JP2003313780A - Water repellent fibrous activated carbon sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fibrous activated carbon sheet having water repellent property and exhibiting a high gas barrier property even on becoming wet with water, sweat, and the like. <P>SOLUTION: This fibrous activated carbon sheet obtained by carbonizing and activating a fibrous polymer precursor is characterized by having ≥2 water repellency. The fibrous polymer precursor is a phenolic fiber, and the sheet is characterized by having 25 g/m<SP>2</SP>toluene adsorbing performance, 50-250 g/m<SP>2</SP>absolutely dried unit weight and 500-3,000 m<SP>2</SP>/g specific surface area measured by the BET method. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet of fibrous activated carbon obtained by subjecting a sheet of carbonizable raw material organic fiber to carbonization and activation treatment, and comprising a lamination process. The present invention relates to a fibrous activated carbon sheet which is excellent in processability, is durable against tearing and bending, has good handleability, and has excellent organic gas adsorption performance. More particularly, the present invention relates to medical supplies such as masks, deodorizing pads, and deodorizing sheets, protective clothing for protecting the body from harmful gases, and fibrous activated carbon sheets used for various air purifiers. In addition, when this fibrous activated carbon sheet is used alone or laminated with other sheet materials for use in medical supplies, protective clothing, filters, etc., it has high gas barrier properties even when wet with water or sweat. The present invention relates to a fibrous activated carbon sheet having the same. [0002] Hitherto, it has been proposed to obtain a fibrous activated carbon by subjecting a carbonizable raw material organic fiber to a carbonizing treatment and an activation treatment. In addition, as a method for obtaining a sheet-like fibrous activated carbon in which the fibrous activated carbon forms a sheet shape, a method in which the raw organic fibers are formed into a nonwoven fabric such as a felt or a woven or knitted fabric, followed by carbonization and activation treatment or a raw organic A method of carbonizing and activating the fiber to obtain a fibrous activated carbon and then processing it into a nonwoven fabric such as a felt. [0003] These fibrous activated carbons are utilized for various applications because of their high gas adsorption / desorption speed and very large adsorption performance due to the originally developed micropore structure of micropores. However, when these fibrous activated carbon sheets are wetted by moisture condensation in the air, sweat, or the like, they cannot exhibit sufficient practical performance when used as a filter or protective clothing. [0004] The present invention seeks to solve the above-mentioned problems in the prior art. That is, an object of the present invention is to provide a fibrous activated carbon sheet having a large adsorption performance for an organic solvent gas per unit area and having water repellency. 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 provides a fibrous activated carbon sheet obtained by forming a fibrous polymer precursor into a sheet, and then carbonizing and activating the fibrous polymer precursor, wherein the fiber has a water repellency of 2 or more, more preferably 4 or more. Activated carbon sheet. [0006] The fibrous activated carbon sheet is used as various filters and elements for adsorbing gases of various organic solvents because of its excellent flexibility. As described above, in the sheet forming method, the raw material organic fibers were formed into a nonwoven fabric or a woven shape such as felt, and then a method of carbonizing and activating was performed, and the raw material organic fibers were carbonized and activated to obtain fibrous activated carbon. A method of processing into a nonwoven fabric such as felt later can be cited, but a knitted fibrous activated carbon sheet is excellent in terms of flexibility and processability. It is particularly advantageous that the sheet is knitted because of its flexibility, especially when the sheet itself is handled in a place with movement, such as lamination with other fiber materials or protective clothing. For the step of obtaining the fibrous activated carbon knit, a method of knitting the fibrous polymer precursor in advance into a knit, then carbonizing and activating it to form an activated carbon knit is good. Because of its low strength, it is not practically possible in industry. The adsorption performance of the activated carbon sheet is JIS
K1377 “Test method for fibrous activated carbon”, 25 g / m ² or more (25 ° C., 1
/ 10 dilution), preferably 40 g / m ² or more. If the amount is lower than the above-mentioned amount, practical performance cannot be sufficiently exhibited when used as a filter or protective clothing. When a fibrous activated carbon sheet is processed according to the purpose, for example, when it is laminated with another fiber aggregate such as a woven or knitted fabric or a nonwoven fabric, mechanical stress is applied to the fibrous activated carbon sheet when it is industrially processed. In addition, tears and tears occur. In order to prevent this, at least JIS L101
The tensile strength according to the method described in No. 8 is 1.0N or more, JIS
L1096 The tear strength (trapezoid method) described in 8.15.4 needs to be 1.0 N or more, preferably 2.5 N or more. If it is less than this, productivity is greatly reduced when laminating and other processes for commercialization are performed, and the process becomes impractical. In order to obtain such a fibrous activated carbon sheet having a large tear strength, it is desirable that the precursor fiber is a phenolic fiber. Other known precursor fibers of fibrous activated carbon include cellulose-based, pitch-based and PAN-based fibers. When cellulosic fibers are used as the whole precursor, fibrous activated carbon having a specific surface area that exhibits sufficient adsorption performance by carbonization and activation can be obtained, but the yield is low, and the shrinkage is large, so the rigidity is high, and the sheet , Especially low tear strength. When the PAN fiber is used as the precursor fiber, a fiber having a relatively high sheet strength can be obtained, but it is difficult to obtain a fibrous activated carbon having a large adsorption performance. When pitch-based fibers are used, an intermediate strength between cellulose-based and PAN-based fibers and adsorption performance can be obtained, but both properties are not necessarily satisfied. DETAILED DESCRIPTION OF THE INVENTION In the present invention, the fibrous activated carbon sheet is reduced in mechanical strength by being carbonized and activated. In particular, when the tear strength is extremely reduced, it is disadvantageous because it leads to breakage during post-processing or use. Therefore, when using activated carbon as a raw material sheet, it can be obtained by performing a batch or continuous carbonization and activation process.However, it is necessary to obtain uniform dough characteristics and adsorption performance of the fibrous activated carbon sheet and to improve industrial productivity. In consideration of the above, it is preferable to continuously perform carbonization and activation.
The raw material sheet is carbonized in an inert atmosphere at a temperature of 350 ° C. or more and 1000 ° C. or less, and then activated in an active atmosphere containing steam, oxygen, carbon dioxide, etc. which reacts with carbon at a temperature of 500 ° C. or more and 1000 ° C. or less. I do. In some cases, carbonization and activation can be performed simultaneously by controlling the atmospheric conditions. In addition, when the activation treatment, that is, the highest temperature when performing the activated carbonization is set to 1000 ° C. or more, wrinkles may be generated due to abnormal shrinkage or the like,
It is preferable that the maximum temperature be 1000 ° C. or lower.
Thereby, a fibrous activated carbon sheet having a specific surface area of 500 to 3000 m ² / g is obtained. The basis weight of the obtained fibrous activated carbon sheet is 50 to 250 g / m ² , preferably 100 to 150 g / m ² .
g / m ² is good. If it is 50 g / m ² or less, the strength of the activated carbon sheet is low, and if it is 250 g / m ² or more, there is a problem that air permeability becomes poor. As a method for imparting water repellency to the fibrous activated carbon sheet, spraying with a spray or impregnation may be considered, but impregnation is preferred in view of uniformity. The water repellent is not particularly limited, such as fluororesin, silicone resin and wax.
The amount of impregnation may be 0.1 to 15, preferably 0.5 to 5 wt% as a solid content of the water repellent. 0.1wt impregnation amount
% Or less, the water repellency is low, and if it is 15 wt% or more, the performance of the activated carbon is reduced. (Examples) The present invention will be described below in detail based on examples. However, the following embodiments do not limit the present invention, and all modifications and implementations without departing from the gist of the preceding and following descriptions are included in the technical scope of the present invention. In addition, the measuring method of each characteristic value of a sheet is as follows.
The absolute dry mass, basis weight, and thickness of the sheet are JIS L
1018, and the toluene adsorption performance of the fibrous activated carbon conformed to JIS K1277. The water repellency of the sheet conformed to JIS L1092 6.2. Example 1 A phenolic fiber having a single fiber fineness of 2.2 dtex and a thread-like fineness of 295 dtex was used.
Milled knitted fabric was knitted with a two-gauge double-sided circular knitting machine.
This sheet has a basis weight of 225 g / m ² and a thickness of 1.65 mm.
Set to. This sheet is carbonized from an ordinary temperature to 890 ° C. for 30 minutes in an inert atmosphere, and then 12 wt% of steam
Was activated at a temperature of 890 ° C. for 90 minutes in an atmosphere containing The obtained knitted fibrous activated carbon sheet had an absolute dry mass of 120 g / m ² , a thickness of 1.05 mm, and a toluene adsorption performance of 56 g / m ² . This fibrous activated carbon sheet was treated with 3% by weight of a fluorine-based water repellent (Asahi Kaat Co., Ltd. AG970), 0.3% by weight of a crosslinking agent (Sumitomo Chemical Co., Ltd. Sumitex Resin M-3), and 0.1wt%
The pad was dried in a processing bath containing the catalyst (Sumitomo Chemical Industry Co., Ltd., Sumitex Accelerator ACX), fixed at 170 ° C., and impregnated with 0.5% by weight of a water-repellent agent solid content. (Comparative Example 1) The same fibrous activated carbon sheet as in Example 1 but not subjected to the water-repellent treatment was used as Comparative Example 1. Table 1 shows the water repellency of the materials obtained in Example 1 and Comparative Example 1. The materials obtained in Example 1 and Comparative Example 1 were immersed in pure water for 5 minutes, taken out and dehydrated. Table 2 shows the water content of pure water with respect to the material at this time. This material was set in a container in an incubator set at 25 ° C. as shown in FIG. 1, a pot containing 10 μL of toluene was placed in the container, and the gas concentration on the downstream side was sampled at regular intervals by a syringe. did. At this time, the result measured by gas chromatography is shown in FIG. [Table 1] [Table 2] As described above, by treating the fibrous activated carbon sheet with water repellency as in Example 1, the fibrous activated carbon has high gas barrier properties even when it is wet with water, sweat, etc. In Comparative Example 1 which was not subjected to the water treatment, the gas barrier property was reduced. As described above, the present invention relates to a fibrous activated carbon sheet having a high adsorption performance to an organic solvent gas per unit area obtained by carbonizing and activating a fibrous polymer precursor. By performing a water-repellent treatment, it is possible to provide a fibrous activated carbon sheet having excellent gas barrier properties even when wet with water or sweat.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a test container for evaluating gas barrier properties. FIG. 2 is a graph showing the results obtained when evaluating gas barrier properties. [Description of Signs] A: Fibrous activated carbon sheet B: Glass container C: Glass pot D: Toluene (liquid) E: Silicon cap

Claims (1)

1. A fibrous activated carbon sheet having a water repellency of 2 or more according to JIS L1092 6.2.