected to a fluid supply pipe ( 10).

As the sliding device (8) for the fluid discharge pin (4), a commonly known driving device such as air or hydraulic pressure is adopted, but a simple structure is preferable. A fluid discharge hole (3) is provided at the tip of the fluid discharge pin (4), and the fluid discharge hole (3) may be the tip of the pin, but the fluid normally blows out in all directions. In the vicinity of the tip of the pin, a plurality of pins, typically 4
Are provided. Needless to say, the location and number of the fluid discharge holes (3) are appropriately selected according to the size and shape of the molded body.

The fixed type (1a) in such an open state
The ends of the skin material are fixed to the respective parting surfaces (5a, 5b) such that the skin materials (6a, 6b) cover the cavity surfaces of both molds of the movable mold (1b). (Second
Figure) Any method of fixing the skin material on the parting surface (5a, 5b) is possible, but it is simple to use a double-sided adhesive tape.
May be used. The skin material used here is a surface decoration of a target hollow molded body, a cushion body,
It is appropriately selected depending on the intended use of such heat insulating material, in order to serve molten thermoplastic resin (7) with a suitable thickness distribution wrap between the skin material, 50 to 100 at 23 ° C.
0 kg / cm ² , preferably 80 to 300 kg / cm ²
In addition, it is softened by heating with a molten thermoplastic resin wrapped between the skin materials, so that the tensile elasticity at 80 ° C. is 5 to 100 kg / cm ² , preferably 10 to 10 kg / cm ² .
It is necessary to be 30 kg / cm ² , whereby a molded product having a high blow ratio and a volume ratio of the hollow portion of 50% or more can be obtained. As such a skin material,
For example, papers, woven fabrics, non-woven fabrics, sheets or films of a thermoplastic resin or a thermoplastic elastomer alone or in combination of these are used. May be applied. Moreover, the skin material may be the same or different at the top and bottom depending on the purpose of use of the molded article. Although the thickness of the skin material varies depending on the material, it is sufficient that the thickness is such that at least the molten thermoplastic resin is wrapped between the skin materials and can be shaped, and is usually about 0.5 to 4 mm.

Next, a molten thermoplastic resin is supplied from outside the mold by, for example, an extruder (not shown) between the upper and lower skin materials covering the cavity surface. (Third
In this resin supply, it is preferable to move the molten resin supply port from outside the mold in the horizontal direction or to move the lower mold horizontally to supply the molten resin uniformly on the skin material. The amount of the supplied molten thermoplastic resin is usually less than 50% by volume of the mold cavity volume formed by both molds. When the amount of the supplied resin exceeds 50% by volume, the volume of the hollow portion of the obtained molded article becomes small, and sufficient performance as a hollow molded article cannot be expected. The lower limit of the supplied resin amount is generally 5% by volume, but is not particularly limited as long as the hollow molded body can be formed, and is appropriately selected so as to have a desired resin thickness.

The thermoplastic resin used here is preferably wrapped with a suitable thickness distribution between the skin materials in the molten state, and therefore preferably has excellent fluidity in the molten state.
Such thermoplastic resins include polyethylene, polypropylene, polystyrene, acrylonitrile styrene,
General thermoplastic resins such as butadiene copolymer, polyvinyl chloride, polyamide, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene ether, styrene / acrylonitrile copolymer, etc. Or a polymer alloy using these thermoplastic resins. In addition, these thermoplastic resins may be talc, wollastonite,
It may contain an inorganic filler such as glass fiber, and, of course, may contain various additives and coloring agents such as various antioxidants and ultraviolet inhibitors commonly used.

Immediately after supplying the molten thermoplastic resin (7), the movable mold (1b) is lowered and the two molds (1a, 1b) are lowered.
Close. At this time, the molten thermoplastic resin supplied between the skin materials (6a, 6b) is wrapped between the skin materials while stretching the skin material. (FIG. 4) In this state,
The fluid discharge pin (4) is projected through one of the skin materials so that the tip end is in the molten thermoplastic resin (fifth).
(Fig.), Fluid is supplied from the fluid discharge hole (3). here,
The fluid discharge pin (4) needs to protrude without penetrating the other skin material, and it is preferable that the fluid discharge hole (3) is located substantially at the center between the two skin materials. As the fluid, various gases such as air, nitrogen, helium, carbon dioxide, and oxygen, and liquids such as water are used.These are used to spread the molten thermoplastic resin together with the skin material in a closed cavity space. Usually required 2-10kg / c
It is used in a pressurized state of about m ² . Among these fluids, gas is preferably used in terms of workability and the like, and among them, inert gas such as air, nitrogen, carbon dioxide gas, especially compressed air is preferably used from the viewpoint of economy and safety.

By supplying a fluid into the molten thermoplastic resin, the molten resin swells like a balloon by the fluid, and forms a hollow portion (9) and spreads the skin material to adhere to the cavity surface. At the same time, a hollow molded body in which the thermoplastic resin and the skin material are thermocompression bonded is formed.
(FIG. 6) Cooling of the mold is started while maintaining this state,
When the fluidity of the resin disappears, the supply of the fluid is stopped, the mold is cooled, and the molten resin is completely solidified. Then, the movable mold (1b) is raised to open the mold, and the skin material is bonded. The molded thermoplastic resin hollow body is taken out. After the molten resin is cooled and solidified, the fluid discharge pin (4) protruding into the molten resin is lowered and stored in the original position. However, when the resin is completely solidified, the pin slides. Since the fluidity may be deteriorated, it is preferable to lower the molten resin when it has solidified to such an extent that the fluidity is lost.

[0013] Thus, a hollow molded article of the thermoplastic resin-laminated thermoplastic resin is produced, and a pin mark (11) may remain on the molded article after the fluid discharge pin (4) is pulled out. By making the thickness as small as possible, it can be kept to a fine trace level, and depending on the thermoplastic resin or skin material used, it is possible to make the appearance almost invisible due to its restoring force.

[0014]

According to the production method of the present invention, the thickness can be uniform and the thickness can be easily controlled without being restricted by the resin used, and the blow ratio can be increased. It is possible to easily form a skin molded thermoplastic resin hollow molded article having a volume ratio of the hollow portion of 50% by volume or more, and the hollow molded article thus obtained is lightweight. And it is widely used in various applications as a skin bonded product.

[0015]

EXAMPLES 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. In the following Examples and Comparative Examples, the tensile modulus of the skin material was measured by the following method. Tensile modulus: A tensile test was performed with a tensile tester according to JIS-K7113. The test piece used was a dumbbell No. 1 test piece, and the sampling method was the sheet winding direction (M
D) and a direction perpendicular thereto (TD). The test was performed under two conditions of normal temperature (23 ° C.) and 80 ° C., and the tensile speed was 50 mm / min. For the tensile modulus, the slope of a straight line up to 5% elongation was taken from the load-elongation diagram.

Example 1 In accordance with the steps shown in FIGS. 1 to 6, a thermoplastic resin hollow molded article laminated with a skin material was produced by the following method. The mold shown in FIG. 1 is opened (the fluid discharge pin is housed inside the mold except for the tip of the pin), and the mold parting surfaces (5a, 5b) of the upper and lower molds (1a, 1b) are removed. In each case, a 3.2 mm thick skin material in which a soft vinyl chloride sheet was laminated on a polypropylene foam sheet as a surface layer was fixed using a double-sided tape. (FIG. 2) A molten polypropylene resin having a resin temperature of 230 ° C. equivalent to 40% by volume with respect to the cavity space is put on a skin material spread over the cavity surface of the fixed mold (1a) by a portable extruder. Supplied.
(FIG. 3) Immediately after the resin is supplied, the movable mold (1b) is lowered to clamp both molds (FIG. 4), and then the fluid discharge pin (4) is fixed to the cavity surface (2a) of the fixed mold (1a). The fluid ejection hole (3) was made to penetrate the skin material and protrude into the molten resin, so that the fluid discharge hole (3) was located substantially at the center between the skin materials. (FIG. 5) After 15 seconds from the mold clamping, via the fluid supply pipe (10),
7.5 kg / cm ² of compressed air was supplied into the molten resin from the fluid discharge hole (3). (FIG. 6) After the mold was cooled for 120 seconds from the start of the supply of compressed air, the mold was opened, and a skin material-laminated thermoplastic resin hollow molded article as shown in FIG. 7 was obtained. Approximately 100 seconds after the start of cooling, the supply of compressed air was stopped, and the fluid discharge pin (4) was stored in the original position. The obtained molded article was excellent in deep drawability and also had a good appearance. The deep drawability is obtained by comparing the dimension A of the mold cavity corner with the dimension B of the corner of the product hollow molded product. × less than B
Was evaluated. This evaluation method is the same in the following.

EXAMPLE 2 A thermoplastic resin bonded to a skin material in the same manner as in Example 1 except that a 3.2 mm-thick laminated sheet obtained by laminating a hard vinyl chloride sheet as a surface layer on a polypropylene foam sheet is used. A hollow molded body was obtained. The obtained molded article was excellent in deep drawability and also had a good appearance.

Example 3 As a skin material, a polyester non-woven fabric (having a basis weight of 245 g /
m ² , manufactured by Hayashi Telemp Co., Ltd.), and a skin molded laminated thermoplastic resin hollow molded article was obtained in the same manner as in Example 1. The obtained molded article was excellent in deep drawability and also had a good appearance.

Comparative Examples 1 and 2 A polyester-based nonwoven fabric (200 g / weight)
m ^2, manufactured by Dynic Corp.), was produced except for using polyester fabrics (Kawashima Co.) respectively in the same manner as in Example 1 skin material Hagonetsu thermoplastic resin hollow molded body. As shown in Table 1, Comparative Example 1 using a polyester-based nonwoven fabric having a low tensile modulus at room temperature as a skin material
In the case of, the hollow portion was not sufficiently formed, and a product having a desired shape could not be obtained. Further, in the case of Comparative Example 2 in which a polyester-based fabric having a high tensile modulus at 80 ° C. was used as the skin material, the deep drawability was poor, and unevenness occurred on the surface of the molded body.

[0020]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic view of a production process of a skin-bonded thermoplastic resin hollow molded article of the present invention, showing a mold before the start of production.

FIG. 2 is a schematic view of a manufacturing process of a hollow thermoplastic resin bonded body of a skin material of the present invention, showing a state where the skin material is fixed to a mold parting surface.

FIG. 3 is a schematic view of a manufacturing process of a skin material-laminated thermoplastic resin hollow molded article of the present invention, showing a state when a molten thermoplastic resin is supplied onto a skin material.

FIG. 4 is a schematic view of a manufacturing process of a hollow molded article of a thermoplastic material laminated with a skin material of the present invention, showing a state where a mold is closed and a molten thermoplastic resin is wrapped between the skin materials.

FIG. 5 is a schematic diagram of a manufacturing process of a skin material-laminated thermoplastic resin hollow molded article of the present invention, in which a fluid discharge pin is projected into a molten thermoplastic resin wrapped between skin materials. Indicates the status.

FIG. 6 is a schematic view of a manufacturing process of a skin-molded thermoplastic resin hollow molded article of the present invention, in which a fluid is supplied from a fluid discharge pin in a molten thermoplastic resin to form a hollow portion. Indicates the status.

FIG. 7 is a schematic view of a skin-bonded thermoplastic resin hollow molded article of the present invention.

[Explanation of symbols]

1a: Fixed mold 1b: Movable mold 2a: Fixed mold cavity surface 2b: Movable mold cavity surface 3: Fluid ejection hole 4: Fluid ejection pin 5a: Fixed mold parting surface 5b: Movable mold parting surface 6a: Skin material 6b: Skin material 7: Thermoplastic resin 8: Fluid discharge pin sliding device 9: Hollow portion 10: Fluid supply path 11: Pin mark A: Mold cavity corner -Part size B: Hollow molded body corner part size

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeyoshi Matsubara 2-10-1 Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Co., Ltd. (56) References JP-A-2-1022021 (JP, A) JP-A Sho 60-54836 (JP, A) JP-A-61-123514 (JP, A) JP-A-6-136189 (JP, A) JP-A-60-54497 (JP, U) European Patent Application Publication 322285 (EP, A) 1) (58) Investigated field (Int. Cl. ⁷ , DB name) B29C 45/00-45/24 B29C 39/10 B29C 49/00-49/80

Claims (2)

(57) [Claims] 1. A mold having a fluid ejection pin slidable in a mold clamping direction on one or both of a fixed mold and a movable mold having a cavity surface formed in a desired three-dimensional shape. 50-1000 kg / at 23 ° C
cm ^2, and a skin material having a tensile modulus of 5 to 100 kg / cm ² at 80 ° C., molds each path in an open state -
Then, the molten thermoplastic resin is supplied between the skin materials in an amount of less than 50% by volume based on the cavity volume between the skin materials, and then the molds are closed to place the molten thermoplastic resin between the skin materials. Wrapping, then protruding the fluid discharge pin into the molten thermoplastic resin by penetrating one skin material, supplying fluid from the discharge pin tip to form a hollow portion, cooling and solidifying. Method for producing a thermoplastic resin hollow molded article bonded to a skin material. 2. A thermoplastic resin hollow molded article laminated with a skin material produced by the method according to claim 1.