JPH03261519A - Manufacture 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 relates to a method for manufacturing fiber-reinforced thermoplastic resin molded products for use in automobile parts such as automobile exterior panels and interior panels, and industrial materials such as civil engineering and construction materials. .

More specifically, the present invention relates to a method for producing fiber-reinforced thermoplastic resin molded articles that are less deformed due to fiber orientation and have excellent appearance gloss, dimensional stability, and mechanical properties.

<Prior art> Several methods have been known to obtain fiber-reinforced thermoplastic resin molded products. The most representative method is to use short fiber-reinforced pellets to obtain a molded product using a general molding method such as injection molding. This is a method for manufacturing fiber-reinforced molded products.

There is also a method of producing a fiber-reinforced molded product by injection molding or the like using thermoplastic resin pellets reinforced with medium fiber length fibers that are approximately the same length as the pellet cutting length during pellet production. On the other hand, in recent years, a so-called stamped sheet technology has been attracting attention, in which a fiber-reinforced thermoplastic resin sheet is reheated and a product is obtained by press molding. Stamped sheet technology can be broadly divided into two types depending on the fibers used for reinforcement. One is to mix single fibers of several sat to 100 lengths with thermoplastic resin powder in a wet or dry process, heat and roll press to produce a stamped sample sheet, and then preheat this sheet and press it. This is a method to obtain fiber-reinforced molded products. (For example, Japanese Patent Application Laid-open No. 57-28135),
Another stamped sample sheet technology is long fiber reinforced stamped sample sheets. In this method, a woven long fiber mat is extrusion laminated with a molten thermoplastic resin, a stampable sheet is produced through roll pressing, this sheet is preheated, and a fiber-reinforced molded product is produced by press molding.

<Problem to be solved by the invention> 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 moldability, design compatibility, cost, etc. It has the disadvantage that it is less effective in improving certain mechanical strengths, especially impact strength. The reason for this is that the fibers are significantly cut during the mixing and dispersion process of the fibers and resin, that is, during the plasticization and kneading process twice, once during granulation and 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, resulting in large deformation of the molded product.

In addition, in the case of fibers, especially non-molecular fibers, it is a big problem from the point of view of cost that parts of the screws and cylinders of extruders and injection molding machines used in granulation, molding, etc. are significantly worn out.

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

This is the same as in the case of

Fiber-reinforced stampable sheets with medium and long fiber lengths have extremely high mechanical strength because the fibers remaining in the molded product maintain the same length of fibers used as raw materials. 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 preheating machine. 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, since 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 converged fibers are used, only a rough surface appearance can be obtained, and like stampable sheets with medium fiber length, expensive and special equipment such as a fiber loom, extruder, roll press, and preheating machine are required. .

In addition to the above, the surface appearance and gloss of fiber-reinforced thermoplastic resin molded products are significantly inferior to those of non-reinforced molded products because fibers are partially exposed on the surface. Furthermore, thermoplastic resins have a large coefficient of linear expansion, and when bonded to metal, there is a problem that the dimensions change due to temperature differences.

As described above, the conventional techniques have problems in mechanical properties, deformation, appearance, cost, etc., and cannot be said to be sufficient as industrial techniques. The inventors have been conducting intensive research to develop a technology to overcome these problems, and have finally developed the following industrially superior, low-cost, fiber-reinforced thermoplastic resin molding with an excellent surface appearance. This led to the development of a new manufacturing method for the product.

That is, the present invention provides (i) a molten thermoplastic resin (A)
is supplied between the layers of a plurality of porous fibrous sheets, and the thermoplastic resin (A) is infiltrated through the voids of the porous fibrous sheets by resin supply pressure and/or press pressure to form the porous fibrous sheets. The thermoplastic resin (A
) and a sheet or film made of a thermoplastic resin CB) having adhesive properties. (A) is supplied, and a sheet or film made of a porous fibrous sheet and a thermoplastic resin (CB) having adhesive properties with the thermoplastic resin (A) is stacked on top of the thermoplastic resin (CB) in which the porous fibrous sheet is melted. The sheet or film made of the thermoplastic resin (B) is prepared by placing the sheet facing A), closing the mold, and allowing the molten thermoplastic resin (A) to penetrate through the voids in the porous fibrous sheet. A method for manufacturing a fiber-reinforced thermoplastic resin molded article, characterized in that (ii) a thermoplastic resin (
A film or sheet made of a thermoplastic resin (8) having adhesive properties with A) is placed, and then a molten fiber-reinforced thermoplastic resin containing the thermoplastic resin (A) as a matrix material is fed into the mold. Alternatively, a method for producing a fiber-reinforced thermoplastic resin molded article is characterized in that after supplying, the mold is closed and the molded article is cooled under pressure.

Hereinafter, an example of the molding method according to the present invention will be explained using the drawings. An example of this is as shown in Figure 1.2, a film consisting of a plurality of porous fibrous sheets (3) and a thermoplastic resin (A) and a thermoplastic resin (B) that has adhesive properties under pressure. Alternatively, after placing the sheet (4) in a closed or unclosed mold, the molten thermoplastic resin (A) is supplied between the layers of the porous fibrous sheet (3), and the resin supply pressure and/or This is a method in which a molten resin is permeated through the voids of a porous fibrous sheet by press pressure, and is bonded to a sheet or film (4) made of a thermoplastic resin (B) to form the sheet.

In addition, Figure 3.4 shows that the thermoplastic resin (A) is supplied into the mold, and the porous fibrous sheet (3) and the thermoplastic resin (B) are
The mold is closed so that the porous fibrous sheet (3) faces the molten thermoplastic resin (A), and the voids in the porous fibrous sheet (3) are stacked. This is a method in which a molten thermoplastic resin (A) is infiltrated through a thermoplastic resin (B), and then adhered to a sheet or film (4) made of a thermoplastic resin (B) to form the resin.

Figure 5.6 shows thermoplastic resin (B) in an unclosed mold.
A film or sheet (4) consisting of i! Then, after supplying a molten fiber-reinforced thermoplastic resin containing the thermoplastic resin (A) as a matrix material into the mold, or after the supply is finished, the mold is closed and cooled under pressure. be.

The sheet or film made of the thermoplastic resin (B) used in the present invention includes polyethylene, polypropylene, polystyrene, acrylonitrile-styrene-butadiene copolymer, polyvinyl chloride, polyamide, polycarbonate, polyester, polyethylene terephthalate, polybutylene terephthalate, These are sheets or films made of thermoplastic resins such as polyphenylene ether, mixtures thereof, and polymer alloys using these thermoplastic resins.

The material of the porous fibrous sheet used in the present invention includes inorganic fibers such as glass fiber, carbon fiber, and stainless steel fiber;
Also, organic fibers such as boria fibers, polyester fibers, aramid fibers, and mixtures of inorganic and organic fibers can be used. 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.

The porous fibrous sheet in the present invention may be one using a coagulant such as 0.5 to 50w LX polyvinyl alcohol or epoxy resin in order to maintain the sheet shape, or it may be a simple sheet shape. Alternatively, a sheet preformed into the shape of a molded article may be used; on the other hand, the fiber length of the discontinuous monofilament sheet may be 100 m.
m or less, and more preferably from 1 to 50 m+- from the viewpoint of manufacturing the single fiber sheet and the mechanical strength obtained.
The plurality of 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.

The thermoplastic resin (A) used in the present invention is polyethylene, polypropylene, polystyrene, acrylonitrile/styrene/butadiene copolymer, polyvinyl chloride, polyamide, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene ether, styrene/acrylonitrile polymer. Thermoplastic resins such as, mixtures thereof, polymer alloys using these thermoplastic resins, etc. are used. Furthermore, by incorporating inorganic fillers such as curk, wollastonite, and glass fiber into these thermoplastic resins, the molding shrinkage rate can be reduced to 10/1.
000 or less, and the bending elastic modulus is 24,000 kg/cm”
The above may also be used. These thermoplastic resins may contain additives such as heat stabilizers and ultraviolet inhibitors, as well as colorants, rubbers, and the like.

When using a fiber-reinforced thermoplastic resin, preferably 1
A resin in which relatively long fibers having a length of m+i to 50+im are dispersed is used. In order to obtain such a resin, there is a method of using pellets in which medium-length fibers are dispersed, but in this case, the fibers are significantly cut during the plasticization process of the molding machine, and no improvement in mechanical strength can be expected.

For this reason, the inventors of the present invention devised a plasticizing device shown in FIG. The plasticizing device consists of a heating cylinder (12) and a heating cylinder (II).
) consists of a screw.

(8) is a thermoplastic resin supply port, and (9) is a fiber supply port, and a quantitative fiber supply device such as a roving cutter is provided on the outside. (10) is a deaeration port, which deaerates air, etc. taken in with the fibers. (13) is the nozzle of the plasticizing device. The screw length/screw diameter ratio is at least 1
5 or more, a fiber supply port is provided in the center of the cylinder, and a deaeration port is provided closer to the nozzle than the fiber supply port. Furthermore, a device (see Fig. 8) with the tip of the nozzle connected to an accumulator (
Figure 9) is used. In the accumulation letter of FIG. 8, (21) is a connection port with a plasticizing device, through which molten resin is supplied. (14) is a hydraulic piston cylinder, (
15) is a molten resin cylinder, and (16) and (17) are pistons. (18) is a support frame that supports (14) and (15). (19) The piston is moved by the oil flowing in and out through the inlet and outlet port in (20).The molten resin stored in the cylinder in I5) is injected from the discharge port in (22).

By using this apparatus (FIG. 9), it is possible to obtain a molten resin in which long fibers are dispersed, which is unprecedented, and a product with extremely high mechanical strength and low cost can be obtained. If the screw length/screw diameter ratio is I5 or less, the length from the central I & i1m supply port to the deaeration port,
Also, the length from the fiber supply port to the nozzle tip is too short, resulting in insufficient dispersion of the fibers introduced into the molten resin and insufficient deaeration.

In the present invention, the fibers inputted from the fiber supply port of the plasticizing device can be either single fibers or bundled fibers made by binding tens to hundreds of single fibers with a binding agent, and 1 m
The fibers may be roughly cut from m to 50 mm, or long fibers may be cut and fed at the fiber supply port.The materials are as follows:
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 can be used.

In the present invention, during the molding process, the molten resin flows through the gaps between the porous fiber sheets due to pressure, but the flow resistance is large, and especially in the case of inorganic fibers, the heat is carried away by the fibers, resulting in a large drop in resin temperature, so the molten resin flows. However, the permeability of the resin to the surface of the molded product may be insufficient.
In order to prevent this, it is effective to preheat the fibrous sheet to, for example, 60° C. or higher before placing it in the mold.

<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 in accordance with JIS K7203 using a three-point support method. The test piece was 2IIIO + thickness x 1 cut out from the bottom and rib parts of the box-shaped molded product shown in Figure 11.
The test was carried out under the condition of 23°C using a piece with a width of 0 mm and a length of 90 mm.

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

50oiX50+ cut out from glass fiber reinforced molded product
+wX2+am thick test piece (30) with striking core (2
), and a load (28) is dropped from above onto the striking core (29), and the load (28) at which the test piece is destroyed is
The lowest height of the specimen was taken as the fracture height, and the fracture energy obtained by the formula below was taken as the impact strength.

Fracture energy (Kg-cm) = Load (Kg) x Fracture height (cs+) Deformation of the molded product: Place the box-shaped molded product shown in Figure 10 on a flat plate with the bottom facing down, and separate each of the four corners separately. When pressed onto a flat plate, the height of the remaining corners farthest from the flat plate was defined as the amount of deformation of the molded product.

Surface appearance of molded product: The surface roughness of the molded product was measured using a surface roughness meter (super roughness meter StlRFCOM, manufactured by Toyo Seimitsu ■).

(Example 1) A molding test was conducted using a vertical press molding machine having a mold clamping force of 200 tons. The mold consists of two parts, an upper mold and a lower mold, and the lower mold has a 2 mm diameter in-mold supply port for the molten resin in the center and a manifold as a part connected thereto. The mold used was product direction L2.0III, product dimensions 200mm length x 200m prefecture width x 40111
A box-shaped molded product (FIG. 10) with a height of 11 was used.

First, two 300μ thick extruded sheets made of pp/EPDM/nylon 6 (Flexroy@D-2000 manufactured by Sumitomo Chemical Co., Ltd.) were placed, and Cumulus sheet manufactured by Nippon Vilene Co., Ltd. was used as a porous fibrous sheet. V.H.M.
Eight sheets of 5075 were placed one on top of the other. Among these, two extruded sheets and four fibrous sheets on the lower side had a hole with a diameter of 10 mm at the position of the molten resin supply port. Fiber sorting is 60°
The one preheated to C was used. Furthermore, two sheets of Flexloy@D-2000 were placed on top of it, and a thermoplastic resin (polypropylene resin manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen@AX568) was melted between the layers of the fibrous sheet through the holes.
(ethylene-propylene copolymer, melt flow index: 65 g, 710 minutes) was supplied, and molding was performed at a pressure of 100 kg/cm" on the resin. As shown in Table 1, surface gloss, dimensional stability, and mechanical strength were obtained. An excellent molded product was obtained.

(Example 2) The thermoplastic resin was polypropylene resin manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noprene@BWH44 (containing 40% talc,
Molding shrinkage rate 8/1000, bending elastic modulus 52000Kg/
The molding was carried out using a molding method (cj). All other conditions were the same as in Example 1, and the test was conducted. As shown in Table 1,
A molded article with excellent surface gloss, dimensional stability, and mechanical strength was obtained.

(Example 3) Melted thermoplastic resin (Sumitomo Noblen@BWH44) was supplied from the resin supply port onto the lower mold, and then 8 porous fibrous sheets (Cumulus Sheet VHM5075 manufactured by Nippon Vilene Co., Ltd.) were and a sheet made of thermoplastic resin (Flexroy D-2000 manufactured by Sumitomo Chemical Co., Ltd.)
The two sheets were placed one on top of the other, the mold was closed, and molding was performed. As shown in Table 1, the molded product had excellent appearance and mechanical strength.

(Example 4) First, two sheets of Flexloy@D-2000 (a hole with a diameter of 10 mm was created at the position of the resin supply port) were placed in a mold.

It has a full-fract quib screw with a diameter of 50 Iiffl and a screw length/screw diameter ratio of 29.
, using a plasticizing device consisting of a matrix resin supply port at the rear of the cylinder, a fiber material supply port in the center, and a deaeration port in the middle of the fiber material supply port and the nozzle.
Polypropylene resin Sumitomo Noblen AX56B (melt flow index 65 g/io min) was introduced from the matrix resin supply port, and Nippon Glass Fiber ■ was added as a fiber material.
Made of glass fiber roving RER231-3M
14 was cut into a length of 13o using a roving cutter, and an amount of polypropylene resin with a filling amount of 30% by weight was added from the fiber material supply port, and the obtained long fiber-dispersed molten resin was filled into an accumulator. The molten resin was supplied through a hole provided in the sheet onto a sheet of thermoplastic resin already placed through a molten resin supply port in the mold, and the mold was closed to perform molding. As shown in Table 1, the molded product had excellent appearance and mechanical strength.

(Comparative Example 1) Sheet made of thermoplastic resin (Flexroy@D-2
Molding was carried out without using 0(10). All other conditions were the same as in Example 1, and the test was conducted.

(Comparative Example 2) Molding was performed without using a porous fibrous sheet or a sheet made of thermoplastic P4 resin. All other conditions are Example 1
The test was conducted under the same conditions.

<Effects of the Invention> As in the present invention, a film or sheet made of a thermoplastic resin (A) and a thermoplastic resin (B) having adhesive properties is used as the outermost layer, and is combined with a fibrous sheet or a fiber-reinforced thermoplastic resin. By doing so, it is possible to obtain a product with high rigidity, no deformation, and a beautiful resin surface appearance. Furthermore, the molding shrinkage rate of the obtained product is extremely small and has no anisotropy.

As mentioned above, by using the fiber-reinforced molding technology of the present invention, reinforcement can be achieved at the same time as molding, and fiber-reinforced molded products with particularly beautiful surface appearance and excellent mechanical strength can be easily obtained at extremely low cost compared to conventional methods. It is also possible to combine various fibers according to the required performance of the product.
This makes it possible to provide fiber-reinforced products for a wide range of applications, such as home appliance parts and building materials.

[Brief explanation of drawings]

1 to 6 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) Film or sheet made of thermoplastic resin (B) (5a) Melted thermoplastic resin (5b) Melted fiber reinforced heat Plastic resin (6) Molten resin supply port (7) Portable extruder FIG. 7 shows a sectional view of a plasticizing device for kneading matrix resin and fibers in the present invention. (8) Matrix resin supply port (9) Fiber material supply port (10) Deaeration port (11) Screw (12) Cylinder (13) Nozzle Figure 8 is a cross-sectional view of the accumulator used in the example of the present invention. be. (14) Hydraulic cylinder (15) Molten resin cylinder (16) Hydraulic piston (17) Molten resin piston (18) Cylinder fixture (19) Oil inlet/outlet (20> Oil inlet/outlet (21) Molten resin supply port (22) Molten resin cylinder nozzle Figure 9 is a connection diagram of the plasticizing device, accumulator, and mold used in the embodiment of the present invention. (23) Plasticizing and kneading device (24) Accumulator rake - (25) Top Mold (26) Lower mold (27) Manifold portion FIG. 10 is a perspective view of a box-shaped molded product without ribs, made by the method of the embodiment of the present invention, and FIG. 11 is a box-shaped molded product with ribs. Fig. 12 is the device used for the falling weight impact test. (28) Load (29) Percussion core (30) Test piece (31) Test piece support (32) i! Core tip R (1/2 inch) (a) (1)) Fig. (6) (fi) (6) (1)) Fig. (J) (1)) Fig. (d) (1)) Fig. ( a) (1)) Figure 8 25 Figure No.

Claims (4)

[Claims] (1) A molten thermoplastic resin (A) is supplied between the layers of a plurality of porous fibrous sheets, and the thermoplastic resin (A) is passed through the voids of the porous fibrous sheets by resin supply pressure and/or press pressure. The fiber reinforcement is characterized in that it is bonded to a sheet or film made of a thermoplastic resin (B) which is located on the outermost layer surface of a porous fibrous sheet and has adhesive properties with the thermoplastic resin (A). Method for manufacturing thermoplastic resin molded products. (2) A sheet or film made of a porous fibrous sheet and a thermoplastic resin (B) that has adhesive properties with the thermoplastic resin (A) by supplying the molten thermoplastic resin (A) into an unclosed mold. The porous fibrous sheets are stacked and placed so that they face the molten thermoplastic resin (A), the mold is closed, and the molten thermoplastic resin (A) is passed through the voids of the porous fibrous sheets.
) and adhering it to a sheet or film made of thermoplastic resin (B). (3) A thermoplastic resin (A) having a molding shrinkage rate of 10/1000 or less and a flexural modulus of 24000 kg/cm^2 or more is used. A method for manufacturing a fiber-reinforced thermoplastic resin molded product. (4) A film or sheet made of a thermoplastic resin (A) and a thermoplastic resin (B) having adhesive properties is placed in an unclosed mold, and then the thermoplastic resin (A) is used as a matrix material. A method for producing a fiber-reinforced thermoplastic resin molded article, which comprises supplying or after supplying a molten fiber-reinforced thermoplastic resin into a mold, closing the mold and cooling under pressure.