JPH08290514A - Prepreg material - Google Patents

Abstract

PURPOSE: To obtain a fiber-reinforced prepreg with less generation of unevenness by being kept in standing after cutting and a low resin content by specifying the content of a matrix resin and the peeling resistance between the prepreg and a release sheet. CONSTITUTION: In a prepreg material in which a prepreg consisting of a reinforcing fiber and a matrix resin is sticked on a release sheet, the content of the matrix resin in the prepreg is 13-32wt.% and the peeling resistance between the prepreg and the release sheet is 10-250g/25mm. As the reinforcing fiber, glass fibers, aramide fibers and carbon fibers are preferable. In addition, as the matrix resin, epoxy resins are ordinarily used. In addition, as the release sheet,e.g. by adjusting appropriately the knid and the amt. of a silicone releasing agent, the peeling resistance of the prepreg can be made within the aimed range.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a prepreg material. More specifically, the present invention relates to a fiber-reinforced prepreg having a low resin content and excellent in winding workability.

[0002]

2. Description of the Related Art Fiber reinforced prepregs have come to be widely used for sports and leisure as an intermediate material for molded products such as golf shafts, fishing rods, badminton shafts and tennis racket frames. In recent years, fiber reinforced prepregs having a low resin content have been developed to further reduce the weight of golf shafts, fishing rods, and the like.

The fiber reinforced prepreg is usually formed into a sheet or roll by sticking a release sheet on one side for shape retention, storage or transportation. When the fiber-reinforced prepreg is molded into a cylindrical body, it is usually cut together with the release sheet, the fiber-reinforced prepreg is attached to the core, the release sheet is peeled off, and lapped to obtain the desired molded article. At this time, the fiber-reinforced prepreg cut until it is wound around the core is left for several hours, during which the fiber-reinforced prepreg with a low resin content is partially peeled off from the release sheet, and unevenness occurs on the surface of the prepreg. (Hereinafter, the irregularities on the surface of the prepreg are referred to as bumps). Since the fiber reinforced prepreg having a high resin content contains a large amount of resin, the adhesiveness between the release sheet and the fiber reinforced prepreg is good, and such a problem hardly occurs. When the fiber-reinforced prepreg in which such blistering occurs is wound around the core body, wrinkles are generated, and voids are generated, which causes problems such as strength reduction and poor quality of the obtained molded product.

In order to suppress the unevenness of the surface of the prepreg, Japanese Examined Patent Publication No. 60-37811 discloses a dimensional stability having an elongation of 0.5% or less with respect to the dimension in an absolutely dry state under a relative humidity of 60%. An invention using a good release sheet is disclosed.

However, in the fiber reinforced prepreg having a low resin content, it is the fact that the unevenness on the surface of the prepreg could not be sufficiently suppressed even by using such a technique. In addition, in order to prevent the occurrence of bubbling after cutting the prepreg, it is conceivable to shorten the leaving time after cutting or increase the ambient temperature for leaving, but if such a means is used, It is difficult to improve the production efficiency of products, and a large amount of capital investment is required.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a fiber reinforced prepreg having a low resin content which causes little flicker even if left after cutting. To do.

[0007]

The present invention has the following constitution in order to achieve the above object. That is, in a prepreg material in which a prepreg composed of reinforcing fibers and a matrix resin is adhered onto a release sheet, the content of the matrix resin in the prepreg is 13 to 32% by weight,
Peel resistance between prepreg and release sheet is 10 ~ 250g /
It is a prepreg material characterized by being 25 mm.

The present invention will be described in detail below.

The prepreg material of the present invention comprises a release sheet on which a prepreg composed of reinforcing fibers and a matrix resin is attached.

Examples of the reinforcing fiber used in the present invention include glass fiber, aramid fiber, carbon fiber and the like. However, when formed into a molded product, carbon fiber is used because it exhibits particularly excellent mechanical properties. preferable. As the carbon fibers, polyacrylonitrile-based or pitch-based carbon fibers can be used.

As the matrix resin used in the present invention, an epoxy resin is usually used. Examples of the epoxy resin include bisphenol A type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl amine type epoxy resin, alicyclic epoxy resin, urethane modified epoxy resin, and brominated bisphenol A type epoxy resin. Can be used. These epoxy resins can be used alone or in combination of two or more kinds, and further, they can be used in a liquid form to a solid form. Usually, a curing agent is often added to the epoxy resin before use.

The prepreg in the present invention has a resin content of 13 to 32% by weight, preferably 15 to 27% by weight, more preferably 17 to 25% by weight. If the resin content is less than 13% by weight, the amount of the resin is too small to obtain a prepreg of good quality and quality. If it exceeds 24% by weight, the prepreg surface will be rubbed without applying the present invention. It hardly happens.

In the present invention, the peeling resistance between the prepreg and the release sheet is 10 to 250 g / 25 mm, preferably 3
It is necessary to be 0 to 220 g / 25 mm. If the peeling resistance is less than 10 g / 25 mm, the surface of the prepreg is bumpy. On the other hand, if it exceeds 250g / 25mm,
It becomes difficult to peel off the prepreg from the release sheet, and the release sheet is ruptured, resulting in poor workability.

The peeling resistance between the prepreg and the release sheet is
It can be measured as follows.

A prepreg material is cut into a strip shape having a width of 25 mm and a length of 270 mm to obtain a test piece. The prepreg side of the test piece is adhered to the surface of a stainless steel jig through a double-sided tape as shown in FIG. Figure 2 shows a jig with test pieces attached.
Attached to the tensile tester as shown below, and the pulling speed is 50 mm /
The force required to separate the prepreg from the release sheet is measured as the amount. The measurement environment temperature is 23 ° C. and the humidity is 50%. The peel resistance is defined as the average value of the maximum load and the minimum load when such measurement is performed.

The release sheet used in the present invention can have the peeling resistance between the prepreg and the release sheet within the above range, for example, by appropriately adjusting the type and amount of the silicone-based release agent. The release sheet preferably has a degree of release of 110 to 400 g / 20 mm, preferably 150 to 340 g / 20.
mm, more preferably 180 to 300 g / 20 mm release sheet is used.

The degree of release of the release sheet is measured as follows.

A release sheet which is a sample is fixed on a smooth glass plate, and a permanent adhesive acrylic emulsion type pressure-sensitive adhesive is applied using an applicator (125 μ / wet). Immediately after coating, baking is performed at 100 ° C. for 120 seconds to dry. Immediately, another release sheet of the same type is placed on top of the sheet, and a rubber roller is used to bond the release sheet to the adhesive surface. After leaving it for about 30 minutes, it is cut into 2 cm width to make a test piece, and the upper release sheet is 18 at a pulling speed of 1 m / min.
The peeling force of the release sheet is measured by measuring the force of peeling with a 0 ° peel. The measurement length is 10 cm.

The release sheet used in the present invention has a dimensional change rate of 0.6% or less at room temperature (temperature 20 ° C.,
(Dimensional change when left for 20 hours in an environment with a humidity of 65%)
The use of the above-mentioned one has the effect of further preventing the occurrence of fluttering.

Further, as the reinforcing fiber in the present invention,
In addition to the ones in which the fiber bundles are aligned in one direction,
Although it may be in the form of a mat or the like, in order to reduce the resin content of the prepreg, it is preferable to use one in which the fiber bundles are aligned in one direction. In such a case,
The ratio of width to thickness of the fiber bundle is 5 to 200, preferably 8 to 1
It is preferably 50, and more preferably 10 to 120. If the ratio is less than 5, the fiber bundle may not spread easily in the step of prepreg formation, cracks may occur in the obtained prepreg, and it may be difficult for the matrix resin to impregnate the inside of the fiber bundle. On the other hand, it may be practically difficult to obtain a fiber bundle having a width-thickness ratio of more than 200. Here, the width D (mm) of the fiber bundle is obtained by actual measurement, and the thickness t (mm) of the fiber bundle is a value obtained by the following equation.

T = (f × d) / (D / d) where f is the number of filaments in the fiber bundle, and d (mm) is the diameter of the single fiber.

[0022]

EXAMPLES The present invention will be described in more detail below with reference to examples. The evaluation method of the prepreg in this example is as follows.

(1) Bumping on the surface of the prepreg The prepreg material in which the release sheet and the prepreg are stuck together is 1 m.
After being cut into a square of 1 m and left for 1 hour, the number of convex portions having a major axis of 3 mm or more on the prepreg surface is counted. (2) Wrapability A prepreg material having a release sheet and a prepreg attached thereto is cut in a fiber direction to a width of 100 mm and a length of 300 mm, the release sheet is peeled from the prepreg material, and the prepreg has a diameter of 15 mm.
Wrap it around a 500 mm long cylindrical core by hand. After wrapping, observe the prepreg for wrinkles or protrusions.

(Example 1) Epicoat 828 and Epicoat 1001 (bisphenol A glycidyl ether (epoxy equivalent 189): Yukakai Shell Epoxy Co., Ltd.
100 parts by weight and 5 parts by weight of dicyandiamide and 3
5 parts by weight of (3,4-dichlorophenyl) -1,1-dimethylurea was uniformly mixed to obtain a one-component cured epoxy resin composition. The one-component curing epoxy resin composition was used for the release degree 2
A resin film is prepared by coating a release paper of 10 g / 20 mm. A carbon fiber bundle having a width-to-thickness ratio of 20 is aligned in parallel with the longitudinal direction of the resin film with a uniform tension, and then the carbon fiber bundle is impregnated by passing it through a hot roller and simultaneously converted into a B stage. A prepreg material in which a carbon fiber reinforced prepreg having a width of 600 mm and a resin content of 19% by weight was adhered to a release paper was produced. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper was 92 g /
It was 25 mm. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material.

(Example 2) The resin content of the prepreg was set to 2
A prepreg material was produced in the same manner as in Example 1 except that the amount was 2% by weight. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper was 127 g / 25 mm. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material.

(Example 3) A prepreg material was produced in the same manner as in Example 1 except that a release paper having a release degree of 180 g / 20 mm was used. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper was 53 g / 25 mm. Table 1
The evaluation results are shown together with the fluffiness and wrapping property of the prepreg material.

Example 4 A prepreg material was produced in the same manner as in Example 1 except that release paper having a release degree of 250 g / 20 mm was used. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper was 206 g / 25 mm. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material.

(Example 5) The ratio of width and thickness of fiber bundle was 96.
A prepreg material was produced in the same manner as in Example 1 except that the carbon fiber bundle of was used. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper is 104 g / 25 mm
Met. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material.

Example 6 A prepreg material was produced in the same manner as in Example 1 except that a carbon fiber bundle having a fiber bundle width / thickness ratio of 4 was used. In the obtained prepreg material,
The peeling resistance between the prepreg and the release paper was 62 g / 25 mm. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material.

(Example 7) The ratio of width to thickness of fiber bundle was 23.
A prepreg material was produced in the same manner as in Example 1 except that the carbon fiber bundle of 0 was used. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper is 74 g / 25.
It was mm. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material.

(Comparative Example 1) The resin content of the prepreg was 1
A prepreg material was produced in the same manner as in Example 1 except that the amount was 2% by weight. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper was 8 g / 25 mm. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material. There were a lot of lumps and wrinkles occurred when wrapped around the core.

(Comparative Example 2) A prepreg material was produced in the same manner as in Example 1 except that a release paper having a release rate of 95 g / 20 mm was used. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper was 2 g / 25 mm. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material. There were a lot of lumps and wrinkles occurred when wrapped around the core.

(Comparative Example 3) A prepreg material was produced in the same manner as in Example 1 except that a release paper having a release rate of 370 g / 20 mm was used. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper was 262 g / 25 mm. Table 1
The evaluation results are shown together with the fluffiness and wrapping property of the prepreg material. Although no blistering occurred, it was difficult to peel off the release paper from the carbon fiber reinforced prepreg when winding it around the core, and it took a very long time to wind it.

(Comparative Example 4) The resin content of the prepreg was set to 3
A prepreg material was produced in the same manner as in Example 1 except that the amount was 4% by weight. In the obtained prepreg material, the peeling resistance between the prepreg and the release paper was 119 g / 25 mm. Table 1 shows the evaluation results together with the fluffiness and wrapping property of the prepreg material. Although no blistering occurred, the weight of the composite material member could not be reduced by using this prepreg because the amount of resin was too large.

[0035]

[Table 1]

[0036]

The prepreg material of the present invention has the peel resistance between the prepreg and the release sheet within the above range,
Despite the low resin content of the prepreg, the prepreg surface has little fluttering, thereby providing an effect that workability is excellent when, for example, the prepreg is wound around a core body.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a jig to which a prepreg material is attached, which is used when measuring the peel resistance between a prepreg and a release sheet in the present invention.

FIG. 2 is a schematic side view showing a state of a tensile test when measuring peel resistance between a prepreg and a release sheet in the present invention.

[Explanation of symbols]

 1: Double-sided adhesive tape 2: Prepreg 3: Release sheet 4: Stainless steel plate 5: Thread 6: Clip 7: Upper grip of tensile tester 8: Lower grip of tensile tester

Claims (5)

[Claims] 1. A prepreg material comprising a release sheet and a prepreg composed of reinforcing fibers and a matrix resin, wherein the content of the matrix resin in the prepreg is 1.
A prepreg material, which is 3 to 32% by weight and has a peel resistance between the prepreg and the release sheet of 10 to 250 g / 25 mm. 2. The prepreg material according to claim 1, wherein the matrix resin is an epoxy resin. 3. The release rate of the release sheet on the side where the prepreg is adhered is 110 to 400 g / 20 mm.
Described prepreg material. 4. The prepreg material according to claim 1, wherein the reinforcing fibers are fiber bundles which are aligned in one direction. 5. A prepreg material according to claim 4, wherein the ratio of width to thickness of the fiber bundle is in the range of 5 to 200.