JPH0584736A - Fiber reinforced thermoplastic resin composite sheet - Google Patents

Abstract

PURPOSE:To provide the title sheet used as a material for thermal press molding, excellent in mechanical strength and capable of also employing various thermoplastic resins. CONSTITUTION:Two kinds of base yarns 71, 72 are alternately arranged to be woven to form a composite sheet having a plain weave structure. Each of the base yarns 71, 72 is composed of a string like composite produced by applying a thermoplastic resin to the periphery of a core material formed from continuous fibers arranged side by side. By the use of this composite, the ratio of a resin to fibers can be arbitrarily set by adjusting the amount of the resin coated and the amount of fibers is increased to the uppermost limit to make it possible to obtain a molded product having excellent strength.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fiber-reinforced thermoplastic resin composite sheet suitable for hot press molding.

[0002]

2. Description of the Related Art Conventionally, a fiber-reinforced synthetic resin composite sheet using a thermoplastic resin as a base polymer has been known, but the problem that a thermoplastic resin is hard to be impregnated into a reinforcing fiber as compared with a thermosetting resin is a problem. there were. The reason for this is that thermosetting resins are usually liquid at room temperature and have excellent impregnating properties for reinforcing fibers, but thermoplastic resins do not become fluid unless they are heated, and the viscosity in the fluid state is high. In order to impregnate the reinforcing fiber, it is made into a fiber having a short fiber length like chopped strands finely chopped, and this and powdered thermoplastic resin are stirred with a mixer such as a Hensyl mixer. In general, a method of impregnating the sheet with a resin and then extruding the sheet into a sheet is used.

Also, as a resin that can be used, heat resistance,
At present, only polypropylene such as crystalline polypropylene and modified polypropylene has been put into practical use from the viewpoints of molding processability and raw material price.

[0004]

However, when the fibers and the resin are put into an extruder and kneaded and extruded, if the fiber content ratio is increased, extrusion molding becomes difficult, so that the fiber content ratio is limited. However, since a large amount of fibers cannot be contained and the fibers are cut by the screw of the extruder, there is a problem that it is not possible to obtain a product excellent in mechanical strength after all.

[0005] Also, with one type of resin that can be adopted, it is not possible to adequately meet the recent market demands for multifunctional and high-quality products in any product. There was also. INDUSTRIAL APPLICABILITY The present invention solves the above-mentioned drawbacks of the prior art, is excellent in mechanical strength, and is not limited to polypropylene in particular. Nylon, polyethylene, polycarbonate and other extrudable thermoplastic resins can also be adopted. The purpose of the invention is to provide a resin composite sheet.

Therefore, the present inventor has replaced the powdery resin used in the conventional molding of a fiber-reinforced thermoplastic resin composite sheet with a long continuous fiber (hereinafter referred to as "continuous fiber").
In addition, if a woven or knitted fabric with a thermoplastic resin that is heated and in a fluidized state is used as a base yarn,
The inventors have found that a composite sheet having a high fiber content and a well-balanced mechanical strength direction is obtained, and completed the present invention.

[0007]

According to the present invention, a large number of continuous fibers aligned in the longitudinal direction is used as a core material, and a cord-shaped composite body having a periphery thereof coated with a thermoplastic resin is used as a base thread. The gist is a fiber-reinforced thermoplastic resin composite sheet characterized by being woven or knitted.

Examples of the continuous fibers used in the present invention include glass fibers, aramid fibers, carbon fibers, boron fibers, vinylon fibers, polyamide fibers, polyester fibers, etc., and continuous fibers such as monofilaments, strands and yarns. However, it is preferable to use a resin having higher heat resistance than the coating resin described later. Then, it is preferable to subject these fibers to a surface treatment, and the term "surface treatment" as used herein refers to a generally-known primer treatment, in which continuous fibers and a thermoplastic resin coated thereon are used. It is a pretreatment adopted to improve the adhesiveness and is a surface treatment performed with a silane-based or borane-based coupling agent.

The thermoplastic resin used in the present invention includes polypropylene, polyethylene, polyester, polyamide, polystyrene, polycarbonate, polysulfone,
Polyvinyl chloride, chlorinated polyvinyl chloride and the like,
The point is that any resin that can be extrusion-coated can be used.
Further, these thermoplastic resins can be used alone or as a mixture of a plurality of them depending on the finally obtained molded article, and further, if necessary, a heat stabilizer, a plasticizer,
Antioxidants, pigments, lubricants, and other additives are mixed and used. In particular, in order to obtain a product with excellent rigidity, clay,
It is preferable to use an inorganic additive such as calcium carbonate.

In the present invention, a method for obtaining a base yarn composed of a string-like composite body in which a large number of continuous fibers are aligned in the longitudinal direction as a core material and the periphery thereof is coated with a thermoplastic resin is used. It is most preferable to adopt the extrusion molding method in terms of moldability, quality of the obtained product, etc.
A roving-like or strand-like continuous fiber composed of continuous fibers of several tens of μm is used, and a large number of this continuous fiber is pulled out in one direction from the bobbin while passing through an aligning device composed of, for example, an annular frame, The fibers are arranged in parallel or bundled in a shape. For example, as shown in FIG. 1, the bundled continuous fibers 4 are introduced into an extrusion coating device 3 in which a crosshead die 2 is attached to the tip of an extruder 1. Then, when the molten resin 5 is coated around the continuous fibers 4 at the exit of the crosshead die 2 and cooled and solidified by using the cooling device 6, the string-shaped composite body 7 can be continuously obtained. it can.

As another method, a powdery thermoplastic resin is adhered to the continuous fiber in advance, and this is also transferred in one direction in parallel or in a bundle, while the periphery thereof is covered with a thermoplastic resin film. There is a method of sequentially coating (laminating). Therefore, the amount of fibers in the string-shaped composite is
10 to 7 depending on the type, shape and thickness of the fiber used
The content is preferably 5% by volume, and if it is less than 10%, a sufficient reinforcing effect cannot be obtained, and if it exceeds 75% by volume, weaving or knitting in the subsequent step becomes difficult.

The cross-sectional shape and size of the string-shaped composite body are not particularly limited, but may be selected depending on the type of weaving machine or weaving machine used in the subsequent step of weaving or knitting, the type of resin or fiber used, and the like. Although it has a property that can be appropriately set depending on the element, for example, various shapes such as a rectangular shape having a sectional shape as shown in FIG. 2, a circular shape, an elliptical shape, and the like can be cited.

The method of weaving or knitting into a sheet using the cord-shaped composite obtained as described above is not particularly limited, and a conventionally known method can be adopted. The type of weave includes, for example, plain weave, satin weave, satin weave, etc., and may be woven into a desired sheet by using various ready-made weaving machines and knitting machines. Further, as the method of weaving and the like, not only the machine weaving as described above but also a manual method such as when knitting a colander using a split bamboo as the material may be mentioned. It is not necessary to carefully weave thin threads over time, and the point is to use a woven structure just like canvas. FIG. 3 shows an example of the composite sheet 8 of the present invention woven by plain weaving using the cord-shaped composite body 7 shown in FIG. This composite sheet 8 shows an example in which the warp and weft base yarns are woven by alternately arranging two types of base yarns 71 and 72 respectively coated with different kinds of resins.

When performing hot press molding using the fiber-reinforced thermoplastic resin composite sheet of the present invention, the molding machine used can be the one used for stamping molding as it is, and the mold is usually the upper or lower mold. It is composed of two molds and is a system in which a composite sheet is inserted, closed and pressed in a heated state. Further, in the press molding, it is optional to stack the composite sheet of the present invention with another material, for example, a thermoplastic resin sheet such as a polypropylene sheet to obtain a laminate.

[0015]

The fiber-reinforced thermoplastic resin composite sheet of the present invention is
It is made by weaving or knitting in a sheet shape with a core material made up of a large number of continuous fibers aligned in the longitudinal direction, and a string-like composite having the periphery coated with a thermoplastic resin as a base yarn. Therefore, the ratio of fiber to resin in the composite can be freely changed by adjusting the amount of coating resin in the base yarn. Further, if the extrusion molding method is adopted for molding the base yarn, continuous molding is possible. Further, since the sheet is formed by weaving or knitting, the forming speed is not significantly affected by the ratio of fiber to resin.

Further, since the stampable sheet used for stamping molding is made of short fibers, it is inevitable to use a relatively thick laminated sheet as a raw material, and only a thick product can be produced. However, the composite sheet of the present invention is Since the continuous fiber is used, it can be made thin and can be manufactured from a thin product having a thickness of about 0.5 mm.

[0017]

EXAMPLE An example of the present invention will be described below.
The ten cross-twisted glass fibers (0.3 mm diameter) pretreated with a silane coupling agent are aligned in a plane and continuously transferred in one direction, while the crosshead die shown in FIG. 2 and around it, a melted polypropylene resin 5 from the extruder 1 is separately coated at the outlet of the die 2 to form a string-shaped composite 7 having a coating thickness of 0.5 mm as shown in FIG. Obtained.

Next, the composite 7 was woven on a plain loom to form a composite sheet 8 as shown in FIG. Two sheets 8 thus obtained were stacked, a hemispherical mold was attached to a heat press machine, the mold temperature was set to 240 ° C., the sheets were loaded into this mold, and press-molded to form meat. Thickness is 1.9mm
The bowl-shaped molded product of was molded.

Next, a test piece having a width of 10 mm and a length of 100 mm was cut out from the obtained molded product, and a tensile strength and an Izod impact strength were obtained together with a bowl-shaped molded product having the same wall thickness and considered to be produced by a conventional method. As a result of measuring the impact strength by the same method as described above, in the case of the product of the present invention, 1300 k
The values were g / cm ² and 120 kg · cm / cm. On the other hand, the conventional products are 700 kg / cm ² and 85 kg · c.
It was m / cm.

[0020]

The fiber-reinforced thermoplastic resin composite sheet of the present invention has a string-shaped composite body in which a large number of continuous fibers are aligned in the longitudinal direction as a core material and the periphery thereof is coated with a thermoplastic resin. Since the base yarn is woven or knitted into a sheet, the ratio of fiber to resin in the composite can be freely changed by adjusting the amount of coating resin in the base yarn. Further, if the extrusion molding method is adopted for molding the base yarn, continuous molding is possible. Further, since the sheet is formed by weaving or knitting, the forming speed is not significantly affected by the ratio of fiber to resin.

Further, since the stampable sheet used for stamping molding is made of short fibers, it is unavoidable to use a relatively thick laminated sheet as a raw material, and only a thick product can be produced. However, the composite sheet of the present invention is Since the continuous fiber is used, it can be made thin and can be manufactured from a thin product having a thickness of about 0.5 mm. Therefore, the material of the string-shaped composite sheet, which is the material forming the composite sheet, can be selected and used in a wide range, so that it is possible to easily mold the material having the quality required in the market.

Further, since the composite sheet to be pressed is woven or knitted, it is possible to obtain an excellent mechanical strength balance in the longitudinal and transverse directions, and also to provide strength in the thickness direction. However, delamination or the like in the reinforcing fiber layer, which is often seen in laminated bodies and the like, cannot occur.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view showing only an essential part of an apparatus for manufacturing a base yarn used in the present invention.

FIG. 2 is a partially cutaway perspective view showing a cross-sectional state of a base yarn formed by using the device shown in FIG.

FIG. 3 is a perspective view showing an example of the composite sheet of the present invention woven using the base yarn shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 2 Crosshead die 3 Extrusion coating device 4 Continuous fiber 5 Molten resin 7 String-like composite 8 The composite sheet of the present invention 71 Base yarn 72 Base yarn

Claims (1)

[Claims] 1. A woven or knitted product, comprising a core material comprising a large number of continuous fibers aligned in the longitudinal direction, and a cord-shaped composite body having a periphery coated with a thermoplastic resin as a base yarn. Fiber-reinforced thermoplastic resin composite sheet characterized by: