JP3191278B2 - pH buffering fiber and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to the pH of water in contact with fibers.
The present invention relates to a pH-buffering fiber having a function of maintaining pH 5 to a weak acidity of pH 5 to 7 (hereinafter, simply referred to as weak acidity) and a method for producing the same.

[0002]

2. Description of the Related Art Under normal conditions, human skin is kept weakly acidic due to secreted lactic acid and the like, but the pH of the skin is reduced due to acid rain accompanying the recent environmental destruction and alkalinization of clothes due to washing. Beyond the normal range, this undermines healthy skin. In order to keep the pH of the skin weakly acidic, it is desirable that the external acid or alkali be neutralized by clothing and that the fiber material itself in contact with the skin be weakly acidic. As a method for responding to such a demand, there is a method in which a protein having a weakly acidic isoelectric point is attached to textiles by post-processing. However, this method has a drawback that it cannot be easily processed into various forms because a pH buffering substance is attached to textiles by post-processing, and flame retardancy, which is recently increasing as a social need, It did not satisfy antibacterial properties and moisture absorption / release properties.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a weakly acidic pH buffer having a large capacity, being durable, not impairing the texture of the product, and being easily processed into various forms, and further having flame retardancy. An object of the present invention is to provide a pH buffering fiber having antibacterial properties and hygroscopicity and a method for producing the same.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention that the increase in nitrogen content by hydrazine crosslinking is 1.0 to 1.0.
The crosslinked acrylic fiber is 8.0% by weight, and a carboxyl group of 2.5 to 4.5 meq / g is introduced into one part of the remaining nitrile group, and an amide group is introduced into the remaining part. Has one or two or more metals selected from Ca, Mg, and Al as essential components, and an equivalent ratio (metal to H) of 1.0 to 1.5 to 4.0. PH buffering fiber characterized by being in the range of 1.0 to 1.0
Also, a cross-linking is introduced into the acrylic fiber by hydrazine treatment to adjust the increase in the nitrogen content within a range of 1.0 to 8.0% by weight, and the amount of the nitrile group remaining by the hydrolysis reaction is 2%. After introducing a carboxyl group to the remainder at an amount of 0.5 to 4.5 meq / g, an amide group is introduced immediately after the acid hydrolysis, and the carboxyl group is converted into the H-form with an acid during the alkaline hydrolysis. PH buffering characterized by adding one or more metal hydroxides selected from, Mg and Al to adjust the pH to 5.0 to 7.0 and converting a part to a metal salt form. A method for producing fibers.

Hereinafter, the present invention will be described in detail. First, the present invention is a crosslinked acrylic fiber, and acrylonitrile (hereinafter referred to as AN) is used as the starting acrylic fiber.
AN containing 0% by weight or more, preferably 50% by weight or more
It is a fiber formed by a system polymer, short fiber, tow,
Any form such as a yarn, a knitted fabric, a nonwoven fabric, or the like, or a product in the course of the manufacturing process, a waste fiber, or the like may be used. The AN-based polymer may be any of an AN homopolymer and a copolymer of AN and another monomer. Examples of the other monomer include vinyl halide and vinylidene halide; (meth) acrylate, methallyl sulfone. Sulfonic acid-containing monomers such as acid and p-styrenesulfonic acid and salts thereof; carboxylic acid group-containing monomers such as (meth) acrylic acid and itaconic acid and salts thereof; and other monomers such as acrylamide, styrene, and vinyl acetate. .

As a method for introducing hydrazine crosslinking into the acrylic fiber, an increase in the nitrogen content is 1.0 to 8.0.
Any means can be used as long as the means can be adjusted to the weight%, but means for treating at a concentration of 6 to 80% by weight and a temperature of 50 to 130 ° C. for 1 to 8 hours is industrially preferable. 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.

[0007] If the increase in the nitrogen content is less than the above lower limit, fibers having physical properties satisfactory for practical use cannot be finally obtained, and flame retardancy and antibacterial properties cannot be obtained. If it exceeds the upper limit, moisture absorption / release properties and pH buffering properties cannot be obtained, and neither of them achieves the object of the invention. Examples of the hydrazine that can be employed here include hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, hydrazine nitrate, and hydrazine bromate.

Further, the nitrile group remaining without hydrazine crosslinking is substantially eliminated by the hydrolysis reaction, and finally, a carboxyl group of 2.5 to 4.5 meq / g and an amide group are introduced into the remainder. Examples of the method include a method of impregnating with a basic aqueous solution of an alkali metal hydroxide or ammonia, or an aqueous solution of a mineral acid such as nitric acid, sulfuric acid, or hydrochloric acid, or performing a heat treatment in a state where the raw material fibers are immersed in the aqueous solution. No. In addition, a hydrolysis reaction can be performed simultaneously with the introduction of the cross-linking. Here, if the amount of carboxyl groups is less than the lower limit in the end, a practically satisfactory pH buffering capacity cannot be obtained, and further, flame retardancy, antibacterial properties, and moisture absorption / release properties cannot be obtained. On the other hand, if it exceeds the upper limit, fibers having practically satisfactory physical properties cannot be obtained.

The carboxyl group thus introduced is one or more selected from Ca, Mg and Al as essential components.
As a method of adjusting the equivalence ratio of at least one kind of metal to H (metal to H) from 1.0 to 1.5 to 4.0 to 1.0, when the above-mentioned hydrolysis is performed with an acid, After immersing the fiber in water, one or more metal hydroxides selected from Ca, Mg, and Al as essential components are added, and the pH is adjusted to 5.0.
Adjusted to 7.0, followed by washing with water and drying. When hydrolysis is carried out with an alkali, the total amount of carboxyl groups is converted into H-form by acid treatment, and then one or more metal hydroxides selected from Ca, Mg, and Al are added as essential components. Then, a method of adjusting the pH to 5.0 to 7.0, followed by washing with water and drying is used.

[0010] Metal salt-type carboxyl groups other than Ca, Mg, and Al cannot be used because they cannot buffer the pH to a weak acidity, or are harmful to the human body, and have wastewater contamination due to washing. For example, alkali metal salts such as Na, K, and Li have a pH buffering ability, but become alkaline when the pH is 7 or more. If the ratio between the H type and the metal salt type is increased in order to avoid this, the buffering property against acid is reduced, and the fiber is not a pH buffering fiber having a substantially weakly acidic buffering capacity. Next, a Ca, Mg, Al metal salt type carboxyl group and H
When the ratio of the type carboxyl group is less than the lower limit of the above range, there is no buffering property against acid, and when the ratio exceeds the upper limit, the buffering property against alkali is small and practically not a pH buffering fiber having a weakly acidic buffering capacity. Cannot achieve the invention. In the above description, C is used as the seed of the metal salt.
It is essential that any one of a, Mg, and Al is adopted, but other metals can be used as long as pH buffering property, flame retardancy, antibacterial property, and moisture absorption / release property are not impaired. However, its content is at most 0.4 meq / g as a metal salt type carboxyl group.

In this way, it is possible to provide a fiber having a flame resistance, an antibacterial property and a high hygroscopic property having a tensile strength of not less than 1 g / d and a weakly acidic pH buffering property. In particular, when a 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.

The means for filling the acrylic fiber into a container provided with a pump circulation system and sequentially performing the above-described cross-linking introduction, hydrolysis reaction, and metal salt formation reaction is a safety measure in the apparatus. It is desirable from various points such as properties and uniform reactivity. 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 properties, pH buffering property, flame retardancy, antibacterial property and moisture absorption / desorption property, a starting acrylic fiber particularly having the following properties is used. It is desirable to do.

That is, the AN polymer molecules forming the fibers are sufficiently oriented and Congo Red (hereinafter referred to as CR)
It is desirable to adopt an acrylic fiber having a dichroic ratio of 0.4 or more, more preferably 0.5 or more. The CR dichroism ratio was determined by Polymer Chemistry 23 (252) 193 (196).
6) It is determined according to the method described.

There are no particular limitations 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. A desired acrylic fiber can be produced industrially and advantageously by adopting a means that is 8 times or more and the process shrinkage is 30% or less, preferably 20% or less.

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

[0017]

The reason why the pH buffering fiber and the production method according to the present invention have flame retardancy, antibacterial properties and moisture absorption / release properties and also have pH buffering properties has not been sufficiently elucidated, but is generally as follows. Can be considered.

That is, while the fiber according to the present invention starts from an AN-based polymer, the side chain bonded to the polymer chain is reacted with hydrazine from the point where the nitrile group is substantially eliminated. It is considered that the nitrogen-containing crosslinked structure generated by the above and the H-type and metal salt-type carboxyl groups and amide groups generated by the hydrolysis reaction of the nitrile group.

In general, salt-type carboxyl groups have a pH buffering property, but in the present application, a specific ratio of a carboxyl group of a metal salt form of Ca, Mg, or Al to an H-form shows a weakly acidic buffering property because of a weak base. This is because the metal salt and weak acid coexist moderately. Flame retardancy is due to the crosslinked structure and acrylamide.
Antimicrobial properties are presumed to be provided by the crosslinked structure.

Further, the moisture absorption / desorption properties may be due to the crosslinked structure and the metal salt type carboxyl group. The processing performance is likely to be largely attributable to the orientation structure seen in the CR dichroism ratio.

[0021]

The present invention will be described in detail with reference to the following examples. Parts and percentages in the examples are by weight unless otherwise specified.

The pH buffer capacity (μeq / g), the total amount of carboxyl groups, the amount of metal salt-type carboxyl groups, the amount of H-type carboxyl groups (meq / g), LOI (limit oxygen index), moisture absorption and antibacterial properties ( The sterilization rate (%) was determined by the following method.

(1) pH buffering capacity (μeq / g) About 0.4 g of sufficiently dried test fiber was precisely weighed (Xg), and 200 ml of water was added thereto. A 1N aqueous solution of caustic soda was added dropwise, and the consumed amount (Ycc) of the aqueous hydrochloric acid solution or aqueous caustic soda solution consumed until the pH reached 5.0 in the case of aqueous hydrochloric acid solution and to reach the level of 7.0 in the case of aqueous caustic soda solution was determined.
The buffer capacity for acid or alkali was calculated by the following equation.

(2) Total carboxyl group content (meq /
g) About 1 g of sufficiently dried test fiber is precisely weighed (Xg), 200 ml of a 1N hydrochloric acid aqueous solution is added thereto, and the mixture is allowed to stand for 30 minutes. Then, the mixture is filtered with a glass filter, water is added, and the mixture is washed with water. After repeating the hydrochloric acid treatment three times, the filtrate is sufficiently washed with water until the pH of the filtrate becomes 5 or more. Next, the sample was put in 200 ml of water, and a 1N hydrochloric acid aqueous solution was added to adjust the pH to 2.
A titration curve was determined with a 0.1N aqueous solution of sodium hydroxide in a conventional manner. From the titration curve, the consumption amount (Ycc) of the aqueous solution of caustic soda consumed by the carboxyl group was determined, and the amount of the carboxyl group was calculated by the following equation.

(3) Metal salt type carboxyl group content (meq
/ G) A sufficiently dried test fiber is precisely weighed, acid-decomposed with a mixed solution of concentrated sulfuric acid and concentrated nitric acid according to a conventional method, and the metal is quantified by an atomic absorption spectrophotometry according to a conventional method, and the amount of carboxyl group bound to the metal is determined. It was calculated as

(4) H-type carboxyl group (meq /
g) The amount of H-type carboxyl group was calculated by the following equation. H-type carboxyl group amount = total carboxyl group amount-metal salt type carboxyl group amount

(5) LOI The measurement was carried out according to the method for measuring the lowest oxygen index of JIS-7201.

(6) Moisture absorption (%) Approximately 5.0 g of sample fiber. Is dried with a hot air dryer at 105 ° C. for 16 hours and weighed (W1 g). Next, the sample was placed in a thermo-hygrostat adjusted to a temperature of 20 ° C. and a relative humidity of 65% for 24 hours.
Put time. The weight of the sample thus absorbed is measured. (W2g). From the above results, calculation was made as follows.

(7) Antibacterial activity The test bacterium was Klebsiella pneumoniae, and was tested by the manual shake evaluation method for the antibacterial and deodorant processed products by the shake flask method (Textile Sanitation Processing Council, 1988) and expressed as a percentage of sterilization rate. Was.

Example 1 90% AN and methyl acrylate (hereinafter referred to as MA)
A spinning stock solution obtained by dissolving 10 parts of an AN polymer (intrinsic viscosity [η] in dimethylformamide at 30 ° C .: 1.2) of 10% in 90 parts of a 48% aqueous solution of rhoda soda is spun and drawn according to a conventional method. After a total draw ratio of 10 times), the material was dried (process shrinkage: 14%) in an atmosphere of dry bulb / wet bulb = 120 ° C./60° C. to obtain a single fiber fineness of 1.5 d (CR).
A dichroic ratio of 0.58) was obtained.

10 g of the raw material fiber was added to 1 L under the conditions shown in Table 1.
Hydrazine aqueous solution and 1 L of NaOH aqueous solution, and then washed with water. One liter of a 1N aqueous hydrochloric acid solution was added to the obtained fiber, left for 30 minutes, filtered through a glass filter, water was added, and the fiber was washed with water. After repeating this acid treatment three times, the filtrate was washed with water until the pH of the filtrate became 5 or more, to obtain a fiber in which the total amount of carboxyl groups became H-type. Next, the obtained fibers were adjusted to the pH shown in Table 1 by adding various metal hydroxides under the conditions shown in Table 1 and left for 30 minutes. Subsequently, after thoroughly washing with water, the fiber was dried. 1-14 were obtained. The characteristic values of the obtained fibers were tested and are shown in Table 2.

[0032]

[Table 1]

[0033]

[Table 2]

The fiber No. of the present invention Nos. 1 to 7 are fibers having high flame retardancy, antibacterial properties, moisture absorption / release properties, and excellent fiber physical properties and high pH buffering ability. Note that this level of antibacterial activity is recognized as having practically sufficient antibacterial activity. On the other hand, the comparative fiber No. 1 having a small increase in nitrogen due to the hydrazine treatment. No. 8 has high hygroscopicity and a large pH buffering property, but has no antibacterial property and a tensile strength of 0.3.
It was as low as 4 g / d, and was a brittle fiber that did not have physical properties to withstand processing such as carding. Comparative Example Fiber No. with a large increase in nitrogen No. 9 had not only low pH buffering capacity but also poor hygroscopicity.

Comparative fiber N in which the ratio of the amount of metal salt type carboxyl groups to the amount of H type carboxyl groups exceeded 4.0 to 1.0.
o. No. 10 was excellent in buffering property against acid but low in buffering property against alkali. Further, the ratio of the amount of metal salt type carboxyl groups to the amount of H type carboxyl groups is 1.0%.
Comparative Example Fiber No. less than 1.5 No. 11 was excellent in buffering property against alkali but low in buffering property against acid.

Comparative Example Fiber No. 1 in which the metal salt type of the carboxyl group was Na or K Samples Nos. 12 to 14 were excellent in buffering property against acid but did not have any buffering property against alkali.

Example 2 Fiber No. 1 of the present invention About JIS-L-0217
According to No. 103, washing was repeated 10 times using weak beads (New Kao Corporation) and neutral Monogen Uni (Daiichi Kogyo Seiyaku Co., Ltd.) as detergents. As a result of measuring the pH buffering capacity of the obtained fiber, those using a weak alkaline detergent showed
50 μeq / g, 190 μeq / g for alkali, and 630 μeq for acid using neutral detergent
eq / g, and 310 μeq / g with respect to alkali. In each case, the washing durability was good, and alkalizing with a detergent did not occur to the extent that the practicality was impaired.

[0038]

With the advent of the present invention, a pH-buffering fiber which has practically no problem in physical properties of a fiber and has flame retardancy, antibacterial properties, and moisture absorption / desorption properties, and to produce the fiber industrially advantageously. The point at which the means can be provided is a remarkable effect of the present invention. The pH buffering fiber of the present invention is itself weakly acidic, and has excellent ability to maintain the pH within the range of 5 to 7 even when attacked by an acid or alkali from the outside. More specifically, LO
It shows flame retardancy of 24 or more by I display, antibacterial property has a sterilization rate of 27% or more by shake flask method, and has a moisture absorption rate of 20% or more. . Furthermore, since it has a strength of 1 g / d or more that can be processed into various forms such as nonwoven fabric, knitted fabric, and woven fabric,
It is widely used in the field of clothing and other fields of application that require other properties such as pH buffering properties.

Claims (2)

(57) [Claims] 1. A crosslinked acrylic fiber wherein the increase in nitrogen content due to hydrazine crosslinking is 1.0 to 8.0% by weight, and 2.5 to 4.5 meq is contained in one part of the residual nitrile group.
/ G of a carboxyl group and the remainder an amide group, and the carboxyl group has C
a, one or two or more metals selected from a, Mg, and Al are combined with H, and the equivalent ratio (metal to H) is in the range of 1.0: 1.5 to 4.0: 1.0. PH-buffering fiber, characterized in that: 2. An increase in nitrogen content of the acrylic fiber by 1.0 to 8.0 by introducing a crosslink through hydrazine treatment.
% By weight, and an amide group is introduced to the remaining carboxyl group in the amount of 2.5 to 4.5 meq / g of the remaining nitrile group by the hydrolysis reaction. At the time of alkaline hydrolysis, after the carboxyl group is converted to H-type by an acid, Ca, Mg,
Manufacture of a pH buffering fiber characterized in that one or more metal hydroxides selected from Al are added to adjust the pH to 5.0 to 7.0 and a part is converted to a metal salt type. Method.