JP3430569B2 - Heat resistant composite materials - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat resistant composite material comprising carbon fibers and a heat resistant resin matrix.

[0002]

2. Description of the Related Art A composite material having carbon fiber as a reinforcing material is lightweight and excellent in specific strength and elastic modulus. Therefore, it is suitable for structural materials for aerospace, golf shafts, tennis rackets, sports equipment such as fishing rods, etc. Widely used. Recently, the demand for aircraft applications is increasing. In particular, its use as a structural material for ultra-high speed aircraft has been studied.

However, when flying at a high speed exceeding Mach 1.5, the surface of the machine body becomes hot due to friction with the air. For example, in the case of Mach 2.4, the airframe surface temperature is calculated to be 160 to 260 ° C. although it varies depending on the part. As the matrix resin of the composite material that can withstand repeated use at such a high temperature, a heat resistant resin such as polyimide or polybismaleimide is used.
However, polyimide and polybismaleimide generally have low bonding strength with carbon fibers. Therefore, in order to exert its performance as a composite material, it is necessary to increase the binding force between the carbon fiber and the matrix resin. In order to develop the binding force between the carbon fiber and the matrix resin, so-called surface treatment is generally performed in which the surface of the carbon fiber is oxidized to introduce a functional group that reacts with the matrix resin.
As the method, gas phase oxidation treatment, chemical solution oxidation treatment, electrolytic oxidation treatment, and the like are used. Among them, the electrolytic oxidation treatment method is practical in terms of reaction stability, ease of operation, and the like. It has been adopted as a surface treatment method. However, most of the studies on the conventional surface treatment methods have been aimed at the epoxy resin matrix.

Japanese Patent Publication No. 63-6675 discloses that a monomer reaction mixture solution of polyimide is adhered to the surface of carbon fiber.
When this is heated and polymerized to form a polyimide film,
It has been shown that the adhesive strength with the heat resistant matrix resin is improved, but there is no means for improving the adhesive strength of the carbon fiber itself to the heat resistant matrix resin without interposing such a different polymer. Not listed.

[0005]

In order to develop the binding force between the carbon fiber and the matrix resin, it is essential to surface-treat the carbon fiber to introduce a functional group. The degree of surface treatment required when the matrix resin is an epoxy resin has been studied in the past and is well known, but in the case of a highly heat-resistant matrix resin,
The reality is that it is almost unknown.

In short, a technique for improving the adhesive force of the carbon fiber itself to a general epoxy resin, aside from the technique for improving the adhesive force of the carbon fiber itself to a highly heat-resistant matrix resin such as polyimide or polybismaleimide. It was the current situation that the above has not been studied so far.

An object of the present invention is to solve the above-mentioned problems of the prior art, that is, to provide a heat resistant composite material comprising carbon fiber and a heat resistant resin and having excellent composite physical properties.

[0008]

In order to solve the above problems, the present invention has any of the following configurations. That is, the tensile elastic modulus is 30000 kgf / mm ² or more and less than 50000 kgf / mm ² , the Raman spectrum of 1580 to 1600 cm ^{-1 and} the Raman band of 1350 to 1360 cm ^-1.
The thermal decomposition starting temperature after carbon fibers and curing ratio of the peak height is 0.90 to 1.10 of the Raman bands Ri Do from 250 ° C. or more resins, the resin is polyimide and / or port
Heat-resistant composite material is Libis maleimide or a tensile modulus 50000kgf / mm ² or more and less than 70000 kgf / mm ^2, the Raman bands and 1350～1360Cm ^-1 of 1580～1600Cm ^-1 Raman spectroscopy
The thermal decomposition starting temperature after carbon fibers and curing ratio of the peak height is 0.65-0.95 Raman bands Ri Do from 250 ° C. or more resins, the resin is polyimide and / or port
Is Libis maleimide refractory composite material or a tensile modulus 70000kgf / mm ² or more 96000 kgf / mm less than ^2, the peak height of the Raman bands of Raman bands and 1350～1360Cm ^-1 of 1580～1600Cm ^-1 Raman spectroscopy ratio Ri is Do from carbon fibers and the thermal decomposition initiation temperature of 250 ° C. or higher of the resin after curing is 0.45 to 0.70, the resin is polyimide and / or poly
It is a heat resistant composite material that is bismaleimide .

In the present invention, as the matrix resin, one having a thermal decomposition starting temperature of 250 ° C. or higher after curing is used. When the thermal decomposition starting temperature after curing is less than 250 ° C., the heat resistance is low and it cannot be used as the structural material for ultra-high speed aircraft which is the object of the present invention. As such a heat resistant resin, polyimide and / or polybismaleimide are preferable.

The carbon fiber used in the present invention can be obtained, for example, by subjecting the raw material carbon fiber to an anode and subjecting it to an electrolytic oxidation surface treatment in a specific electrolyte aqueous solution under specific conditions, as will be described later.

As the electrolyte at this time, an inorganic acidic electrolyte, an inorganic alkaline electrolyte, or an organic alkaline electrolyte can be used. As the inorganic acidic electrolyte, there are inorganic oxo acids such as sulfuric acid and nitric acid.
Examples include ammonium carbonate and ammonium bicarbonate, as well as ammonium hydroxide, ammonium chloride, ammonium sulfate and ammonium thiosulfate. Examples of the inorganic alkaline electrolyte include strong alkalis such as sodium hydroxide and potassium hydroxide. As an organic alkaline electrolyte,
Examples thereof include quaternary amines such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and β-hydroxyethyltrimethylammonium hydroxide, and amines such as hydrazine, triethylamine and guanidine.

When electrolytically oxidized surface treatment is performed using these electrolytes, the conductivity of the aqueous solution is preferably 10 mS / cm or more, more preferably 20 mS / cm or more. Conductivity is 10 mS
If it is lower than / cm, the operating voltage must be set to a high voltage exceeding 25 V in order to introduce the necessary oxygen-containing groups, which poses a safety problem.

Therefore, more preferable electrolytes are sulfuric acid, nitric acid, ammonium carbonate which is an ammonium salt of carbonic acid, ammonium bicarbonate, which is a strong acid having high conductivity in an aqueous solution, and sodium hydroxide, potassium hydroxide and tetramethyl which are strong alkalis. Examples thereof include ammonium hydroxide, tetraethylammonium hydroxide and β-hydroxyethyltrimethylammonium hydroxide. Among these, it has been found that in the case of an alkaline electrolyte, a stronger surface treatment can improve the physical properties of the composite.
Therefore, in the case of the alkaline electrolyte, it is preferable to carry out the surface treatment with a higher amount of electricity than in the case of the electrolyte other than the alkali.

The higher the firing temperature, that is, the higher the tensile elastic modulus of carbon fiber, the more the graphite structure develops and the more difficult it becomes to be oxidized. Therefore, in order to oxidize this and introduce a functional group necessary for strengthening the binding force with the matrix resin onto the surface of the fiber, it is necessary to enhance the degree of electrolytic surface treatment.

Therefore, in the present invention, in order to further strengthen the binding force between the carbon fiber and the matrix resin, while suppressing the decrease in the tensile strength of the composite in the 0 ° direction, an appropriate amount is selected according to the tensile elastic modulus. It uses carbon fiber with a functional group introduced, and the amount of this functional group is 15 in Raman spectroscopy.
It can be expressed by the ratio of the peak heights of the Raman band of 80 to 1600 cm ^{-1 and} the Raman band of 1350 to 1360 cm ^-1 .

That is, the tensile elastic modulus is 30,000 to 50,000 kg.
In the case of f / mm ² carbon fiber, Raman spectroscopy 1580 to 1600
The ratio of the peak heights of the Raman bands of Raman bands and 1350～1360Cm ^-1 of cm ^-1 it is an 0.90 to 1.10. When the ratio of the peak heights is less than 0.90, the degree of destruction of the carbon fiber structure is insufficient, functional groups are not sufficiently introduced, and the bond strength with the heat resistant resin becomes insufficient. On the other hand, if the peak height ratio exceeds 1.10, if some yarns break in the initial stage of the composite, the fracture propagates to the adjacent yarns via the resin that is firmly bonded to this yarn, so the overall tensile strength is increased. Will decrease. In the case of carbon fiber having a tensile elastic modulus of 50000 to 70000 kgf / mm ² , the ratio of the peak heights of the Raman band of 1580 to 1600 cm ^-1 and the Raman band of 1350 to 1360 cm ^-1 of Raman spectroscopy is 0.65 to 0.95. To do. When the ratio of the peak heights is less than 0.65, the degree of destruction of the carbon fiber structure is insufficient, the functional groups are not sufficiently introduced, and the bond strength with the heat resistant resin becomes insufficient. On the other hand, the peak height ratio is 0.95.
If it exceeds, if a part of the yarn breaks in the initial stage in the composite, the fracture propagates to the adjacent yarn through the resin strongly bonded to the yarn, and the tensile strength decreases as a whole.

In the case of carbon fiber having a tensile elastic modulus of 70000 to 96000 kgf / mm ² , the ratio of the peak heights of the Raman band of 1580 to 1600 cm ^-1 and the peak of Raman band of 1350 to 1360 cm ^-1 in Raman spectroscopy is 0.45. It should be ~ 0.70. When the ratio of the peak heights is less than 0.45, the degree of destruction of the carbon fiber structure is insufficient, the functional groups are not sufficiently introduced, and the bond strength with the heat resistant resin becomes insufficient. On the other hand, if the peak height ratio exceeds 0.70, if some yarns break in the initial stage of the composite, the fracture propagates to the adjacent yarns via the resin that is firmly bonded to this yarn, so the tensile strength as a whole increases. Will decrease.

The preferable conditions of the electrolytic surface treatment for producing the carbon fiber into which an appropriate amount of functional group is introduced according to the tensile elastic modulus are shown below.

[0019] That is, if the tensile modulus of 30000 kgf / mm ² or more 55000kgf / mm ² less than the carbon fibers, if the tensile modulus of the carbon fiber and ^{x (10 3 kgf / mm 2} ), carbon fiber 1
10 (0.058x-0.190) to 10 (0.057x-0.021) per gram
It is preferable to use the amount of electrolysis of Coulomb. On the other hand, in the case of carbon fibers having a tensile elastic modulus of 55000 kgf / mm ² or more and 95000 kgf / mm ² or less, it is preferable that the coulomb is 1000 coulomb or more and 1300 coulomb or less per gram of carbon fiber.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples.

The tests of fineness, specific gravity and resin-impregnated strand were carried out according to JIS R 7601-1986.

The Raman spectroscopic analysis was carried out by using a 5145 Å argon ion laser as a light source and measuring 1580 to 1600 by macro Raman measurement with a measurement arrangement of 90 °.
Raman bands and the ratio of the height of the peak of the Raman bands of 1350～1360Cm ^-1 of cm ^-1 (hereinafter, the peak height ratio of the Raman spectroscopy) was determined.

Here, the tensile strength expression rate (%) is defined as [value of unidirectional tensile strength in terms of fiber volume content of 60.0% (kgf / mm
² )] / [tensile strength of resin-impregnated strand of carbon fiber before surface treatment (kgf / mm ² ) × 0.6] × 100.

(Example 1) High-strength medium-elasticity carbon fiber "Torayca" T800H-12K (number of filaments: 12000) manufactured by Toray Industries, Inc., which is not surface-treated or sized.
Book, fineness: 445 g / 1000 m, specific gravity: 1.81 g / cm ³ , resin-impregnated strand tensile strength: 566 kgf / mm ² , resin-impregnated strand tensile elastic modulus: 30100 kgf / mm ² , Raman spectral peak height ratio: 0. 79) was surface-treated in an aqueous sulfuric acid solution having a concentration of 0.07 N while running at a speed of 2.4 m / min with an electric quantity of 40 coulomb per gram of carbon fiber. At this time, the conductivity of the aqueous sulfuric acid solution was 18.0 to 18.8 mS / cm, and the operating voltage was 9.2 to 9.8V. While running at the same speed, wash in countercurrent water for 7.0 minutes and then 1.5 at 150 ° C.
It was dried for a minute and wound on a bobbin. This resin had a resin-impregnated strand tensile strength of 556 kgf / mm ² , a resin-impregnated strand tensile elastic modulus of 30100 kgf / mm ^2, and a Raman spectroscopic peak height ratio of 0.90. Since the peak height ratio of Raman spectroscopy is large, it can be seen that the surface treatment has made the carbon fiber surface layer amorphous. Next, using this yarn, a unidirectional prepreg having the following constitution was manufactured. The prepreg comprises the above carbon fiber and the following matrix resin composition, and the weight fraction of the matrix resin is 32%.
And

[Matrix Resin Composition] N, N-Bismaleimidediaminodiphenylmethane (manufactured by Ciba-Geigy 5292A) 215 parts by weight N, N-Bismaleimide tolylenediamine (BMI-TDA manufactured by Mitsui Toatsu Co., Ltd.) 113 parts by weight o , O-diallyl bisphenol A (5292B manufactured by Ciba-Geigy) 246 parts by weight Thermoplastic polyimide (5218 manufactured by Ciba-Geigy) 64 parts by weight The resin composition was molded by an ordinary vacuum bag autoclave molding method at a heating rate of 1.7. After raising the temperature at ℃ / min and reaching 191 ℃, it is 6kgf / cm ² for 4 hours at 191 ℃.
Was carried out under pressure. Then, the temperature was decreased to room temperature at a temperature decrease rate of 2.5 ° C./min. Next, the post-cure was heated in a hot air circulation dryer at a temperature rising rate of 4.0 ° C./min, reached 232 ° C., and then carried out at 232 ° C. for 16 hours under normal pressure. About this resin cured product, the thermal decomposition start temperature and the 5% weight loss temperature measured at a temperature rising rate of 10 ° C./min in a helium atmosphere of 50 CC / min using a Shimadzu TG-30 thermobalance were measured. 328 ° C and 367 ° C. The thermal decomposition initiation temperature of a general epoxy resin composition is 200 ° C. to 2
It can be seen that the heat resistance of the matrix resin composition used in the present invention is much higher than that at 30 ° C.

The weight fraction of resin in the obtained prepreg was 36%. 190 g of carbon fiber per unit area
/ M ² . Next, this prepreg was laminated in 6 layers in one direction, and the molding was carried out by a usual vacuum bag autoclave molding method at a temperature rising rate of 1.7 ° C./minute to reach 191 ° C. and then at 191 ° C. for 4 hours. It was carried out under a pressure of 6 kgf / cm ² . Then, the temperature was decreased to room temperature at a temperature decrease rate of 2.5 ° C./min. Next, the temperature of the post cure was raised in the hot air circulation dryer at a temperature rising rate of 4.0 ° C./min, and after reaching 232 ° C., 232 ° C.
At atmospheric pressure for 16 hours. The thickness of the forming plate is 1.1
It was 4 mm. The glass transition temperature of the molded plate measured using a 30-inch DSC apparatus manufactured by METTLER CORPORATION in a nitrogen atmosphere of 50 CC / min at a temperature rising rate of 40 ° C./min was 302 ° C.
Met. This molded plate has a length of 235 mm in the fiber direction and a width of 1
Cut it to 2.7 mm, leaving 127 mm in the center in the length direction,
A unidirectional tensile test piece was prepared by sticking a 1.0 mm thick glass fiber and a hardened plate tab made of epoxy resin to each 54 mm. The fiber volume content of this test piece was 58.7%. This was subjected to a tensile test with an Instron model 4208 at a tensile speed of 1.25 mm / min. At this time, the tensile strength is 60.0% of the fiber volume content, and the converted value is 318.
It was kgf / m ² . The tensile strength development rate was 93.6%, which indicates what percentage of the tensile strength of the carbon fiber before the surface treatment was expressed as the unidirectional tensile strength of the composite.

Next, using the same prepreg, one direction 2
Four layers were laminated and subjected to autoclave molding under the same conditions as in the case of the molded plate for unidirectional tensile test piece. The thickness of the molded plate was 4.50 mm. A test piece for measuring compression interlayer shear strength was cut out from this molded plate according to Boeing Material Spec BMS8-276, and the compression interlayer shear strength was measured by an Instron model 4208 at a strain rate of 1.27 mm / min. It was 1 kgf / mm ² .

Next, using the same prepreg, 24 layers of pseudo isotropic structure (+ 45 ° / 0 ° / -45 ° / 90 °) 3S were laminated, and the same as the case of the molded plate for unidirectional tensile test piece. Autoclave molding was performed under the conditions. 101.6 mm x from molded plate
A 152.4 mm test piece was cut out and subjected to falling weight impact energy of 1500 inch-pounds / inch according to Boeing Material Spec BMS8-276. Then, the compressive strength after impact was measured by an Instron model 1128 at a strain rate of 1.27 mm / min and was 18.4 kgf / mm ² .

Table 1 shows the results of these evaluations.

[0030]

[Table 1] (Example 2) With respect to the carbon fibers used in Example 1 which were not surface-treated or sized, ammonium carbonate having an aqueous solution concentration of 0.6 N was used as an electrolyte, and the amount of electrolytic electricity per gram of carbon fibers was 80. Resin-impregnated strands of carbon fiber surface treated with Coulomb Tensile strength 551 kgf / m
m ² , the resin-impregnated strand tensile elastic modulus was 30,200 kgf / mm ² , and the Raman spectroscopic peak height ratio was 1.08. Since the ratio of the peak heights of Raman spectroscopy is larger than that in the case of Example 1, it can be seen that the surface treatment further amorphizes the carbon fiber surface layer portion. For this carbon fiber, a prepreg was made in the same manner as in Example 1, and the molded composite was measured, and the fiber volume content was 6
The unidirectional tensile strength converted to 0% is 314 kgf / mm ² , the tensile strength development rate is 92.5%, and the compressive interlaminar shear strength is 11.5.
kgf / mm ^2, compression strength after impact was 18.3kgf / mm ^2.
The results of these evaluations are also shown in Table 1.

(Embodiment 3) With respect to carbon fibers not subjected to the same surface treatment and sizing as in Embodiment 1, ammonium bicarbonate having an aqueous solution concentration of 0.4 N was used as an electrolyte, and electrolytic electricity per gram of carbon fibers was used. Amount of resin-impregnated carbon fiber surface-treated with 80 coulomb Tensile strength 55
5 kgf / mm ² , resin-impregnated strand tensile modulus 30100 kgf /
The peak height ratio in mm ² and Raman spectroscopy was 1.01.
Since the ratio of the peak heights of Raman spectroscopy is larger than that in the case of Example 1, it can be seen that the surface treatment further amorphizes the carbon fiber surface layer portion. For this carbon fiber, a prepreg was made in the same manner as in Example 1, and the unidirectional tensile strength converted to a fiber volume content of 60% measured on a molded composite was 315 kgf / mm.
² , tensile strength development rate 92.8%, compression interlaminar shear strength 1
1.7kgf / mm ² and compressive strength after impact is 18.1kgf / mm ²
Met. The results of these evaluations are also shown in Table 1.

Example 4 With respect to the carbon fibers used in Example 1 which were not surface-treated or sized, tetraethylammonium hydroxide having an aqueous solution concentration of 0.1 N was used as an electrolyte per 1 g of carbon fibers. The resin-impregnated strand has a tensile strength of 538 kgf / mm ² , a tensile modulus of resin-impregnated strand of 30100 kgf / mm ² and a peak height ratio of Raman spectrum of 1.15. there were. Since the ratio of the peak heights of Raman spectroscopy is further increased, it can be seen that the surface treatment further amorphizes the surface portion of the carbon fiber. For this carbon fiber, a prepreg was prepared in the same manner as in Example 1 and the unidirectional tensile strength measured for the molded composite was 317 kgf / mm ² , the tensile strength development rate was 93.3%, and the compressive interlaminar shear strength was 11.8 kgf. / mm ² , and the compressive strength after impact was 18.9 kgf / mm ² . The results of these evaluations are also shown in Table 1.

(Example 5) High-strength and high-modulus carbon fiber "Torayca" M35J-12K (number of filaments: 12000, manufactured by Toray Industries, Inc., which is not surface-treated or sized.
Fineness: 450 g / 1000 m, Specific gravity: 1.75 g / cm ³ , Resin-impregnated strand tensile strength: 487 kgf / mm ² , Resin-impregnated strand tensile elastic modulus: 35200 kgf / mm ² , Raman spectral peak height ratio: 0 .72), a resin-impregnated strand having a tensile strength of 459 kgf / mm ^{2 of} carbon fiber surface-treated with sulfuric acid having an aqueous solution concentration of 0.07 N as an electrolyte and having an electrolytic electricity of 160 coulomb per gram of carbon fiber, The resin-impregnated strand had a tensile elastic modulus of 35100 kgf / mm ² and a Raman spectral peak height ratio of 1.11. For this carbon fiber, a prepreg was prepared in the same manner as in Example 1 and the molded composite was measured, and the fiber volume content was 60.
% Unidirectional tensile strength 261 kgf / mm ² , tensile strength development rate 89.3%, compressive interlaminar shear strength 10.0 kgf / mm
² and the compressive strength after impact were 17.9 kgf / mm ² . The results of these evaluations are also shown in Table 1.

(Example 6) Medium-strength and high-modulus carbon fiber "Torayca" M40-12K manufactured by Toray Industries, Inc., which is not surface-treated or sized, (filament number: 12000, fineness: 728 g / 1000 m, specific gravity) : 1.81 g / cm ³ , resin-impregnated strand tensile strength: 286 kgf / mm ² , resin-impregnated strand tensile elastic modulus: 40200 kgf / mm ² , Raman spectral peak height ratio:
0.64), the concentration of the aqueous solution as an electrolyte is 0.1
Resin-impregnated strands have a tensile strength of 266 kgf / mm ² and a resin-impregnated strand tensile elastic modulus of carbon fibers surface-treated with 320 coulombs of electrolytic electricity per gram of carbon fibers using the specified β-hydroxyethyltrimethylammonium hydroxide. The peak height ratio of Raman spectroscopy was 40200 kgf / mm ² and 1.00. About this carbon fiber, Example 1
The unidirectional tensile strength 153 kgf / mm ² converted to a fiber volume content of 60% and the tensile strength development rate 89.
2%, compression interlaminar shear strength was 8.6 kgf / mm ² , and post-impact compression strength was 15.1 kgf / mm ² . The results of these evaluations are also shown in Table 1.

(Example 7) High-strength and high-modulus carbon fiber "Torayca" M46J-12K (number of filaments: 12000, manufactured by Toray Industries, Inc., which is not surface-treated or sized)
Fineness: 445 g / 1000 m, specific gravity: 1.84 g / cm ³ , resin-impregnated strand tensile strength: 441 kgf / mm ² , resin-impregnated strand tensile elastic modulus: 44500 kgf / mm ² , Raman spectral peak height ratio:
0.60), the concentration of the aqueous solution as an electrolyte is 0.1
Using the specified tetraethylammonium hydroxide,
Electric strength of electricity per gram of carbon fiber 500 Coulomb surface-treated carbon fiber resin impregnated strands Tensile strength 402
kgf / mm ² , resin-impregnated strand tensile modulus 44400 kgf / mm
^2. The peak height ratio of Raman spectroscopy was 0.97. For this carbon fiber, a prepreg was made in the same manner as in Example 1 and the molded composite was measured, and the unidirectional tensile strength converted to a fiber volume content of 60% was 228 kg.
f / mm ² , tensile strength development rate was 86.2%, compression interlaminar shear strength was 7.5 kgf / mm ² , and post-impact compression strength was 14.5 kgf / mm ² . The results of these evaluations are also shown in Table 1.

(Example 8) High-strength, high-modulus carbon fiber "Torayca" M50J-6K (number of filaments: 6000, fineness: 216g / 1000m, specific gravity) manufactured by Toray Industries, Inc., which is not surface-treated or sized. : 1.88 g / cm ³ , Resin-impregnated strand tensile strength: 411 kgf / mm ² , Resin-impregnated strand tensile modulus: 48500 kgf / mm ² , Raman spectral peak height ratio:
0.53), the concentration of the aqueous solution as an electrolyte is 0.1
Using the specified tetraethylammonium hydroxide,
The amount of electrolysis per gram of carbon fiber 850 Coulomb surface-treated resin-impregnated strands of carbon fiber surface-strength 368
kgf / mm ² , resin-impregnated strand tensile modulus 48600 kgf / mm
^2. The peak height ratio of Raman spectroscopy was 0.98. With respect to this carbon fiber, a prepreg was prepared in the same manner as in Example 1 and the molded composite was measured, and the unidirectional tensile strength was 211 kg converted into a fiber volume content of 60%.
f / mm ^2, the tensile strength development rate 85.6%, compressive interlayer shear strength 7.0 kgf / mm ^2, compression strength after impact was 12.3kgf / mm ^2. The results of these evaluations are also shown in Table 1.

(Example 9) High-strength and high-modulus carbon fiber "Torayca" M55J-6K manufactured by Toray Industries, Inc., which has not been surface-treated or sized, (number of filaments: 6000, fineness: 218 g / 1000 m, specific gravity) : 1.91 g / cm ³ , Resin-impregnated strand tensile strength: 410 kgf / mm ² , Resin-impregnated strand tensile modulus: 55000 kgf / mm ² , Raman spectrum peak height ratio:
0.31), the concentration of the aqueous solution as an electrolyte is 0.1.
Using the specified tetraethylammonium hydroxide,
Electricity of electricity per gram of carbon fiber 1200 Coulomb surface-treated resin impregnated strand of carbon fiber Tensile strength 37
2 kgf / mm ² , resin-impregnated strand tensile modulus 55 100 kgf /
The peak height ratio in mm ² and Raman spectroscopy was 0.82.
For this carbon fiber, a prepreg was prepared in the same manner as in Example 1, and the molded composite was measured.
Unidirectional tensile strength 214 converted to fiber volume content 60%
kgf / mm ^2, the tensile strength expressed 84.9% compressive interlayer shear strength 6.4kgf / mm ^2, compression strength after impact is 11.0kgf / mm ²
Met. The results of these evaluations are also shown in Table 1.

(Example 10) Pitch fiber having 500 filaments was melt-spun by a known method using synthetic pitch obtained by polycondensation of naphthalene with hydrogen fluoride and boron trifluoride as a catalyst. Got After making the pitch fiber infusible in the air, the yarn is mixed and the number of filaments is 200
0 yarns, draw ratio 1.01 in nitrogen gas atmosphere
Then, the temperature was raised up to 3000 ° C. and graphitized to obtain graphitized yarn. The fineness of this yarn measured according to JIS R7601-1986 was 280 g / 1000 m, and the specific gravity was 2.
21 g / cm ³ , resin-impregnated strand tensile strength is 405 kgf /
mm ² , resin-impregnated strand tensile modulus of elasticity is 95300 kgf /
It was mm ² . The ratio of the peak heights of Raman spectroscopy is
It was 0.21. For the fiber, tetraethylammonium hydroxide having an aqueous solution concentration of 0.1 N was used as an electrolyte, and the amount of electrolysis was 18 per gram of carbon fiber.
00 resin-impregnated strand tensile strength of 349kgf / mm ² of the carbon fiber surface-treated with Coulomb, resin-impregnated strand tensile modulus of 95200 kgf / mm ^2, the peak height ratio of the Raman spectroscopy 0.
It was 56. For this carbon fiber, a prepreg was prepared in the same manner as in Example 1 and the molded composite was measured, and the unidirectional tensile strength converted to a fiber volume content of 60% was 199 kgf / mm ² , and the tensile strength expression rate was 81. 9%,
Compressive interlaminar shear strength 5.7 kgf / mm ² , compressive strength after impact is 1
It was 0.8 kgf / mm ² . The results of these evaluations are also shown in Table 1.

Comparative Example 1 Resin-impregnated strands of carbon fiber surface-treated under the same conditions as in Example 1 except that the amount of electrolysis was 6 coulombs Tensile strength 563 kg
f / mm ² , resin-impregnated strand tensile elastic modulus 30200 kgf / mm ²
The peak height ratio of Raman spectroscopy was 0.85. For this carbon fiber, a prepreg was made in the same manner as in Example 1, and the molded composite was measured, and the unidirectional tensile strength was 325 kg converted to a fiber volume content of 60%.
f / mm ^2, the tensile strength development rate 95.7%, compressive interlayer shear strength 8.2 kgf / mm ^2, compression strength after impact was 13.2kgf / mm ^2. The results of these evaluations are also shown in Table 1. Compared with the composite physical properties of Examples 1, 2, 3 and 4, the unidirectional tensile strength is rather high, and therefore the tensile strength development rate is high, but the compressive interlaminar shear strength, which is a measure of the binding force between the fiber and the matrix resin, It can be seen that the post-impact compression strength, which is an index of impact resistance, is low.

Comparative Example 2 Tensile strength of resin-impregnated strands of carbon fiber surface-treated in the same manner as in Example 1 except that the amount of electrolysis was 150 coulombs.
3 kgf / mm ² , resin-impregnated strand tensile elastic modulus 30 100 kgf /
The peak height ratio of Raman spectroscopy was 1.22 in mm ² .
For this carbon fiber, a prepreg was prepared in the same manner as in Example 1, and the molded composite was measured.
Unidirectional tensile strength 243 converted to fiber volume content 60%
kgf / mm ^2, the tensile strength development rate 71.6%, compressive interlayer shear strength 12.0 kgf / mm ^2, compression strength after impact is 18.5kgf / mm
^{Was 2} . The results of these evaluations are also shown in Table 1. Compared with the composite physical properties of Examples 1, 2, 3 and 4, the compression interlaminar shear strength was slightly improved, but it was found that the unidirectional tensile strength and the tensile strength development rate were extremely lowered. It

(Comparative Example 3) In Example 7, a resin-impregnated strand of carbon fiber was surface-treated under the same conditions except that the electrolyte was a 0.07 normal concentration aqueous solution of sulfuric acid and the electrolysis amount was 80 coulomb. The strength was 432 kgf / mm ² , the resin-impregnated strand tensile elastic modulus was 44500 kgf / mm ² , and the Raman spectroscopic peak height ratio was 0.69. With respect to this carbon fiber, a prepreg was prepared in the same manner as in Example 1, and the molded composite was measured, and the unidirectional tensile strength converted to a fiber volume content of 60% was 243 kgf / mm ² , and the tensile strength expression rate was 91. 8%, compression interlaminar shear strength 4.6 kgf /
mm ² , and the compressive strength after impact was 10.7 kgf / mm ² . The results of these evaluations are also shown in Table 1. Compared with the composite physical properties of Example 7, as in the case of Comparative Example 1, the unidirectional tensile strength is rather high, and therefore the tensile strength expression rate is high,
It can be seen that both the compressive interlaminar shear strength, which is a measure of the bond strength between the fiber and the matrix resin, and the post-impact compressive strength, which is an index of impact resistance, are significantly low.

(Comparative Example 4) In Example 7, the tensile strength of the resin-impregnated strand of carbon fiber of which the surface treatment was carried out under the same conditions except that the amount of electrolysis was 750 coulomb was 38
4 kgf / mm ² , resin-impregnated strand tensile modulus 44600 kgf /
The peak height ratio in mm ² and Raman spectroscopy was 1.08.
For this carbon fiber, a prepreg was prepared in the same manner as in Example 1, and the molded composite was measured.
Unidirectional tensile strength 209 converted to fiber volume content 60%
kgf / mm ² , tensile strength development rate 79.0%, compressive interlaminar shear strength 7.7 kgf / mm ² and post-impact compressive strength 14.4 kgf / mm
^{Was 2} . The results of these evaluations are also shown in Table 1. It can be seen that the compressive interlaminar shear strength is slightly improved as compared with the composite physical properties of Example 7, but the unidirectional tensile strength and the tensile strength development rate are extremely reduced.

(Comparative Example 5) Tensile strength of resin-impregnated strand of carbon fiber surface-treated under the same conditions as in Example 10 except that the amount of electrolysis was 300 coulombs.
389 kgf / mm ² , resin-impregnated strand tensile modulus 95 400 kg
The peak height ratio of f / mm ² and Raman spectroscopy was 0.38. A prepreg was made in the same manner as in Example 1 for this carbon fiber, and the unidirectional tensile strength 2 converted into a fiber volume content of 60% was measured for the molded composite.
24 kgf / mm ² , tensile strength development rate 92.2%, compressive interlaminar shear strength 4.2 kgf / mm ² , compressive strength after impact is 8.1 kgf / mm
^{Was 2} . The results of these evaluations are also shown in Table 1. Compared with the composite physical properties of Example 10, as in the case of Comparative Example 1, the unidirectional tensile strength was rather high, and therefore the tensile strength development rate was high, but the compression layer, which is a measure of the bonding force between the fiber and the matrix resin, was used. It can be seen that both the shear strength and the post-impact compression strength, which is an index of impact resistance, are significantly low.

(Comparative Example 6) In Example 10, resin-impregnated strands of carbon fiber surface-treated under the same conditions except that the amount of electrolysis was 2300 coulombs, tensile strength 322 kgf / mm ² , resin-impregnated strands Tensile modulus 95300
kgf / mm ² , and the peak height ratio of Raman spectroscopy was 0.68. For this carbon fiber, a prepreg was prepared in the same manner as in Example 1, and the molded composite was measured. Unidirectional tensile strength 1 converted to a fiber volume content of 60% 1
79 kgf / mm ² , tensile strength development rate 73.7%, compressive interlaminar shear strength 5.9 kgf / mm ² , compressive strength after impact is 10.9 kgf /
It was mm ² . The results of these evaluations are also shown in Table 1.
As compared with the composite physical properties of Example 10, it can be seen that the unidirectional tensile strength and the tensile strength development rate are extremely lowered.

[0045]

EFFECTS OF THE INVENTION To provide a heat-resistant composite material having excellent composite physical properties composed of carbon fiber and a heat-resistant resin, by improving the adhesive force of carbon fiber to a highly heat-resistant matrix resin such as polyimide or polybismaleimide. Became possible.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08L 79:08 C08L 79:08 (56) References JP-A-2-307967 (JP, A) JP-A-5-105773 (JP , A) JP-A-5-44155 (JP, A) JP-A-49-86453 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08J 5/06 B29B 15/08 C08L 79/00-79/08 D06M 11/00 D01F 9/12

Claims (3)

(57) [Claims] 1. A tensile elastic modulus of 30,000 kgf / mm ² or more and 50,000 kgf
/ mm less than ^2, the ratio of the peak heights of the Raman bands of Raman bands and 1350～1360Cm ^-1 of 1580～1600Cm ^-1 Raman spectroscopy 0.
Carbon fiber is from 90 to 1.10, and a thermal decomposition starting temperature after curing Ri Do from 250 ° C. or more resins, the resin is polyimide
And / or polybismaleimide, a heat-resistant composite material. 2. The tensile modulus of elasticity is 50,000 kgf / mm ² or more and 70,000 kgf.
/ mm less than ^2, the ratio of the peak heights of the Raman bands of Raman bands and 1350～1360Cm ^-1 of 1580～1600Cm ^-1 Raman spectroscopy 0.
Thermal decomposition starting temperature after carbon fibers and curing is 65 to 0.95 Ri is Do from 250 ° C. or more resins, the resin is polyimide
And / or polybismaleimide, a heat resistant composite material. 3. A tensile modulus of elasticity of 70000 kgf / mm ² or more 96000 kgf
/ mm less than ^2, the ratio of the peak heights of the Raman bands of Raman bands and 1350～1360Cm ^-1 of 1580～1600Cm ^-1 Raman spectroscopy 0.
Thermal decomposition starting temperature after carbon fibers and curing is 45 to 0.70 Ri is Do from 250 ° C. or more resins, the resin is polyimide
And / or polybismaleimide, a heat resistant composite material .