JPH0661461B2 - Pasty composition - Google Patents

Description

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

Hitherto, as a method for producing a gas-adsorbing sheet, means for fixing powdered activated carbon or granular activated carbon to a sheet material with a fixing agent has been adopted. This method practically requires the help of large amounts of sticking agent. That is, if the amount of adhesive is small, it will easily fall off due to slight friction and vibration,
On the other hand, when a large amount of the sticking agent is used, the sticking agent coats the activated carbon, resulting in a problem that the original gas adsorption capacity of the activated carbon is significantly reduced. Further, the conventional activated carbon has a drawback that it has a small adsorption capacity for stimulating gases such as formaldehyde, acetaldehyde, hydrogen cyanide and the like.

As a result, the inventors of the present invention have made extensive studies to eliminate the disadvantages associated with the conventional technique, and as a result, have solved the problem of the conventional technique in which a specific paste composition and an absorptive sheet using the same are crushed. The present invention has been found.

That is, the present invention has a pore volume of 0.4 c or less with a pore diameter of 300 Å or less.
An activated carbon-containing paste composition, characterized in that ultrafine powdered activated carbon having a c / g or more, 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.

Such a pasty composition has a strong interaction between the cationic activated carbon and the anionic polymer electrolyte, so that the activated carbon does not fall off even if the amount of the electrolyte is small. Therefore, the disadvantage that the sticking agent coats the activated carbon and reduces the original adsorption capacity of the activated carbon as in the conventional case does not occur.

Further, due to the specific pore structure of the activated carbon according to the present invention, the adsorptivity to acetaldehyde, formaldehyde and other irritating gases, which has not been found in conventional activated carbon, is remarkably improved.

The activated carbon material used in the present invention is required to have a volume of pores having a pore diameter of 300Å or less of 0.40 cc / g or more, a basicity of pH 9 or more, and an average particle diameter of 30 μm or less. In other words, if the volume of pores with a diameter of 300 Å or less is less than 0.40 cc / g or if the average particle size exceeds 30 μm, the absorption rate for stimulating gas such as acetaldehyde will be small, and the use of PH less than 9 Has little interaction with the anionic water-soluble polymer electrolyte, and the effect of the present invention is difficult to be exhibited.

For producing the ultrafine powdery activated carbon of the present invention, there are the following methods, for example.

The coniferous wood is pulverized by a pulverizer to a particle size of 200 to 2000 μm. After that, the temperature is raised from room temperature to 500 ° C over 20 to 50 hours in a flat furnace for carbonization, and the particle size is 100 to 100
A carbide having a thickness of 1000 μm and a carbon content of 70% is obtained. The carbide is subjected to activation treatment at 1200 to 1300 ° C. for several seconds in an air transfer type flow activation furnace.

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

Such activation treatment is at a high temperature that cannot be considered by ordinary activation treatment of activated carbon, and moreover, as described below, a highly reactive wood-based raw material is activated in carbon dioxide, active gas such as steam, so that it is mostly basic. The groups are thought to be generated on the surface of activated carbon. Although the generation mechanism is not clear, it is presumed that OH groups and quinone groups are generated by activation of carbon dioxide. Alternatively, it can be obtained by reactivating the coconut shell activated carbon at a high temperature of 900 ° C or higher for a long time. As the reactivating atmosphere, carbon dioxide having a high concentration is preferable in addition to water vapor. Activated carbon is manufactured by the above-mentioned method, but its average particle size (hereinafter, simply referred to as “particle size” means the average particle size) is 3 in order to be used for the paste of the present invention.
Do not exceed 0 μm.

The basicity of the activated carbon thus obtained is the same as that of the Phillips method, that is, 0.1 NK prepared at pH 7
0.1 g of activated carbon was added to 100 ml of CI aqueous solution, shaken for 24 hours, and then measured by measuring the pH of the solution with a pH meter (eg, Industrial Chemistry Magazine 67, 2019 (1964). Basicity determined by the above method) It is presumed that the degree evaluates the amount of OH-ions ion-exchanged with CI-ions in the aqueous solution, and the average particle size is a Coulter counter method, which is one of particle size measurement methods based on the counting principle. (For example, “Powder Particle Size Measurement Method” edited by Japan Society for Powder Optics).

Furthermore, the pore diameter and pore volume of activated carbon were determined by using the nitrogen gas adsorption isotherm on the adsorption side at the boiling point of liquid nitrogen under normal pressure (-195.8 ° C), using Cranst
on-Inkley) calculation method (for example, Keicho Tominaga "Adsorption" Kyoritsu Shuppan). However, the value obtained by multiplying the nitrogen gas adsorption amount at a relative pressure corresponding to a pore diameter of 300 Å by the density ratio of gaseous nitrogen in the standard state (1.584 × 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 carboxymethyl cellulose and carboxymethyl hydroxyethyl cellulose; sodium polyacrylic acid salt.

The pasty composition of the present invention is prepared, for example, as follows. That is, the above polymer electrolyte is added to 0.1 to 20% by weight of water or hot water and stirred. Finely pulverized activated carbon is added to the obtained gel, and the mixture is stirred until it is uniformly dispersed.

The paste composition thus prepared is then attached to a non-woven fabric to prepare an adsorptive sheet.
Examples of the impregnation method include a printing method such as a roller printing method, a flat screen printing method and a rotary screen printing method, or a method of immersing in a paste composition, dehydrating and then drying. The above-mentioned non-woven fabric has a fiber length of 0.5 to 10 mm
Of the natural fibers such as cotton, wood pulp, hemp and wool, and synthetic and semi-synthetic fibers such as rayon, acetate, polyester and polyamide. Especially, in the practice of the present invention, the fiber length is 0.5 to 4.0 mm.
A wood pulp nonwoven fabric obtained by dry disintegrating the wood pulp of 1) and then making it into a non-woven fabric by a dry method is preferably used.

As described above, the paste composition and the absorptive sheet using the same are produced, and these have the following characteristics.

1. Because ultrafine powdered activated carbon with a pore volume of 0.40 cc / g or more with a pore diameter of 300 Å or less and an average particle size of 30 μm or less is used, the effect of adsorbing and removing acetaldehyde, formaldehyde, hydrogen cyanide and other irritating gases is remarkably large. Is.

2. Because it uses activated carbon with a high degree of basicity, it has a strong interaction with the anionic polyelectrolyte and the adsorption capacity does not decrease due to the adhesive.

It is speculated that this is because the strongly basic activated carbon and the anionic polymer electrolyte form a complex to form a polymer membrane having good gas permeability.

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

4. Since the non-woven fabric as the base material is made of fine fibers having a short fiber length, the adhesive effect of the paste-like substance is significantly improved.
It is speculated that this is because the polymer electrolyte coating is likely to have a structure in which the nonwoven fabric fibers and the activated carbon are integrally wrapped.

The adsorptive sheet obtained by such a method is suitable for applications such as cigarette smoke filters, absorbents for masks, and protective clothing for chemicals.

Next, the features of the present invention will be clarified with reference to examples.

Example 1 The activated carbon used was manufactured as follows.

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

(2) Carbonization treatment By heating and heating the wood waste from 200 to 500 ° C. in an open hearth overnight, the yield of 30%, the carbon content of 70%, and the particle size of
A carbide of 100 to 1000 μm was obtained.

(3) Activation treatment a) Residence time of this carbide in a fluidized activation furnace for 10 seconds, temperature 1200
~ 1300 ℃, treated with 10% steam atmosphere, particle size 30
Activated carbon of ˜200 μm was obtained. 2 the activated carbon in a ball mill
By pulverizing for 4 hours, activated carbon having a particle size of 15 μm, a pore diameter of 300 liters or less, and a pore volume of 0.60 cc / g was obtained.
(Example 1) Further, by sieving the activated carbon before pulverization treatment, the particle size is 50 μm, the basicity is pH 9.7, and the pore diameter is 300Å.
The following activated carbon having a pore volume of 0.60 cc / g was obtained. (Comparative Example 1) A residence time of 20 seconds, a temperature of 1000 ° C, and an atmosphere containing 10% of steam were applied to obtain activated carbon having a particle size of 30 to 200 µm. The activated carbon is pulverized with a ball mill to give a particle size of 15μ.
m, basicity pH 9, pore diameter less than 300Å, pore volume 0.38c
C / g of activated carbon was obtained. (Comparative Example 2) Example 2 Commercially available 8-14 mesh coconut husk activated carbon (basicity pH
7, specific surface area 600 m ² / g) was pulverized to 150 to 300 μm, and reactivated by a rotary kiln furnace at 900 ° C. for 5 hours in a combustion gas atmosphere. The activated carbon in a ball mill
Particle size is 15μm, basicity is pH 9.5 and pore volume is 0.50cc with pore diameter less than 300Å
/ G of activated carbon was obtained. (Example 2) Further, the activated carbon after 5 hours of ball mill pulverization was sieved to have a particle size of 45 µm, a basicity of pH 9.3, and
Activated carbon with a pore diameter of 300 Å or less and a pore volume of 0.50 cc / g was obtained. (Comparative Example 3) Further, the commercially available coconut husk activated carbon was subjected to a ball mill pulverization treatment to obtain a particle size of 15 µm, a basicity of pH 7, and a pore diameter of 30.
Activated carbon having a pore volume of 0.35 cc / g of 0 Å or less was obtained. (Comparative Example 4) A filter for cigarette smoke was produced by the above means using the activated carbon obtained in the above Examples and Comparative Examples. That is, 15 parts of activated carbon was added to a sodium alginate 5% by weight solution, 15 parts of water and 70 parts of water, and a dispersion treatment was performed with a colloid mill.
An attachment paste having a viscosity of about 2000 cps was obtained.

The paste was used as a dry non-woven fabric (wooden weight 4
0 g / m ² , thickness 2.2 mm) was printed with a roller printing machine to obtain a sheet having 30 mg / m ^{2 of} activated carbon impregnated.

Four sheets are used and are fed side by side so that the patterns of the four stripes are the same. The sheets are bent into an S-shape or a Z-shape and then twisted by a rotating rotor with a tapered inner diameter. By squeezing, it was rolled up into a cylinder to form a cylinder having a diameter of 8 mm. After wrapping thin paper around the outside of this cylinder, an activated carbon impregnated filter having a length of 10 mm was obtained.
The filter was joined with an acetate fiber filter having a length of 7 mm to make a cigarette smoke filter having a length of 17 mm as a trial product.

Table 1 shows the results of measurement of cyanide gas, acetaldehyde, and adsorption rate as vapor phase components of the various types of tobacco smoke filters trial-produced as described above. The adsorption rate was determined as follows.

That is, a filter manufactured by the above method was joined to a product obtained by removing the filter part from the product "Highlight" of Japan Monopoly Corporation, and a constant flow type automatic smoking device was used with the same "Highlight" as a control. Was smoked under the following conditions.

Flow rate: 17.5 ml / sec Smoke absorption time: 2 sec / time Smoke absorption frequency: 1 time / min Combustion length: 50 mm Smoke absorption number: 4 / Ultrafine glass fiber filter The acetaldehyde adsorption rate is 8 puffs passed through the ultrafine glass fiber filter. 1.95 ml of the smoke was introduced into gas chromatography, the peak height of the control was set to Hs, and the adsorption rate (F) was calculated by the following formula.

F (%) = (H−Hs) / H × 100 Further, the cyan-based gas adsorption rate was obtained by distilling the tar absorbed in the ultrafine glass fiber filter and the gas absorbing solution absorbed in 0.5N NaOH solution. The amount of CN was determined by a colorimetric method. (For example, Journal of Japanese Society of Public Health 28, 100 (1981))

Claims (1)

[Claims] 1. The volume of pores having a diameter of 300 Å or less is 0.4 cc /
A paste-like composition comprising ultrafine powdered activated carbon having a basicity of pH 9 or more and an average particle size of 30 μm or less dispersed in an aqueous solution of an anionic polymer electrolyte.