JPH04171045A - Heat-resistant and fire retardant adsorbing material - Google Patents

Abstract

PURPOSE:To obtain a fire retardant adsorbent having high adsorbing capacity by applying embossing processing to activated carbon fiber sheets formed from a specific composition by a papermaking process before laminating the same by a heat-resistant adhesive. CONSTITUTION:An activated carbon fiber sheet containing 40-87wt.% activated carbon fibers, 10wt.% aromatic polyamide staple fibers and 3-50wt.% pipe-like aromatic polyamide fibers as essential components is formed by a wet papermaking process and subsequently subjected to embossing processing. Further, a plurality of the embossed sheets are laminated so that the embossed apex parts 3, non-processed parts or embossed parts and the sheets 1 are bonded by a heat-resistant adhesive. The adsorbent thus obtained is heat-resistant and fire retardant and effectively performs adsorption.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-resistant and flame-retardant adsorbent for adsorbing and separating foul odors, organic substances, or dissolved substances in fluids, and a method for producing the same.

[Prior Art] In recent years, environmental issues such as foul odors and toxic gases such as organic solvents have been increasingly discussed.

As a means of preventing these toxic gases, adsorbent materials, especially activated carbon, have traditionally been used. In recent years, instead of powdered or particulate activated carbon, fibrous activated carbon, that is, activated carbon fiber, has appeared and is attracting attention. Activated carbon fibers are rapidly being developed because of their extremely high gas adsorption speed.

When forming activated carbon fibers into a sheet, a binder is required because activated carbon fibers do not have self-adhesive properties. As binders for activated carbon fibers, various solution-type and emulsion-type liquid binders and fibrous binders are generally used.

The use of a liquid binder is not preferred because it blocks the pores of the activated carbon fibers and reduces the adsorption capacity.

On the other hand, fibrous binders include organic resins in the form of fibers or pulp, but financial type binders are not preferred because the melted resin covers the surface of the activated carbon fibers. On the other hand, there is one that has two components, a core component and a sheath component, and uses a low melting point resin for the sheath component to effectively bond the contact points between the activated carbon fiber and the binder fiber.

However, none of these fibers has heat resistance, and under temperature conditions exceeding the fusion temperature, they will melt again or
Alternatively, it may collapse or the components may burn when exposed to flame, making it impossible to maintain sheet strength. Furthermore, if a large amount of these components is contained, the sheet itself becomes flammable, which is extremely dangerous.

Activated carbon's gas adsorption properties are more likely to be adsorbed at low temperatures, and more likely to be released at high temperatures, so activated carbon fiber sheets and molded products are rarely used at high temperatures.
-The adsorbed gas is released under high temperature to regenerate the adsorption capacity and recover the adsorbed material. However, as mentioned above, due to the shortcomings in heat resistance, conventional activated carbon fiber sheets or molded products made from them are difficult to recycle, and their uses are limited.

In order to perform adsorption effectively, it is necessary to bring the substance to be adsorbed into sufficient contact with the activated carbon fiber. For this purpose, it is best to pass the fluid perpendicularly to the activated carbon fiber sheet, but it is inevitable that the pressure loss will be high. As a method of contacting
It is disclosed in Japanese Patent Publication No. 59-51432.

That is, an activated carbon fiber sheet is processed into a corrugated shape and laminated with a flat sheet to produce a honeycomb or corrugated structure, which is then wound into a cylindrical shape. By flowing the fluid parallel to the sheet surface of the molded product, filtration resistance is lowered and contact with the adsorbed material is maintained. Also, JP-A-61-121
In Publication No. 1934 and Japanese Unexamined Patent Publication No. 63-78739,
An example is given of an adsorbent that can be recycled by processing a sheet using flame-retardant and heat-resistant synthetic pulp to create a honeycomb structure.

In order to achieve more efficient adsorption than this honeycomb structure, an attempt was made to obtain sufficient contact time by embossing the sheets, stacking them, and flowing fluid parallel to the sheets to perform adsorption. is being done. but,
In these attempts, it was not possible to obtain an embossed laminate having heat resistance and flame retardancy due to embossability and adhesion during lamination.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned conventional problems, and aims to provide an adsorbent that can effectively adsorb and has heat-resistant and flame-retardant properties. .

[Means for Solving the Problems] The present inventors conducted extensive research in order to solve the above problems. As a result, the activated carbon fibers obtained by paper-making using a wet paper-making method include 40 to 87% activated carbon fiber, 10% or more aromatic polyamide short fibers, and 3 to 50% pulp-like aromatic polyamide as essential components. If the sheet is embossed, it can be processed.For the embossed pattern, use multiple activated carbon fiber sheets for the embossed pattern, and use a heat-resistant adhesive to attach the top and unprocessed part or the processed part and the activated carbon fiber sheet for the embossed pattern. It was discovered that a heat-resistant, flame-retardant deodorizing material could be obtained by laminating layers using 4r), and the present invention was completed.

That is, the present invention is a heat-resistant, flame-retardant adsorbent made by embossed and laminated sheets containing activated carbon fibers and short fiber-like and pulp-like aromatic polyamides.

The present invention will be explained in detail below.

First, the components used in the present invention will be explained.

The activated carbon fiber used in the present invention differs from ordinary carbon fiber in that it has micropores on the fiber surface, and has a specific surface area of
Adsorption capacity etc. can be selected depending on the purpose, but specific surface area, 500
m/g or more, and benzene adsorption capacity of 200 mg/g or more is preferable. Further, the activated carbon fibers may be those that can be dispersed in water, and if it is difficult to disperse, a sticky agent or a dispersant may be added as appropriate and stirred. Average fiber length is 0.05QIff1~15
mm, preferably 0.5 mm to 10 mm. 0.
If it is shorter than 0.05 mm, the sheet becomes dense, the air permeability of the sheet decreases, and the activated carbon fibers fall off, and if it is longer than 15 mm, dispersion in water becomes poor and a sheet with a uniform and good texture cannot be obtained. The average fiber diameter is 5 μm to 30 μm, preferably 10 μm or more. If it is thinner than 5 μm, the sheet will become dense and the air permeability of the sheet will be reduced, and if it is thicker than 30 μm, it will be difficult to pick up from the wire and a uniform and well-formed sheet will not be obtained.

The aromatic polyamide short fibers used in the present invention have an aromatic group in the main chain, and mainly contain one or more components selected from aromatic dicarboxylic acids and their acid chlorides, and aromatic diamines. Aromatic dicarboxylic acids and aromatic diamines may take para-form or meta-form, but are not particularly limited in the present invention. The length of the fiber used is 3mm to 15m.
m is preferably 5 to 10 mm. If it is shorter than 3mm, cracks will occur when the sheet is embossed, and the length of 15m
If the length is longer than m, dispersion in water is poor and a uniform sheet cannot be obtained. The average fiber diameter is 30 μm or less. 3
If it is larger than 0 μm, cracks will still occur in the embossing, which is not preferable.

The pulp-like aromatic polyamide used in the present invention is a pulp-like material made of the above-mentioned aromatic polyamide polymer,
Fiber fibrils and fibrids are preferred. Fibrillated material refers to fibrils obtained by grinding fibers. Fibrids are obtained by the method disclosed in Japanese Patent Publication No. 40-9044, and refer to fiber fibrils or particles obtained by dropping a polymer from a polymer solution onto a coagulant under high-speed shearing to coagulate and precipitate it. The Canadian standard freeness of the pulp aromatic polyamide is preferably 100 ml or less.

When it is higher than 100 m1, the binder effect decreases.

Next, the component ratio of the sheet of the present invention will be explained.

Activated carbon fiber accounts for 40-87% of the weight of the sheet.

If it is less than 40%, sufficient adsorption performance cannot be exhibited. 8
If it exceeds 7%, the sheet strength will be weak (as will be described later, but this is not preferable because the embossment will crack when embossed).

It is used as a pulp aromatic polyamide binder and is 3 to 50% based on the weight of the sheet. If it is less than 3%, the sheet strength will be weak, which is not preferable. If it exceeds 50%, the amount of activated carbon fiber decreases, which is not preferable.

The amount of aromatic polyamide short fibers is 10% or more based on the weight of the sheet. If it is less than 10%, cracks will occur at the apex of the embossing during embossing. If the apex of the emboss is cracked, it will be difficult to apply the adhesive, which is undesirable.

The basis weight of the sheet is 30-300g/cr? So, 30g/r
When it is smaller than d, the embossed apex is entered and 30
If it exceeds 0 g/m, it will be difficult to shape the embossing.

Next, a method for manufacturing an activated carbon fiber sheet will be described. The above components are sequentially added to water to prepare an aqueous slurry. The slurry concentration is preferably 0.5% or less. 0.
If it exceeds 5%, uniform dispersion is difficult. The thus prepared slurry is made into paper to produce a sheet. As the paper machine, a paper machine having a circular screen, a Fourdrinier, a short screen, or an inclined wire, or a paper machine equipped with a plurality of these can be used. The paper-made wet paper is pressed and dried to obtain an activated carbon fiber sheet. Drying is carried out at a temperature below the glass transition point of the aromatic polyamide.

preferable.

If necessary, spray or apply water repellent to this sheet.
Water repellency may be achieved by impregnating and drying. Alternatively, paper may be made by mixing a sizing agent with the slurry.

Further, the sheet of the present invention can be mixed with other fibers and made into paper if necessary, but in this case, it is essential that the fibers are flame retardant. It is also possible to mix an inorganic filler and make paper. Furthermore, it is also possible to contain natural/chemical deodorants and natural/synthetic fragrances. However, the content of these substances must not be within a range that impairs the performance of the sheet of the present invention.

Next, embossing will be explained. Embossing can be done by passing the sheet between upper and lower uneven embossing rolls. At this time, the radius of the roll is preferably 50 to 5000 mm. If the 50 mm droplet is not used, the emboss will not be cleaned up enough. The embossing speed is 5 to 50 m/min, and if the speed exceeds 50 m, the embossment will not be cleaned up properly. Nip pressure is 20 in linear pressure
~100 kg f/cm. 20k
g f / cm If there are no drops, cleaning is insufficient, 100
If it exceeds kg f/cm, the sheet will be damaged.
Activated carbon fibers scatter, which is undesirable. There are no particular restrictions on the temperature of the rolls, but it is appropriate to keep the temperature within the range of 50 to 300°C.

The spacing between the embossing is preferably 1 to 20 mm (see Figure 3 (a)
) of 4). If the thickness is less than 1 mm, there will be few gaps in the adsorbent when stacked, resulting in increased ventilation resistance. If it exceeds 20 mm, there will be less embossment within the sheet and the adhesive force between the laminated layers will be weak, which is not preferable.

There is no particular restriction on the shape of the embossing, but it may be any shape that allows easy application of adhesive to the apex. - An example is a dome-shaped one (Fig. 11ffl, Fig. 2). In this case, the diameter of the circle (5 in FIG. 3(a)) is preferably 3 to 15 mm. The height of the embossing (6 in FIG. 3(b)) is preferably 1/3 to 1/2 of the diameter. Emboss diameter is 3mm
If the height is increased when the adsorbent is not dripped, the embossed apex will crack, and if it is lowered, when stacked, there will be fewer gaps in the adsorbent and the ventilation resistance will increase. If it exceeds 15 mm, the adhesive strength between the laminated layers will be weak, which is not preferable.

Even if an attempt is made to produce such an embossed size, if the activated carbon fiber sheet is made with a mixture of only pulp-like fibers other than the one according to the present invention, cracks may occur at the embossed apex or the sheet may be damaged, making it impossible to produce an embossed sheet. There wasn't. Further, even if the sheet can be embossed, if the sheet is combustible, it is not within the scope of the present invention.

Applying a heat-resistant adhesive to the embossed apex (3 in Figures 1 and 2) of the embossed sheet produced by the method of the present invention,
The heat-resistant and flame-retardant adsorbent of the present invention is formed by laminating the sheets so that the embossed portions do not overlap (FIG. 1), or by laminating an embossed sheet and a planar sheet (FIG. 2).

It is necessary to use a heat-resistant adhesive, and examples thereof include polyimide resin, phenol resin, silicone resin, and epoxy resin. These resins generally need to be cured by heating at high temperatures, and by exposing the embossed laminated adsorbent material of the present invention to high temperatures, the bond between the pulp-like aromatic polyamide and the activated carbon fibers becomes stronger, and A secondary effect is that impurities adsorbed on activated carbon fibers during production can be removed.

The adsorbent of the present invention is not only recyclable, but also
It has high flame retardancy, and is particularly effective when incorporated into equipment that consumes electricity, oil, gas, etc. and generates bad odors.

[Function] The processed activated carbon fiber sheet of the present invention has a high adsorption effect, can be regenerated by heating, and functions effectively as a heat-resistant and flame-retardant adsorbent.

[Example] The present invention will be specifically explained with reference to Examples below, but the present invention is not limited to these Examples.

In the examples, all parts and percentages are by weight.

Examples 1 to 9, Comparative Examples 1 to 3 Activated carbon fibers (Adole A-15, fiber length 6 mm, specific surface area 1500 rd/g, manufactured by 7 Dollar Company) were added to water and adjusted to a concentration of 0.3%. . sv type reciprocating stirrer (
Aromatic polyamide short fibers (Avière fiber, fiber length 5 mm, manufactured by Unitika) were mixed while being dispersed with a Agitator (manufactured by Takasaki Seisakusho). After this, Canadian standard freeness 80m
Pulp-like aromatic polyamide adjusted to
Fibrid (manufactured by Unitika) was mixed with stirring in an agitator, water was added, and 0. The slurry was adjusted to a 1% concentration. The relationship between formulation and physical properties is shown in Table 1 (Example) and Table 2
(Comparative example). In addition, the machining speed is 15 m/min, the nip pressure is 35 kgf/cm, and the shape of the +1-emboss is a circle with a diameter of 8 m.
Embossing was performed with a height of 4 mm and a spacing of 3 mm. The results are also shown in Table 1.2.

In addition, a flame retardancy test was conducted in accordance with UL94V.

(Margin below) Table 1 (Example) *ACF is activated carbon fiber, FD is pulp-like aromatic polyamide, and F is Avière fiber.

As shown in the examples, all the sheets that met the conditions of the present invention showed good embossing properties. However, as in the comparative example, when either the pulp-like aromatic polyamide or the aromatic polyamide fiber did not satisfy the conditions, the sheet was broken and the embossing property was unsuitable. In addition, if the activated carbon fiber content is less than 40%, even if the embossing property is good, the adsorption performance is poor when used in a laminated manner, which is not preferable.

In addition, flame retardancy tests were conducted on the sheets of the examples according to UL 94V (vertical direction), and the class was V-0.
was confirmed to have the highest flame retardant properties.

(Comparative Example 4) An active material with a basis weight of 152 g/d containing 50% ACF, 40% boethylene pulp (swp, manufactured by Mitsui Petrochemicals), and 10% polyester binder fiber (Merchii 4080.2dX5mm, manufactured by Unitika). Carbon fiber sheets were made and tested in the same manner.

Embossing was easy, but in a flame retardant test, the sheet burned and spread to the absorbent cotton underneath.

[Effects of the Invention] The heat-resistant and flame-retardant adsorbent of the present invention has the highest flame retardancy and high adsorption performance. Contains a large amount of activated carbon fiber, does not cover the specific surface area, and the laminate effectively absorbs odors.

[Brief explanation of drawings]

FIG. 1: A perspective view showing the shape of the heat-resistant and flame-retardant adsorbent of the present invention. FIG. 2: A perspective view showing the shape of another heat-resistant and flame-retardant adsorbent of the present invention. Figure 3(a): The molding is a view of the activated carbon fiber sheet viewed from above. Figure 3(b): The molding is a cross-sectional view of the activated carbon fiber sheet. 1: Embossed activated carbon fiber sheet 2: Activated carbon fiber sheet 3: Emboss apex 4: Emboss spacing 5: Emboss diameter 6: Emboss height Arrows indicate the flow of two fluids.

Claims (1)

[Claims] 40-87% by weight activated carbon fiber, 10% aromatic polyamide staple fiber, 3-50% pulp aromatic polyamide
An activated carbon fiber sheet obtained by paper-making using a wet paper-making method is embossed using the following as an essential component, and a plurality of embossed activated carbon fiber sheets are combined, and the embossed top part and the unprocessed part or the embossed processed part and the activated carbon fiber sheet are heat-resistant. Heat-resistant and flame-retardant adsorbent laminated using adhesive.