JPH06328482A - Manufacture of fiber reinforced thermoplastic resin molded body - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a fiber reinforced thermoplastic resin molded body having a high strength and excellent appearance by using fiber composite sheets wherein fibers have already been jointed by a thermoplastic resin. CONSTITUTION:Two fiber composite sheets 8 wherein fibers have been jointed by a thermoplastic resin of 10-80wt.% are superposed and arranged in a cavity 11 of a lower mold 10 of a compression mold 9 whose temperature is adjusted. An outlet 12 of a movable extruder is moved on the fiber composite sheets 8, while a melted homopolypropylene is supplied from a nozzle 13. An upper mold 15 is made to descend and opened at about 100kg/cm<2>, cooled to a product temperature of about 70 deg.C with pressure, and a molded body 16 on a plane plate is taken out. Thus, a product having a high strength can be obtained by melting a fiber jointing thermoplastic resin and a supplying thermoplastic resin. As a thermoplastic resin layer is formed on the surface of the molded body, a product having excellent appearance 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 producing a fiber-reinforced thermoplastic resin molding.

[0002]

2. Description of the Related Art As a method for producing a fiber-reinforced thermoplastic resin molded article, (a) a method in which a fibrous sheet is placed in a mold and then a molten thermoplastic resin is injected to solidify it is known (Japanese Patent Application Laid-Open No. 2000-242242). See Japanese Patent Laid-Open No. 63-199620). Also,
(B) A method of heating and press-molding a stampable sheet made of a fiber reinforced thermoplastic resin is also known.

[0003]

However, the method (a) has a problem that the strength of the molded product is not sufficient because the molten thermoplastic resin does not sufficiently penetrate between the fibers or even at the fiber intersections. However, the method (b) has a problem that the fibers stand out on the surface of the molded product and the appearance is poor.

It is an object of the present invention to provide a method for producing a fiber-reinforced thermoplastic resin molding having high strength and good appearance.

[0005]

In order to achieve the above-mentioned object, the method for producing a fiber-reinforced thermoplastic resin molded product according to the present invention is such that fibers are bonded with a thermoplastic resin of 10 to 80% by weight. The composite sheet is arranged in the mold in a state of being heated to a temperature higher than the melting temperature of the fiber-bonding thermoplastic resin, and then the molten thermoplastic resin is supplied into the mold to close the mold. .

Examples of the fiber include glass fiber, carbon fiber, silicon / titanium / carbon fiber, boron fiber, fine metal fiber, aramid fiber, polyester fiber, polyamide fiber and the like. The diameter of the monofilament is preferably 1 to 50 μm, particularly preferably 3 to 23 μm. The fiber length is appropriately determined depending on the performance and shape required of the product, but is preferably 5 mm or more. If it is less than 5 mm, the reinforcing effect of the fiber is not sufficient. In addition, continuous fibers may be used.

As the thermoplastic resin for fiber joining and the thermoplastic resin to be supplied, all resins which are melted and softened by heating can be used. For example, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinylidene fluoride, polyphenylene sulfide, polyphenylene oxide, polyether sulfone, polyether ether ketone, etc. are used. Further, copolymers or graft resins or blend resins containing the above thermoplastic resin as a main component, for example, ethylene-vinyl chloride copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl chloride copolymer, urethane-chloride. Vinyl copolymers, acrylonitrile-butadiene-styrene copolymers, acrylic acid-modified polypropylene, maleic acid-modified polyethylene and the like can also be used. The thermoplastic resin may be blended with additives such as a stabilizer, a lubricant, a processing aid, a plasticizer and a colorant, and a filler such as talc, mica and calcium carbonate. Further, it is preferable that the fiber-bonding thermoplastic resin and the supplied thermoplastic resin are of the same type from the viewpoint of reliable fusion between the two resins.

The fiber composite sheet preferably has a large number of voids and no thermoplastic resin layer on the surface from the viewpoint of easy penetration of the supplied thermoplastic resin, but the stampable sheet also releases pressure when the sheet is heated. As a result, the fibers are napped and can be used. The content of the thermoplastic resin in the fiber composite sheet needs to be 10 to 80% by weight. If it is less than 10% by weight, the fusion with the supplied thermoplastic resin is not sufficient, and if it exceeds 80% by weight, the strength of the fiber composite sheet itself is weak and the fiber content rate relative to the product weight is small, so that it is obtained. The strength of the product is weakened.

Examples of the heating method for bringing the thermoplastic resin of the fiber composite sheet into a molten state include a method using a heating furnace, hot air, and a far infrared heater. The heating of the fiber composite sheet may be performed outside the mold, and then the fiber composite sheet may be placed inside the mold, or may be performed on the fiber composite sheet placed inside the mold. It should be noted that heating accompanied by pressurization, such as pressing a hot plate or passing between heating rolls, is not suitable because the permeation of the supplied thermoplastic resin into the fiber composite sheet may deteriorate.

Since the mold closing must be performed before the supplied thermoplastic resin has cooled to a temperature lower than the melting temperature, it is preferably carried out immediately after the supply of the molten thermoplastic resin. Further, the mold closing force is appropriately adjusted by the viscosity of the thermoplastic ^{resin, 50kg / cm 2 ~150kg / cm} 2 is preferably about.

The lower the viscosity of the supplied thermoplastic resin is, the more easily it penetrates into the fiber composite sheet. Therefore, the melt flow rate at the molding temperature is preferably 20 g / 10 minutes or more.

When a product having a particularly good appearance is required, the molten thermoplastic resin must be supplied to the side of the surface having a good appearance. When it is desired to obtain a product having good appearance on both sides, the molten thermoplastic resin may be supplied to both sides of the fiber composite sheet.

A heated fibrous sheet is placed on the molten thermoplastic resin supplied from the nozzle of the movable extruder, and the molten thermoplastic resin is further supplied from the extruder. Alternatively, the molten thermoplastic resin is injected and supplied from both sides of the heated fibrous sheet.

[0014]

In the method for producing a fiber-reinforced thermoplastic resin molding according to the present invention, a fiber-composite sheet in which fibers are bonded with 10 to 80% by weight of a thermoplastic resin is melted in a mold. It is placed in a state of being heated to a temperature equal to or higher than the temperature, and then the molten thermoplastic resin is supplied into the mold to close the mold, so that the fiber-bonding thermoplastic resin and the supplied thermoplastic resin are fused and the product. A thermoplastic resin layer is formed on the surface of the molded body.

[0015]

EXAMPLES Examples of the present invention will be described below with reference to the drawings and in comparison with comparative examples.

Example 1 First, an apparatus used for producing the fiber composite sheet used in the present invention will be described.

In FIG. 1, the front means the right side, and the rear means the left side.

The composite sheet manufacturing apparatus (1) shown in FIG. 1 includes upper and lower endless belts (2) and (3) and two endless belts (2) and (3) which are opposed to each other with a distance of 20 mm. It is equipped with a heating device (4) consisting of an infrared heater arranged so as to sandwich it from above and below the opposite transfer parts (2a) (3a) of the lower endless belt (3) and the upper endless belt (2). Both endless belts are made to project further rearward, and the rearward extension of the transfer part (3a) is a double endless belt.
(2) It is formed as a feeding part (3b) into the gap of (3).

The two endless belts (2) and (3) are driven substantially continuously in the same direction by driving one of the upper and lower pulleys (5) and (6) respectively by a motor (not shown). It is designed to move at the same speed. Also, the rear part of the transfer part (2a) of the upper endless belt (2) is inclined rearward and upward,
The gap between the upper and lower transfer portions (2a) and (3a) widens rearward. The upper and lower endless belts (2) and (3) are made of a fiber cloth reinforced Teflon sheet having a thickness of 0.3 mm.

Next, glass fibers having a diameter of 23 μm and a length of 30 mm and powdered homopolypropylene having a particle diameter of 150 μm were mixed so that the content of the homopolypropylene was 40% by weight, and this mixture (7) was mixed. It is supplied onto the feeding part (3b) of the fiber composite sheet manufacturing apparatus (1). Then, as the upper and lower endless belts (2) and (3) move, the mixture (7) passes through the heating area by the heating device (4) while being lightly sandwiched by the transfer sections (2a) and (3a), and the heat is removed. The plastic resin melts and penetrates between the fibers. After the mixture (7) has passed through the heating zone, the mixture (7)
Is cooled, length 300 mm, width 200 mm, thickness 20 m
A fiber composite sheet (8) having a weight of 50 m and a weight of 50 g was obtained.

The particle size of the above-mentioned powdery homopolypropylene is 150 μm, but generally the particle size is 10 to 300 μm.
Those within the range of m are suitable.

After heating the above fiber composite sheet (8) to about 230 ° C. in an electric oven, as shown in FIG. 2, two sheets are laminated and the temperature is adjusted to 60 ° C. under the compression molding die (9). Mold (10)
It is placed in the cavity (11) of the extruder, and then the movable extruder discharge port (12) is moved over the fiber composite sheet (8) while the homopolypropylene (melt melt) is melted from the nozzle (13). Flow rate 70g / 10 minutes) 1200g (14)
Is immediately supplied, and the upper mold (15) is immediately lowered to 100 kg / c.
The mold is closed at m ² , and the product is cooled to 70 ° C. while being pressurized, and the product is a flat plate-shaped product as shown in FIG.
(16) was taken out.

The overall thickness of this molded body (16) is 20.5 mm.
Then, the thermoplastic resin layer (18) having a thickness of 2.5 mm was integrally formed on the fiber-reinforced thermoplastic resin layer (17) having a thickness of 18 mm.

Example 2 A fiber reinforced thermoplastic resin sheet composed of continuous glass fiber strands and polypropylene (Azudel manufactured by Ube Nitto Kasei)
Polypropylene content 60% by weight) was heated to 230 ° C. with a far infrared heater and then compression molded to obtain a fiber composite sheet having a length of 300 mm, a width of 200 mm, a thickness of 2 mm and a weight of 100 g.

The above fiber composite sheet was molded in the same manner as in Example 1 to obtain a flat plate-shaped molded body.

The overall thickness of this molded body is 21.0 mm,
8m thickness on 13mm thick fiber reinforced thermoplastic resin layer
m thermoplastic resin layer was integrally formed.

Example 3 The polypropylene resin supplied had an MFR of 9.0 g / 10.
Same as Example 1 except minutes.

Comparative Example 1 A glass fiber having a diameter of 23 μm and a length of 30 mm wetted with polyvinyl alcohol, and a powdery homopolypropylene having a particle size of 150 μm were used.
The mixture was mixed so as to be 7% by weight, and a length of 300 was obtained from this mixture by using the fiber composite sheet manufacturing apparatus as in Example 1.
A fiber composite sheet having a size of mm, a width of 200 mm, a thickness of 9 mm and a weight of 30 g was obtained.

A flat plate-shaped molded product was obtained in the same manner as in Example 1 except that this fiber composite sheet was used and the amount of molten homopolypropylene supplied was 1220 g.

The total thickness of this molded body is 21.5 mm,
16. A thickness of 16 on the fiber-reinforced thermoplastic resin layer having a thickness of 5 mm.
A 5 mm thermoplastic resin layer was integrally formed.

Comparative Example 2 A flat plate-shaped molded product was obtained in the same manner as in Example except that the fiber composite sheet used in Example 1 was placed in the cavity of the lower mold without heating.

The total thickness of this molded body is 23.5 mm,
3. A thickness of 4 on a fiber-reinforced thermoplastic resin layer having a thickness of 19 mm.
A 5 mm thermoplastic resin layer was integrally formed.

Comparative Example 3 Glass fiber having a diameter of 23 μm and a length of 30 mm and a particle size of 15
A powdery homopolypropylene of 0 μm was mixed so that the content of the homopolypropylene would be 90% by weight, and from this mixture, a fiber composite sheet manufacturing apparatus was used in the same manner as in the example to obtain a length of 300 mm, a width of 200 mm and a thickness A fiber composite sheet having a size of 16 mm and a weight of 50 g was obtained.

A flat plate-shaped molded product was obtained in the same manner as in Example 1 except that this fiber composite sheet was used.

The total thickness of this molded body is 22.5 mm,
The thermoplastic resin layer having a thickness of 7 mm was integrally formed on the fiber-reinforced thermoplastic resin layer having a thickness of 15.5 mm.

A three-point bending test was conducted on the molded articles obtained in the above-mentioned Examples and Comparative Examples. The three-point bending test
According to JIS-K7055 Bending test method for fiber reinforced plastics. Further, the appearance of the molded body on the side to which the molten thermoplastic resin was supplied was observed. The appearance was visually inspected for the presence or absence of the protrusion of fibers on the surface.

Comparative Example 4 A fiber reinforced thermoplastic resin sheet made of continuous glass fiber strands and polypropylene resin (Azudel fiber content of Ube Nitto Kasei 40% by weight) was used with a far infrared heater.
After heating to 0 ° C., compression molding was performed to obtain a flat plate-shaped sample having a thickness of 20 mm. The results are shown in Table 1.

[0038]

[Table 1] As is clear from Table 1, the fiber-reinforced thermoplastic resin molded product obtained by the manufacturing method of the present invention is excellent in strength and appearance.

[0039]

According to the method for producing a fiber-reinforced thermoplastic resin molded product of the present invention, since the fiber composite sheet in which the fibers are already bonded with the thermoplastic resin is used, the fiber-bonded thermoplastic resin is used. A high-strength product is obtained in combination with the fusion of the supplied thermoplastic resin, and a thermoplastic resin layer is formed on the surface of the molded product, so that a product with a good appearance is obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an apparatus for manufacturing a fiber composite sheet.

FIG. 2 is a vertical cross-sectional view showing an embodiment of the present invention and showing a state in which a fiber-reinforced thermoplastic resin molded body is being manufactured.

FIG. 3 is a partial perspective view of a fiber-reinforced thermoplastic resin molding obtained by the method of the present invention.

[Explanation of symbols]

 (8): Fiber composite sheet (11): Mold cavity (14): Molten thermoplastic resin (16): Fiber reinforced thermoplastic resin

Claims (1)

[Claims] 1. A fiber composite sheet in which fibers are bonded with 10 to 80% by weight of a thermoplastic resin is placed in a mold in a state of being heated to a melting temperature of the fiber bonding thermoplastic resin or higher, and then a metal A method for producing a fiber-reinforced thermoplastic resin molding, which comprises closing a mold by supplying a molten thermoplastic resin into the mold.