JP2015006749A - Production method of fiber-reinforced resin intermediate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced resin intermediate: where a kneaded object discharged from an extruder or an injection machine can be serviced in next molding processing; which is kept in a high temperature state to a degree of enabling processing; and where handling is easily.SOLUTION: In a production method of a fiber-reinforced resin intermediate,: a molten thermoplastic resin and a reinforcing fiber are kneaded by an extruder or an injection machine under pressure p; and then the fiber-reinforced resin intermediate is produced by pressing and cooling a kneaded object released from the extruder or the injection machine to under atmospheric pressure or under reduced pressure so as to be a prescribed thickness t. The volume of the kneaded object becomes 1.5 times or more a volume under the pressure p by being released to under atmospheric pressure or under the reduced pressure. In the fiber-reinforced resin intermediate, the thermoplastic resin at a surface part is solidified and an inner thermoplastic resin is kept in a molten state.

Description

  The present invention relates to a method for producing a fiber reinforced resin intermediate used for molding a kneaded product of a reinforced fiber and a thermoplastic resin discharged by an extruder or an injection machine, and maintains a state suitable for molding and handling. The present invention relates to a method for producing a finished fiber reinforced resin intermediate.

  Since the fiber reinforced resin is lightweight and excellent in mechanical strength, its application range is expanding. In particular, in aircraft and automobiles, the scope of application of fiber reinforced resin to aircraft or automobile parts is expanding for the purpose of weight reduction.

  Application of fiber reinforced resin to automobile parts requires efficient production such as economy and mass productivity. For example, in Patent Document 1, a chopped strand state reinforcing fiber, a granular solid and a thermoplastic resin are extruded by an extruder to form a pellet, and the pellet is injected into an injection molding machine to perform injection molding. The raw material of roving of reinforcing fiber, granular solid and thermoplastic resin are put into the extruder, and the kneaded material in which the reinforcing fiber is cut and defibrated and uniformly dispersed in the molten thermoplastic resin is extruded and directly connected to the extruder. There has been proposed a method of injection molding by using an injection machine.

  Patent Document 2 discloses a compression molding method in which a molten material is supplied from a material supply device to a lower mold that has been opened, and then the lower mold and the upper mold are closed to compress the molten material. A lower mold that includes a pressure position and is movable in one direction and the other direction; and a material supply device that is movable in a direction intersecting with the movement direction of the lower mold. The molten material is supplied by performing the movement and the movement of the material supply device in the direction intersecting with the movement direction of the lower die simultaneously or alternately, and the lower die is fixed to the pressing position of the press device. A compression molding method for lowering the upper mold and compressing the molten material has been proposed. According to this method, the molten material can be supplied to a desired position of the lower mold without complicating the structure of the material supply apparatus.

  In Patent Document 3, a reinforced fiber and a thermoplastic resin having a predetermined length are extruded by a single screw extruder, firstly deposited on a first half mold (lower mold) of a matched mold, and then the lower mold is matched. There has been proposed a method in which a lower half and an upper mold are used for compression molding after being transferred to the lower surface of a compressor having a second half mold (upper mold) of the mold. According to this method, it is said that a molded body having a low tensile strength and bending strength anisotropy can be produced at an extremely low pressure.

JP 2009-242616 Japanese Patent No. 5093825 Special Table 2007-530326

  The kneaded material in which the reinforcing fibers are dispersed in the molten thermoplastic resin can be formed by an extruder or an injection machine. And a molded object can be manufactured by injection-molding this kneaded material with an injection machine, or compression-molding with a compressor. Since the processing method described in Patent Document 1 or 2 uses a processing apparatus in which an extruder and an injection machine are integrated, a molded body can be manufactured with high production efficiency. However, since the extruder and the injection machine are integrated, there is a problem that the entire processing equipment is enlarged, and there is a problem that it is not preferable as a method of processing various shaped bodies in terms of shape or material.

  On the other hand, the processing method described in Patent Document 3 has a form in which the extruder and the compressor are separated, but actually the kneaded material deposited on the lower mold is transferred to the compressor provided with the upper mold. The upper mold is pressed and compression molded, and is similar to the method described in Patent Document 2. The processing method described in Patent Document 3 requires a larger-scale facility and has a problem that the production efficiency is inferior to the processing method described in Patent Document 2.

  Further, in the method described in Patent Document 3, the kneaded material deposited on the lower mold is said to have a melted near net shape of a desired final molded body, but is discharged from an extruder. Immediately after the kneaded product, the reinforcing fibers are oriented three-dimensionally, there is a tendency to expand to several times or more due to the springback and become a bulky irregular shape. Therefore, in practice, it is not always easy to handle (handle) the kneaded material and place the kneaded material in a predetermined size at a predetermined position of the mold. In order to place the kneaded material at a predetermined position of the mold, the edge of the kneaded material must be cut, which causes a problem that the cutting blade is easily worn.

  In view of such a conventional problem, the present invention allows the kneaded material discharged from the extruder or the injection machine to be subjected to the next molding process, and is maintained at a high temperature state capable of being processed and handled. It aims at providing the fiber reinforced resin intermediate body which is easy. Moreover, it aims at providing the manufacturing method of the molded object using this fiber reinforced resin intermediate body.

  The method for producing a fiber reinforced resin intermediate according to the present invention comprises kneading a thermoplastic resin and a reinforced fiber melted by an extruder or an injection machine under pressure p, and then from the extruder or the injection machine under atmospheric pressure or reduced pressure. A method for producing a fiber reinforced resin intermediate by pressing and cooling the kneaded material released to a predetermined thickness t, wherein the kneaded material is released under atmospheric pressure or reduced pressure and has a volume of p under pressure. The fiber reinforced resin intermediate is 1.5 times or more, and the thermoplastic resin on the surface thereof is solidified and the internal thermoplastic resin is held in a molten state.

  In the said invention, the unevenness | corrugation of the surface part of a fiber reinforced resin intermediate body shall be 1/2 or less of predetermined thickness t.

  The kneaded product is pressed and cooled in a state where the thermoplastic resin inside the fiber reinforced resin intermediate is kept in a molten state and the thickness of the fiber reinforced resin intermediate is maintained in the range of t ± 20%. It is good to carry out to the extent that it can receive the next shaping | molding process.

  The reinforcing fiber can be made of carbon fiber and have a fiber length of 1 to 100 mm.

  By compression-molding the fiber-reinforced resin intermediate, a fiber-reinforced resin molded body such as an automobile part can be produced with high productivity.

  ADVANTAGE OF THE INVENTION According to this invention, the fiber reinforced resin intermediate body which can be used for the following shaping | molding process can be provided irrespective of the production cycle of the kneaded material by an extruder or an injection machine. By compressing and molding this fiber reinforced resin intermediate, the fiber reinforced resin molded product can be produced with high production efficiency.

It is a schematic diagram explaining the manufacturing method of the fiber reinforced resin intermediate which concerns on this invention. It is a schematic diagram explaining handling of a fiber reinforced resin intermediate.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic view for explaining a method for producing a fiber-reinforced resin intermediate according to the present invention. This fiber reinforced resin intermediate is produced by kneading a thermoplastic resin melted with an extruder or an injection machine and a reinforcing fiber under pressure p, and then releasing from the extruder or injection machine under atmospheric pressure or reduced pressure. The kneaded product is pressed and cooled to a predetermined thickness t to produce a fiber reinforced resin intermediate. That is, as shown in FIG. 1, kneading discharged from an extruder 1 (or an injection machine) and having a volume of 1.5 times or more of the volume under pressure of the extruder 1 under the discharged atmospheric pressure or reduced pressure. The product 5 is pressed by the cooling roll 3 held at a predetermined interval (predetermined thickness t), the thermoplastic resin on the surface of the kneaded product 5 is solidified, and the internal thermoplastic resin is held in a molten state. This is a method for producing a product (fiber reinforced resin intermediate 51).

  As the extruder 1, a known extruder can be used. In the extruder 1, the thermoplastic resin and the reinforcing fiber are kneaded under pressure of 0.01 MPa to 30 MPa. The reinforcing fibers are glass fibers, carbon fibers, and the like, and are not particularly limited. However, the method for producing the present fiber reinforced resin intermediate can be suitably used when the reinforcing fibers are carbon fibers. When the reinforcing fiber is a carbon fiber, it can be suitably used for the production of a fiber reinforced resin intermediate having a fiber length of 1 to 100 mm, particularly 3 to 60 mm. This is because such a kneaded product containing carbon fibers is suitably used for molding a fiber reinforced resin molded article such as an automobile part, and has a large expansion coefficient due to the spring back of the carbon fibers.

  The p-kneaded product under pressure expands to several times the volume when discharged from the extruder 1 under atmospheric pressure or reduced pressure. For example, a kneaded product 5 obtained by extruding a kneaded product of carbon fiber and a thermoplastic resin (polyamide) having a weight average length of 25 mm and a volume content of 20% from an extruder having a die discharge port height of 12 mm is under atmospheric pressure. It was 36mm, and the unevenness was about 20mm. In the method for producing the present fiber reinforced resin intermediate, such a kneaded product 5 is pressed and cooled. For pressing and cooling, a rotating cooling roll can be used as shown in FIG. However, the present invention is not limited to this, and if the kneaded product is of a certain length as in an injection machine, the kneaded product may be sandwiched between flat plates and pressed and cooled.

  The kneaded product 5 is pressed and cooled. For example, it is pressed and cooled to a predetermined thickness t (30 mm). In the fiber reinforced resin intermediate 51 molded in this way, the thermoplastic resin on the surface portion was solidified, and the internal thermoplastic resin was held in a molten state. The irregularities on the surface of the fiber reinforced resin intermediate 51 were within 15 mm. The kneaded product 5 is preferably pressed and cooled so that the unevenness of the surface portion of the fiber reinforced resin intermediate 51 is ½ or less of the predetermined thickness t. This facilitates the handling of the fiber reinforced resin intermediate 51 and can be easily placed at a predetermined position of the mold.

  Further, it is preferable to press and cool the kneaded product 5 so that the thickness of the fiber reinforced resin intermediate 51 is maintained in the range of t ± 20% until the next molding process is performed. The fiber reinforced resin intermediate 51 in such a state is suppressed in the spring back of the reinforced fiber due to the solidification of the thermoplastic resin on the surface portion, and the thermoplastic resin inside is in a molten state and the next molding process This is because is in a state where it is possible. The fiber reinforced resin intermediate 51 may be anything that can be handled without being deformed or divided by its own weight. The thickness and temperature of the solidified layer on the surface portion of the fiber reinforced resin intermediate 51 or the thickness and temperature of the inner molten layer are optimally suited depending on the shape and material of the fiber reinforced resin intermediate 51. Conditions are selected.

  The fiber reinforced resin intermediate 51 can be handled by the operation arm 4 as shown in FIG. Further, the fiber reinforced resin intermediate 51 can be handled easily and quickly, and can be easily placed on a predetermined portion of the mold, and the fiber reinforced resin intermediate 51 can be compression-molded with high productivity. it can. In the compression molding of the fiber reinforced resin intermediate 51, its production method and the like are not particularly limited. However, when the fiber reinforced resin intermediate 51 is compression molded, the surface portion of the intermediate solidified immediately before the compression molding is used as an infrared heater. It can be reheated using such as. In reheating, it is preferable to soften the fiber-reinforced resin intermediate 51 so that it can flow without being cracked when pressurized. Even if such reheating is performed, the surface of the fiber reinforced resin intermediate 51 has already been pressurized and is made uniform in material. Has the effect of being relatively smooth and less prone to irregular irregularities.

  The fiber reinforced resin intermediate according to the present invention has been described above. When the present fiber reinforced resin intermediate is molded by an extruder, the continuously extruded kneaded product can be cut by water pressure, laser, or the like, in addition to shearing with a blade or the like. In the case of molding a fiber reinforced resin intermediate containing carbon fibers, for example, it is preferable to cut the extruded kneaded material by using a difference in height or a difference in moving speed of the conveyor. The kneaded product has a low bulk density and is not easy to cut with a blade, and the blade is heavily worn, which is not preferable.

1 Extruder
11 Die outlet
3 Cooling roll
4 Operation arm
5 Kneaded material
51 Fiber reinforced resin intermediate

Claims (5)

After kneading the thermoplastic resin and reinforcing fiber melted by an extruder or injection machine under pressure, press and cool the kneaded material released from the extruder or injection machine under atmospheric pressure or reduced pressure to a predetermined thickness t. A method for producing a fiber reinforced resin intermediate,
The kneaded product is opened under atmospheric pressure or reduced pressure and becomes 1.5 times or more the volume of p under pressure,
The fiber reinforced resin intermediate is a method for producing a fiber reinforced resin intermediate in which a thermoplastic resin on a surface portion thereof is solidified and an internal thermoplastic resin is maintained in a molten state.   The method for producing a fiber reinforced resin intermediate according to claim 1, wherein the unevenness of the surface portion of the fiber reinforced resin intermediate is 1/2 or less of a predetermined thickness t.   Pressing and cooling of the kneaded product is carried out in the state where the thermoplastic resin inside the fiber reinforced resin intermediate is kept in a molten state and the thickness of the fiber reinforced resin intermediate is maintained in the range of t ± 20%. The method for producing a fiber-reinforced resin intermediate according to claim 1 or 2, wherein the method is performed to such an extent that it can be molded.   The method for producing a fiber-reinforced resin intermediate according to any one of claims 1 to 3, wherein the reinforcing fiber is made of carbon fiber and has a fiber length of 1 to 100 mm.   A method for producing a fiber-reinforced resin molded article by compression molding using the fiber-reinforced resin intermediate according to any one of claims 1 to 4.

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