JP3196577B2 - pH buffering hygroscopic acrylic 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.
Has a function of maintaining the pH at a weak acidity of 5 to 7 (hereinafter, simply referred to as weak acidity), and 15 to 35 at 20 ° C. and 65% RH.
The present invention relates to a pH buffering hygroscopic acrylic fiber having a% moisture absorption 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 also has a hygroscopic property and a difficulty that have recently been increasing as social needs. It did not meet the requirements for flammability, antibacterial, antistatic and anti-pill properties.

[0003]

SUMMARY OF THE INVENTION The inventor of the present invention has proposed in order to solve such problems of the prior art.
In step 597, the acrylic fiber is cross-linked by hydrazine treatment, and then subjected to hydrolysis treatment. The generated carboxyl group is converted to an acid form, and a part of the carboxyl group is converted to a metal salt form with a metal hydroxide. A pH buffering fiber and a method for producing the same have been proposed.However, when the carboxyl group is in an acid form, the swelling of the fiber is small and it is difficult to uniformly react to the inside when converting to a metal salt form. It needs to be added in small amounts, it takes a lot of time in industrial production, and a large amount of metal salt is distributed on the surface layer. It has been found that there is a defect in durability such as metal salt falling off, staining of the liquor being contaminated and dyeing and adhering to the product in powder form in the dyeing with a high pH of the solution.

[0004] The present invention has been made in view of the current state of the prior art, and it is an object of the present invention to provide a highly acidic pH buffer having a large durability, a temperature of 20 ° C and 65%.
Has a moisture absorption of 15-35% under RH, and furthermore flame retardant,
An object of the present invention is to provide a pH buffering hygroscopic acrylic fiber having multiple functions of antibacterial, antistatic and anti-pill properties, and an industrially advantageous production method thereof.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, completed the present invention. That is, the present invention relates to a crosslinked acrylic fiber in which an increase in nitrogen content due to hydrazine crosslinking is 1.0 to 8.0% by weight, and a part of the residual nitrile group has a content of 2.5 to 4.5 m.
eq / g of a carboxyl group and the remainder an amide group, and a part of the carboxyl group has a pH of 4.0 to 4.0.
7.0, 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 an equivalent ratio thereof ( PH-buffering hygroscopic acrylic fiber, wherein the metal pair H) is in the range of 1.0 to 1.5 to 4.0 to 1.0. Further, the present invention introduces a crosslinking bond to the acrylic fiber by hydrazine treatment to reduce the nitrogen content by 1.0%.
To 8.0% by weight, and the amount of the nitrile group remaining by the hydrolysis reaction is 2.5 to 4.5 meq / g.
A carboxyl group into the residue and an amide group into the remainder, and in the case of acid hydrolysis, one or two selected from Li, Na and K
In the case of alkali hydrolysis, at least one kind of hydroxide is adjusted to pH 4.0 to 7.0 with one or more kinds of acids selected from sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid to adjust the carboxyl group. After converting the part into salt form, Ca, Mg,
1 selected from nitrate, hydrochloride, sulfate and phosphate of Al
A method for producing a pH-buffering hygroscopic acrylic fiber, comprising adding a seed or two or more metal salts to convert a part into a metal salt type.

Hereinafter, the present invention will be described in detail. First, the crosslinked acrylic fiber of the present invention is a fiber formed of an AN polymer containing acrylonitrile (hereinafter referred to as AN) as a starting acrylic fiber in an amount of 40% by weight or more, preferably 50% by weight or more, It may be in any form such as short fiber, tow, thread, knitted fabric, non-woven fabric and the like, or may be in the middle of the manufacturing process, waste fiber, or the like. 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 limited to 1.0 to 8.0.
The concentration is not particularly limited as long as the means can be adjusted to the 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%).
(C) for 1 to 8 hours (preferably 1 to 4 hours). 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 above lower limit, fibers having physical properties satisfactory for practical use cannot be finally obtained, and furthermore, flame retardancy, antibacterial property, antistatic property, If the pill properties are not multifunctional, and if the upper limit is exceeded, the hygroscopicity and the pH buffering property cannot be obtained, and none of the objects of the invention can be achieved. Examples of the hydrazine that can be employed here include hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, hydrazine nitrate, and hydrazine bromate.

In addition, a nitrile group remaining without hydrazine crosslinking is substantially eliminated by a 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, when the amount of carboxyl groups is less than the above lower limit, a practically satisfactory pH buffering capacity cannot be obtained, and furthermore, 20 ° C. and 65% R
Under H, a moisture absorption of 15 to 40% cannot be obtained, and furthermore, multifunctionality such as flame retardancy, antibacterial property, antistatic property and anti-pill property 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 two 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, One or two or more hydroxides selected from Li, Na, and K. In the case of alkali hydrolysis, one or two or more acids selected from sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid are used. One or two or more metals selected from Ca, Mg, Al nitrates, hydrochlorides, and phosphates as essential components by adjusting a part of the carboxyl group to a salt form by adjusting to 0 to 7.0. A method of converting a part of the carboxyl group into a metal salt by adding a salt, followed by washing with water, treatment with an oil agent, and drying is used. The hydroxides, mineral acids and metal salts used here have a high solubility in water and pH
Is adjusted to 4.0 to 7.0, a part of the carboxyl group becomes dissociated, the microstructure of the fiber thus treated is semi-swelled, and the conversion to the metal salt is uniformly and even to the inside of the fiber. Done quickly. This method makes it possible to industrially produce a pH-buffering hygroscopic fiber for the first time in an industrially advantageous manner, and can prevent the metal salt from falling off during dyeing and washing.

It is not recommended to use a metal salt type carboxyl group other than Ca, Mg and Al because the pH cannot be buffered to a weakly acidic one or there is a risk of harm to the human body. For example, alkali metal salts such as Na, K, and Li have a pH buffering capacity for acids, but are inferior in buffering capacity for alkalis. If the H-type ratio is increased in order to avoid this, the buffering capacity against acid decreases, and p having substantially weakly acidic buffering capacity is obtained.
No longer H buffered fiber. Next, the ratio of the Ca, Mg, Al metal salt type carboxyl groups to the H type carboxyl groups is 1.0
When the ratio is less than 1.5, the buffering property against acid is small. When the ratio exceeds 4.0 to 1.0, the buffering property against alkali is low and the pH-buffering fiber has a weak acidity in practical use. None of them can achieve the object of the invention. In the present invention, Ca, Mg,
It is essential that either of Al is adopted,
Buffer, flame retardant, antibacterial, antistatic, anti-pill and 20 ° C
Other metals can be used within a range that does not impair the moisture absorption of 15 to 35% under 65% RH. However, its content is 0.4 me as a metal salt type carboxyl group.
q / g or less.

In this manner, flame retardant, antibacterial, antistatic, anti-pill, and pH-buffer-resistant at a tensile strength of 1 g / d or more and a moisture absorption of 15 to 35% at 20 ° C. and 65% RH. Acrylic fiber having both of the above can be industrially advantageously provided. The thus produced fiber of the present invention can be referred to as an acryl-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 a starting acrylic fiber as described later.

As an apparatus for producing the above-mentioned acrylic fiber, an acrylic fiber is filled in a container provided with a pump circulation system, and the above-mentioned respective reactions of introduction of cross-linking, hydrolysis, and formation of a metal salt are performed. Is desirable in terms of safety, uniform reactivity, and the like. As a typical example of such a device (a container provided with a pump circulation system), a pressurized Overmeyer dyeing machine and the like can be mentioned.

In addition, fiber properties and pH buffering properties, flame retardancy, antibacterial properties, anti-pill properties, antistatic properties and 20 ° C.
In order to provide a fiber having a moisture absorption of 15 to 35% under 5% RH, it is particularly preferable to use a starting acrylic fiber having the following characteristics.

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 advantageously by adopting a means that 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 before drawing and before heat treatment (a 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, especially wet or dry / wet spinning, and water-swelled gel fibers after stretching: the degree of water swelling is 30 to 150%), dispersibility of the fibers in the reaction solution, This is desirable because the permeability of the reaction solution into the solution is improved, and the introduction of the cross-linking and the hydrolysis reaction can be performed uniformly and promptly. The degree of water swelling is a percentage of the water content expressed on a dry fiber weight basis.

[0018]

According to the present invention, the pH-buffering hygroscopic acrylic fiber and the method for producing the same have flame retardancy, antibacterial property, anti-pill property, antistatic property and a moisture absorption of 15 to 35% at 20 ° C. and 65% RH. The reasons for the combination have not been fully elucidated, but are generally considered as follows.

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

In general, salt-type carboxyl groups have a pH buffering property. However, in the present invention, a specific ratio of a carboxyl group of a metal salt form of Ca, Mg, or Al to H-form is weakly acidic and exhibits a buffering property. This is probably because the base metal salt and the weak acid coexist appropriately. It is presumed that the flame retardancy is provided by the crosslinked structure and the metal salt of acrylamide and carboxylic acid, and the antibacterial property is provided by the crosslinked structure. The antistatic property may be due to the leakage effect due to high moisture absorption, the anti-pill property may be due to low strength, and the high moisture absorption may be due to the crosslinked structure and the metal salt type carboxyl group. Further, the processing performance is likely to be largely attributable to the intramolecular and intermolecular ionic cross-linking caused by the polyvalent metal and the orientation structure observed in the CR dichroic ratio.

[0021]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited thereto. Parts and percentages in the examples are on a weight basis 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, antibacterial properties ( Difference in increase or decrease), anti-pill property (ICI
Grade) and antistatic property (half-life) were determined by the following methods.

(1) pH buffering capacity (μeq / g) About 0.4 g of sufficiently dried test fiber was precisely weighed (X) g, and 200 ml of water was added thereto. A 1N aqueous solution of caustic soda was added dropwise, and the consumed amount (Y) cc of the aqueous hydrochloric acid solution or aqueous caustic soda solution consumed until the pH reached 5.0 in the case of an aqueous hydrochloric acid solution and to 7.0 in the case of an 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) Approximately 1 g of sufficiently dried test fiber is precisely weighed (X) g, and 200 ml of a 1N hydrochloric acid aqueous solution is added thereto. The mixture is left for 30 minutes, filtered through a glass filter, added with water, and 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 (Y) cc of the aqueous solution of caustic soda consumed by the carboxyl groups was determined, and the total carboxyl group amount was calculated by the following equation.

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

(4) H-type carboxyl group content (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 (%) About 5.0 g of the sample fiber is dried with a hot air drier at 105 ° C. for 16 hours, and the weight (W1) g is measured. Next, the sample was heated to temperature 2
It is placed in a thermo-hygrostat adjusted to a relative humidity of 65% at 0 ° C. for 24 hours. The weight of the sample thus absorbed (W
2) Measure g. From the above results, the moisture absorption was calculated according to the following equation.

(7) Antibacterial test strain: Stapylococcus aureus I
FO 12732 Test method: According to the method specified by the Textile Sanitary Processing Council (SEK), pour a bouillon suspension of the test bacterium on a sterile sample cloth, and culture in a closed container at 37 ° C for 18 hours. The number of cells is measured, and the difference between the number of bacteria B of the standard cloth and the number of bacteria C of the sample with respect to the number A of inoculated bacteria is determined. Increase / decrease value = logC-logA Increase / decrease value difference = (logB−logA) − (logC−log
gA)

(8) Anti-pill property A pilling test method for JIS L 1076 woven and knitted fabrics was carried out according to a method A using an ICI type testing machine.

(9) Antistatic property The antistatic property was measured in accordance with JIS L 1094.

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 performing a total stretching ratio of 10 times), the film was dried in an atmosphere of dry bulb / wet bulb = 120 ° C./60° C., and then subjected to relaxation treatment (process shrinkage 27%) under a high-pressure steam at 125 ° C. Raw fiber (CR dichroism ratio: 0.56) having a single fiber fineness of 1.0 d was obtained.

[0033] 10 g of the raw 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. The obtained fiber was subjected to a pH adjustment treatment under the conditions described in Table 1 and then washed with water to partially remove carboxyl groups.
A shaped fiber was obtained. The amount of increase in nitrogen after the hydrazine treatment was 5.0% by weight, and the total carboxyl amount after the hydrolysis treatment was 4.2 meq / g. Next, the obtained fiber was treated with a metal salt by adding various metal salts under the conditions shown in Table 1. After washing thoroughly with water and drying, pH buffering hygroscopic fiber N
o. 1 to 7 were obtained. This No. Table 2 shows the characteristic values of the pH buffering hygroscopic fibers of 1 to 7.

[0034]

[Table 1]

[0035]

[Table 2]

As can be seen from Tables 1 and 2, the pH buffering hygroscopic fiber No. 1 of the present invention example. Nos. 1 to 5 are comparative examples No. 1 proposed by the present inventors. Despite significantly shortening the pH adjustment and metal salt treatment time as compared with 6 to 7, excellent performance is obtained that is not inferior to any of the characteristic values of tensile strength, flame retardancy, antibacterial properties, and moisture absorption. be able to.

Example 2 Examples of the present invention (fibers No. 1 and No. 1) prepared in Example 1.
The three types of pH buffering hygroscopic fibers of 4) and 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 cottons are subjected to blending, carding, drawing, roving and spinning according to a conventional method, and
A yarn having a / 52 meter count and a twist number of 830 T / M was produced. Next, these yarns were knitted with a 20-gage smooth knitting machine to prepare knitted fabric samples A to F shown in Table 3 having a basis weight of 200 ± 20 g / m ² . 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 present invention examples (fiber No. 1 and No. 4)
There was no problem in processing in any of the spinning, knitting, and dyeing processes. However, in the comparative example (fiber No. 6), white powder was observed in the carding process and the spinning process, and the bleached dyeing residual bath A lot of turbidity was observed. This is presumably because unreacted calcium hydroxide remained on the fiber surface and inside the fiber irrespective of the time taken for pH adjustment and metal hydroxide treatment.

The moisture absorption of the sample knitted fabrics AF after bleach dyeing,
Table 4 shows the results of the antibacterial, antistatic, and anti-pill tests. It can be seen that the sample knitted fabrics A and B of the present invention all show excellent characteristics, and that the sample knitted fabrics C to D mixed with 30% show sufficient characteristics for practical use. This is because the metal salt treatment adjusts the pH to 4.0 to 7.0 to convert a part of the carboxyl groups into a salt form, and then the metal salt treatment uniformly reacts to the inside of the fiber and significantly improves the durability. Probably because
The sample knitted fabrics EF of the comparative example also maintain the practical performance targeted by the inventor, but have a problem in that there are restrictions on the processing surface.

[0041]

[Table 4]

[0042]

Industrial Applicability According to the present invention, fiber properties which are practically no problem are maintained, and the saturated moisture absorption at 20 ° C. × 65 RH is 15%.
It is an object of the present invention to provide a pH-buffering hygroscopic acrylic fiber having about 35% and having flame retardancy, antibacterial property, antistatic property and anti-pill property, and a means for industrially advantageously producing the fiber. it can. The pH buffering hygroscopic acrylic 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, it shows flame retardancy of 24 or more in LOI display,
The antibacterial activity exceeds the standard value of 1.6 due to the difference in the increase or decrease in the number of SEK bacteria.
Conventional synthetic fibers have anti-pill properties of more than 3 grades in a 30% blend knitted fabric according to the ICI method, and antistatic properties have a half life of less than 15 seconds in a 30% blended knitted fabric at 20 ° C x 40 RH. Has remarkable properties compared to natural fibers. Furthermore, because it can be processed into various forms such as non-woven fabric, knitted fabric, and woven fabric,
It is widely used in various fields such as clothing, living materials and industrial materials.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-41871 (JP, A) JP-A-6-41870 (JP, A) JP-A 4-185764 (JP, A) JP-A-2- 84528 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) D06M 11/00-15/715

Claims (2)

(57) [Claims] 1. A crosslinked acrylic fiber in which an increase in nitrogen content by hydrazine crosslinking is 1.0 to 8.0% by weight, and 2.5 to 4.5 meq is contained in a part of the residual nitrile group.
/ G of a carboxyl group and an amide group in the rest, and a part of the carboxyl group has a pH of 4.0 to 7.0.
, Ca, Mg, Al nitrates, hydrochlorides, sulfates,
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 in the range of 2.0. 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, a carboxyl group is introduced into the remaining amount of the nitrile group by the hydrolysis reaction in an amount of 2.5 to 4.5 meq / g, and an amide group is introduced into the remainder. One or more hydroxides selected from Li, Na, and K. In the case of alkaline hydrolysis, sulfuric acid, hydrochloric acid,
P with one or more acids selected from nitric acid and phosphoric acid
After adjusting the H to 4.0 to 7.0 to convert 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, comprising adding two or more metal salts to convert a part into a metal salt type.