JP3306959B2 - Method for producing long fiber reinforced synthetic resin strand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently producing a strand-like synthetic resin material reinforced with long fibers. The strand-like material can be used as it is, or can be used after being cut to an arbitrary length according to the purpose of use. An example of the latter is a pellet-shaped material used as a raw material for injection molding, injection compression molding, compression molding, and the like. In this case, cutting to a length of several mm to several tens of mm can be used. General. In the present specification, the former is classified as a long fiber reinforced synthetic resin strand (hereinafter sometimes simply referred to as a long fiber strand), and the latter is classified as a long fiber reinforced synthetic resin pellet (hereinafter sometimes simply referred to as a long fiber pellet).

[0002]

2. Description of the Related Art When it is desired to produce a molded article having a desired shape by, for example, injection molding a fiber-reinforced resin material, a pellet-like raw material in which a reinforcing resin is contained in a synthetic resin is used.
The reinforcing fibers contained in such a pellet-shaped raw material are generally short fibers, but in recent years, those obtained by impregnating a synthetic resin with long fibers aligned in one direction, that is, the long fiber pellets have been developed and have a high strength. It is evaluated as a raw material for manufacturing injection molded products.

[0003] As a method for producing these, a reinforcing fiber (hereinafter sometimes referred to as roving) is bundled and introduced, and a resin of a screw type or plunger type extruder is provided on a side surface of an impregnating head which is run in an opened state. A liquid discharge port is provided, and impregnation is performed by passing the roving through a molten synthetic resin bath formed by being pressed into the impregnation head. Then, the resin impregnated roving is taken out from the outlet nozzle of the impregnation head, and while the resin material is being hardened, it is wound up to obtain the long fiber strand, which is cut into an arbitrary length as described above, and the long fiber pellet is cut. You can also.

[0004] The reinforcing fibers are not particularly limited in terms of material, diameter, number of bundles and the like, and for example, glass fibers, carbon fibers, organic fibers, metal fibers and the like can be freely selected. Further, the synthetic resin material is not limited, and any of a thermoplastic resin and a thermosetting resin can be used.

[0005]

In the above-mentioned method, the long fibers are taken out while impregnating the long fibers in a viscous molten resin bath. Reducing resistance is an important issue. In order to reduce the take-off resistance, the first thought is to lower the viscosity of the molten resin bath. However, if the synthetic resin is heated to an excessively high temperature, there is a problem that thermal decomposition easily occurs, and the molten resin bath has a problem. There is a major limitation on increasing the heating temperature. On the other hand, if the take-up speed is too high ignoring the large resistance, there is a danger that a large tensile force will act on the long fibers and a cutting accident may occur. One or a few of them may be cut off, resulting in a problem of fluffing as described later, which may necessitate interruption of production.

For example, in the actual production process, after the start of production, the take-off resistance of the long fiber increases shortly, and in some cases, the take-off becomes impossible in a few hours and the production is interrupted. In such a case, when the impregnating head is disassembled and inspected, the outlet nozzle and the upstream side thereof are filled with fiber aggregates (for example, black aggregates using carbon fibers) in the impregnation head. The nodules are placed in the impregnation head.
It is formed by winding an impregnating roller. Therefore, in order to reuse the impregnating head, it is necessary to completely disassemble and clean the impregnating head. Even if two or more sets of impregnating heads are prepared and used alternately, the decrease in productivity is extremely large. It had to be something.

[0007] The inventors of the present invention used an impregnating head made of a transparent material and studied it from various angles in order to investigate and study the cause of an increase in the take-up resistance of the long fiber during continuous production, and eventually the drawback. . As a result, if the take-up speed is too high,
It was found that fluffing occurred from the running long fiber bundle, and the fluff was drawn immediately before the outlet nozzle and became entangled with the fluff, which grew one after another in a short time to form the above-mentioned lump.

The present invention has been made to solve such inconvenience. Even when it is desired to increase the long fiber take-up speed to a desired speed and to improve the productivity, the long fiber is drawn. An object of the present invention is to establish a method in which the picking can be performed continuously without any inconvenience over a long period of time.

[0009]

According to the method of the present invention which can achieve the above object, the synthetic resin bath container is formed in a cylindrical shape, and the cylindrical container is formed so that the outlet nozzle is located downward. While arranging it in an inclined manner and running the long fiber obliquely downward and obliquely downward, while injecting the molten synthetic resin from near the outlet nozzle and overflowing the molten synthetic resin from near the upper end of the cylindrical container, It is intended to impregnate the resin.

By adopting this configuration, the resistance of the molten resin bath is considerably reduced, and the critical take-off speed at which the long fibers do not fluff is increased, which can contribute to the improvement of productivity. However, even in such a case,
If the take-up speed is further increased, fluffing may occur from the long fiber bundle due to friction or ironing during the process of passing through the opening / impregnating roller or being taken out from the outlet nozzle of the impregnating head. For some reasons, continuous pick-up over a long period of time may not be possible. Therefore, as a result of further study, if the resin-impregnated long fiber is taken up in a twisted state, the fluffing is taken in the twist and pulled out of the outlet nozzle, and the above-mentioned situation in which the take-out cannot be taken out. I knew I didn't fall.

[0011]

The significance of using a synthetic resin bath container (impregnation head) in a cylindrical shape and an inclined arrangement such that the outlet nozzle is on the lower side will be described. Before adopting such an inclined arrangement, horizontal arrangement and vertical arrangement were generally performed. Among these, in the horizontal arrangement, the pressure inlet of the molten resin and the inlet of the roving are provided at opposing positions, and it is generally recognized that the resin impregnation is performed by flowing the molten resin in the direction of taking the roving and in the countercurrent direction. there were. However, in the case where the impregnation head is arranged horizontally, the pressure inlet and the overflow of the molten resin are substantially at the same height.Therefore, in order to fill the inside of the impregnation head with the molten resin, the injection amount of the molten resin is increased. This has the consequence that the amount of resin spilled out of the overflow increases and inevitably the flow of molten resin in the impregnation head is considerably faster. Therefore, the roving during the take-off travel receives a large resistance due to the high-viscosity molten resin flowing from the opposite side, so that a state in which a trouble such as cutting or flapping easily occurs as described above. In the horizontal arrangement method, the impregnating head is oriented sideways, so that the hydrostatic pressure in the head must be low, and the pressure impregnation effect due to the weight of the molten resin cannot be expected. there were.

On the other hand, in the vertical arrangement, the pressure inlet of the molten resin becomes the lower end of the impregnation head, and the roving is taken from top to bottom. Therefore, the molten resin that has been pushed into the impregnating head from below and filled to the required liquid level maintains a stationary state, and only the roving runs in the molten resin. Does not cause cutting or fluffing due to resistance. In addition, since the liquid level can be sufficiently high, the hydrostatic pressure is ensured, and the advantages that the impregnation property is improved are also exhibited. However, the reduced flow of the molten resin means that
Means that stagnation of molten resin occurs in the impregnation head, which increases the dwell time of holding at high heat and increases the risk of causing thermal degradation of the resin. The disadvantage is that the operation must be interrupted. Also, in the vertical arrangement, the long fiber strand is drawn vertically downward from the outlet nozzle, so that the take-off mechanism member needs to be mounted further downward. This causes inconvenience in device maintenance. Therefore, it is conceivable that the long fiber strand is largely bent immediately after the impregnating head comes out and is taken in the horizontal direction, but there is a disadvantage that unnecessary force must be applied to the long fiber strand.

On the other hand, in the inclined arrangement of the present invention, the flow resistance of the molten resin is smaller than in the case of the horizontal arrangement, the effect of using the hydrostatic pressure is better than in the case of the horizontal arrangement, and the risk of thermal degradation is lower in the case of the vertical arrangement. Excellent effects such as further improvement can be obtained. In particular, by causing a part of the press-fit resin to overflow from the upper end of the inclined arrangement, the old resin is pushed up and discharged by the new resin.
The risk of thermal degradation is almost eliminated.

According to a preferred embodiment of the present invention, the angle of inclination of the impregnation head is preferably about 3 to 45 ° with respect to a horizontal line, and the molten resin is press-fitted from the lower side of the slope to a position higher than the press-in port. An overflow is formed at a certain upper end. The roving is introduced from the upper end and is drawn out from the outlet nozzle at the lower end.

Although the above structure has reduced the obstacle to increasing the take-up speed, if the take-up speed is further increased to improve productivity, flapping occurs again as described. Therefore, in order to prevent this, it is recommended to carry out the above-mentioned twisting while giving. That is, a twisting mechanism (for example, a rotation mechanism) is provided on the roving take-off member provided on the downstream side of the impregnation head, and the resin impregnated filament is twisted and taken off. When such a twist is applied, the twist is transmitted into the impregnating head through the outlet nozzle hole, and the fluff that has begun to become entangled immediately before the outlet nozzle is taken out of the outlet nozzle by taking it into the twist. Is exhibited. As a result, the formation of the lumps immediately before the outlet nozzle is prevented, and even if continuous operation is performed for a long time, troubles in taking in the resin-impregnated long fibers do not occur and excellent productivity can be exhibited. When such a twist is applied, a force for expelling bubbles in the interstices of the fibers and forcibly moving the molten resin between the fibers acts, so that the effect of enhancing the impregnation property of the resin is also obtained.

[0016]

1 is a side view explanatory view conceptually showing an apparatus for carrying out the present invention, and FIG. 2 is a plan view explanatory view. In these figures, reference numeral 1 denotes an impregnating head (synthetic resin bath vessel) which is arranged obliquely, 2 denotes a molten synthetic resin pressure inlet, and a roving 3a sent from an arrow A enters the impregnating head 1 from an inlet nozzle 4. After sequentially passing through the grooved opening / impregnating roller 6a and the normal opening / impregnating roller 6b having no groove, it is drawn through the guide roller 7 and the converging roller 8 toward the outlet nozzle 5. On the other hand, since the molten synthetic resin press-fitted in the direction of arrow M from the molten synthetic resin pressure inlet 2 is filled in the impregnating head 1, the roving 3a is impregnated with the resin while passing through the rollers, and the outlet nozzle 5 is taken in the direction of arrow B as a resin-impregnated roving 3b. The supply amount of the roving 3a and the injection amount of the molten synthetic resin are controlled so as to maintain a balance, but in the present invention, the latter is slightly excessively overblowed in the direction of arrow N in FIG.

The resin impregnated roving 3b drawn in the direction of arrow B as described above is rotated by a twist generator (not shown) as shown by arrow C, and the twist formed by the rotation proceeds in the direction opposite to arrow B to converge. The roller 8 is reached. Accordingly, twists are generated and grown in the resin-impregnated roving 3b starting from the downstream side of the converging roller 8. Therefore impregnation head 1
Exit nozzle 5 as the roving 3a travels
The fluff drawn in the direction or the fluff generated by rubbing with the outlet nozzle 5 is entrained into the twist in the above-mentioned generation / growth process and is accompanied by the resin impregnated roving 3b drawn from the outlet nozzle 5. Then, it is drawn out of the outlet nozzle 5 to produce a long fiber strand. Therefore, no fluff is left in the impregnation head 1 and no lump of fibers is generated.

[0018]

The present invention is configured as described above, so that even if the resin-impregnated long fibers are taken at a high speed, cutting and fluffing of the long fibers can be reduced, and thermal decomposition of the molten resin can be achieved. Does not occur. Therefore, the entanglement of the fibers does not grow in the impregnation head. Therefore, excellent productivity can be maintained for a long time without increasing the take-up resistance due to the fiber lumps or preventing the fibers from being taken out.

[Brief description of the drawings]

FIG. 1 is a side view explanatory view of an apparatus for carrying out the present invention.

FIG. 2 is an explanatory plan view of an apparatus for carrying out the present invention.

[Explanation of symbols]

 Reference Signs List 1 impregnation head (synthetic resin bath container) 2 molten synthetic resin pressure inlet 3a roving 3b resin impregnated roving 4 inlet nozzle 5 outlet nozzle 6a grooved opening / impregnation roller 6b opening / impregnation roller 7 guide roller 8 converging roller

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroki Koga 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Research Institute (56) References JP-A-4-35910 ( JP, A) JP-A-1-263005 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29B 11/16 B29B 15/08-15/14

Claims (2)

(57) [Claims] 1. A method in which long fibers are uniformly introduced into a synthetic resin bath container, and while the long fibers are impregnated with the synthetic resin, the resin-impregnated long fibers are taken out from an outlet nozzle of the synthetic resin bath container. In the method for producing a long fiber reinforced synthetic resin strand, the synthetic resin bath container is formed in a cylindrical shape, and the cylindrical container is arranged so as to be inclined such that the outlet nozzle is downward,
While running the long fiber from obliquely upward to obliquely downward, injecting molten synthetic resin from near the outlet nozzle and performing resin impregnation while overflowing the molten synthetic resin from near the upper end of the cylindrical container. A method for producing a long fiber reinforced synthetic resin strand, characterized in that: 2. The method for producing a long fiber reinforced synthetic resin strand according to claim 1, wherein the long fiber drawn from the synthetic resin bath container is drawn in a twisted state.