JPH079468A - Method for producing thermoplastic resin molded body - Google Patents

Abstract

(57) [Summary] [Structure] In press molding of a thermoplastic resin using upper and lower molds, a protrusion is made on the cavity surface of the upper mold 1 or the lower mold 2.
A mold having a retractable tubular protrusion 3 and a resin supply port 4 provided in the tubular protrusion 3 is used. With the mold opened, the protrusion 3 is protruded to partially The intermediate layer 8 having the holes 10 is placed on the mold 2 with the protrusions 3 penetrating the holes 10 and a fixed amount of molten resin is supplied from the resin supply port 4, and the mold is closed and added. It is a method for producing a thermoplastic resin molded body, which is characterized by pressing and shaping. According to the method of the present invention, by moving the tubular protrusion 3 up and down, the required amount of molten resin can be supplied to the upper side, the lower side of the intermediate layer 8 or the interlayer of the intermediate layer 8, and the press molding can be performed. Since the molded product can be obtained by performing once, there is an effect that a molded product of excellent quality can be manufactured with high productivity by a relatively simple facility.

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 thermoplastic resin molding, and more particularly to a method for molding a plate in which an intermediate layer is laminated with a thermoplastic resin in a sandwich form.

[0002]

2. Description of the Related Art As a method for producing a reinforced resin molded body in which a glass fiber mat or the like is used as an intermediate layer and thermoplastic resin is laminated on both sides in a sandwich shape, a method of supplying a molten resin from both sides of the intermediate layer and pressing it is a method. However, this requires a resin supply device for both the upper mold and the lower mold, and has a drawback that the device becomes more and more complicated when the number of intermediate layers is two.

According to Japanese Unexamined Patent Publication No. 61-152417, an intermediate layer having a small hole through which a molten thermoplastic resin can penetrate is fed into a mold, and then the molten resin is provided above or below the intermediate layer. Has been proposed to obtain a sandwich-shaped laminated molded body by supplying the same and press molding. JP-A-1
No. 178416, an intermediate layer having a hole larger than a molten resin supply port is placed on a lower mold, the molten resin is supplied onto the intermediate layer through the hole, press molding is performed, and then the molten resin is Is proposed between the intermediate layer and the lower mold and press-molded again to produce a laminate.

[0004]

According to the method described in the above-mentioned Japanese Patent Laid-Open Publication, in the former case, a large number of small holes must be provided in the intermediate layer, which lowers the strength of the molded body and also the two intermediate layers. When inserting, it is difficult to adjust the amount of resin on the upper surface, the interlayer portion, and the lower surface. In the latter case, press molding, insertion of the intermediate layer and resin supply must be repeatedly carried out, and there is a drawback that the molding cycle becomes long. In the latter method, when the intermediate press molding is omitted and molding is performed only once in the final step, as shown in FIG. 3, for example, as shown in FIG.
The resin amount 9'on the lower surface is not uniform, and the intermediate layer 8'is also curved.

The object of the present invention is to solve the above-mentioned drawbacks,
It is easy to adjust the amount of resin on the upper surface, the lower surface, or the interlayer portion, and moreover, a multilayer laminated molding is molded by one press molding.

[0006]

The present invention has been made to achieve the above-mentioned object, and in press molding of a thermoplastic resin using upper and lower molds, in a lower mold,
Use a mold that has a tubular protrusion that can project and retract and that has a resin supply port inside the tubular protrusion.With the mold open, project the protrusion and make a hole in part. After inserting the punched insertion intermediate layer into the hole, place it on the mold, supply a fixed amount of molten resin from the resin supply port, and then pull the projection below the mold surface. The method for producing a thermoplastic resin molded body is characterized in that a fixed amount of molten resin is supplied from a resin supply port, the mold is closed, and pressure is applied to mold.

The tubular protrusion is provided on the lower mold, and can protrude from the mold surface into the cavity and can be retracted below the mold surface. The upper and lower parts of the tubular mold can operate hydraulic cylinders, pneumatic cylinders or gears. Operated by. The shape of the tubular protrusion is usually elliptical, although its cross section is usually circular.
It may be square or some other variant. Its inner diameter is
As long as it surrounds the resin supply port, it is preferable that the hole be small in the insertion intermediate layer.

A molten resin supply port is provided in the tubular protrusion and is connected to the molten resin supply device through a resin passage. The resin supply device consists of an extruder and an accumulator. The extruder melts the thermoplastic resin and accumulates it in the accumulator.
The molten resin is pushed out of the resin supply port into the cavity. The resin passage is provided with a temperature adjusting heater so as to maintain a constant temperature.

The insertion intermediate layer used in the present invention is for reinforcing a thermoplastic resin, and an inorganic fiber mat, a fiber reinforced resin sheet, a metal plate or the like is used. The intermediate layer has a hole for penetrating the tubular protrusion. The smaller the hole, the better in the range of penetrating the tubular protrusion. This is because it is better that less resin moves through this hole during press molding.

The thermoplastic resin used in the present invention is one that is melted and softened by heating and hardened by cooling, and may be a resin generally used for press molding. For example, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinylidene fluoride, polyphenylene sulfide, polyphenylene oxide, polyether sulfone, polyether ether ketone and the like can be used.

Further, a copolymer, a graft polymer or a blend resin containing such a resin as a main component can also be used. For example, ethylene-vinyl chloride copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl chloride copolymer, urethane-vinyl chloride copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic acid-modified polypropylene, malein. Examples include acid-modified polyethylene.

The thermoplastic resin contains a stabilizer,
Lubricants, processing aids, additives such as plasticizers and colorants, inorganic fillers such as talc, mica and calcium carbonate, reinforcing materials such as carbon fiber and glass fiber, and foaming to prevent sink marks and warpage. The agent may be blended.

In the present invention, the mold having the above-mentioned structure is used. First, with the mold opened, the tubular projection is raised to project from the mold surface. Then, the insertion intermediate layer is held in the hole by penetrating the tubular protrusion and leaving a gap between the insertion intermediate layer and the mold surface. Then, the resin supply device is operated to extrude the molten thermoplastic resin by a predetermined amount from the resin supply port. Next, pull the tubular protrusion to the mold surface, and again in that state,
A fixed amount of the melted thermoplastic resin is extruded from the resin supply port.

When there are two intermediate layers, the two layers are held at regular intervals, the resin is first supplied to the outside of the two layers, and then the tip of the tubular protrusion is provided between the two layers. Is moved to supply the resin between the two layers, and finally the resin is supplied to the inside of the two layers. The resin may be supplied by temporarily stopping the tubular protrusion at a predetermined position, or may be supplied while moving. Immediately after the resin is supplied, the mold is closed and pressure is applied to perform molding. When closing the mold, the tubular protrusion should not protrude into the mold surface. After that, the mold is cooled, the mold is opened, and the molded body is taken out.

[0015]

In the method for producing a thermoplastic resin molded article of the present invention, the molten resin can be supplied to the upper side, the lower side of the intermediate layer or the interlayer portion of the insertion intermediate layer in a required amount by moving the tubular protrusion. Moreover, the press-molding can be performed once to obtain a molded body.

[0016]

EXAMPLES The method for producing a thermoplastic resin molding of the present invention will be specifically described with reference to examples. FIG. 1 is a cross-sectional view showing the vicinity of the resin supply port. FIG. 2 shows two insertion intermediate layers.
It is sectional drawing of a metal mold | die in the case of molding the laminated board which carried out layer insertion, and FIG. 2a shows the state which has opened the metal mold | die and is supplying the resin to the upper surface of the insertion / insertion intermediate layer. 2B shows a state in which resin is being supplied to the interlayer portion of the two insertion intermediate layers, and FIG.
c shows a state where resin is supplied to the lower surface of the insertion intermediate layer, and FIG. 2d shows a state where the mold is closed and pressure is applied.

Referring to FIG. 1, a main part of a mold used in the present invention will be described. 2 is a lower mold of a press molding machine.
Is a tubular protrusion and is connected to a hydraulic cylinder 6 for moving the protrusion 3 up and down. A molten resin supply port 4 is connected to a resin supply device through a supply passage 5. Although not shown, the resin supply device is composed of an extruder and an accumulator. The resin passage 5 is kept warm by a temperature control heater 7. Reference numeral 8 is an insertion intermediate layer, and 10 is a hole formed in the insertion intermediate layer 8.

FIG. 2 shows a laminated plate in which polypropylene resin is used as the thermoplastic resin and two black unidirectional glass fiber reinforced polypropylene sheets are inserted as the insertion intermediate layer. Here, the unidirectional glass fiber reinforced polypropylene sheet is obtained by uniformly adhering a powdery polypropylene resin containing 1 part by weight of carbon black to filament glass fibers aligned in one direction and melting it with a heating pinch roll. The thickness is 1.2m
It is a sheet of m, 300 mm in length, and 300 mm in width. The glass fiber content is 65% by weight. A hole having a diameter of 5.5 mm is formed in the center of this sheet.

In the case of molding a laminated plate using the resin and the insertion intermediate layer in the mold having the above structure, first, the mold of the press molding machine is opened, the hydraulic cylinder 6 is operated, and the tubular protrusion 3 is 25 mm. Make it protrude. The outer diameter of the tubular protrusion is 5 mm. At this time, the molds 1 and 2 circulate a heat medium to adjust the temperature to 70 ° C. Also, the resin passage 5
Is maintained at 230 ° C. by the temperature control heater 7.
Next, two unidirectional glass fiber reinforced polypropylene sheets 8 are placed on the lower mold 2 in a state where the projecting portions 3 penetrate the holes 10. Then, the two insertion intermediate layer sheets are held so that the distance between the lower mold 2 and the lower insertion intermediate layer sheet 8 is 10 mm and the distance between the insertion intermediate layer sheets 8 and 10 is 10 mm. The distal end of the tubular protruding portion 3 has an upper insertion intermediate layer sheet 8
Slightly protruding on the upper surface of.

Then, the accumulator of the resin supply device is operated to send the molten resin through the resin passage 5 into the mold. The resin 9 sent from the resin supply device is 195
g, from the resin supply port 4 through the inside of the tubular protrusion 3,
The sheet is delivered onto the upper insertion intermediate layer sheet 8. This state is shown in FIG. 2a.

Next, the tubular protrusion 3 is lowered by 12 mm,
The tip is located between the two insertion intermediate layer sheets 8, 8. Subsequently, the accumulator is operated to inject 195 g of the molten resin into the interlayer portion of the two insertion intermediate layer sheets 8 and 8. This state is shown in FIG. 2b. Furthermore,
The tubular protruding portion 3 is lowered until its tip is flush with the cavity surface, and the accumulator is operated to feed 195 g of molten resin between the insertion intermediate layer sheet 8 and the lower mold 2. This state is shown in FIG. 2c.

Immediately after the resin supply was completed, the mold was closed,
It is cooled to 90 ° C. while being pressurized with a pressure of 50 kgf / cm ² . This state is shown in FIG. 2d. The molding cycle time was 180 seconds. The thickness of the laminate thus obtained was 9.6 mm. Then, the front surface and the back surface are coated with polypropylene resin, and when the cross section is observed, the black unidirectional glass fiber reinforced polypropylene sheet and the polypropylene layer form 5 layers which are alternately laminated and are firmly fused to each other. Was there.

[0023]

As described above, in the method of the present invention, the upper side of the insertion intermediate layer to be inserted is
The amount of resin supplied to the lower side or its interlayer can be adjusted,
In addition, a multi-layer laminated plate can be molded by performing the press molding process only once, which is an excellent manufacturing method in terms of quality and productivity.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a press die used in the present invention.

FIG. 2 is a cross-sectional view of a mold for molding a laminated plate in which two insertion intermediate layers are inserted in the present invention.
“A” shows a state in which the mold is opened and the resin is supplied to the upper surface of the insertion intermediate layer. 2b shows a state where resin is being supplied to the interlayer portion of the two insertion intermediate layers, and FIG. 2c shows a state where resin is being supplied to the lower surface of the insertion intermediate layer.
Indicates a state in which the mold is closed and pressure is applied.

FIG. 3 is a cross-sectional view of a laminated plate which has a molding failure in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper mold 2 Lower mold 3 Tubular protrusion 4 Resin supply port 5 Resin passage 6 Hydraulic cylinder 7 Temperature adjusting heater 8, 8'Insertion intermediate layer 9, 9 'Thermoplastic resin 10, 10' Hole in insertion intermediate layer

Claims (1)

[Claims] 1. In press molding of a thermoplastic resin using upper and lower molds, a lower mold is provided with a tubular protrusion capable of protruding and retracting from a lower mold surface, and a resin supply port is provided in the tubular protrusion. Using the mold provided with, the projecting part is projected with the mold open, and the insertion intermediate layer with a hole in part is placed on the mold by penetrating the projecting part into the hole. Then, a fixed amount of molten resin is supplied from the resin supply port, then the protrusion is pulled below the mold surface, and then a fixed amount of molten resin is supplied from the resin supply port, then the mold is closed and pressurized. A method for producing a thermoplastic resin molded body, which comprises shaping.