JPH0432684B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an adsorbent sheet containing activated carbon fibers.

[Conventional technology]

Powdered and granular activated carbon is generally used as an adsorbent for various substances in gases and solutions, but it has also been proposed that activated carbon be made into fibers to form filters that allow gases and solutions to easily pass through. has been done.

[Problem that the invention seeks to solve]

However, powdered or granular activated carbon may be mixed into gas or solutions during adsorption, so adsorption is usually performed within a limited volume using a filter, etc. There are drawbacks, such as the fact that it takes a lot of pressure to pump it inside. In addition, activated carbon fibers have been improved with respect to the above-mentioned drawbacks, but their adsorption power is significantly reduced due to the adhesion of mist and dust such as oil and resin in the gas, and the adsorption power of activated carbon fibers is significantly reduced due to the adhesion of oil droplets and dust in the solution. There was a drawback that suspended matter adhered to the product. Additionally, activated carbon fibers have the disadvantage of relatively poor adsorption power for low molecular weight ionic substances such as hydrogen halide, hydrogen sulfide, and ammonia in gases, and chlorine ions, nitrate ions, nitrite ions, and ammonia ions in solutions. Ta.

[Means for solving problems]

In view of the current situation, the present invention has been developed to form a nonwoven fabric made of activated carbon fibers on one or both sides of which the bonding points are fused and reinforced with composite fibers containing a high melting point synthetic resin as a core component and a low melting point synthetic resin as a sheath component. , to prevent non-woven fabrics consisting only of high-melting point synthetic fibers, or non-woven fabrics made of high-melting point synthetic fibers mixed with composite fibers having a high-melting point resin as a core component and a low-melting point synthetic resin as a sheath component, from separating due to fusing, entanglement, etc. The nonwoven fabric is laminated, and at least one of the nonwoven fabrics is mixed with ion exchange fibers so that they do not separate.
It is an adsorbent sheet that is characterized by its properties.

[Effect]

Since the adsorbent sheet of the present invention has fibrous activated carbon, it has excellent adsorption properties for various substances, is porous and has excellent permeability, and the activated carbon is firmly retained and lost when mixed with gases, solutions, etc. There's nothing to do. In addition, since the activated carbon is protected on at least one side by a synthetic fiber non-woven fabric, the synthetic fiber non-woven fabric removes dust and mist from gases and solutions, thereby rapidly reducing the unexpected adsorption power of the activated carbon due to dust and mist. can be avoided. Furthermore, it adsorbs polar substances that activated carbon fibers do not adsorb, such as ammonia in gas and chlorine ions and ammonia ions in solutions, making it possible to remove a wide range of substances.

〔Example〕

Hereinafter, the present invention will be explained in detail according to illustrated embodiments.

In FIG. 1, reference numeral 1 is an adsorbent sheet in which composite fiber-containing synthetic fiber nonwoven fabrics 2 and 4 are laminated on both sides of an activated carbon fiber nonwoven fabric 3 and fused by heating.

The activated carbon fiber nonwoven fabric 3 is made by mixing activated carbon fibers with composite fibers having a high melting point synthetic resin as a core and a low melting point synthetic resin as a sheath, melting the low melting point synthetic resin, and fusing the contact points with the activated carbon fibers. It is. Here, the activated carbon fiber is made by polymerizing coal tar to form an isotropic spinning pitch, which is then melt-spun to form a pitch yarn, which is then treated at high temperature to make it infusible, and then activated in an oxidizing gas. The above-mentioned infusibility process develops a network structure, and the activation process in an oxidizing gas atmosphere creates countless pores (micropores) with pore diameters in the angstrom unit on the surface. This results in a significant increase in surface area. Adsorption of each substance is performed by the pores, and the pore size determines the adsorbed substance, and the number, pore size, and depth determine the adsorption amount. The pore diameter, number, depth, etc. of the pores vary depending on the raw materials and manufacturing conditions, but 500~
A specific surface area of 2500 m ² /g is desirable. It is desirable that the activated carbon fiber has a small diameter, for example,
15-20 microns is optimal. Activated carbon fibers may be long fibers or short fibers, and in the case of long fibers, a large number of extruded fibers are taken up by an air stream and randomly accumulated on a conveyor belt to form a nonwoven fabric. In this case, it is formed by cutting extruded fibers into appropriate lengths.

The core components of the composite fibers to be mixed with activated carbon fibers include polyester, polypropylene,
Various synthetic resins such as polyamide are used, and the synthetic resin of the sheath component has at least a higher content than the synthetic resin of the core component.
It is desirable to use one with a melting point of 40°C or less. The synthetic resins of the core component and sheath component are preferably of the same type. The synthetic resins for the core component and sheath component are preferably of the same type, but a combination of different synthetic resins may be used as long as they have compatibility.

When the composite fiber is made of polyester, the core component is polyester with a softening point of 240℃ or higher,
It is desirable to use a composite fiber whose sheath component is polyester having a softening point of 100 to 150°C. Furthermore, in detail, the core component is mainly polyethylene terephthalate, and the sheath component is one dibasic acid or its derivative, one glycol, and one or more dibasic acids or glycols different from these. An example of the latter is a copolyester containing terephthalic acid, isophthalic acid, and ethylene glycol as main components. In addition to the above, polyethylene, polypropylene, etc. can also be used as the sheath component. When using polyester as a composite fiber, bulkiness,
Excellent elastic recovery.

Other composite fibers have a core component of polypropylene and a sheath component of polyethylene, polystyrene,
Ethylene propylene copolymers and the like are also preferred.

The fineness of the composite fiber is preferably 10 deniers or less, but is not limited to this. The fineness of the core component of the composite fiber is preferably 1/2 to 1/6 of the fineness of the entire composite fiber. When the conjugate fiber is mixed into a card or the like described below, it is desirable that the fiber be cut into 50 to 150 mm pieces and crimped to improve blending and facilitate fusing with activated carbon fibers and the like.

Activated carbon fibers and composite fibers are supplied to cards etc.
The fibers are opened and mixed to form a web, which is heated to a temperature between the respective melting points of the sheath component and the core component of the composite fiber through a hot air oven, etc., and the sheath component of the composite fiber is bonded to the activated carbon fiber. be fused to. As a result, an activated carbon fiber nonwoven fabric having excellent strength, bulkiness, elastic recovery, etc. can be obtained.

A synthetic fiber nonwoven fabric is laminated on one or both sides of the obtained activated carbon fiber nonwoven fabric. The synthetic fiber nonwoven fabric used here has fibers made of various synthetic resins such as polyester, polyamide, and polypropylene, and a high melting point synthetic resin as a core component. , composite fibers having a low melting point synthetic resin as a sheath component are mixed in a card or the like, and the composite fibers are almost the same as those used in the case of the activated carbon fiber nonwoven fabric. Both the activated carbon fiber nonwoven fabric and the synthetic fiber nonwoven fabric include composite fibers with a low melting point synthetic resin sheath.
Both can be fused together by heating during lamination.

Note that at least one of the activated carbon fiber nonwoven fabric 3 and the synthetic fiber nonwoven fabrics 2 and 4 forming the adsorbent sheet 1 is mixed with ion exchange fiber. Here, ion-exchange fibers are fibers containing ion-exchange groups alone, fibers mixed with reinforcing fibers, or composite fibers with ion-exchange group-containing fibers as a sheath and reinforcing fibers as a core. It's good as well.

Here, the ion exchange group refers to an anion exchange group,
Cation exchange groups, chelate groups, etc., and anion exchange groups can be obtained by treating haloalkylated threads with tertiary bases such as trimethylamine and dimethylaminoethanol, and secondary or lower amines such as isopropylamine and diethylamine. Examples of basic anion exchange groups and cation exchange groups include chlorosulfonic acid, strong acid cation exchange groups obtained by sulfonation with concentrated sulfuric acid, weakly acidic cation exchange groups such as carboxylic acid, and chelate groups such as iminodiamine. Examples include, but are not limited to, chelate-forming functional groups such as acetate group and iminodipropionic acid. In addition, various polymers such as ring-containing vinyl polymers, polyvinylpyridine, acrylic acid polymers, and methacrylic acid polymers are used as polymeric substances into which ion exchange groups can be introduced.

The resulting adsorbent sheet is laminated with synthetic fiber non-woven fabric, which uses the affinity of the synthetic fibers to remove dust, mist, etc. that reduce the adsorption power of activated carbon, increasing the sustainability of the adsorption power. It is possible to prevent the accidental detachment of carbon and the adhesion of dirt due to direct contact with activated carbon. It is also used to remove acidic gases such as hydrogen sulfide, hydrogen halides, and sulfur dioxide gas, basic gases such as ammonia, and remove chromic acid, amines, and pigments.

The adsorbent sheet according to the present invention can be used for filters for cleaning air in factories, etc., as well as medical products such as masks, medical sheets, medical suits, base fabrics for ships, bandages, covers, diapers, garbage for garbage disposal, etc. It is used for various purposes such as bags, curtains, gloves, and fire evacuation equipment.

Furthermore, it is also possible to incorporate various materials in addition to the above. For example, if ultra-fine copper fibers of about 20 to 40 μΦ are mixed into one of the layers, the sterilizing property and antistatic effect will be improved, and the water absorption property will be improved. If you mix fiber,
Water absorption is improved.

In FIG. 2, the adsorbent sheet 1' is made by laminating synthetic fiber nonwoven fabrics 2' and 4' that do not contain composite fibers on both sides of an activated carbon fiber nonwoven fabric 3, and applying needle punching to entangle the fibers so that they do not separate. being done. The activated carbon fiber nonwoven fabric 3 is the same as that shown in FIG. 1, and the synthetic fiber nonwoven fabrics 2' and 4' are the same synthetic fiber nonwoven fabrics as shown in FIG. 1 except that they do not contain composite fibers, and at least one of them contains ion exchange. fibers are mixed.

In the above figures, the same synthetic fiber non-woven fabric is used for laminating on both sides of the activated carbon fiber non-woven fabric 3, but one side is a synthetic fiber containing composite fibers, and the other side is a synthetic fiber containing no composite fibers. Alternatively, a synthetic fiber nonwoven fabric containing or not containing composite fibers may be used on only one side of the activated carbon fiber nonwoven fabric 3. In this case, when composite fibers are used, the bonding with the activated carbon fibers can be performed by fusion, and when composite fibers are not used, the binding with the activated carbon fibers can be performed by needle punching. In this case as well, it is important that at least one layer contains ion exchange fibers.
This is the same as in the case of FIG.

〔Effect of the invention〕

As is clear from the above description, the present invention has excellent adsorption and permeability to various substances, and the activated carbon is firmly retained and will not be lost. It is possible to achieve excellent practical effects, such as preventing a sudden drop in the adsorption power of activated carbon fibers due to dust, and being able to adsorb ionic substances and polar substances that cannot be adsorbed by activated carbon fibers.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a side view of the first embodiment, and FIG. 2 is a side view of another embodiment. 1: Adsorbent sheet, 2, 4: Synthetic fiber nonwoven fabric,
3: Activated carbon fiber nonwoven fabric.

Claims (1)

[Claims] 1 A nonwoven fabric made only of high melting point synthetic fibers on one or both sides of an activated carbon fiber nonwoven fabric whose joint points are fused and reinforced with composite fibers having a high melting point synthetic resin as a core component and a low melting point synthetic resin as a sheath component. Alternatively, a nonwoven fabric made by mixing high melting point synthetic fibers with composite fibers having a high melting point resin as a core component and a low melting point synthetic resin as a sheath component is laminated so as not to separate due to fusion and entanglement of the fibers. An adsorbent sheet characterized in that at least one of the sheets is mixed with ion exchange fibers so that they do not separate.