JP2000202235A - Sheet-shaped material for removing malodorous gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet-shaped material for removing malodorous gas capable of easily obtaining the filter having high removing capacity to the malodorous gas and also low in pressure loss when the matter is subjected to fabrication. SOLUTION: This sheet-shaped material is composed of the activated carbon fiber having >=0.7 ml/g fine pore volume and >=2.0 nm average fine pore diameter and a heat fusible fiber, and the constitution ratio is (50:50) to (90:10) by weight. The sheet-shaped matter has <=0.5 mm thickness and keeps >=25 g/m2 phosphoric acid in the sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a filter application,
In particular, the present invention relates to a sheet-like material for removing odorous gas which is suitable for use as a filter for a clean room.

[0002]

2. Description of the Related Art Sheets using activated carbon fibers are well known and have been used for filters for removing various organic gases. Further, in order to remove a gas that cannot be physically adsorbed by activated carbon fiber, a chemical is attached to the activated carbon fiber, and it is also used for a chemical filter. As the shape of these filters, a flat corrugated sheet and a corrugated sheet are alternately stacked, and a honeycomb-shaped corrugated filter is often used because of its low pressure loss, and a sheet made of activated carbon fiber is processed into these shapes. At present, it is being used as a filter for clean rooms of semiconductor factories and the like, and is becoming indispensable.

[0003] Since the performance and life as a chemical filter depend on the amount of the adhering chemical, a sheet holding a larger amount of the adhering agent is required to produce a high-performance filter. An activated carbon fiber sheet having more activated carbon fibers holding the carbon fibers is required.
However, when the amount of the activated carbon fiber holding the adsorbent is increased, the amount of the adsorbent held as the activated carbon fiber sheet is increased, but the thickness of the sheet is increased and the pressure loss of the corrugated filter is increased, and the use as a filter is increased. Cause trouble. In particular, the activated carbon fiber sheet has a higher bulk density and a higher flexural rigidity as compared with a fiber sheet made of a general thermoplastic resin, so that the fibers in the sheet easily swell, and it is difficult to reduce the thickness of the sheet. Therefore, the only way to reduce the thickness is to reduce the amount of activated carbon fibers. As a result, only a sheet having a small amount of the adhering agent could be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and to provide a sheet-like material for removing malodorous gas, which is capable of producing a filter having a high chemical adsorption capacity and a low pressure loss. Is what you do.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention comprises activated carbon fibers having a pore volume of 0.7 ml / g or more and an average pore diameter of 2.0 nm or more and heat-fusible fibers, and the composition ratio is 50:
It is a sheet-like material having a thickness of 50 to 90:10, and the thickness of the sheet is 0.5 mm or less.
The object of the present invention is to provide a sheet-like material for removing odorous gas, characterized in that it has a g / m ² or more.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, the activated carbon fiber constituting the sheet-like material for removing offensive odor gas of the present invention together with the heat-fusible fiber will be described.
Activated carbon fiber in the present invention, pitch-based, phenol-based, cellulose-based, etc. can be used,
The pore volume is 0.7 ml / g or more and the average pore diameter is 2.0
nm or more. The sheet-like material of the present invention holds phosphoric acid at 25 g / m ² or more as described later, but has a pore volume of less than 0.7 ml / g or an average pore diameter of 2. When the thickness is less than 0 nm, the amount of phosphoric acid present in the sheet is small when a sheet having a thickness within a range in which pressure loss can be tolerated is small even when phosphoric acid is impregnated into the activated carbon fiber. Since it is too high, the performance and life as a chemical filter cannot be sufficiently satisfied, and the object of the present invention cannot be obtained as a sheet for removing a bad odor gas for a filter.

[0007] Next, the heat-fusible fibers constituting the sheet-like material of the present invention together with the activated carbon fibers are used to fix the fibers between the activated carbon fibers in order to maintain the shape of the activated carbon fibers in a low thickness state. The activated carbon fiber sheet has a higher bulk density and a higher bending rigidity than a fiber sheet made of a general thermoplastic resin, so that the fibers in the sheet easily swell and it is difficult to reduce the thickness of the sheet. In the present invention, in order to suppress the thickness of the sheet-like material, it is necessary to use the activated carbon fiber and the heat-fusible fiber in a weight ratio of 50:50 to 90:10. If the weight ratio of the heat-fusible fibers in the sheet material exceeds 50%, the thickness of the sheet material can be reduced, but the ratio of the activated carbon fibers becomes too small, and the adsorption capacity of the activated carbon fibers and the activated carbon The amount of phosphoric acid retained in the fiber is reduced, and only a sheet-like material whose performance and life cannot be sufficiently satisfied when a chemical filter is formed can be obtained. Further, the weight ratio of the heat-fusible fibers in the sheet material is 1%.
If it is less than 0%, the ratio of the activated carbon fiber becomes too high, the thickness of the sheet increases, and the pressure loss when a chemical filter is formed increases. Therefore, the weight ratio between the activated carbon fiber and the heat-fusible fiber is 50:50 to 90:10, particularly 6
5:35 to 85:15 is preferred.

It is not preferable to use a solution-type binder resin such as an emulsion binder in order to maintain the form of the sheet-like material, since the binder blocks pores existing in the activated carbon fiber. In such a case, phosphoric acid and the binder may react, which is not preferable. Activated carbon fibers also have low mechanical strength and the like as compared with general synthetic fibers and the like due to their properties, so that sheet-like materials having activated carbon fibers as constituent fibers tend to be similarly weak in strength. In terms of compensating for the drawbacks, the heat-fusible fiber which functions as a reinforcing fiber at the same time as retaining the shape is optimal.

In the present invention, it is preferable that the activated carbon fibers which are in contact with the heat fusible fibers are fused and adhered only at the contact points by melting the polymer. Furthermore, in the case of a core-sheath conjugate fiber in which a low-melting-point polymer is disposed in the sheath component and a high-melting-point polymer is disposed in the core component, the sheath component adheres to each other by heat fusion. Since it does not deteriorate or become irregular, it becomes one of the fibers constituting the sheet-like material, and is particularly preferable because the mechanical performance of the sheet-like material is improved. It is suitable for various reasons.

The polymer used for the heat-fusible fiber is preferably a polyamide-based, polyester-based, or polyolefin-based polymer from the viewpoints of fiber forming properties, heat-fusing properties, and chemical resistance. Polyamide polymers such as nylon 6, nylon 46, nylon 66, etc .; polyester polymers such as polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate copolymerized with isophthalic acid; polyethylene, polypropylene, etc. Polyolefin-based polymers, and blends of these polymers, and those composed of these copolymers are also included, as long as the effects of the present invention are not impaired, matting agents, pigments, flame retardants, defoamers Any additive such as an agent, an antistatic agent, an antioxidant, and an ultraviolet absorber may be added.

In the sheet of the present invention, a single or composite heat-fusible fiber formed of one or two of these polymers is used. The fineness of the fusible fiber is preferably from 0.5 d to 5 d, particularly preferably from 1 d to 3 d, from the viewpoint of fiber strength and adhesive strength.

[0012] The agent held by the sheet of the present invention is
Phosphoric acid must be used because it is intended to remove malodorous gas such as ammonia gas. It is important to keep phosphoric acid in the sheet-like material at 25 g / m ² or more from the viewpoint of performance when a chemical filter is used, and in order to realize this, in the present invention, as described above, pores are used. Activated carbon fibers having a volume of 0.7 ml / g or more and an average pore diameter of 2.0 nm or more are used. To simply increase the amount of phosphoric acid in the sheet-like material, the weight of the activated carbon fiber impregnated with phosphoric acid may be increased. However, the thickness of the sheet increases, and a corrugated filter with low pressure loss cannot be manufactured. Therefore, in the present invention, since the amount of phosphoric acid to be impregnated is increased without increasing the weight of activated carbon fibers in the sheet-like material, the optimum pore volume for phosphoric acid impregnation is 0.7 ml / g or more, and the average pore diameter is By using activated carbon fibers having a thickness of 2.0 nm or more, it is possible to obtain a sheet having a low thickness and a high retention amount for removing odorous gas, which has been conventionally contradictory.

FIG. 1 is a sectional view showing an embodiment of a filter obtained by corrugating a sheet-like material of the present invention. As is clear from FIG. 1, in the corrugated filter using the sheet-like material of the present invention, when the outer shape is constant, the cell size of the corrugate filter that is the air flow path decreases as the thickness of the sheet-like material increases, It can be seen that the pressure loss increases. However, in the present invention, it is possible to provide a low pressure loss corrugated filter having a large air flow path by reducing the thickness of the sheet.

Next, a method for producing the sheet material for removing odorous gas of the present invention will be described. Note that the method described here is merely an embodiment of the method for producing a sheet-like material of the present invention, and the present invention is not limited thereto. In order to manufacture the sheet-like material of the present invention, first, activated carbon fibers and heat-fusible fibers are mixed at a predetermined weight ratio, and then, using a card machine such as a random card or a parallel card, the activated carbon fibers and heat-fusible fibers are mixed. Form a nonwoven web of fibers. At this time, the method of cross-lapping the non-woven web with a cross wrapper or the like according to the basis weight and mechanically generating three-dimensional entanglement of the fibers with a needle punch device to form an integrated non-woven web is also appropriate. Can be adopted. A nonwoven web composed of the activated carbon fibers and the heat-fusible fibers thus obtained,
The fiber is passed through a dryer set at a temperature equal to or higher than the melting point of the heat-fusible fiber and lower than (melting point + 40) ° C., and the fibers of the nonwoven web-like activated carbon fiber are fixed by heat-sealing the heat-fusible fiber. The sheet is formed into a sheet, and a sheet-like material having a reduced thickness is obtained by using a thermocompression welding device having a pair of two flat rolls.

In order to retain phosphoric acid on the sheet-like material of the present invention, a method of obtaining a sheet-like material by the above-mentioned method using activated carbon fiber impregnated with phosphoric acid, and a method of producing a sheet-like material produced by the above-mentioned method. There are two types of manufacturing methods in which phosphoric acid is later impregnated into the product. Examples of the method of impregnating the sheet material with phosphoric acid later include: an impregnation method in which the sheet material is immersed in a phosphoric acid solution using a mangle impregnating machine or the like; The phosphoric acid solution is applied to the sheet using a roll coating method, a doctor knife or the like, a knife coating method for uniformly coating the phosphoric acid applied on the sheet using a doctor knife, or a spray gun. The most suitable method is selected depending on the concentration of the phosphoric acid solution and the viscosity, etc., and the phosphoric acid is held at 25 g / m ² or more in the sheet to obtain the desired sheet. it can.

[0016]

Next, the present invention will be described in detail with reference to examples. In the examples, the measurement of each characteristic value was performed as follows. (1) Melting point of polymer Melt endothermic peak measured at a heating rate of 20 ° C./min using a DSC-7 type differential scanning calorimeter manufactured by PerkinElmer.
The temperature giving the maximum value of the peak was defined as the melting point. (2) Pore volume and average pore diameter of activated carbon fiber Using a bell soap automatic gas adsorption device manufactured by Japan Bell Co., Ltd., the low pressure nitrogen adsorption method by BET multipoint method, the pore volume is a relative pressure of 1.0, The specific surface area (m ² / g) was measured at a relative pressure of 0.1, and the average pore diameter was calculated by the following equation. Average pore diameter = pore volume × 4 / specific surface area (3) Concentration of ammonia gas It is a value measured by using a Kitagawa gas detector tube manufactured by Komei Rikagaku Kogyo Co., Ltd. for ammonia gas. (4) 1 point per 1 m ² of phosphate amount sheet of the sheet-like material is cut out three as 10 cm × 10 cm, 400 meters of phosphoric acid during its seat
1N of NaO in the phosphoric acid washing solution.
After adding H to adjust the pH of the solution to 9 or more, a back titration was performed using 1N-HCl, and the obtained values were averaged and converted per 1 m ² . (5) Thickness of sheet-like material It is a value measured according to JIS-L1096.

Example 1 The pore volume is 0.8 ml / g and the average pore diameter is 2.1 nm.
Of pitch-based activated carbon fiber and isophthalic acid as a sheath component
Activated carbon fiber 80 was prepared by combining a copolymerized polyethylene terephthalate polymer having a melting point of 110 ° C. obtained by copolymerization with mol% and a heat-fusible fiber (Melty 4080 manufactured by Unitika Ltd.) having a polyethylene terephthalate polymer having a melting point of 260 ° C. as a core component. After blending at a weight ratio of 20% by weight of the heat-fusible fiber to a non-woven web with a parallel card, the sheath component is melted by passing through a dryer kept at 125 ° C. The sheet was fixed to obtain a sheet having a basis weight of 100 g / m ² . Next, phosphoric acid is applied to the above-mentioned sheet-like material by a spray coating method, a clearance is provided in a thermal pressure welding device having a pair of two flat rolls, and the sheet is passed through the thermal pressure welding device at a temperature of 130 ° C. 0.4
A 5 mm sheet was used.

The obtained sheet is sized 15 cm × 1
After producing a 5 cm x 15 cm corrugated filter, it was incorporated into a wind tunnel tester, the concentration of ammonia gas on the filter inlet side was adjusted to a constant 1 ppm, and the linear velocity was 0.5 m
The air outlet test was carried out at a rate of 1 hour / second to measure the outlet concentration of the filter.

Example 2 The same procedure as in Example 1 was carried out except that the activated carbon fibers were changed to those having a pore volume of 1.0 ml / g and an average pore diameter of 3.0 nm, and a basis weight of 80 g / m ² , After forming a sheet having a thickness of 0.3 mm, a filter was prepared, and the same test as in Example 1 was performed to evaluate the gas removing ability of the filter.

Comparative Example 1 The same procedure as in Example 1 was repeated except that the activated carbon fiber was changed to one having a pore volume of 0.5 ml / g and an average pore diameter of 1.9 nm, and the basis weight was 80 g / m ² , After forming a sheet having a thickness of 0.55 mm, a filter was prepared, and the same test as in Example 1 was performed to evaluate the gas removing ability of the filter.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the activated carbon fiber was changed to one having a pore volume of 0.3 ml / g and an average pore diameter of 1.7 nm, and the basis weight was 100 g / m ² , After forming a sheet having a thickness of 0.7 mm, a filter was prepared, and the same test as in Example 1 was performed to evaluate the gas removing ability of the filter.
Table 1 also shows the properties of the sheet-like materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2, and the evaluation results of the gas removal ability of the filter.

[0022]

[Table 1]

As is clear from Table 1, the sheet-like materials obtained in Examples 1 and 2 are thinner than those of Comparative Examples 1 and 2 and have a larger amount of retained phosphoric acid. The filter has a longer removal time of 90% of the ammonia gas than the filters of Nos. 2 and 3, and has a high ability to remove odorous gas.

[0024]

According to the present invention, if the sheet-like material for removing odorous gas of the present invention is formed and processed, it has a high ability to remove odorous gas,
In addition, a filter having a low pressure loss can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a corrugated filter formed by the sheet-like material for removing malodorous gas of the present invention.

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Claims (1)

[Claims] 1. An activated carbon fiber having a pore volume of 0.7 ml / g or more and an average pore diameter of 2.0 nm or more and a heat-fusible fiber, and the composition ratio is 50:50 by weight. 9
0:10, the sheet thickness is 0.5 mm or less, and phosphoric acid in the sheet is 25 g / m ^2.
A sheet-like material for removing odorous gas, which is held as described above.