JPH1086228A - Preparation of fiber-reinforced resin cured body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable industrial and advantageous preparation of a fiber-reinforced resin cured body having high tenacity. SOLUTION: Resin powder constituted of a mixture of aromatic polysulfone resin, an acrylonitrile-butadiene copolymer and thermosetting resin is molded in the shape of a sheet. Then, a fibrous sheet is laminated on this resin sheet, a laminated body thus obtained is heated under pressure and the resin sheet is melted and cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to 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]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for industrially advantageously producing a cured product of a fiber-reinforced resin having high toughness.

[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, a resin powder composed of a mixture of an aromatic polysulfone resin, an acrylonitrile-butadiene copolymer and a thermosetting resin is formed into a sheet shape, and a fibrous sheet is laminated on the resin sheet. Then, a method for producing a cured fiber reinforced resin characterized by heating the obtained laminate under pressure and melting and curing the resin sheet is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As the thermosetting resin used in the present invention, various known resins which are liquid or solid at ordinary temperature are used. Examples of such a resin include an epoxy resin, a guanamine resin, a diallyl phthalate resin, a phenol resin, a polyurethane, a maleic resin, a melamine resin, and a urea resin. These resins may contain, if necessary, a curing agent, a curing accelerator, a filler,
A coloring agent, a flame retardant and the like can be blended. In the present invention, it is particularly preferable to use an epoxy resin. As the aromatic polysulfone resin, conventionally known aromatic polysulfone resins, for example, Udel polysulphone
And polyethersulfone. Acrylonitrile-butadiene copolymer (hereinafter also referred to as NBR)
As the 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, and preferably 35% by weight or more.

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.

As the fibers, conventionally known various fibers are used, and in order to produce another resin cured body reinforced into fibers according to the present invention, first, the resin powder is formed into a sheet by using a pressure press. Mold into In this case, the temperature is lower than the curing temperature of the resin powder.
It is on the stage and shows thermosetting properties. In this case, the thickness of the resin sheet is 0.1 to 1 mm, preferably 0.2 to 0.5 mm. Next, a fiber sheet is laminated on the resin sheet. The fiber sheet in this case can be a nonwoven fabric, a woven fabric, a knitted fabric, a mat-like material, or the like. As the fiber, for example, aramid fiber, polyester fiber,
In addition to organic fibers such as nylon fiber and polypropylene fiber,
Examples include 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. The length of the fiber is usually 1
0 mm or more, 1 to 10 cm, preferably 2 to 5 c
m. The thickness of the fiber sheet is not particularly limited, but is usually 1 to 10 mm, preferably 2 to 5 mm. Although the number of laminations (the number of lamination surfaces) of the resin sheet and the fiber sheet is not particularly limited, it is usually 1 to 50, preferably 2 to 20. Further, it is preferable that the resin sheet and the fiber sheet are alternately stacked. The laminate of the resin sheet and the fiber sheet obtained as described above is placed in a press or a molding die and heated under pressure. The heating temperature in this case may be a temperature at which the resin sheet melts and cures.
The cured resin obtained as described above is reinforced by fibers and has good mechanical strength. The cured product has high toughness because it contains an aromatic polysulfone resin and NBR.
Further, in the cured product, a cured product composed of a thermosetting resin and an aromatic polysulfone resin forms a matrix phase, and NBR is dispersed as a domain in the matrix phase. This cured product has no defects such as microvoids, and the interface between the fiber and the matrix is also fixed.

[0008]

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

(Method for preparing resin powder) ICI was added to 100 parts of a mixed solvent consisting of 9 parts of methylene chloride and 1 part of methanol.
Polyethersulfone (PES) (trade name: Vi
trex 50003P) 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 a bisphenol A type epoxy resin (product of Yuka Shell Epoxy Co., Ltd.) Name: Epicoat 828) 80 parts and 4,4'-diaminodiphenylsulfone 20 parts 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 dried under vacuum.
After completely removing the solvent, the mixture 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.

Reference 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.

Reference Example 2 A cured carbon fiber reinforced resin was obtained in the same manner as in Reference Example 1, except that 3 g of 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.

Example 1 A resin powder prepared by the above-mentioned method was pressed and heated for 30 seconds under the conditions of a pressure of 1 MPa and a temperature of 140 ° C. for 30 seconds using a press machine, and was 0.2 mm thick and 220 g / weight. It has created a resin sheet of m ^2. Next, the resin sheet is laid on a carbon fiber sheet having the same shape as that of the resin sheet, and a carbon fiber sheet is further laid thereon. 180 ° C, pressure: 5MPa
Under the conditions described above for 3 hours to obtain a cured resin body reinforced with carbon fibers. The carbon fiber sheet has a fiber length of 5
A carbon fiber having a fiber size of 7.0 μm and a fiber thickness of 7.0 μm was formed into a mat having a weight of 40 g / m ² by using a separating and flying device. The cured carbon fiber reinforced resin obtained as described above contained 22.4% by volume of carbon fibers. In this method, a cured body composed of an epoxy resin and PES forms a matrix phase, and this matrix phase contains N
BR was dispersed as a domain. The fibers were uniformly dispersed in the matrix phase, and there were no defects such as microvoids, and the interface between the fibers and the matrix phase was also adhered.

Example 2 In Example 1, a fiber sheet having a fiber length of 5 cm was used.
Resin cured body reinforced with aramid fiber in the same manner except that aramid fiber having a fiber thickness of 11.9 μm was formed into a mat shape having a weight of 32 g / m ² by using a separating and flying device. I got This cured resin had a volume fraction of 9.1.
It contained 8% aramid fiber. In addition, as in the case of Example 1, the cured resin formed of an epoxy resin and PES forms a matrix phase of the cured resin,
The NBR was dispersed as domains in the matrix phase and was free of defects such as microvoids.

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 homogeneous solution in which 20 parts of 4'-diaminodiphenylsulfone was dissolved, 10 parts of the short carbon fiber shown in Reference 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 the short carbon fiber 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 fiber instead of carbon fiber. The fibers could not be kneaded smoothly.

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

Next, a three-point bending test piece was cut out from the cured fiber reinforced resin obtained in Reference Examples 1-2, Examples 1-2 and Comparative Examples 1-2 to determine the fracture toughness value. 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, use the following formulas (1) and (2) to calculate K _1C (MN
/ M ² ) and energy value (U) from G _1C (KJ / m 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) is obtained for the progress of the crack, and plotted against the crack length.
The value extrapolated to is defined as J _1C and the energy required for crack initiation is taken 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 Reference Examples 1 and 2, toughness fracture was exhibited, and the fracture toughness value was also improved. On the other hand, as shown in Examples 1 and 2, when filled with long fibers, it changes to brittle fracture,
Both K _1C and G _1C showed remarkable improvements.

[0020]

[Table 1]

Next, the storage modulus (Storage Module) of each of the cured fiber reinforced resin in Examples 1 and 2 and the cured resin of Comparative Example 4 containing no fiber was measured.
s) The temperature dependence of (Pa) is shown in FIG. The storage modulus in this case was determined as follows. (Storage modulus) Measured at a frequency of 5 Hz at a temperature rise of 2 ° C. per minute by a Seiko DMS110 dynamic viscoelasticity measuring apparatus. As can be seen from FIG. 1, the cured body of the fiber-reinforced resin of the present invention shows a high elastic modulus over a wide temperature range.

[0022]

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 1, Example 2, and Comparative Example 4.

[Description of Signs] 1 Cured resin of Example 1 2 Cured resin of Example 2 3 Cured resin of Comparative Example 4

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 63/00 C08L 63/00 71/10 71/10 75/00 75/00 81/06 81/06 // B29K 105: 08 B29C 67/14 W B29L 7:00 (72) Inventor Seid Hazard Rashid Hashimi Bhopal, India-462026, R.R.

Claims (1)

[Claims] A resin powder comprising a mixture of an aromatic polysulfone resin, an acrylonitrile-butadiene copolymer and a thermosetting resin is formed into a sheet, and a fibrous sheet is laminated on the resin sheet. A method for producing a cured fiber-reinforced resin, characterized in that the laminated body is heated under pressure and the resin sheet is melt-cured.