JP3235092B2 - Basic gas absorbing fiber and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a basic gas absorbing fiber capable of reversibly absorbing and releasing a basic gas, having a high absorption rate, and enduring repeated use, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, odors have become a problem due to changes in lifestyles, densification of living environments, and increased confidentiality, and demands for odors have been increasing. Among them, basic gases such as ammonia and trimethylamine are regarded as typical malodorous components along with hydrogen sulfide and methyl mercaptan.

[0003] As deodorizing fibers, those in which a deodorant substance is adhered and fixed on the fiber surface, activated carbon fibers and the like are known.
The former has problems in durability and texture, the latter has problems in price and deodorizing performance against ammonia, and has the disadvantage of requiring high temperature for regeneration or chemicals in the case of chemical regeneration. I have. As deodorizing fibers for basic gas, those utilizing a deodorizing mechanism by a neutralization reaction are widely known. However, fibers obtained by attaching a substance involved in the reaction to fibers by post-processing are basically large deodorizing fibers. No odor ability is obtained. Also, as a method of introducing a functional group into the fiber,
There is a method of introducing a carboxyl group into acrylic fiber, but with this method, fiber properties are deteriorated by increasing the number of functional groups, so that a large deodorant ability that combines mechanical fiber properties has not been obtained. This is the actual situation.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a basic gas having a large amount of absorption, a high absorption rate, easy handling, and mechanical properties capable of being easily processed into various forms. Another object of the present invention is to provide a basic gas-absorbing fiber which can be easily regenerated and a method for producing the same.

[0005]

The object of the present invention is to increase the nitrogen content by hydrazine crosslinking from 1.0 to 8.
0% by weight of the crosslinked acrylic fiber, and 2.0 to 6.0 mmol / g, preferably 3.0 to
A carboxyl group of 6.0 mmol / g, and an amide group introduced into the remainder, achieved by a basic gas-absorbing fiber having a tensile strength of 1 g / d or more and a production method according to claim 2. Is done.

The present invention is a crosslinked acrylic fiber. The starting acrylic fiber is acrylonitrile (hereinafter referred to as AN) in an amount of 40% by weight or more, preferably 50% by weight.
It is a fiber formed by the AN polymer contained above, and may be in any form such as a short fiber, a tow, a yarn, a knitted woven fabric, a nonwoven fabric, or an intermediate product in a manufacturing process, a waste fiber, or the like. The AN-based polymer may be either an AN homopolymer or a copolymer of AN and another monomer. Examples of the other monomer include vinyl halide and vinylidene halide; (meth) acrylate (and (meth) acrylate). Represents both those with and without the meta)); sulfonic acid-containing monomers such as methallyl sulfonic acid and p-styrene sulfonic acid and salts thereof; (meth) acrylic acid, itaconic acid, etc. And other salts such as acrylamide, styrene and vinyl acetate. The means for producing the starting acrylic fiber is not limited, and any known means may be used as appropriate.

As a method of introducing hydrazine crosslinking into the acrylic fiber, any method can be adopted as long as the increase in nitrogen content can be adjusted to 1.0 to 8.0% by weight, but an aqueous solution having a hydrazine concentration of 6 to 80% by weight can be used. At a temperature of 50-120 ° C 1 ~
Means of treating for 5 hours are industrially preferred. Here, the increase in the nitrogen content refers to the difference between the nitrogen content of the raw acrylic fiber and the nitrogen content of the hydrazine cross-linked acrylic fiber. If the increase in the nitrogen content is less than the lower limit, fibers having practically satisfactory physical properties cannot be finally obtained. On the other hand, when the ratio exceeds the upper limit, a sufficient absorption capacity of the basic gas cannot be finally obtained. In the present invention, the increase is 1.0 to 8.
The condition of 0% by weight can be easily determined by clarifying the relationship between the reaction factors such as the reaction temperature, concentration, and time and the increase in the nitrogen content through experiments. Examples of the hydrazine used here include hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, hydrazine bromate and the like.

Next, a method of substantially eliminating a nitrile group remaining without hydrazine crosslinking by a hydrolysis reaction and introducing an amide group to a carboxyl group of 2.0 to 6.0 mmol / g and the remainder is as follows. And a means for impregnating a basic aqueous solution such as an alkali metal hydroxide or ammonia, or an aqueous solution such as nitric acid, sulfuric acid, or hydrochloric acid, or performing a heat treatment with the raw material fibers immersed in the aqueous solution. As for the conditions under which the amount of carboxyl groups of the present invention is 2.0 to 6.0 mmol / g, the relationship between reaction factors such as reaction temperature, concentration, and time and the amount of carboxyl groups introduced is clarified by experiments. Can be easily determined. In addition, a hydrolysis reaction can be performed simultaneously with the introduction of the cross-linking. Here, when hydrolyzed with a base, it is necessary to convert the carboxyl group to H-form.

As a method for converting the carboxyl group into the H-form, a method is preferably used in which the above-mentioned hydrolyzed fiber is immersed in various acidic aqueous solutions exemplified below, and then dried. Examples of the acidic aqueous solution include aqueous solutions of hydrochloric acid, acetic acid, nitric acid, sulfuric acid and the like.

When the carboxyl group is less than the above lower limit, the same level of absorption capacity as activated carbon as a typical deodorant cannot be obtained, and when the carboxyl group exceeds the upper limit, practically satisfactory fiber properties are obtained. I can't.

In this way, the tensile strength is 1 g / d or more, the basic gas absorption capacity is excellent, the absorption speed is high, and
As will be described later, a fiber that can be easily regenerated can be provided. That is, this basic gas absorption reaction is a reversible reaction, and the amount of gas absorbed per unit amount of the fiber is determined in accordance with the basic gas concentration in the atmosphere. Released by
The absorption capacity of the fiber can be easily regenerated.

Here, when a particularly high tensile strength is required, it is preferable to select a fiber having a high dichroic ratio as the starting acrylic fiber as described later.

[0013] The means for filling the acrylic fiber into a container provided with a pump circulation system and successively introducing the above-mentioned cross-linking and carrying out the hydrolysis reaction is required in terms of safety, uniform reactivity, etc. on the apparatus. desirable. A typical example of such an apparatus (a container provided with a pump circulation system) is an Overmeyer dyeing machine.

In order to provide a fiber having practically no problem in fiber physical properties and a high basic gas-absorbing ability, it is particularly desirable to use a starting acrylic fiber having the following properties. That is, it is desirable to select an acrylic fiber in which the AN polymer molecules forming the fiber are sufficiently oriented and the dichroic ratio of Congo Red (hereinafter referred to as CR) is 0.4 or more, more preferably 0.5 or more. Note that CR
The dichroic ratio is determined according to the method described in Kobunshi Kagaku 23 (252) 193 (1966).

The means for producing such acrylic fibers is not limited, and any known means can be used as long as the above-mentioned CR dichroic ratio is satisfied. A desired acrylic fiber can be produced industrially and advantageously by adopting a means that is at least 8 times and the process shrinkage is at most 30%, preferably at most 20%.

Further, as a starting acrylic fiber, a fiber after drawing and before heat treatment (a spinning stock solution of an AN polymer is spun according to a conventional method and drawn and oriented, but is subjected to dry densification, wet heat relaxation treatment). Dispersibility of the fibers in the reaction solution by using fibers that have not been subjected to heat treatment, such as wet or dry / wet spinning and water-swelled gel-like fibers after stretching: the degree of water swelling is 30 to 150%. This is desirable because the permeability of the reaction solution into the fiber is improved, and the introduction of cross-linking and the hydrolysis reaction are performed uniformly and promptly. Needless to say, the degree of water swelling is a percentage of the amount of contained or attached water expressed on a dry fiber weight basis.

[0017]

The reason why the basic gas-absorbing fiber of the present invention and the manufacturing method have a high basic gas-absorbing ability and also have yarn physical properties has not been sufficiently elucidated, but is considered as follows. Can be

That is, since the fiber according to the present invention is substantially free of nitrile groups while starting from an AN polymer, the side chain bonded to the polymer chain reacts with hydrazine. And a carboxyl group generated by a hydrolysis reaction of a nitrile group. The reason that the fiber absorbs the basic gas may be that the carboxyl group and the basic gas are combined by an acid-base reaction. Since the acid-base reaction is a reversible reaction, the absorption capacity of the fiber is easily regenerated. Here, it was possible to have both high basic gas absorption capacity and yarn physical properties because of the cross-linking structure inside, so that nitrile, which is essential for forming acrylic fiber yarns, Even if the group is lost and converted to a carboxyl group,
The yarn properties will be maintained.

Further, the processing performance is likely to be largely attributable to the orientation structure seen in the CR dichroism ratio.

[0020]

The present invention will be described in detail with reference to the following examples. The percentages in the examples are given on a weight basis unless otherwise specified. All gas absorption experiments were performed under atmospheric pressure (1 atm).

The carboxyl group content and basic gas absorption capacity were determined by the following methods.

(1) Carboxyl group content (m mol / g) 1 g of sufficiently dried test fiber was precisely weighed (Ag), and 200 ml
Was added thereto, and the mixture was adjusted to pH 2 by adding a 1N aqueous hydrochloric acid solution while heating to 50 ° C., and a titration curve was obtained with a 0.1N aqueous sodium hydroxide solution according to a conventional method. From the titration curve, the consumption amount (Bcc) of the aqueous sodium hydroxide solution consumed by the carboxyl group was determined,
The carboxyl group content was calculated by the following equation. (Amount of carboxyl group (m mol / g)) = 0.1B / A

(2) Basic Gas Absorbing Capacity A predetermined amount of dried test fiber is placed in a container having a predetermined capacity, and
Temperature and humidity are controlled at ℃ and relative humidity of 65%. After that, the container is sealed and a basic gas is injected so as to have a predetermined concentration.
After being left under the above conditions, the gas concentration in the container was measured by a gas detection tube or a method described later. From the difference between the residual gas concentration and the initial gas concentration, the gas absorption capacity of the fiber was evaluated. The measurement of the high-concentration ammonia concentration was performed as follows. The gas in the container is collected (Cml), shaken with water, and the ammonia in the gas is dissolved in the water.
This aqueous solution is titrated with 0.01N hydrochloric acid, and the amount of liquid required for neutralization
(Dcc). From these results, the ammonia gas concentration was calculated by the following equation. (Ammonia gas concentration (ppm)) = D × (gas amount per mol at the measurement temperature (lt)) / C × 10 ⁴

AN 90% and methyl acrylate (hereinafter referred to as M
A) 10% of an AN polymer (intrinsic viscosity [η] in dimethylformamide at 30 ° C .: 1.2) of 10% was dissolved in 90 parts of a 48% aqueous solution of rodan soda, and a spinning stock solution was spun and drawn according to a conventional method. (Total stretching ratio: 10 times), then dry ball /
Wet bulb = Dry under an atmosphere of 120 ° C / 60 ° C (process shrinkage 14%)
Raw fiber I with a single fiber fineness of 1.5 d (CR dichroic ratio 0.58)
I got

The raw fiber I was subjected to a hydrazine treatment and a hydrolysis treatment under the conditions shown in Table 1, and was immersed in a 1N hydrochloric acid aqueous solution for 30 minutes to carry out an acid treatment. This was dehydrated, washed with water, and dried to obtain Fiber Nos. 1 to 7. Table 1 shows the characteristic values of the obtained fibers.
Table 2 shows the basic gas absorption capacity. The measurement conditions are as follows. Ammonia: Gas initial concentration 2000ppm, fiber weight 0.3g, container capacity 1400ml. Trimethylamine:
Gas initial concentration 100ppm, fiber weight 6g, container capacity 3lt.

[0026]

[Table 1]

[0027]

[Table 2]

It can be seen that the fibers Nos. 1 to 4 of the present invention are fibers having both excellent basic gas absorbing ability and fiber physical properties. In contrast, Comparative Example Fiber No. 5, in which the amount of nitrogen increased by hydrazine treatment was small, had excellent basic gas absorption capacity, but had a low tensile strength of 0.8 g / d and was brittle. It did not have physical properties to withstand processing. Fiber No. 6 with insufficient hydrolysis treatment and Fiber No. 7 with insufficient hydrolysis due to excessive crosslinking treatment have low basic gas absorption capacity due to a small amount of carboxyl groups. Met.

Example 2 The ammonia absorption rate of the fiber No. 1 obtained in Example 1 was evaluated by measuring the ammonia gas concentration over time. The fiber weight was 0.3 g, the initial concentration of ammonia gas was 10000 ppm, and the container capacity was 1400 ml. The results are shown in FIG.

[0030]

FIG.

At 20 ° C. and 65% relative humidity, the concentration of airborne ammonia reached a parallel value in less than 20 minutes, indicating that the absorption rate was very fast.

Example 3 After measuring the ammonia gas absorption capacity of the fiber No. 1 obtained in Example 1, the fiber was dried for 3 hours and then again measured for absorption capacity. This operation was repeated three times, and the regeneration ability of the fiber was examined. In addition, fiber weight 0.46g, ammonia gas initial concentration
It was 44000 ppm and the container capacity was 1400 ml. Table 3 shows the results.

[0033]

[Table 3]

Although the absorption capacity is reduced to about 80% by the regeneration, it can be seen that the capacity does not change after the second regeneration, and that it is easily regenerated by sun drying.

Example 4 Example 1 except that vinylidene chloride was used instead of MA.
The raw material fiber II (CR dichroic ratio 0.55) was obtained in the same manner as described above.
This was treated in the same manner as in Fiber No. 1 of Example 1.

The obtained fiber had a nitrogen increase of 4.0%, a carboxyl group content of 4.8 mmol / g, and a tensile strength of 1.6 g / d. The basic gas absorption capacity according to the above-described method was measured in the container after absorption under the above measurement conditions. The gas concentration of ammonia was not detected, and trimethylamine was 49 ppm. Thus, it was an excellent basic gas-absorbing fiber having fiber physical properties.

[0037]

With the advent of the present invention, it is possible to provide a fiber having an excellent basic gas absorption capacity and a means for producing the fiber in an industrially advantageous manner while maintaining fiber properties which are practically satisfactory. Are the remarkable effects of the present invention. Such fiber is, for example, 30% per kg-fiber if it is ammonia gas.
It shows the ability to absorb ~ 100gr.

The basic gas-absorbing fiber of the present invention can be easily regenerated by placing it in clean air even after it has been saturated and absorbed, and can be used repeatedly.
Further, since it is fibrous and can be processed into various forms such as a nonwoven fabric, a woven fabric, a knitted fabric, a paper, or a flocking on a substrate, it is widely used in various application fields which require absorption of a basic gas. For example, water purification elements such as filter for appreciation fish and fish tank-filter for bath-filter for wastewater treatment-
In addition to air conditioner elements such as air conditioner filters, air purifier filters, clean room air filters, dehumidifier filters, and commercial basic gas treatment filters, clothing such as underwear and socks Bedding, pillows, sheets, blankets, cushions and other bedding, curtains, carpets,
Interior goods such as mats, wallpapers, stuffed animals, artificial flowers, artificial trees, etc., hygiene materials such as masks, incontinence shorts, wet tissues, etc., car seats, interior goods such as interiors, toilet covers,
Toilet articles such as toilet mats, pet restrooms, kitchenware such as refrigerators and garbage cans, linings for shoes, slippers, gloves, towels, rags, rubber gloves, rubber boots, adhesives, garbage disposal And the like.

The fiber can be used alone or of course, but it can be more effectively used in the above fields by blending or mixing with other fibers. For example, when used as a batting or nonwoven fabric such as a futon, by blending with other fibers such as polyester, performance such as bulkiness is imparted. In addition, by using a mixture with another absorbent such as an acidic gas absorbent, an absorbent for a wider range can be obtained. Thus, for the purpose of providing other functions, and for the purpose of reducing the mixing ratio of the fiber,
In addition, it can be used in combination with various kinds. Further, as an ion exchanger, it can be used for a water treatment agent, a metal adsorbent, and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing the ammonia absorption rate of the fiber of the present invention expressed by the ammonia concentration in a test gas with respect to the elapsed time.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI D06M 11/38 D06M 3/18 // D06M 101: 28 3/20 11/04 G

Claims (2)

(57) [Claims] 1. A crosslinked acrylic fiber in which the increase in nitrogen content due to hydrazine crosslinking is 1.0 to 8.0% by weight, and a carboxyl group of 2.0 to 6.0 mmol / g is partially contained in a residual nitrile group and a carboxyl group in a remaining part. Has an amide group introduced, 1 g / d
A basic gas absorbing fiber having the above tensile strength. 2. A crosslink is introduced into the acrylic fiber by hydrazine treatment to adjust the increase in nitrogen content to a range of 1.0 to 8.0% by weight, and a hydrolysis reaction causes the remaining nitrile group to be 2.0 to 6.0% by weight. A method for producing a basic gas-absorbing fiber, wherein a carboxyl group is introduced into mmol / g and an amide group is introduced into the remainder.