JP3975496B2 - Method for producing carbon fiber reinforced carbon composite material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inexpensive carbon fiber reinforced carbon composite material realized by improving the productivity of a molding process and a method for producing the same.
[0002]
[Prior art]
Generally, a carbon fiber reinforced carbon composite (hereinafter abbreviated as “C / C composite”) is a PAN-based, pitch-based, rayon-based carbon fiber, or a precursor fiber thereof, a thermosetting resin such as a phenol resin, or It is manufactured by impregnating or mixing a thermoplastic resin such as pitch, pressurizing and molding using a mold, and then firing at 600 to 2500 ° C. in a non-oxidizing atmosphere. A high-quality C / C composite material used for a brake material or the like generally has a thickness of 5 to 40 mm, a fiber content (hereinafter abbreviated as “Vf”) of 20 to 60 vol%, and a thickness of 1 to Compared with a thin heat-resistant panel of 2 mm or less or a heat insulating material having Vf of only a few percent, a thickness and Vf of a certain level or more are required.
[0003]
Various forms of fibers and resins of the C / C composite material before molding are known. Of these, when continuous fibers are used, a unidirectional (UD) prepreg sheet in which a resin is attached in a state where the fibers are aligned in one direction, or a two-dimensional or three-dimensional woven fabric. A sheet-like or block-like cloth to which a resin is attached later is known. When short fibers are used, a rod-like tow / prepreg that has been impregnated with a resin in a bundle of fibers and then cut to a certain length, a compound in which fibers and resin are kneaded into pellets, and fibers are defibrated. A thick mat (Japanese Patent Laid-Open No. Sho 62-119288), an assembly in which fibers are beaten in a solvent and then the solvent is removed to orient the fibers in a random direction (Japanese Patent Laid-Open No. Sho 62-96364). No.), or a sheet (Japanese Patent Application No. 1-279527) in which fibers are defibrated in a dry or wet manner and fibers are two-dimensionally oriented randomly is known.
[0004]
[Problems to be solved by the invention]
However, in the production of a C / C composite material, pressurization and thermoforming using a mold causes various adverse effects, and hinders cost reduction and productivity improvement. First of all, it takes a lot of work and time to assemble and disassemble the mold every time. Secondly, when heating the fiber / resin at the time of molding, since heating is performed through the mold, extra heating power and time are required to warm the mold. Thirdly, since heating is also performed through the mold, the temperature unevenness inside the mold is caused by the difference in the thickness of the mold depending on the location, and as a result, the quality of the obtained molded product depends on the location. Unevenness occurs. Fourthly, in order to constrain the direction perpendicular to the stacking direction in the mold, when high pressure is applied, excess resin / fiber concentrates in a small gap in the mold and flows / leaks out, and the fiber orientation It will be disturbed.
[0005]
[Means for Solving the Problems]
Therefore, in order to solve the above-described problems, the inventors have started investigation by focusing on C / C composite materials using short fibers whose cost is lower than that of long fibers. Furthermore, the C / C composite material has undergone a dimensional change in a long process after molding, and thus attention has been paid to the fact that machining is required in the middle or final stage. In other words, because of this machining process, it is not necessary for the molded product to satisfy the shape and dimensions of the final product, as in ordinary plastic materials, and the dimensional accuracy of the molded product may be low. become. Thus, the inventors reversed the idea and conducted extensive studies on a method of molding without using a mold. As a result, if a two-dimensional random sheet is used as the form of carbon fiber / resin, the thickness of the desired shape is high and Vf is high, without using a mold. The present inventors have found that a small number of molded bodies can be formed and have completed the present invention.
[0006]
That is, the object of the present invention is to make it possible to perform the process up to the formation of the C / C composite material as cheaply, conveniently and in a short time as possible, and the short fiber carbon fiber or its precursor fiber is two-dimensional random. A sheet containing resin is laminated to obtain a laminated sheet, and the laminated sheet is molded by pressing and heating only from the laminating direction without restraining the direction perpendicular to the laminating direction. A step of forming a body, wherein the pressurization and heating are performed in two stages of primary pressurization and secondary pressurization, and at a constant pressure of 1/10 to 1/2 of the secondary pressurization. Pressurize the laminated sheet, continuously reduce the thickness of the laminated sheet according to the softening of the resin, perform primary pressurization, and when the temperature reaches 60-500 ° C., secondary pressurize in reducing the laminated sheet thickness to a target thickness of the shaped body Excluding only excess resin without disturbing the two-dimensional random orientation of the carbon fiber, forming a plate-like molded body having the same shape as the sheet before molding, thick, high Vf, and less quality unevenness, It is characterized by carbonization, graphitization, densification and processing as required.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Details of the present invention will be described below.
Carbon fiber is classified into pitch type, PAN (polyacrylonitrile) type, rayon type, etc. depending on the raw material, and any kind of fiber can be used, including precursor fiber that becomes carbon fiber by firing. It is good, and a plurality of types may be mixed and used. The precursor fiber will be explained in more detail. After spinning the carbon fiber raw material pitch, PAN, rayon, etc., heat treatment while controlling the temperature in an air atmosphere, molecular crosslinking by oxidation, curing of the polymer In other words, the pitch system is called an infusible fiber, and the PAN system is called a flame resistant fiber.
[0008]
As the form of the carbon fiber, a sheet in which short-cut carbon fibers cut in advance are two-dimensionally oriented (hereinafter referred to as “two-dimensional random sheet”) is used. In the two-dimensional random sheet, short fibers are entangled with each other, and a binder is added in some cases, and the fibers are fixed so that the fibers do not move in the plane.
Therefore, even if the laminated sheet is pressed without using a mold and restraining the direction perpendicular to the lamination direction, the fibers do not flow and spread in the plane direction, and the shape of the laminated sheet is maintained. A molded body in which only the thickness is compressed can be obtained.
[0009]
When describing other fiber forms, first, continuous fibers are more expensive than short fibers, and further costs for sheeting and woven fabrics are increased, which increases raw material costs.
Therefore, continuous fibers are not preferable for providing an inexpensive production method. The short fiber shape other than the two-dimensional random sheet is a tow prepreg in which a bundle of short fibers is impregnated with resin, a compound in which short fibers and resin are kneaded and pelletized, or a short fiber is three-dimensionally. There are randomly oriented thick mats and the like. However, since these fibers are not entangled with each other or very weak, they cannot be formed into a specific shape without a mold, and spread in the surface direction when pressed. Therefore, it is difficult to obtain a thick molded body or a molded body having a high Vf.
[0010]
The carbon fiber has a length of 1 to 100 mm, preferably 3 to 50 mm. When the fiber length is too long, the fibers are entangled excessively to form a flock, making it difficult to disperse and a homogeneous sheet cannot be obtained. On the contrary, when the fiber length is too short, the entanglement between the fibers becomes weak, and the sheet itself cannot be formed. Even if a sheet can be formed, the handling property is very poor, and further, it becomes difficult to maintain a desired shape by spreading in the surface direction during pressing.
[0011]
There are various methods for producing a two-dimensional random sheet from short fiber carbon fibers, and the method is not particularly limited. For example, as a method for producing a sheet by dry defibration, a method of mechanically beating carbon fibers into a sheet, using a device such as a random webber, or a screen after floating and defibrating fibers in an air stream There is a method of sucking up. Also, as a production method by wet defibration, the fibers are dispersed in a solvent, defibrated using a device such as a beater or a pulper used in the paper industry, paper is made, and the attached solvent is removed by drying. There is a method to make a sheet.
[0012]
At this time, the degree of defibration of the carbon fiber is low defibration in which the fiber bundle remains from a high defibrated state in which the fibers are defibrated to one single fiber according to the required characteristics. Any state may be used up to a fine state. However, the lower the defibration, the weaker the entanglement between the fibers, and the easier it is to spread in the surface direction at the time of pressure molding.
[0013]
The basis weight of the sheet, that is, the weight of the carbon fiber per 1 m ² is 10 to 5000 g / m ² , preferably 10 to 1000 g / m ² , and particularly preferably 100 to 500 g / m ² . If the basis weight is below this range, the fibers do not come into contact with each other, and a sheet cannot be formed. In addition, if the basis weight is more than this range, the sheet thickness increases and three-dimensionality occurs, so that the sheet deviates from the two-dimensional random sheet and spreads in the surface direction when pressed, making it difficult to maintain a desired shape.
[0014]
As the resin to be attached to the carbon fiber sheet, a thermosetting resin such as a phenol resin or a furan resin may be used, or a thermoplastic resin such as petroleum-based or coal-based pitch may be used.
There are various methods for attaching the resin to the carbon fiber sheet. In general, a carbon fiber sheet is prepared in advance, the sheet is impregnated with a liquid resin diluted with a solvent, and then the solvent is removed by drying. In addition to being a matrix raw material during molding, the resin also acts as a binder to bond fibers together, improving the handleability of the sheet and suppressing the spread in the surface direction during pressure molding and maintaining the shape have.
[0015]
In the case where the carbon fiber sheet is formed by a wet process, the process can be simplified by simultaneously performing the attachment with the resin. That is, it is a method in which a solid resin in a granular or powder form is dispersed and mixed in a solvent together with carbon fibers to make paper, and then the solvent attached to the sheet is removed by drying. In this case, a solvent that dissolves the solid resin is not preferable as the solvent, and it is necessary to be safe and inexpensive because it consumes a large amount compared to the carbon fiber / solid resin, and water is most preferable. . In the solvent, a thickener such as polyethylene oxide or polyacrylamide may be added in order to improve the dispersibility of the carbon fiber and the solid resin and improve the handleability of the whole solution. Moreover, in order to improve the handleability of the sheet | seat after drying, and in order to adhere | attach fibers and suppress the spread to the surface direction at the time of pressure forming, you may add binders, such as polyvinyl alcohol and methylcellulose. This method also has the advantage that the resin particles are dispersed between the fibers, thereby suppressing the formation of flocs due to excessive entanglement between the fibers and improving the uniformity and flatness of the sheet. Further, when making paper, if the opening of the screen is masked so as to have a desired shape and size, a sheet having a required size and shape can be obtained directly, and there is no need to cut it before lamination.
[0016]
The amount of resin applied is adjusted so that the Vf of the carbon fiber after molding is usually 20 to 60%, preferably 30 to 50%. Below Vf, the quality of the final C / C composite material, such as strength and friction characteristics, is not excellent. Further, Vf beyond this cannot be realized with a composite material of short fibers.
Sheets obtained in this way are cut to the desired size and shape as necessary, stacked sheets with uniform shapes, aligned so that there is no lateral displacement between the stacked sheets, and set in a hot platen press To do. At this time, preferably, in order to avoid the adhesion of the resin to the hot platen, the laminated sheets are set on the hot platen press in a state of being sandwiched between release papers or metal plates of the same material and thickness.
[0017]
Pressing with a hot platen press is basically performed in two stages. First, the primary pressure is applied to the laminated sheet at a pressure 1/10 to 1/2 lower than the secondary pressure, and the laminated sheet is compressed to a thickness of 2 to 3 times the target thickness of the molded body, and the secondary pressure is started. Preheat laminated sheet to temperature. If the pressure is applied before the resin is softened at a pressure higher than this, it is not preferable because the fiber breaks and the misalignment between the laminated sheets increases. In the present invention, since the inclusion having a large heat capacity such as a mold is not used, there is little heat loss, and the laminated sheet 3 can be heated to a desired temperature in a short time with low power. Further, since heat is transmitted from the upper and lower heating plates 1 to the laminated sheet only through the laminating direction, there is no unevenness in the sheet surface, and heating can be performed uniformly. In the stacking direction, there is a temperature difference that the surface layer near the hot platen has a high temperature and the center has the lowest temperature. However, this temperature difference can be reduced by reducing the thickness of the laminate during preheating. Rather than performing preheating at a constant thickness, continuing to pressurize at a constant pressure continuously reduces the laminate thickness in response to the softening of the resin, further increasing the heat transfer efficiency and increasing the temperature difference. Is preferable because the preheating time can be shortened and the moldable thickness can be increased. By reducing the temperature unevenness of the entire laminated sheet in this way, it is possible to suppress the quality unevenness of the obtained molded body. This unevenness can be easily confirmed by measuring the hardness of the surface of the molded body.
[0018]
The temperature at which the secondary pressurization starts is 60 to 500 ° C., and is preferably 5 to 30 ° C. lower than the temperature at which the resin viscosity is minimum. When the temperature is higher than this range, when a thermosetting resin is used, a curing reaction proceeds before pressurization, resulting in a molding failure, and an excessive amount of heat is consumed. Further, a temperature lower than this range is not preferable because an excessive pressure is required to pressurize to a target thickness because the viscosity of the resin is high and the fluidity is insufficient. The temperature at which the resin has the lowest viscosity corresponds to the gelation temperature in the case of a thermosetting resin, and can be measured and determined with a cone plate type rotational viscometer or the like. At the time of molding, it is desirable to monitor that the temperature of the laminated sheet is the highest, and the surface in contact with the hot platen is at this temperature, but it is not practical to insert the thermocouple 4 into the laminated sheet itself. The pressurization timing may be determined by measuring the temperature of the metal plate 2 between the laminated sheet 3 and the hot platen 1. By the secondary pressurization, the thickness of the laminated sheet is reduced to the target thickness of the plate-like molded body. The pressure of the pressurization is 10 to 300 kg / cm ^{2 as} a pressure per unit area of the molded body, and varies depending on the type of resin used and the desired Vf.
[0019]
In addition, production efficiency can also be raised by not performing preheating by a hot platen press among said processes. In this case, the laminated sheet is put into an oven or the like and heated in advance to a temperature corresponding to the secondary pressurization start temperature, which is lower by 5 to 30 ° C. than the temperature at which the resin has the lowest viscosity. Is set in a hot platen press heated to the same level or more, and immediately pressed to reduce the thickness of the laminated sheet to the target thickness of the molded body. By doing so, the time for heating and cooling the hot platen press between the room temperature and the pressurization start temperature can be omitted, so that the press occupation time can be shortened, which is preferable in terms of productivity. However, when using a thermosetting resin, if the preheating time outside the press of the laminated sheet is too long, the curing reaction will proceed and molding defects will occur during pressing. It is necessary to stay in a short time.
[0020]
When the plate-shaped molded product reaches the target thickness by pressurization, if a thermosetting resin such as phenol resin is used, it is further heated to a high temperature of 120 to 300 ° C to fully cure the resin. After cooling, the pressure is reduced, the molding is finished, and the plate-like molded body is taken out from the press. At this time, as in the case of heating, the present invention does not use an inclusion having a large heat capacity such as a mold, so that cooling can be completed in a short time. Further, when a thermoplastic resin such as pitch is used, the curing reaction does not occur. Therefore, cooling is performed when the plate-shaped molded body reaches the target thickness by pressurization. At this time, if the cooling is performed by a press different from that used during heating, the time required to occupy the hot platen press can be shortened, and the productivity can be increased. Thus, a molded body having a Vf of 20 to 60 vol% and a thickness of 5 to 40 mm can be obtained. The shape of the molded product is almost the same as the shape of the laminated sheet, but there are slight deviations and variations due to lateral deviation when the sheets are laminated and leakage of the resin. To.
[0021]
Next, the compact is fired (carbonized and graphitized) at a temperature of 800 to 2800 ° C. at a temperature rising rate of 1 to 200 ° C./h in an inert gas atmosphere such as nitrogen gas, and a C / C composite material. And At this point, the C / C composite material has a large number of pores and has such disadvantages as low strength, so that densification is performed. Note that it is preferable that the processing of the dimensions and shapes described above is performed at a stage before the densification treatment because it can be processed very easily. As the densification treatment, for example, methods such as pitch impregnation, resin impregnation, and CVD are used alone or in combination, and are repeated a plurality of times as necessary. Finally, if necessary, graphitization is performed by firing at a temperature of 800 to 2800 ° C. at a rate of temperature increase of 1 to 200 ° C./h in an inert gas atmosphere such as nitrogen gas. Thus, a C / C composite material excellent in strength and friction characteristics can be obtained.
[0022]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
Example 1
A pitch-based carbon fiber bundle having a fiber length of 30 mm is defibrated using a random webber to produce a sheet having a basis weight of 180 g / m ² in which carbon fibers are randomly oriented in two dimensions, and this is diluted with ethanol to a phenol resin. Impregnation was performed and ethanol was removed by drying to prepare a prepreg sheet having a resin adhesion rate of 40 wt%.
The temperature at which the resin had the lowest viscosity was measured at 105 ° C. using a cone-plate rotary viscometer. Therefore, the secondary pressurization start temperature was set to 80 ° C., which is 25 ° C. lower than that.
[0023]
The sheet is cut into a donut shape having an outer diameter of 350 mmφ and an inner diameter of 80 mmφ, 1815 g is laminated, and the surface is set on a hot platen press as shown in FIG. Preheating was started by heating the hot platen 1 to 90 ° C. while performing primary pressurization at a constant pressure of / cm ² . The thickness of the laminated sheet 3 at the start of pressurization and heating was 26 mm, which was more than twice the target thickness of the molded body. After 35 minutes, when the metal plate (iron plate) 2 sandwiching the laminated sheet reaches 80 ° C., the surface pressure is increased to 150 kg / cm ² and the secondary pressure is applied to reduce the laminated sheet thickness to 13 mm. I let you. Further, after 10 minutes from the start of the secondary pressurization, while maintaining the pressure of 150 kg / cm ² , the hot platen was heated to 250 ° C. in 30 minutes and held there for 30 minutes, and the temperature of the iron plate was kept at a maximum of 240 After the resin was sufficiently cured by heating to ° C., it was cooled, the pressure was reduced, and the molded body was taken out together with the iron plate. The time required for the hot platen press operation was as short as 150 minutes. Further, the molded body could be easily removed from the iron plate, and the resin did not adhere to the iron plate after removal, and could be easily maintained within 1 minute. The leaked resin adhered to the inner and outer circumferences of the molded body, which could be easily removed. The obtained molded body had an outer diameter of 350 to 355 mmφ, an inner diameter of 74 to 80 mmφ, a thickness of 12 mm, and Vf of 53%. Further, when the hardness of the plate surface was measured using a Rockwell hardness meter, it was 100 RHP and 99 RHP on the upper surface and the lower surface, respectively, and it was a molded product having no difference between the upper and lower surfaces.
This compact is fired up to 2000 ° C. in an inert atmosphere, and further, a densification step of impregnating this with a pitch, filling the pores, firing at 1000 ° C. in an inert atmosphere and carbonizing is repeated a plurality of times. Baking at 2000 ° C. in an inert atmosphere gave a C / C composite with a porosity of 10%.
[0024]
Comparative Example A prepreg sheet produced by the same raw material and production method as in Example 1 was cut into a donut shape having an outer diameter of 350 mmφ and an inner diameter of 80 mmφ, 1800 g was laminated in the mold, and the mold was set on a hot platen press. Then, after the primary pressure was applied until the thickness of the laminated sheet became about 25 mm, the hot platen was heated up to 150 ° C. while maintaining the thickness, and preheating was started. Then, when the side surface of the mold reached 77 ° C. after 60 to 75 minutes, the surface pressure was increased to 150 kg / cm ² and the secondary pressure was applied to reduce the laminated sheet thickness to 12 mm. Further, while maintaining the pressure of 150 kg / cm ² , the hot platen is heated to 250 ° C. in 80 minutes, held there for 60 minutes, and the mold is heated to 240 ° C. at the maximum temperature to sufficiently cure the resin. After cooling, the pressure was reduced and the mold was taken out. The time required for the hot platen press operation was 300 minutes, which was nearly twice as long as that of Example 1. In addition, since the leaked resin was cured in a state where it entered the gap between the molds, it was troublesome to disassemble the mold and take out the molded body, and to remove the resin adhering to the decomposed mold. It took about 60 minutes. The obtained molded body had an outer diameter of 350 mmφ, an inner diameter of 80 mmφ, a thickness of 11 mm, and a Vf of 52%. The hardness of the plate surface was 60 RHP and 80 RHP on the upper surface and the lower surface, respectively. .
This molded body was fired, densified, and heat-treated by the same production method as in Example 1 to obtain a C / C composite material having a porosity of 10%.
[0025]
Example 2
A pitch-based carbon fiber bundle with a fiber length of 30 mm and a granular resol-type phenol resin are blended at a weight ratio of 61:39 into a pulper filled with a polyethylene oxide aqueous solution with a concentration of 0.4 wt%, and defibrated by stirring. -After dispersion and mixing, a polyethylene oxide aqueous solution having a concentration of 0.4 wt% was further added to prepare a homogeneous slurry containing 0.5% by weight of carbon fibers and granular resin. This slurry was weighed 5.65 liters, put into a 350 mmφ cylinder, and sucked from above with a nozzle with a papermaking screen having an outer diameter of 350 mmφ and an inner diameter of 80 mmφ. And the sheet | seat obtained on the screen was dried at 40 degreeC for 24 hours, water | moisture content was removed, it had a donut shape with an outer diameter of 350 mmφ and an inner diameter of 80 mmφ, and the fibers were randomly oriented with a basis weight of 170 g / m ² A sheet in which granular resin having an adhesion rate of 39 wt% was uniformly dispersed was produced.
[0026]
1752 g of this sheet was laminated, and set in a hot platen press with an iron plate sandwiched between the upper and lower sides in the same manner as in Example 1, and pressurization heating molding was performed. However, since the resin used was different from Example 1 and the temperature at which the viscosity of the resin was the lowest was 125 ° C., the hot platen temperature for preheating and the secondary pressurization start temperature were 110 ° C. and 101 ° C., respectively. It was. The time required for the hot platen operation was 150 minutes, which was the same short time as the example. Moreover, the removal of the molded body was easy as in Example 1. The obtained molded body had an outer diameter of 350 to 360 mmφ, an inner diameter of 60 to 80 mm, a φ thickness of 12 mm, and Vf of 44%. Further, the hardness of the plate surface was 113 RHP and 109 RHP on the upper surface and the lower surface, respectively, and it was a molded product having no difference between the upper and lower surfaces.
This molded body was fired, densified and heat-treated by the same production method as in Example 1 to obtain a C / C composite material having a porosity of 11%.
[0027]
【The invention's effect】
According to the present invention, the process up to the formation of the carbon fiber reinforced carbon composite material can be performed inexpensively, simply and in a short time, thereby improving productivity, thereby supplying the carbon fiber reinforced carbon composite material at a lower cost. be able to.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a state during pressure heating according to the present invention.
[Explanation of symbols]
1 Hot plate 2 Metal plate 3 Laminated sheet 4 Thermocouple for metal plate temperature measurement

Claims (10)

A short fiber-like carbon fiber or its precursor fiber is randomly oriented two-dimensionally and a sheet containing a resin is laminated to obtain a laminated sheet, and the laminated sheet is not constrained in a direction perpendicular to the laminating direction. state, comprising the step of forming a shaped body by pressing and heating only the stacking direction, is performed by dividing the application of pressure and heat to the two stages of the primary pressure and secondary pressure, the secondary the laminated sheet at a constant pressure of 1 / 10-1 / 2 of pressure pressurized performs primary pressure continuously reduce the thickness of the laminated sheet according to the softening of the resin, temperature When the temperature reaches 60 to 500 ° C., secondary pressure is applied to reduce the thickness of the laminated sheet to the target thickness of the molded body.   A short fiber-like carbon fiber or its precursor fiber is randomly oriented two-dimensionally and a sheet containing a resin is laminated to obtain a laminated sheet, and the laminated sheet is not constrained in a direction perpendicular to the laminating direction. After forming the molded body by pressurizing and heating only from the laminating direction in the state, the laminated sheet is preheated to a temperature 5-30 ° C. lower than the temperature at which the resin has the lowest viscosity A method for producing a carbon fiber reinforced carbon composite material, wherein the pressure is applied by pressing into a press heated to a temperature higher than the temperature of the laminated sheet, and the thickness of the laminated sheet is reduced to a target thickness of the formed body. The carbon fiber according to claim 1 or 2, wherein a thickness of the molded body obtained through the step of forming the molded body by pressing and heating is 5 to 40 mm, and a fiber content is 20 to 60 vol%. A method for producing a reinforced carbon composite material.   The manufacturing method of the carbon fiber reinforced carbon composite material in any one of Claims 1-3 whose length of a short fiber-like carbon fiber or its precursor fiber is 1-100 mm. Carbon fibers or weight of the precursor fiber in the sheet 1 m ² is 10～5000G, method of producing a carbon fiber-reinforced carbon composite material according to any of claims 1 to 4. In the two-stage pressurization and heating, first, the sheet is compressed to a thickness of 2 to 3 times the target thickness, and heated while maintaining the pressure to gradually reduce the sheet thickness. When the temperature reaches 5 to 30 ° C. lower than the temperature at which the resin has the lowest viscosity, pressurization is performed at a higher pressure, and the laminated sheet thickness is reduced to the target thickness of the molded body. The manufacturing method of the carbon fiber reinforced carbon composite material of Claim 1 .   After making a sheet in which short fiber-like carbon fibers or precursor fibers thereof are two-dimensionally oriented in advance, the sheet is impregnated with a liquid resin diluted with a solvent, and then the solvent is dried and removed, whereby a resin is added to the carbon fiber. A method for producing a carbon fiber reinforced carbon composite material according to any one of claims 1 to 6, wherein the sheet is laminated, pressed and thermoformed.   A granular or powdered solid resin is dispersed and mixed in a solvent together with short fiber carbon fibers or precursor fibers thereof, and then papermaking and drying are performed to form a sheet in which the resin is attached to the carbon fibers. The manufacturing method of the carbon fiber reinforced carbon composite material in any one of Claims 1-6 which laminates | stacks, pressurizes and heat-molds.   The carbon fiber reinforced carbon composite material obtained from the manufacturing method as described in any one of Claims 1-8.   The brake sliding part which consists of a carbon fiber reinforced carbon composite material of Claim 9.

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