JPH0947623A - Adsorptive sheet and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorptive sheet with excellent deodorizing effect to aldehyde gas and excellent stable adsorption and removing properties for a long time exhibiting no decrease in performance with time. SOLUTION: A sheet contg. an active carbon material is provided with an aliph. amine layer and a weak acid layer on the surface layer part of at least one face of the sheet. The active carbon material is pref. finely particulate active carbon. The aliph. amine layer is pref. a polyalkyleneamine or ethanolamine.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an office, an automobile,
TECHNICAL FIELD The present invention relates to an adsorbent sheet used for removing odors from indoor air for home use and a method for producing the same, and particularly an adsorbent sheet excellent in long-term stable adsorption / removal of aldehyde gas such as acetaldehyde in tobacco odor, and a method for producing the same. Regarding

[0002]

2. Description of the Related Art For the purpose of removing aldehyde gases such as acetaldehyde in tobacco odor contained in air,
Various adsorbent sheets in which an aliphatic amine or an aromatic amine is impregnated on a sheet containing activated carbon have been proposed.

As one of such sheets, Japanese Patent Publication No. 62-51651, which is a method for removing an aldehyde gas in which polyalkyleneimine is impregnated on activated carbon, an aldehyde gas in which an ethanol-based aliphatic amine is impregnated on activated carbon is disclosed. There is a Japanese Patent Publication No. 63-24413. However, these methods have a problem that the adsorbability of aldehyde-based gas decreases with time.

On the other hand, ethanol-based aliphatic amines have pK
There is Japanese Patent Publication No. 63-24414, which is a method for removing an aldehyde-based gas obtained by impregnating a weak acid buffer having a 3.5 to 5.5 with activated carbon contained in a sheet. Although this method has a smaller performance deterioration rate than the above-mentioned method, the problem that the adsorbing ability of the aldehyde gas decreases with time still remains.

The reason why the performance deterioration rate with time is small is as follows.
It is presumed that the primary amine and the secondary amine were complexed with the weak acid due to the buffering with the weak acid and became stable. However, this buffering method was not sufficient to eliminate the time-dependent decrease in the adsorption capacity of the aldehyde gas.

[0006]

DISCLOSURE OF THE INVENTION The present invention is intended to remove a trace amount of malodorous components present in daily living space, and particularly has an excellent deodorizing effect on aldehyde gas and has a performance deterioration over time. The present invention is intended to propose an adsorptive sheet excellent in long-term stable adsorption / removability and a method for producing the same.

[0007]

According to the present invention, which has been able to solve the above-mentioned problems as a result of various investigations, a sheet containing an activated carbon material is impregnated with an aliphatic amine which is an adsorbent for an aldehyde gas. By drying and fixing the amine at this point, and further by impregnating and drying a weak acid having a pKa of 3.5 to 5.5, a complex of the amine fixed on the activated carbon and the weak acid is formed. It was found that the weak acid complex amine adhered to the activated carbon enables long-term stable adsorption / removal of aldehyde gas.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The sheet used in the present invention contains an activated carbon material, and preferably contains particulate activated carbon, more preferably supporting fibers, and water-swellable fibers or heat-meltable fibers. .

Preferably, the sheet contains 10 to 80 parts by weight of the particulate activated carbon and 5 to 50 parts by weight of the supporting fiber,
It contains 1 to 30 parts by weight of water-swellable fiber or heat-meltable fiber.

The average particle diameter of the above-mentioned fine particle activated carbon is 6 according to the JIS standard sieve (JIS Z8801).
The thickness is preferably 0 to 150 μm, more preferably 100 to 150 μm. In addition, JIS K1474
Adsorption amount of toluene is 20 wt% when measured according to
The above is preferable, and one having a large volume of pores in the transitional pore region of 30 to 300 Å is preferable.

The supporting fiber has an outer surface area of 1 m ² / g.
The following are preferable. As the supporting fiber, polyester, polyacrylonitrile, polyamide, other than synthetic fibers such as polyolefin, linter, cotton, hemp, wood pulp, rayon, glass fiber, ceramic fiber, carbon fiber, activated carbon fiber and the like can be used, preferably Wood pulp and rayon. These fibers have a fiber length of 3 to 2
It is preferably 0 mm short fiber.

The above water-swellable fiber or heat-fusible fiber is
The water-swellable fibers include polyvinyl alcohol fibers and the like, and the heat-meltable fibers include polyethylene fibers and polypropylene-polyethylene composite fibers. These fibers preferably have a fiber length of 20 mm or less.

The thickness of the sheet is preferably about 0.3 to 1.2 mm in consideration of air permeability and workability. The basis weight is preferably 60 g / m ² or more from the viewpoint of adsorptivity.

The adsorbent for the aldehyde-based gas to be attached and dried on this sheet is not particularly limited, and may be an aliphatic amine having low volatility and high stability to some extent.

For example, polyethyleneimine having an average molecular weight of 300 to 100,000 as polyalkyleneimine; monoethanolamine, N-aminoethylethanolamine, N-methylethanolamine, ethyl as aliphatic primary amine or aliphatic secondary amine Ethanol amines such as monoethanolamine, dimethylethanolamine and diethylethanolamine; monoisopropanolamine; triethylenetetramine, tetraethylenepentamine, hexamethylenediamine, benzylamine, xylylenediamine and the like. Mixtures of these aliphatic amines are also used.

A weak acid having a pKa of 3.5 to 5.5 is used as the weak acid for complexing the amine fixed to the activated carbon, and the weak acid is not particularly limited.

Examples thereof include saturated monocarboxylic acids such as acetic acid, propionic acid and butyric acid, malic acid, lactic acid, succinic acid and glutamic acid.

A weak acid having a pKa of less than 3.5 has a drawback that the ability to form a complex with an amine compound is insufficient, and a weak acid having a pKa of more than 5.5 has an excessively large ability to form a complex, resulting in a complex-forming reaction. Not only stays in the surface layer, but also progresses to the inside, reducing the purpose and effect.

The aldehyde-based gas adsorbent is first attached and dried on the sheet containing activated carbon. Examples of this attachment method include, but are not limited to, ordinary coating methods such as a gravure direct method, a kiss coat method, a lip coater method, and a comma direct method. The drying method includes, but is not limited to, a hot air drying method and a method using a rotary drying drum. The amine is fixed to the activated carbon by this impregnation drying.

After the amine is fixed to the activated carbon,
The weak acid for forming a complex can be impregnated and dried in the same manner as the adsorbent for the aldehyde gas.

In the case of applying by a coating method, the paste can be applied to a sheet without causing unevenness of attachment by applying a paste-like attachment liquid having an adhesive agent. As a thickener for imparting viscosity, polyacrylic acid sodium, synthetic water-soluble polymer system such as polyethylene oxide, carboxymethyl cellulose, semi-synthetic water-soluble polymer system such as hydroxyethyl cellulose, sodium alginate, guar gum, xanthan gum, Natural water-soluble polymeric thickeners such as gum arabic are preferred. However, it is not limited to these.

The viscosity range of the paste using such a thickener is preferably 100 cps to 5000 cps, more preferably 500 cps to 2500 cps.

The above-mentioned impregnating solution is used to impregnate and dry.
At this time, it is preferable that the attached amount is 1 to 20% by weight based on the weight of the sheet material.

In this way, the aliphatic amine is impregnated and dried on the sheet containing the particulate activated carbon, and the pKa is further added.
An adsorptive sheet is obtained in which a weak acid of 3.5 to 5.5 is overcoated and dried. The absorptive sheet of the present invention can be used as a filter incorporated in, for example, offices, automobiles, home air conditioners, and the like.

The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any modification or implementation is possible without departing from the spirit of the preceding and the following. Included in the range.

[0026]

[Example] TAPPI paper machine average particle size: 105μ
m, toluene adsorption amount: 50% by weight of fine particulate activated carbon 6
19% rayon with 8% by weight and external surface area: 0.8 m ² / g
% Of polyvinyl alcohol fiber as a binder, dried with a Yankee dryer at 120 to 130 ° C., basis weight 100 g / m ² , thickness 0.5 mm
Was prepared.

The sheet (a) produced as described above is attached by a gravure direct method using various paste-like attachment liquids and dried by a rotary drying drum to produce various absorptive sheets. The characteristics were investigated.

In order to impart viscosity to the impregnating solution, sodium alginate was used as the thickener for the aldehyde-based adsorbent paste, and guar gum was used as the thickener for the weak acid paste.

Example 1 A sheet (a) was provided with polyethyleneimine (molecular weight: 3 as an adsorbent for aldehyde gas).
5% by weight of a paste containing 00) having a viscosity of 500 cps was impregnated and dried. Then, 5% by weight of a paste containing malic acid as a weak acid and having a viscosity of 500 cps was attached to the same surface and dried to obtain an adsorptive sheet.

Example 2 A sheet (a) was impregnated with 5% by weight of a paste containing aminoethylethanolamine as an adsorbent for aldehyde gas and having a viscosity of 500 cps, and dried. Then, 5% by weight of a paste containing malic acid as a weak acid and having a viscosity of 500 cps was attached to the same surface and dried to obtain an adsorptive sheet.

Example 3 On both sides of the sheet (a), 5% by weight of a paste having a viscosity of 500 cps containing polyethyleneimine (molecular weight: 300) as an adsorbent for aldehyde gas was impregnated and dried. Next, 5% by weight of polyethyleneimine (molecular weight: 300) was attached to one surface of the adsorptive sheet and dried.

Then, a paste having a viscosity of 500 cps containing malic acid as a weak acid was applied to both sides of the adsorptive sheet.
Weight% was impregnated and dried. Next, 5% by weight of malic acid was attached to one surface of the adsorptive sheet and dried to obtain an adsorptive sheet.

Example 4 On one surface of the sheet (a),
5 wt% of a paste having a viscosity of 500 cps containing polyethyleneimine (molecular weight: 300) as an aldehyde gas adsorbent was impregnated and dried. Then on the same plane,
5% by weight of a paste having a viscosity of 500 cps containing malic acid as a weak acid was impregnated and dried.

Thereafter, polyethyleneimine (molecular weight: 3
00) was attached to the other surface of the adsorptive sheet by 5% by weight and dried. Then, 5% by weight of malic acid was used as a weak acid on the same surface and dried to obtain an adsorptive sheet.

(Example 5) On one side of the sheet (a), 5% by weight of a paste containing malic acid as a weak acid and having a viscosity of 500 cps was attached and dried. Then, 5% by weight of malic acid was used as a weak acid on the same surface and dried.

Then, polyethyleneimine (molecular weight: 30 was used as an adsorbent for the aldehyde gas on the same surface of the sheet.
0) containing 5% by weight of a paste having a viscosity of 500 cps
Impregnated and dried. Then, 5% by weight of polyethyleneimine (molecular weight: 300) was attached to the same surface and dried to obtain an adsorptive sheet.

(Comparative Example 1) The sheet (a) was used as it was.

Comparative Example 2 5% by weight of a paste having a viscosity of 500 cps containing malic acid as a weak acid was impregnated on the sheet (a) and dried. Next, 5% by weight of malic acid was attached to the adsorptive sheet and dried to obtain an adsorptive sheet.

Comparative Example 3 Polyethyleneimine (molecular weight: 3) was added to the sheet (a) as an adsorbent for aldehyde gas.
5% by weight of a paste containing 00) having a viscosity of 500 cps was impregnated and dried. Next, 5% by weight of polyethyleneimine (molecular weight: 300) was attached to the adsorptive sheet and dried to obtain an adsorptive sheet.

Comparative Example 4 5% by weight of a paste having a viscosity of 500 cps containing aminoethylethanolamine as an aldehyde gas adsorbent was impregnated on the sheet (a) and dried. Next, 5% by weight of aminoethylethanolamine was attached to the adsorptive sheet and dried to obtain an adsorptive sheet.

(Comparative Example 5) A paste having a viscosity of 500 cps, which was adjusted to pH 7 with malic acid, of polyethyleneimine (molecular weight: 300) as an adsorbent for an acidic substance was attached to the sheet (a) and dried to obtain an adsorbent sheet. Obtained. The amount of polyethyleneimine and malic acid attached to the adsorptive sheet was 5% by weight, respectively.

(Evaluation of deodorizing performance) The deodorizing performance was evaluated by mounting an adsorbent sheet on an air purifier in an acrylic 1 m ³ box and operating the air purifier to determine the equilibrium adsorption amount of acetaldehyde gas. It was The samples used for the measurement were stored in the atmosphere within 10 days, 90 days and 180 days after the attachment. Table 1 shows the results.

The measurement was carried out with air containing 5 ppm of acetaldehyde in a 1 m ³ box (temperature: 25 ° C., relative humidity: 50).
%) In a gas chromatograph with FID.

The adsorptive sheet used for deodorization evaluation is 0.05
m ^2, air volume and 190 m ³ / Hr, was calculated adsorption amount per 1 m ² from the adsorption amount per 0.05 m ^2.

[0045]

[Table 1]

As is clear from Table 1, the examples satisfying the requirements specified in the present invention had the most suitable characteristics as an absorptive sheet.

[0047]

The absorptive sheet of the present invention is constructed as described above, has an excellent deodorizing effect on aldehyde gas, and has a long-term stable adsorption that does not deteriorate in performance over time.
An absorptive sheet having excellent removability can be provided.

Claims (5)

[Claims] 1. An adsorbent sheet comprising an activated carbon material, wherein an aliphatic amine layer and a weak acid layer are provided on at least one surface layer of the sheet. 2. The adsorptive sheet according to claim 1, wherein the activated carbon material is fine particulate activated carbon. 3. The adsorptive sheet according to claim 1, wherein the aliphatic amine layer is at least one selected from the group consisting of polyalkyleneimines and ethanol amines. 4. The adsorptive sheet according to claim 1, wherein the weak acid layer is a layer containing an aliphatic carboxylic acid. 5. A method for producing an adsorptive sheet, comprising adhering a pasty compound containing an aliphatic amine to an adsorptive sheet containing an activated carbon material and then adhering a weakly acidic compound.