JPH02160510A - Production of fiber reinforced composite - Google Patents

Abstract

PURPOSE:To obtain a fiber reinforced composite having excellent strength by holding powdery thermoplastic resin between the filaments of roving-shaped reinforced fiber and heating the filaments at the temp. not lower than the m.p. of the resin and thereafter passing the filaments through a plurality of dies having the passage ports different in the cross-sectional shapes and cooling the filaments. CONSTITUTION:Reinforced fiber 1 is guided by the guide rolls 22, 23, 24 and introduced into a vessel 20. Powdery thermoplastic resin 2 in the vessel 20 is held between the filaments. At this time, a fluidized bed 26 is formed by ejecting gas into the vessel 20 through the air holes 25. Successively, reinforced fiber 1 holding resin 2 is supplied to a far infrared heating oven 60 and heated. Thereafter reinforced fiber 1 is passed through a first die 61 and the cross-sectional shape is made a square and then passed through a second die 62 and the cross-sectional shape is made a circular form. Furthermore, even when reinforced fiber 1 is passed through a third die 63, it is subjected to the same action and thereafter it is passed through the pinch rolls and cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a fiber reinforced composite material in which reinforcing fibers and a thermoplastic resin are integrated.

(Prior technology) Continuous reinforcing fibers in the form of roving are passed through a powdered thermoplastic resin, the reinforcing fibers retain the powdered thermoplastic resin, and then continuously passed through a heating zone to form a powder. BACKGROUND ART A method for producing a fiber-reinforced composite material in which reinforcing fibers and a thermoplastic resin are integrated by melting a thermoplastic resin and then passing it through a heated mold is widely known.

That is, in the conventional manufacturing method, a heated mold having a passage opening with a desired cross-sectional shape is placed at a rear position of a heating zone, and after melting the powdered thermoplastic resin in the heating zone,
A fiber-reinforced composite material having a desired cross-sectional shape is obtained by passing the reinforcing fibers to which the molten resin has adhered through the passage hole of the mold.

In the conventional method, a fiber-reinforced composite material in which filaments of reinforcing fibers are aligned in one direction can be obtained. However, because the molten thermoplastic resin does not penetrate sufficiently between the filaments of the reinforcing fibers, there is a drawback that the adhesion between the thermoplastic resin and the reinforcing fibers is poor, and the manufactured fiber-reinforced composite material may be brittle. was there. In addition, when integrating a resin composition made by adding stabilizers, lubricants, etc. to powdered thermoplastic resin into reinforcing fibers, the dispersibility of the additives is poor and the effects of the additives cannot be fully demonstrated. There were drawbacks.

As a technique for improving the adhesion between the resin and reinforcing fibers by imparting shear flow to the resin, JP-A-50-35460 discloses a technique in which the cross-sectional area of the passage opening of the mold is reduced to allow molten resin to adhere. A method is disclosed for squeezing out excess resin when the reinforcing fibers pass through this passage port. however,
This method has the disadvantage that the resin tends to remain in the mold, leading to the problem of resin deterioration.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned drawbacks, and its purpose is to provide a structure in which the filaments of reinforcing fibers are aligned in one direction and have sufficient flow between the filaments. An object of the present invention is to provide a method for producing a fiber-reinforced composite material impregnated with a thermoplastic resin and having excellent strength.

(Means for Solving the Problems) The method for producing a fiber-reinforced composite material of the present invention involves passing a roving-shaped reinforcing fiber made up of a large number of continuous filaments through a powdered thermoplastic resin to create a fiber-reinforced composite material between the filaments. After holding the thermoplastic resin in powder form, the thermoplastic resin is heated to a temperature higher than the melting temperature of the thermoplastic resin to melt the thermoplastic resin, and a mold having a passage opening with a different cross-sectional shape depending on the molten state of the thermoplastic resin is formed. The feature is that a plurality of particles are passed through and then cooled, thereby achieving the above object.

FIG. 1 shows an example of a manufacturing apparatus used in the present invention.

This manufacturing device includes an unwinding roll 10 for setting a roll 1a wound with roving-shaped reinforcing fibers 1, a container 20 in which powdered thermoplastic resin 2 is supplied, and a container 20.
a pinch roll 11 that takes over the reinforcing fiber 1 that has passed through the
The reinforcing fibers 1 are placed on the way to being taken up by the vinyl rolls 11, and a pair of press rolls 40 are placed on the upper and lower surfaces of the reinforcing fibers 1 to press and spread the reinforcing fibers 1 to a certain width. A slitter 50 that removes the excess powdered thermoplastic resin 2 retained in the resin 1 to keep the retained amount constant.
．． 51, a far-infrared heating furnace 60 for melting the powdered thermoplastic resin 2 held on the reinforcing fibers 1, and heating to integrate the molten thermoplastic resin and the reinforcing fibers 1 and form a predetermined cross-sectional shape. It is equipped with molds 61, 62, and 63 in the state.

The bottom of the container 20 has a large number of ventilation holes 25, 25...
is provided, and the gas sent from the gas supply path 21 is sent into the container 20 through the vent hole 25. Therefore, the thermoplastic resin powder 2 placed in the container 20 is fluidized by the jetting of the gas, and a fluidized bed 26 is formed. Guide rolls 22, 23, 24 for guiding the reinforcing fibers 1 are arranged at the upper end and inside the wall of the container 20.

The shape of the passage port through which the reinforcing fiber 1 of the mold 61, 62, 63 passes is different for each mold 61, 62, 63. For example, the passage port of the first mold 61 on the heating furnace 60 side The cross-sectional shape of the passage hole of the second mold 62 is formed as a circle, and the cross-sectional shape of the passage hole of the third mold 63 is formed as a rectangle.

The cross-sectional area of the passage opening of each mold 61, 62, 63 is preferably set to be approximately equal to or slightly larger than the cross-sectional area of the reinforcing fiber 1 to which the molten resin is attached. It is preferable to gradually reduce the cross-sectional area of the passage opening as the third mold 63 is approached.

The cross-sectional shapes of the passage openings of the first to third molds 61, 62, 63 can be changed in various ways, for example, they may be rhombic, trapezoidal, oval, etc. 6
The cross-sectional shape of the passage port No. 3 is made different. Also,
Even if the cross-sectional shape of the passage hole is the same shape other than circular, the angle of the passage hole may be changed. For example, the first and third molds 61 and 63 have a vertically long rectangle, and the second mold has a vertically long rectangle. Each mold 61.62 may be a horizontally long rectangle.
The heating temperature of 62.63 is preferably set to approximately the melting point or higher than the melting point of the powdered thermoplastic resin 2, and four or more molds may be provided.

Next, the manufacturing method of the present invention will be explained using the above manufacturing apparatus.

The ends of the reinforcing fibers 1 are pinched by pinch rolls 11, and the reinforcing fibers 1 are taken off at a predetermined speed by the rotational drive of the pinch rolls 11 and sequentially rewound from the outside of the rolls 1a without being twisted. The reinforcing fibers 1 are then guided by guide rolls 22, 23, 24 into the container 20. A powdered thermoplastic resin 2 is placed in a container 20, and the powdered thermoplastic resin 2 enters between the filaments of the reinforcing fibers 1 passing through the container 20 and is held therein. In particular, as described above, by ejecting gas from the vent hole 25 into the container 20 to form the fluidized bed 26, the reinforcing fibers 1 are transformed into filaments by the ejection of gas and the collision of the powdered thermoplastic resin 2. It becomes easier to open the fibers into shapes,
The powdered thermoplastic resin 2 can be easily penetrated between the filaments of the roving. Further, the reinforcing fibers 1 may be mechanically opened within the container 20 using a reinforcing fiber 1 opening device or the like.

Next, the reinforcing fiber 1 holding the powdered thermoplastic resin 2 is spread out into a belt shape of a constant width by passing through the roll 40 while being pressed.
Excess powdered thermoplastic resin 2 is removed when passing through the upper and lower surfaces of 0.51, and the retained amount is kept constant. Subsequently, the reinforcing fiber 1 holding the powdered thermoplastic resin 2 is supplied to a far-infrared heating furnace 60, where it is heated and the powdered thermoplastic resin is melted. After that, when the reinforcing fiber 1 to which the melting resin is attached passes through each mold 61, 62, 63, it is pressed by the inner surface of the passage port of each mold 61, 62, 63, and as a result, the molten resin and the reinforcing fiber 1 are integrated.

That is, the cross-sectional shape of the reinforcing fibers 1 to which the molten resin adheres after passing through the first mold 61 is square, and then when passing through the second mold 62, the reinforcing fibers 1 have a circular cross-section. Since it is forcibly pressed from the inner wall surface of the passage opening of the mold 62, the molten resin is forced into the reinforcing fibers 1, and the molten resin is sufficiently impregnated into the reinforcing fibers 1. Moreover, when the reinforcing fiber 1 to which the resin is attached passes from the second mold 62 to the third mold 63, it is subjected to a similar effect.

Thereafter, it passes through pinch rolls 11 and is cooled, thereby obtaining a plate-shaped fiber-reinforced composite material.

Roving-shaped continuous reinforcing fiber 1 used in the present invention
Inorganic fibers such as glass fibers, carbon fibers, and fine metal wires, and organic fibers such as aramid fibers, polyester fibers, and polyamide fibers are used, and the fiber diameter is usually 2 to 40μ.
It is a continuous fiber composed of several hundred to several dozen m filaments bundled in the same direction. Further, the reinforcing fiber 1 may be subjected to a commonly performed sizing treatment in order to improve the adhesive strength with the resin. In addition, fibers are selected that are thermally stable at the melting temperature of the powdered thermoplastic resin used.

Powdered thermoplastic resins used in the present invention include polyethylene, polypropylene, polyvinyl chloride, polysulfone,
All resins that are softened and melted by heat, such as polyamide, polyvinylidene fluoride, polyphenylene sulfide, and polyetheretherketone, can be used. Mixtures of these thermoplastics may also be used. Also, stabilizers,
Additives such as lubricants, processing aids, plasticizers, dyes, and pigments may be incorporated into the thermoplastic resin. The average particle diameter of this powdery thermoplastic resin is preferably 1000 μm or less.

If the average particle diameter of the powdered thermoplastic resin exceeds 1000 μm, the powder will not flow properly in the fluidized bed, and o-
The adhesion of the thermoplastic resin between the filaments of the hinge-shaped continuous reinforcing fibers tends to decrease.

Furthermore, a fibrous fine filler may be supplied into the container 20 to be held between the filaments of the reinforcing fibers 1 together with the powdered thermoplastic resin 2. As this fine filler, milled inorganic fibers such as glass fibers and carbon fibers, or whiskers such as silicon nitride, silicon carbide, and potassium titanate are preferably used. In this way, by holding the microfiller between the filaments of the reinforcing fibers 1, it is possible to increase the strength between the fibers of the fiber-reinforced composite material manufactured by the randomly oriented microfillers. Cracks along the longitudinal direction can be prevented.

The average aspect ratio (L/D) of this fibrous microfiller is preferably 5 or more. When the average aspect ratio is less than 5, the fibrous function is lost, and the fiber-reinforced composite material cannot have sufficient strength in the width and thickness directions, and the fiber length of the fibrous microfiller is in the range of 10 to 1000 μm. is preferred. When the fiber length exceeds 1000 μm, the powder does not flow properly in the fluidized bed 26, and the fibrous microfiller does not adhere sufficiently between the filaments of the roving-shaped reinforcing fibers 1.

If it is less than 10 μl, the fibrous function is lost, and the fiber-reinforced composite material cannot have sufficient strength in the width and thickness directions.

Further, the fibrous microfiller is preferably contained in the mixed composition 2 of the powdered thermoplastic resin and the fibrous microfiller in a range of 1 to 30% by volume.

If it is less than 1% by volume, the effect of adding the fibrous microfiller is small and the strength in the width and thickness directions of the fiber-reinforced composite material cannot be obtained sufficiently, and if it exceeds 30% by volume, the bonding strength of the thermoplastic resin decreases. However, the impregnation of the thermoplastic resin into the reinforcing fibers 1 tends to be impaired.

Air is normally used as the gas for forming the fluidized bed 26, and is supplied from a compressor, blower, or the like. An inert gas such as nitrogen, carbon dioxide, helium, or argon is used as necessary.

The fiber reinforced composite material obtained by the present invention has reinforcing fibers 1
Because the filaments constituting the fiber are oriented in one direction in an open state, they have high strength in the bending direction, and also have passage ports with different shapes when the powdered thermoplastic resin is molten. Since it is pressed from a plurality of molds, the molten resin and the reinforcing fibers are in close contact with each other, and the adhesion between the fibers is also good, resulting in a fiber-reinforced composite material with high strength.

The fiber-reinforced composite material thus obtained can be molded into various shapes, and can be used alone, in a stack of multiple sheets, or in a stack with other members to make plates, pipes, etc.

(Example) The present invention will be explained in detail below based on examples.

501 Materials Used> Seven glass fiber rovings (filament diameter 22 μm, (4400 g/km)) were used as the reinforcing fibers. As the powdered thermoplastic resin, a mixture of the following composition was used.

Butyltin sulfur-containing stabilizer (Sankyoki Co., Ltd., ST, ANN-JP95B)...
3 parts by weight Stearyl alcohol 1 part by weight Polyolefin wax 1 part by weight Manufacturing conditions> A plate-shaped fiber-reinforced composite material was manufactured using the apparatus shown in FIG. The powdered thermoplastic resin 2 was put into the container 20, and air was blown into the container 20 through the vent hole 25 at the bottom of the container 20 using a compressor to form a fluidized bed 26.

The pick-up speed of the roving 1 is as follows:
The speed was set at a constant speed of 150 cm/11 inch. The heating furnace 60 used had an infrared heater set at a surface temperature of about 340°C. The passage length of the reinforcing fibers 1 through the passage ports of each mold 61, 62, and 63 was 100 mm, and the temperature was 190°C. The cross-sectional shape of the passage opening of the first mold 61 is a square with a side of 7.8 mm, the cross-sectional shape of the passage opening of the second mold 62 is circular with a diameter of 8.8 mm, and the cross-sectional shape of the passage opening of the second mold 62 is a circle with a diameter of 8.8 mm. The cross-sectional shape of the passage port is 2.0 mm long.
, a rectangle with a width of 30 mm.

The obtained plate-shaped fiber reinforced composite material had a width of about 30 mm and a thickness of about 2 mm, the glass fiber content was 30% by weight, the filaments were oriented in one direction, and the resin was well impregnated between the filaments. . When the resulting fiber-reinforced composite material was subjected to a bending test and a DuPont impact test, the bending strength was 35 kg/mm2, and the impact strength was 45 kg-cm.
Met.

<Manufacturing Conditions> In the apparatus shown in FIG. is a square with one side of 7.8M, and the cross-sectional shape of the passage hole of the third mold 63 is 2.0M in length and 30M in width.
A plate-shaped fiber-reinforced composite material was obtained in the same manner as in Example 1 except that it was made into a rectangle of mm.

The obtained plate-shaped fiber reinforced composite material had a width of about 30 mm and a thickness of about 2 mm, the glass fiber content was 30% by weight, the filaments were oriented in one direction, and the resin was well impregnated between the filaments. .

When the resulting plate-shaped fiber-reinforced composite material was subjected to a bending test and a DuPont impact test, the bending strength was 35 kg/mm.
The impact strength was 40 kg-cm.

Back layer ■Yu <Manufacturing conditions> Ten PAN-based carbon fiber roving filaments (diameter: 8 μm, number of filaments: 6000) were used as reinforcing fibers. Polyvinylidene fluoride (degree of polymerization: 1100, average particle diameter: 200 μm) was used as the powdered thermoplastic resin.

Manufacturing Conditions> Using the same apparatus as in Example 1, a plate-shaped fiber reinforced composite material was manufactured under the following conditions. The take-up speed of the roving 1 was set to a constant speed of 120 cm/win by the pinch roll 11. The heating furnace 60 was equipped with an infrared heater whose surface temperature was set to about 350°C.

The passage length of the reinforcing fibers 1 through the passage ports of each mold 61, 62, and 63 was 100 m+, and the temperature was 210°C.

The cross-sectional shape of the passage opening of the first mold 61 is a square with a side of 7.8 mm, and the cross-sectional shape of the passage opening of the second mold 62 is a diameter of 8 mm.
．． The cross-sectional shape of the passage opening of the third mold 63 was a rectangle with a length of 2.0 mm and a width of 30 mm.

The obtained plate-shaped fiber-reinforced composite material has a width of about 30 mm and a thickness of about 2 mm.
InL11, the glass fiber content was 20% by weight, the filaments were oriented in one direction, and the resin was well impregnated between the filaments.

When the resulting plate-shaped fiber-reinforced composite material was subjected to a bending test and a DuPont impact test, the bending strength was 40 kg/mB.
The impact strength was 50 kg-cm.

Comparison 1 ■ <Manufacturing conditions> In the fiber-reinforced composite material manufacturing apparatus shown in FIG.
A plate-shaped fiber-reinforced composite material was obtained in the same manner as in Example 1, except that only the following materials were used.

The obtained plate-shaped fiber-reinforced composite material has a width of about 30 mm, a thickness of about 211I111, and a glass fiber content of 40% by weight.
Although the filaments were oriented in one direction, the resin was not sufficiently impregnated between the filaments.

When the resulting plate-shaped fiber-reinforced composite material was subjected to a bending test and a DuPont impact test, the bending strength was 12 kg/mm.
The impact strength was 6 kg-ctt+.

(Effects of the Invention) As described above, according to the manufacturing method of the present invention, the filaments of the reinforcing fibers are aligned in one direction, the resin is sufficiently impregnated between the filaments, and the fibers have excellent bending strength and impact resistance. A reinforced composite material can be obtained. Moreover, there is no need to particularly reduce the cross-sectional area of the passage opening of the mold, and there is no possibility that the molten resin will stay in the mold and deteriorate the resin as in the prior art.

4. Figure 1 is a schematic diagram showing an embodiment of the manufacturing apparatus used in the present invention.

1... Reinforcing fiber, 2... Powdered thermoplastic resin, 61
...First mold, 62...Second mold, 63...
Third mold.

Claims (1)

[Claims] 1. After passing a roving-shaped reinforcing fiber composed of a large number of continuous filaments through a powdered thermoplastic resin and holding the powdered thermoplastic resin between the filaments, the melting temperature of the thermoplastic resin is Production of a fiber-reinforced composite material characterized in that the thermoplastic resin is melted by heating above, and the molten thermoplastic resin is passed through a plurality of molds having passage ports with different cross-sectional shapes, and then cooled. Method.