JP2822465B2 - Method for producing fiber reinforced thermoplastic resin product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fiber-reinforced thermoplastic resin product used for industrial materials such as automobile exterior panel panels, automobile structural materials, battery parts and other automobile parts, and civil engineering and building materials. And a method for producing the same. More specifically, the present invention relates to a method for producing a fiber-reinforced thermoplastic resin product having a good surface appearance and excellent mechanical strength with little fiber orientation, twisting, deformation, and the like due to resin molding shrinkage.

<Prior Art> Conventionally, as a method of manufacturing a fiber-reinforced thermoplastic resin molded product, a typical method is to form short fiber-reinforced resin pellets by using a general molding method such as injection molding. In addition, using thermoplastic resin pellets reinforced with medium fiber length (fiber length 10 mm or less) fiber, which is almost the same length as the pellet cut length at the time of resin pellet production, fiber-reinforced thermoplastic resin molded products are injection molded. There is also a manufacturing method.

On the other hand, in recent years, a so-called stampable sheet technique of reheating a fiber-reinforced thermoplastic resin sheet to obtain a product by press molding has attracted attention. Stampable sheet technology is roughly classified into two types according to the fibers used for reinforcement. First, a single fiber of several millimeters to 100 millimeters in length and a thermoplastic resin powder are mixed in a wet or dry method, heated, roll-pressed to produce a stampable sheet, and after preheating this sheet, press molding To obtain a fiber-reinforced thermoplastic resin molded product. (For example, JP-A-57-28135). Another stampable sheet technology is extrusion lamination of a molten thermoplastic resin into a knitted long fiber mat, producing a stampable sheet via a roll press, preheating the sheet, and press molding to form a fiber reinforced thermoplastic. This is a method for producing a resin molded product.

<Problems to be Solved by the Invention> Conventional technologies have their own technical problems. The shortest fiber-reinforced resin pellet method, which is the most common method for producing fiber-reinforced thermoplastic resin molded products, has the drawback of improving mechanical strength, which is the primary purpose of fiber reinforcement, and is particularly ineffective in terms of impact strength. have. The reason for this is that the fiber is cut extremely short in the mixing and dispersing process of the fiber and the resin, that is, in the two plasticizing and kneading steps during granulation and injection molding. Furthermore, during the injection molding process, the fibers flow along with the molten resin in the narrow cavity clearance in the mold under remarkable shear, so that a strong fiber orientation remains in the fiber-reinforced thermoplastic resin molded product and the fiber-reinforced thermoplastic resin molded product Has a disadvantage that the fiber reinforced thermoplastic resin molded article is greatly deformed, and the dimensional stability in each direction of the fiber-reinforced thermoplastic resin molded article is poor. Next, in the case of the medium fiber length reinforced pellets, even if the fibers in the pellets are long, the fibers are cut short due to the plasticization step during injection molding and the remarkable shearing during the flow in the mold, and the impact strength is not improved. . The deformation of the fiber-reinforced thermoplastic resin molded product is large as in the case of the short fiber-reinforced pellet, and the dimensional stability is poor.

In medium and long fiber length fiber reinforced stampable sheets, the fibers remaining in the fiber reinforced thermoplastic resin molded product are
Since the length of the fiber used as the raw material is kept as it is, extremely high mechanical strength can be obtained. However, in the technology of single-fiber reinforced stampable sheet of medium fiber length,
The raw material of the thermoplastic resin must be a powder, and the product is expensive due to the cost of grinding. Furthermore, expensive and special equipment such as a paper machine, a roll press, and a preheater are required. The fiber orientation in the fiber-reinforced thermoplastic resin molded article is smaller than that in the case of the fiber-reinforced pellet because some fibers flow together with the molten resin at the time of molding, but the fiber orientation occurs and the molded article is easily deformed.

In the case of a long fiber-length stampable sheet, only the molten resin flows during molding, and the fibers are unlikely to flow, so that the outer periphery of the fiber-reinforced thermoplastic resin molded product has a resin-only portion and is not stable in strength. In addition, expensive and special equipment such as a fiber loom, an extruder, a roll press, and a preheater is required as in the case of the medium fiber stampable sheet.

<Means for Solving the Problems> As described above, the conventional technology has problems in mechanical properties, deformation, and the like, and cannot be said to be sufficient as an industrial technology. The inventors of the present application have intensively studied to develop a molding technique for overcoming these problems, but have finally developed a new method for producing an industrially excellent fiber-reinforced thermoplastic resin product described below. Was.

That is, the present invention, after the thermoplastic resin which gives a molded article flexural modulus less molding shrinkage 10/1000 has 25000kg / cm ² or more values as a matrix resin, which was melted plasticized, non-closure of the gold The inside of the mold is supplied from one side of the porous fibrous sheet placed in the mold, and through a gap of the porous fibrous sheet by pressing pressure, the molten thermoplastic resin is supplied to the opposite side of the porous fibrous sheet. This is a method for producing a fiber-reinforced thermoplastic resin product, characterized in that it is penetrated to the surface and molded.

In the present invention, a porous fibrous sheet is placed in a mold, a molten resin is supplied from one side of the sheet, and the entire surface of the fiber-reinforced thermoplastic resin product is uniformly reinforced in order to perform pressure molding. Because it is not cut and the molten resin flows from one surface of the fiber sheet to the other surface, no air bubbles remain inside the fiber reinforced thermoplastic resin product,
A fiber-reinforced thermoplastic resin product having an extremely high reinforcing effect can be obtained. Particularly when the molten resin is supplied in a state where the mold is opened, the pressure during molding is more evenly applied than in injection molding, so that the flow of the molten resin inside the fibrous sheet is more uniform over the entire surface of the molded product, which is preferable. .

In the case of this molding method in which the fibrous sheet is placed in a mold and the molten resin is supplied to one surface side of the mold, the layer of only the matrix resin on the side supplying the molten resin is relatively thick, while the layer on the opposite side is provided. Because the matrix resin layer becomes thinner,
That is, since the fibrous sheet is unevenly distributed, the fiber-reinforced thermoplastic resin product may be greatly deformed due to a difference in contraction force of the matrix resin. In order to prevent this deformation, the molding shrinkage is not more than 10/1000 and the flexural modulus is at least 25,000 kg / c.
It is preferable to use a matrix resin of m ² , more preferably a matrix resin having a molding shrinkage of 8.5 / 1000 or less and a flexural modulus of 30000 kg / cm ² .

The molding shrinkage here is 200 mm x 200 mm in size, using a 2.0 mm thick press mold, and preheated for 10 minutes or more at a temperature at which the thermoplastic resin used as the matrix resin is completely melted. Thereafter, a press-formed sample obtained by sufficiently cooling the thermoplastic resin in a cooling press is left in a room at 23 ° C. and 65% humidity for 24 hours, and then calculated by the following equation.

The flexural modulus is measured according to JIS K6758 using a sample prepared in the same manner as the sample for measuring the molding shrinkage.

Hereinafter, examples of the molding method in the present invention will be described with reference to the drawings. As an example, as shown in FIG. 1, a porous fibrous sheet is placed in an unclosed mold, and molten resin is supplied to one side of the fibrous sheet through a supply port in the mold, or the supply is completed. This is a method in which the mold is closed and the molding is performed. Also,
As shown in FIG. 2, a porous fibrous sheet in an unclosed mold is placed, molten resin is supplied onto the sheet from a supply port outside the mold, and then the mold is closed and pressurized and cooled. Through the process, a fiber-reinforced thermoplastic resin product can be obtained.

As the thermoplastic resin used in the present invention, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyamide, polycarbonate, ABS resin, polyacrylonitrile, resins such as polyethylene terephthalate, alone or as a mixture thereof, a polymer alloy is required. Depending on the usage, the filler may be filled with an inorganic filler such as talc, glass fiber, mica or wood flour. further,
These thermoplastic resins may contain additives such as heat stabilizers and UV inhibitors, coloring agents, and the like.

The material of the porous fibrous sheet used in the present invention is glass fiber, carbon fiber, inorganic fiber such as stainless steel fiber,
Also, a mixture of organic fibers such as polyamide fibers, polyester fibers, and aramid fibers and inorganic / organic fibers can be used. Particularly in the case of glass fiber, a high reinforcing effect can be obtained at low cost. Generally available fibers having a fiber diameter of 1 μm to 50 μm can be used. The porous fibrous sheet is 3 to 50 wt.
% Using a coagulant such as polyvinyl alcohol or epoxy resin.

The porous fibrous sheet used in the present invention may be used as a single sheet or as a plurality of sheets. When a plurality of porous fibrous sheets are used in a stack, the sheets may be a combination of the same or different materials, and the combination may be selected according to the application and required performance.

In particular, it is preferable to use a continuous or discontinuous single fiber as the porous fibrous sheet as the outermost layer, in order to obtain a product having a smooth surface appearance with less unevenness.

Further, in the present invention, in the molding process, the molten resin flows through the gaps of the porous fibrous sheet by pressure, but the flow resistance is large, and particularly in the case of inorganic fibers, heat is taken away by the fibers and the resin temperature decreases. Due to the large size, the fluidity is reduced, and the permeability of the resin to the surface of the fiber-reinforced thermoplastic resin product may be insufficient. It is also effective to preheat the fibrous sheet used to prevent this, for example, to 60 ° C. or higher before placing it between the molds.

<Examples> Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto. In addition, the test method of the molded article in an Example is as follows.

Bending test: Performed by a three-point support method according to JIS K6258. The test piece is 2mm cut from the box-shaped molded product shown in Fig. 3.
The test was performed at 23 ° C. using a 10 mm thick and 90 mm long.

Drop weight impact test: An Izod notch impact test was performed according to JIS K6258.

The shape of the test piece was 2 mm thick x 12.7 mm wide x 63.5 mm long and the test piece was cut from the box-shaped molded product shown in Fig. 3 and deformed at 23 ° C. The box-shaped molded product shown in Fig. 3 Was placed on a flat plate with its bottom face down, and four corners were individually pressed on the flat plate. The height of the remaining corners farthest from the flat plate was defined as the deformation of the molded article.

(Example 1) A molding test was performed using a vertical press molding machine having a clamping force of 200 tons and having a horizontally supplied injection section. The mold consists of two parts, an upper mold and a lower mold, and has a 2 mm diameter molten resin supply port inside the mold at the center of the lower mold.
mm, a box-shaped product (Fig. 3) having a product size of 200mm length x 200mm width x 40mm height was used.

As the porous fibrous sheet, a Cumulus sheet VHM5075 manufactured by Nippon Vilene Co., Ltd. made of glass fiber and made into a nonwoven fabric by a papermaking method was used. As the thermoplastic material, a material (Sumitomo Noblen GHH43, melt flow index 4.3 g / 10 minutes) in which 30% of glass fiber (fiber length 1 mm or less) was filled in polypropylene resin was used. After stacking two porous fibrous sheets in an unclosed mold, the molten resin is supplied from the supply port in the mold, and the mold is closed and pressurized and cooled at a pressure of 100 kg / cm ^2. Was. As shown in Table 1, a fiber-reinforced thermoplastic resin product having excellent mechanical strength and low deformation was obtained.

(Examples 2 to 3) Molding was performed under the same conditions as in Example 1 except that the matrix resin shown in Table 1 was used.
The appearance, deformability, etc. were evaluated. As shown in Table 1, a fiber-reinforced thermoplastic resin product having excellent mechanical strength and low deformation was obtained.

(Comparative Examples 1 and 2) Molding was performed under the same conditions as in Example 1 except that the matrix resin shown in Table 1 was used.
The appearance, deformability, and the like were evaluated in comparison with the fiber-reinforced thermoplastic resin molded product obtained in the examples. As shown in Table 1, the strength was poor or the deformation was large.

<Effect of the Invention> As described above, since the fiber-reinforced molding technology according to the present invention can be reinforced at the same time as molding, the fiber-reinforced thermoplastic resin product is extremely low in cost as compared with the conventional method, and particularly has excellent mechanical strength. It can be easily obtained, and various kinds of fibers can be combined according to the required performance of the product, and it is possible to provide fiber reinforced products in a wide range of application fields such as automobile parts, home electric parts, and building materials. Was.

[Brief description of the drawings]

1 and 2 are vertical sectional views of an apparatus showing a molding method of the present invention. DESCRIPTION OF SYMBOLS 1 ... Upper mold, 2 ... Lower mold 3 ... Porous fibrous sheet 4 ... Molten resin, 5 ... Molten resin supply port 6 ... Portable extruder Fig. 3 shows an embodiment of the present invention. FIG. 4 is a perspective view of a fiber-reinforced thermoplastic resin product produced by the method of FIG.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeyoshi Matsubara 2-10-1 Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Co., Ltd. (56) References JP-A-62-259819 (JP, A) JP-A Sho 60-36136 (JP, A) JP-B-60-16899 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 70/40-70/48

Claims (1)

(57) [Claims] 1. A molding shrinkage of not more than 10/1000 and a flexural modulus of 250
A thermoplastic resin that gives a molded product having a value of 00 kg / cm ² or more is used as a matrix resin, and after plasticizing and melting this, a mold is formed from one side of a porous fibrous sheet placed in an unclosed mold. Manufacturing of a fiber-reinforced thermoplastic resin product characterized in that the molten thermoplastic resin is permeated to the opposite surface of the porous fibrous sheet through the voids of the porous fibrous sheet by the pressing pressure Method.