JPS5810217B2 - PLASTIC FUKU GOUTAINO SOUCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for simultaneously and batch or continuous production of internally foamed composite structures completely coated with a solid skin layer using various thermoplastic resins.

Conventionally, a solid shell molded product is made in advance by rotary molding or blow molding, and a molten foam is injected into the molded product, or an unfoamed resin material containing a foaming agent is filled inside the solid skin and then heated and foamed. A plastic composite in which an internal foam material was covered with a solid outer skin layer was produced.

Such plastic composites often need to be manufactured into a large number of products in a short period of time, such as fishing floats or cushioning materials.

However, in the above-mentioned conventional method, it is necessary to mold the solid outer skin and the internal foam material in separate steps, which results in a long molding cycle and is inefficient and uneconomical.

In addition, the internal foam material and the solid outer skin are not sufficiently integrated, and the adhesion between the inner and outer layers is not sufficient. Due to shrinkage during the process and sometimes excess gas generation, gas stagnation occurs between the outer skin and the inner layer, creating a space and not integrating the inner and outer layers, resulting in a decrease in strength. It's hard to call it a body.

Furthermore, conventionally, a foamed plastic inner layer of thermoplastic resin is made in advance by various molding methods, and the core material of the inner layer foam material is sandwiched between a blow molding machine or a preformed thermoplastic resin plate and fused under pressure. There are methods such as the following, but in both cases it is necessary to make the foam board and the outer skin board in separate processes, the molding cycle takes a long time, the process is complicated, and it is not economical.

Moreover, in this pressure welding method of resin plates, it is necessary to weld the peripheral edge of the thermoplastic resin plate that has been molded and cooled and solidified, and then cover the inside with a foamed resin plate, and the welding of the resin plates to each other is difficult. There was a drawback that it was not carried out sufficiently and peeling easily occurred.

Further, in this welding method, air remains between the core material of the foamed resin plate and the resin plate of the solid outer shell, which deteriorates the quality of the molded product and has the disadvantage that the strength is not sufficient.

In view of these conventional drawbacks, the present invention has been made based on various studies and provides a method and apparatus for molding a plastic composite that are free from these drawbacks.

The present invention extrudes molten thermoplastic resin into a hollow shape using an extruder equipped with a circular die to form a solid outer skin layer, and suppresses the molding split mold from opening in a direction perpendicular to the longitudinal center axis of the cylindrical shape. Fittingly closes one end far from the circular die, and providing a small opening in the outer skin layer at the end near the circular die and in the center end of the split mold;
The hollow outer skin layer and an injection die of an injection device provided on the central axis in the longitudinal direction inside the circular die and having a smaller diameter than the circular die and capable of sliding on the central axis are inserted into the small opening. After inserting and injecting a foamable molten thermoplastic resin containing a foaming agent into the outer skin layer, the injection die is pulled out,
After pressing with the opening closing mold provided in the molding split mold to seal the resin in the small opening and the mold, molding along the inner surface of the mold 1
This is a method of molding a plastic composite in which the inner foam is covered with a solid outer skin layer.

Further, an apparatus used in the above molding method,
An injection device and an injection die movable on the central axis of the die are provided inside the circular die of the extrusion molding machine for a hollow cylindrical body, and further on the central axis farther from the extrusion position of the circular die, The mold can be opened and closed in a direction perpendicular to the central axis, and a split mold for molding is provided, which has a small opening at the center end near the circular die on the central axis and closes the other end. The apparatus for molding a plastic composite is provided with an opening closing mold in which the small opening is used as an opening closing mold when the injection die is inserted into and withdrawn from the small opening. .

Unlike conventional plastic composites, the present invention provides a method for molding a plastic composite in which the internal foam layer is completely covered with a solid outer skin layer in one step, and both layers are tightly integrated into one body. This is the completed device.

The plastic composite of the present invention has no seams in its solid outer shell, does not require any post-filling processing unlike those made using the blow method, and has excellent structural strength because it is a complete one-step integrated product. It is economically advantageous because it requires only a few steps, and since it is an integrated process and can be operated continuously, uniform standard products can be mass-produced in a short period of time.

Because it is completely coated with MataSolid row skin, this product can be used stably for long periods of time without flooding when used as fishing floats or floats for seaweed cultivation nets in the open ocean with strong waves. It is also extremely durable and an excellent material for marine disaster buoys.

In addition, since the products of the present invention are lightweight and flexible, they can be easily manufactured into various shapes for household use in a single process.

Thermoplastic resins for the solid skin of the present invention include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polycarbonate, acrylonitrile, polyamide, acrylic-styrene copolymer, acrylonitrile-
All thermoplastic resins such as butadiene-styrene copolymers and their waste resins can also be used.

Further, as the foamable thermoplastic resin for the inner layer core material of the present invention, gas-impregnated resins such as polystyrene, polypropylene, polyvinyl chloride, acrylonitrile-butadiene-styrene (aliphatic hydrocarbons having 3 to 7 carbon atoms, such as propane , butane, pentane, hexane, etc.) or a thermally decomposable blowing agent.

The thermally decomposable blowing agent used in the present invention is preferably a decomposable blowing agent such as azodicarbonamide, dinitrone pentamethylenetetramine, paratoluenesulfonyl semicarbazide, pp'oxybisbenzenesulfonylhydrazide, azobisisobutyronitrile, etc. .

The invention will now be explained with reference to the figures.

FIG. 1 is a longitudinal cross-sectional view of an apparatus showing one embodiment of the present invention, and FIGS. 2 to 4 are partial vertical cross-sectional views mainly showing a circular die injection die and a molding split mold. The steps of the method are shown.

In FIG. 1, a raw material for a thermoplastic resin 1 for solid opening such as polyethylene is heated from a hopper 2 by a heating wire 3 to become a molten resin 4, which is then transferred to a circular cylinder attached in a crosshead shape by an extrusion screw 6 rotated by a rotating device 5. - It is extruded from the diamond as a parison of the hollow cylindrical body 8 in a softened state.

On the other hand, as an example of the resin that will become the inner layer foam, the mixed raw material 9 of polystyrene and azodicarbonamide is placed in the hopper 1.
An unfoamed molten thermoplastic resin 14 is heated from 0 by a heating wire 11 and sent by a screw 13 which is rotated by a rotating device 12.
becomes.

The resin 14 is sent by an injection plunger 11 which is press-fitted into a cylinder 16 by an injection device 15 and is injected toward an injection die 18.

This cylinder 16 has a gas discharge hole 19 formed therein.

This cylinder 16 and injection die 18 are an injection device,
It is located on the central axis of the circular die, and can be slid up and down in FIG. 1 on the central axis by a ball bearing 20, and the injection die 18 can also be moved up and down by sliding up and down.

At the bottom of this cylinder 16 and above the injection die 18, the molten resin 14 can be circulated and discharged by the pressure of the injection plunger 17 during injection, but when the pressure is released after injection, the molten resin 14 is prevented from leaking. Dru ring prevention valve 21
is being made.

At a little distance from this circular die γ, there is a left W22 and a right die 23, which are the two-part cross-section of the molding split mold. They are pressed onto the shaft from the left and right and are fitted together as shown in FIG. 4, which will be described later.

The molding split molds 22 and 23 are provided with mold surfaces 24 and 25, and the outside of the parison of the hollow cylindrical body 8 is brought into contact with these surfaces as will be described later.

In addition, the split molds 22 and 23 for molding are formed when the circular diamond is moved forward and backward in a direction perpendicular to the upper and lower center axis of FIG. 1 and is pressed for molding in the molds 22 and 23. Opening closing molds 26 and 27 for pressing and sealing the small opening parison are provided in the shape of pistons for opening and closing.

In an apparatus with such an arrangement, as shown in FIG.
2. When the parts 23 are brought close to each other, the end part 28 of the hollow cylindrical body 8 which is far from the circular diamond is pressed from the periphery by the mold, and the end part 28 which is still in a softened state is joined. and is occluded.

At this time, the injection die 18 enters the opening 30 in the end 29 of the hollow cylindrical body 8, which is still open, near the circular die 7, and the foamable molten thermoplastic resin 14 is ejected from the injection die 18. eject.

As a result of this injection, the mold is filled with the foamed resin 14, as shown in FIG.

Thus, as shown in FIG. 4, the mold 22.23 was filled and the solid outer skin of the hollow cylindrical body 8 was pressed against the mold inner surface 24.25, and the foamed molten resin 14 adhered to the solid outer skin inner surface and became integrated. A complex is obtained.

In FIG. 4, the adhesive part 31 protrudes in an onion shape, but it can also be made into a spindle shape depending on the mold, so that composites of various shapes can be manufactured.

The molds 22 and 23 are opened left and right to take out the composite after cooling with cooling water or the like passing through the mold cooling equalization fluid passage hole 32.

This composite body is well-integrated, structurally strong, lightweight, and floats underwater and in seawater, making it an excellent and durable float for fishing.

It was also extremely excellent as a cushioning material.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view showing a method and apparatus for molding a plastic composite, which represents one embodiment of the present invention. 2 to 4 are partial longitudinal sectional views of the vicinity of the injection die in FIG. 1. 1... Thermoplastic resin 1.2... Hopper, 3... Heating wire, 4... Molten resin,
5...Rotating device, 6...Extrusion screw, 7...Circular die, 8...
Hollow cylindrical body (parison), 9...Blowing agent and thermoplastic resin mixed raw material, 10...Hopper, 11.
... Heating wire, 12 ... Rotating device, 13.
... Extrusion screw, 14 ... Unfoamed molten thermoplastic resin, 15 ... Injection device, 16 ...
... Cylinder, 17 ... Injection plunger, 18 ... Injection die, 19 ... Gas discharge hole, 20 ... Ball bearing, 21 ...・
...Druling prevention valve, 22...Left type,
23...Right mold, 24.25...Mold inner surface, 26.21...Opening closing mold, 28.29.
...End, 30...Opening, 31...
...Sealing adhesive part, 32...Mold cooling fluid passage hole.

Claims (1)

[Scope of Claims] 1. Molten thermoplastic resin is extruded into a hollow cylindrical shape by an extruder equipped with a circular die to form a solid outer skin layer, and molding is performed from the outer periphery in a direction perpendicular to the longitudinal center axis of the cylindrical body. A split mold is press-fitted to close one end far from the circular die, and a small opening is provided in the outer skin layer at the end near the circular die and at the center end of the split mold. a hollow outer skin layer, provided on the central axis in the longitudinal direction inside the circular die and having a smaller diameter than the circular die;
Inserting an injection die of an injection device capable of sliding on the central axis into the small opening, injecting a foamable molten thermoplastic resin containing a foaming agent into the outer skin layer, and then pulling out the injection die; After pressing with an opening closing mold provided in the molding mold to seal the resin in the small opening and the mold, the inner layer foam and the solid outer skin layer are molded into one body, so that the inner layer foam becomes a solid outer layer. A method for molding a plastic composite characterized by being covered with a cortical layer. 2. In Claim 1, an injection device and an injection die movable on the central axis of the die are provided inside the circular die of the extrusion molding machine for a hollow cylindrical body, and furthermore, an injection device and an injection die are provided that are movable on the central axis of the die, and further, from the extrusion position of the circular die. A molding splitter having a shape that allows the mold to be opened and closed in a direction perpendicular to the central axis on a separate central axis, and has a small opening at the central end near the circular die on the central axis and closes the other end. A plastic composite, characterized in that an opening closing mold is attached to a split mold for molding, in which a mold is disposed and the small opening can be opened and closed as the injection die is inserted into and withdrawn from the small opening. Body shaping device.