JPH08246342A - Basic gas-absorbing fiber and its production - Google Patents

Abstract

PURPOSE: To obtain a basic gas-absorbing fiber which shows a large absorption and high absorption rate of basic gas, has sufficient mechanical properties and can be readily regenerated, by specifying the increase of nitrogen content by hydrazine crosslinking and introduction of carboxyl groups and amide groups into the fiber. CONSTITUTION: An acrylic fiber produced from an acrylonitrile(AN) polymer containing more than 40wt.% of AN is crosslinked with hydrazine to increase the nitrogen content by 1.0-8.0wt.% by means of the hydrazine crosslinking. Then, the fiber is hydrolyzed to eliminate the residual nitrile group and introduce 2.0-6.0mmol/g of carboxyl groups and amide groups to the rest part to give this fiber with the tensile strength of higher than 1g/d, having excellent absorption power of basic gas.

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 which can reversibly absorb and release a basic gas, has a fast absorption rate, and can withstand repeated use, and a method for producing the same.

[0002]

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

Known deodorant fibers include deodorant substances adhered and fixed to the fiber surface and activated carbon fibers.
The former has problems in durability and texture, and the latter has problems in price and deodorizing performance against ammonia, and also has a drawback that requires high temperature for regeneration or requires chemicals for chemical regeneration. There is. Many deodorant fibers that utilize a deodorizing mechanism due to a neutralization reaction are known as deodorizing fibers for basic gas, but those obtained by attaching a substance related to the reaction to the fibers by post-processing are basically large deodorizing fibers. The odor ability cannot be obtained. Further, as a method of introducing a functional group into the fiber,
There is a method of introducing a carboxyl group into the acrylic fiber, but in this method the physical properties of the fiber are deteriorated by increasing the number of functional groups, so a deodorant ability with mechanical fiber properties has not been obtained. Is the actual situation.

[0004]

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

[0005]

The above-mentioned object of the present invention is to increase the nitrogen content by hydrazine crosslinking to 1.0 to 8.
0% by weight of the cross-linked acrylic fiber, 2.0-6.0 mmol / g, preferably 3.0-
Achieved by the basic gas-absorbing fiber having a tensile strength of 1 g / d or more in which a carboxyl group of 6.0 mmol / g and an amide group are introduced in the balance, and the manufacturing method according to claim 2. To be done.

The present invention is a crosslinked acrylic fiber, and the starting acrylic fiber thereof is 40% by weight or more, preferably 50% by weight, of acrylonitrile (hereinafter referred to as AN).
It is a fiber formed from the AN-based polymer contained above, and may be in any form such as short fiber, tow, yarn, knitted woven fabric, non-woven fabric, etc., and may be intermediate product in the manufacturing process, waste fiber or the like. The AN polymer may be either an AN homopolymer or a copolymer of AN and another monomer, and as the other monomer, vinyl halide and vinylidene halide; (meth) acrylic acid ester (note that (meth)) 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. Carboxylic acid-containing monomers and salts thereof; other monomers such as acrylamide, styrene, vinyl acetate and the like. There is no limitation on the means for producing the starting acrylic fiber, and any known means may be used as appropriate.

As a method for introducing hydrazine crosslinks 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 is used. , 1 to 50 ~ 120 ℃
Means for treating for 5 hours is industrially preferable. Here, the increase of the nitrogen content means the difference between the nitrogen content of the raw acrylic fiber and the nitrogen content of the hydrazine-crosslinked acrylic fiber. When the increase in the nitrogen content is less than the lower limit, finally, fibers having physical properties that are practically satisfactory cannot be obtained. On the other hand, when the amount exceeds the upper limit, a sufficient absorption capacity for basic gas cannot be finally obtained. According to the present invention, the increase is 1.0 to 8.
The condition of 0 wt% can be easily determined by clarifying the relationship between the reaction factors such as reaction temperature, concentration and time and the increase of nitrogen content in the experiment. Examples of the hydrazine used here include hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, and hydrazine bromate.

Next, as a method of substantially eliminating the nitrile group remaining without being cross-linked with hydrazine by a hydrolysis reaction, and introducing a carboxyl group of 2.0 to 6.0 mmol / g and an amide group to the rest. A method of impregnating a basic aqueous solution of alkali metal hydroxide, ammonia or the like, or an aqueous solution of nitric acid, sulfuric acid, hydrochloric acid or the like, or heat-treating the raw material fibers in a state of being immersed in the aqueous solution. Regarding the condition that the amount of the carboxyl group which is the present invention is 2.0 to 6.0 mmol / g, the temperature of the reaction, the concentration, by clarifying the relationship between the amount of the carboxyl group to be introduced and the reaction factor such as the reaction factor by the experiment Can be easily determined. The hydrolysis reaction can be carried out simultaneously with the introduction of the cross-linking bond. Here, when hydrolyzed with a base, it is necessary to make the carboxyl group H-type.

As a method for converting the carboxyl group to the H-type, a method of immersing the above-mentioned hydrolyzed fiber in various acidic aqueous solutions exemplified below and then drying is suitably used. Examples of the acidic aqueous solution include aqueous solutions of hydrochloric acid, acetic acid, nitric acid, sulfuric acid and the like.

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

Thus, the tensile strength is 1 g / d or more, the basic gas absorption capacity is excellent, the absorption rate is high, and
As described below, it is possible to provide a fiber that can be easily regenerated. 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 according to the concentration of basic gas in the atmosphere. Therefore, once absorbed the basic gas, apply clean air. Released by
The absorption capacity of the fiber can be easily regenerated.

Here, when 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.

A means for filling acrylic fiber into a container equipped with a pump circulation system and successively introducing the above-mentioned cross-linking and the hydrolysis reaction is from the viewpoint of safety, uniform reactivity, etc. in terms of equipment. desirable. A typical example of such a device (a container equipped with a pump circulation system) is an Overmeier dyeing machine.

Further, in order to provide a fiber having both practically no problematic physical properties and a high basic gas absorption capacity, it is desirable to employ 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 Congo red (hereinafter referred to as CR) dichroic ratio is 0.4 or more, more preferably 0.5 or more. In addition, CR
The dichroic ratio is determined according to the method described in Polymer Chemistry 23 (252) 193 (1966).

There is no limitation on the means for producing such acrylic fibers, and any known means can be used as long as the above-mentioned CR dichroic ratio is satisfied, but among them, the total draw ratio is 6 times or more, preferably. The desired acrylic fiber can be produced industrially advantageously by adopting a means for making the process shrinkage rate 8 times or more and the process shrinkage rate 30% or less, preferably 20% or less.

Further, as the starting acrylic fiber, the fiber after stretching and before heat treatment (spinning solution of AN polymer is spun according to a conventional method and stretched and oriented, but it is dried and densified and subjected to heat and moisture relaxation treatment). Dispersibility of the fibers in the reaction solution by using fibers that have not been heat treated, such as wet or dry / wet spinning, and water-swollen gel fibers after stretching: water swelling degree of 30 to 150%) In addition, the permeability of the reaction solution into the fiber is improved, and thus the introduction of cross-linking and the hydrolysis reaction are carried out uniformly and quickly, which is desirable. Needless to say, the degree of water swelling is the percentage of the content or adhered water content expressed on the basis of dry fiber weight.

[0017]

The reason why the basic gas absorbing fiber and the method for producing the same according to the present invention have a high basic gas absorbing ability and combine the physical properties of yarns has not yet been fully clarified, but it is generally considered as follows. To be

That is, although the fiber according to the present invention starts from an AN polymer, the nitrile group is substantially eliminated, so that the side chain bonded to the polymer chain reacts with hydrazine. It is considered to be a nitrogen-containing crosslinked structure produced by the above and a carboxyl group produced by the hydrolysis reaction of the nitrile group. The reason why the fiber absorbs the basic gas may be that the carboxyl group and the basic gas are bonded by the acid-base reaction. Since this acid-base reaction is a reversible reaction, the absorption capacity of the fiber is easily regenerated. Here, it was possible to have both a high basic gas absorption capacity and thread properties because it has a cross-linked structure inside, and thus it is essential to form the thread of acrylic fiber. Even if the group is lost and converted to a carboxyl group,
The thread properties will be retained.

The processing performance is largely supported by the orientation structure seen in the CR dichroic ratio.

[0020]

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

The amount of carboxyl groups and basic gas absorption capacity were determined by the following methods.

(1) Amount of carboxyl group (m mol / g) 1 g of sufficiently dried test fiber was precisely weighed (Ag), and 200 ml was added to this.
After the addition of water, the pH was adjusted to 2 by adding a 1N hydrochloric acid aqueous solution while heating at 50 ° C., and a titration curve was determined using a 0.1N caustic soda aqueous solution by a conventional method. From the titration curve, calculate the amount of caustic soda aqueous solution consumed (Bcc) consumed by the carboxyl group,
The amount of carboxyl groups was calculated by the following formula. (Amount of carboxyl group (m mol / g)) = 0.1B / A

(2) Basic gas absorption capacity A predetermined amount of dried test fiber is put in a container having a predetermined capacity, and 20
Temperature and humidity control at ℃ and 65% relative humidity. After this, the container is closed and basic gas is injected to a predetermined concentration, and the mixture is left for 2 hours.
After standing under the above conditions, the gas concentration in the container was measured by a gas detector tube or a method described later. The gas absorption capacity of the fiber was evaluated by the difference between the residual gas concentration and the initial gas concentration. The high concentration ammonia was measured as follows. The gas in the container is sampled (Cml) and shaken with water to dissolve ammonia in the gas in water.
Titrate this aqueous solution with 0.01N hydrochloric acid to determine the amount of liquid required for neutralization.
Calculate (Dcc). From these results, the ammonia gas concentration was calculated by the following formula. (Ammonia gas concentration (ppm)) = D × (gas amount per 1 mol at measurement temperature (lt)) / C × 10 ⁴

90% AN and methyl acrylate (hereinafter M
A) A 10% AN polymer (intrinsic viscosity [η] in dimethylformamide at 30 ° C. [1.2]) of 10 parts was dissolved in 90 parts of 48% rhodasoda aqueous solution to prepare a spinning solution, which was then spun and stretched according to a conventional method. (Total draw ratio: 10 times), then dry bulb /
Wet bulb = 120 ° C / 60 ° C atmosphere drying (process shrinkage 14%)
And raw fiber I with a single fiber fineness of 1.5d (CR dichroic ratio 0.58)
I got

The raw material fiber I was treated with hydrazine and hydrolyzed under the conditions shown in Table 1, and immersed in a 1N hydrochloric acid aqueous solution for 30 minutes for 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.
The basic gas absorption capacity is shown in Table 2. The measurement conditions are as follows. Ammonia: Gas initial concentration 2000ppm, fiber weight 0.3g, container volume 1400ml. Trimethylamine:
Gas initial concentration 100ppm, fiber weight 6g, container volume 3lt.

[0026]

[Table 1]

[0027]

[Table 2]

It can be seen that the fibers Nos. 1 to 4 of the present invention have excellent basic gas absorbing ability and fiber physical properties. On the other hand, Comparative Fiber No. 5, which has a small increase in nitrogen due to hydrazine treatment, has an excellent basic gas absorption capacity, but has a low tensile strength of 0.8 g / d and is a brittle fiber. It did not have physical properties to withstand processing. In addition, the fiber No. 6 which is insufficiently hydrolyzed and the fiber No. 7 which is insufficiently hydrolyzed due to excessive crosslinking treatment have a 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 volume was 1400 ml. The results are shown in Fig. 1.

[0030]

[Figure 1]

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

Example 3 The ammonia gas absorption capacity of the fiber No. 1 obtained in Example 1 was measured, then the fiber was sun-dried for 3 hours, and the absorption capacity was measured again. This operation was repeated 3 times, and the regeneration ability of the fiber was examined. Fiber weight 0.46g, ammonia gas initial concentration
The volume was 44000ppm and the container volume was 1400ml. The results are shown in Table 3.

[0033]

[Table 3]

Although the absorption capacity becomes about 80% by the regeneration, it is understood 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 is used instead of MA.
Raw fiber II (CR dichroic ratio 0.55) was obtained in the same manner as
This was treated in the same manner as Fiber No. 1 of Example 1.

The fiber obtained had an increased nitrogen content 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 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, which was an excellent basic gas absorbing fiber having fiber properties.

[0037]

Industrial Applicability With the advent of the present invention, it is possible to provide a fiber having an excellent basic gas absorption capacity while maintaining the fiber physical properties that are practically unproblematic and a means for industrially producing the fiber. Is a remarkable effect of the present invention. For example, if the fiber is ammonia gas, it is 30 per kg-fiber.
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 saturated absorption, and can be repeatedly used.
Further, since it is fibrous and can be processed into various forms such as non-woven fabric, woven fabric, knitted fabric, paper, or flocking on a substrate, it is widely used in various fields of application in which basic gas absorption is required. For example, water purification elements such as filters for ornamental fish and fish tanks, filters for baths, filters for wastewater treatment,
Air conditioner filters, air purifier filters, clean room air filters, dehumidifier filters, commercial basic gas treatment filters, and other elements for air conditioning equipment, as well as clothing such as underwear and socks. Bedding, bedding, such as general, futon, pillow, sheet, blanket, cushion, katen, carpet,
Interior items such as mats, wallpaper, plush toys, artificial flowers, and trees, masks, incontinence shorts, hygiene materials such as wet tissues, car seats, interior items such as interior parts, toilet covers,
Toilet mats, toilet items such as pet toilets, refrigerators, kitchen items such as linings for dustbins, etc., insoles for shoes, slippers, gloves, towels, rags, linings for rubber gloves, linings for boots, patching materials, garbage disposal Examples include devices.

The fibers can be used alone or of course, but they can be more effectively used in the above-mentioned fields by mixing or spinning with other fibers. For example, when it is used as a batting or a non-woven fabric such as a futon, it is mixed with other fibers such as polyester and used to impart performances such as bulkiness. In addition, an absorbent for a wider range can be obtained by mixing it with another absorbent such as an acidic gas absorbent. Thus, for the purpose of imparting other functions, and for the purpose of lowering the mixing ratio of the fibers,
It can be used in combination with various other materials. Further, it can be used as a water treatment agent, a metal adsorbent or the like as an ion exchanger.

[Brief description of drawings]

FIG. 1 is a diagram showing the ammonia absorption rate by the fiber of the present invention as the concentration of ammonia in a test gas against the elapsed time.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location D06M 11/38 D06M 3/20 // D06M 101: 28 11/04 G

Claims (2)

[Claims] 1. A crosslinked acrylic fiber having an increase in nitrogen content by hydrazine crosslinking of 1.0 to 8.0% by weight, wherein 2.0 to 6.0 mmol / g of carboxyl groups are contained in the balance of the remaining nitrile groups. Has an amide group introduced, 1g / d
A basic gas absorbing fiber having the above tensile strength. 2. A crosslinkage is introduced into acrylic fiber by hydrazine treatment to adjust the increase of nitrogen content in the range of 1.0 to 8.0% by weight, and by hydrolysis reaction, 2.0 to 6.0 of the remaining nitrile group is introduced. A method for producing a basic gas-absorbing fiber, which comprises introducing a carboxyl group into m mol / g and an amide group into the rest.