JPH032011A - Preparation of fiber reinforced thermoplastic resin molded product - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a fiber-reinforced material for use in industrial materials such as automobile exterior panels, automobile structural materials, automobile parts such as battery trays, and building materials such as access proers. This invention relates to a method for manufacturing thermoplastic resin molded products. Specifically, the present invention relates to a molding method for obtaining a fiber-reinforced molded product with significantly less deformation due to fiber orientation and a good surface appearance by reinforcing the product at the same time as molding.

<Prior art> Several techniques have been known to obtain fiber-reinforced thermoplastic resin sheets, and the most typical method is injection molding using short fiber-reinforced pellets. This is a method for manufacturing fiber-reinforced molded products using a general molding method. There is also a method of manufacturing a fiber-reinforced molded product by injection molding or the like using a thermoplastic resin pellet reinforced with medium fiber length fibers having a length that is approximately the same as the pellet cutting length during pellet production.

On the other hand, in recent years, fiber-reinforced thermoplastic resin sheets have been reheated,
The so-called stampable sheet technology, in which products are obtained by press molding, is attracting attention. Stampable sheet technology can be broadly divided into two types depending on the fibers used for reinforcement. One is to produce a stampable sheet by mixing single fibers of several millimeters to 100 millimeters in length with thermoplastic resin powder in a wet or dry manner, heating and roll pressing, and then preheating and pressing this sheet. This is a method to obtain fiber-reinforced molded products. (For example, Japanese Patent Application Laid-Open No. 57-28135). Another stampable sheet technology is a long fiber reinforced stampable sheet. In this method, a molten thermoplastic resin is extrusion laminated onto a sealed long fiber mat, a stampable sheet is produced through roll pressing, this sheet is preheated, and a fiber-reinforced molded product is produced by press molding.

<Problems with conventional techniques> Each of the conventional techniques has its own technical and economic problems. The short fiber-reinforced pellet method, which is the most popular method for manufacturing fiber-reinforced molded products, has advantages over other technologies in terms of formability, design compatibility, cost, etc. It has the disadvantage that it is less effective in improving certain mechanical strength, particularly in terms of impact strength. The reason for this is that fibers are significantly cut during the mixing and dispersion process of fibers and resin, that is, during granulation, and during the plasticization and kneading process during molding. Furthermore, since the fibers flow in the mold together with the molten resin during the molding process, fiber orientation remains in the molded product and the molded product is easily deformed. In addition, in the case of fibers, especially inorganic fibers, significant wear of parts of the screws and cylinders of extruders and injection molding machines used in granulation, molding, etc. is also a major problem from the point of view of cost.

On the other hand, the manufacturing process of molded products using medium-length fiber-reinforced pellets requires a special extruder head, and the productivity is lower than that of short-fiber-reinforced pellets, resulting in high-cost products. Furthermore, deformation due to fiber orientation in the molded product and wear of screws, cylinders, etc. are the same as in the case of short fiber pellets.

For fiber reinforced stampable sheets with medium and long fiber length,
The fibers remaining in the molded product maintain the same length as the fibers used as raw materials, resulting in extremely high mechanical strength. However, in the technology of single fiber reinforced stampable sheets with medium fiber length, the thermoplastic resin raw material must be powder, and the product is expensive due to the grinding cost.

Furthermore, it requires expensive and special equipment such as a paper machine, roll press, and preheater. Fiber orientation within the molded product may occur and deform the molded product, although this is less than in the case of fiber-reinforced pellets, as some fibers flow together with the molten resin during molding.

In the case of a long-fiber stampable sheet, only the molten resin flows during molding, and the fibers do not flow, so that the outer periphery of the molded product is made up of only resin, making it unstable in terms of strength. In addition, since bundled fibers are used, the surface appearance tends to be rough, and like a medium-fiber stampable sheet, expensive and special equipment such as a fiber loom, extruder, roll press, and preheating machine is required.

Means for Solving the Problems> As described above, the conventional techniques have problems in mechanical properties, deformation, appearance, cost, etc., and cannot be considered as sufficient as industrial techniques. has been conducting intensive research to develop molding technology to overcome these problems, and has finally developed a new manufacturing method for fiber-reinforced thermoplastic resin molded products that is industrially superior and low cost, as described below. reached. That is, the present invention supplies a molten thermoplastic resin between at least two stacked porous fibrous sheets, and passes the resin through the voids of the fibrous sheets using resin supply pressure and/or press pressure. This is a method for producing a fiber-reinforced thermoplastic molded article, which is characterized by infiltrating a molten resin to the surface of a porous fibrous sheet made of continuous single fibers disposed as the outermost layer and molding the article.

In the present invention, a plurality of porous fibrous sheets are placed, molten resin is supplied between the fibrous sheet layers through holes provided in the porous fibrous sheets on the supply port side, and the entire surface of the molded product is formed by pressure molding. It is uniformly reinforced with fibers, the fibers are not cut, and the molten resin permeates between the sheet layers and flows toward the outermost sheet surface, so no air bubbles remain inside the molded product. A molded product with extremely high reinforcing effect can be obtained. In addition, since the fibers do not flow together with the molten fat during the molding process, no fiber orientation is observed, so there is no warping or deformation of the molded product, and the outermost layer of the porous fibrous sheet made of multiple stacked sheets. By using a continuous monofilament sheet, it is possible to obtain a deep-drawn product with a smooth appearance and excellent mechanical strength, which is highly demanded as an industrial product.
This is an innovative molding technology that allows fiber reinforcement during molding.

Hereinafter, an example of the molding method according to the present invention will be explained using the drawings.

For example, as shown in Figure 1, a plurality of porous fibrous sheets are placed in an unclosed mold, and molten resin is supplied between the fibrous sheet layers through a supply port in the mold. In this case, a hole large enough for the molten resin to pass through is provided at the same position as the supply port of the sheet on the supply port side of the layer to which the resin is supplied, and while the molten resin is supplied through the hole, or After the supply is completed, the mold is closed and molding is performed. Alternatively, the porous fibrous sheet may be placed in a closed mold and molten resin may be supplied through the holes.

In addition, as shown in Figure 2, a porous fibrous sheet on one side of the layer to which molten resin is supplied is placed in an unclosed mold, and molten resin is poured onto the sheet from the supply port outside the mold. After that, the other porous fibrous sheet is placed on the molten resin, the mold is closed, and the molded product is pressurized and cooled to obtain a fiber-reinforced molded product.

Alternatively, as shown in Figure 3, a fiber-reinforced molded product can also be obtained using a closed or open mold in which the molten resin supply port in the mold is located between the eyebrows of a plurality of porous fibrous sheets. be able to.

The porous fibrous sheet used in the present invention is made of inorganic fibers such as glass fibers, carbon fibers, and stainless steel fibers, organic fibers such as polyamide fibers, polyester fibers, and aramid fibers, and mixtures of inorganic and organic fibers. be able to. Especially in the case of glass fiber, a high reinforcing effect can be obtained at low cost. Generally available fibers having a diameter of 1 μm to 50 μm can be used. In addition, the porous fibrous sheet has a thickness of 3 to 50 to maintain its sheet shape.
-t% of a coagulant such as polyvinyl alcohol or epoxy resin may be used.

Thermoplastic resins used in the present invention include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and ABS.
Resins, common thermoplastic resins such as polyacrylonitrile, polyamide, polycarbonate, polyethylene terephthalate, mixtures thereof, polymer alloys, etc. are used. Furthermore, these thermoplastic resins may contain additives such as heat stabilizers and ultraviolet inhibitors, as well as colorants, inorganic fillers, and the like.

The plurality of porous fibrous sheets used for molding in the present invention may be a combination of the same or different types, and the combination can be selected depending on the application and required performance.

Furthermore, in the present invention, during the molding process, the molten resin flows through the gaps between the porous fibrous sheets under pressure, but the flow resistance is large, and especially in the case of inorganic fibers, heat is taken away by the fibers and the resin temperature decreases. Due to their large size, fluidity may be reduced and the permeability of the resin to the surface of the molded product may be insufficient. In order to prevent this, it is also effective to preheat the fibrous sheet used to, for example, 60° C. or higher before placing it between the molds.

<Examples> Examples of the present invention will be shown below, but the present invention is not limited thereto. The test methods for molded products in the examples are as follows.

Bending test: Conducted according to JIS K7203 using a three-point support method.

Falling weight impact test: Conducted using the apparatus shown in FIG.

A test piece (12) is placed on a test piece (14) of 50+aax 50mm x 2tnw+ thickness cut out from a glass fiber reinforced molded product, and a load (11) is dropped onto the test piece (12) from above to destroy the test piece. The lowest height under load (11) at that time was defined as the fracture height, and the resulting fracture energy was defined as the impact strength.

Fracture energy (kg-cm) = load (kg) x fracture height (cll) Deformation of molded product:
When the box-shaped molded product shown in Figure 4 is placed on a flat plate with its bottom facing down and each of the four corners is pressed separately onto the flat plate, the molded product deforms at the height of the remaining corner that is furthest from the flat plate. Quantity.

Surface Appearance of Molded ArticlesThe surface roughness of the molded articles was measured using a two-surface roughness meter (Super Roughness Meter SURFCOM, manufactured by Toyo Seimitsu ■).

Further, as a molding device, a vertical press molding machine having a side-feeding injection section and a mold clamping force of 200 tons was used to conduct a molding test. The mold consists of two parts: a convex upper mold and a concave lower mold.
Product wall thickness 2.111 with direct in-mold supply port for molten resin. Omm, product dimensions 2001+Im length x 200
A box-shaped product mold (Fig. 4) with a width of mm and a height of 40 mm was used.

(Example 1) A bundle of approximately 2,000 glass fibers with a diameter of 10 μm to which 0.2% by weight of vinyl silane was added as a binding agent was passed between two upper and lower metal rolls, and the fiber inlet side of the roll or 3-5m11 using a blower on the exit side
Air at a wind speed of +/sec is applied to the fiber bundle to defibrate the fiber bundle. The defibrated fibers are stacked and packed uniformly and without anisotropy on an iron plate with a wooden frame around the outer periphery, and a 10% aqueous solution of polyvinyl alcohol is sprinkled over it as a coagulant for the sheet. , then remove the wooden frame, 20
The mixture was dried and formed into a sheet in a heat press at 0°C to obtain a porous fibrous sheet (200 g/l) of long glass fibers.

Stack four of these porous fibrous sheets, and place the lower two porous fibrous sheets at the position of the molten resin supply port of the mold with a diameter of 1 mm.
A hole of 0 mm was made, and after preheating to 60"C, it was placed on the lower mold (Fig. 1 (A)). Thermoplastic resin (manufactured by Sumima Kagaku Kogyo) was melted between the eyebrows of the fibrous sheet through the liquid hole. , Tennoprene AX568: polypropylene resin, melt flow index 65 g/10 minutes) was supplied, and the pressure applied during molding was 100 kg/cm'' (Figure 1 (B)), as shown in Table 1. A molded product with extremely good mechanical strength was obtained.

(Comparative Examples 1 to 2) As the thermoplastic resin, Juju Noblen AX568 or glass fiber-filled polypropylene pellet, Namamugi Noblen GHH43C manufactured by Sumitomo Chemical Co., Ltd., glass fiber content 3
Molding was performed under the same conditions as in Example 1, except that a porous fibrous sheet was used (0wt%) and no porous fibrous sheet was used, and the physical properties, appearance, deformability, etc. of the molded product were compared with the molded product obtained in Example. evaluated.

As shown in Table 1, the strength was poor or the deformation was large.

<Effects of the Invention> As mentioned above, the fiber-reinforced molding technology of the present invention allows reinforcement at the same time as molding, making it possible to easily produce fiber-reinforced molded products with particularly excellent mechanical strength at a much lower cost than with conventional methods. Furthermore, various fibers can be combined according to the required performance of the product, making it possible to provide fiber-reinforced products for a wide range of applications such as automobile parts, home appliance parts, and building materials.

[Brief explanation of the drawing]

1 to 3 are longitudinal cross-sectional views of an apparatus illustrating the molding method of the present invention. 1. Upper mold 2. Lower mold 3, porous fibrous sheet 4, porous fibrous sheet 5, molten resin 6. Molten resin supply lower, portapull extruder Figure 4 is a perspective view of a molded product produced by the method of an embodiment of the present invention. Figure 5 is an impact test apparatus used in an embodiment of the present invention. 11. Load 12. Toughness 13. Refill tip R1/2 inch 14. Test piece 15. Test piece support (A) (A) Figure (B) (B) Z gold, 11

Claims (2)

[Claims] (1) A molten thermoplastic resin is supplied between at least two stacked porous fibrous sheets, and is passed through the voids of the fibrous sheets using resin supply pressure and/or press pressure to form the outermost layer. A method for producing a fiber-reinforced thermoplastic molded article, which comprises infiltrating a molten resin to the surface of a porous fibrous sheet made of continuous single fibers. (2) The method for producing a fiber-reinforced thermoplastic molded article according to claim 1, wherein the continuous single fibers are glass fibers.