JPS60202734A - Pasty composition and adsorptive sheet obtained by using pasty composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition which is highly effective in adsorbing and removing an irritant gas such as acetaldehyde by dispersing ultrafine powdered activated carbon having specified pore volume, basicity, and mean particle diameter into an aq. soln. of an anionic high molecular electrolyte. CONSTITUTION:Ultrafine powdered activated carbon having >=300Angstrom pore diameter, >=0.4cc/g pore volume, >=9pH basicity, and <=30mu mean particle diameter is dispersed into an aq. soln. of anionic high molecular electrolyte (e.g., sodium alginate) to form a pasty composition. And the composition is deposited on an unwoven fabric sheet. The pasty composition and the adsorptive sheet are highly effective in adsorbing and removing an irritant gas such as acetaldehyde. Since the activated carbon having high basicity is used, the activated carbon interacts strongly with the anionic high molecular electrolyte. Consequently, the adsorptive power is not decreased by an fixing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paste composition attached to an adsorbent sheet and an adsorption/layer sheet attached with this paste composition.

BACKGROUND ART Conventionally, as a method of producing a gas adsorbent sheet, a method of fixing powdered activated carbon or granular activated carbon to a sheet material using a fixing agent has been employed.

This method practically requires the assistance of a large amount of fixing agent. In other words, if the amount of the adhesive is small, it will easily fall off due to slight friction or vibration, whereas if a large amount of the agent is used, the adhesive will cover the activated carbon, resulting in the inconvenience of significantly reducing the gas adsorption ability of the activated carbon. . Conventional activated carbon also has the disadvantage of having a low adsorption capacity for irritating gases such as formaldehyde, acetaldehyde, and hydrogen cyanide.

As a result of intensive studies to eliminate the disadvantages associated with the prior art, the present inventors have found that a specific paste-like composition and an adsorbent sheet made using the same have been developed to solve all the problems of the prior art. They discovered this and arrived at the present invention.

That is, the present invention has a pore diameter of 300x or less and a pore volume of 0.
4cc/f or more, basicity PH9 or more, average particle size 30
A paste-like composition in which ultrafine powdered activated carbon of μm or less is dispersed in an aqueous solution of an anionic polymer electrolyte,
In addition, paste-like compositions such as this one, which is based on an adsorbent sheet made using Kowa, have a strong interaction between cationic activated carbon and anionic polymer electrolyte, and the amount of electrolyte increases. At least the activated carbon does not fall off. Therefore, there is no problem that the adhesion agent coats the activated carbon and reduces the adsorption capacity of the activated carbon as in the conventional method.

Furthermore, due to the unique pore structure of the activated carbon according to the present invention, the adsorption ability for irritating gases such as acetaldehyde and formaldehyde, which was not found in conventional activated carbon, was significantly improved.

The activated carbon material used in the present invention needs to have a pore volume of 0.40 cc/9 or more with a pore diameter of 300X or less, a basicity of PH9 or more, and an average particle size of 30 μm or less. In other words, if the volume of pores with a pore diameter of 300X or less is less than 0.40 cc/9 or the average particle size exceeds 30 μm, the absorption rate of irritating gases such as acetaldehyde will be reduced, and if the pore diameter is less than 9. However, the effect of the present invention is difficult to exhibit when using a monoanionic water-soluble polymer electrolyte because the interaction with the monoanionic water-soluble polymer electrolyte is small.

For example, the following method can be used to produce the ultrafine activated carbon powder of the present invention.

Coniferous wood is ground to a particle size of 200 to 2000 μm using a grinder. Thereafter, carbonization treatment is carried out by raising the temperature from room temperature to 500° C. over 20 to 50 hours in an open hearth to obtain a carbide having a particle size of 100 to 1000 capes and a carbon content of 7 d%. The carbide was heated to 120 ml in an air transfer type fluidized activation furnace.
Activation treatment is performed at 0 to 1300°C for several seconds.

The pulverization treatment is performed by pulverizing activated carbon coarsely pulverized to 50 to 100 μm using a ball mill or the like for a long time.

This activation treatment involves a high temperature that is unimaginable for ordinary activated carbon activation treatment, and as will be described later, since the highly reactive wood-based raw materials are activated in active gases such as carbon dioxide gas and water vapor, many of them are basic. It is thought that groups are generated on the surface of activated carbon. Although the formation mechanism is not clear, it is presumed that OH groups and quinone groups are generated by activation of carbon dioxide gas. Alternatively, it can also be obtained by reactivating coconut shell activated carbon at a high temperature of 900° C. or higher for a long period of time. In addition to water vapor, highly concentrated carbon dioxide gas is preferable as the reactivation atmosphere. Activated carbon is produced by the above-mentioned method, but in order to be used as the base to the base of the present invention, its average particle size (hereinafter simply referred to as 1 particle size means average particle size) is required. Must not exceed 30 μm.

The basicity of the activated carbon thus obtained was determined by a method similar to the Phillips method, that is, 0, 1N, which was adjusted to pH 7.
Activated carbon 0.11 was added to 100 ml of KCI aqueous solution,
After shaking for 24 hours, measure the pH of the solution with a pH meter (for example, Industrial Chemistry Magazine 67.2019
(1964). It is presumed that the basicity determined by the above method evaluates the amount of OH- ions ion-exchanged by CI- ions in the aqueous solution. In addition, the average particle size is determined by Coulter, which is a particle size measurement method based on the counting principle.
It was measured by a counter method (for example, "Powder Particle Size Measurement Method" in the entire volume of Powder Optics Research).

Further, the pore diameter and pore volume of the activated carbon were determined by adsorption at the boiling point of liquid nitrogen (-195.8°C) under normal pressure (Kei Tominaga, "Adsorption", Kyoritsu Shuppan).

However, the ratio (,1,
The value multiplied by s 84×10−3) was regarded as the total pore volume.

Examples of the water-soluble anionic polymer electrolyte used in the present invention include sodium alginate; soda salts such as carboxymethylcellulose and carboxymethylhuman tetraxyethylcellulose; and sodium polyacrylate salts.

The paste composition of the present invention is prepared, for example, as follows. That is, 0.1 to 20% by weight of the polymer electrolyte is poured into water or hot water and stirred.

Finely ground activated carbon is added to the resulting gel and stirred until uniformly dispersed.

The paste-like composition prepared in this way is then attached to a nonwoven fabric to form an adsorbent sheet.

Examples of the impregnating method include printing methods such as roller printing, flat screen printing, and rotary screen printing, or immersion in a paste composition, dehydration, and drying.

The above-mentioned non-woven fabrics include natural fibers such as cotton, wood pulp, linen, wool, rayon, acetate, etc. with a fiber length of 0.5 to 10 prints.
Refers to dry and wet nonwoven fabrics made of synthetic and semi-synthetic fibers such as polyester and polyamide.

In particular, in the practice of the present invention, the fiber length is 0.5 to 4°0.
A wood pulp nonwoven fabric obtained by dry disintegrating and then turning wood pulp into a nonwoven fabric is preferably used.

As described above, the paste composition according to the present invention and the adsorbent sheet using the same are produced.
These have the following characteristics.

1. Pore volume with pore diameter of 300X or less is 0.40cc
Since ultrafine activated carbon with an average particle diameter of 1/1 or more and 30 μm or less is used, the adsorption/removal effect on irritating gases such as acetaldehyde, formaldehyde, and water cyanide is significantly large.

2. Since active P with high basicity is used, it has a strong interaction with the anionic polymer electrolyte and does not cause a decrease in adsorption capacity due to the adhesion agent.

This is presumed to be because the strongly basic activated carbon and the anionic polymer electrolyte form a complex, forming a polymer membrane with good gas permeability.

3. The interaction between the highly basic activated carbon and the anionic polymer electrolyte also has a positive effect on the rheological properties of the paste, improving transferability to the base sheet.

4. Since the nonwoven fabric that is the base material is made of fine fibers with short fiber length, the adhesive effect of the paste material is greatly improved. This is presumed to be because the polymer electrolyte film tends to form a structure in which the nonwoven fabric fibers and activated carbon are integrally wrapped.

The adsorbent sheet obtained by this method is suitable for uses such as cigarette smoke filters, absorbents for masks, protective clothing for chemicals, and the like.

Next, examples will be given to clarify the characteristics of the present invention.

Example 1 The activated carbon used was manufactured as follows.

(1) Wood raw materials Coniferous wood waste with a particle size of 200 to 2000 μm.

(2) Carbonization treatment The wood chips are heated to 200 to 500 degrees Celsius for one day and night in an open hearth.
By heating, with a yield of 30% and a carbon content of 70%,
A carbide having a particle size of 100 to 1000 μm was obtained.

(3) Activation treatment a) The carbide is placed in a fluidized activation furnace for a residence time of 10 seconds and a temperature of 12
00~1300℃, treated in an atmosphere containing 10% water vapor 1
, activated carbon with a particle size of 30 to 200 μm was obtained.

By pulverizing the activated carbon in a ball mill for 24 hours, the particle size is 15 μm, the pore diameter is 300X or less, and the pore volume is 0.
-60 cc/f of activated carbon was obtained. (Example 1) In addition, by sieving the activated carbon before pulverization, the particle size of 5
0 μm, basicity pH 9.7, pore volume 0.60 co/? with pore diameter 300X or less? of activated carbon was obtained. (Comparative example 1
) Activated carbon having a particle size of 30 to 200 μm was obtained by treatment with a residence time of 20 seconds, a temperature of 10θ0° C., and an atmosphere containing 10% water vapor.

The activated carbon was pulverized with a ball mill to obtain activated carbon having a particle size of 15 μm, basicity of pH 9, pore diameter of 300× or less, and pore volume of 0.38 cc/f.

(Comparative Example 2) Example 2 Commercially available coconut shell activated carbon (basicity p
H7, specific surface area 6oon? /r) from 150 to 300 μm
The powder was crushed into powder and subjected to reactivation treatment in a rotary kiln at 900° C. under a combustion gas atmosphere for 5 hours. The activated carbon was pulverized in a ball mill for 100 hours to obtain activated carbon having a particle size of 15 μm, a basicity of pH 9.5, a pore diameter of 300× or less, and a pore volume of 0.50 cc/S′. (Example 2) In addition, by sieving the activated carbon after 5 hours of ball mill pulverization, it was found that the particle size was 4571 m, the basicity was 9,
3. Pore volume 0.50cc/f with pore diameter 300X or less
of activated carbon was obtained. (Comparative Example 3) The commercially available coconut shell activated carbon was further subjected to a ball mill pulverization treatment to obtain activated carbon having a particle size of 15 μm, basicity of pH 7, pore diameter of 300× or less, and pore volume of 0.35 cc/f′. (Comparative Example 4) Using the activated carbon obtained in the above Examples and Comparative Examples, a cigarette smoke filter was produced in the manner described above.

That is, 15 parts of activated carbon was added to a 5% by weight solution of sodium alginate, 15 parts, and 70 parts of water, and a dispersion treatment was performed using a colloid mill to obtain an impregnating paste having a viscosity of about 2000 cps.

The paste was applied to a dry non-woven fabric made of wood pulp (fabric weight 4
01P/y71'', thickness 2.2 mm) was printed using a roller printing machine to obtain a sheet impregnated with activated carbon at 30 mm/R.

Four of these sheets are used and fed side by side so that the striped patterns of the four sheets match, and after being folded into an S-shape or two-shape, they are twisted together by a rotating rotor with a tapered inner diameter. By squeezing and rolling it up into a cylindrical shape, a cylinder with a diameter of 8 pieces was made. After wrapping thin paper around the outside of this cylinder, an activated carbon-impregnated filter with a length of 10 m was obtained.

This filter was joined with an acetate fiber filter having a length of 7 m to fabricate a cigarette smoke filter having a length of 17+mn.

Regarding the various cigarette smoke filters trial-manufactured as described above, the vapor phase components include cyanide gas, acetaldehyde,
Table 1 shows the results of measuring the adsorption rates. The adsorption rate was determined as follows.

In other words, a sample cigarette was prepared by attaching a filter manufactured by the above method to a part of the Japan Monopoly Corporation product "Highlight" from which a portion of the filter had been removed, and the same "Highlight" was used as a control for constant-flow automatic smoking. 0 flow rate: 17.5 me/see smoking time:
2 see 7 times Smoke frequency: 1 time / Long burn length: 50 Number of smokes: 4 / Ultra-fine glass fiber filter The adsorption rate of acetaldehyde is 1.95 mJ of the 8 puffs of smoke that passed through the ultra-fine glass fiber filter. Introduce it to gas chromatography, set the peak height of the control to Hs,
The adsorption rate (F) was calculated using the following formula.

F (%) = (H-us) / HX 100 Also,
The cyanide gas adsorption rate was determined by calculating the amount of CN by a colorimetric method after distilling the tar and 0.5 N NaOH solution absorbed by the ultrafine glass fiber filter. (For example, Japanese Society of Public Health Journal 28.100 (198
1)) (Left below)

Claims (1)

[Claims] (1) The pore volume with a pore diameter of 300X or less is 0. ．． 4cc
A paste-like composition comprising ultrafine powdered activated carbon having a basicity of PH9 or more and an average particle size of 30 μm or less, dispersed in an aqueous solution of an anionic polymer electrolyte. f2) The pore diameter is less than or equal to m pore volume 0
, 4 cc/7 or more, a paste composition in which ultrafine powder activated carbon with a basicity of pH 9 or more and an average particle size of 30 μm or less is dispersed in an aqueous solution of an anionic polymer electrolyte is attached to a nonwoven fabric sheet. An absorbent sheet.