JPH0550433A - Preparation of fiber-reinforced composite material - Google Patents

Abstract

PURPOSE:To improve impregnating properties of a resin and to increase fiber content by specifying the structure of a reinforcing material. CONSTITUTION:At least two liq. raw materials 4 and 5 mixed in a mixing apparatus 2 are cast in a mold 3 wherein a reinforcing material is filled in advance and then reacted and cured to obtain a composite material. In this case, a reinforcing material layer 6 wherein 2 to 10 fiber layers each consisting of fiber bundles arranged by a strand density of 10-25 filaments/25mm are laminated in such a way that the fiber arranging direction in the adjoining fiber layer has an intersection angle of 10-90 deg. and they are kept at a knitting density of 2-10 filaments/25mm by using a knitting yarn, is used for performing injection molding.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The fiber-reinforced composite material produced by the method of the present invention has a high content of reinforcing fibers and is excellent in mechanical properties, and thus can be widely used in fields requiring specific strength. ..

[0002]

2. Description of the Related Art In recent years, in the fields of automobile members, housing materials for electronic devices, electrical insulating materials, etc., two or more kinds of liquid raw materials are mixed and then poured into a mold cavity to be injected into the mold cavity. 2. Description of the Related Art A reaction injection molding method (hereinafter referred to as RIM method) in which a molded body is obtained by reaction-curing at 2) is widely used. In addition, the structural reaction injection molding method (hereinafter referred to as the S-RIM method) in which a reinforcing fiber is filled in the cavity in advance and a composite material is obtained by injecting the above mixed liquid and curing by reaction is a relatively short cycle. Since a molded product having excellent mechanical properties can be obtained, it has been attracting attention and is being put into practical use as a new composite material molding method that replaces the hand lay-up method.

An outline of the S-RIM method is shown in FIG. In carrying out the method, the reactive liquid raw materials 4 and 5 contained in the tank 1 are discharged at the same time, and the mixed liquid obtained by collision and mixing in the mixing device 2 is injected into the mold 3 which is filled with the reinforcing material in advance. And heat-cured to obtain a composite material.

The mechanical properties of the composite material obtained by the above method depend mainly on the reinforcing material and the resin used, and in particular are governed by the content of reinforcing material. Therefore, it is important to increase the content of the reinforcing material. However, when the packing density of the reinforcing material in the mold is high, the flow resistance due to the reinforcing material when introducing the reactive resin raw material becomes large, and the movement of the reinforcing material in the mold and the resin to the reinforcing material are increased. Cause poor impregnation. Therefore, conventionally, the filling density of the reinforcing material is reduced or a reinforcing material having a small fiber density (random fiber mat or the like) is used to reduce the flow resistance at the time of injecting the resin raw material to solve the above problems. However, these solutions inevitably result in poor mechanical properties of the molded product.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the flow resistance is reduced by devising the array structure of the reinforcing material, rather than decreasing the flow resistance by the type of the reinforcing material. It is an object of the present invention to provide a method for producing a fiber-reinforced material having a high content of a reinforcing material and therefore having excellent mechanical properties by controlling the content to be low.

[0006]

The method for producing a fiber-reinforced material of the present invention, which has been able to solve the above-mentioned problems, is a method in which two or more kinds of liquid raw materials are mixed and injected into a mold filled with a reinforcing material in advance. Strand density: 10 to 2 in a structural reaction injection molding method in which a composite material is obtained by reaction curing
A fiber layer consisting of a group of fibers aligned at 5 fibers / 25 mm, and the fiber alignment direction in the adjacent fiber layers is 10 to 9
2 to 10 layers are laminated so as to form a crossing angle of 0 degree, and these are held at a knitting density of 2 to 10 yarns / 25 mm using knitting yarns and injected using a reinforcement layer. There is a point in molding.

[0007]

When the composite material is manufactured by the conventional S-RIM method, the content of the reinforcing material is 30 to 50% by weight at the maximum. On the other hand, in the present invention, the flow resistance due to the reinforcing material is suppressed to a low level by specifying the array structure of the reinforcing material, and the content of the reinforcing material is increased to 70% by weight or more. This will be described in more detail below.

As the multi-laminate used as the reinforcing material, a multi-laminate in which layers of aligned fiber groups are held by knitting is used. When a fiber having a fiber-fiber overlapping portion (crimp) such as a normal woven or knitted fabric is used, the fluidity of the resin is suppressed and the flow resistance is increased at that portion, but in the present invention, the overlapping portion Since no fibrous layer (non-crimp type non-woven fabric) is used, the flow of the resin is not obstructed at the overlapping portion, and the content of the reinforcing material can be increased. At this time, it is necessary to control the strand density to be 10 to 25 strands / 25 mm.
If the strand density is too low, the fiber content of the molded product will be low, and as a result its mechanical properties will be low, and if it is too high, the flow resistance of the resin will be large and the movement of the reinforcement and the resin to the reinforcement will be low. Cause poor impregnation. The total denier of the fiber varies depending on the material used, but in the case of glass fiber, for example, it is preferably 200 to 3000 d. The diameter is preferably 0.3 mm or less.

When laminating the fiber layers, the angle is changed. The change in the angle needs to be performed such that the adjacent fiber alignment directions of the adjacent layers intersect each other at 10 to 90 degrees. By laminating the intersecting angles at 10 to 90 degrees, the shape can be easily retained, and at the same time, the strength change in the horizontal direction of the obtained composite material can be suppressed to be low.

Next, each layer is integrally connected and held by knitting, and the density of the knitting yarn at that time needs to be controlled to 2 to 10 threads / 25 mm. If the density is too low, the fibers of the fiber layer are likely to be disturbed, and if it is too high, the flow resistance of the resin becomes large, causing problems such as not impregnating the reinforcing material with the resin.

The materials for the reinforcing material and knitting yarn used in the present invention are not particularly limited, and known reinforcing fibers such as glass fiber, carbon fiber, aramid fiber and mixtures thereof may be used in appropriate combination. Moreover, the shape thereof is not particularly limited, and either long fibers or short fibers can be used. The matrix material is also not particularly limited as long as it can be mixed and cured by mixing two or more kinds of liquid raw materials, and can be appropriately selected from epoxy resin, phenol resin, unsaturated polyester resin and the like.

Further, the non-overlapping type multi-layer glass fiber woven fabric of the present invention can be used not only alone but also in combination with various forms of reinforcing materials such as woven fabric, knitted fabric and non-woven fabric.

The present invention will be described in more detail with reference to the following examples, but the following examples do not limit the present invention.
All modifications and implementations are included in the technical scope of the present invention without departing from the spirit of the description below.

[0014]

【Example】

Examples 1 and 2, Comparative Examples 1 to 3 Example 1 Using a piston-cylinder type reaction injection molding machine (see FIG. 1), a non-overlapping multi-layered glass fiber fabric 6 [4 layers] was previously placed in the mold 3. (Each angle 0 ° / + 45 ° /
-45 ° / 90 °), basis weight: 2300 g / m ² , fiber strand density: 17/25 mm, knitting yarn density: 6
Book / 25 mm 2 sheets]. The epoxy resin 4 and the curing agent 5 in the tank 1 were metered and fed while being adjusted to have a ratio of 112: 30 (g), and after being collision-mixed by the mixing device section 2, at a speed of 142 g / sec. It was discharged into the mold. After that, molding was performed under conditions of a mold temperature of 130 ° C. and a molding time of 5 minutes.

Example 2 Using the same molding machine as in Example 1, a continuous fiber mat (weight per unit area: 300 g / m) was further added between two multi-layered fabrics having the same specifications.
² ) was sandwiched and molded under the same conditions.

Comparative Example 1 As a non-overlapping multi-layer glass fiber woven fabric, fiber strand density: 30/25 mm, knitting yarn density: 15 /
Molding was performed in the same manner as in Example 1 except that a 25 mm one was used.

Comparative Example 2 Instead of the non-overlapping type multi-layer glass fiber woven fabric, a plain woven glass fiber woven fabric (weight per unit area: 330 g / m ² , strand density: warp 1)
Molding was performed in the same manner as in Example 1 except that 8 sheets (6 lines / 25 mm, weft 14 lines / 25 mm) were laminated and used.

Comparative Example 3 The procedure of Example 1 was repeated, except that 6 continuous glass fiber mats (weight per unit area: 300 g / m ² ) were used instead of the non-overlapping multi-layer glass fiber woven fabric.

Table 1 shows the impregnation properties of the resin in the mold and the evaluation results of the mechanical properties of each molded product when formed as described above. The mechanical properties were evaluated as follows. * Bending strength: JIS K-7055 * Bending elastic modulus: JIS K-7055 * Izod impact strength: JIS K-7110

[0020]

[Table 1]

As shown in the table, Examples 1 and 2 had good resin impregnation properties, and composite materials having a higher fiber content than the conventional ones were obtained. Therefore, a material having excellent mechanical properties such as bending strength was obtained. On the other hand, Comparative Example 1 has a high strand density and knitting density, and Comparative Example 2 uses a plain woven fabric, so that the resin impregnation property is poor and impregnation failure is caused to fail to obtain a uniform composite material. Further, in Comparative Example 3, the resin impregnation property was good, but the mechanical properties were not so excellent because the fiber content was low.

[0022]

The present invention is configured as described above,
By limiting the structure of the reinforcing material, it has become possible to enhance the impregnation property of the resin and thus the fiber content. Therefore, the obtained composite material is excellent in mechanical properties such as bending strength.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an apparatus used for an S-RIM method.

[Explanation of symbols]

 1 Resin Raw Material Tank 2 Resin Mixing Device 3 Mold 4 Resin Raw Material 1 5 Resin Raw Material 2 6 Fiber Reinforcement Material

Claims (1)

[Claims] 1. A structure reaction injection molding method for obtaining a composite material by mixing and injecting two or more kinds of liquid raw materials into a mold preliminarily filled with a reinforcing material to obtain a composite material. Strand density: 10 2 to 10 such that a fiber layer composed of a group of fibers aligned at -25 fibers / 25 mm has a crossing angle of 10 to 90 degrees between adjacent fiber layers.
Layer them together and put them together using knitting thread 2
A method for producing a fiber-reinforced composite material, characterized in that the fiber-reinforced composite material is injection-molded by using a reinforcing material layer that is held at a knitting density of 10 fibers / 25 mm.