JPH10292254A - Wet nonwoven fabric for frp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject nonwoven fabric capable of providing a fiber- reinforced thermosetting resin composite material(FRP), excellent in impact resistance and suitable as a casing material for computers and electric machinery and apparatus by uniformly distributing bundled fibers composed of many bundled filaments. SOLUTION: This wet nonwoven fabric comprises fibers constituting the nonwoven fabric, in which >=20 wt.% of the fibers are bundled fibers prepared by bundling >=100 filaments. The nonwoven fabric is obtained by bonding interstices among the fibers with a binder having <=30 deg.C glass transition point, covering the fibers therewith and uniformly distributing the resultant bundled fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric for a fiber-reinforced thermosetting resin composite material (hereinafter abbreviated as FRP) having excellent impact resistance. The present invention relates to a suitable nonwoven fabric for FRP.

[0002]

2. Description of the Related Art FRP is manufactured by various molding methods such as injection molding and compression molding. Each manufacturing method has its own characteristics, and the molding method is used properly depending on the functions required conventionally. For example, when molding by compression molding method,
Since long fibers can be used, they are characterized by high bending strength and impact resistance. Therefore, it has been widely used for members requiring strength.

When the FRP is manufactured by a compression molding method, a woven or nonwoven fabric as a base material is impregnated with a resin, and is manufactured by heat compression molding using a mold or the like. When a woven fabric is used as the base material, the strength of the single fiber of the fiber can be maximized. Left a problem with gender.

On the other hand, FRP using a nonwoven fabric as a base material has been devised and put into practical use. Nonwoven fabrics include a wet method and a dry method, both of which are widely used. The feature of the production by the wet method is that the fiber is dispersed in a large amount of water to form a sheet, and therefore, is superior in terms of productivity and weight per unit area as compared with the dry method. Therefore, it is advantageous in terms of cost and uniformity of quality. However, in order to maintain the dispersibility in water, there is a tendency that only fibers having a fiber length of 50 mm or less can be used, and since there is little entanglement of the fibers, the impact strength tends to be poor.

Conventionally, various techniques have been devised to improve the impact resistance. Methods of adding highly elastic organic fibers, for example, vinylon, rayon, and aramid fibers, and methods of adding various whiskers have been devised. However, the addition of other fibers results in impairing the original physical properties of the main fiber, leaving a problem.

[0006]

Observation of the fracture surface after applying an impact to the FRP reveals that cracks are progressing mainly due to fracture or pulling out of the fiber itself. A conventional monofilament substrate is significantly cut or pulled out because the impact is received by a single fiber.

As another factor for reducing the impact strength, even when the fiber and the resin are firmly bonded, the impact strength is reduced because the stress cannot be absorbed at the interface. Accordingly, it is an object of the present invention to provide a wet nonwoven fabric for FRP capable of absorbing impact stress without changing the fiber material in order to improve the impact strength of the nonwoven fabric for FRP.

[0008]

In order to solve the above problems, the present invention employs the following constitution. That is, the present invention relates to a wet nonwoven fabric for FRP, characterized in that 20 wt% or more of the fibers constituting the nonwoven fabric are bundled fibers bundled with 100 or more filaments, and the bundled fibers are uniformly distributed. Things. Further, the present invention provides a binder for binding between the fibers of the nonwoven fabric and coating the binder with a glass transition point of 3%.
The present invention relates to a wet nonwoven fabric for FRP, wherein the temperature is 0 ° C. or lower.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. A feature of the present invention is that 20% by weight or more of the fibers constituting the nonwoven fabric are bundled with 100 or more fiber filaments. In order to reduce the impact per fiber, the filaments are bundled to reduce the propagation of cracks. It is to control. The method of bunching the fibers is arbitrary, but a method of controlling the type and amount of the sizing agent applied to the fiber surface, a method of using a polymer flocculant in combination, and the like can be used.

The phrase "bundled fibers are uniformly distributed" means that the bundled fibers are randomly distributed in the sheet. For example, only fibers in which 100 or more filaments are bundled are in the sheet. It means that it is not unevenly distributed.

When the number of fibers to be bundled is less than 100, impact cannot be sufficiently suppressed. 1
If the number exceeds 0000, local defects occur due to discontinuity of the network of bundled fibers. The fibers used in the nonwoven fabric of the present invention are not particularly limited, such as inorganic fibers and organic fibers. For example, any of inorganic fibers such as glass fiber, carbon fiber, and alumina fiber, and organic fibers such as rayon, aramid fiber, and polyester fiber can be used.
The fiber form is usually 3-50 mm in fiber length and 6-13 μm in fiber diameter in order to obtain a nonwoven fabric with a uniform basis weight by a wet papermaking method.
m fibers are used.

In the present invention, a binder is used for bonding the fibers or bonding the intersections of the fibers. The present invention binds these fibers together,
It is characterized in that the type of the binder to be bonded is defined as a glass transition point having a correlation with plasticity of 30 ° C. or less, and a stress absorbing layer is provided at the interface between the fiber and the resin. When the glass transition point is 30 ° C. or higher, the plasticity for relaxing the stress decreases, and the glass becomes brittle, so that the impact resistance decreases and the object of the present invention cannot be achieved.

The binder used in the present invention includes:
SBR, thermosetting acrylic resin, PVA, urethane resin, etc. can be exemplified, but if the glass transition point is 30 ° C. or less,
There is no particular limitation. The amount of the binder added is such that the resin impregnation after sheeting can be stably performed and the impregnating property is not impaired. Generally, 5% by weight or more based on the weight of the nonwoven fabric, preferably 10 to 3%.
It is necessary to add 0% by weight.

Further, in the present invention, if necessary, it is possible to add a coupling agent for bonding the fiber and the resin, or a filler or whisker for forming a micro-reinforced structure. These are not particularly exemplified, but commonly used coupling agents, fillers, whiskers and the like are added according to the application.

Finally, the nonwoven fabric for FRP of the present invention is impregnated with a resin such as a phenol resin, and is used for various applications as FRP.

[0016]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the content of the present invention is not limited to Examples.

Example 1 Glass fiber (UPG1) was added to an aqueous solution in which an alkyl betaine type surfactant (Discran B: manufactured by Daiwa Chemical Industry) was dissolved at a concentration of 50 mg / l as a dispersant.
/ 2ZA508 fiber diameter 9 μm fiber length 13 mm made by Unitika glass fiber) is dispersed at 0.5 g / l, and then cationic polymer flocculant (CLIFIX, CP-63)
3, Kurita Kogyo Co., Ltd.) was added in an amount of 0.5% by weight to the fiber to prepare a bundled fiber. The percentage of fibers in which 100 or more filaments were bundled was 40% by weight based on the total fiber weight.

Thereafter, the sheet is made into a sheet using a standard hand-making apparatus specified in TAPPI T 205, and then dried and dried.
g / m ² were obtained. Hereinafter, this sheet is referred to as “base paper”. This base paper was impregnated with 10 g / m ^{2 of} an acrylic emulsion (Borncoat ES-141, glass transition point of 13 ° C., manufactured by Dainippon Ink and Chemicals, Inc.) to prepare a nonwoven substrate nonwoven fabric. Next, phenol resin (Bellpearl S-
The mixture was impregnated with 65 parts of 890 (manufactured by Kanebo Co., Ltd., methanol) to produce a laminate at 170 ° C. for 60 minutes. This material was subjected to an Izod impact test in the edgewise direction according to the method specified in JIS K 7110. Table 1 shows the results.

<Comparative Example 1> In Example 1, a nonwoven fabric was prepared without adding a polymer coagulant, and a laminate was prepared in the same manner as in Example 1. This material is JIS K7
An Izod impact test was performed in the edgewise direction according to the method specified in No. 110. Table 1 shows the results.

<Example 2> In Example 1, an acrylic emulsion (Boncoat AN-180) was used as a binder.
(A glass transition temperature of 37 ° C. manufactured by Dainippon Ink and Chemicals) was impregnated to prepare a base nonwoven fabric, and a laminate was prepared in the same manner as in Example 1. This material was subjected to an Izod impact test in the edgewise direction according to the method specified in JIS K 7110. Table 1 shows the results.

Example 3 A carbon fiber (HT) containing a water-insoluble epoxy resin as a sizing agent in an aqueous solution in which an alkyl betaine type surfactant is dissolved at a concentration of 50 mg / l in a dispersant.
A-C6-E fiber diameter 7 μm, fiber length 6 mm, manufactured by Toho Rayon) were dispersed to form a sheet. All other conditions were the same as in Example 1. The ratio of fibers in which 100 or more filaments are bundled is 25% by weight based on the total fiber weight.
Met. Next, a laminate was prepared in the same manner as in Example 1,
The Izod impact test was performed in the edgewise direction according to the method specified in JIS K 7110. Table 1 shows the results.

Comparative Example 2 In Example 3, carbon fibers (HTA-C6-E, fiber diameter 7 μm, fiber length 6 mm,
After baking 800 ° C. for 1 minute to remove the sizing agent, a sheet was formed in the same manner as in Example 3. All other conditions were the same as in Example 1. The proportion of fibers in which 100 or more filaments were bundled was 10% by weight based on the weight of all fibers. Next, a laminate was prepared in the same manner as in Example 1, and an Izod impact test was performed in the edgewise direction by a method specified in JIS K7110. Table 1 shows the results.

[0023]

[Table 1]

[0024]

As described above, the present invention uses a binder in which 20% by weight or more of the main fiber is bundled with 100 or more filaments and the glass transition point is 30 ° C. or less in a wet nonwoven fabric for FRP. By doing so, FR with excellent impact resistance
P can be obtained.

Claims (2)

[Claims] 1. A wet nonwoven fabric for FRP, wherein at least 20% by weight of fibers constituting the nonwoven fabric are bundled fibers bundled with 100 or more filaments, and the bundled fibers are uniformly distributed. . 2. The wet nonwoven fabric for FRP according to claim 1, wherein the binder for binding and coating between the fibers has a glass transition point of 30 ° C. or lower.