JPH08325938A - pH buffer hygroscopic acrylic fiber and method for producing the same - Google Patents

Abstract

(57) [Abstract] [Purpose] It has a weak acidic pH buffering capacity, is durable, and has a moisture absorption rate of 15 to 35% at 20 ° C. and 65% RH. Provided is a pH-buffering hygroscopic acrylic fiber having multifunctional antistatic and anti-pill properties. A crosslinked acrylic fiber having an increase in nitrogen content of 1.0 to 8.0% by weight due to hydrazine crosslinking, in which 2.5 to 4.5 meq /
g of the carboxyl group and the rest of which is an amide group, and part of the carboxyl group is selected from nitrates, hydrochlorides, sulfates and phosphates of Ca, Mg and Al at pH 4.0 to 7.0. And a metal salt type obtained by adding one or more metal salts obtained by conversion, and an equivalent ratio thereof (metal to H)
Is in the range of 1.0 to 1.5 to 4.0 to 1.0, and is a pH buffering hygroscopic acrylic fiber.

Description

Detailed Description of the Invention

[0001]

This invention relates to the pH of water contacting fibers.
Having a pH of 5 to 7 (hereinafter referred to as "weak acid") has a function of maintaining pH of 5 to 7, and at 15 to 35 at 20 ° C and 65% RH.
The present invention relates to a pH buffering hygroscopic acrylic fiber having a hygroscopicity of 10% and a method for producing the same.

[0002]

2. Description of the Related Art Under normal conditions, human skin is kept weakly acidic by secreted lactic acid and the like, but the pH of the skin is maintained by acid rain due to recent environmental damage and alkalinization of clothes by washing. Beyond the normal range, this compromises healthy skin. In order to keep the skin pH weakly acidic, it is desirable that the external acid or alkali be neutralized by clothes and that the fiber material itself that comes into contact with the skin be weakly acidic. As a method of responding to such a demand, there is a method in which a protein having a weakly acidic isoelectric point is attached to a textile product by post-processing. However, this method has a drawback in that it cannot be easily processed into various forms because the pH buffer substance is attached to the textile product by post-processing, and the hygroscopic property and difficulty which are recently increasing as social needs. It did not meet the requirements for flammability, antibacterial properties, antistatic properties, and antipill properties.

[0003]

DISCLOSURE OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present inventor has filed Japanese Patent Application No. 6-36.
In 597, the acrylic fiber is crosslinked by hydrazine treatment, and then subjected to hydrolysis treatment to convert the produced carboxyl group into an acid form, and then partially convert it into a metal salt form with a metal hydroxide. We proposed a pH buffering fiber and its manufacturing method. However, when the carboxyl group is an acid type, the amount of metal hydroxide added is small because the swelling of the fiber is small and it is difficult to react uniformly to the inside when converting to a metal salt type. It is necessary to add it in small amounts, it takes a lot of time for industrial production, and since a large amount of metal salt is distributed in the surface layer part, especially when dyeing the pH buffer fiber produced by that method, It has been revealed that there is a defect in durability, such as metal salts falling off in dyeing with a high liquid pH, the dyeing liquid is contaminated and dyed and adheres to the product in powder form.

The present invention was devised in view of the current state of the art, and an object of the present invention is to have a weak acidic pH buffering capacity, durability, and 20 ° C. 65%.
It has a moisture absorption rate of 15-35% under RH, and is also flame retardant,
It is an object of the present invention to provide a pH-buffering hygroscopic acrylic fiber having multiple functions of antibacterial property, antistatic property, and anti-pill property, and an industrially advantageous production method thereof.

[0005]

The inventor of the present invention has made extensive studies to achieve the above object, and as a result, the present invention has been completed. That is, the present invention is a crosslinked acrylic fiber having an increase in nitrogen content of 1.0 to 8.0% by weight due to hydrazine crosslinking, and 2.5 to 4.5 m in a part of residual nitrile groups.
The carboxyl group of eq / g and the amide group are introduced in the balance, and a part of the carboxyl group has a pH of 4.0 to 4.0.
At 7.0, it is a metal salt type converted by adding one or more metal salts selected from nitrates, hydrochlorides, sulfates and phosphates of Ca, Mg and Al, and its equivalent ratio ( A pH buffering hygroscopic acrylic fiber characterized in that the metal pair H) is in the range of 1.0: 1.5 to 4.0: 1.0. In addition, the present invention introduces a cross-linking bond into acrylic fiber by hydrazine treatment to increase the nitrogen content by 1.0.
Adjusted to within a range of from 8.0 to 8.0% by weight, and 2.5 to 4.5 meq / g of the amount of the nitrile group remaining by the hydrolysis reaction.
In the case of acid hydrolysis by introducing a carboxyl group into and a amide group into the balance, one or two selected from Li, Na, and K are used in the case of acid hydrolysis.
In the case of alkali hydrolysis, one or more kinds of hydroxides are used to adjust the pH to 4.0 to 7.0 with one or more kinds of acids selected from sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, and one of the carboxyl groups is After making the part salt type, Ca, Mg, as essential components,
1 selected from Al nitrate, hydrochloride, sulfate and phosphate
A method for producing a pH-buffering hygroscopic acrylic fiber, which comprises adding one kind or two or more kinds of metal salts and converting a part thereof into a metal salt type.

The present invention will be described in detail below. First, the crosslinked acrylic fiber of the present invention is a fiber formed from an AN polymer containing 40% by weight or more, preferably 50% by weight or more of acrylonitrile (hereinafter referred to as AN) as the starting acrylic fiber, It may be in any form such as short fibers, tows, yarns, knitted fabrics, non-woven fabrics, etc., and may be intermediate products in the manufacturing process, waste fibers, 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; methallyl sulfone. Acids, sulfonic acid-containing monomers such as p-styrenesulfonic acid and salts thereof; carboxylic acid group-containing monomers such as (meth) acrylic acid and itaconic acid and salts thereof; other monomers such as acrylamide, styrene and vinyl acetate. .

As a method of introducing hydrazine crosslinks into the acrylic fiber, the nitrogen content is increased by 1.0 to 8.0.
There is no particular limitation as long as it is a means capable of adjusting the concentration to 5% by weight, but the concentration is 5 to 80% by weight (preferably 5 to 40% by weight), and the temperature is 50 to 130 ° C (preferably 85 to 130%).
Means for treating at 1 ° C.) for 1 to 8 hours (preferably 1 to 4 hours) is industrially preferable. Here, the increase of the nitrogen content means the difference between the nitrogen content of the raw material acrylic fiber and the nitrogen content of the hydrazine-crosslinked acrylic fiber.

When the increase in nitrogen content is less than the above lower limit, finally, fibers having physical properties that are practically satisfactory cannot be obtained, and in addition flame retardancy, antibacterial property, antistatic property, If the pill-like multi-function is not obtained, and if it exceeds the upper limit, neither hygroscopicity nor pH buffering is obtained, and neither of the objects of the invention is achieved. Examples of hydrazine that can be used here include hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, hydrazine nitrate, and hydrazine bromate.

Further, the hydrolysis reaction substantially eliminates the nitrile group remaining without being crosslinked with hydrazine, and finally introduces 2.5 to 4.5 meq / g of the carboxyl group and the amide group in the balance. Examples of the method include a method of impregnating an alkaline metal hydroxide, a basic aqueous solution of ammonia or the like, or an aqueous solution of a mineral acid such as nitric acid, sulfuric acid or hydrochloric acid, or a method of heat-treating the raw material fibers in a state of being immersed in the aqueous solution. Can be mentioned. The hydrolysis reaction can be carried out simultaneously with the introduction of the cross-linking bond. Here, when the amount of carboxyl groups is finally less than the above lower limit, practically satisfactory pH buffering ability cannot be obtained, and further, 20 ° C. 65% R
A moisture absorption rate of 15 to 40% is not obtained under H, and besides, multi-functionality of flame retardancy, antibacterial property, antistatic property, and antipill property cannot be obtained.
On the other hand, if the upper limit is exceeded, a fiber having physical properties that are practically satisfactory cannot be obtained.

The carboxyl group thus introduced is one or two selected from Ca, Mg and Al as an essential component.
As a method of adjusting the equivalent ratio of at least one kind of metal and H (metal to H) from 1.0: 1.5 to 4.0: 1.0, when the above-mentioned hydrolysis is carried out with an acid, One or two or more hydroxides selected from Li, Na and K, and at the time of alkali hydrolysis, one or two or more acids selected from sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid to give a pH of 4. It is adjusted to 0 to 7.0 to convert a part of the carboxyl group into a salt form, and one or more metals selected from nitrates, hydrochlorides and phosphates of Ca, Mg and Al as essential components. A method of adding a salt to convert a part of the carboxyl group into a metal salt, and then washing with water, treating with an oil agent, and drying is used. The hydroxides, mineral acids and metal salts used here have high solubility in water and pH
By adjusting the ratio to 4.0 to 7.0, a part of the carboxyl groups is in a dissociated state, the fine structure of the fiber thus treated is semi-swelled, and the conversion into the metal salt is even inside the fiber. It is done quickly. Only by this method can the pH buffer hygroscopic fiber be industrially produced advantageously, and it is possible to prevent the metal salt from falling off during dyeing and washing.

It should be noted that metal salt type carboxyl groups other than Ca, Mg and Al cannot be recommended because they cannot buffer the pH in a weakly acidic manner or are harmful to the human body. For example, alkali metal salt types such as Na, K, and Li have a pH buffering capacity for acids, but have a poor buffering capacity for alkalis. To avoid this, if the H-type ratio is increased, the buffering property against acid is lowered, and the p-
It is no longer a H-buffering fiber. Next, the ratio of Ca, Mg, and Al metal salt type carboxyl groups to H type carboxyl groups is 1.0.
If the ratio is less than 1.5, the acid buffering property is low, and if it exceeds 4.0 to 1.0, the alkali buffering property is low and the pH buffering fiber has a weak acidic buffering capacity in practice. However, neither of them can achieve the object of the invention. In the present invention, the types of metal salts are Ca, Mg,
It is essential that either Al is adopted, but the pH
Buffer, flame retardant, antibacterial, antistatic, anti-pill and 20 ℃
It is also possible to use a metal other than these within a range that does not impair the moisture absorption rate of 15 to 35% under 65% RH. However, its content is 0.4 me as a metal salt type carboxyl group.
It is q / g or less.

In this way, a flame retardant, antibacterial, antistatic, anti-pill property having a pH buffering property at a tensile strength of 1 g / d or more and a moisture absorption rate of 15 to 35% at 20 ° C. and 65% RH. It is possible to industrially provide an acrylic fiber having the above-mentioned advantages. The fiber of the present invention thus produced can be referred to as an acrylic modified fiber because the nitrile group is largely modified. 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.

As a device for producing the acrylic fiber, the acrylic fiber is filled in a container equipped with a pump circulation system, and each reaction of introducing the above-mentioned cross-linking, hydrolyzing reaction, and forming a metal salt is carried out. A means for sequentially performing is preferable from various points such as safety and uniform reactivity. As a typical example of such an apparatus (container equipped with a pump circulation system), a pressure type Overmeier dyeing machine and the like can be mentioned.

Further, there are practically no problems in physical properties of fibers, pH buffering property, flame retardancy, antibacterial property, antipill property, antistatic property and 20 ° C. 6
In order to provide a fiber having a moisture absorption rate of 15 to 35% under 5% RH, it is particularly preferable to employ a starting acrylic fiber having the following characteristics.

That is, the AN-based 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 dichroic ratio is calculated by Polymer Chemistry 23 (252) 193 (196).
6) It is obtained according to the method described.

There is no limitation on the means for producing the acrylic fiber, 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 4 times or more, preferably. The desired acrylic fiber can be industrially advantageously produced by adopting a means in which the process shrinkage is 8 times or more and the process shrinkage is 40% or less, preferably 30% or less.

Further, as a starting acrylic fiber, a fiber after drawing and before heat treatment (a spinning dope of an AN polymer is spun according to a conventional method and stretched and oriented, but it is subjected to heat treatment such as dry densification and heat and heat relaxation treatment). Dispersion of the fiber in the reaction solution, in the fiber by using non-treated fiber, especially wet or dry / wet spinning, water-swelling gel fiber after stretching: water swelling degree is 30 to 150%) It is desirable that the permeability of the reaction solution into the reaction solution is improved and the introduction of cross-linking and the hydrolysis reaction are carried out uniformly and rapidly. The degree of water swelling is the percentage of the water content expressed on the basis of dry fiber weight.

[0018]

The pH buffering hygroscopic acrylic fiber and the method for producing the same according to the present invention have flame retardancy, antibacterial properties, anti-pill properties, antistatic properties, and a hygroscopicity of 15 to 35% at 20 ° C. and 65% RH. The reason for having both has not been fully clarified, but it can be considered as follows.

That is, since the fiber according to the present invention starts from an AN-based polymer, the nitrile group is substantially eliminated, so that the side chain bonded to the polymer chain reacts with hydrazine. A nitrogen-containing crosslinked structure produced by H and H-type produced by the hydrolysis reaction of a nitrile group,
It is considered to be a metal salt type carboxyl group and an amide group.

Generally, a salt type carboxyl group has a pH buffering property, but in the present invention, it is weak that a specific ratio of the Ca, Mg, Al metal salt type and H type carboxyl groups has a weakly acidic buffering property. This is probably because the metal salt of the base and the weak acid coexist appropriately. It is presumed that the flame retardancy is caused by the crosslinked structure and the metal salts of acrylamide and carboxylic acid, and the antibacterial property is brought by the crosslinked structure. Further, the antistatic property may be due to the leakage effect due to the high moisture absorption, the anti-pill property may be due to the low strength, and the higher moisture absorption may be due to the crosslinked structure and the metal salt type carboxyl group. Further, the processing performance is largely supported by the intramolecular and intermolecular ionic crosslinks due to the orientational structure and polyvalent metal seen in the CR dichroic ratio.

[0021]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. Parts and percentages in the examples are by weight unless otherwise specified.

PH buffering capacity (μeq / g), total carboxyl group amount, metal salt type carboxyl group amount, H type carboxyl group amount (meq / g), LOI (limit oxygen index), moisture absorption rate, antibacterial property ( Increase / decrease difference), anti-pill (ICI
Grade) and antistatic property (half-life) were determined by the following methods.

(1) pH buffering capacity (μeq / g) Approximately 0.4 g of sufficiently dried test fiber was precisely weighed (X) g, and 200 ml of water was added thereto, and then 0.1N hydrochloric acid aqueous solution or 0 was added. Add 1N caustic soda solution dropwise to obtain the consumed hydrochloric acid aqueous solution or caustic soda aqueous solution consumption (Y) cc until the pH reaches 5.0 for the hydrochloric acid aqueous solution and pH 7.0 for the caustic soda aqueous solution. The buffer capacity for acid or alkali was calculated by the following formula.

(2) Total amount of carboxyl groups (meq /
g) About 1 g of sufficiently dried test fiber is precisely weighed (X) g, 200 ml of 1N hydrochloric acid aqueous solution is added thereto, left for 30 minutes, filtered through a glass filter, and water is added to wash. After repeating this hydrochloric acid treatment 3 times, the filtrate is sufficiently washed with water until the pH thereof becomes 5 or more. Next, after putting this sample in 200 ml of water and adding 1N hydrochloric acid aqueous solution to adjust to pH 2,
A titration curve was obtained using a 0.1N-caustic soda aqueous solution according to a conventional method. The caustic soda aqueous solution consumption (Y) cc consumed for the carboxyl groups was obtained from the titration curve, and the total amount of carboxyl groups was calculated by the following formula.

(3) Amount of metal salt type carboxyl group (me
q / g) A sufficiently dried test fiber is precisely weighed and acid-decomposed by a mixed solution of concentrated sulfuric acid and concentrated nitric acid according to a conventional method, and then the metal is quantified by an atomic absorption spectrophotometric method according to a conventional method to determine a carboxyl group to which the metal is bound. Calculated as amount.

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

(5) LOI JIS-7720 was measured according to the method of measuring the lowest oxygen index.

(6) Moisture absorption rate (%) About 5.0 g of sample fiber is dried with a hot air dryer at 105 ° C. for 16 hours, and the weight (W1) g is measured. Then sample 2
It is placed in a thermo-hygrostat adjusted to a relative humidity of 65% at 0 ° C. for 24 hours. The weight (W
2) Measure g. From the above results, the moisture absorption rate was calculated according to the following equation.

(7) Antibacterial test strain: Staphylococcus aureus I
FO 12732 Test method: A broth suspension of the test bacteria was added to a sterilized sample cloth according to the method specified by the Textile Products Sanitary Processing Council (SEK), and the live bacteria after culturing at 37 ° C for 18 hours in a closed container. The number is measured, and it is determined by the difference between the increase and decrease in the number B of bacteria of the standard cloth and the number C of bacteria of the sample with respect to the number A of inoculum. Increase / decrease value = logC-logA Increase / decrease value difference = (logB-logA)-(logC-lo
gA)

(8) Anti-pill property JIS L 1076 Pilling test method for woven and knitted fabrics was carried out according to the method A using the ICI type tester.

(9) Antistatic property JIS L 1094 The antistatic property of the woven and knitted fabrics was tested according to the test method.

Example 1 90% AN and methyl acrylate (hereinafter referred to as MA)
A spinning dope prepared by dissolving 10 parts of a 10% AN polymer (intrinsic viscosity [η]: 1.2 in 30 ° C. dimethylformamide) in 90 parts of a 48% aqueous rhodanesoda solution was spun and stretched according to a conventional method. (Total draw ratio: 10 times), dried in a dry bulb / wet bulb = 120 ° C./60° C. atmosphere, and then subjected to a relaxation treatment (process shrinkage rate 27%) under a high pressure steam of 125 ° C. A raw material fiber (CR dichroic ratio 0.56) having a single fiber fineness of 1.0 d was obtained.

10 g of the raw material fiber is 1 L under the conditions shown in Table 1.
It was washed with water after being treated with the hydrazine aqueous solution and the 1 L NaOH aqueous solution. The obtained fiber was subjected to pH adjustment treatment under the conditions shown in Table 1 and then washed with water so that part of the carboxyl groups was H.
A shaped fiber was obtained. The amount of nitrogen increase after the hydrazine treatment was 5.0% by weight, and the total amount of carboxyl after the hydrolysis treatment was 4.2 meq / g. Next, the obtained fiber was subjected to metal salt treatment by adding various metal salts under the conditions shown in Table 1. After being thoroughly washed with water, dried and pH-buffered hygroscopic fiber N
o. 1 to 7 were obtained. This No. The characteristic values of the pH buffering hygroscopic fibers of 1 to 7 are shown in Table 2.

[0034]

[Table 1]

[0035]

[Table 2]

As can be seen from Table 1 and Table 2, the pH buffering hygroscopic fiber No. 1 of the present invention example. Comparative Examples No. 1 to No. 5 were previously proposed by the present inventor. Despite significantly shortening the pH adjustment and metal salt treatment time compared to 6 to 7, it obtains excellent performance that is not inferior to any of the characteristic values of tensile strength, flame retardancy, antibacterial property, and moisture absorption rate. be able to.

Example 2 An example of the present invention (fiber No. 1 and No. 1) prepared in Example 1.
4) and the three types of pH buffering hygroscopic fibers of Comparative Example (fiber No. 6) were treated with an oil agent and dried to obtain 1.8 denier × 48 mm product raw cotton. These raw cotton products are blended, carded, kneaded, roved, and spun according to a conventional method.
A yarn having a / 52 meter count and a twist number of 830 T / M was prepared. Next, knitted fabric samples A to F shown in Table 3 having a basis weight of 200 ± 20 g / m ² were prepared from these yarns using a 20 gauge smooth knitting machine. Next, these sample knitted fabrics were subjected to bleach dyeing with H ₂ O ₂ / NaOH (pH = 9, 80 ° C. × 60 minutes).

[0038]

[Table 3]

The examples of the present invention (fiber No. 1 and No. 4) are
There were no problems in processing in any of the spinning, knitting, and dyeing processes, but in the comparative example (fiber No. 6), white powder was observed in the carding process and the spinning process, and the bleaching dyeing residual bath A lot of turbidity was observed. It is considered that this is because unreacted calcium hydroxide remained on the fiber surface and inside the fiber, regardless of the time required for pH adjustment and metal hydroxide treatment.

Moisture absorption of the sample knitted fabrics AF after bleaching dyeing,
Table 4 shows the results of the antibacterial, antistatic and antipill test. It is understood that the sample knitted fabrics A to B of the examples of the present invention all exhibit excellent properties, and the sample knitted fabrics C to D containing 30% of each of them show sufficient practical effects. This is because the metal salt treatment adjusts the pH to 4.0-7.0 to make a part of the carboxyl groups into a salt type, and then the metal salt treatment causes a uniform reaction to the inside of the fiber and significantly improves durability. Probably because I did.
The sample knitted fabrics E to F of the comparative example also maintain the practical performance targeted by the present inventor, but there is a problem in that there is a restriction in terms of processing.

[0041]

[Table 4]

[0042]

EFFECTS OF THE INVENTION According to the present invention, the physical properties of fibers which are practically no problem are maintained, and the saturated moisture absorption at 20 ° C. × 65 RH is 15%.
To provide a pH-buffering hygroscopic acrylic fiber having flame retardancy, antibacterial property, antistatic property, and anti-pill property, having a content of ˜35%, and a means for industrially producing the fiber. it can. The pH-buffering hygroscopic acrylic fiber of the present invention itself is 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. Also, specifically, it shows 24 or more flame retardancy in LOI display,
The antibacterial property exceeds the standard value of 1.6 due to the difference in the number of SEK bacteria,
The anti-pill property exceeds Class 3 in the knitted fabric containing 30% by the ICI method, and the antistatic property is less than 15 seconds in the knitted fabric containing 30% with a half-life at 20 ° C × 40RH. It has outstanding performance compared to natural fiber. Furthermore, since it can be processed into various forms such as non-woven fabrics, knitted fabrics, and woven fabrics,
Widely used in various fields of application such as clothing and daily life materials and industrial materials.

Claims (2)

[Claims] 1. A crosslinked acrylic fiber having an increase in nitrogen content of 1.0 to 8.0% by weight due to hydrazine crosslinking, and 2.5 to 4.5 meq in a part of residual nitrile groups.
/ G of carboxyl group and the amide group are introduced in the balance, and a part of the carboxyl group has a pH of 4.0 to 7.0.
In Ca, Mg, Al nitrate, hydrochloride, sulfate,
It is a metal salt type converted by adding one or more metal salts selected from phosphates, and its equivalent ratio (metal to H) is 1.0: 1.5 to 4.0: 1. PH-buffering hygroscopic acrylic fiber characterized by being in the range of 0.0. 2. An increase in nitrogen content of 1.0 to 8.0 by introducing a cross-linkage into acrylic fibers by hydrazine treatment.
The content of the carboxyl group is adjusted to be within the range of 0.5% by weight, a carboxyl group is introduced into 2.5 to 4.5 meq / g of the amount of the nitrile group remaining by the hydrolysis reaction, and an amide group is introduced into the balance. One or two or more hydroxides selected from Li, Na, and K, and when alkaline hydrolysis, sulfuric acid, hydrochloric acid,
P with one or more acids selected from nitric acid and phosphoric acid
After adjusting to H4.0 to 7.0 to make a part of the carboxyl group into a salt form, one or more selected from nitrates, hydrochlorides, sulfates and phosphates of Ca, Mg and Al as essential components or A method for producing a pH-buffering hygroscopic acrylic fiber, which comprises adding two or more metal salts and converting a part thereof into a metal salt type.