JPH05329875A - Method for molding fiber-reinforced resin - Google Patents

Abstract

PURPOSE:To obtain a fiber-reinforced resin molded object having a smooth design surface without fibers exposed on the surface by a method wherein a long-fiber mat made into a felt form is placed on a fixed mold for forming the design surface of a molded object, and after clamping, a resin is injected from the fixed mold. CONSTITUTION:A reinforcing material in use is a long-fiber mat 6 obtained by making long fibers relatively having a linearity into a felt form by a needle punching method or other similar method. A fixed mold 3 is provided with a resin injection port 7. A design surface of a molded object is formed on an inner surface 5 of the fixed mold 3. The mat 6 is placed on the inner surface 5 of the fixed mold 3. After a movable mold 4 is closed, a thermoplastic resin is injected. In this manner, the molded object can have a smooth and beautiful design surface and the reinforcing fibers dispersed in substantially a uniform state. The thickness of the mat 6 is preferably substantially the same as that of the molded object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a fiber-reinforced resin molded product which requires strength for automobile (structure) members, household appliances members, building materials and the like and has a smooth and beautiful design surface.

[0002]

2. Description of the Related Art As a molding method for a fiber reinforced resin molded product, a molding method using a metal mold has been developed, starting from hand lay-up, spray-up, etc., and gradually satisfying the requirements for appearance, dimensional accuracy and the like. As a molding method using the above-mentioned mold, a BMC (bulk molding compound) method in which a molding material (compound) in which reinforcing fibers are kneaded in advance in a resin is injection-molded, and a thermosetting resin is preliminarily applied to the reinforcing fibers. SMC (sheet molding compound) method that press-molds a sheet-shaped molding material impregnated with, and a stampable sheet molding method that heat-presses a sheet-shaped molding material by mixing reinforcing fibers into a thermoplastic resin. Being developed.

[0003]

However, each of the conventional molding methods described above has the following problems. That is, in the BMC method, the long fibers are easily cut when kneading the reinforcing long fibers into the resin, the reinforcing effect is limited, and the mixing of the fibers lowers the fluidity of the resin and deteriorates the moldability. At the same time, it is necessary to use an expensive material because the screws, cylinders, nozzles, etc. of the molding machine are easily worn. Further, since the reinforcing fibers are exposed on the surface and deteriorate the appearance, there is a problem that a coating treatment is required in the case of a molded article having a design surface.

Since the SMC method is press molding, there are restrictions on the shape of the molded product, and there are problems that the molding time is long and the recycling is difficult due to the thermosetting resin.
Also, stampable sheet molding is also press molding,
There are restrictions on the shape of the molded product and restrictions on the type of thermoplastic resin.

In both the SMC method and the stampable sheet method, the appearance of the surface of a molded product as it is is not always sufficient as a design surface, and various measures are required. An object of the present invention is to provide a molding method that solves the above problems and obtains a molded product that can be used as a design surface in appearance in particular.

[0006]

DISCLOSURE OF THE INVENTION The present invention comprises a needle punching method or a method similar to the above, which comprises a fixed die for forming a design surface of a molded article, which is made of long fibers having a relatively straight line as a reinforcing material. Place a long-fiber mat in the form of a felt, and clamp the movable mold together and then inject a resin from the fixed mold side to disperse the long fibers of the long-fiber mat in the resin. The present invention provides a method for molding a fiber-reinforced resin molded product, characterized by molding a fiber-reinforced resin molded product.

[0007]

In the molding method of the present invention, the resin extruded from the resin injection port of the injection molding machine first flows along the surface of the fixed mold forming the design surface provided with this injection port, After reaching the vicinity of the end of the mold, the long fiber mat is loosened by the pressure and flow of the resin, and is filled into the cavity while being almost uniformly dispersed. Therefore, it is possible to obtain a molded product in which long fibers do not appear on the surface of the design surface provided with the resin injection port, the surface has a smooth design, and the long fibers are almost uniformly dispersed.

[0008]

EXAMPLES The reinforcing long fibers used in the present invention are long fiber mats composed of relatively linear long fibers, and the long fibers are formed into a felt shape by a needle punching method or a method similar thereto. It is characterized by By using the reinforcing fibers of the above-mentioned form, the long fibers are sequentially unraveled during the resin molding process, and the localized uneven distribution of the reinforcing fibers that is observed when they are not unraveled is prevented, and the fibers are almost evenly dispersed throughout. The fiber-reinforced resin molded product thus obtained can be obtained.

As the reinforcing fibers, fibers having good heat resistance and tensile strength, which are generally used as advanced composite materials, are preferably used. For example, carbon fiber, graphite fiber, glass fiber, alumina fiber, silicon carbide fiber, boron fiber,
Inorganic and organic fibers such as Kevlar fibers and stainless steel fibers can be mentioned. These fibers, especially inorganic fibers, are preferably those whose surface is treated with a silane coupling agent or the like in order to improve the adhesion to the resin. As the reinforcing fiber, only one type may be used, or two or more different types may be used in combination.

If the long fibers have a very small fiber diameter, for example, glass long fibers thinner than Efiber (JIS standard, 6.35 to 7.62 μm), the fibers themselves retain relatively linearity. It tends to be difficult and easy to be entangled with each other and to be easily unraveled, and localized uneven distribution of the reinforcement tends to occur, which is not preferable. Although the preferable fiber diameter varies depending on the type of each fiber, for example, in the case of long glass fiber, G fi
ber (JIS standard, fiber diameter 8.89 to 10.02μ
m) or more, and generally has relatively linearity due to its fiber diameter.

Further, as the thickness of the reinforcing fiber mat,
It is preferably approximately the same as the thickness of the molded product. If the thickness is too thin, the dispersion of the fibers will be poor, and if it is too thick, it will not mix into the resin and only the fibers will squeeze out on the moving mold side and will not function as a reinforcing material.

The resin used in the present invention is not particularly limited as long as it is a thermoplastic resin. Examples of the thermoplastic resin include vinyl resins, styrene resins, olefin resins, acrylic resins and other general-purpose resins, nylon (polyamide resin), polycarbonate, polyacetal, polyester (PET, PBT, etc.), polyphenylene sulfide, polysulfone, and the like. Polyether sulfone,
Examples include engineering plastics such as polyether / ether / ketone, polyarylate, and polyimide.

An embodiment of the present invention will be specifically described below. The fiber-reinforced structural member 1 having a thickness of 3 mm shown in FIG. 3 was molded by using the molding method of the present invention. One surface of this structural member 1 has a design surface 2. For the molding, the injection mold shown in FIG. 2 was used. In FIG. 2, the fixed mold 3 is provided with a resin injection port 7, and the inner surface 5 is formed so as to be the design surface of the molded body.

In the molding procedure, first, the movable mold 4 is opened, and the long glass fiber mat 6 is placed on the inner surface 5 of the fixed mold 3.
This long glass fiber mat 6 has a relatively straight line G
A 3 mm thick mat formed by cutting the long glass fiber treated with a silane coupling agent into a length of 3 inches into a felt shape by a needle punch method (glass wool mat NA manufactured by Nippon Glass Fiber Industry Co., Ltd. -300-1000, nominal thickness 3 mm, unit weight 300 g / m < ² >) was used. As shown in FIG. 2, the size of the glass mat 6 is cut to have the same shape and size as the inner area of the fixed mold.

Next, the movable mold 4 is closed and the mold is clamped.
As shown in, the polyphenylene sulfide resin (PPS) is press-fitted from the resin injection port 7. The pressed resin 8 first flows along the inner surface 5 of the fixed mold while pressing the long glass fiber mat 6 against the inner surface 9 of the movable mold 4 to reach the vicinity of the cavity end 10, and then the glass length is increased by the pressure applied to the resin. The fiber mat is loosened, flows while being dispersed, and is filled in the cavity.

Thereafter, the molded product 1 is taken out after being cooled and solidified.
Has a smooth and beautiful design surface 2 with no fibers on the surface,
Moreover, the reinforcing glass fibers were highly uniformly reinforced by being dispersed almost uniformly.

Obtained fiber-reinforced PPS and unreinforced PP
The results of the physical property tests performed on the molded products of S resin are shown in Table 1 for comparison.

Further, the items listed in Table 2 were compared with respect to the fiber-reinforced resin molded articles produced by the conventional BMC method, SMC method and stampable sheet method.

[0019]

[Table 2]

[0020]

As is clear from Table 2, by carrying out the molding method of the present invention, it is possible to obtain a molded article which is more balanced than the conventional methods. Is characterized by being extremely good. Further, from the viewpoint of molding cycle, the molding cost is lower than that of SMC and stampable sheet, and the screw and cylinder of the molding machine are not worn against the BMC method, which is also advantageous in this respect.

[Brief description of drawings]

FIG. 1 is a sectional view showing a flow of resin in a mold in a molding step of a molding method of the present invention.

FIG. 2 is a cross-sectional view showing a state in which reinforcing fibers are placed in a mold.

FIG. 3 is a fiber-reinforced resin molding.

[Explanation of symbols]

 1 Fiber Reinforced Structural Member Molded by the Method of the Present Invention 2 Design Surface 3 Fixed Mold 4 Movable Mold 5 Design Inner Surface 6 Glass Long Fiber Mat 7 Resin Injection Port 8 Resin 9 Movable Mold Inner Surface 10 Cavity End

Claims (1)

[Claims] 1. A long die made of a long fiber having a relatively straight line as a reinforcing material on a fixed die for forming a design surface of a molded article, and formed into a felt shape by a needle punch system or a method similar thereto. The fiber mat is placed, the movable molds are aligned and clamped, and then the resin is injected and injected from the fixed mold side to disperse the long fibers of the long fiber mat in the resin to form a fiber-reinforced resin molded product. A method for molding a fiber-reinforced resin molded product, which comprises molding.