JP2017087707A - Method for highly dispersing fiber of fiber-reinforced thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite molding material retained in a monofilament and highly dispersed state, the fibers of 1 to 4 mm in length added in a thermoplastic resin and being mixed.SOLUTION: A composite material of a thermoplastic resin including highly dispersed fibers is produced by compressing the mixture of monofilament or the fiber prepared by preliminarily fibrillating a chopped strand into a monofilament state, and a prescribed amount of the thermoplastic resin when preparing the fiber-reinforced composite thermoplastic resin by adding the fiber of 1 to 4 mm in length to the thermoplastic resin, and by pelletizing the compressed massive material using a biaxial extruder.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a thermoplastic resin pellet reinforced with fibers such as glass, carbon fiber, and cellulose nanofiber.

  As a method of kneading fibers such as glass, carbon fiber, and cellulose nanofiber into a thermoplastic resin to produce fiber-reinforced thermoplastic resin pellets, the thermoplastic resin is supplied to an extruder and melted, and then the fiber is supplied. In general, a thermoplastic resin and fibers are mixed and kneaded in an extruder, extruded from a discharge port, cooled, and granulated. As the extruder, a single screw extruder and a twin screw extruder are used. However, compared with a single screw extruder, a twin screw extruder has higher productivity and freedom of operation. More preferably used.

  In the production of the above glass fiber reinforced thermoplastic resin pellets, the fibers are obtained by collecting about 300 to 3000 monofilaments having a diameter of 6 μm to 20 μm into one bundle and cutting them into 1 to 4 mm (hereinafter referred to as chopped strands). ). Since chopped strand fibers are more convenient for handling, when manufacturing fiber-reinforced thermoplastic resin pellets industrially, the thermoplastic resin is supplied to a twin screw extruder, and after the thermoplastic resin is melted, The most common method is to supply chopped strand fibers from the middle of a shaft extruder, mix and knead a molten thermoplastic resin and fibers, extrude the mixture, and cool and solidify.

  These composite materials are used in a wide range of fields such as mechanical mechanism parts, electrical parts, aircraft parts, ship parts, automobile parts, office parts, building materials, textile products, sundries, etc., but are reinforcing materials in resins. If the dispersion of the fibers is not uniform, problems such as product strength, shrinkage anisotropy, warping, and the like occur. Therefore, it is important to uniformly disperse the reinforcing material in the resin.

  If mixing and kneading in the twin-screw extruder is insufficient, the chopped strands will not be disassembled into monofilaments, and some or all of the chopped strands, which are in the state of monofilament aggregates, will remain in the resin composition pellets To do. If some or all of the chopped strands remain in the glass fiber reinforced thermoplastic resin composition pellets, in injection molding, some or all of the chopped strands are clogged in the gate, making injection molding impossible or injection molding. Even if it is possible, some or all of the chopped strands are present in the molded product, resulting in poor appearance or reduced function.

  In the method of supplying the glass fiber to the twin screw extruder in the monofilament state, the monofilament becomes cotton-like, the fluidity is lost, the resin cannot be fed out, and the nozzle opening is clogged.

  The present invention has been made to solve the above-described problems. First, chopped strands are defibrated into monofilament aggregates in advance. The monofilament becomes cotton-like when it is put into the twin screw extruder as it is, and the fluidity is remarkably lost. Therefore, after kneading with a thermoplastic resin in advance, a predetermined amount of the monofilament and a predetermined amount of the thermoplastic resin are compressed by a press or the like. Into a twin screw extruder.

  When the monofilament fiber and resin, which are normal methods, are supplied separately to the twin-screw extruder, the monofilament fiber itself becomes a cotton-like lump that does not slip into the screw and cannot be kneaded with the resin. By sending an appropriate amount of monofilament fiber, melting and kneading can be performed smoothly, and a thermoplastic resin composite material in which monofilaments are highly dispersed can be provided.

  In the thermoplastic resin composite material of the present invention, chopped strand fibers are defibrated in advance, mixed with a thermoplastic resin, compressed into a lump, melted and kneaded in a twin-screw extruder, and the monofilament is formed. Highly dispersed pellets can be produced. The thermoplastic resin composite molded product molded using this pellet is excellent in reinforcement effect, dimensional stability and fluidity, and is a mechanical mechanism part, electrical part, aircraft part, ship part, automobile part, office part, building material, etc. Used in a wide range of fields.

Enlarged photo of the residue obtained by firing the molded product produced in the example in the photo substitute drawing Dimensional comparison of molded product made in the example and molded product made with normal pellets

  As a thermoplastic resin, polyphenylene sulfide (manufactured by Tosoh Corporation, Sustile # 160, hereinafter referred to as PPS) was used. The fiber used was a glass fiber chopped strand CS (F) 3 manufactured by Nitto Boseki Co., Ltd.

  20 g of chopped strands are put in a mixer, 750 cc of water is poured and defibrated for 5 minutes. The defibrated glass fiber monofilament is dried at 100 ° C. to 120 ° C. for about 1 hour, and then kneaded with PPS so as to have a predetermined ratio is put in a metal container having a diameter of 10 mm and an internal volume of about 30 cc. Compress from about 10 MPa to form a lump with a diameter of about 10 mm.

  The agglomerated material was sequentially charged into a hopper of a twin screw extruder (manufactured by Technobell, KZW25TW-45MG-NH), melted, kneaded and pelletized.

  FIG. 1 shows a case in which a 50 mm square and 4 mm thick molded product is injection-molded using the pellets produced in the example and put in a crucible and heated to 700 to 800 ° C. with a burner to burn and eliminate PPS. It is the image image | photographed with the CCD camera made from HIROX. For comparison, a product obtained by similarly processing a molded product injection-molded using 40% PPS glass fiber pellets is shown.

  As shown in FIG. 1, it can be seen that in the example, the glass fiber is broken into monofilaments and is uniformly dispersed. On the other hand, in the case of using ordinary glass fiber reinforced resin pellets, there are glass fibers that are not completely defibrated into monofilaments, and the distribution is uneven.

  FIG. 2 shows the results of measuring the dimensions at the positions shown in the drawing of a 50 mm square molded article having a thickness of 4 mm injection molded using the pellets produced in the example. As a comparison, the results of measurement in the same manner for a molded product injection-molded using a commercially available PPS glass fiber 40% (manufactured by Tosoh Corporation, GS40-11A3) are shown.

  As can be seen from FIG. 2, in the example, the dimensional difference between the flow direction and the direction perpendicular to the flow is 1/5 or less of that formed using ordinary pellets, and the monofilament fibers are distributed uniformly and randomly. I understand.

  Table 1 shows the tensile test results (average value of 5 pieces each) of 1A dumbbell test pieces corresponding to JISK7162 using the pellets produced in the examples. As a comparison, the results of measurement in the same manner for a molded product injection-molded using the PPS glass fiber 40% pellets are shown.

  As can be seen from Table 1, it can be seen that the Examples have the same strength characteristics as the existing glass fiber reinforced resin.

Claims (1)

    A monofilament fiber having a length of 1 mm to 4 mm or a fiber obtained by chopping chopped strand fibers into a monofilament is mixed with an appropriate amount of thermoplastic resin, and the mixture is compressed by an appropriate amount with a press machine to form a lump, and then into a twin screw extruder. A method for producing thermoplastic resin pellets, characterized by being supplied, heated and kneaded.