JPH0376614A - Manufacture of molded object of fiber reinforced thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain uniform strength and low production cost by a method in which the molten thermoplastic resin in which the fiber having the average fiber length in prescribed ranged is dispersed as reinforcing material, is fed into an unclosed mold, and then the mold is closed and the resin is pressurized and cooled. CONSTITUTION:The molten thermoplastic resin in which the fiber having the average fiber length of at least 1 mm and at most 50 mm is dispersed as reinforcing material, is fed in an unclosed mold, and then the mold is closed and the resin is pressurized and cooled, thereby obtaining a molded object. As the used fiber material for reinforcement, the inorganic fiber such as glass fiber, carbon fiber and stainless fiber etc., or the organic fiber such as polyamide fiber, polyester fiber and aramid fiber etc., and the mixture of the inorganic fiber and the organic fiber may be used. Consequently the impact resistant strength of a product is improved, and the whole part of the obtained product is reinforced with long fibers.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to fiber-reinforced thermoplastic resin molding for use in automobile parts such as automobile exterior panels, automobile structural materials, battery trays, and industrial materials such as civil engineering and construction materials. Concerning the manufacturing method of the product. Specifically, the present invention relates to a method for producing a fiber-reinforced thermoplastic resin molded product that is less deformed due to fiber orientation, has a good surface appearance, and has excellent mechanical strength.

<Prior Art> Conventionally, a typical method for manufacturing fiber-reinforced thermoplastic resin molded articles is to mold short fiber-reinforced resin pellets using a general molding method such as injection molding. There is also a method of manufacturing fiber-reinforced molded products by injection molding, etc. using thermoplastic resin pellets reinforced with fibers of medium fiber length (fiber length 10 ma or less), which is approximately the same length as the pellet cutting length during resin pellet production. be.

<Conventional technology! ! > Each of the conventional technologies has its own technical problems. The short fiber-reinforced resin pellet method, which is the most common method for manufacturing fiber-reinforced molded products, has the disadvantage that the improvement effect on mechanical strength, especially impact strength, which is the most important purpose of fiber reinforcement, is small. The reason for this is that the fibers are cut into extremely short lengths during the mixing and dispersion process of the fibers and resin, that is, during the granulation process and the plasticization and kneading process twice during injection molding. Furthermore, during the injection molding process, the fibers flow together with the molten resin within the narrow cavity clearance in the mold, undergoing significant shearing, resulting in further fiber breakage. Even if the fibers are long, they are subjected to significant shearing during the plasticization process during injection molding and the flow process in the mold, and the fibers are cut into short lengths, resulting in the fiber length in the molded product being about the same as that of short fiber-reinforced resin, which reduces impact resistance. The improvement effect is small.

<Means for solving the problem> In this way, although the conventional technology is filled with fibers,
The desired mechanical properties have not been improved sufficiently, and it cannot be said to be a sufficient industrial technology. However, we finally came to the invention of a new manufacturing method for industrially excellent fiber-reinforced thermoplastic resin molded articles, which will be described below.

That is, in the present invention, a molten thermoplastic resin in which fibers with an average fiber length of 1 mm or more and a valence of 50 or less are dispersed as a reinforcing material is supplied into an unclosed mold, the mold is closed, and pressure is applied. The present invention relates to a method for manufacturing a fiber-reinforced molded product, which is characterized in that the molded product is obtained by cooling.

To explain the present invention in more detail, in the present invention, a molten resin in which fibers having a length of 1 to 50 mm are dispersed is supplied into an open mold, and shaped by mold clamping pressure. For this reason, the supply pressure from the plasticizing device is significantly lower at 100-300 kg/c+a compared to 500-1600 kg/ct for injection molding, and the mold clamping pressure required for shaping is also 30-150 kg/ct. ci is extremely small, and the amount of cutting of fibers dispersed in the molten matrix resin is significantly less than in injection molding.

In addition, the molded product obtained by this molding method has greatly improved impact resistance strength, and it is possible to obtain a product in which all parts of the molded product are reinforced with long fibers.

Next, in the present invention, in order to prevent the fibers from being cut during the plasticizing step, it is necessary that the shear is as small as possible, and for example, a plasticizing device as shown in FIG. 1 can be preferably used. (1) is a supply port for supplying thermoplastic resin raw material, (2) is a supply port for supplying fiber material, (
3) shows a vent hole for removing gas contained in the resin.

Cutting of fibers in the plasticizing process of fiber-reinforced resin mainly occurs in the first half of the plasticizing device, that is, in the resin pellet supply section and the compression section. It is applied after the compression section, that is, after the thermoplastic resin has sufficiently melted. Furthermore, since air is drawn into the molten resin together with the supplied fibers, air can be effectively degassed by providing a vent between the fiber supply port and the cylinder nozzle.

In addition, since the supplied fibers need to be uniformly dispersed in the molten resin, it is necessary to have a kneading process as long as possible after adding the fibers into the resin. ratio of at least 15
By using this device, it is possible to obtain a resin in which long fibers are uniformly dispersed with very little fiber breakage, and by using the method of molding by opening the mold described above. Fiber breakage within the mold is also extremely reduced, and the resulting molded product is uniformly reinforced with long fibers.

The reinforcing fiber materials used in the present invention include inorganic fibers such as glass fibers, carbon fibers, and stainless steel fibers, organic fibers such as boria fibers, polyester fibers, and aramid fibers, and mixtures of inorganic fibers and organic fibers. can do. In the case of glass fibers, those whose surface has been treated with general organic silicon compounds such as amofusilane and vinylsilane may be used, and commonly available fibers having a fiber diameter of 1 μm to 50 μm can be used.

In the present invention, the fibers supplied to the fiber supply port in the center of the cylinder of the plasticizing device have a fiber length of 1 mm to 50 mm.
Single fibers or bundled fibers obtained by binding tens to hundreds of single fibers with a binding agent can be used. Fiber length is 1m
If it is smaller than m, the effect of improving the mechanical strength, especially impact strength, of the molded product will be small, and if it is larger than 50 mm, the fibers will cause a bridging phenomenon at the fiber material supply port.
Fiber supply is not going smoothly.

Thermoplastic resins used in the present invention include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and ABS.
Common thermoplastic resins such as resin, boria 5, polycarbonate, polyethylene terephthalate, modified products thereof, 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.

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

- Bending test The test was conducted using the three-point support method in accordance with JIS K675B. The test piece was cut out from the bottom of the box-shaped molded product shown in Figure 4, and had a shape of 2 mm thick x 10 mm wide x 90 mm.
The test was conducted in an atmosphere of 23°C using a long one.

- Impact B test In accordance with JIS K6758, the Izot-Notch method was tested. The test piece was cut out from the bottom part of the box-shaped molded product shown in Figure 4, and was 2m thick x 10m wide x
The test was conducted in an atmosphere of 23°C using a 90ffIIB length.

- Place the molded product obtained with the average fiber length on an iron plate, heat it with a burner for about 1 hour, and then leave it in an electric furnace at 500°C for 2 hours to remove combustible components such as thermoplastic resin. After cooling, the length was measured for 200 samples extracted from any part. The total average fiber length was calculated and taken as the average fiber length.

・Fiber filling amount Cut a sample of size 2'Om x 20m from the molded product and measure its weight before heating and combustion, then remove combustible components and take out only the fibers using the same method as for measuring the average fiber length. The weight after heating and combustion is measured, and the fiber filling amount is calculated in percent using the following formula.

Example 1 A mold having an internal supply port for molten resin was installed in a vertical press having a mold clamping force of 100 tons, an accumulator shown in Fig. 2 was connected to the manifold of this mold, and The plasticizing device shown in FIG. 1 was connected to an accumulator. The plasticizing device used here has a full-fract type screw with a diameter of 50 mm, the ratio of screenie length/screw diameter is 29, a matrix resin supply port (1) at the rear of the cylinder, and a fiber material supply port in the center. The structure is such that it has a deaeration port (3) located between the fiber material supply port (2) and the nozzle. Furthermore, a vacuum pump was connected to the deaeration port (3) to perform forced deaeration. Figure 3 shows the overall connection diagram. The mold consists of two parts, an upper and a lower part.The mold has a box-shaped shape with a diameter of 3IIIl and an in-mold supply port for molten resin in the center of the lower mold, a product wall thickness of 2m + a, and product dimensions of 200mm length x 200mm width x 40m height. A mold with

(Fig. 4) As the thermoplastic resin, Sumitomo Chemical Co., Ltd.'s polypropylene resin, Sumitomo Noprene AX568 (melt flow index 65 g/10 minutes) was used, and this was introduced from the matrix resin supply port (1), and the fiber material Glass fiber roving made by Nippon Glass Fiber@ RER2
31-SMI 4 to 13m using a roving cutter
The fiber material was cut into lengths of m, and an amount to give a filling amount of 15% by weight to the polypropylene resin was quantitatively added through the fiber material supply port (2). The average fiber length and fiber filling amount of the obtained molded product were measured at the accumulator outlet and the end of the molded product. As shown in Table 1, a molded article with less fiber breakage and uniform fiber distribution was obtained. In addition, bending tests and impact tests were conducted on the obtained molded products, and it was confirmed that the mechanical properties were improved by fiber reinforcement.

Example 2 Except that a mixture of polypropylene resin (Sumitomo Noprene AX56B) and maleic acid-modified polypropylene resin at 10% was used as the matrix resin, and a glass fiber whose surface had been treated with vinyl silane was used as the matrix resin. A molding test was conducted under the same conditions as in Example 1. As shown in Table 1, the mechanical properties of the molded article obtained were excellent.

Example 3 A molding test was carried out under the same conditions as in Example 2 except that the cutting length when supplying the glass fiber was 25 mm. As shown in Table 1, the mechanical properties of the molded article obtained were excellent.

Comparative Example 1 As a matrix resin, a polypropylene resin filled with 30% glass fiber manufactured by Sumitomo Chemical @ (Sumitomo Noprene) was used.
Average fiber length of GHH43 glass fiber is 0. 7 mm) and glass fiber unfilled polypropylene resin (Sumitomo Noblen YIO1) manufactured by Sumitomo Chemical Co., Ltd. in a 1:1 ratio, the conditions were the same as in Example 1 except that glass fiber was not supplied from the fiber material supply port. A molding test was conducted. As shown in Table 1, the impact strength of the molded product obtained was insufficient.

Comparative Example 2 A molding test was conducted under the same conditions as in Example 1, except that glass fiber was introduced through the matrix resin supply port (1). As shown in Table 1, the impact strength of the molded product obtained was insufficient.

Comparative Example 3 A molding test was conducted under the same conditions as in Example 1, except that a plasticizing device having a full-fract type screw with a diameter of 50 mm and a screw length/screw diameter ratio of 10 was used. The molded product contained air bubbles, and the glass fibers were insufficiently defibrated and unevenly distributed.

<Effects of the Invention> As described above, by using the fiber-reinforced molding technology of the present invention, it is possible to reinforce with long fibers at the same time as molding, and it is possible to obtain a product that is uniformly reinforced to the edges of the product at a low cost. In addition, the appearance is significantly improved compared to the conventional long fiber reinforcement method, 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 drawings]

FIG. 1 shows a longitudinal sectional view of a plasticizing device for mixing matrix resin and fiber according to the present invention. (1) Matrix resin supply port (2) Fiber material supply port (3) Deaeration port (4) Screw (5) Cylinder (6) Nozzle Figure 2 shows a vertical cross section of the accumulator used in the embodiment of the present invention. It is a diagram. (7) Hydraulic cylinder (8) Molten resin cylinder (9) Hydraulic piston (10) Molten resin piston (11) Cylinder fixture (12) Oil inlet/outlet (13) Oil inlet/outlet (14) Molten resin supply port (15) Molten Resin Cylinder Nozzle FIG. 3 is a vertical sectional view of the plasticizing device-accumulator-mold used in the embodiment of the present invention. (16) Plasticizing and kneading device (17) Accumulator (18) Upper mold (19) Lower mold (20) Manifold part FIG. 4 is a perspective view of a molded product made by the method of the embodiment of the present invention. . 2nd

Claims (2)

[Claims] (1) A molten thermoplastic resin in which fibers with an average fiber length of 1 mm or more and 50 mm or less are dispersed as a reinforcing material is supplied into an unclosed mold, and the mold is closed and cooled under pressure to form a molded product. A method for producing a fiber-reinforced thermoplastic resin molded article with little deformation and excellent mechanical properties. (2) Molten thermoplastic resin is produced by a plasticizer with a screw length/screw diameter ratio of 15 or more, which has a fiber supply port in the center of the cylinder and a deaeration port on the nozzle side of the fiber supply port. A method for producing a fiber-reinforced thermoplastic resin molded article according to claim 1, which comprises supplying a fiber-reinforced thermoplastic resin molded article.