JPH0564810A - Manufacture of fiber reinforced composite material - Google Patents

Abstract

PURPOSE:To obtain long fiber reinforced thermoplastic resin composition, in which no fuzz develops and the adherence between fiber and matrix is excellent, by a method wherein strand is pressed with rolls in the form of ribbon and, after that, shaped by being passed through a shaping nozzle. CONSTITUTION:Continuous reinforcing fiber roving 2 is introduced in molten thermoplastic resin so as to infiltrate the molten resin in the fibers. Next, the resultant roving is continuously drawn out with a drawing device under the condition that excess resin is squeezed out by means of a nozzle. The resultant strand 3 is pressed with rolls 4 in the form of ribbon and, after that, shaped by being passed through a shaping nozzle 5 in order to strand-shaped fiber reinforced composite material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a thermoplastic resin composite material reinforced with long fibers.

[0002]

2. Description of the Related Art In recent years, pultrusion molding has attracted attention as a method for producing a thermoplastic resin composition reinforced with long fibers. Above all, the method of impregnating the melt of the thermoplastic resin in the crosshead die while pulling the continuous reinforcing fiber bundle has the advantages of easy operation and easy control of the fiber content. As a method of this kind, for example, Japanese Patent Publication No. 49-41105 discloses a method of obtaining a long fiber reinforced resin composition by passing a continuous fiber through a crosshead die. Further, US Pat. No. 4,439,387 shows a method of effectively impregnating fibers with a molten resin by corrugating the crosshead. However, the method of impregnating continuous fibers with the melt of the thermoplastic resin by these crossheads has the following problems. First, some fiber inside the crosshead die breaks,
This becomes fluff and adheres to the drawn strands,
Impair the appearance of the product. Secondly, since impregnation cannot be performed completely, although the amount is very small, fibers not impregnated with resin are generated during cutting or hunting of a product. Conventionally, in order to improve the impregnation, the molecular weight of the matrix to be used has been reduced to reduce the melt viscosity, but a molded article made of such a resin composition has a problem that mechanical properties are deteriorated. Was there.

[0003]

SUMMARY OF THE INVENTION In view of the above situation, the inventors of the present invention have long-fiber-reinforced thermoplastic resin composition in which a molten thermoplastic resin is impregnated in a crosshead die while drawing a continuous reinforcing fiber bundle. After solving the above problems in the method for producing a product, without fluffing, as a result of diligent study to obtain a long fiber reinforced thermoplastic resin composition having excellent adhesion between the fiber and the matrix, after the strand obtained by a conventional method is specified. Find that it is effective to apply processing,
The present invention has been completed. That is, the present invention introduces continuous reinforcing fiber roving into a molten thermoplastic resin, impregnates the molten resin with fibers, and continuously while squeezing an excessive amount of resin with a nozzle using a drawing device. The present invention relates to a method for producing a strand-shaped fiber-reinforced composite material, which comprises a drawing step, a step of pressing the strand obtained by this step into a ribbon shape with a roll, and a step of passing the pressed strand through a shaping nozzle to adjust the shape.

Generally, the crosshead die has advantages such as good operability and easy adjustment of the resin content, but on the other hand, the impregnation of the resin into the fiber bundle is not complete,
There is a drawback that the adhesion between the fiber and the matrix is insufficient. It is a feature of the present invention that an advanced product is obtained while taking advantage of such a crosshead die.

In the first step of the present invention, a continuous reinforcing fiber roving is introduced into a molten thermoplastic resin to impregnate the molten resin with fibers, and then an excess amount of the resin is discharged by a nozzle using a drawing device. Is a step of continuously drawing out while narrowing down, and there is no difference in this step from the case of ordinary pultrusion molding.

When the cross section of the strand obtained by the method using the crosshead die is observed, the fiber filaments are often not uniformly distributed, but are distributed in an S-like shape (see FIG. 2). If the impregnation is not sufficient, there will be only resin-free lumps of fibers only.

The second step of the present invention is a step of pressing the strands obtained in the first step into a ribbon shape with a roll, and the roving impregnated with the molten resin is pressed with a roll to obtain a resin. The molten resin can be mechanically impregnated into the fiber bundles that are not in contact with. In the second step, the pressure of pressing by the roll is not particularly limited, but it is preferably performed within the range satisfying the following formula in order to improve the dispersion of glass and the like. b / a = 2-10 (where a is the strand diameter (cm) from the crosshead die,
b is the lateral width (cm) of the pressed ribbon-shaped strand. ) Particularly preferred is when b / a = 2.5 to 4.

The third step of the present invention is a step of adjusting the shape by passing the pressed strand through a shaping nozzle after the second step. When the strand is passed through the shaping nozzle, the roving becomes flat once. Since it later becomes circular, the fibers are evenly distributed in the strand as shown in FIG.

The strand exiting the crosshead die is cooled in air, but before the strand is solidified, it is pressed into a flat ribbon shape by a roll and is folded by passing it through a shaping nozzle to form a columnar shape. Become. By controlling the temperature of the roll to be equal to or lower than the melting point of the resin, it is possible to completely prevent the resin and the fibers from adhering to and engulfing the roll. The temperature of the roll is a resin having a low crystallinity, for example, polypropylene or polyethylene terephthalate, which has a melting point of 100 to 150 ° C. or less
For example, nylon and polyacetal have a melting point of 0 to 50 ° C.
The following temperatures are preferable.

The fibers are uniformly dispersed by the action of changing the cross-sectional shape of the strand from a flat ribbon shape to a folded circular shape. The dispersibility is improved by repeating the combination of the roll and the shaping die. In the present invention, the impregnation of the fiber bundle is performed by dividing it with a crosshead die and a roll, so that the operating temperature can be lowered as compared with the case where only the crosshead die is used, which causes deterioration of the matrix Can be prevented and mechanical properties can be improved. Further, by dividing the impregnation step, the roving take-up speed can be remarkably improved, and the productivity can be remarkably increased.

The method for producing the fiber-reinforced composite material of the present invention comprises:
Characteristic of the above-mentioned production method itself, there is no particular restriction on the fiber, thermoplastic resin, etc., and any high melting point (high softening point) fiber such as glass fiber, carbon fiber, aromatic polyamide fiber can be used, and its form Any continuous fiber such as roving, yarn or monofilament can be used. or,
As the thermoplastic resin impregnating the fibers, polyethylene,
Polypropylene such as polypropylene, polyethylene terephthalate and polybutylene terephthalate, nylon 6,
Nylon 66, Nylon 11, Nylon 12, Nylon 610, Nylon 612 Tower polyamide, polycarbonate, polyurethane, polyphenylene sulfide, polyphenylene oxide, polysulfone, polyetherketone, polyetheramide, polyetherimide, or other known thermoplastic resin or Any of those copolymers and modified products can be used. The strand obtained by the above-mentioned production method is used as it is or cut into an arbitrary length and used as a pellet.

[0012]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1, Comparative Example 1 A glass-reinforced polypropylene having a glass content of 40% by weight was produced using the crosshead die, roll and shaping nozzle shown in FIG. That is, polypropylene homopolymer containing 10% by weight of modified polypropylene was used as the thermoplastic resin, glass fiber was used as the fiber, and roving 1 was supplied to the crosshead die shown by 2 in FIG.
Strand 3 exiting the crosshead die, press roll 4
After being pressed with, shaping was performed with the shaping nozzle 5. The operating conditions are as follows. On the other hand, for comparison, a glass-reinforced polypropylene having a glass content of 40% by weight similar to that in Example 1 was manufactured using only the crosshead die. These products were evaluated as follows. Tensile strength: Measured according to ASTM D-638. Impact strength: Notched Izod impact strength was measured according to ASTM D-256 (test piece thickness: 6.3 mm). Content of unimpregnated glass in the product; product pellets were washed with a 1% alcohol aqueous solution, the washing solution was filtered, and the weight (ppm) of the glass collected with a filter paper was measured.

Productivity: The discharge amount was measured when the roving take-up speed was maximized in a state in which no fluff was generated and strands were not broken.

The results are shown in Table 1.

Example 2, Comparative Example 2 A glass-reinforced polypropylene was produced in the same manner as in Example 1 and Comparative Example 1 except that the glass content was 50% by weight and the pellet length was 1/2 inch. evaluated. The results are shown in Table 2.
Shown in.

[0017]

[Table 1]

[0018]

[Table 2]

[Brief description of drawings]

FIG. 1 is a schematic view showing an apparatus used in a manufacturing method of the present invention.

FIG. 2 is a schematic diagram showing a state in which the shape of a strand changes according to the present invention.

[Explanation of Codes] 1 ... Roving 2 ... Crosshead die 3 ... Strand 4 ... Pressing roll 5 ... Shaping nozzle

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Claims (2)

[Claims] 1. A continuous reinforcing fiber roving is introduced into a molten thermoplastic resin so that the molten resin is impregnated with fibers, and an excessive amount of the resin is continuously squeezed by a nozzle using a drawing device. A method for producing a strand-shaped fiber-reinforced composite material, comprising a step of pulling out, a step of pressing the strand obtained by this step into a ribbon shape with a roll, and a step of adjusting the shape by passing the pressed strand through a shaping nozzle. 2. The method for producing a strand-shaped fiber-reinforced composite material according to claim 1, wherein in the step of pressing the strand with a roll, pressing with the roll is performed within a range satisfying the following formula. b / a = 2-10 (where a is the strand diameter (c
m) and b are lateral widths (cm) of the pressed ribbon-shaped strands. )