JP3114311B2 - Method for producing fiber reinforced resin strand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for producing a fiber-reinforced resin strand using a continuous long reinforcing fiber bundle,
More specifically, the present invention relates to a method for efficiently producing a fiber-reinforced resin strand exhibiting high flexibility and buckling resistance.

[0002]

2. Description of the Related Art FRTP (Fiber Reinforced Thermo Pl)
As a method of producing a prepreg of astic; fiber-reinforced thermoplastic, a continuous long reinforcing fiber bundle is passed through a molten thermoplastic resin bath, and the fiber bundle is impregnated with a resin and a cross section is formed. The most widely used method is to continuously produce fiber-reinforced resin strands (hereinafter simply referred to as "strands") by shaping and shaping the shape with a shaping die. FIG. 4 is an explanatory view showing an example of the strand manufacturing apparatus, and FIG. 5 is an enlarged cross-sectional view of a main part of the strand manufacturing apparatus.
After being supplied to the crosshead 22 and passing through the resin passage 22a of the crosshead 22, it is discharged after being compounded with a large number of reinforcing fibers 1 and 1 (see FIG. 5).
Thereafter, the cross-section is formed into a desired shape by the shaping die 23 and fed to the cooler 24 as the strand 3. The strand 3 which has been solidified by cooling is pulled out in the direction of the arrow by a puller 25 and cut to a predetermined length by a cutter 26 as necessary. A take-up reel or the like may be provided in place of the cutter 26.

On the other hand, FIG. 6 is an explanatory view showing another example of a production apparatus for the strand 3. The molten resin material 2 is continuously supplied from the right side of the figure into the crosshead 5 by an extrusion screw 7, and the reinforcing The fibers 1, 1... Are supplied so as to penetrate from top to bottom along the axial longitudinal direction of the crosshead 5, and in this passing process, a reinforcing fiber bundle is impregnated with a resin material and a desired cross section is formed in the shaping die 9. And immediately cooled and hardened by the cooler 10. The strand 3 is taken up on a take-up reel 17. The spreaders 8, 8,... Provided in the crosshead 5 are used for running the reinforcing fiber bundle in a zigzag manner to defibrate and improve impregnation.

[0004]

In the strand 3 manufactured as described above, the reinforcing fibers are oriented parallel to the longitudinal direction of the strand, and the tensile strength and the compressive force in the longitudinal direction of the strand are reduced. Exhibits excellent mechanical properties. However, regarding the bending of the strand, the reinforcing fiber itself has elasticity, but the entire strand is poor in flexibility, and there is a serious problem that the strand is easily broken or buckled when the strand is bent or curved.

On the other hand, in order to ensure the adhesion between the reinforcing fibers and the resin material, there is a method of impregnating the resin with a low molecular weight using a resin having a low melt viscosity (Japanese Patent Publication No. 63-37694).
No.), this method has a disadvantage that the heat resistance and fatigue strength of the strand become insufficient. Further, as shown in FIG. 6, there is considered a means in which the reinforcing fiber bundle is pressed against the spreader 8 to be defibrated so that the resin easily enters between the fibers. However, there is a problem that the mechanical properties of the steel are deteriorated. Therefore, the present inventors provide a fiber reinforced resin strand that gives a good twist to the reinforcing fiber and performs sufficient resin concentricity, and as a result, improves both flexibility and buckling resistance. The research was repeated for the purpose of completing the present invention.

The fiber reinforced resin strand which has achieved the above object is provided by being manufactured by the following method. That is, in the first method, a long reinforcing fiber bundle is immersed in a molten resin bath of a thermoplastic resin to impregnate the fiber bundle with the molten resin, and further drawn out of the molten resin bath through a die. The gist is that the molten resin-impregnated reinforcing fiber bundle is rotated in a twisting direction by a roller that rotates in an inclined direction with respect to the drawing direction, and the molten resin is impregnated between the fibers while twisting the reinforcing fiber bundle. Things. In the second method, a long reinforcing fiber bundle is immersed in a molten resin bath of a thermoplastic resin to impregnate the fiber bundle with the molten resin, and then drawn out of the molten resin bath through a die. The gist of the invention is to impregnate the reinforcing fiber bundle with the molten resin while twisting the reinforcing fiber bundle by winding it around a revolving reel that revolves around the drawing direction axis. With these methods, good resin impregnation properties are exhibited, and also good flexibility is given to the strand. Further, in the present invention, the reinforcing fiber bundle is preferably immersed in the molten resin bath while being defibrated.

[0007]

In the strand produced by the above method of the present invention, since the reinforcing fiber bundle is twisted, when a bending force is applied, each of the constituent fibers 1 is converted into the strand shown in FIG.
As shown in the figure, it is displaced to the inside and outside of the bend alternately to bend, so that the tensile stress and the compressive stress are equalized, the resistance to bending is reduced, and the buckling or fracture of the strand is prevented. While preventing, the strand itself exhibits high flexibility.

Further, in the manufacturing method of the present invention, the twist given after the resin impregnation is also transmitted to the strand running in the resin bath, and as a result, the resin impregnation is performed while the reinforcing fiber bundle is being twisted. In addition, the contact point between the resin and the reinforcing fiber changes three-dimensionally due to the twist, so that the resin impregnation can be reliably performed, and the resin and the fiber can be surely brought into close contact with each other.

In the above method, even if the reinforcing fibers are broken during the impregnation with the resin, the fibers are wound into the fiber bundle by the twisting action, so that the broken fibers are caught on the crosshead or the shaping die. It does not increase the pull-out resistance, and the broken fibers are less likely to stay inside the crosshead or shaping die, so these cleaning operations can be reduced and efficient production can be continued. Be able to do it.

[0010]

FIG. 1 is an explanatory view showing an example of an apparatus for producing the strand of the present invention. A molten resin material 2 is continuously supplied from an extruder 6 into a crosshead 5. On the exit side of the crosshead 5, a shaping die 9, a cooler 10, a twist roller 11
a, 11b and a pull-out roller 12 are arranged in this order, and a spreader 8 for defibrating the reinforcing fiber bundle is provided in the crosshead 5. Are immersed in the molten resin material 2 in the crosshead 5 and impregnated with the resin, the cross-sectional shape is determined by the shaping die 9, and cooled and hardened in the cooler 10. Twist roller 1
The rollers 1a and 11b are configured to be driven in reverse rotation by rubber rollers, and the rollers 11a and 11b are disposed to be inclined in the reverse direction in a horizontal plane, and the strand 3 is held at the intersection of the rollers 11a and 11b. Then, the strand 3 is rotated about the axis by pulling in the direction of the arrow.
Thereby, twist is provided between the cooler 10 and the spreader 8a on the most downstream side. In order to equalize the outer surface shape of the strand 3 as much as possible, it is preferable to arrange the outlet of the crosshead 5, the shaping die 9 and the cooler 10 as close as possible.

FIG. 2 is an explanatory view showing another embodiment of the twisting machine used in the present invention. The strand 3 is wound on a take-up reel 17 rotating on its own axis, and the take-up reel 17 is Guide roll 1
The strand 3 is rotated around the axis downstream of 6a, so that the reinforcing fiber bundle is twisted. The code guide rolls 16a and 16b assist the movement of the strand 3 in the longitudinal direction.

The resin material used in the present invention is not particularly limited, and any thermoplastic resin such as a high melting point heat resistant resin (such as polyetheretherketone or polyethersulfone) can be used. There is no limitation, and any inorganic fiber or organic fiber can be used.

(Example 1) An ethylene-acrylic acid copolymer (EAA) was used as a thermoplastic resin by using the apparatus shown in FIG.
E glass roving (Nippon Glass Fiber 2
400 tex), and a fiber reinforced resin strand (cross-sectional diameter 2.1 mmφ) having a fiber content of 74 wt% was produced.
The glass roving is passed through a molten resin bath, and a plurality of spreaders arranged in the crosshead 5 are alternately bridged over 5 m.
/ Min. Further, it was shaped into a rod by passing through a shaping die.

The strand thus produced was rich in flexibility and did not buckle even when bent to a radius of curvature of 50 mm. Measurement of the squat flexion radius was 50, 150, and 20 respectively.
By bending the strand along an arc-shaped jig having a radius of 0 or 250 mm and bending it into a hoop shape, it was visually observed at which radius buckling would occur. The tensile strength and tensile modulus are AS
It was measured according to TM D 3916, but no decrease in the mechanical strength of the strand was observed even if the fibers were twisted,
Rather, the tendency for improvement was observed. After the continuous operation for 5 hours, the crosshead was disassembled and the interior was examined. The fluff of the remaining fibers was negligible in operation.

Comparative Example 1 A glass fiber reinforced resin strand was produced using the same crosshead as in Example 1 except that no twisting machine was used. The material, fiber content, and manufacturing conditions are the same as in Example 1. The resulting strand has a radius of curvature of 2
Buckling occurred at 50 mm. Also, about 2 hours after the start of production, broken fibers accumulated in the shaped portion of the crosshead and clogged the die, so it was necessary to interrupt the operation and perform cleaning. Table 1 shows the mechanical properties of the strands obtained in Example 1 and Comparative Example 1.

[0016]

[Table 1]

Example 2 Using an apparatus shown in FIG. 2, an ethylene / acrylic acid copolymer (EAA) was used as a thermoplastic resin.
Resin, Dow Chemical's Primacol 5990)
E-glass roving (Nippon Glass Fiber 2
400 tex) and a fiber content of about 70 wt%
Of the fiber reinforced resin strand (cross-sectional diameter 1.6 mmφ). The glass roving was passed through a molten resin bath, and a plurality of spreaders arranged in the crosshead 5 were alternately bridged and pulled out at a speed of 5 m / min. Further, while the strand was wound by 0.3 m, the take-up reel also made one rotation in the vertical plane, whereby the fibers in the strand were twisted and then cooled to form a rod.

The strand thus produced was rich in flexibility, and did not buckle even when the radius of curvature exceeded 50 mm. The tensile strength and tensile modulus of the strand did not decrease even if the fiber was twisted, but rather tended to improve. After the continuous operation for 5 hours, the crosshead was disassembled and the inside of the die was examined. The fluff of the remaining fibers was negligible in operation.

(Comparative Example 2) A glass fiber reinforced resin strand (cross-sectional diameter: 1.6 mmφ) was produced in the same manner as in Example 2 without twisting during winding. The material, fiber content, and manufacturing conditions are the same as in Example 2. Buckling occurred in the obtained strand when the radius of curvature was 250 mm or more. Also, about 4 hours after the start of the production, fuzz accumulated in the shaping portion of the crosshead die and clogged the die, so that it was necessary to interrupt the operation and perform cleaning. Examination of the degree of fiber damage at the buckled portion by soft X-ray photography revealed that strands twisted on the contained fibers were clearly more seated than conventional strands in which the fibers were oriented one-dimensionally in the take-off direction. It was found that there was little fiber damage at the flexure.

(Embodiment 3) Using the same crosshead extruder as in Embodiment 2, using E-glass yarn (2400 tex, manufactured by Nippon Glass Fiber) previously twisted as a reinforcing fiber,
Glass fiber reinforced resin strands were manufactured. As the thermoplastic resin, as in Example 2, an ethylene / acrylic acid copolymer (EAA resin, Primacol 5 manufactured by Dow Chemical Co., Ltd.) was used.
990), and the cross-sectional diameter (1.6 mmφ) of the strand was determined so that the fiber content also became about 70 wt%. The glass yarn is passed through a molten resin bath, and a plurality of spreaders arranged in a crosshead are alternately bridged, and 5 m / min.
And cooled through a shaping die to form a rod.

This strand was rich in flexibility and did not buckle even if the radius of curvature exceeded 50 mm. However, since the fibers were twisted in advance, the resin did not completely penetrate into the inside of the fiber bundle, and the apparent fiber content became extremely high due to insufficient supply of the resin into the strands (80 wt.
%). For this reason, the adhesion between the resin and the fiber was significantly poor, and a decrease in tensile strength and tensile elasticity of 10 to 15% was observed as compared with that using glass roving. Table 2 shows the mechanical properties of the strands obtained in Examples 2 and 3 and Comparative Example 2.

[0022]

[Table 2]

[0023]

The strand produced according to the present invention has flexibility and exhibits high buckling resistance against bending.
Further, in the method of the present invention, since the strand is impregnated while being given a good twist, the reinforcing fiber and the resin material can be firmly adhered to each other. Efficient production can be performed without getting caught.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of an apparatus used in the method of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the apparatus used in the method of the present invention.

FIGS. 3A and 3B are explanatory views showing the strand of the present invention in a straight line state and in a bent state.

FIG. 4 is an explanatory diagram showing an example of an apparatus used in a conventional method.

FIG. 5 is a partially cutaway explanatory view of the crosshead shown in FIG. 4;

FIG. 6 is an explanatory diagram showing another example of an apparatus used in a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reinforcing fiber 2 Molten resin material 3 Fiber reinforced resin strand 11a, 11b Twisting roller 15 Rotary shaft 17 Take-up reel

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-78628 (JP, A) JP-A-63-12785 (JP, A) JP-A-63-264306 (JP, A) 19809 (JP, A) JP-A-2-12783 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29B 11/16 B29B 15/14

Claims (3)

(57) [Claims] 1. A long reinforcing fiber bundle is melted with a thermoplastic resin.
Dipped in a molten resin bath to impregnate the fiber bundle with the molten resin
After further drawing out of the molten resin bath through a die,
A roller that rotates in an inclined direction with respect to the drawing direction
To rotate the molten resin-impregnated reinforcing fiber bundle in the twisting direction,
Impregnation of molten resin between fibers while twisting the reinforcing fiber bundle
Made in the fiber-reinforced resin strand, wherein the advancing
Construction method . 2. A long reinforcing fiber bundle is melted with a thermoplastic resin.
Dipped in a molten resin bath to impregnate the fiber bundle with the molten resin
After further drawing out of the molten resin bath through a die,
Revolving around the axis of the drawing direction
A method for producing a fiber-reinforced resin strand, comprising: impregnating a molten resin between fibers while twisting the reinforcing fiber bundle by winding on a reel . (3) While melting the reinforcing fiber bundle,
3. The fiber strength according to claim 1, which is immersed in a resin bath.
Method for producing a plasticized resin strand.