JPH06246741A - Fiber reinforced resin continuum - Google Patents

Abstract

PURPOSE:To provide a fiber-reinforced resin continuous material in which an interlayer shearing strength of a molded form can be improved in a fiber- reinforced composite material. CONSTITUTION:A fiber-reinforced resin continuous material comprises reinforcing fiber impregnated.covered with resin in such a manner that 0.5vol.% or more of the entire fiber is discontinuous reinforcing fiber having 20mm or more of mean fiber length and discontinuous reinforcing fiber of an amount from 0.5vol.% to 5vol.% exists in a surface layer, and a molded form is obtained by molding the continuum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced resin continuous body in which some of the reinforcing fibers present in the surface layer are discontinuous fibers, and a molded product thereof.

[0002]

2. Description of the Related Art Various fiber-reinforced resin molding materials in which a thermosetting resin or a thermoplastic resin is impregnated between continuous fiber type reinforcing fibers are commercially available. For example, tape-shaped prepregs in which continuous reinforcing fibers are aligned in one direction and impregnated with matrix resin, prepregs in which continuous reinforcing fibers are woven and then impregnated with resin, and resin is impregnated between continuous reinforcing fibers. After that, a molding material and the like which is flattened is commercially available.

However, a molded article obtained by laminating these molding materials has a problem that the interlaminar strength is extremely low as compared with the strength of the reinforcing fiber in the reinforcing direction. For this reason, when the structure is used for a long period of time, peeling from the layers occurs, and problems such as reduced strength and reduced reliability occur, and the characteristics of fiber-reinforced composite materials with excellent mechanical properties are fully utilized. The current situation is that it has not been done.

[0004]

DISCLOSURE OF THE INVENTION In order to overcome the drawbacks of commercially available fiber-reinforced resin molding materials, that is, the molded article obtained by laminating molding materials has extremely low interlayer strength, As a result of a thorough study, a part of the reinforcing fibers present in the surface layer of the fiber-reinforced resin continuous material, which is a material for molding a fiber-reinforced resin, is made into discontinuous reinforcing fibers having an average fiber length of 20 mm or more. It has been found that the interlayer strength can be improved.

The present inventors have completed the present invention as a result of further studies based on such findings.

[0006]

That is, the present invention is a fiber-reinforced resin continuous body in which reinforcing fibers are substantially impregnated and covered with a resin, and 0.5% by volume or more of all the reinforcing fibers is contained. The discontinuous reinforcing fibers having an average fiber length of 20 mm or more and 0.5% by volume or more and 5% by volume or less of the total reinforcing fibers are present in the surface layer. The present invention provides a fiber-reinforced resin continuous body and a molded product obtained by molding the above fiber-reinforced resin continuous body.

In the present invention, the surface layer of the continuous fiber-reinforced resin means, when the cross section perpendicular to the axial direction of the continuous body is observed visually or by an optical microscope, 10% of the total thickness from the surface of the continuous body. Refers to the portion corresponding to the thickness.

In the present invention, examples of the reinforcing fiber which constitutes the fiber-reinforced resin continuous body include inorganic or organic fibers such as glass fiber, carbon fiber and aramid fiber. However, the reinforcing fiber is not particularly limited to these.

In the present invention, the resin constituting the fiber-reinforced resin continuous body includes a thermoplastic resin and a thermosetting resin, and the thermoplastic resin includes nylon 6 and nylon 6.
Polyamide resin such as 6, polyethylene terephthalate,
Polyester resin such as polybutylene terephthalate, polyolefin resin such as polypropylene and polyethylene,
Further, thermoplastic elastomers such as polycarbonate, polyetherimide, polyphenylene sulfide, polyether ketone, polyurethane elastomer, polyester elastomer and the like can be mentioned. Examples of the thermosetting resin include epoxy resin and unsaturated polyester resin.
However, the resin is not particularly limited to these.

Impregnation of resin into the reinforcing fiber in the present invention
As a coating method, a method which is generally used at present can be used. That is, any one of a resin bath impregnation method of passing reinforcing fibers in a resin bath, a film stacking method of stacking a matrix film on the reinforcing fibers, and a mixing fiber method of mixing the reinforcing fibers and the matrix fibers and then melting the matrix fibers. Although the method can be used, the mixed fiber method is preferable because it is easy to impregnate the reinforcing fibers with the resin and to arrange the reinforcing fibers in an array. The fact that the reinforcing fiber is substantially impregnated and covered with the resin means that the resin is arranged around the reinforcing fiber.

In the present invention, 0.5% by volume or more of all the reinforcing fibers constituting the fiber-reinforced resin continuous body has an average fiber length of 20 m.
It is necessary that the number of discontinuous fibers is m or more. This is because when the average fiber length of the reinforcing fibers is shorter than 20 mm, the mechanical properties when a high load is applied to the molded product produced from the fiber-reinforced resin continuous body are decreased.
When the discontinuous reinforcing fiber of 0 mm or more is less than 0.5% by volume, naturally the reinforcing fiber present in the surface layer is less than 0.5% by volume, and sufficient interlayer shear strength can be obtained when multilayer molding is performed. Because it is not possible. The average fiber length and volume content of the discontinuous reinforcing fibers are defined by the following equation.

[Equation 1] Lx: Length of each discontinuous reinforcing fiber (mm) n: Total number of discontinuous reinforcing fibers (pieces)

[0012]

[Equation 2] W1: Weight content of discontinuous reinforcing fiber (%) D1: Density of discontinuous reinforcing fiber (g / cm ³ ) W2: Weight content of entire reinforcing fiber (%) D2: Density of entire reinforcing fiber (g / Cm ³ )

In the present invention, the discontinuous reinforcing fibers having an average fiber length of 20 mm or more in an amount of 0.5% by volume or more and 5% by volume or less based on all the reinforcing fibers constituting the fiber-reinforced resin continuous body are the fiber-reinforced resin continuous bodies. It must exist on the surface. When the discontinuous reinforcing fibers present in the surface layer of the fiber-reinforced resin continuous body is less than 0.5% by volume, sufficient interlaminar shear strength cannot be obtained, and when it exceeds 5% by volume, the fiber-reinforced resin continuous body is obtained. This is because the handling property of is deteriorated. In addition, it is because the existence of the surface layer makes it possible to improve the interlayer strength.

In the present invention, the volume content of the reinforcing fibers constituting the fiber-reinforced resin continuous body is 1 of that of the fiber-reinforced resin continuous body.
It is preferably 0% by volume to 70% by volume, and more preferably 30% by volume to 60% by volume. This is because it is difficult to obtain desired mechanical properties when formed into a molded product unless the volume content is outside the range of 10% by volume to 70% by volume, and if the volume content is 30% by volume to 60% by volume, the desired mechanical properties can be easily obtained. This is because it can be obtained.

In the present invention, among the reinforcing fibers constituting the fiber-reinforced resin continuous body, the reinforcing fibers other than the above are preferably oriented substantially parallel to the longitudinal direction of the fiber-reinforced resin continuous body. This is to utilize the original characteristics of the fiber-reinforced composite material. Here, being oriented substantially parallel to the longitudinal direction means being aligned within ± 10 ° with respect to the axial direction of the fiber-reinforced resin continuous body.

As the method for molding the fiber-reinforced resin continuous body of the present invention to obtain a molded article, general methods such as filament winding, tape laying, pull-through and heat press can be used, but these are particularly preferable. It is not limited to.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
The interlaminar shear test was conducted according to ASTM D-2344. The volume% of discontinuous reinforcing fibers present in the surface layer of the fiber-reinforced resin continuous body in the present invention was measured and calculated using an optical microscope and an image processing device.

Example 1 Nylon 6 fibers and carbon fibers were aligned and spun and spun to blend the nylon 6 fibers and carbon fibers into a substantially non-twisted state, and the surface of the yarn was made of nylon 6 fibers. After winding and coating, a mixed yarn having a total yarn denier of 5800, a carbon fiber volume content of 50% by volume, and an average fiber length of 75 mm was obtained. This mixed filament yarn was continuously heated by an infrared heater to melt and impregnate nylon 6, and then a fiber reinforced resin continuous body of the present invention having a thickness of 0.1 mm and a width of 10 mm was passed through a shaping roll. The volume content of the discontinuous reinforcing fibers present in the surface layer of the fiber-reinforced resin continuous body was 1.5% by volume. Using the fiber-reinforced continuous body, heat press at a temperature of 250 ° C. and a pressure of 6 kg / cm ² to obtain a thickness of 2 m.
m, width 150 mm, length 250 mm, a unidirectional reinforcing material was molded and subjected to an interlaminar shear test. The obtained interlaminar shear strength was 9.5 kg / mm ² and had a high interlaminar shear strength.

Comparative Example 1 A continuous fiber-reinforced resin body having the same dimensions as in Example 1 was obtained by passing the carbon fiber consisting of continuous fibers through a hot-melted nylon 6 resin bath and impregnating the carbon fibers. Using the fiber-reinforced resin continuous body, a unidirectional reinforcing material was molded by the same method as in Example 1 and then an interlaminar shear test was performed. The obtained interlaminar shear strength was 5.7 kg / mm ² , which was lower than that of Example 1.

Comparative Examples 2 and 3 By the same method as in Example 1, except that the conditions were slightly changed.
The discontinuity present in the surface layer of the fiber-reinforced resin continuum due to
When the volume content of the reinforcing fiber is 0.1% by volume, 10% by volume
One similar to that of Example 1 was prepared by making a certain fiber-reinforced resin continuum.
Interlaminar shear test after producing a unidirectional fiber reinforcement by the method
Was done. As a result, the discontinuous reinforcing fibers present in the surface layer
When the volume of fiber is 0.1% by volume, the interlaminar shear strength is 6.8k.
g / mm ² In the case of 10% by volume, the original strengthening method
5.9kg / mm due to a decrease in reinforcement efficiency² Tona
The interlayer shear strength was lower than that of Example 1.

Comparative Example 4 In the same manner as in Example 1, except that the conditions were slightly changed so that the number average fiber length of the reinforcing fibers was 10 mm, a unidirectional reinforcing material was molded in the same manner as in Example 1, and then the interlaminar shear test was conducted. Was done. The interlaminar shear strength obtained as a result was 5.
It was 3 kg / mm ² , and the interlaminar shear strength was lower than that of Example 1.

[0022]

As is apparent from the above structure and explanation,
The fiber-reinforced resin continuous body of the present invention, as it is or a woven fabric,
After forming into a braid, it can be used for general molding methods such as filament winding, heat pressing, internal pressure molding, etc., and the structure produced by these methods has a greatly improved interlaminar shear strength in comparison with conventional products. The structure has excellent interlaminar shear strength, and the present invention has industrially high value.

Claims (2)

[Claims] 1. A fiber-reinforced resin continuous body in which reinforcing fibers are substantially impregnated and covered with a resin, wherein 0.5% by volume or more of all the reinforcing fibers are discontinuously reinforced with an average fiber length of 20 mm or more. Fiber and 0.5 for all the reinforcing fibers
The fiber-reinforced resin continuous body, wherein the discontinuous reinforcing fibers are present in a surface layer in an amount of 5% by volume or more and 5% by volume or less. 2. A molded product obtained by molding the fiber-reinforced resin continuous body according to claim 1.