JP5051641B2 - Method for producing carbon fiber composite material - Google Patents

Description

The present invention relates to the production how the carbon fiber composite material using carbon nanofibers.

In general, carbon nanofibers are fillers that are difficult to disperse in a matrix . According to the method for producing a carbon fiber composite material previously proposed by the present inventors, it was possible to knead an elastomer and carbon nanofibers and uniformly disperse carbon nanofibers having high cohesiveness by shearing force (for example, Patent Document 1). More specifically, when the elastomer and the carbon nanofiber are mixed, the viscous elastomer penetrates into the carbon nanofiber, and a specific part of the elastomer has high activity of the carbon nanofiber due to chemical interaction. In this state, when a strong shearing force is applied to a mixture of an elastomer having high molecular mobility (elasticity) and carbon nanofibers, the carbon nanofibers are deformed as the elastomer is deformed. The fibers also moved, and the aggregated carbon nanofibers were separated and dispersed in the elastomer by the restoring force of the elastomer due to elasticity after shearing. Thus, by improving the dispersibility of the carbon nanofibers in the matrix, expensive carbon nanofibers can be used efficiently as fillers for composite materials.

  Moreover, according to the method for producing a carbon fiber composite material using the thermoplastic resin as a matrix previously proposed by the present inventors, the dispersibility of the carbon nanofibers in the thermoplastic resin matrix, which has been considered difficult so far, is improved. (See, for example, Patent Document 2).

  However, when a thermoplastic resin is used as a matrix, elasticity such as an elastomer is difficult to obtain in the kneading step, and the movement of the carbon nanofibers is small, so that further uniform dispersion of the carbon nanofibers has been demanded.

Ultra high molecular weight polyethylene (UHMWPE), polyetheretherketone (PEEK), and the like have been employed in the medical field, in particular, artificial joint members that are used in place of living joints (see, for example, Patent Document 3). Artificial joints are used by replacing knee joints, hip joints, elbow joints, finger joints and the like when they do not function sufficiently. Artificial joints are subject to repeated friction and load, so ultra high molecular weight polyethylene has a high demand for wear resistance on the contact surface.
JP 2005-97525 A JP 2005-336235 A JP 2002-301093 A

An object of the present invention is to provide a manufacturing how the carbon fiber composite material using carbon nanofibers.

The method for producing a carbon fiber composite material according to the present invention includes:
Step (a) in which an ultra high molecular weight polyethylene is introduced into an open roll having a roll set at a first temperature and wound around the roll, and further carbon nanofibers are added and mixed to obtain a mixture;
(B) disperse | distributing the said carbon nanofiber with a shearing force by throwing the said mixture into the open roll which has a roll set to 2nd temperature, and making it pass through thinly.
Including
The first temperature is a temperature at which the ultrahigh molecular weight polyethylene is melted and wound around the roll in the first step (a), and is higher than the second temperature.

  According to the method for producing a carbon fiber composite material according to the present invention, the ultrahigh molecular weight polyethylene can be melted to the extent that it is wound around the roll at the first temperature and mixed with the carbon nanofibers. ) Even in the above case, carbon nanofibers can be mixed in ultra-high molecular weight polyethylene in a powder state. Furthermore, by passing the mixture through at a second temperature lower than the first temperature, the carbon nanofibers are moved by the movement of the ultrahigh molecular weight polyethylene molecules due to elastic deformation like an elastomer, and the super-plastic resin. Carbon nanofibers can be uniformly dispersed in a high molecular weight polyethylene matrix. A carbon fiber composite material in which carbon nanofibers are uniformly dispersed has improved rigidity and excellent wear resistance, and improved heat resistance and can suppress adhesive wear.

In the method for producing a carbon fiber composite material according to the present invention,
The first temperature is equal to or higher than the flow start temperature of the ultra high molecular weight polyethylene and lower than the heat deterioration start temperature,
The second temperature may be equal to or higher than the melting temperature of the ultra high molecular weight polyethylene and lower than the flow start temperature.

In the method for producing a carbon fiber composite material according to the present invention,
The first temperature is 180 ° C. or higher and 230 ° C. or lower,
The second temperature may be 130 ° C. or higher and lower than 180 ° C.

In the method for producing a carbon fiber composite material according to the present invention,
The second temperature may be 130 ° C. or higher and 160 ° C. or lower.

In the method for producing a carbon fiber composite material according to the present invention,
The carbon nanofiber may have an average diameter of 0.5 to 500 nm.

In the method for producing a carbon fiber composite material according to the present invention,
The average particle size of the ultra high molecular weight polyethylene used in the step (a) may be 10 to 200 μm.

In the method for producing a carbon fiber composite material according to the present invention,
The roll space | interval in the open roll of the said process (b) can be set to 0.5 mm or less.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  In the method for producing a carbon fiber composite material according to an embodiment of the present invention, an ultra high molecular weight polyethylene is introduced into an open roll having a roll set at a first temperature and wound around the roll. And mixing the mixture into an open roll having a roll set to a second temperature and passing through the carbon nanofibers by shearing force. And (b), wherein the first temperature is a temperature at which the ultrahigh molecular weight polyethylene melts and winds around the roll of the first step (a), and the second temperature The temperature is higher than

(I) Ultra high molecular weight polyethylene Ultra high molecular weight polyethylene (UHMWPE) is a commercially available particulate ultra high molecular weight polyethylene resin, preferably having an average molecular weight measured by a viscosity method of 1,000,000 g / mol to 8,000,000. g / mol, more preferably 3 million g / mol to 8 million g / mol. The average particle size of the ultra high molecular weight polyethylene is preferably 10 to 200 μm. The ultrahigh molecular weight polyethylene has a melting temperature (melting point) of 130 ° C. to 135 ° C., the flow start temperature at which the ultra high molecular weight polyethylene particles start to fuse with each other is 180 ° C. or higher, and the ultra high molecular weight polyethylene is thermally decomposed. It is preferable that the thermal deterioration starting temperature (thermal decomposition temperature) to be started is 230 ° C. or higher. The melting temperature and flow start temperature of ultra high molecular weight polyethylene can be measured by a thermomechanical analyzer (TMA) described later. Moreover, the thermal degradation start temperature of ultra high molecular weight polyethylene can be measured by the thermogravimetric analysis (TG) method mentioned later. Examples of commercially available ultra high molecular weight polyethylene include Hi-Zex Million from Mitsui Chemicals, Suntech from Asahi Kasei Kogyo, HOSTALRN.GUR from Ticona, and HIFLAX.100 from Hercules.

(II) Carbon nanofibers The carbon nanofibers preferably have an average diameter of 0.5 to 500 nm, and more preferably 0.5 to 160 nm in order to improve the rigidity of the carbon fiber composite material. Furthermore, the carbon nanofibers may be straight fibers or curved fibers. The compounding amount of the carbon nanofiber is not particularly limited and can be set according to the use. However, the carbon nanofiber is 5 parts by weight (phr) to 60 parts by weight (phr) with respect to 100 parts by weight (phr) of ultrahigh molecular weight polyethylene. Is preferable in terms of formability.

  Examples of carbon nanofibers include so-called carbon nanotubes. Carbon nanotubes have a single-layer structure in which graphene sheets with carbon hexagonal mesh surfaces are closed in a cylindrical shape, or a multilayer structure in which these cylindrical structures are arranged in a nested manner. That is, the carbon nanotube may be composed of only a single-layer structure or a multilayer structure, and the single-layer structure and the multilayer structure may be mixed. A carbon material partially having a carbon nanotube structure can also be used. In addition to the name “carbon nanotube”, it may be called “graphite fibril nanotube”.

  Single-walled carbon nanotubes or multi-walled carbon nanotubes are manufactured to a desired size by an arc discharge method, a laser ablation method, a vapor phase growth method, or the like. The arc discharge method is a method of obtaining multi-walled carbon nanotubes deposited on a cathode by performing an arc discharge between electrode materials made of carbon rods in an argon or hydrogen atmosphere at a pressure slightly lower than atmospheric pressure. In addition, the single-walled carbon nanotube is obtained by mixing the carbon rod with a catalyst such as nickel / cobalt to cause arc discharge and adhering to the inner surface of the processing vessel. The laser ablation method melts and evaporates the carbon surface by irradiating a strong YAG laser pulsed laser beam onto a carbon surface mixed with a target catalyst such as nickel / cobalt in a rare gas (eg argon). This is a method for obtaining single-walled carbon nanotubes. The vapor phase growth method is a method in which hydrocarbons such as benzene and toluene are thermally decomposed in the gas phase to synthesize carbon nanotubes. More specifically, a fluid catalyst method, a zeolite supported catalyst method, and the like can be exemplified.

  The carbon nanofibers are subjected to surface treatment such as ion implantation treatment, sputter etching treatment, plasma treatment, etc. in advance before being mixed with ultra high molecular weight polyethylene, thereby improving adhesion and wettability with ultra high molecular weight polyethylene. Can be improved.

(III) Method for Producing Carbon Fiber Composite Material Next, a method for producing a carbon fiber composite material will be described in detail with reference to FIGS. 1 and 2. FIG.1 and FIG.2 is a figure which shows typically the manufacturing method of the carbon fiber composite material by an open roll method.

  As shown in FIG.1 and FIG.2, the open roll 1 has the 1st roll 10 and the 2nd roll 20 which were set to predetermined temperature. The first roll 10 and the second roll 20 are arranged at a predetermined interval d, and rotate in the direction indicated by the arrows in FIGS.

  The method for producing a carbon fiber composite material according to the present embodiment includes a step (a) for obtaining a mixture and a step (b) for obtaining a carbon fiber composite material.

Step (a) will be described with reference to FIG.
In the step (a), first, the open roll 1 having the first roll 10 and the second roll 20 set to the first temperature and set to a predetermined interval d (for example, 1.5 mm) The ultra high molecular weight polyethylene 30 is introduced and wound around the second roll 20. Since the ultrahigh molecular weight polyethylene is not fused even at the melting temperature and remains in the form of particles (powder), the first temperature is the second when the ultrahigh molecular weight polyethylene charged in the open roll 1 is melted. It is the temperature which winds around the roll 20, and is higher than the second temperature in the step (b). The first temperature that satisfies such a condition is preferably, for example, not less than the flow start temperature of the ultrahigh molecular weight polyethylene and less than the heat deterioration start temperature. The flow start temperature can be obtained by measuring a deformation amount with respect to the temperature by applying a constant load while changing the temperature of the ultrahigh molecular weight polyethylene together with the melting temperature by a thermomechanical analyzer (TMA). When thermo-mechanical analysis of ultra-high molecular weight polyethylene is performed in this way, the sample begins to expand rapidly when the melting temperature is exceeded, the expansion of the sample almost stops when the expansion stop temperature is reached, and when the flow start temperature is exceeded, the sample Starts contracting rapidly. The thermal degradation start temperature (thermal decomposition temperature) can be determined as a temperature at which the weight starts to decrease due to thermal decomposition when the weight change of ultrahigh molecular weight polyethylene is measured while the temperature is increased by thermogravimetric analysis (TG). By introducing ultra-high molecular weight polyethylene into the first and second rolls 10 and 20 set to be higher than the flow start temperature and lower than the heat deterioration start temperature, the powdered ultra-high molecular weight polyethylene can be obtained at the melting temperature or higher. However, it is preferable because it can be wound around a roll and mixed with carbon nanofibers. Although 1st temperature changes with kinds of ultra high molecular weight polyethylene, it is preferable that they are 180 degreeC or more and 230 degrees C or less.

  Further, carbon nanofibers 40 are put into a bank 34 of ultrahigh molecular weight polyethylene 30 wound around the second roll 20 and mixed to obtain a mixture 36. The ultra high molecular weight polyethylene 30 wound around the second roll 20 is kneaded at a flow start temperature or higher and less than a thermal degradation start temperature, so that free radicals are generated by appropriately cutting the ultra high molecular weight polyethylene molecular chain. Thus, the carbon nanofibers are easily combined. In the mixture 36, the carbon nanofibers 40 are hardly dispersed.

Step (b) will be described with reference to FIG.
In the step (b), the mixture 36 obtained in the step (a) is put into the open roll 1 having the first and second rolls 10 and 20 set to the second temperature, and is passed through. The carbon nanofibers are dispersed by a shearing force. The second temperature is lower than the first temperature. The roll interval d between the first roll 10 and the second roll 20 is preferably set to 0.5 mm or less, more preferably 0.1 to 0.3 mm, and the mixture 36 is put into the open roll 1. Repeat thinning several times. The number of thinning is preferably about 3 to 10 times. When the surface speed of the first roll 10 is V1 and the surface speed of the second roll 20 is V2, the ratio of the surface speeds (V1 / V2) in thinness is 1.05 to 3.00. Preferably, it is more preferably 1.05 to 1.2. By using such a surface velocity ratio, a desired shear force can be obtained. The carbon fiber composite material obtained through thinning is rolled with a roll and dispensed into a sheet.

  The second temperature in the step (b) is preferably, for example, not less than the melting temperature of the ultrahigh molecular weight polyethylene and less than the flow start temperature, and more preferably not less than the melting temperature and less than the expansion stop temperature. The expansion stop temperature can be measured by the aforementioned thermomechanical analyzer (TMA). Although 2nd temperature changes with kinds of ultra high molecular weight polyethylene, it is preferable that it is 130 to 180 degreeC, for example, and it is more preferable that it is 130 to 160 degreeC. It is preferable that the measured temperature of the ultrahigh molecular weight polyethylene 30 is also adjusted to the second temperature by setting the first and second rolls 10 and 20 to the second temperature. The ultrahigh molecular weight polyethylene at the second temperature has elasticity like an elastomer, and a high shearing force acts on the ultrahigh molecular weight polyethylene 30 by the shearing force due to thinness, and the aggregated carbon nanofibers 40 are superhigh. The molecular weight polyethylene molecules are separated from each other so as to be drawn one by one and dispersed in the ultrahigh molecular weight polyethylene 30.

  More specifically, when ultra high molecular weight polyethylene and carbon nanofibers are mixed with an open roll, viscous ultra high molecular weight polyethylene penetrates into the carbon nanofibers, and free radicals of ultra high molecular weight polyethylene are chemically generated. It binds to the highly active part of the carbon nanofiber by mechanical interaction. Since the surface of the carbon nanofiber is moderately high in activity, it is easy to bind to ultrahigh molecular weight polyethylene molecules. Next, when a strong shearing force acts on the ultrahigh molecular weight polyethylene, the carbon nanofibers move along with the movement of the ultrahigh molecular weight polyethylene molecule, and further aggregate due to the restoring force of the ultrahigh molecular weight polyethylene due to elasticity after shearing. The carbon nanofibers are separated and dispersed in ultra high molecular weight polyethylene. As shown in FIG. 2, when the mixture 36 is pushed out between the narrow first and second rolls 10 and 20, the mixture 36 is deformed to be thicker than the roll interval due to the restoring force due to the elasticity of the ultrahigh molecular weight polyethylene. The deformation is presumed that a carbon fiber composite material in which the carbon nanofibers are uniformly dispersed can be obtained by causing the mixture 36 with a strong shearing force to flow more complicatedly and dispersing the carbon nanofibers in the ultrahigh molecular weight polyethylene. it can. The carbon nanofibers once dispersed are prevented from reaggregating due to chemical interaction with the ultrahigh molecular weight polyethylene, and can have good dispersion stability.

  The carbon fiber composite material may remain in the form of a sheet obtained by the open roll method, or a molding process in which the carbon fiber composite material obtained in the step (b) is generally employed, such as an extrusion molding method, a transfer molding method, You may shape | mold in desired shape, for example, a sheet form, by the injection molding method, the press molding method, etc.

(IV) Carbon fiber composite material A carbon fiber composite material will be described.
In the carbon fiber composite material obtained by the production method, carbon nanofibers are uniformly dispersed in a matrix of ultrahigh molecular weight polyethylene. The carbon fiber composite material obtained by the above production method contains 5 to 60 parts by weight (phr) of carbon nanofibers with respect to 100 parts by weight (phr) of ultrahigh molecular weight polyethylene, and the Hahn-echo method using pulsed NMR Thus, the characteristic relaxation time (T2′H / 150 ° C.) measured at 150 ° C. and the observation nucleus at ¹ H can be 1000 to 4300 μsec. Further, the carbon fiber composite material obtained by the production method described above has a characteristic relaxation time (T2′Hpe / T2′Hpe / measured at 150 ° C. by a Hahn echo method using pulsed NMR in ultrahigh molecular weight polyethylene alone and an observation nucleus of ¹ H. The ratio ((T2′Hpe−T2′H) / T2′Hpe) in which the characteristic relaxation time (T2′H / 150 ° C.) of the carbon fiber composite material has decreased with respect to the carbon fiber composite material is It is preferably 0.5% or more per part by weight. Note that “H” in the characteristic relaxation time (T2′H) is a notation used to distinguish it from “S” in the solid echo method described later, and “pe” of the characteristic relaxation time (T2′Hpe / 150 ° C.). "Indicates ultra-high molecular weight polyethylene alone. The characteristic relaxation time (T2′Hpe / 150 ° C.) of the ultrahigh molecular weight polyethylene is the measurement result of the sheet-like material as in the step (a). This is because the molecular weight is lowered by the step (a) as compared with the powdery raw material of ultrahigh molecular weight polyethylene, and the characteristic relaxation time is also reduced.

The characteristic relaxation time (T2′H) by the Hahn-echo method is a scale indicating the molecular mobility of ultrahigh molecular weight polyethylene, and represents the average relaxation time of a multicomponent system. Therefore, the characteristic relaxation time (T2′H) is an average value of a plurality of relaxation times detected by the Hahn echo method.
1 / T2′H = fa / T2a + fb / T2b + fc / T2c...
It can be expressed as.

  The carbon fiber composite material in which the carbon nanofibers are dispersed represents the force that the carbon nanofibers restrain the ultra-high molecular weight polyethylene molecules as the matrix, and the characteristic relaxation time (T2′H / 150 ° C.) by the Hahn echo method at 150 ° C. ) Becomes smaller depending on the blending amount of the carbon nanofibers than the characteristic relaxation time (T2′Hpe / 150 ° C.) of the ultrahigh molecular weight polyethylene alone. Therefore, even in the case of a carbon fiber composite material in which carbon nanofibers are mixed, if the carbon nanofibers are not uniformly dispersed, it is difficult to restrain the ultrahigh molecular weight polyethylene molecules as a whole. The characteristic relaxation time (T2′H / 150 ° C.) is almost the same as the characteristic relaxation time (T2′Hpe / 150 ° C.) of the ultra-high molecular weight polyethylene alone, for example, the ratio of the characteristic relaxation time (T2′H / 150 ° C.) being reduced. Is less than 0.5% or increased.

The carbon fiber composite material obtained by the production method includes 5 to 60 parts by weight of carbon nanofibers with respect to 100 parts by weight of ultrahigh molecular weight polyethylene, and 150 ° C. by solid echo method using pulsed NMR. The characteristic relaxation time (T2 ′S / 150 ° C.) measured by the observation nucleus at ¹ H can be 4 to 1000 μsec. Further, the carbon fiber composite material obtained by the above production method has a characteristic relaxation time (T2′Spe / T) measured at 150 ° C. by a solid echo method using an ultrahigh molecular weight polyethylene alone at 150 ° C. with an observation nucleus of ¹ H. The ratio ((T2′Spe−T2 ′S) / T2′Spe) in which the characteristic relaxation time (T2 ′S / 150 ° C.) of the carbon fiber composite material has decreased with respect to (150 ° C.) It is preferably 1.0% or more per part by weight.

The characteristic relaxation time (T2 ′S) by the solid echo method is a scale indicating the magnetic field inhomogeneity due to the carbon nanofibers, and represents the average relaxation time of a multicomponent system. Therefore, the characteristic relaxation time (T2 ′S) is an average value of a plurality of relaxation times detected by the Hahn echo method.
1 / T2'S = fa / T2a + fb / T2b + fc / T2c
It can be expressed as.

  Carbon fiber composites with dispersed carbon nanofibers cause magnetic field non-uniformity due to the uniform dispersion of carbon nanofibers, and the characteristic relaxation time (T2'S / 150 ° C) by the solid echo method at 150 ° C is excessive. It becomes small according to the compounding quantity of carbon nanofiber compared with the characteristic relaxation time (T2′Spe / 150 ° C.) of high molecular weight polyethylene alone. In addition, even when carbon nanofibers are mixed with carbon nanofibers, non-uniformity of the magnetic field is not introduced when carbon nanofibers are not uniformly dispersed. The relaxation time (T2 ′S / 150 ° C.) is almost the same as the characteristic relaxation time (T2′Spe / 150 ° C.) of the ultra-high molecular weight polyethylene alone. Less than 1%.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

(1) Measurement of Ultra High Molecular Weight Polyethylene with Thermomechanical Analyzer (TMA) Ultra High Molecular Weight Polyethylene (UHMWPE) is a particulate high molecular weight polyethylene resin made by Mitsui Chemicals Co., Ltd., and measured by the viscosity method. An average molecular weight of 5.5 million g / mol was used. Particulate ultra high molecular weight polyethylene is sandwiched between quartz plates (0.5 g) to prevent fusion, and is compressed into a sheet of approximately 1 mm thickness, and compressed with a thermomechanical analyzer (TMA) with a substantial load of +0.5 g. Then, the amount of thermal deformation (μm) with respect to temperature change was measured. The measuring apparatus used was TMA / SS6100 manufactured by SII. The measurement results are shown in FIG.

  According to the measurement result of FIG. 3, the ultrahigh molecular weight polyethylene used in this example has an expansion coefficient at point A, an expansion coefficient further rapidly at point B, and almost no expansion at point C. At point D, sudden contraction started. From these results, point A is a glass transition point of about 60 ° C., point B is a melting temperature of about 130 ° C., point C is an expansion stop temperature of about 160 ° C., and point D is a flow start temperature of about 180 ° C. I understood. For point B, the melting temperature was confirmed by differential scanning calorimetry (DSC).

(2) Production of carbon fiber composite material samples of Examples 1 to 5 and Comparative Examples 1 to 3 Step (a): 6-inch open roll (roll temperature 210 ° C., roll interval 1.5 mm) as shown in Table 1 A fixed amount of ultrahigh molecular weight polyethylene (100 parts by weight (phr)) was charged and wound around a roll, and then the amount of carbon nanofibers shown in Table 1 was charged, and the mixture was taken out from the open roll.

  Step (b): A 6-inch open roll (roll temperature 150 ° C., roll interval 0.1 mm) is charged with the mixture obtained in step (a), and thinning is repeated three times to obtain a carbon fiber composite material. Obtained. At this time, the surface speed ratio of the two rolls was set to 1.1. Furthermore, the carbon fiber composite material obtained by setting the roll gap to 1.1 mm and passing through was put and dispensed.

The dispensed carbon fiber composite material was press-molded at 220 ° C. for 5 minutes with preheating for 3 minutes under pressure, and formed into a sheet-like carbon fiber composite material with a thickness of 1 mm.
The sample of Comparative Example 1 is an ultra-high molecular weight polyethylene alone, but it is put into an open roll under the same conditions as in step (a), dispensed into a sheet, and further heated at 220 ° C. for 5 minutes. It was press-molded at a pressure of 3 minutes to form a sheet-like sample having a thickness of 1 mm.

  In Table 1, “UHMWPE” of the ultra-high molecular weight polyethylene as a raw material has an average molecular weight of about 5.5 million g / mol as measured by the viscosity method of the Hi-Zex Million manufactured by Mitsui Chemicals. The molecular weight is about 50,000 g / mol. In Table 1, “vapor-grown carbon fibers” are multi-wall carbon nanotubes manufactured by a vapor-phase growth method having an average diameter of 87 nm and an average length of 10 μm, and “CNT 13” is an ILJIN-made average diameter of 13 nm. It is a multi-wall carbon nanotube (CVD method).

(3) Measurement using pulse method NMR The carbon fiber composite material samples of Examples 1 to 5 and Comparative Examples 1 and 3 were measured by the Hahn echo method using pulse method NMR. This measurement was performed using “JMN-MU25” manufactured by JEOL Ltd. The measurement is carried out under the conditions of the observation nucleus of ¹ H, the resonance frequency of 25 MHz, and the 90 ° pulse width of 2 μsec. The attenuation curve is measured by the pulse sequence of the Hahn-echo method (90 ° x-Pi-180 ° y). The characteristic relaxation time (T2′H) at 150 ° C. of the carbon fiber composite material sample was measured. The measurement results are shown in Table 1.

  Furthermore, the carbon fibers of Examples 1 to 5 with respect to the characteristic relaxation time (T2′Hpe / 150 ° C.) measured in the same manner by the Hahn echo method using pulsed NMR in the ultrahigh molecular weight polyethylene alone of Comparative Example 1 The ratio ((T2′Hpe−T2′H) / T2′Hpe) in which the characteristic relaxation time (T2′H / 150 ° C.) of the composite material decreased was calculated per 1 part by weight of the carbon nanofiber. For example, in the case of Example 1, it was calculated as (4570 μsec-4200 μsec) / 4570 μsec / 5 phr × 100 = 1.619%. The calculation result is shown in “T2′H decrease rate” in Table 1. The raw material powdery ultrahigh molecular weight polyethylene had a characteristic relaxation time (T2′H) of 4650 μsec, and the general-purpose polyethylene had a characteristic relaxation time (T2′H) of 6390 μsec.

Moreover, the measurement by the solid echo method was performed using pulse method NMR. This measurement was performed using “JMN-MU25” manufactured by JEOL Ltd. The measurement is carried out under the conditions of the observation nucleus of ¹ H, the resonance frequency of 25 MHz, and the 90 ° pulse width of 2 μsec. The attenuation curve is measured by the pulse sequence of solid echo method (90 ° x-Pi-90 ° y). The characteristic relaxation time (T2 ′S) at 150 ° C. of the carbon fiber composite material sample was detected. The measurement results are shown in Table 1.

  Further, the carbon fibers of Examples 1 to 5 with respect to the characteristic relaxation time (T2′Spe / 150 ° C.) measured in the same manner by the solid echo method using the pulse method NMR in the ultrahigh molecular weight polyethylene alone of Comparative Example 1. The ratio ((T2′Spe−T2 ′S) / T2′Spe) in which the characteristic relaxation time (T2 ′S / 150 ° C.) of the composite material decreased was calculated per 1 part by weight of the carbon nanofibers. For example, in the case of Example 1, it was calculated as (1580 μsec−940 μsec) / 1580 μsec / 5 phr × 100 = 8.101%. The calculation results are shown in “T2 ′S reduction rate” in Table 1.

(4) Measurement of tensile strength (TB) and elongation at break (EB) About a test piece obtained by cutting a carbon fiber composite material sample into a 1A-type dumbbell shape, 23 ± 2 using a tensile tester manufactured by Toyo Seiki Co., Ltd. A tensile test was performed based on JIS K6251 at a temperature of 5 ° C. and a tensile speed of 500 mm / min, and the tensile strength (MPa) and elongation at break (%) were measured. These results are shown in Table 1.

  Moreover, the electron microscope (SEM) photograph of the tensile fracture surface of the carbon fiber composite material sample of Example 4 is shown in FIG. 4 (3.0 kV, 50 times), FIG. 5 (3.0 kV, 20,000 times), and FIG. 3 (3.0 kV, 50,000 times), and FIG. 7 (3.0 kV, 100 times) and FIG. 8 (3.0 kV) are the electron microscope (SEM) photographs of the tensile fracture surface of the carbon fiber composite material sample of Example 5. 10,000 times), FIG. 9 (3.0 kV, 30,000 times), and FIG. 10 (3.0 kV, 100,000 times).

(5) Dynamic Viscoelasticity Test A test piece obtained by cutting a carbon fiber composite material sample into a strip (40 × 1 × 5 (width) mm) was chucked using a dynamic viscoelasticity tester DMS6100 manufactured by SII. A dynamic viscoelasticity test is performed based on JIS K6394 at a distance of 20 mm, a measurement temperature of −100 to 300 ° C., a dynamic strain of ± 0.05%, and a frequency of 10 Hz, and a dynamic elastic modulus (E ′, unit is MPa) is measured. did. Table 1 shows the measurement results of the dynamic elastic modulus (E ′) at the measurement temperatures of 30 ° C. and 200 ° C.

(6) Measurement of deformation start temperature A dimensional change of a carbon fiber composite material sample having a thickness of about 1 mm was measured by a thermomechanical analyzer (TMA) with no load. And the temperature which starts the big deformation | transformation by melting was made into the deformation | transformation start temperature. The measuring apparatus used was TMA / SS6100 manufactured by SII. The results are shown in Table 1. In Table 1, the case where no significant deformation was observed at (measured temperature range unknown) -100 ° C. to 300 ° C. was described as “none”.

(7) Measurement of thermal degradation start temperature (thermal decomposition temperature) When carbon fiber composite material samples were measured for weight change while being heated at a temperature rising rate of 20 ° C./min by thermogravimetric analysis (TG) method, As a result, the temperature at which the weight starts to decrease was obtained as the thermal deterioration start temperature. The measuring device used was TG / DTA6300 manufactured by SII. The results are shown in Table 1. The starting temperature of thermal degradation of the raw material ultra-high molecular weight polyethylene alone was 333 ° C.

From Table 1, according to Examples 1 to 5 of the present invention, the following was confirmed. That is, the carbon fiber composite materials of Examples 1 to 5 of the present invention have a characteristic relaxation time (T2′H / 150 ° C.) shorter than that of Comparative Examples 1 and 3 and 2300 to 4200 μsec. The reduction rate of the characteristic relaxation time (T2′H / 150 ° C.) was 0.5% or more as compared with the ultrahigh molecular weight polyethylene simple substance sample. In addition, the carbon fiber composite materials of Examples 1 to 5 of the present invention have a shorter characteristic relaxation time (T2 ′S / 150 ° C.) than those of Comparative Examples 1 and 3 and are 150 to 1000 μsec. The decrease rate of the characteristic relaxation time (T2 ′S / 150 ° C.) was 1.0% or more compared to the ultrahigh molecular weight polyethylene simple substance sample. Moreover, since the carbon fiber composite material of Examples 1-5 of this invention improved the dynamic viscoelastic modulus (E '), it was speculated that rigidity improved and abrasion resistance also improved. In the carbon fiber composite materials of Examples 2 to 5, it was found that no deformation start temperature was observed even at a temperature equal to or higher than the melting temperature of ultrahigh molecular weight polyethylene, and extremely high heat resistance was exhibited. Thus, it was speculated that the improved heat resistance improves the wear resistance due to adhesive wear particularly at high temperatures. In Comparative Example 2, the amount of carbon nanofibers was too large to be molded. The fracture surfaces of the carbon fiber composite materials of Examples 4 and 5 of the present invention are highly uniform in macro view without the non-uniformity such as the sea-island structure as shown in FIGS. As shown in FIGS. 7 and 7, it can be seen that the carbon nanofibers are highly uniform even when viewed microscopically. Also, according to FIGS. 6, 9, and 10, it can be seen that the interface between the carbon nanofibers and the ultrahigh molecular weight polyethylene in the fracture surface of the carbon fiber composite material of Examples 4 and 5 of the present invention is well wetted. In FIG. 9, it was found that the ductility is high because the dimples are broken.

It is a figure which shows typically the process (a) by an open roll method. It is a figure which shows typically the process (b) by an open roll method. It is a graph which shows the temperature change-thermal deformation amount measured with the thermomechanical analyzer (TMA). It is an electron micrograph of the tensile fracture surface of the carbon fiber composite material sample of Example 4 (photographing conditions: 3.0 kV, 50 times). It is an electron micrograph of the tensile fracture surface of the carbon fiber composite material sample of Example 4 (imaging conditions: 3.0 kV, 20,000 times). It is an electron micrograph (photographing conditions: 3.0 kV, 50,000 times) of the tensile fracture surface of the carbon fiber composite material sample of Example 4. It is an electron micrograph (photographing conditions: 3.0 kV, 100 times) of the tensile fracture surface of the carbon fiber composite material sample of Example 5. It is an electron micrograph (photographing conditions: 3.0 kV, 10,000 times) of the tensile fracture surface of the carbon fiber composite material sample of Example 5. It is an electron micrograph (photographing conditions: 3.0 kV, 30,000 times) of the tensile fracture surface of the carbon fiber composite material sample of Example 5. It is an electron micrograph (photographing conditions: 3.0 kV, 100,000 times) of the tensile fracture surface of the carbon fiber composite material sample of Example 5.

DESCRIPTION OF SYMBOLS 10 1st roll 20 2nd roll 30 Ultra high molecular weight polyethylene 40 Carbon nanofiber d Roll space | interval V1 Surface speed V2 of 1st roll Surface speed of 2nd roll

Claims (7)

Step (a) in which an ultra high molecular weight polyethylene is introduced into an open roll having a roll set at a first temperature and wound around the roll, and further carbon nanofibers are added and mixed to obtain a mixture;
(B) disperse | distributing the said carbon nanofiber with a shearing force by throwing the said mixture into the open roll which has a roll set to 2nd temperature, and making it pass through thinly.
Including
The first temperature is a temperature at which the ultrahigh molecular weight polyethylene is melted and wound around the roll in the first step (a), and is higher than the second temperature. Production method. In claim 1,
The first temperature is equal to or higher than the flow start temperature of the ultra high molecular weight polyethylene and lower than the heat deterioration start temperature,
The method for producing a carbon fiber composite material, wherein the second temperature is equal to or higher than a melting temperature of the ultrahigh molecular weight polyethylene and lower than a flow start temperature. In claim 1 or 2,
The first temperature is 180 ° C. or higher and 230 ° C. or lower,
The method for producing a carbon fiber composite material, wherein the second temperature is 130 ° C. or higher and lower than 180 ° C. In any of claims 1 to 3,
The method for producing a carbon fiber composite material, wherein the second temperature is 130 ° C. or higher and 160 ° C. or lower. In any of claims 1 to 4,
The carbon nanofiber is a method for producing a carbon fiber composite material having an average diameter of 0.5 to 500 nm. In any of claims 1 to 5,
The manufacturing method of the carbon fiber composite material whose average particle diameter of the ultra high molecular weight polyethylene used for the said process (a) is 10-200 micrometers. In any one of Claims 1 thru | or 6.
The method for producing a carbon fiber composite material, wherein a roll interval in the open roll of the step (b) is set to 0.5 mm or less.