JP2003306389A - Glassy carbon felt and water-repellent oil absorbent material and oil separation process using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material which can be used as an oil absorbent material which exerts excellent resistances to water, detergents, chemicals and heat and an excellent recyclability and handleability after absorbing oil, shows an excellent oil absorption and water repellency capable of selectively absorbing oil in a mixed system of water and oil and does not release the absorbed oil into water upon being thrown into water, a water-repellent oil absorbent material and an oil separation process for an oil-water mixture using the same. <P>SOLUTION: The glassy carbon felt exerting an excellent oil absorption while retaining a water repellency, a chemical resistance and a heat resistance is manufactured by baking a felt essentially comprising a phenol resin fiber, especially a novolac phenol resin fiber which has been cured with formalin after melt spinning, in an inert gas atmosphere at 800-2,000°C. The water- repellent oil absorbent material is manufactured using this. The oil separation process uses this. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glassy carbon felt, a water-repellent oil-absorbent material, and an oil-water separation method, and more specifically, it is made by fibrating a phenolic resin into a felt and then baking it to obtain water-repellent and oil-absorbing properties. And a water-repellent oil-absorbing material using the glassy carbon felt and a method for separating oil-water from an oil-water mixture using the same.

[0002]

2. Description of the Related Art Conventionally, household wastewater and industrial wastewater often contain oil, which is one of the causes of environmental pollution. In addition, oil and petroleum products have been spilled into rivers and the sea due to grounding of tankers. In addition, there are unlawful dumping of oil into rivers and the sea, and there are accidents of spillage of crude oil and the like due to damage to offshore oil mining bases and stockpiling bases. Therefore, the collection and separation and collection of oil from the wastewater of factories and households, and from the water in rivers, lakes and seas has become an urgent issue.

Various kinds of adsorbents and absorbents have been conventionally used for collecting and separating and collecting oil from water. For example, a cloth or woven cloth made of natural fibers or synthetic fibers is suitable for wiping off oils attached to the floor surface, wall surface, etc. of a road or equipment. Further, it is also possible to lay it on the water surface of the oil-water mixture to adsorb oils. Furthermore, for the treatment of oil-containing wastewater and spilled crude oil, inorganic oil absorbing materials such as silica, clay and perlite, polyolefin fibers, crosslinked polymers of alkyl acrylate, and organic oil absorbing materials such as polynorbornene rubber are used. ing. However,
The inorganic oil-absorbing material is originally a hydrophilic oil-absorbing material, and a mixed system of water and oil preferentially absorbs water, so that the oil-absorbing ability is not always sufficient. Moreover, once the oil is absorbed, it is absorbed into the water. In addition, the absorbability of oil emulsified with detergent or the like is low, and when the oil is adsorbed and then treated with the detergent, the adsorbed oil is released. As described above, the inorganic oil absorbing material merely adsorbs oil and is inferior in selective oil absorption, water resistance, detergent resistance, and emulsion oil adsorption. On the other hand, an organic oil absorbing material can selectively adsorb oil in a mixed system of water and oil, and does not release oil into water even if the oil absorbing material that has once absorbed oil is thrown into water. Therefore, the organic oil absorbent is superior to the inorganic oil absorbent in terms of selective oil absorption and water resistance, but on the other hand, it lacks emulsified oil adsorption and detergent resistance. Further, it is also inferior in the controlled release control after adsorption of the volatile oily substance, handleability after oil absorption and heat resistance.

As described above, since the conventional oil absorbing material has various problems, for example, in JP-A-10-43585, thermal expansion is performed as an oil absorbing material that does not absorb water, that is, has water repellency. In a bag-shaped container made of a non-woven fabric of organic synthetic fiber, graphite is also disclosed in JP-A-11-4773.
In JP-A No. 2000-17014, there is disclosed in JP-A-2000-17014 an oil absorbing material in which plastic powder is fused to the surface of a carbon porous body.
Various publications have been proposed in Japanese Patent No. 5 such as an oil adsorbent made of obsidian perlite coated with hydrophobic silica that does not absorb water. In addition, there are some felt-shaped ones such as polypropylene and polyethylene mixed or coated with additives, and further, “Sorption, recovery and recycling of leaked heavy oil by carbon material” by Inagaki et al.
02 [No. 201] pp. 16-25), expanded graphite,
A woven fabric of activated carbon and carbon fiber, an oil absorbing material using felt, and the like, which are evaluated for sorption capacity (adsorption capacity, absorption capacity) of heavy oil, are disclosed.

However, most of the conventional oil-absorbing materials and the proposed / disclosed materials have oil-absorbing properties and water-repellent properties by using additives and coating materials, but the binding properties and temperature Due to the variation caused by the characteristics, the conditions of use (temperature range limitation, use of chemicals or solvent mixture is prohibited, attention of fire or static electricity, non-formability, etc.) for exerting their performance are limited. Further, some oil absorbing materials using only carbon materials have suppressed water adsorption in the atmosphere, but have no water repellency. Furthermore, it is difficult to reuse the absorbed oil or oil-absorbent material, and when burning after oil absorption,
There are also problems that the oil absorbing material generates toxic gas and that the oil absorbing material itself becomes high temperature and damages the incinerator.

On the other hand, carbon fibers and activated carbon fibers which use heat-infusible fibers such as novoloid fibers have been conventionally known.
For example, “Kynol” (R), “Kynol (R) carbon fiber”, “Kynol (R) activated carbon fiber” and the like. However, these are heat resistant and highly flameproof,
It has good affinity with resins and rubbers and excellent chemical resistance, but it has the feature (defect) that it is not water repellent.
In addition, glassy carbon (carbon), water repellency, heat resistance,
Although it is known as having excellent chemical resistance and conductivity, it has a feature (defect) that it is not oil-absorbing.

[0007]

Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to absorb oil selectively in a mixed system of water and oil, and is excellent in oil absorption and water repellency. , Once used as an oil absorbent, it does not release oil into the water even if it is thrown into water, and it is also excellent in water resistance, detergent resistance, chemical resistance, handleability after oil absorption, reusability, and heat resistance. (EN) Provided are a raw material, a water-repellent oil-absorbing material, and an oil-water separation method of an oil-water mixed liquid using the same.

[0008]

In view of the above problems, the present inventor has made earnest studies on materials and the like that can be used as water-repellent oil-absorbing materials, and as a result, found that glassy carbon of a specific material is water-repellent. It has been found that it has excellent heat resistance, chemical resistance, and electrical conductivity, but by further forming a felt shape, it has excellent oil absorption. The present invention has been completed based on these findings and further investigations.

That is, according to the first aspect of the present invention,
A glassy carbon felt excellent in oil absorption while maintaining water repellency, chemical resistance, and heat resistance, which is made of a phenol resin fiber-based felt under an inert gas atmosphere at 800 to
A glassy carbon felt obtained by firing at a temperature of 2000 ° C is provided. Further, according to the second invention of the present invention, there is provided a glassy carbon felt according to the first invention, wherein the phenol resin fiber is a novolac type phenol resin fiber cured with formalin after melt spinning. To be done. Further, according to a third invention of the present invention, there is provided the glassy carbon felt according to the first invention, characterized in that the basis weight of the fiber felt before firing is 100 to 350 g / m ² .

According to a fourth aspect of the present invention, there is provided a glassy carbon felt according to any one of the first to third aspects, wherein the firing temperature is 1000 to 1200 ° C. Further, according to a fifth aspect of the present invention, there is provided a water-repellent oil-absorbing material comprising the glassy carbon felt according to any one of the first to fourth aspects. Further, according to the sixth invention of the present invention, the glassy carbon felt of any one of the first to fourth inventions is applied to the oil-water mixture, and the oil is adsorbed or absorbed in the felt. An oil-water separation method is provided, which comprises removing and collecting an oil component in an oil-water mixture.

As described above, the present invention is a glassy carbon felt excellent in oil absorption while maintaining water repellency, chemical resistance and heat resistance, which is mainly composed of phenol resin fiber and is made of an inert gas atmosphere. The present invention relates to a glassy carbon felt formed by firing at a temperature of 800 to 2000 ° C., a water-repellent oil-absorbent material using the glassy carbon felt, and the like. Included. (1) The glassy carbon felt according to the first or second invention, wherein the fiber is a novoloid fiber. (2) In the first or second invention, the glassy carbon felt has a fiber diameter of 5 to 30 μm and a carbon content of 90 to.
Glassy carbon felt, characterized in that it is 99.9% by weight. (3) The glassy carbon felt according to the third invention, wherein the weight of the fiber felt before firing is 200 to 300 g / m ² .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. 1. Glassy carbon felt The glassy carbon felt of the present invention has water repellency, chemical resistance,
A glassy carbon felt excellent in oil absorption while maintaining heat resistance, which is obtained by firing a felt mainly composed of a phenol resin fiber at a temperature of 800 to 2000 ° C. in an inert gas atmosphere.

The phenolic resin used as a raw material is
It may be a resol type, a novolak type, or a combination of these. In particular, a novolak type having a linear structure represented by the following chemical structural formula is preferable. The novolac type phenol resin can be obtained as a product having a linear structure by reaction of phenol and formalin with an acidic catalyst.The fiber is melt-spun and then cured with formalin. It is manufactured by, for example, known as novoloid fiber.

[0014]

[Chemical 1] (In the formula, m is an integer of 1 or more, and n is 1 or 2.)

Further, as the phenol resin fiber in which the resol type and the novolac type are combined, for example, there is a fiber obtained by coating a novoloid fiber with a resol type phenol resin, which is commercially available as "Kynol" (registered trademark) from Nippon Kynol Co., Ltd. Available and available.

As a method for producing a glassy carbon felt, fibers are made into a felt shape and then fired at a temperature of 800 to 2000 ° C. in an inert gas atmosphere, for example, a nitrogen atmosphere to form glassy carbon. Is. The firing temperature is preferably 1000 to 1200 ° C. The carbonizing atmosphere may be in vacuum instead of the inert gas atmosphere. If the firing temperature is lower than 800 ° C. or firing in an oxygen atmosphere, the water repellency effect cannot be obtained, while
Even if the temperature exceeds 2000 ° C, the effect of increasing the temperature cannot be obtained. Before glassy carbon reduction, for example, novoloid fibers of the felt basis weight is 150 to 300 g / ^{m 2,} preferably 200-30Og / ^{m 2.}

The obtained glassy carbon felt is one of the carbon fiber felts in a broad sense. However, the applications of general carbon fiber felts are usually separators for sodium-sulfur batteries and alkaline batteries, reinforcing materials, filters for fine powders, etc. In many cases, polyacrylonitrile (PAN) and pitch are the mainstream as starting materials for carbon fibers. However, the glassy carbon felt starting from the phenolic resin of the present invention has water repellency that is not found in carbon fibers using PAN or pitch as a raw material or those obtained by graphitizing or activated carbonizing them. Moreover, it also has excellent oil absorption. The oil absorbency is about 10 to 30 times its own weight.

Further, regarding the basic properties and structure of the glassy carbon felt, the fiber diameter is 5 to 30 μm, the carbon content is 90 to 99.9% by weight, and the electrical specific resistance is 0.005 to 5.
0.3 ~ woven with 0.05Ωcm glassy carbon
It is a non-woven fabric having an arbitrary thickness of 3.0 mm, and has chemical resistance, heat resistance, and static electricity suppressing property as performances other than the above-mentioned water repellency and oil absorption.

2. Water-repellent oil-absorbent material The water-repellent oil-absorbent material of the present invention is characterized by using the above-mentioned glassy carbon felt. As described above, the novoloid fiber has the property of not being water repellent, and the glassy carbon made of a thermosetting resin such as a phenolic resin has water repellency, heat resistance, chemical resistance, and conductivity. Although excellent, it has the property of not being oil-absorbing. The glassy carbon felt according to the present invention has excellent heat resistance, chemical resistance, conductivity, etc., and has both water repellency and oil absorption properties by forming the glassy carbon of a specific material into a felt shape. It is possible. Since the glassy carbon felt of this specific material has both water repellency and oil absorption properties, it can be used as a water repellent oil absorption material.

Although the detailed mechanism by which the glassy carbon felt of this specific material has both water repellency and oil absorbency is not clear, the present inventors consider as follows. That is, the glassy carbon felt of the present invention (product of the present invention)
Then, a small amount of water drops will make it spherical. This is not affected by the surface tension of the product of the present invention, and by the surface tension of water,
It has a spherical shape so that the free energy has a minimum shape. Next, when a small amount of oil is poured, it becomes a thin disk shape instead of a spherical shape, and then is absorbed inside the product of the present invention. The "disc shape" is a state in which the surface tension of the product of the present invention spreads the liquid against the surface tension of the oil and can be said to have affinity. It is presumed that "being absorbed into the interior" is caused by the affinity between the product of the present invention and oil, and the permeability because the product of the present invention is a nonwoven fabric. In addition, when a general carbon fiber felt made of PAN or pitch as a raw material and a raw material (phenol resin fiber before carbonization) of the product of the present invention, both oil and water show a similar disk-like absorption behavior. . Considering the case of water in this case, since the surface tension of the material other than the product of the present invention acts on the surface tension of water, it is presumed that a capillary phenomenon accompanying it is occurring, and the cause of the action of this surface tension. Is presumed to be different in the intermolecular force with respect to water molecules, structure, and functional group depending on the raw material, production method, and oxidation state different from those of the present invention. In particular, carbon fibers having a large specific surface area such as a PAN-based or pitch-based fiber structure having a layered structure or a graphite structure are less likely to be water repellent. Since the product of the present invention is carbonized under the conditions for vitrifying a specific phenolic resin-based felt, it is closer to the structure of complete glassy carbon than other materials, and it is presumed that the above difference occurred. It

As a method of using the water-repellent oil-absorbing material of the present invention, for example, a product of the present invention processed into a size capable of absorbing only the weight of the oil to be absorbed may be applied to the oil, the solution-absorbed portion, etc.
Examples include installation, oil immersion, and contacting. Also,
The water-repellent oil-absorbing material of the present invention has good oil-absorbing property (10 to 10 of its own weight).
30 times) and water repellency, water to be treated containing a small amount of oil, or an oil-water mixture, using this water-repellent oil-absorbent material, that is, by applying the above-mentioned glassy carbon felt,
By absorbing or absorbing oil in the felt,
The oil in the water to be treated or the oil-water mixture can be removed and recovered, and as a result, the oil-water mixture can be separated well. Furthermore, if you want to absorb unspecified oil, or if you want to leave it for a long time, any thick product of the present invention, or
A product obtained by laminating and adhering some of the products of the present invention, a product processed into a bag shape, a powder form, or the like can be appropriately used.

Since the water-repellent oil-absorbent material of the present invention has oil-absorbing property and water-repellent property, it can adsorb oil components from not only the oil liquid but also the oil-water mixed liquid, so that it has chemical resistance, heat resistance and static electricity suppression. Oil absorbing material or fire type, reducing material, electrode material, oil filter, sanitary material (oil removal, leak prevention material,
It can be used as a patch.

[0023]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The performance evaluation in Examples and Comparative Examples was carried out according to the following evaluation methods and criteria. (1) Oil absorption evaluation A 30 mm × 30 mm felt oil absorbing material (Example 1, Comparative Examples 1 and 2) or 2 g of oil absorbing material (Comparative Examples 3 to 5) was immersed in edible oil and left in that state for 1 hour. Then, the increase in weight of the oil absorbing material was measured and evaluated as the oil absorbing property. In addition, the powdery one is
It was dipped in a state of being wrapped in gauze. The evaluation standard is a four-level evaluation, and the weight increase rate of 500% by weight or more is ◎, 100 to
500% by weight was ◯, 10 to 100% by weight was Δ, and 10% by weight or less was X.

(2) Evaluation of water repellency (water absorption) A 30 mm × 30 mm felt oil absorbing material (Example 1, Comparative Examples 1 and 2) or 2 g of oil absorbing material (Comparative Examples 3 to 5) was immersed in tap water, After standing for 1 hour in that state, the weight increase of the oil-absorbent material was measured and evaluated as water repellency (water absorption). The powdery material was immersed in gauze. The evaluation criteria were four-level evaluation, and the weight increase rate was 500% by weight or more, x was 100 to 500% by weight, Δ was 10 to 100% by weight, and 10% by weight or less was ⊚.

(3) Evaluation of heat resistance 40 mm of 30 mm × 30 mm felt oil absorbing material (Example 1, Comparative Examples 1 and 2) or 2 g of oil absorbing material (Comparative Examples 3 to 5) was used.
After heating at 0 ° C. in an air atmosphere for 1 hour, the above (1) oil absorption evaluation and (2) water repellency evaluation were carried out.

(4) Reusability evaluation After dipping a 30 mm × 30 mm felt oil absorbing material (Example 1, Comparative Examples 1 and 2) or 2 g of oil absorbing material (Comparative Examples 3 to 5) in edible oil for 1 hour, 500 N After releasing the edible oil from the oil absorbing material by applying a load for 10 minutes, the above (1) oil absorption evaluation and (2) water repellency evaluation were carried out.

(5) Acid resistance (chemical resistance) evaluation 30 mm × 30 mm felt oil absorbing material (Example 1, Comparative Examples 1 and 2) or 2 g oil absorbing material (Comparative Examples 3 to 5) was used with hydrofluoric acid and nitric acid. After being immersed in the mixed liquid (1: 1) for 1 hour, the above (1) oil absorption evaluation and (2) water repellency evaluation were carried out.

[Example 1] As a raw material fiber, a felt of novoloid fiber ("Kynol S210" (R) sold by Nippon Kynol Co., Ltd.) was used, and in a nitrogen atmosphere, a temperature rising rate of 0.7 ° C / minute and an ultimate temperature of 1000. A glassy carbon felt was obtained when carbonized at ℃. The oil absorption and water repellency of the obtained glassy carbon felt were measured and evaluated. The results are shown in Table 1.

[Comparative Example 1] As an oil absorbing material, activated carbonized felt (“Kynol S21” sold by Nippon Kynol Co., Ltd.) was used.
0 "(R) activated carbon felt),
The oil absorbency and water repellency were measured and evaluated. The results are shown in Table 1.

[Comparative Example 2] As a commercially available water-repellent oil-absorbent material, polyethylene felt ("HP-556" manufactured by As One Co., Ltd.) was used to measure oil-absorption property and water repellency.
evaluated. The results are shown in Table 1.

[Comparative Example 3] As an oil absorbing material, the diameter was 50 to 6
Using a molded glassy carbon porous body (thickness 10 mm) produced by sintering 0 μm glassy carbon fine particles, oil absorption and water repellency were measured and evaluated. The results are shown in Table 1.

[Comparative Example 4] As an oil absorbing material, a glassy carbon powder (true spherical carbon fine particles, particle size 5) prepared by vitrifying phenolic resin fine particles manufactured by Gunei Chemical Industry Co., Ltd. into glassy carbon.
0 μm) was used to measure and evaluate oil absorbency, water repellency and the like.
The results are shown in Table 1.

[Comparative Example 5] As an oil absorbing material, graphite powder (crushed carbon fine particles) (average particle diameter of about 100 μm)
(SGP-100, manufactured by SCC Co., Ltd.) was used to measure and evaluate oil absorbency, water repellency and the like. The results are shown in Table 1.

[0034]

[Table 1]

As is clear from Table 1, the glassy carbon felt (oil absorbing material) obtained in Example 1 was found to be excellent in oil absorbency and water repellency under the conditions evaluated. On the other hand, in Comparative Example 1 using the activated carbon felt, the oil absorbency is good but the water repellency is not so good under the evaluated conditions. In Comparative Example 2 using a commercially available polyethylene-based felt, the oil absorption after reuse and the water repellency after the acid resistance evaluation are poor. In Comparative Examples 3 and 4 using the glassy carbon porous material or powder, the oil absorbency and water repellency are not so good. Further, in Comparative Example 5 using the graphite powder, the oil repellency is good but the water repellency is poor under the evaluated conditions.

[0036]

EFFECT OF THE INVENTION The glassy carbon felt of the present invention is obtained by firing a fiber obtained from a specific resin into a felt and then firing it at a temperature of 800 to 2000 ° C. in an inert gas atmosphere. It is characterized by having an aqueous property and an oil absorption property.
Therefore, the glassy carbon felt can be suitably used as a water-repellent oil-absorbing material and has 10 to 30 times its own weight of oil-absorbing property and water-repellent property, so that an oil-water mixed liquid can be effectively separated. In addition, the water-repellent oil-absorbing material of glassy carbon felt has the characteristics (chemical resistance, heat resistance, and conductivity) peculiar to glassy carbon, so it can be used in fire, mixed oil, and high temperature. It has the characteristic that there is no fear of ignition due to static electricity because it has no electrostatic properties. Further, since it is a single element oil-absorbing material, there is no concern that another component derived from the oil-absorbing material will dissolve into the absorbed oil or the separated solution under any conditions. Also,
The oil absorbing material itself can be reused by combustion treatment, squeezing, or centrifugation. The glassy carbon felt of the present invention is used as a base material for sanitary materials (oil remover, leakage preventive material, adhesive material), a base material for textile products, a filter for qualitative analysis, etc., in addition to the use of oil absorbent materials and general carbon fiber felts. it can.

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Claims (6)

[Claims] 1. A glassy carbon felt excellent in oil absorption while maintaining water repellency, chemical resistance, and heat resistance, wherein a felt mainly composed of phenol resin fibers is used in an inert gas atmosphere at 800 to 2000 ° C. Glassy carbon felt that is fired at the temperature of. 2. The glassy carbon felt according to claim 1, wherein the phenol resin fiber is a novolac type phenol resin fiber which is cured by formalin after melt spinning. 3. The unit weight of felt before firing is 100 to 3
The glassy carbon felt according to claim 1, wherein the glassy carbon felt has a weight of 50 g / m ² . 4. The glassy carbon felt according to claim 1, wherein the firing temperature is 1000 to 1200 ° C. 5. A water-repellent oil-absorbing material comprising the glassy carbon felt according to claim 1. 6. An oil component in an oil / water mixture by applying the glassy carbon felt according to claim 1 to the oil / water mixture, and adsorbing or absorbing the oil component in the felt. A method for separating oil and water, which comprises removing and recovering.