JP3008095B1 - Method for producing flaky porous carbon material - Google Patents

Abstract

The object of the present invention is to provide a porous carbon material which is hard, has less cracks and irregularities, and retains the porous structure of raw wood. The present invention provides a method for producing a flaky porous carbon material, which comprises impregnating a pulp raw material with a thermosetting resin, molding under pressure in a non-oxidizing atmosphere, and firing and carbonizing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electrode substrate, for example,
Humidifier, diaphragm, heater, activated carbon, electromagnetic shielding material,
The present invention relates to a method for manufacturing a flaky porous carbon material used for a synchronizer ring, a clutch plate, a friction material, a bearing material, a humidity sensor, a temperature sensor, a filter material, a heat insulating material, a gas adsorbent, a brake material, a craft, a studless tire, and the like. .

[0002]

2. Description of the Related Art Conventionally, methods of carbonizing wood are roughly classified into a coal making method of carbonizing while sending air from an air vent, and a dry distillation method of carbonizing in a completely closed system. Aims to obtain wood vinegar and wood tar. In the coal production method, carbonization is performed while sending air, so that carbonization under uniform conditions is difficult, and the coal yield is low. And the quality of the obtained product is greatly affected by the raw material tree species, moisture, etc., and it is apt to be broken or disordered, so it is only used as a fuel or an adsorbent, and various industrial uses as a carbon material Was unsuitable for Therefore, the present inventor previously conducted various studies to improve this disadvantage, and as a result, using wood or bamboo as a raw material, impregnating these cut pieces or crushed pieces with a phenolic resin, curing, and then carbonizing at a high temperature. It is harder, less cracked and less distorted, leaving the porous structure of raw wood or bamboo, and has the potential to be used for applications such as current-carrying materials, electromagnetic shielding materials in electronic equipment, aerospace materials, nuclear materials, etc. Hard carbon products were announced under the name of wood ceramics or bamboo ceramics (for the former, see Patent No. 25552577, and for the latter, see "BOUNDARY" issued in February 1997).

However, the hard carbon obtained by these methods has a large shrinkage in the thickness direction during the firing carbonization process, reaching about 50%. Therefore, it is difficult to directly produce a porous carbon material requiring dimensional accuracy, and post-processing has been required. In addition, the thin porous carbon material becomes expensive due to the post-processing, and not only the purpose of use is restricted, but also when a flake-like material is required, a device such as processing from a thick material is required.

[0004]

The present inventor has conducted various studies to improve the above-mentioned drawbacks and to obtain a low-cost, flaky, and strong porous carbon material. It has been found that the pulp state is used, and the use of the pulp as a raw material significantly improves the pulp state. Especially for bamboo,
The bamboo pulp widely used as calligraphy washi was found to be extremely promising as a material for the porous carbon material, and was further studied to complete the present invention. It is an object of the present invention to provide a method for producing a carbonaceous material.

[0005]

The gist of the present invention is to provide a bamboo chip.
The bamboo pulp obtained by pulverizing the fiber into a fiber is impregnated with a thermosetting resin, which is calcined and carbonized while being pressed under a non-oxidizing atmosphere. Oh Ru.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail.
The pulp raw material used in the present invention is bamboo pulp. Bamboo pulp is obtained by pulverizing bamboo chips into fibers by various methods. The fiberization methods include (a) batting and papermaking of bamboo chips, and (b) sifting bamboo chips. , Fibrillation, and (c) steaming the bamboo chips and refining the bamboo chips, etc., but any of these methods may be used. When the obtained bamboo pulp is compared with other softwood pulp and hardwood pulp in terms of fiber size and water absorption, the results shown in Tables 1 and 2 are obtained. In addition,
The water absorption test was performed under the conditions of a dry bulb temperature of 20 ° C and a wet bulb temperature of 35 ° C.

[0007]

[Table 1]

[0008]

[Table 2]

That is, bamboo pulp has the largest fiber length and fiber width relative to the fiber length and is rich in toughness, and bamboo pulp has the highest water absorption among pulp raw materials. Good. From these points, bamboo pulp is most suitable as a raw material for producing the flaky porous carbon material of the present invention. Next, the impregnation ratio of each pulp raw material and resin is shown. The measuring method of the impregnation rate is 10 cm × 10 2 for each pulp raw material (bamboo pulp, hardwood pulp, softwood pulp).
The phenol resin was impregnated with the phenol resin for 4 hours under the conditions of an oscillation output of 400 W and a reduced pressure of -760 mmHg by using an ultrasonic resin impregnating apparatus to cm × 0.8 mm. Table 3 shows the results. Bamboo pulp impregnation rate of 182%, hardwood pulp impregnation rate of 94.6%, softwood pulp impregnation rate of 88.8%
% Order. Under the same conditions, the impregnated rate of the raw fiberboard generally used as wood ceramics is about 50%, and the pulp raw material has higher impregnation and workability, and bamboo pulp is particularly excellent. It has characteristics.

[0010]

[Table 3]

With respect to bamboo, the impregnation ratio of phenolic resin between a fiber plate made of cut or crushed pieces of bamboo and bamboo paper obtained from pulp fibers obtained by defibrating bamboo fibers was compared as follows. The result was obtained. Using cut pieces or crushed pieces of Moso bamboo, 100mm × 42mm × 6-1
A fiberboard having a size of 0 mm was prepared, and this was a phenol resin (P
X-1600), and a reduced pressure impregnation method of impregnating under reduced pressure, the value was about 10% at the maximum even when the impregnation time was changed (half day to several days). Was. However, the time to soak in the phenol resin is 1, 2
After about a month, an impregnation of about 20% was obtained. This result was almost the same regardless of whether the natural impregnation method or the vacuum impregnation method was used. The impregnation conditions in the vacuum impregnation method were as follows. Vacuum container used: Cylindrical vacuum container having a diameter of 140 mm and a height of 200 mm Evacuation speed: Evacuation speed 15 liter / min Background vacuum degree 1 Torr On the other hand, bamboo paper having a size of 50 mm x 50 mm x 1 mm was used as bamboo pulp and naturally impregnated. When the phenolic resin was impregnated by a vacuum method and a vacuum impregnation method, good results were obtained in both impregnation methods. Regardless of the impregnation time, the impregnation rate is about 20% larger in the vacuum impregnation method than in the natural impregnation method.
Results greater than 0% were obtained. The impregnation conditions of the vacuum impregnation method were the same as those described above. FIG. 1 shows the measurement results of the impregnation rate with respect to the impregnation time by the natural impregnation method and the vacuum impregnation method.

In the production method of the present invention, pulp is first impregnated with a thermosetting resin. The raw material pulp is obtained by a known method as in the case of the bamboo pulp described above. Any thermosetting resin that can be used for impregnation may be a phenol resin, a furan resin, a urea resin, or the like. The impregnation means is no different from the conventional wood ceramics method,
For example, the pulp material is impregnated with the pulp material at a rate of 30 to 80% by weight by injecting under reduced pressure with a vacuum pump. When bamboo pulp is used as the pulp, the phenol resin is most preferable because the phenol resin has excellent properties such as permeability with respect to the bamboo pulp. Pulp raw material impregnated with thermosetting resin under non-oxidizing atmosphere,
It is pressed and fired and carbonized. As the pressure forming means, the material is clamped and clamped between the upper and lower platens. The pressing condition is 0 to 0.4 kgf. It was baked at 2000 ° C. The firing is preferably performed while rotating to uniformly heat.

FIG. 2 shows an example of a firing apparatus used in the present invention. In FIG. 2, a processing product 2 impregnated with a resin is placed in a central portion of a furnace body 1, and a pressing device 3 for pressing the processing product 2 is provided at an upper portion of the furnace. Drain tank 4 at the bottom of the furnace
And connected to the adjacent cooling device 5 by a pipe 6, and further through an intermediate tank 7 to a water ring pump 8 to discharge volatiles from the treated product to the outside of the furnace. In such an apparatus, the processed product is stored in a furnace, and the processed product 2 is pressurized by the pressing device 3. At this time, the processed product may be rotated. The furnace body 1 is energized and heated. The heating of the furnace body is controlled by a power control panel and a control panel. Liquid volatiles generated in the furnace as the furnace body is heated are collected in a drain tank 4, and the volatiles enter a cooler 5 via a pipe 6. Here, the volatile matter vaporized in the furnace is liquefied to lower the discharge temperature. Subsequently, the intermediate tank 7 receives the liquid volatiles flowing to the discharge side, and the water ring pump 8 operates in conjunction with a vacuum gauge and an exhaust valve to maintain a constant degree of vacuum, and retains the volatiles from the processed product in the furnace. Exhaust without letting go.

The obtained product has a large coefficient of friction, including electrode substrates, heaters, humidity sensors, temperature sensors, filters, etc., which are the original uses of carbon materials, and is used for clutch plates, bearing materials, etc. Because of its excellent vibration characteristics, it is possible to manufacture excellent products in a wide range of fields, such as where the use of acoustic equipment is considered.

[0015]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 A bamboo pulp having a length of 10 cm, a width of 10 cm and a thickness of 0.8 mm is impregnated with about 80% of a phenolic resin, and is sandwiched between magnetic plates having a length of 15 cm and a thickness of 6 mm in a charcoal furnace.
Molding pressure (clamping pressure) by adding 304 stainless steel weight
At a temperature of 800 ° C. with a temperature rising rate of 5 ° C./min.
The sintering was performed while rotating for a period of time. Table 4 shows the value of the maximum height of warpage (mm) with respect to the molding pressure of the obtained porous carbon material and the state of crack generation. With the measurement method of warpage, place the obtained flaky porous carbon material on a flat surface plate,
The maximum height (mm) of the portion away from the surface plate due to the warpage at that time was measured. As can be seen from Table 4, if the molding pressure is high, cracks occur, and the low molding pressure is 0.10 kgf / cm ^2.
In the following, a thin porous carbon material without cracks and without warpage was obtained, and the lower the molding pressure, the better.

[0016]

[Table 4]

Example 2 A bamboo pulp having a length of 10 cm, a width of 10 cm and a thickness of 0.8 mm is impregnated with about 80% of a phenol resin, and is sandwiched between magnetic plates having a length of 15 cm and a thickness of 6 mm in a charcoal furnace. SUS on top
Forming pressure (pressing pressure) by adding 304 stainless steel weight
400 ° C., 500 ° C. under the condition of a temperature rising rate of 5 ° C./min.
C., 600.degree. C., 700.degree. C., and 800.degree. Table 5 shows the dimensional reduction rate and weight reduction rate of the obtained porous carbon material for each firing time.

[0018]

[Table 5]

Example 3 Bamboo pulp having a length of 10 cm, a width of 10 cm and a thickness of 0.8 mm was impregnated with about 80% of a phenol resin, and was sandwiched between magnetic plates having a length of 15 cm and a thickness of 6 mm in a charcoal furnace. SUS on top
Forming pressure (pressing pressure) by adding 304 stainless steel weight
400 ° C., 500 ° C. under the condition of a temperature rising rate of 5 ° C./min.
℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃, 1,6
Firing was performed at a temperature of 00 ° C. and 2,000 ° C. for 3 hours. Table 6 shows the electrical resistivity of the obtained porous carbon material.

[0020]

[Table 6]

Example 4 A bamboo pulp having a length of 10 cm, a width of 10 cm and a thickness of 0.8 mm was impregnated with about 80% of a phenol resin, and was sandwiched between magnetic plates of 15 cm in length and 6 mm in thickness in a charcoal furnace. SUS on top
304 stainless steel weight (0.01 kgf / cm ² )
Was added as a molding pressure (compression pressure), and calcination was performed at a temperature of 800 ° C. for 3 hours at a rate of temperature increase of 5 ° C./min. The electric field shielding properties and the magnetic field shielding properties of the obtained porous carbon material are shown in FIGS.

Example 5 A bamboo pulp and a hardwood pulp having a length of 10 cm, a width of 10 cm and a thickness of 0.8 mm were impregnated with 80% of a phenolic resin, and then were placed in a charcoal furnace having a non-oxygen atmosphere inside the furnace. Each of the flaky porous carbon materials was obtained by firing while rotating under the conditions shown in (1). The resulting flaky porous carbon materials (hardwood-800 and bamboo-800, respectively) were subjected to a friction test using a reciprocating friction tester. The reciprocating friction tester consists of a friction pair between an upper ball test piece and a lower flat plate test piece. Alumina oxide was used for the upper spherical test piece, and the flaky porous carbon material obtained as the lower flat plate test piece was used. The test conditions were as follows: load: 0.098 to 0.98 (N), sliding speed: 10 mm / sec, stroke: 5 mm, lubrication in the air at 40 times, lubrication in the atmosphere, base oil impregnation, and underwater conditions. The results obtained are as follows. Atmosphere-free lubrication condition Test material Friction coefficient μ Hardwood-800 0.13 to 0.20 Bamboo-800 0.13 to 0.19 Base oil impregnation condition Test material Friction coefficient μ Hardwood-800 0.13 to 0. 19 Bamboo-800 0.13 ~ 0.18 Underwater condition Test material Friction coefficient μ Hardwood-800 0.13 ~ 0.22 Bamboo-800 0.13 ~ 0.18 Based on the above results, without lubrication in the atmosphere, and It can be seen that the combination of the flaky porous carbon material and alumina oxide has a very low friction coefficient and is stable under the water condition as in the base oil impregnation condition.

Example 6 A bamboo pulp having a length of 10 cm, a width of 10 cm and a thickness of 0.8 mm was impregnated with 50% of a phenolic resin, and then, as shown in Example 1 in a charcoal furnace having a non-oxygen atmosphere inside the furnace. The flakes were fired while rotating under the conditions to obtain a flaky porous carbon material. When the temperature dependence of the electrical resistivity of the obtained flaky porous carbon material was examined, the following results were obtained. Temperature ℃ 50 100 150 200 250 300 350 400 Electrical resistivity (Ω ・ cm) 0.33 0.30 0.27 0.24 0.20 0.18 0.17 0.16

Example 7 The performance as a humidity sensor was examined. Bamboo pulp impregnated with 50% phenolic resin and baked at 650 ° C
10mm (length) x 10mm (width) x 0.5mm (thickness)
To prepare a sample flaky porous carbon material. The electric resistance was measured by a terminal method using a digital multimeter, and the relative humidity was measured using an Amman ventilation psychrometer. The results are shown below. Electric resistance is relative humidity 4
The value when increasing from 4% to 82% and the value when decreasing from 82% to 44%. Relative humidity (%) 44 47 51 54 58 62 65 Electrical resistance (kΩ) Increase 0.759 0.756 0.754 0.754 0.752 0.751 0.749 Decrease 0.757 0.756 0.754 0.753 0.752 0.750 0.749 70 74 77 77 82 0.747 0.746 0.745 0.744 0.749 0.746 0.745 0.745 When it is between 85% and 85%, the linearity is good and the hysteresis is relatively small. Also, the rate of change of the electric resistance value was as large as 2% per 10% humidity.

Example 8 The bamboo pulp obtained in Example 7 was analyzed by an infrared radiation measuring apparatus (JIR-E500, manufactured by JEOL Ltd.).
Spectral emission intensity was measured in the range of ２２22 μm. The spectral radiation intensity when the flaky porous carbon material was heated to 240 ° C. was compared with blackbody radiation at the same temperature. The results are shown in FIG. The spectral radiant intensity has a peak around 5 μm, has a characteristic of gradually decreasing to a long wavelength, and has a radiation characteristic similar to that of a black body.

Example 9 A bamboo pulp and a hardwood pulp having a length of 10 cm, a width of 10 cm and a thickness of 1 mm were impregnated with 50% of a phenol resin, and then fired at 650 ° C. in a charcoal furnace having a non-oxygen atmosphere. A flaky porous carbon material was produced. At that time, A at the four corners in the furnace,
Samples were placed at positions B, C, D and a central portion E in the furnace, and the electrical resistivity of the flaky porous carbon material obtained in the case of firing while rotating and in the case of firing without rotating was measured. . The results are shown below. Electric resistivity measurement point ABCDE No rotation (Ω · cm) 160 125 240 250 360 Rotation (Ω · cm) 120 125 115 118 120 When the result is rotated, the electric resistivity is small and carbonization is rapid. Indicates progress.

[0027]

As described above, according to the present invention, the pulp raw material is impregnated with the thermosetting resin, and is molded under pressure in a non-oxidizing atmosphere to suppress shrinkage in the thickness direction. Carbonization was possible while maintaining dimensional stability with little deviation, and the obtained porous carbon material could be made into a flake-like product having strength.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between impregnation time and impregnation rate for bamboo pulp.

FIG. 2 shows an example of an in-use firing apparatus according to the present invention.

FIG. 3 is an electric field shielding characteristic of the flaky porous carbon material obtained by the present invention.

FIG. 4 shows the magnetic field shielding properties of the flaky porous carbon material obtained by the present invention.

FIG. 5 shows the infrared intensity of the flaky porous carbon material obtained in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Furnace body 2 Processed product 3 Pressing device 4
Drain tank 5 Cooling device 6 Pipe 7 Intermediate tank
8 Water ring pump

Claims (1)

(57) [Claims] 1. A bamboo pulp <br/> the bamboo chips obtained by crushing the fibers of the thermosetting resin impregnated into, which in a non-oxidizing atmosphere,
A method for producing a flaky porous carbon material, comprising calcining and carbonizing while pressing.