JP2005350307A - Modified carbon material and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a modified carbon material which can be easily subjected to hydrophilic treatment in a short period of time without using chemicals, and a method for manufacturing the same. <P>SOLUTION: The modified carbon material is obtained by irradiating a carbon material with microwaves. The method of manufacturing the modified carbon material includes a process for forming the carbon material by firing a polymer material of natural origin having atomic groups containing a heteroatom such as nitrogen, oxygen or sulfur in the main chain or the side chain at 500-1,000°C under an inert gas atmosphere and a process for irradiating the carbon material with microwaves. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a modified carbon material having hydrophilicity and a method for producing the same.

Conventionally, in order to impart hydrophilicity to a carbon material, a method of forming a hydrophilic polymer film on the surface of the carbon material, a method of vapor phase oxidation or liquid phase oxidation of the carbon material, and the like have been taken.
JP-A-6-166554 JP 2003-213563 A

However, the method of forming a hydrophilic polymer film on the surface may lose the properties originally possessed by the carbon material, such as affinity with a living body.
In addition, the vapor phase oxidation method requires processing at a high temperature, so that power consumption increases, and it takes time to raise and lower the temperature, resulting in poor processing efficiency. In the liquid phase oxidation method, since a strong oxidizing agent is used, workability is deteriorated and processing efficiency is still poor.
The present invention has been made to solve the above problems, and its object is to
An object of the present invention is to provide a modified carbon material and a method for producing the same, which can perform hydrophilic treatment in a short time and easily without using chemicals.

The modified carbon material according to the present invention is obtained by irradiating a carbon material with microwaves.
The carbon material is carbon fiber.
The carbon material is a carbon material obtained by firing a polymer material in which an atomic group containing a hetero atom such as nitrogen, oxygen, or sulfur is present in a main chain or a side chain.
Further, the polymer substance is a naturally derived material.
The natural material is a silk material.

In addition, the method for producing a modified carbon material according to the present invention includes a polymer material made of a naturally-derived material in which atomic groups containing heteroatoms such as nitrogen, oxygen, and sulfur are present in the main chain and side chains. And a process of forming a carbon material by firing at 500 ° C. to 1000 ° C. in an inert gas atmosphere, and a step of irradiating the carbon material with microwaves.
The natural material is a silk material.
The firing temperature is 600 to 800 ° C.
The temperature is raised to a firing temperature at a temperature elevation rate of 100 ° C. or less per hour, and the firing is performed at this firing temperature for several hours.

  According to the present invention, a modified carbon material having hydrophilicity and antibacterial properties can be provided. This modified carbon material is particularly suitable for use as a base material for medical gauze and bandage.

Carbon materials include high-molecular substances made of naturally-occurring materials such as silk, cotton, wool, etc., which contain atomic groups containing heteroatoms such as nitrogen, oxygen, and sulfur in the main chain and side chains. What was baked and carbonized is suitable. Particularly, carbonized silk material is suitable.
Hereinafter, a silk material will be described as an example.

    Here, the silk material is a general term for woven fabrics, knitted fabrics, powders, cotton, yarns, and the like made of rabbits or wild silk. These are fired alone or in combination.

  The firing temperature is preferably 1000 ° C. or lower. The firing atmosphere is performed in an inert gas atmosphere such as nitrogen gas or argon gas or in a vacuum to prevent the silk material from burning and ashing.

The firing conditions are such that rapid firing is avoided and the firing is performed in a plurality of stages.
For example, in an inert gas atmosphere, the temperature is raised at a moderate temperature increase rate of 100 ° C./hour, preferably 50 ° C./hour or less until the first firing temperature (for example, 500 ° C.). Hold for several hours and perform primary firing. Next, after cooling to room temperature, the temperature is gradually raised to a secondary firing temperature (for example, 700 ° C.) at a moderate temperature increase rate of 100 ° C. or less, preferably 50 ° C. or less per hour. The secondary firing is performed for several hours. Subsequently, it cools and the target silk sintered body is taken out from a baking furnace.
The firing conditions are not limited to the above, and can be appropriately changed depending on the type of silk material, the desired function of the fired body, and the like.

As described above, the baking is performed in a plurality of stages, the temperature is increased at a moderate temperature increase rate, and the baking is performed at a low temperature of 1000 ° C. or less. It has been found that rapid degradation of protein higher-order structures in which crystalline structures and crystalline structures are complicated is avoided, and various functions are produced particularly when a large amount of nitrogen components remain.
Moreover, by baking at a low temperature of 500 ° C. to 1000 ° C. or less, it is not graphitized, and a black glossy flexible (flexible) silk fired body is obtained.
From the viewpoint of water absorption (hydrophilicity) and antibacterial properties, which will be described later, it is preferable to fire at a low temperature of 600 ° C to 800 ° C.

FIG. 1 is a Raman spectrum diagram of a fired product when coarse-grained silk is fired at a high temperature of 2000 ° C. 2681cm ^-1, 1570cm ^-1, it is understood that graphitized since the peak at 1335cm ^-1 are observed.

  2, FIG. 3, and FIG. 4 are Raman spectrum diagrams of fired products when coarse-grained silk is fired at 700 ° C., 1000 ° C., and 1400 ° C., respectively. When the firing temperature is 1400 ° C., the peak value is low, but the peaks at the three locations are seen. In the case of a calcination temperature of 1000 ° C. or less, since the above-mentioned remarkable peak is not seen, it is considered that almost no graphitization has occurred.

Table 1 shows the result of elemental analysis (semi-quantitative analysis result) by electron beam microanalyzer of a fired product obtained by firing a silkworm silk knitted fabric at 700 ° C. in a nitrogen atmosphere.
The measurement conditions are acceleration voltage: 15 kV, irradiation current: 1 μA, probe diameter: 100 μm. In addition, the value in a table | surface shows the tendency of a detection element, and is not a guaranteed value.
As is clear from Table 1, it can be seen that a large amount of nitrogen element of 27.4 wt% remains. In addition, it can be seen that other elements derived from amino acids are multi-elements that remain.

Table 2 shows the elemental analysis results (semi-quantitative analysis results) of the fired product obtained by firing a silkworm silk spun knitted fabric at 1400 ° C. in a nitrogen atmosphere using an electron beam microanalyzer.
The measurement conditions are acceleration voltage: 15 kV, irradiation current: 1 μA, probe diameter: 100 μm. In addition, the value in a table | surface shows the tendency of a detection element, and is not a guaranteed value.
As is clear from Table 2, the residual amount of nitrogen element is reduced to 15.7 wt%.

Table 3 shows the elemental analysis results (semi-quantitative analysis results) of the fired product obtained by firing a rabbit non-woven fabric at 700 ° C. in a nitrogen atmosphere using an electron beam microanalyzer.
The measurement conditions are acceleration voltage: 15 kV, irradiation current: 1 μA, probe diameter: 100 μm. In addition, the value in a table | surface shows the tendency of a detection element, and is not a guaranteed value.
As is apparent from Table 3, a large amount of nitrogen element of 24.5 wt% remains.

FIG. 5 is an FE-SEM photograph when the silk material is fired at 700 ° C. On the surface, there is a thin film that appears to be due to baking residues derived from amino acids such as elemental nitrogen.
On the other hand, FIG. 6 is an FE-SEM photograph when the silk material is fired at a high temperature of 2000 ° C., but the surface is clean and the presence of the film as described above is not recognized.

Table 4 shows the antibacterial test results of the fired product obtained by firing the rabbit knitted fabric at 700 ° C. in a nitrogen atmosphere.
The test was conducted according to a JIS L 1902 quantitative test (unified test method).
Standard cotton cloth is used for unprocessed cloth. In the table, the number of unprocessed cloth bacteria indicates the number of bacteria grown by inoculating on unfired cloth.
In the table, for example, 1.9E + 04 is 1.9 × 10 ⁴ , and 4.3 is the logarithmic value thereof.

As is apparent from Table 4, in the case of the unprocessed cloth, the bacteria greatly proliferated, but in the case of the baked sample cloth, it can be seen that all the bacteria are greatly reduced and have an antibacterial action.
Thus, having an antibacterial action is due to the fact that a large amount of nitrogen derived from amino acids remains, particularly as described above, due to baking in multiple stages, a slow heating rate, and low temperature baking at 1000 ° C. or lower. I guess that.

  In the present invention, the fired product (carbon material) obtained by firing as described above is irradiated with microwaves (frequency: 2.45 GHz). When irradiating microwaves, it is advisable to sandwich the carbon material with an unglazed plate or the like in order to prevent the carbon material from burning and ashing.

  A 9 cm × 9 cm silk fabric was fired at 700 ° C. as described above, and the fired product was stored in a household microwave oven with an output of 500 W while being sandwiched between unglazed plates and irradiated with microwaves for 6 minutes.

  A 9 cm × 9 cm cotton fabric was fired at 700 ° C. as described above, and the fired product was stored in a household microwave oven with an output of 500 W while being sandwiched between unglazed plates and irradiated with microwaves for 6 minutes.

  A 9 cm × 9 cm wool fabric was baked at 700 ° C. as described above, and the baked product was stored in a household microwave oven with an output of 500 W while being sandwiched between unglazed plates and irradiated with microwaves for 6 minutes.

FIG. 7 is a 2000 times SEM photograph of the fired product (before microwave treatment) in Example 1,
FIG. 8 is a 5000 times SEM photograph of the fired product.
9 is a 2000 times SEM photograph of the fired product after the microwave treatment in Example 1, and FIG. 10 is a 5000 times SEM photograph thereof.

As shown in FIGS. 7 and 8, there is no unevenness on the surface of the fired product before the microwave treatment, but as shown in FIGS. 9 and 10, the surface of the fired product after the microwave treatment is Has fine irregularities.
When the water absorption rate was measured according to JIS L 1907, the water absorption rate of the fired product before the microwave treatment was 50%, but the water absorption rate of the fired product after the microwave treatment was greatly increased to 87%. .
This is thought to be because, since the irregularities are formed on the surface of the fired product after the microwave treatment as described above, the contact angle of water with respect to the surface of the fired product is reduced and wettability is improved.

As described above, unevenness occurs on the surface of the fired product by performing microwave treatment. By firing a polymer material made of a naturally-derived material at a low temperature of 1000 ° C. or less, nitrogen element or the like remains, It is considered that these nitrogen elements are affected by the microwave treatment.
Incidentally, in the case of a carbon material obtained by microwave processing of a fired product obtained by firing a silk material at 1400 ° C. and 2000 ° C., the water absorption was not improved.

In addition, as described above, the fired product fired at a low temperature of 1000 ° C. or less has antibacterial properties, but even when the fired product (carbon material) fired at this low temperature is subjected to microwave treatment, it is antibacterial. It was confirmed that
As described above, since the water absorption is improved (that is, the hydrophilicity is improved) and the antibacterial property is maintained by the microwave treatment, these modified carbon materials are based on medical gauze and adhesive bandages. It can be suitably used as a material. In particular, when used as a gauze, it is suitable because it is a carbon material and does not adhere to the wound.

  In addition, it can be effectively used as a material mixed in ink, paste, etc., an electrode material for a fuel cell, a reinforcing material for various composite materials, and the like.

It is a Raman spectrum figure of a baked product at the time of baking coarse grain silk at the high temperature of 2000 degreeC. It is a Raman spectrum figure of a baked material at the time of baking coarse grain silk at the high temperature of 700 degreeC. It is a Raman spectrum figure of a baked product at the time of baking coarse grain silk at the high temperature of 1000 degreeC. It is a Raman spectrum figure of a baked product at the time of baking coarse grain silk at the high temperature of 1400 degreeC. It is a FE-SEM photograph figure at the time of baking a silk raw material at 700 degreeC. It is a FE-SEM photograph figure at the time of baking a silk raw material at 2000 degreeC. 2 is a 2000 times SEM photograph of a fired product (before microwave treatment) in Example 1; It is a 5000 times SEM photograph of the baked product in FIG. 2 is a 2000 times SEM photograph of a fired product after microwave treatment in Example 1; 10 is a 5000 times SEM photograph of the fired product in FIG. 9.

Claims (9)

  A modified carbon material obtained by irradiating a carbon material with microwaves.   The modified carbon material according to claim 1, wherein the carbon material is carbon fiber.   The modified carbon material according to claim 1, wherein the carbon material is a carbon material obtained by firing a polymer material in which an atomic group containing a hetero atom such as nitrogen, oxygen, or sulfur is present in a main chain or a side chain. Quality carbon material.   4. The modified carbon material according to claim 3, wherein the polymer material is a naturally derived material.   5. The modified carbon material according to claim 4, wherein the naturally derived material is a silk material. A polymer substance made of a naturally-derived material in which an atomic group containing a heteroatom such as nitrogen, oxygen or sulfur is present in the main chain or side chain is heated to 500 ° C. to 1000 ° C. in an inert gas atmosphere. Forming a carbon material by firing at a temperature;
And a step of irradiating the carbon material with microwaves.   The method for producing a modified carbon material according to claim 6, wherein the naturally derived material is a silk material.   The method for producing a modified carbon material according to claim 6 or 7, wherein the firing temperature is 600 to 800 ° C.   The method for producing a modified carbon material according to any one of claims 6 to 8, wherein the temperature is raised to a firing temperature at a heating rate of 100 ° C or less per hour and kept at the firing temperature for several hours for firing. .