JP2697107B2 - Method for producing fiber-reinforced thermoplastic resin molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to fiber reinforcement for industrial materials such as automobile exterior panels, automobile structural materials, automobile parts such as battery trays, and building materials such as access blowers. The present invention relates to a method for producing a thermoplastic resin molded product. More specifically, the present invention relates to a molding method for obtaining a fiber-reinforced molded article having a very small surface deformation due to fiber orientation and the like and having a good surface appearance by simultaneously strengthening and molding.

<Prior Art> Conventionally, several techniques have been known for obtaining a fiber-reinforced thermoplastic resin molded product, and are actually used as industrial techniques.
A typical method is a method of producing a fiber-reinforced molded product by a general molding method such as injection molding using short fiber-reinforced pellets. 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 fibers having a medium fiber length substantially equal to the cut length of the pellet at the time of pellet production.

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 the sheet is preheated and then pressed. This is a method of obtaining a fiber-reinforced molded product by heating. (For example, JP-A-57-28135). The other stampable sheet technology is a long fiber reinforced stampable sheet. In this method, a thermoplastic resin melted on a knitted long fiber mat is extrusion-laminated, a stampable sheet is produced through a roll press, the sheet is preheated, and a fiber-reinforced molded article is produced by press molding.

<Problems of the prior art> Each of the conventional technologies has its own technical and economical problems. The short fiber reinforced pellet method, which is most commonly used as a method for producing fiber reinforced molded products, is superior in formability, design compatibility, cost, etc. compared to other technologies, but it is the largest purpose of fiber reinforcement. Certain mechanical strength improvements, especially
There is a disadvantage that the effect is low in terms of impact strength.
The reason for this is that the fibers are severely cut during the mixing and dispersing processes of the fibers and the resin, that is, two plasticizing and kneading steps during granulation and molding. Furthermore, since the fibers flow in the mold together with the molten resin during the molding process, the fiber orientation remains in the molded product, and the molded product also has a disadvantage of being easily deformed. Further, in the case of fibers, particularly inorganic fibers, a significant problem from the viewpoint of cost is that the screws and cylinders of an extruder and an injection molding machine used for granulation, molding and the like are significantly worn.

On the other hand, the manufacturing process of a molded article using medium fiber length reinforced pellets requires a special extruder head, and the productivity is lower than that of short fiber reinforced pellets, resulting in a high cost product. Further, the deformation due to the fiber orientation in the molded product and the abrasion of the screw, cylinder and the like are the same as in the case of the short fiber pellet.

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

In the case of a long fiber stampable sheet, only the resin melted at the time of molding flows, and the fiber does not flow. Further, since the bundled fibers are used, the surface appearance tends to be rough. 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 is based on mechanical properties, deformation, appearance,
Each has its own problems, such as cost, and is not sufficient for industrial technology. The inventors of the present invention have intensively studied to develop a molding technique for overcoming these problems, but finally, a new production of an industrially excellent and low-cost fiber-reinforced thermoplastic resin molded article described below. A method has been developed. That is, the present invention relates to a method of stacking a plurality of porous fibrous sheets between upper and lower molds having a molten resin passageway in an upper or lower mold, closing the upper and lower molds, and supplying a molten resin supply port. After contacting the periphery of the hole provided in the porous fiber sheet on the side with the periphery of the molten resin supply port, when supplying the molten resin between the porous fiber sheet layers through the hole, the molten resin A method for producing a fiber-reinforced thermoplastic molded product, comprising opening a mold at the start of supply, closing the upper and lower molds before or simultaneously with the completion of the supply of the molten resin, and molding by pressing.

In the present invention, a plurality of porous fibrous sheets are placed, the molten resin is supplied between the fibrous sheet layers through the holes provided in the porous fibrous sheet on the supply port side, and the entire molded article is formed by pressure molding. Uniformly reinforced by fibers, fibers are not cut, and the molten resin penetrates into the sheet layer from between the sheet layers and flows toward the outermost sheet surface, so that no bubbles remain in the molded product, A molded article having a very high reinforcing effect can be obtained. Further, since the fibers do not flow together with the molten resin during the molding process, no fiber orientation is observed, and therefore, there is no warping or deformation of the molded product, and furthermore, the outermost layer of the porous fibrous sheet laminated on a plurality of sheets does not have a defect. By using a continuous single fiber sheet, it is possible to obtain a product having a smooth and beautiful resin surface with a high appearance required as an industrial product. In particular, by opening the mold at the start of the molten resin supply, closing the upper and lower molds before or at the same time as the completion of the supply of the molten resin, and press-molding, it is easy to mold even in complicated shaped molds. Molten resin can be supplied between the fibrous sheet layers, and molded articles of various shapes can be uniformly reinforced. The present invention is an epoch-making molding technique which can not be reinforced by fiber at the time of molding, which is not in the prior art.

Hereinafter, examples of the molding method in the present invention will be described with reference to the drawings.

A plurality of porous fibrous sheets are stacked and placed between the upper and lower molds having the molten resin passageway (7) in the lower mold (2) (FIG. 1 (A)). Is closed, and the periphery of the hole provided in the porous fibrous sheet (4) on the side of the molten resin supply port (6) is brought into contact with the periphery of the molten resin supply port (6) (first).
(B), when the molten resin (5) is supplied between the porous fibrous sheet layers through the holes, the mold is opened together with the supply of the molten resin (5) (FIG. 1 (C)), This is a method in which the upper and lower molds are closed and molded by applying pressure before or simultaneously with the completion of the supply of the molten resin (5) (FIG. 1 (D)).

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. On the other hand, the fiber length of the discontinuous single fiber sheet preferably used for the outermost layer is 100 mm or less, and more preferably 1 to 50 mm from the viewpoint of the production of the single fiber sheet and the obtained mechanical strength.

As the fiber used in the present invention, any of a single fiber and a bundled fiber obtained by bundling dozens to hundreds of single fibers with a bundling agent can be used. Further, the porous fibrous sheet in the present invention may be a sheet using a coagulant such as polyvinyl alcohol or epoxy resin in an amount of 3 to 50 wt% in order to maintain the sheet shape.

The thermoplastic resin used in the present invention is polyethylene,
Polypropylene, polystyrene, polyvinyl chloride, ABS
General thermoplastic resins such as resin, polyacrylonitrile, polyamide, polycarbonate, and polyethylene terephthalate, and mixtures thereof, and polymer alloys are used. Further, these thermoplastic resins may contain additives such as a heat stabilizer and an ultraviolet ray inhibitor, a coloring agent and an inorganic filler.

The plurality of fibrous sheets used for molding in the present invention may be a combination of the same type or a combination of different types, and the combination may be selected according to the application and required performance.

Further, in the present invention, in the molding process, the molten resin flows through the gaps of the porous fibrous sheet by pressure, but has a large flow resistance, and particularly in the case of inorganic fibers, the 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 molded 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 K7203.

Drop weight impact test: It was carried out using the apparatus shown in FIG.

50mmx50mm × 2mm cut out of glass fiber reinforced molded product
Place the barrel (12) on the thick test piece (14), drop the load (11) from above onto the barrel (12), and the minimum height of the load (11) when the test piece is broken Was used as the breaking height, and the obtained breaking energy was used as the impact strength.

Destruction energy (kg · cm) = Load (kg) x Destruction height (cm) Deformation of molded product: Place the box-shaped molded product shown in Fig. 2 on a flat plate with the bottom face down, and make four corners separately. When pressed down on the flat plate, the height of the remaining corner portion farthest from the flat plate was defined as the deformation of the molded product.

Surface appearance of molded article: The surface roughness of the molded article was measured using a surface roughness meter (manufactured by Toyo Seimitsu Co., Ltd., SURFCOM).

(Example 1) A molding test was performed using a vertical press molding machine having a 200-ton clamping force and having a horizontally supplied injection unit. The mold consists of two parts: a convex upper mold and a concave lower mold. The lower mold has a 2mm diameter direct supply port for molten resin in the mold. Dimension 200mm length X200mm
A box-shaped product (FIG. 2) having a width of 40 mm and a height was used.

 As a porous fibrous sheet, glass long fibers are bundled.
Sheets with overlapping rovings with no orientation
Vetrotex International (Vetrotex
 International) Unifilo sheet U
605-450). Two layers of this fibrous sheet
Diameter at the position of the molten resin supply port of the mold of the fibrous sheet on the side
A 10mm hole was created and placed on the lower mold after preheating to 60 ° C
(FIG. 1 (A)). Next, the upper and lower molds are closed, and the holes are
It is brought into contact with the molten resin supply port of the mold (FIG. 1 (B)),
Thermoplastic resin melted between layers of fibrous sheet through holes
(Sumitomo Chemical Industries, Ltd., Sumitomo Noblen AX568: Polyp
Propylene resin, melt flow index 65g / 10min)
The mold is opened at the speed of 15 mm / sec.
And move the mold at the position where the upper and lower mold gap is 10mm.
It stopped (FIG. 1 (C)). Simultaneously with the completion of molten resin supply
Start clamping and reduce the pressure applied during molding to 100 kg / cm^Twoage
Molding (FIG. 1 (D)). As shown in Table 1,
A molded article with extremely high mechanical strength was obtained.

(Examples 2 to 3) As shown in Table 1, as a porous fibrous sheet, a laminated sheet obtained by laminating two sheets of the same or different kinds was used for the upper layer and the lower layer, respectively. Example 1
A box-shaped molded product was obtained in the same manner as described above. A molded article excellent in mechanical strength and surface appearance was obtained.

(Comparative Examples 1-2) As thermoplastic resins, Sumitomo Noblen AX568 and glass fiber-filled polypropylene pellets, Sumitomo Noblen
GHH43 (Sumitomo Chemical Co., Ltd., glass fiber content 30wt
%) And no porous fibrous sheet was used, except that the molded article was molded under the same conditions as in Example 1 and the physical properties, appearance, deformability, etc. of the molded article were compared with the molded article obtained in the Example. did.

<Effect of the Invention> As described above, since the fiber-reinforced molding technique according to the present invention can be reinforced simultaneously with molding, a long-fiber-reinforced molded article can be easily obtained at a very low cost as compared with the conventional method, and Various types of fibers can be combined according to the required performance, and it has become possible to provide fiber-reinforced products for a wide range of application fields such as automotive parts, home electric parts, and building materials.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an apparatus showing a molding method of the present invention. Reference Signs List 1 upper mold 2 lower mold 3 porous fibrous sheet 4 porous fibrous sheet 5 molten resin 6, molten resin supply port 7 molten resin passage 2 FIG. 1 is a perspective view of a molded article produced by the method of the embodiment of the present invention. FIG. 3 is a vertical sectional view of the impact test apparatus used in the embodiment of the present invention. 11… Load, 12… Bank 13… Bank end R1 / 2 inch 14… Test piece 15… Test piece support

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Shigeyoshi Matsubara 2-10-1 Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Co., Ltd. (56) References JP-A-1-178417 (JP, A) JP-A Sho 62-275724 (JP, A)

Claims (1)

(57) [Claims] A plurality of porous fibrous sheets are stacked and placed between upper and lower molds having a molten resin passageway in an upper or lower mold, and the upper and lower molds are closed, and a molten resin supply port is provided. After contacting the periphery of the hole provided in the porous fiber sheet on the side with the periphery of the molten resin supply port, when supplying the molten resin between the porous fiber sheet layers through the hole, the molten resin A method for manufacturing a fiber-reinforced thermoplastic molded product, comprising opening a mold at the start of supply, closing the upper and lower molds before or simultaneously with the completion of supply of the molten resin, and pressing and molding.