JPH09285531A - Adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide adsorbent of low loss and high adsorption capability. SOLUTION: On a surface of a mesh net of favorable ventilation property and a contact surface of an inner organization with outer air, a binder layer comprising polymer-based adhesive agent without including latex, emulsion or solvent is formed, active carbon grain is applied to the binder layer, at least a part of the grain surface is kept in an exposed condition, and in addition, this binder coating layer is formed on the surface of a mesh net. This net may further be molded in pleats for use. In this adsorbent, the active coal grain is uniformly dispersed on a base plate of the mesh net in the condition of a high porosity between grains, and held in the condition where the surface of the active coal grain is exposed to achieve high adsorption speed and large adsorption capacity. In addition, as this is in the form of a mesh net of favorable ventilation, pressure loss is extremely low, and it is suitable for usage in a low gas fluidity atmosphere or a large blow quantity condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an adsorbent which is used mainly for removing a trace amount of malodorous components in air and has a fast adsorption rate and excellent handleability. The main fields of application are filter elements used for home or automobile air conditioners and air cleaners, which have the characteristics of low pressure loss and long life, even when air is flowed at high speed.
A high degree of purification can be achieved with a pass.

[0002]

2. Description of the Related Art Conventionally, activated carbon has been widely used as an adsorbent for trace components, but the shape is generally powder or granular, and it is not always easy to handle. Therefore, an adsorbent in which an emulsion in which fine powder of activated carbon is dispersed is impregnated in a net material, a woven fabric, a non-woven fabric or the like, or an adsorbent in which activated carbon particles are fixed in a porous material such as a net material, a foam material or a non-woven fabric is tried. There is. These adsorbents are convenient to handle because they do not generate dust unlike powders, and also have the advantage of low resistance because the gas can freely flow through the voids in the porous material.

However, these types of adsorbents that have been conventionally produced have the disadvantage that only a small part of their adsorption capacity can be used because the surface of the activated carbon contained in the porous material is coated with a binder. It had been. This is because when the activated carbon is adhered to the internal structure of the porous material, if the activated carbon and the binder are mixed and adhered, it is inevitable that most of the surface of the activated carbon particles is covered with the binder layer.

There is also a method of preparing a polyurethane foam by mixing adsorbent particles with a prepolymer. In this case, if a large amount of activated carbon particles are mixed, the foamability of polyurethane foam will be suppressed, and a considerably large part of the surface of the activated carbon particles will be covered with polyurethane resin, or the pores will be clogged and the adsorption capacity will be increased. Is significantly reduced.

In order to solve these problems, a method of forming adsorbent particles after forming a binder layer on the surface of the foamed polyurethane molding and on the contact surface of the internal structure with the outside air is also disclosed. In Japanese Patent Publication No. 4-35201,
A method is disclosed in which a urethane-based prepolymer is applied on the surface and internal structure of a foamed polyurethane molded article, and then adsorbent particles are sprayed and attached.

The adsorbent obtained by impregnating an emulsion in which fine powder of activated carbon is dispersed in a mesh net, a woven fabric or a non-woven fabric, etc., has a reduced pressure loss because the surface of the fine powder is coated with a thin film of the emulsion. However, there is a demerit that sufficient adsorption performance cannot be obtained.

[0007]

In view of these problems, the present invention uses a mesh net having good air permeability as a base material of the adsorbent, and a part of the particle surface is exposed to this net. The present invention aims to develop and provide an adsorbent having a low pressure loss and a high adsorptivity by adhering activated carbon particles in the existing state.

[0008]

The inventors of the present invention have found that when a gas in a severe turbulent air flow passes through an adsorbent layer having a low packing density, the contact efficiency between the gas and the adsorbent is remarkably enhanced and the malodorous gas is removed. It was noted that the structure is suitable for gas processing with low pressure loss and high air volume because the performance is improved. Therefore, we researched a structure that uses a mesh net with good air permeability as a base material and holds the adsorbent particles inside as if they were floating in the space, reducing the degree of impeding air permeability as much as possible. . As a result, it was found that by adhering the activated carbon particles to the well-ventilated mesh net with a binder, the adsorbent particles can have a suitable porosity inside the adsorbent. Based on this, the present invention has been reached.

That is, a binder layer made of a polymer adhesive containing no latex or emulsion or a solvent is formed on the surface of the mesh net having good air permeability and the contact surface of the internal tissue with the outside air, and the binder layer is formed on the binder layer. It is an adsorbent in which activated carbon particles are adhered and held so that at least a part of the particle surface is exposed. Alternatively, an adsorbent obtained by forming a coating layer of these binders on the surface of a mesh net is suitable for an air conditioner or an air purifier to be mounted on an automobile.

In addition, as described above, the mesh net supporting the activated carbon particles in a pleated form, or the mesh net and the electret-treated non-woven fabric, a conductive sheet, a magnetic sheet or an oxidation catalytic sheet is used. The present invention also includes an adsorbent formed by stacking one or more layers to form a pleat shape. Furthermore, the surface of the net and the internal structure of the net are made to pass through the fluidized bed of activated carbon particles after forming a binder layer on the surface of the mesh having good air permeability and the contact surface of the internal structure with the outside air. Is a method for producing an adsorbent, characterized in that activated carbon particles are attached to the contact surface with the outside air, and at least a part of the particle surface is held exposed.

The present invention will be described in detail below.

The adsorbent of the present invention needs to use a mesh net having good air permeability as a base material. The material of the fibers forming the net is not particularly limited. For example, polyethylene, polypropylene, polyurethane, nylon, polyester, polyvinyl chloride, polyvinylidene chloride, fluororesin, vinylon, polyacrylic polymer, cellulose acetate, synthetic fibers such as Promix, semi-synthetic fibers, other rayon, cotton, hemp, Natural fibers such as silk or inorganic fibers can also be used. Furthermore, the material of the net is not limited to fiber,
A mesh net woven with a thin aluminum wire may be used.

The structure of the reticulated net is not particularly limited, and may be any coarse knitting so that air permeability is good. After roughly knitting the fibers, the adhesive or the partial melting of the fibers is performed. Alternatively, a structure in which the stitches are joined and fixed by a mechanical method may be used. In particular, the base material used in the present invention is a base material obtained by fusing the intersecting portions of fibers during the molding of the net and enhancing the rupture and tear strength of the net, since the structural robustness is increased even if the stitches are coarse. Is preferred as

Further, the base material of the reticulated net has a structure in which wrinkles are provided in one direction or in a plurality of directions by pleating, and the present invention also includes the use of supporting activated carbon particles. The thickness of the fiber of the base material is not particularly limited, but a fiber of 20 to 200 denier is preferable in order to obtain a mesh net having coarse knitting and high air permeability.

The cross-sectional shape of the fiber of the base material is usually circular, but a fiber having a so-called irregular cross section other than the circular shape or a split yarn having a flat cross section can also be used, and the structure should be selected. As a result, the ventilation resistance is low, and it becomes possible to firmly hold a large amount of activated carbon particles on the surface of the fiber, which may further improve the adsorptivity.

The activated carbon contained in the adsorbent of the present invention is
Generally, a carbon material having a large surface area of several hundred square meters per gram or more and having a high adsorptivity can be widely used. As a raw material for activated carbon, a charcoal such as palm shell or wood is usually used, or coal is used. Also, the activation method may be obtained by steam or carbon dioxide at a high temperature or by any method such as treatment with zinc chloride, phosphoric acid or concentrated sulfuric acid.

Activated carbon is a peculiar substance having extremely excellent adsorptivity as a non-polar adsorbent, and is known to exhibit high adsorptivity for almost all gaseous or liquid substances. The adsorbent of the present invention also utilizes such characteristics of activated carbon.

The size of the activated carbon particles carried on the reticulated net is not particularly limited, and the effect can be recognized even when particles having a wide range of particle sizes are used. However, in order to keep the adsorption capacity high and suppress the pressure loss, the average particle size of the particles is preferably 20 mesh or less and 100 mesh or more.

In the present invention, in order to adhere the activated carbon particles to the mesh net, it is necessary to use a latex or emulsion or a solvent-free polymer adhesive. Since it is preferable that the activated carbon particles are less likely to be clogged with pores, a latex or emulsion having a large solid content is suitable, and the solid content is preferably 30% or more, more preferably 50% or more.

Here, the latex or emulsion means a state in which rubber particles or polymer particles having adhesiveness are dispersed in water as a dispersion medium. Examples of the latex include various synthetic rubber latexes such as SBR, chloroprene, and nitrile rubber, and the emulsions include acrylic emulsions obtained by copolymerizing acrylic ester and acrylic acid or methacrylic ester, and ethylene-vinyl acetate copolymers. Polymerized resin emulsion or vinyl acetate resin emulsion can be used.

The solvent-free polymer-based adhesive is a prepolymer having adhesiveness and containing no organic solvent or water. The adhesive of the present invention is preferably a synthetic rubber-based substance, for example, NCO excess. Urethane type prepolymer of, more preferably MDI (methylene diisocyanate)
Base urethane prepolymers are preferred. MDI-based prepolymers are preferable because they are less likely to generate free isocyanate than TDI (tolylene diisocyanate) -based prepolymers and have less adsorptivity to adsorbent particles.

In the case of using an NCO-excessive urethane prepolymer, a small amount of an organic solvent may be added in order to adjust the viscosity, and after impregnating or coating the sheet-like fabric, it is mostly dried by warm air or the like. Remove the organic solvent of
After forming a binder layer on the surface of the woven fabric and the fiber surface of the internal structure, activated carbon particles may be attached thereon.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION It is necessary to form a binder layer made of the above-mentioned binder on the surface of the mesh net which is the base material of the adsorbent of the present invention and the contact surface of the internal structure with the outside air. In order to attach the binder to the surface of the mesh net and the contact surface of the internal tissue with the outside air, after dipping this net in a bath filled with a binder such as latex or emulsion, a method of removing excess binder with a roll, Alternatively, there is a method of coating the surface with a spray or a coater, and then squeezing with a roll to allow the binder adhered to penetrate into the inside of the tissue. Further, the binder layer can be formed on the surface of the woven fabric and on the contact surface of the inside fiber structure with the outside air by removing the film formed between the entangled fibers by air blowing.

In order to adhere the activated carbon particles to the surface of the mesh net on which the binder layer is formed and the contact surface of the internal structure with the outside air, a fluidized bed passage method, a powder spray method, a sieve drop method or the like is used. The method can be adopted.

In the fluidized bed passage method, a reticulated net having a binder layer formed inside the tissue is passed through a fluidized bed of activated carbon particles, usually with the net being horizontal, so that the particles are introduced inside the tissue of the net. It is a method of permeating. The fluidized bed is formed by blowing gas through the lower dispersion plate into a tank filled with activated carbon particles to a certain depth to form a fluidized bed.
The gas blowing velocity is in a gas velocity region relatively close to the minimum fluidization velocity, and even when the gas is passed through the mesh net, the particles can be uniformly penetrated into the inside of the net structure.

According to the other methods, most of the particles tend to adhere only to the surface of the mesh net, and it is difficult to permeate the inside of the net sufficiently to adhere it. However, in the fluidized bed passage method, the fluidized state is adjusted to the particle size of the activated carbon particles, the gas injection rate is appropriately adjusted, and the residence time in the fluidized bed of the mesh net is further adjusted to the internal structure of the net. Since the activated carbon particles can be attached uniformly,
It is most suitable for the particle adhering step of the adsorbent of the present invention.

In the case of the powder spray method or the sieve dropping method, the reticulated net is appropriately inverted and the activated carbon particles are sprayed from both sides of the net, or the particles are dropped to attach the particles to the inside of the tissue. Can be made. Further, by virtue of vibrating this net after the step of attaching the activated carbon particles to the net or after attaching it,
Entry of particles into the tissue and adhesion to the binder layer can be promoted.

After the activated carbon particles are attached to the mesh net, the particles can be firmly adhered to the binder layer by gently pressing the net through one or more sets of pinch rolls. At this time, a heating roll may be used for a part or all of the roll to promote the adhesion.

The activated carbon particles contained in the reticulated net obtained as described above are once adhered to the surface of the binder layer having the internal structure by a fluidized bed passage method or the like, and then firmly bonded by a heating and pressure bonding step. Because it is glued to
A large part of the particle surface is exposed. In the present invention, "a state in which at least a part of the particle surface is exposed" refers to such a state, as can be seen from the state in which the activated carbon particles are bonded to the binder layer,
Substantially most of the particle surface is kept exposed. This is one of the most important features of the structure of the adsorbent of the present invention.

Conventionally, when supporting activated carbon particles on a carrier,
A method in which the particles are mainly mixed with a binder such as latex or emulsion and then applied is used. In this method, since the surface of the activated carbon particles is coated with the binder, it is inevitable that the adsorptivity of the activated carbon is hindered. However, as described above, since the surface of most of the activated carbon particles is exposed in the reticulated net obtained by the present invention, the adsorption capacity of each activated carbon particle is large and the adsorption rate is high. Moreover, since the mesh net has a coarse structure as a whole, the cross-sectional area of the gas flow passage is quite large, and therefore the pressure loss is low and the gas flows at high speed.
The gas becomes a state of intense turbulent flow inside the adsorbent.

After the activated carbon particles are attached to the mesh net, the clearance of the pinch roll used for firmly adhering the particles to the binder layer can be appropriately set, but is preferably 50 to 80% of the sheet thickness. . Further, when the activated carbon particles are adhered to the polyurethane-based prepolymer layer, the adhesive force can be further improved by heating with steam.

The particles adhered to the surface of the mesh net are
Since it is likely to come off during use due to friction or the like, a latex or emulsion or a polymer-based adhesive containing no solvent can be further applied to the surface of the net to prevent this. Here, the surface means a portion which is easily rubbed by coming into contact with an external object.

The type of binder does not necessarily have to be the same as that impregnated inside the structure of the mesh net,
Different types of binders may be used in consideration of their suitability. The surface of the activated carbon particles coated with the binder is less coated because it is coated with a thin binder layer, but the ratio of the particles on the coated surface is a part of the whole, so the total amount of the adsorbent is There is little deterioration in function.

Further, the adsorbent of the present invention can be used in a single layer, but it is also possible to use a plurality of laminated layers or pleats. In the case of processing into pleats, a mesh net of an adsorbent may be overlaid with paper, a nonwoven fabric, an electret nonwoven fabric, a conductive sheet, a magnetic sheet, an oxidation catalyst sheet or the like.

The adsorbent of the present invention has activated carbon particles adhered to the surface of the mesh net, which is a base material having good air permeability, and the contact surface of the internal structure with the outside air, and has a very low pressure loss. It is also possible to use the gas in an atmosphere with poor fluidity or in a state of high air flow. Further, by processing into a pleated shape, the gas passing area increases, so it is possible to further improve the adsorptivity, and when maintaining the same adsorptivity as the planar net, further reduce the pressure loss. It becomes possible. The adsorbent of the present invention is suitable as an air conditioner for automobiles or a deodorant for air purifiers.

Hereinafter, the present invention will be described more specifically with reference to examples.

(Example 1) SBR latex was impregnated into a mesh net having a basis weight of 53 g / m ² and a mesh of 4 × 4 mm using polypropylene fiber and impregnated with SBR latex. It was adjusted. By further blowing air, the latex film formed between the fibers inside the mesh net was removed, and a binder layer was also formed on the surface of the net and the contact surface of the internal tissue with the outside air.
The net was passed through a fluidized bed of crushed activated carbon particles adjusted to a particle size of 28 to 70 mesh using palm shell as the raw material.
Activated carbon particles were attached to the surface of the reticulated net and the binder layer of the internal structure.

Further, the mesh net was passed through a pressing roll, and the activated carbon particles adhering to the binder layer were pressure-bonded to firmly bond them. The activated carbon particles attached excessively were shaken off sufficiently, and then dried at 120 ° C. to obtain a mesh net carrying the activated carbon particles.

The net-like net obtained above had an adhesion amount of activated carbon particles of 197 g / m ² , and the benzene adsorption amount measured by JIS K 1474-1975 was 59 g / m ^2. It turned out to have sex.

Further, the porous sheet obtained above is 200 mm
Two sheets of × 200 mm × 1.6 mm were stacked and placed in a box with a capacity of 1 m × 1 m × 1 m containing 250 ppm of hydrogen sulfide or 50 ppm of trimethylamine and 25 ppm of acetaldehyde, which are malodorous components, and left as it was while circulating air. Almost all of the odor was removed in 30 minutes.

(Example 2) SBR latex was impregnated into a mesh net having a basis weight of 14 g / m ² and a mesh of 4 x 4 mm using polypropylene fiber, and the weight of the latex was adjusted with a squeezing rubber roll. It was adjusted. By further blowing air, the latex film formed between the fibers inside the mesh net was removed, and a binder layer was also formed on the surface of the net and the contact surface of the internal tissue with the outside air.
The net was passed through a fluidized bed of crushed activated carbon with coconut shell as the raw material adjusted to a particle size of 70 to 100 mesh, and a mixture of activated carbon particles supporting aniline, malic acid and iron salt of the same particle size, and activated carbon particles Was applied to the surface of the reticulated net and to the binder layer of the internal texture.

Further, the mesh net supporting the activated carbon particles was passed through a pressing roll, and the activated carbon particles adhering to the binder layer were pressure-bonded to firmly bond them. After shaking off excess activated carbon particles and particles that are not strongly adhered, SBR latex is further sprayed on the surface of the mesh net and dried at 120 ° C to obtain a mesh net with activated carbon particles and good air permeability. It was

The amount of the activated carbon particles adhering to the reticulated net obtained above was 150 g / m ² , and the amount of benzene adsorbed as measured by JIS K 1474-1975 was 53 g / m ² .

(Comparative Example 1) As in Example 2, the activated carbon particles were adhered to the surface of the mesh net and the binder layer of the internal structure, and the mesh net was passed through a pressing roll to deposit the activated carbon adhered to the binder layer. The particles were crimped and firmly adhered. After shaking off the excessively adhered activated carbon particles and particles that are not firmly adhered, the mesh-like net is dried at 120 ° C without spraying SBR latex on the surface of the mesh, and the mesh-like mesh carrying the activated carbon particles. Got the net.

The amount of benzene adsorbed on the reticulated net supporting the activated carbon particles thus obtained was 59 g / m ² , which is a comparison with the amount of benzene adsorbed on the net obtained in Example 2. The decrease in the amount of benzene adsorbed by spraying SBR latex on the surface is only about 10%, and the good adsorptivity is maintained after spraying.

Example 3 The mesh net obtained in Example 1 was overlaid with an electret nonwoven fabric having a basis weight of 30 g / m ² and processed into a pleat shape having a pitch of 5 mm and a height of 20 mm.

The porous sheet obtained as described above 200 mm × 200 m
Laminates m x 20 mm, and hydrogen sulfide 500 ppm or trimethylamine 100 ppm and acetaldehyde 50 which are malodorous components
As a result of placing in a box containing ppm and having a capacity of 1 m × 1 m × 1 m and circulating air, almost all odors were removed in 30 minutes.

[0048]

In the adsorbent of the present invention, the activated carbon particles are uniformly dispersed on the base material of the mesh net in a state where the void ratio between the particles is high, and the activated carbon particles are held in an exposed state. Therefore, the adsorption rate is high and the adsorption capacity is large. Furthermore, since it is in the form of a mesh net having good air permeability, it has a very low pressure loss, and is suitable for use in an atmosphere having a low gas flowability or a large air volume. This net-shaped adsorbent can be used in the form of one pleated plate or a plurality of pleated plates.

Claims (6)

[Claims] 1. A binder layer made of a polymer adhesive containing no latex or emulsion or solvent is formed on the surface of a mesh net having good air permeability and the contact surface of the internal tissue with the outside air, and the binder layer is formed on the binder layer. An adsorbent in which activated carbon particles are adhered and held so that at least a part of the particle surface is exposed. 2. A binder layer made of a polymer adhesive containing no latex, emulsion or solvent is formed on the surface of the mesh net having good air permeability and the contact surface of the internal tissue with the outside air, and the binder layer is formed on the binder layer. Activated carbon particles are adhered to each other so that at least a part of the surface of the particles is exposed, and a coat layer made of a polymer adhesive containing no latex or emulsion or solvent is formed on the surface of the mesh net. Adsorbent. 3. The adsorbent according to claim 1, wherein the mesh net has a pleated shape. 4. A binder layer made of a polymer adhesive containing no latex or emulsion or solvent is formed on the surface of the mesh net having good air permeability and the contact surface of the internal tissue with the outside air, and the binder layer is formed on the binder layer. Activated carbon particles are adhered so that at least a part of the surface of the particles is kept exposed, and if necessary, a coat layer made of a polymer adhesive containing no latex or emulsion or solvent is further formed on the surface of the sheet. An adsorbent, an electret-treated non-woven fabric, and a conductive sheet,
An adsorbent obtained by stacking one or more sheets selected from the group consisting of a magnetic sheet or an oxidation catalyst sheet and molding them in a pleat form. 5. A sheet after forming a binder layer made of a polymer adhesive containing no latex or emulsion or a solvent on the surface of a mesh net having good air permeability and the surface of the internal tissue in contact with the outside air. By passing through a fluidized bed of activated carbon particles, the activated carbon particles are attached to the surface of the sheet and the contact surface of the internal tissue with the outside air, and at least a part of the particle surface is held exposed. Adsorbent manufacturing method. 6. The adsorbent for an air conditioner or an air purifier mounted on an automobile, as claimed in claim 1 or 2.
Adsorbents according to 3, 4, and 5.