JP2019065269A - Carbon fiber composite material and manufacturing method of carbon fiber composite material - Google Patents

Abstract

To provide a carbon fiber composite material showing a large value of loss tangent (tanδ) while reinforcing with blending a carbon nanotube to a silicone rubber, and a manufacturing method of the carbon fiber composite material.SOLUTION: A carbon fiber composite material contains a silicone rubber, a carbon nanotube, and a coupling agent. The carbon nanotube has average diameter of 0.4 nm to 100 nm, and content in the carbon fiber composite material of 0.80 mass% or more and less than 6.50 mass%. The carbon fiber composite material has breaking number in a tear fatigue test at 120°C, maximum tensile stress of 1.5 N/mm and frequency of 1 Hz of 200,000 or more and loss tangent (tanδ) at 25°C of 0.15 or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a carbon fiber composite material in which carbon nanotubes are mixed with silicone rubber, and a method of manufacturing the carbon fiber composite material.

  Silicone rubber is characterized by a very wide use temperature range as compared to other rubbers, since the change in properties is small in a wide temperature range from low temperature to high temperature, but there is a problem that mechanical strength is low.

  A method of manufacturing a carbon fiber composite material excellent in abrasion resistance by disaggregating carbon nanotubes in silicone rubber has been proposed for use as a liner on which a prosthetic prosthetic device in the field of medical related equipment is mounted (see Patent Document 1) ). However, mechanical strength such as tensile strength is insufficient in other technical fields because the bonding strength between carbon nanotubes and silicone rubber is extremely weak.

  Therefore, the present inventors have improved the tensile strength and the tensile fatigue durability that can not be achieved by the mixing of ordinary silica particles by increasing the adhesive strength between carbon nanotubes and silicone rubber molecules using a silane coupling agent or the like. Has succeeded in developing a carbon fiber composite material of silicone rubber (see Patent Document 2). However, although this carbon fiber composite material was able to improve tensile strength and the like with carbon nanotubes, its flexibility as a rubber material was low, and the value of loss tangent (tan δ) was also small.

  Silicone rubber is expected to expand its applications utilizing its excellent temperature characteristics by improving its mechanical strength. On the other hand, even in such applications, flexibility as a rubber is often required. In vibration applications and the like, materials having a large loss tangent (tan δ) value are required.

JP, 2013-49752, A JP 2017-82145 A

  An object of the present invention is to provide a carbon fiber composite material exhibiting a large loss tangent (tan δ) value and a method for producing the carbon fiber composite material, while reinforcing and blending a carbon nanotube into silicone rubber.

  The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following aspects or application examples.

Application Example 1
The carbon fiber composite material according to the application example is
A carbon fiber composite material comprising a silicone rubber, a carbon nanotube, and a coupling agent,
The carbon nanotubes have an average diameter of 0.4 nm to 100 nm, and a content of 0.80% by mass or more and less than 6.50% by mass in the carbon fiber composite material,
The carbon fiber composite material has a breaking frequency of at least 200,000 in a tear fatigue test at 120 ° C., a maximum tensile stress of 1.5 N / mm, and a frequency of 1 Hz, and a loss tangent (tan δ) at 25 ° C. of 0.15. It is characterized by the above.

Application Example 2
In the carbon fiber composite material according to the application example,
The carbon nanotubes may be multi-walled carbon nanotubes having an average diameter of 5 nm to 100 nm.

Application Example 3
In the carbon fiber composite material according to the application example,
The carbon nanotubes may be multi-walled carbon nanotubes having an average diameter of 5 nm to 20 nm.

Application Example 4
In the carbon fiber composite material according to the application example,
The carbon nanotube may have a content of 0.97% by mass to 6.41% by mass in the carbon fiber composite material.

Application Example 5
In the carbon fiber composite material according to the application example,
The coupling agent is at least one selected from titanate coupling agents, silane coupling agents, aluminate coupling agents, and zirconate coupling agents.
The content of the coupling agent in the carbon fiber composite material may be 1% by mass to 10% by mass with respect to the content of the carbon nanotube.

Application Example 6
In the carbon fiber composite material according to the application example,
The compression residual strain after 1000 cyclic compression tests with a compression ratio of 25% can be 15.0% or less.

Application Example 7
The method for producing a carbon fiber composite material according to the application example is
Mixing a carbon nanotube having an average diameter of 0.4 nm to 100 nm with a silicone rubber, and a coupling agent to obtain a mixture;
The above-mentioned mixture is inserted into an open roll of 0 to 50 ° C. with a roll distance of 0.5 mm or less, and the carbon nanotube is disintegrated in silicone rubber,
Cross-linking step of cross-linking the mixture obtained in the thinning step to obtain a carbon fiber composite material;
Including
The content in the carbon fiber composite material is 0.80% by mass or more and less than 6.50% by mass,
The carbon fiber composite material has a breaking frequency of at least 200,000 in a tear fatigue test at 120 ° C., a maximum tensile stress of 1.5 N / mm, and a frequency of 1 Hz, and a loss tangent (tan δ) at 25 ° C. of 0.15. It is characterized by the above.

  According to the present invention, it is possible to provide a carbon fiber composite material exhibiting a large value of loss tangent (tan δ) and a method of manufacturing the carbon fiber composite material, while blending and reinforcing carbon nanotubes in silicone rubber.

It is a figure which shows typically the manufacturing method of the carbon fiber composite material which concerns on one Embodiment. It is a figure which shows typically the manufacturing method of the carbon fiber composite material which concerns on one Embodiment. It is a figure which shows typically the manufacturing method of the carbon fiber composite material which concerns on one Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. Further, not all of the configurations described below are necessarily essential configuration requirements of the present invention.

A. Carbon fiber composite material A carbon fiber composite material according to the present embodiment is a carbon fiber composite material containing a silicone rubber, a carbon nanotube, and a coupling agent, and the carbon nanotube has an average diameter of 0.4 nm to 100 nm, and the content in the carbon fiber composite material is 0.80% by mass or more and less than 6.50% by mass, and the carbon fiber composite material has a maximum tensile stress of 1.5 N / mm at 120 ° C., a frequency It is characterized in that the number of breakage in a 1 Hz tear fatigue test is 200,000 or more and a loss tangent (tan δ) at 25 ° C. is 0.15 or more.

  Moreover, the compounding agent generally used for silicone rubber can be used for carbon fiber composite material other than a carbon nanotube and a coupling agent.

A-1. Silicone rubber The silicone rubber used in one embodiment is not particularly limited, but can be a crude rubber of organopolysiloxane, the main chain is constituted by a siloxane bond, and a methyl group, an ethyl group, a propyl group, and a butyl side chain Alkyl group such as alkyl group, cycloalkyl group such as cyclohexyl group, alkenyl group such as vinyl group, allyl group, butenyl group and hexenyl group, aryl group such as phenyl group and tolyl group, benzyl group and γ-phenylpropyl group Aralkyl group or a group in which part or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with a halogen atom, cyano group or the like, for example, chloromethyl group, trifluoropropyl group, cyanoethyl group etc. it can. The molecular structure of the silicone rubber can be linear, and can be linear with some branching.

  For the silicone rubber, a known crosslinking agent can be used. For example, condensation type reaction, addition type reaction, peroxide reaction can be used as a crosslinking form, and peroxide crosslinking is preferable. By crosslinking silicone rubber with a crosslinking agent, a carbon fiber composite material excellent in heat resistance and chemical resistance can be produced.

  Moreover, as a silicone rubber, the silicone rubber compound with which the silica is previously mix | blended is included. Commercially available silicone rubbers are usually formulated with silica. Although silicone rubber is characterized by having excellent properties at a wide temperature range from low temperature to high temperature, a compound in which silica particles are previously compounded is generally used because of low physical strength.

A-2. Carbon Nanotube The carbon nanotube used in one embodiment of the present invention has an average diameter (fiber diameter) of 0.4 nm to 100 nm. Furthermore, the carbon nanotubes can have an average diameter (fiber diameter) of 5 nm to 100 nm, and in particular, an average diameter (fiber diameter) of 5 nm to 20 nm. The average diameter of the carbon nanotubes can be measured by observation with an electron microscope. The carbon nanotubes can also be oxidized to improve the reactivity with the silicone rubber on the surface. In the detailed description of the present invention, the average diameter and the average length of the carbon nanotubes are 200 points or more in diameter and length, for example, from imaging of 5,000 times with an electron microscope (the magnification can be appropriately changed according to the size of the carbon nanotubes). Can be calculated and obtained as its arithmetic mean value.

  In addition, carbon nanotubes are weak in adhesiveness with silicone rubber as described above, and when carbon nanotubes are compounded in silicone rubber, they are easily combined with the crosslinking agent of silicone rubber to cause crosslinking inhibition.

  The microcell structure formed by carbon nanotubes in the carbon fiber composite material can be formed to surround the matrix material by a network structure in which the carbon nanotubes are circulated in three dimensions. From the results of the previous research, it is known that the maximum diameter of one cell is approximately 2 to 10 times the average diameter of carbon nanotubes.

  The content of carbon nanotubes in the carbon fiber composite material is 0.80% by mass or more and less than 6.50% by mass. Furthermore, the content of carbon nanotubes in the carbon fiber composite material can be 0.97% by mass to 6.41% by mass, and can be 2.85% by mass to 5.54% by mass. When the carbon fiber composite material contains 0.80% by mass or more of carbon nanotubes, mechanical properties, particularly tear fatigue resistance at 120 ° C., can be improved. When the carbon fiber composite material contains carbon nanotubes in an amount of less than 6.50% by mass, the loss tangent (tan δ) can exhibit a large value.

  The carbon nanotube is a single-walled carbon nanotube (SWNT: single wall carbon nanotube) having a cylindrical shape obtained by winding a single sheet surface (graphene sheet) of carbon hexagonal network surface into a cylindrical shape, multi-walled carbon nanotube (MWNT: multiwall carbon) Can be nanotubes). Multi-walled carbon nanotubes include double-walled carbon nanotubes (DWNT: double-walled carbon nanotubes). In addition, carbon materials partially having a carbon nanotube structure can also be used. In addition to the name of carbon nanotube, it may be called by the name of graphite fibril nanotube or vapor grown carbon fiber.

  Carbon nanotubes can be obtained by vapor phase growth. The vapor phase growth method is also referred to as catalytic chemical vapor deposition (CCVD), and gas such as hydrocarbon is pyrolyzed in the vapor phase in the presence of a metal-based catalyst to obtain an untreated first carbon nanotube. How to make To describe the vapor phase growth method in more detail, for example, organic compounds such as benzene and toluene are used as raw materials, organic transition metal compounds such as ferrocene and nickel sen are used as a metal catalyst, and these are heated together with a carrier gas at a high temperature of 400 ° C. Floating reaction method in which the first carbon nanotubes are formed in the floating state or on the reaction furnace wall by introducing into a reaction furnace set to a reaction temperature of 1000 ° C. to 1000 ° C., and ceramics such as alumina and magnesium oxide in advance A catalyst supported reaction method (Substrate Reaction Method) or the like in which a metal-containing particle supported on top is brought into contact with a carbon-containing compound at a high temperature to form carbon nanotubes on a substrate can be used.

A-3. Coupling Agent The coupling agent used in one embodiment is one or more selected from a titanate coupling agent, a silane coupling agent, an aluminate coupling agent, and a zirconate coupling agent.

  As the silane coupling agent, those of Shin-Etsu Chemical Co., Ltd., Toray Industries, Inc., Momentive Performance Materials Co., Ltd. can be used, and examples thereof include 3-methacryloxypropyltrimethoxysilane and 3-glycidoxypropyltrimethoxy. Silane, 3-mercaptopropyltrimethoxysilane and the like can be used.

  As the titanate coupling agent, the aluminate coupling agent and the zirconate coupling agent, those of Ajinomoto Co., KENRICH, etc. can be used, and as the titanate system, for example, tetra (2,2diallyloxymethyl) butyl And di (ditridecyl) phosphite titanate etc. can be used, for example, alkyl acetoacetate aluminum diisopropylate etc. can be used as the aluminate system, tetra (2,2 diallyloxymethyl) butyl as the zirconate system Di (ditridecyl) phosphite zirconate etc. can be used.

  The coupling agent can have two or more types of reactive groups in the molecule, one of which is an organic functional group for silicone rubber and the other one is a hydrolyzable group for carbon nanotubes Can. The organic functional group having adhesiveness to silicone rubber includes an amino group, a vinyl group, a methacrylic group, an epoxy group and the like. The hydrolyzable group having adhesiveness to carbon nanotubes includes a methoxy group, an ethoxy group, a 2-methoxyethoxy group and the like.

  The compounding amount of the coupling agent can be appropriately set according to the compounding amount of the carbon nanotube compounded to the carbon fiber composite material. For example, the content of the coupling agent in the carbon fiber composite material is set to be 1% by mass to 10% by mass with respect to the content of the carbon nanotube (for example, the carbon nanotube blended in the carbon fiber composite material is If it is 10 g, the coupling agent can be 0.1 g to 1 g), and in particular, it can be 2 mass% to 7 mass% with respect to the content of carbon nanotubes.

  When the carbon fiber composite material contains a coupling agent, one reactive group of the coupling agent is linked to the silicone rubber molecule, and the other reactive group of the coupling agent is reacted with the functional group on the surface of the carbon nanotube. Improve the compatibility and adhesion between rubber and carbon nanotubes. Further, reaction of the reactive group of the coupling agent with the functional group of the carbon nanotube can prevent the functional group of the carbon nanotube from reacting with the crosslinking agent to inhibit the crosslinking of the silicone rubber.

A-4. Other compounding agents For silicone rubber, which are used as general compounding agents of rubber, for example, silica, alumina, metal oxides such as magnesium oxide and zinc oxide, reinforcing agents such as carbon black, talc, clay, graphite Fillers such as calcium silicate, processing aids such as stearic acid, palmitic acid, and paraffin wax, anti-aging agents, plasticizers and the like can be added as needed. Although carbon black and graphite have little effect as a mechanical reinforcement of the carbon fiber composite material, improvement in kneading processability can be expected.

A-5. Tear-Fatigue Durability The tear-fatigue durability of a carbon fiber composite material is subjected to a tear-fatigue test and evaluated by the number of times a test piece breaks. In the tear fatigue test, a test piece of carbon fiber composite material (20 mm × width 4 mm × thickness 1 mm, cut 1 mm deep in the width direction from the center of the long side of the test piece) at 120 ° C., frequency 1 Hz in the atmosphere. Under the conditions of (1), the maximum tensile stress is applied repeatedly under repeated tensile load (0 N / mm to 1.5 N / mm, 0 N / mm to 3 N / mm) under the conditions of 1.5 N / mm and 3 N / mm. In the tearing fatigue test, a test piece of carbon fiber composite material (20 mm × width 4 mm × thickness 1 mm, depth 1 mm from the center of the long side of the test piece under the condition of high temperature)
In the air, at a temperature of 200 ° C and a frequency of 1 Hz, under a condition of maximum tensile stress of 2N / mm and 4N / mm, repeated tensile load (0N / mm to 2N / mm, 0N / mm) You may go through by 4N / mm).

  The carbon fiber composite material has a number of breakages of at least 200,000 in a tear fatigue test at 120 ° C., a maximum tensile stress of 1.5 N / mm, and a frequency of 1 Hz. In the carbon fiber composite material, the number of breakage can be 200 or more when the maximum tensile stress in the test is 3 N / mm, and the number of breakage in the same test (3 N / mm) is 500 or more Can. The carbon fiber composite material can be broken more than 200 times in a tear fatigue test at 200 ° C., maximum tensile stress 2 N / mm, and frequency 1 Hz, and furthermore, the number of breaks in the same test (2 N / mm) is 200,000 It can be more than. In the carbon fiber composite material, when the maximum tensile stress in the test is 4 N / mm, the number of breakages can be 30 times or more, and furthermore, the number of breakages in the same test (4 N / mm) is 4,000 or more Can.

  The carbon fiber composite material of the present invention can be excellent in tear fatigue durability by disentangling and dispersing the carbon nanotubes and reinforcing the whole, even if the carbon nanotubes are relatively small amount.

A-6. Loss tangent The loss tangent of the carbon fiber composite material is obtained by conducting a dynamic viscoelasticity test and measuring the loss tangent (tan δ) at 25 ° C. In the dynamic viscoelasticity test, a test piece of carbon fiber composite material (40 mm × 1 mm × 2 mm), distance between chucks 20 mm, measurement temperature -130 to 300 ° C. (heating rate 3 ° C./min), dynamic strain ± 0 The dynamic viscoelasticity test is carried out based on JIS K 6394 at a frequency of 1 Hz. From the test results, the loss tangent (tan δ) at 25 ° C. can be determined.

  The carbon fiber composite material has a loss tangent (tan δ) at 25 ° C. in the same test of 0.15 or more. In the carbon fiber composite material, the loss tangent (tan δ) at 25 ° C. in the same test when measured in the tensile mode with respect to the grain direction of the test piece can be 0.15 to 0.20, and 0 It can be .16 to 0.19. The grain direction is a direction along the direction of dispensing with open rolls.

  Since the carbon fiber composite material contains a small amount of carbon nanotubes, it has flexibility as a rubber and can exhibit a large loss tangent value.

A-7.50% modulus 50% modulus (σ 50) of a carbon fiber composite material is obtained by conducting a tensile test and measuring stress (MPa) at 50% strain. The tensile test is performed at 23 ° C. ± 2 ° C. and a tensile speed of 500 mm / min using JIS No. 6 dumbbell (standard line distance 20 mm) in accordance with JIS K6251.

  The 50% modulus of the carbon fiber composite material can be 2 MPa or more. The carbon fiber composite material can be reinforced by carbon nanofibers to exhibit a 50% modulus of 2 MPa or more.

A-8. Compressive Residual Strain The compressive residual strain of the carbon fiber composite material is obtained by measuring the residual strain after 1000 cyclic compression tests with a compression rate of 25% and calculating it from the measured value. In the cyclic compression test, using a sample of φ12 mm × height 4 mm, the frequency is 1 Hz, the number of repetitions is 1000 times, room temperature, and the compression ratio is 0% and 25%. The compressive residual strain is calculated by measuring the height of the sample after 30 minutes after cyclic compression test, and dividing the initial height of the sample by the height after the test divided by the initial height {(initial value Height-height after test) / initial height}.

  The compressive residual strain of the carbon fiber composite material can be smaller than the compressive residual strain of a single rubber component not containing carbon nanotubes. The compressive residual strain of the carbon fiber composite material can be 15.0% or less. That the compression residual strain of the carbon fiber composite material is small means that the compression fatigue property is excellent.

B. Method for Producing Carbon Fiber Composite Material The method for producing a carbon fiber composite material according to the present embodiment is a mixture in which a carbon nanotube having an average diameter of 0.4 nm to 100 nm and a coupling agent are mixed with silicone rubber. Mixing step of obtaining the mixture, a thin threading step of defibrillating carbon nanotubes in silicone rubber by charging the mixture to an open roll of 0 to 50 ° C. with a roll distance of 0.5 mm or less, and the thin threading step Crosslinking the obtained mixture to obtain a carbon fiber composite material, the content in the carbon fiber composite material is 0.80% by mass or more and less than 6.50% by mass, and the carbon fiber composite material is The number of fractures in a tear fatigue test at 120 ° C., maximum tensile stress 1.5 N / mm, and frequency 1 Hz is 200,000 or more, and loss tangent at 25 ° C. (t It is characterized in that an δ) is 0.15 or more.

  The method for producing a carbon fiber composite material will be described in detail with reference to FIGS. 1 to 3 schematically show a method of manufacturing a carbon fiber composite material by an open roll method according to an embodiment of the present invention.

  As shown in FIGS. 1 to 3, the first roll 10 and the second roll 20 in the two-roll open roll 2 are disposed at a predetermined distance d, for example, 0.5 mm to 1.5 mm. 1 to 3 and rotates in the forward and reverse directions at rotational speeds V1 and V2 in the directions indicated by the arrows in FIGS.

  First, as shown in FIG. 1, the silicone rubber 30 wound around the first roll 10 may be masticated, and the silicone rubber molecular chain is appropriately cut to generate free radicals. The free radicals of silicone rubber generated by mastication are in a state of being easily combined with carbon nanotubes.

B-1. Mixing Step Next, as shown in FIG. 2, the carbon nanotubes 80, the coupling agent 82 and other fillers are charged into the bank 34 of the silicone rubber 30 wound around the first roll 10, and the mixture is kneaded. Get The temperature of the silicone rubber 30 in this kneading can be, for example, 0 ° C. to 50 ° C., and can further be 10 ° C. to 20 ° C. The step of mixing the silicone rubber 30 with the carbon nanotube 80 and the coupling agent 82 is not limited to the open roll method, and for example, a closed kneading method or a multi-screw extrusion kneading method can also be used.

  Here, the method of feeding the carbon nanotubes 80 and the coupling agent 82 directly to the roll is called a so-called integral blending method. Because it can be compounded in one step, it is easy to be adopted industrially. Further, in terms of uniform treatment, there is a method of adding a coupling agent to carbon nanotubes in advance by a dry treatment method or a wet treatment method.

  The description of the type and amount of the filler composition is as described above, and is thus omitted. Although water is added to hydrolyze the hydrolyzable group of the coupling agent, the water may be added to the carbon nanotube in advance together with the coupling agent.

B-2. Further, as shown in FIG. 3, the roll gap d between the first roll 10 and the second roll 20 is set to, for example, 0.5 mm or less, more preferably 0 mm or more and 0.5 mm or less. The mixture 36 is put into the open roll 2 and thinned.

  The number of times of thinning may be, for example, about once to about 10 times.

  Assuming that the surface speed of the first roll 10 is V1 and the surface speed of the second roll 20 is V2, the surface speed ratio (V1 / V2) of the two in lapping is 1.05 to 3.00. It is preferable that it is 1.05 to 1.2. A desired shear force can be obtained by using such a surface velocity ratio.

  The carbon fiber composite material 50 extruded from such narrow rolls is largely deformed as shown in FIG. 3 due to the resilience of the silicone rubber, and at that time, the carbon nanotubes move largely together with the silicone rubber.

  The carbon fiber composite material 50 obtained by thining is rolled by a roll and divided into sheets of a predetermined thickness.

  In this thinning step, the roll temperature is set to a relatively low temperature of, for example, 0 to 50 ° C., more preferably 5 to 30 ° C., in order to obtain as high a shear force as possible. It can be adjusted to 0 to 50 ° C.

  The shear force thus obtained causes a high shear force to act on the silicone rubber, separating the carbon nanotubes from one another so as to be pulled out one by one to the silicone rubber molecules, and disentangling the silicone rubber. Distributed throughout. In particular, since silicone rubber has elasticity, viscosity, and chemical interaction with carbon nanotubes, carbon nanotubes can be easily dispersed. And the carbon fiber composite material 50 excellent in the dispersibility and dispersion stability (it is hard to reaggregate a carbon nanotube) of a carbon nanotube can be obtained.

  More specifically, when silicone rubber and carbon nanotubes are mixed in an open roll, viscous silicone rubber penetrates into each other of carbon nanotubes, and certain parts of silicone rubber are chemically interacted with each other by chemical interaction. It binds to the highly active part. If the surface activity of the carbon nanotube is moderately high, it can be particularly easily bonded to silicone rubber molecules. Next, when a strong shearing force acts on the silicone rubber, the carbon nanotubes also move along with the movement of the silicone rubber molecules, and the carbon nanotubes separated are separated by the resilience of the silicone rubber due to the elasticity after shearing. , Will be dispersed in silicone rubber.

  According to the present embodiment, when the carbon fiber composite material is extruded from a narrow roll, the carbon fiber composite material is deformed to be thicker than the roll interval due to the resilience due to the elasticity of the silicone rubber. The deformation can be inferred to make the carbon fiber composite material subjected to the strong shear force more complicated and to disperse the carbon nanotubes in the silicone rubber. Then, carbon nanotubes once dispersed can be prevented from reaggregation due to chemical interaction with silicone rubber, and can have good dispersion stability.

The thinning step is not limited to the open roll method as long as carbon nanotubes can be broken into silicone rubber by a shearing force, and a closed kneading method or a multi-screw extrusion kneading method can also be used. In short, in this step, it is only necessary to apply a shearing force to the silicone rubber which can separate and break up the aggregated carbon nanotubes. In particular, the open roll method is preferred as it can measure and control the actual temperature of the mixture, as well as control of the roll temperature. In cases other than the open roll method, in order to obtain an appropriate shearing force, it is preferable to set the temperature of the mixture during kneading to the above temperature range of the roll.

B-3. Heat Treatment Step The thin carbon fiber composite material can be removed from the open roll 2 and heated in an oven at 100 ° C. to 200 ° C. for 10 minutes to 1 hour to promote the hydrolysis of the coupling agent.

  The heat-treated carbon fiber composite material is wound around the first roll 10 again, a crosslinking agent is added, and the roll gap is set to a predetermined gap (1.1 mm) to separate the carbon fiber composite material. The addition of the crosslinking agent can be performed on the dispensed carbon fiber composite material before, during or after mixing of the silicone rubber and the carbon nanotube.

B-4. Crosslinking process (molding process)
A carbon fiber composite material (crosslinked body) can be obtained by peroxide crosslinking or addition crosslinking of the carbon fiber composite material (uncrosslinked body). As the crosslinking agent, known ones can be adopted, and in particular, an optimum one may be adopted depending on the kind of silicone rubber.

  The carbon fiber composite material produced in this manner can have the characteristics described in the above A-5 and A-6.

  As described above, although the embodiments of the present invention have been described in detail, those skilled in the art can easily understand that many modifications can be made without departing substantially from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included within the scope of the present invention.

(1) Preparation of sample The sample of the example was produced by the following steps.

  Kneading step: A silicone rubber was charged into an open roll (roll temperature: 10 to 20 ° C.) having a roll diameter of 6 inches, and was wound around the roll (see FIG. 1).

  Next, compounding agents such as carbon nanotubes (“MWCNT”, “coupling agent” in Tables 1 and 2) so as to obtain the mixing ratio (% by mass of the compounding agent in the carbon fiber composite material) shown in Tables 1 and 2 And “crosslinking agent etc.” were introduced into the silicone rubber (see FIG. 2). At this time, the roll gap d was 1.5 mm. In addition, the coupling agent and the water | moisture content were previously contained in the carbon nanotube before injection | pouring. The water content was 4% by mass with respect to the compounded amount of carbon nanotubes, and the compounded amount of carbon nanotubes in the table described the compounded amount before containing the water.

  Thinning step: The heat-treated mixture was charged with the roll gap d narrowed to 1.5 mm to 0.3 mm, and the first mixture was obtained (see FIG. 3). At this time, the surface velocity ratio of the two rolls was set to 1.1. The thinning was repeated 5 times.

  Heat treatment step: The diluted mixture was removed from the roll and heated in an oven at 150 ° C. for 30 minutes to promote the hydrolysis of the coupling agent.

  Furthermore, the heat-treated mixture was wound around a roll again, a crosslinker was added, and the roll was set in a predetermined gap (1.1 mm) to dispense an uncrosslinked mixture.

  Molding step: The uncrosslinked mixture was introduced into a vacuum press and press molded (primary vulcanization) at 150 ° C. to 170 ° C. for 5 minutes to 30 minutes.

  Furthermore, the primary vulcanized mixture was transferred to an oven, and secondary vulcanization was performed at 200 ° C. for 4 hours to obtain peroxide-crosslinked sheet-like carbon fiber composite material samples of Examples 1-5. The samples of Comparative Examples 1 and 2 were obtained in the same manner as in Example.

  In Tables 1 and 2, the details of silicone rubber and various compounding agents were as follows (silicone rubber is mainly composed of a silicone polymer having a siloxane bond consisting of a bond of silicon and oxygen as a skeleton and silica) compound). Moreover, about the coupling agent of Examples 1-5 and the comparative example 1, 4 mass% was mix | blended with respect to the carbon nanotube (Coupling so that it might become 4 mass% when the compounded carbon nanotube is 100 mass%. Formulated the agent). The sample of the comparative example 2 mix | blended 0.50 mass% of crosslinking agents which have a peroxide as a main component with silicone rubber.

The compounding agents shown in Tables 1 and 2 below are
Silicone rubber: Shin-Etsu Chemical Co., Ltd. product name KE-5560-U,
MWCNT: multiwall carbon nanotubes, average diameter 10.5 nm,
Silane system: 3-methacryloxypropyl trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.),
Crosslinking agent, etc .: 2,5-dimethyl-2,5-di (t-butylperoxy) hexane.

(2) Dynamic Viscoelasticity Test Using the dynamic viscoelasticity tester DMS 6100 manufactured by SII for the samples of Examples and Comparative Examples as test pieces of strip 40 mm × 1 mm × 2 mm (width), the distance between chucks Dynamic viscoelasticity test was performed based on JIS K 6394 at 20 mm, measurement temperature -130 to 300 ° C (heating rate 3 ° C / min), dynamic strain ± 0.05%, frequency 1 Hz, loss tangent at 25 ° C ( tan δ) was measured. The dynamic viscoelasticity test was performed in tension mode with respect to the grain direction of the test piece. The measurement results of the loss tangent (tan δ) at 25 ° C. are shown in Tables 1 and 2.

(3) Tear fatigue test The samples of Examples and Comparative Examples are punched into a 20 mm × 4 mm × 1 mm thick strip-shaped test piece, and a 1 mm-depth incision is made in the width direction from the center of the long side of the test piece. The maximum tensile stress is 2N / mm under the conditions of 200 ° C and a frequency of 1Hz in the atmosphere using a TMA / SS6100 tester manufactured by SII (4) Tear fatigue test is conducted by applying repeated tensile load (0 N / mm to 2 N / mm, 0 N / mm to 4 N / mm) under the following conditions (“tear fatigue life -2” in the table) and the test piece breaks The number of times of tension (fatigue life (times)) was measured. The measurement results are shown in the column of "Tear fatigue life-1" (maximum 2 N / mm) and "Tear fatigue life-2" (maximum 4 N / mm) in the table.

Furthermore, the samples of the example and the comparative example are punched into a 20 mm × 4 mm × 1 mm thick strip-shaped test piece, and a 1 mm-deep cut is made in the width direction from the center of the long side of the test piece. A maximum tensile stress of 1.5 N / mm (Table: "Tear fatigue life-3") and 3 N / mm in the atmosphere at 120 ° C and a frequency of 1 Hz using a TMA / SS 6100 tester A tearing fatigue test is carried out by applying repeated tensile loads (0 N / mm to 1.5 N / mm, 0 N / mm to 3 N / mm) with (Tear fatigue life-4 in the table), and the test piece breaks. The number of times of tension (fatigue life (times)) was measured. The measurement results are shown in the columns of "tear fatigue life -3" (maximum 1.5 N / mm) and "tear fatigue life -4" (maximum 3 N / mm) in the table.

  In each of the tear fatigue tests, the number of times of tension was up to 200,000, and when it did not break at 200,000, it was described as "200,000 (discontinued)" in the table. In Comparative Example 2, the test of 4 N / mm was not performed.

(4) Hardness The rubber hardness (Hs (JIS A)) was measured based on the JIS K6253 test about the sample of an Example and a comparative example. The measurement results are shown in Tables 1 and 2.

(5) Tensile test The tensile strength (TS (MPa)), the elongation at break (Eb (%)), and the stress at 50% deformation (σ 50 (MPa)) of the samples of the example and the comparative example Based on JIS K6251 at 23 ± 2 ° C, standard line distance 20 mm, tensile speed 500 mm / min using a tensile tester Autograph AG-X manufactured by Shimadzu Corporation. The tensile test was performed to measure. The measurement results are shown in Tables 1 and 2.

(6) Compression Test The samples of Examples and Comparative Examples were subjected to 1000 repeated compression tests, and residual strain after the test was measured. In the cyclic compression test, using a sample of φ12 mm × height 4 mm, compression from 0% compression (initial state) to 25% compression at room temperature and then return to 0% compression as a single compression Repeated at frequency 1 Hz up to 1000 times. The residual strain was measured the height of the sample after 30 minutes from the compression test, and the "compression residual strain" was divided by the initial height of the sample minus the height after the test (compression strain) divided by the initial height. It was calculated by the value {(initial height−height after test) / initial height}. The calculation results are shown in Tables 1 and 2.

  According to Tables 1 and 2, the samples of Examples 1 to 5 had more tear fatigue life times than Comparative Examples 1 and 2. The samples of Examples 1 to 5 had a “tearing fatigue life −1” of 200 or more, and the samples of Examples 2 to 5 had a “tearing fatigue life of 1” of 200,000 or more. Also, the samples of Examples 1 to 5 had a “tear fatigue life -2” of 30 or more, and the samples of Examples 2 to 5 had a “tear fatigue life of 2” of 4000 or more.

  The samples of Examples 1 to 5 had "tear fatigue life -3" of 200,000 or more, and the samples of Examples 1 to 5 had "Tear fatigue life-4" of 588 or more.

  Moreover, compared with the comparative example 1, the loss tangent (tan-delta) of the samples of Examples 1-5 was 0.16 or more.

  Moreover, in the samples of Examples 1 to 5, the value of “TS” was equal to or greater than that of Comparative Example 2, and the value of “σ 50” was larger than that of Comparative Example 2 and was 2.1 MPa or more. The samples of Examples 1 to 5 had a value of “Eb” larger than that of Comparative Example 1.

Furthermore, in the samples of Examples 1 to 5, the compression residual strain in the compression test was smaller than that of Comparative Example 1, and was 13.4% or less.

(5) Electron microscopic observation The tensile fracture surface of the sample of the example was observed with a scanning electron microscope. A disintegrated carbon nanotube could be observed in the carbon fiber composite material. In the sample of the example, aggregates of carbon nanotubes were not found.

  2 ... open roll, 10 ... first roll, 20 ... second roll, 30 ... silicone rubber, 34 ... bank, 36 ... mixture, 50 ... carbon fiber composite material, 80 ... carbon nanotube, 82 ... coupling agent, V1, V2 ... rotational speed, d ... roll gap

Claims (7)

A carbon fiber composite material comprising a silicone rubber, a carbon nanotube, and a coupling agent,
The carbon nanotubes have an average diameter of 0.4 nm to 100 nm, and a content of 0.80% by mass or more and less than 6.50% by mass in the carbon fiber composite material,
The carbon fiber composite material has a breaking frequency of at least 200,000 in a tear fatigue test at 120 ° C., a maximum tensile stress of 1.5 N / mm, and a frequency of 1 Hz, and a loss tangent (tan δ) at 25 ° C. of 0.15. More than that, carbon fiber composite material. In claim 1,
The carbon fiber composite material, wherein the carbon nanotube is a multi-wall carbon nanotube having an average diameter of 5 nm to 100 nm. In claim 1 or 2,
The carbon fiber composite material, wherein the carbon nanotubes are multi-wall carbon nanotubes having an average diameter of 5 nm to 20 nm. In any one of claims 1 to 3,
The carbon fiber composite material, wherein a content of the carbon nanotube in the carbon fiber composite material is 0.97% by mass to 6.41% by mass. In any one of claims 1 to 4,
The coupling agent is at least one selected from titanate coupling agents, silane coupling agents, aluminate coupling agents, and zirconate coupling agents.
Content of the said coupling agent in the said carbon fiber composite material is carbon fiber composite material which is 1 mass%-10 mass% with respect to content of the said carbon nanotube. In any one of claims 1 to 5,
A carbon fiber composite material having a compressive residual strain of 15.0% or less after 1000 cyclic compression tests at a compressibility of 25%. Mixing a carbon nanotube having an average diameter of 0.4 nm to 100 nm with a silicone rubber, and a coupling agent to obtain a mixture;
A thin-passing step in which the carbon nanotube is defibrillated in silicone rubber by charging the mixture to an open roll at 0 to 50 ° C. with a roll distance of more than 0 mm and 0.5 mm or less;
Cross-linking step of cross-linking the mixture obtained in the thinning step to obtain a carbon fiber composite material;
Including
The content of the carbon fiber composite material is 0.80% by mass or more and less than 6.50% by mass,
The carbon fiber composite material has a breaking frequency of at least 200,000 in a tear fatigue test at 120 ° C., a maximum tensile stress of 1.5 N / mm, and a frequency of 1 Hz, and a loss tangent (tan δ) at 25 ° C. of 0.15. The manufacturing method of a carbon fiber composite material which is the above.

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