JP2726876B2 - Fiber reinforced thermosetting resin composition and method for producing cured fiber reinforced resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fiber-reinforced thermosetting resin composition and a method for producing a cured fiber-reinforced resin.

[0002]

2. Description of the Related Art It is known that a thermosetting resin composition reinforced with fibers contains rubber or a thermoplastic resin as an additive in order to increase the toughness of the cured product. When such a composition is heated and cured, the additive causes phase separation in the cured thermosetting resin that forms a matrix phase with the curing of the thermosetting resin, and as a result, A cured resin having a sea-island structure in which domains of the additive are dispersed in the cured thermosetting resin is formed. On the other hand, in order to produce such a cured fiber-reinforced resin, a method of impregnating a thermosetting resin composition into a reinforcing fiber to form a prepreg, using the prepreg as a molding material, and thermally curing the prepreg is used. Generally adopted. However, in such a method, when the composition containing the additive is melted to impregnate the fibers, the operation of impregnating the fibers with the melt is remarkable because the viscosity of the melt is extremely high. Difficult and impractical.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a fiber-reinforced thermosetting resin composition which gives a cured resin having high toughness, and a method for industrially advantageously producing a cured fiber-reinforced resin. The task is to provide.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, there is provided a fiber-reinforced thermosetting resin composition comprising a resin powder comprising a mixture of an aromatic polysulfone resin, an acrylonitrile-butadiene copolymer and a thermosetting resin, and fibers. Further, according to the present invention, there is provided a method for producing a cured fiber reinforced resin, wherein the fiber reinforced thermosetting resin composition is heated under pressure to melt and cure the resin powder.

As the thermosetting resin used in the present invention, various conventionally known resins which are liquid or solid at room temperature are used. As such, for example, epoxy resin, guanamine resin, diallyl phthalate resin,
Phenol resin, polyurethane, maleic acid resin, melamine resin, urea resin and the like can be mentioned. If necessary, a curing agent, a curing accelerator, a filler, a coloring agent, a flame retardant, and the like can be added to these resins. In the present invention, it is particularly preferable to use an epoxy resin. As the aromatic polysulfone resin, conventionally known ones, for example, Udel polysulphone, polyethersulfone and the like can be mentioned. Acrylonitrile
As the butadiene copolymer (hereinafter also referred to as NBR), those generally known as NBR can be used, and the acrylonitrile content is not particularly limited, but is preferably 30% by weight or more, preferably 35% by weight.
That is all.

In the present invention, the thermosetting resin, aromatic polysulfone resin and NBR are used as powder of a mixture in which they are uniformly mixed. In order to obtain this resin powder, the components are uniformly mixed in the presence of a solvent. In this case, the auxiliary additives are added and mixed as necessary. The solvent is removed from the obtained mixture to form a viscous liquid, which is poured into a mold, and the solvent is removed under vacuum to obtain a solid. In the solvent removing step, when the thermosetting resin is liquid at room temperature, the thermosetting resin forms a solid B-stage resin (prepolymer) at room temperature,
Heat. While this B-stage resin is solidified,
It still has thermosetting properties. Next, the solidified product is pulverized using a pulverizer to obtain a resin powder. This resin powder has thermosetting properties. The average particle size of the resin powder is not particularly limited, but is generally 300 μm or less,
Preferably 200 μm or less, more preferably 100 to 1
0 μm. When the mixing ratio of the thermosetting resin, the aromatic polysulfone resin and the NBR is shown, the thermosetting resin 10
The aromatic polysulfone resin is 2-2 to 0 parts by weight.
0 parts by weight, preferably 5 to 15 parts by weight, NBR is 2 to 20 parts by weight, preferably 5 to 15 parts by weight.

[0007] The fiber-reinforced thermosetting resin composition of the present invention comprises:
It can be obtained by mixing the resin powder and the fiber. Various conventionally known fibers are used as the fibers. Examples of such fibers include organic fibers such as aramid fibers, polyester fibers, nylon fibers, and polypropylene fibers, and inorganic fibers such as carbon fibers and glass fibers. The thickness of these fibers is usually 1 to 50 μm, preferably 5 to 20 μm, and the length is 0.05 to 0.5 mm for short fibers, preferably 0.1 to 0.2 mm, and long fibers. Is 1 to 10 cm, preferably 2 to 5 cm. The amount of the fiber is 1 to 50 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the resin powder.
20 parts by weight. The composition comprising the resin powder and the fibers can be filled into a mold and heated under pressure to form a cured resin. The heating temperature may be a temperature at which the resin powder melts and undergoes a curing reaction. The cured resin obtained in this manner is reinforced with fibers, has excellent mechanical strength, and has high toughness because it contains an aromatic polysulfone resin and NBR. Further, the resin cured body,
NBR forms a matrix phase, and a cured body composed of a thermosetting resin and an aromatic polysulfone resin is dispersed as domains (particles) in the matrix phase. Therefore, the cured product exhibits a large elongation to which a tensile stress is applied. This cured resin does not have defects such as microvoids.

[0008]

Next, the present invention will be described more specifically with reference to examples and comparative examples. The parts described below are parts by weight.

(Method for Preparing Resin Powder) Mixed solvent 1 comprising 9 parts of methylene chloride and 1 part of methanol
00 parts of polyethersulfone (PE) manufactured by ICI
S) (trade name: Victrex 50003P), 15 parts, and 10 parts of acrylonitrile-butadiene copolymer rubber (NBR) (manufactured by Nippon Synthetic Rubber Co., Ltd.) having an acrylonitrile content of 41% by weight, and further, bisphenol manufactured by Yuka Shell Epoxy Co., Ltd. A type epoxy resin (trade name: Epicoat 8)
28) 80 parts and 20,4,4'-diaminodiphenylsulfone were added to make a homogeneous solution. The solvent was evaporated and removed while stirring this liquid in an oil bath heated to 60 ° C., whereby a viscous and uniform liquid with a small amount of solvent remaining was obtained. This liquid was poured into a Teflon mold, which was heated to 140 ° C. and vacuum-dried. After completely removing the solvent, the liquid was cooled to obtain a solid. This solid was pulverized to prepare a resin powder having a particle size of 40 mesh or less. This resin powder is in a B-stage state and exhibits thermosetting properties.

Example 1 An average length of 0.2 g was added to 10 g of the resin powder prepared by the above method.
1 g of carbon short fiber [KCF-100] (trade name, manufactured by Kureha Chemical Co., Ltd.) having a fiber thickness of 14.5 μm and a uniform thickness of 50 kg / cm ² . It was kept under pressure at 180 ° C. for 3 hours. By this operation,
The resin powder was melt-cured to obtain a cured fiber-reinforced resin in which carbon fibers were well dispersed. A sample was cut out from the cured resin, the sample was cut, and the cut surface was polished. Then, the NBR phase was selectively stained with osmic acid, and ED
When analyzed by X [energy dispersive X-ray analyzer, manufactured by Philips, model: DX-4], NBR forms a matrix phase, and a cured body composed of epoxy resin and PES forms domains (particles). Dispersion in the matrix phase was observed.

Example 2 A cured carbon fiber reinforced resin was obtained in the same manner as in Example 1 except that 3 g of the carbon powder was added to 7 g of the resin powder. A sample was cut out from the cured resin, the sample was cut, the cut surface was polished, and EDX analysis was performed. As a result, it was observed that the carbon fibers tended to aggregate at the PES portion forming the domain.

Comparative Example 1 A mixed solvent of methylene chloride / methanol (mixing weight ratio = 9 /
1) 100 parts of polyether sulfone 15 g and NBR1
0 parts and 80 parts of epoxy resin (Epicoat 828) and 4,
To a homogenous solution in which 20 parts of 4'-diaminodiphenylsulfone was dissolved, 10 parts of the short carbon fiber shown in Example 1 was added, and the mixture was stirred well and the solvent was removed.
For 3 hours to produce a cured carbon fiber reinforced resin.
This cured resin contained 5.82% by volume of carbon fibers. Further, this one contained microvoids.

Comparative Example 2 A cured carbon fiber reinforced resin was produced in the same manner as in Comparative Example 1 except that the blending amount of short carbon fibers was changed to 15 parts. It contained 7.63% by volume of carbon fibers.
Further, this one contained microvoids.

As described above, the cured resin bodies of Comparative Examples 1 and 2 have microvoids, because it is difficult to completely remove the solvent in the solvent removing step. is there. According to the experiment, when the content of the fiber became 10 vol% or more, Comparative Examples 1 and 2
In this case, it has been confirmed that complete removal of the solvent becomes almost impossible, and microvoids are inevitably generated in the obtained cured resin.

Comparative Example 3 An attempt was made to produce a cured aramid fiber reinforced resin by blending 1.25 parts of aramid short fibers instead of carbon fibers. The fibers could not be kneaded smoothly.

Comparative Example 4 The above resin powder was melt-cured under the same conditions as in Example 1 to obtain a cured resin containing no fibers.

Next, the above Examples 1 and 2 and Comparative Examples 1 and 2
A three-point bending test piece was cut out from the cured fiber reinforced resin obtained in the above and the fracture toughness value was determined. The method of obtaining the fracture toughness differs depending on the difference in fracture behavior. The case where the load-transition curve shows linearity until immediately before fracture, and the fracture progresses at a burst at the maximum load is defined as brittle fracture, and the case where the load-transition curve shows nonlinearity and the fracture progresses slowly is defined as toughness fracture. I do. In the case of brittle fracture, G _1C (KJ / m 2) is calculated from K _1C (MN / m ² ) and energy value (U) using the following formulas (1) and (2) from the maximum load value (P) immediately before the fracture. ² ) Ask for.
In equations (1) and (2), S is the distance between fulcrums, a is the initial crack length, and B and W are the width and height of the test piece, respectively. Y and φ are correction terms. In the case of toughness fracture, a parameter J (KJ / m ² ) represented by the equation shown in (3) was obtained for the progress of the crack, plotted against the crack length, and extrapolated to 0 for the crack length. The value is defined as _J1C, and the energy required for crack initiation is defined as the fracture toughness value. As in Comparative Example 1, it is not preferable that the fracture behavior is changed from tough fracture to brittle fracture by filling with carbon fibers. In Examples 1 and 2, toughness fracture was exhibited, and the fracture toughness value was also improved.

[0018]

[Table 1]

[0019]

The cured product of the fiber reinforced resin according to the present invention does not contain microvoids and has excellent mechanical strength.
It has high toughness. Further, according to the method of the present invention, since a resin powder composed of a mixture of a thermosetting resin, an aromatic polysulfone resin and NBR formed in advance is used as a molding material, a cured fiber-reinforced resin is industrially advantageous. Can be manufactured.

[Brief description of the drawings]

FIG. 1 shows the temperature dependence of the storage elastic modulus of the cured resin obtained in Example 3, Example 4, and Comparative Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 The cured resin of Example 3 2 The cured resin of Example 4 3 The cured resin of Comparative Example 4

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Claims (2)

(57) [Claims] 1. A fiber-reinforced thermosetting resin composition comprising a resin powder and a fiber comprising a mixture of an aromatic polysulfone resin, an acrylonitrile-butadiene copolymer and a thermosetting resin. 2. A method for producing a cured fiber-reinforced resin, comprising heating the fiber-reinforced thermosetting resin composition according to claim 1 under pressure and melting and curing the resin powder.