JP2002294556A - Hygroscopic synthetic fiber with high whiteness, and method for producing the fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hygroscopic fiber with high whiteness, having basic properties required for the fiber, characteristics to be possessed by the hygroscopic fiber, improved whiteness and excellent color stability hardly causing color change even in a finishing step or when being used as a final product, and further to provide a method for producing the fiber. SOLUTION: This hygroscopic synthetic fiber having >=10 wt.% saturated moisture absorption at 20 deg.C in 65%RH humidity is characterized in that the whiteness of the fiber represented by the method of representation described in JIS-Z-8729 is >=85 L* and ±6 a*, and the discoloration of the fiber after 5 times laundering treated by the laundering treatment regulated by JIS-L-0217-103 is class 3-4 or more evaluated by the gray scale for staining regulated by JIS-L-0805. The method for producing the fiber is also provided. The fiber has the excellent whiteness and the color stability, and further has high hygroscopicity, flame retardancy, antimicrobial activity, deodorant properties, chemical resistance or the like. The fiber can be suitably usable in a wide field such as clothes, night clothes, bedclothes, a building material, a medical good, and an industrial material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hygroscopic synthetic fiber. More specifically, while having flame retardant and antibacterial properties,
The present invention relates to a high whiteness hygroscopic synthetic fiber which has excellent workability, further improves whiteness as compared with conventional products, and has excellent color stability, in which the color hardly changes even after repeated exposure and washing in the dyeing process.

[0002]

2. Description of the Related Art Hitherto, as a means for removing moisture in the air by a fibrous material, there has been proposed a means disclosed in Japanese Patent Application Laid-Open No. Hei 1-299624 in which deliquescent salts are impregnated into superabsorbent fibers. Fibers obtained by this means are easy to process into knits, woven fabrics, non-woven fabrics, etc., have a high moisture absorption and desorption rate, and have practical performance with no loss of the moisture absorbent,
Because the fiber surface is a hydrogel, it becomes tacky when it absorbs moisture, and it is difficult to apply it especially to wallpaper and futon,
In addition, it did not satisfy flame retardancy and antibacterial properties, which have recently been increasing as social needs.

As a method for solving these problems, a means disclosed in Japanese Patent Application Laid-Open No. 5-132858 has been proposed.
However, in this method, when the amount of the salt type carboxyl group exceeds 4.5 meq / g, the tensile strength becomes 0.9 c.
N / dtex or less, resulting in insufficient fiber physical properties to withstand various types of processing, and was a barrier for further increasing the moisture absorption rate. Further, the fiber strength is 0.9 cN / d.
When the increase in the nitrogen content introduced by the treatment with the hydrazine-based compound to obtain a highly hygroscopic fiber of tex or more exceeds 8.0% by weight, the amount of salt-type carboxyl groups introduced after hydrolysis And the hygroscopicity is reduced.

Further, the fiber obtained by the method disclosed in Japanese Patent Application Laid-Open No. 5-132858 has a drawback that the field of application is limited because it exhibits a deep pink to deep brown color. The invention of Japanese Patent Application Laid-Open No. Hei 9-158040 proposed as a means for overcoming this drawback is to carry out acid treatment A after crosslinking treatment with a hydrazine-based compound, and to carry out acid treatment B after hydrolysis treatment with alkali. , And the whiteness can be considerably improved. However, even with such a technique, it is not enough to satisfy the field where severe whiteness is required. Japanese Patent Application Laid-Open No. 2000-303353 discloses that a hydrolysis treatment is performed in an oxygen-free atmosphere as a method for improving whiteness. However, the fibers obtained by this method are colored by repeating the oxidative exposure treatment and washing in the dyeing step, and thus have a disadvantage of poor color stability at present.

[0005]

DISCLOSURE OF THE INVENTION The present invention has a disadvantage that the conventional hygroscopic fiber has an unstable color while maintaining the basic physical properties required of the fiber and the properties required of the hygroscopic fiber. It is an object of the present invention to provide a fiber in which is improved and a method for producing such a fiber.

[0006]

The object of the present invention is to achieve a saturated moisture absorption at 10% by weight at 20 ° C. and 65% RH.
The above hygroscopic synthetic fiber (hereinafter, also simply referred to as hygroscopic fiber), wherein the whiteness of the fiber is JIS-Z-8729.
In the display method described in the above, L * 85 or more, a * ± 6 within the range, and the fiber after washing 5 times after washing treatment by the JIS-L0217-103 method (the detergent is used by Kao Corporation) It can be achieved by a high whiteness hygroscopic synthetic fiber (hereinafter, also referred to simply as a high whiteness hygroscopic fiber) characterized in that the discoloration is grade 3 or higher as evaluated by JIS-L0805 contamination gray scale. I can do it.

Further, the high whiteness hygroscopic synthetic fiber has a saturated water absorption of less than 300% by weight, preferably 200% by weight or less,
More preferably, the content is 150% by weight or less, and the high-whiteness hygroscopic synthetic fiber is an acrylazine-based acrylic fiber comprising an acrylonitrile-based polymer containing less than 5% by weight of a (meth) acrylate compound as a copolymerization component. That the fiber has been subjected to cross-linking treatment, hydrolysis, and reduction treatment with a base compound, and that the whiteness of the fiber after five washes is JIS-Z-
8729, wherein L * 85 or more, a
* It can be suitably achieved by being within the range of ± 6.

In addition, an acrylic fiber composed of an acrylonitrile-based polymer containing less than 5% by weight of a (meth) acrylate compound as a copolymer component is subjected to a crosslinking introduction treatment, a hydrolysis and a reduction treatment with a hydrazine-based compound. The method can be suitably achieved by a method for producing a high-whiteness hygroscopic synthetic fiber characterized by the general formula (1), but it can be achieved even more favorably by a production method in which an acid treatment is performed between the crosslinking introduction treatment and the hydrolysis treatment.

Furthermore, (1) (meth) as a copolymer component
An acrylic fiber composed of an acrylonitrile-based polymer containing less than 5% by weight of an acrylate compound is treated with a hydrazine-based compound to introduce crosslinking and increase the nitrogen content by 1.0 to 10.0% by weight. , (2) an alkali metal salt aqueous solution treatment to produce a metal salt type carboxyl group having a hydrolyzed CN group of 4.0 to 10.0 meq / g, (3) hydrosulfite salt, thiosulfate, sulfite , Nitrite, thiourea dioxide, ascorbate,
It is suitably achieved by a method for producing a high whiteness hygroscopic synthetic fiber that is subjected to a reduction treatment with a reduction treatment agent selected from the group consisting of hydrazine compounds. Note that, similarly to the above, a method of performing an acid treatment after (1) and before (2) can be naturally employed.

Further, after the reduction treatment, an acid treatment is further performed,
The metal salt type carboxyl group is converted to H-type, and Li, Na,
By treatment with a metal salt selected from K, Ca, Mg, Ba, and Al, a part of the H-type carboxyl group is converted into a metal salt form (hereinafter abbreviated as a salt form adjusting treatment) to form an H-form / metal salt form. Is more preferably achieved by a method for producing a high whiteness hygroscopic synthetic fiber in which the molar ratio is adjusted to 90/10 to 0/100.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. It is necessary that the moisture-absorbing fiber used in the present invention has a saturated moisture absorption at 10 ° C. and 65% RH of 10% by weight or more. Furthermore, the whiteness of the high whiteness hygroscopic fiber of the present invention is JIS-Z-8729.
In the display method described in 1 above, L * 85 or more and a * ± 6 must be within the range. L * is less than 85, a * is ± 6
If it is out of the range, it can no longer be said that the whiteness is excellent. Preferably, L * is 86 or more and a * is ±
4 is within the range.

Further, the high-whiteness hygroscopic fiber of the present invention is characterized in that the whiteness of the fiber is extremely small even in the washing treatment, that is, the washing durability is excellent. The discoloration of the fibers after washing five times by the JIS-L0217-103 method (the detergent used is an attack manufactured by Kao Corporation) is 3-4 or higher as evaluated by JIS-L0805 contamination gray scale. In addition, even after the washing treatment, the whiteness of the fiber is in the range of L * 85 or more and a * ± 6 in the display method described in JIS-Z-8729, preferably L * is 86 or more and a * Is desirably within the range of ± 5. Redness is the most sparse in clothing use, and the difference (Δa *) between the value of a *, which is a parameter representing redness, before and after washing is 0.7 or less, preferably 0.6. It is desirable that:

The saturated water absorption of the high-whiteness hygroscopic fiber of the present invention is preferably less than 300% by weight. If the saturated water absorption is 300% by weight or more, the fiber surface becomes sticky when water is absorbed, which is not preferable particularly for use in clothing.

It is desirable that the high-whiteness hygroscopic fiber does not decrease its whiteness even in a treatment such as oxidative exposure in the dyeing step.
5% by weight, pH 10 with NaOH, bath ratio 1/50, 8
Discoloration (exposure durability) of the fiber after exposure to hydrogen peroxide exposed at 0 ° C. for 60 minutes is evaluated as JIS-L0805 for gray scale for contamination, class 3 or higher, and water exceeding the saturated water absorption of the fiber. It is preferable that the discoloration (standing stability) after standing at 80 ° C. for 16 hours in the coexistence is 3-4 or higher as evaluated by JIS-L0805 contamination gray scale.

Here, the value (grade) of the exposure durability is NaO
A fiber sample was put into an aqueous solution of 0.5% by weight of hydrogen peroxide adjusted to pH 10 with H so that the bath ratio between the fiber sample and the aqueous solution was 1/50, and the fiber was exposed and treated at 80 ° C. for 60 minutes. This was obtained by evaluating the degree of discoloration from the color of the fiber sample before the bleaching treatment using a gray scale for JIS-L0805 contamination.

The storage stability value (grade) is determined by immersing the sample fiber in pure water, taking out the water sufficiently, and taking out the fiber. Even at 80 ° C., a sufficient amount of water to maintain water exceeding the saturated water absorption is maintained. While holding the container, it is sealed in a container so that more than half of the container is a space, placed in a thermostat adjusted to 80 ° C., taken out after 16 hours, dehydrated, and dried fiber is discolored from the fiber sample before treatment. Was obtained by evaluating the degree of JIS-L0805 gray scale for contamination. Note that the saturated water absorption is an amount obtained by subtracting the weight of the same sample fiber after drying (105 ° C. × 16 hours) from the weight after centrifugal dehydration (160 G × 5 minutes) of a sufficiently hydrated fiber. The saturated water absorption is determined by measuring the saturated water absorption by drying the sample fiber (10
The value divided by the weight after (5 ° C. × 16 hours) is expressed in%.

As a method for producing such a high-whiteness hygroscopic fiber, an acrylic fiber composed of an acrylonitrile-based polymer containing less than 5% by weight of a (meth) acrylate compound as a copolymer component is prepared by adding a hydrazine-based compound to an acrylic fiber composed of an acrylonitrile-based polymer. A method for producing a high whiteness hygroscopic fiber, which is characterized by performing a crosslinking introduction treatment, a hydrolysis treatment and a reduction treatment, is recommended. Hereinafter, the method will be described in detail.

The starting acrylic fiber (hereinafter sometimes referred to as acrylonitrile fiber) is formed of an AN polymer containing acrylonitrile (hereinafter, referred to as AN) in an amount of 40% by weight or more, preferably 50% by weight or more. The fibers may be in any form such as short fibers, tows, yarns, knitted fabrics and nonwoven fabrics, and may be in-process products or waste fibers. The AN-based polymer may be any of an AN homopolymer and a copolymer of AN and another monomer, and a (meth) acrylate compound is most preferably used as a monomer to be copolymerized with AN. However, if it is unavoidable to use it, it must be less than 5% by weight, more preferably 4.0% by weight or less. The notation with (meth) indicates both acrylate and methacrylate. Examples of the ester compound which may be used as a copolymer component if it is less than 5% by weight include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylate, and the like.
Examples thereof include dimethylaminoethyl acrylate and diethylaminoethyl (meth) acrylate. Other copolymerizable components include sulfonic acid group-containing monomers such as methallyl sulfonic acid and p-styrene sulfonic acid and salts thereof; monomers such as styrene and vinyl acetate and the like which are copolymerizable with AN. It is not particularly limited as long as it is a compound, but it is desirable to copolymerize 5 to 20% by weight of a vinyl ester compound represented by vinyl acetate. Such vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, and the like.

The acrylic fiber is subjected to a cross-linking treatment with a hydrazine-based compound, and a cross-link is formed in the sense that the acrylic fiber is no longer dissolved in a solvent for the acrylic fiber, and at the same time, the nitrogen content increases. But,
The means is not particularly limited. A means capable of adjusting the increase in the nitrogen content by this treatment to 1.0 to 10% by weight is preferable, but the increase in the nitrogen content is preferably 0.1 to 1.0% by weight.
Even if it is weight%, it can be adopted as long as it is a means for obtaining the high whiteness hygroscopic fiber of the fiber of the present invention. The means by which the increase in nitrogen content can be adjusted to 1.0 to 10% by weight includes
In an aqueous solution of a hydrazine compound having a concentration of 5 to 60% by weight,
Means of treating at a temperature of 50 to 120 ° C. within 5 hours is industrially preferable. In order to suppress the increase in the nitrogen content at a low rate, these conditions may be set in a milder direction according to the teaching of reaction engineering. Here, an increase in the nitrogen content refers to a difference between the nitrogen content of the raw acrylic fiber and the nitrogen content of the acrylic fiber into which the crosslinking with the hydrazine compound has been introduced.

The hydrazine compound used herein is not particularly limited, and may be, for example, hydrazine hydrate, hydrazine sulfate, hydrazine hydrochloride, hydrazine bromate, hydrazine carbonate, etc., as well as ethylenediamine, guanidine sulfate, guanidine hydrochloride, phosphorus Compounds having a plurality of amino groups such as guanidine acid and melamine are exemplified.

The fiber which has been subjected to the cross-linking treatment with a hydrazine compound may be subjected to an acid treatment. This treatment contributes to improving the color stability of the fiber. Examples of the acid used here include aqueous solutions of mineral acids such as nitric acid, sulfuric acid, and hydrochloric acid,
Examples thereof include organic acids, but are not particularly limited. Before this treatment, the hydrazine-based compound remaining in the crosslinking introduction treatment is sufficiently removed. The conditions for the acid treatment are not particularly limited, but are generally 5 to 20% by weight, preferably 7 to 7% by weight.
0.5 to 15 wt% aqueous solution at a temperature of 50 to 120 ° C.
Examples of immersing the fiber to be treated for up to 10 hours are given.

The fiber which has undergone the cross-linking treatment step with a hydrazine-based compound, or the fiber which has been further subjected to an acid treatment, is subsequently hydrolyzed with an aqueous alkali metal salt solution. By this treatment, the CN group remaining without being involved in the cross-linking introduction treatment of the acrylic fiber by the hydrazine-based compound treatment, and remaining when an acid treatment is performed after the crosslinking treatment step
The hydrolysis of the CN group and the CONH ₂ group partially hydrolyzed by the acid treatment proceeds. These groups form a carboxyl group by hydrolysis, but since the drug used is an alkaline metal salt, a metal salt-type carboxyl group is eventually formed. Examples of the alkaline metal salt used here include an alkali metal hydroxide, an alkaline earth metal hydroxide, and an alkali metal carbonate. The concentration of the alkaline metal salt to be used is not particularly limited, but is preferably 1 to 10% by weight, more preferably 1 to 5% by weight in an aqueous solution at a temperature of 50 to 120%.
Means of treating within 1 to 10 hours at a time is preferable in terms of industrial and fiber properties.

Here, the kind of the metal salt, that is, the salt type of the carboxyl group includes alkali metals such as Li, Na and K, M
Alkaline earth metals such as g, Ca and Ba can be mentioned. The extent to which hydrolysis proceeds, that is, the amount of metal salt-type carboxyl groups to be formed, should be controlled to 4 to 10 meq / g,
This can be easily performed by a combination of the drug concentration, temperature, and processing time in the above-described processing. The fibers that have undergone such a hydrolysis step may or may not have CN groups remaining. If CN groups remain, their reactivity may be used to provide additional functions.

The reducing agent used in the subsequent reduction treatment is selected from the group consisting of hydrosulfite salts, thiosulfates, sulfites, nitrites, thiourea dioxide, ascorbate, and hydrazine compounds. Drugs of a kind or a combination of two or more kinds can be suitably used. The conditions for the reduction treatment are not particularly limited, and examples include immersing the fiber to be treated in an aqueous solution having a drug concentration of approximately 0.5 to 5% by weight at a temperature of 50 ° C to 120 ° C for 30 minutes to 5 hours. . The reduction treatment may be performed simultaneously with the above-mentioned hydrolysis or after the hydrolysis.

Thus, the high-whiteness hygroscopic fiber of the present invention is obtained. In order to further stabilize the color, the fiber which has been subjected to the above-mentioned reduction treatment step is subjected to an acid treatment to convert the metal salt type carboxyl group into H. Mold, Li, Na, K, Ca, Mg, B
a, by treating with a metal salt selected from Al, a part of the H-type carboxyl group is converted into a metal salt form (salt-type adjusting treatment) to make the molar ratio of H-type / metal salt form 90/10 to 0/100. Adjustment is preferred.

Examples of the acid used for the acid treatment include aqueous solutions of mineral acids such as nitric acid, sulfuric acid, and hydrochloric acid, and organic acids, but are not particularly limited. The conditions of the acid treatment are not particularly limited, but are generally in an aqueous solution having an acid concentration of 1 to 10% by weight, preferably 2 to 10% by weight, at a temperature of 50 to 120 ° C.
Examples of immersing the fiber to be treated for up to 10 hours are given.

The metal type of the metal salt used in the salt type adjustment treatment includes Li, Na, K, Ca, Mg, Ba,
Although selected from Al, Na, K, Ca, Mg and the like are particularly recommended. The type of salt may be any water-soluble salt of these metals, such as hydroxide, halide, nitrate, sulfate, carbonate and the like. Specifically, a typical example of each metal is NaO as NaO.
H, Na ₂ CO ₃ , K salts are preferred as K salts, and Ca (OH) ₂ , Ca (NO ₃ ) ₂ , and CaCl ₂ are preferred as Ca salts.

The H-type / metal salt molar ratio of the carboxyl group is within the above-mentioned range, but is appropriately set together with the type of metal depending on the function to be imparted to the fiber. In the concrete implementation of the salt type adjustment treatment, 0.2 to
There is a method of preparing a 30% by weight aqueous solution and dipping the fiber to be treated at 20 ° C. to 80 ° C. for about 0.25 to 5 hours, or spraying the aqueous solution. In order to control the above ratio, a salt type adjustment treatment in the presence of a buffer is preferable.
As the buffer, those having a pH buffer range of 5.0 to 9.2 are preferable. Further, the kind of the metal salt of the metal salt type carboxyl group is not limited to one kind, and two or more kinds may be mixed.

The high whiteness hygroscopic fiber of the present invention described above has excellent absorbability, flame retardancy and antibacterial properties, is excellent in processability, and has improved whiteness and color stability compared to conventional products. Also excellent hygroscopic fiber.

When the salt type adjusting treatment is carried out with a substance having low water solubility such as a metal salt compound such as Ca, Mg, Ba, etc., the molar ratio of H type / metal salt type is changed from H type carboxyl group to H type carboxyl group in this step. Has some difficulty in increasing the metal salt form. In such a case, as a pretreatment after the acid treatment and as a pretreatment of the salt form adjustment treatment, the pH of the carboxyl group converted into the H-form in the acid treatment step is adjusted with an aqueous solution of caustic soda or potassium hydroxide, that is, the pH of the carboxyl group is adjusted, that is, the pH is adjusted. It is recommended to perform a sum treatment (pH = 5th to 11th). With such a formulation, the carboxyl group after neutralization treatment is H-type and N-type.
Since the a or K type coexists, the next salt type adjustment process easily proceeds by exchanging Ca or the like with Na or K, and the difficulties raised are solved.

The means for producing the acrylic fiber, which is the starting material, is not particularly limited, and any means used for producing ordinary fibers for clothing can be used. Further, it is preferable to use such a fiber as a starting fiber, but it is not always necessary to finish the final step, and even if an acrylic fiber is being produced, or the final fiber is subjected to spinning or the like. The later one may be used. Above all, as the starting acrylic fiber, a fiber before drawing and heat treatment after drawing in the middle of the acrylic fiber manufacturing process (an original spinning solution of an AN polymer is spun according to a conventional method, drawn and oriented, dried and densified, wet heat relaxation treatment, etc. Fibers not subjected to heat treatment, especially water-swollen gel-like fibers after wet or dry / wet spinning and drawing:
When the water swelling degree is 30 to 150%), the dispersibility of the fibers in the treatment liquid and the permeability of the treatment liquid into the fibers are improved, so that the introduction of cross-linking and the hydrolysis reaction are uniform and rapid. This is desirable.

These starting acrylic fibers are filled in a container having a stirring function and a temperature control function, and the above-described steps are sequentially performed, or a plurality of containers are arranged and continuously performed. Taking safety on equipment,
It is desirable from various points such as uniform processing property. As such an apparatus, a dyeing machine is exemplified.

As another method for producing the high-whiteness hygroscopic fiber of the present invention, the acrylic fiber is subjected to the above-mentioned cross-linking treatment with a hydrazine-based compound, hydrolysis, reduction treatment, and acid treatment. A method in which the reduction treatment and the acid treatment are repeated is exemplified. By repeating the reduction treatment and the acid treatment, whiteness and color stability are improved, and L * 85 or more, a * ±
6, and a high whiteness hygroscopic fiber having a washing durability of 3-4 class or higher can be obtained. According to this method, the (meth) acrylate compound is a copolymer component of the acrylonitrile-based polymer forming the acrylic fiber.
Even when the content is not less than 10% by weight, the high whiteness hygroscopic fiber of the present invention can be obtained, but since the reduction treatment and the acid treatment need to be repeated, the fiber physical properties are reduced and the production cost is high. Therefore, it is more advantageous to adopt the above-described manufacturing method recommended by the present invention.

The fiber of the present invention is a high whiteness hygroscopic fiber having a high elongation to withstand fiber processing and excellent color stability, and generates heat as moisture is absorbed. It also has flame retardancy, antibacterial properties, deodorant properties, chemical resistance, and the like, which are considered to be caused by a nitrogen-containing crosslinked structure and a high moisture absorption rate. For this reason, the fiber of the present invention is used for general clothing such as underwear, underwear, lingerie, pajamas, baby products, girdle, bra, gloves, socks, tights, leotards, trunks, sweaters, sweatshirts, polo shirts, suits, sportswear, and mufflers. ,
For middle and foreign clothing, handkerchiefs, towels, curtains, futons, futons, pillows, cushions, plush toys, bedding, packing, sheets, blankets, pads, etc.
Mats, supporters, interlining, insoles, insoles,
It is suitably applied to building materials such as slippers and wallpapers, and applications to the medical field.

[0035]

The high-whiteness hygroscopic fiber of the present invention described in detail above
Although the reason for having excellent whiteness and color stability has not been sufficiently elucidated, it is generally considered as follows. That is,
When a crosslinked structure is introduced by a hydrazine compound,
Acrylic fiber as raw material is used as copolymer component (meth)
When the acrylate compound is contained in an amount of 5% by weight or more, the hydrazine-based compound reacts with the carbonyl carbon portion of the copolymer component, and as a result, a bond containing an oxygen molecule is introduced into the crosslinked structure, so that the color is easily formed. Although the stability is inferior, in the production method recommended by the present invention, color formation is suppressed because the formation of the bond is suppressed at the raw material stage, and it is difficult to develop color even by treatment such as hydrogen peroxide exposure treatment or washing repeatedly. Presumed. Even when the (meth) acrylic acid ester compound is contained in an amount of 5% by weight or more, the reduction and acid treatments are repeated to form a molecular structure that develops a color even by treatments such as hydrogen peroxide exposure treatment and repeated washing. It is presumed that this is because it has a stable molecular structure that does not easily change.

[0036]

The present invention will be described in detail with reference to the following examples. Parts and percentages in the examples are on a weight basis unless otherwise specified. The metal salt type carboxyl group content, whiteness and moisture absorption were determined by the following methods.

(1) Metal salt type carboxyl group content (meq
/ G) About 1 g of sufficiently dried fiber after hydrolysis is precisely weighed (X
g), 200 ml of water was added thereto, and a 1 mol / l aqueous hydrochloric acid solution was added thereto while heating at 50 ° C. to adjust the pH to 2, and then a titration curve was obtained with a 0.1 mol / l aqueous sodium hydroxide solution according to a conventional method. From the titration curve, the consumption amount (Yml) of the aqueous solution of caustic soda consumed by the carboxyl groups was determined, and the carboxyl group amount (meq / g) was calculated by the following equation. (Amount of carboxyl group) = 0.1 Y / X Separately, 1 mol /
Similarly, the titration curve was determined without adjusting the pH to 2 by adding an aqueous hydrochloric acid solution, and the amount of H-type carboxyl group (meq
/ G). From these results, the amount of metal salt-type carboxyl groups was calculated by the following equation. (Amount of metal salt type carboxyl group) = (Amount of carboxyl group)
-(H-type carboxyl group amount)

(2) Whiteness 4.0 g of a sample fiber defibrated by a card machine was filled in a rotary colorimetric cell (35 ml transparent cylindrical cell), and a color difference meter TC-1500MC-88 manufactured by Tokyo Denshoku Co., Ltd. was used. (D65 light source) The color was measured while rotating at a rate of 60 times / minute. This measurement was repeated three times, and the values of L * and a * (average values) were determined. (3) Moisture Absorption (%) About 5.0 g of the sample fiber was dried at 105 ° C. for 16 hours with a hot air drier, and the weight was measured (W1 g). Next, the sample was heated to temperature 2
Place in a constant humidity bath at 0 ° C. and 65% RH for 24 hours. The weight of the sample thus absorbed is measured (W2 g).
From the above measurement results, it was calculated by the following equation. (Moisture absorption%) = {(W2-W1) / W1} × 100

Example 1, Comparative Example 1 AN polymer comprising 96% by weight of AN and 4% by weight of methyl acrylate (hereinafter referred to as MA) (intrinsic viscosity [η] in dimethylformamide at 30 ° C .: 1.2) 10 copies to 4
After spinning and stretching (total stretching ratio: 10 times) a spinning stock solution dissolved in 90 parts of an 8% aqueous solution of rodin soda, drying and wet heat treatment are performed under an atmosphere of dry bulb / wet bulb = 120 ° C./60° C. Thus, a raw fiber having a single fiber fineness of 1.7 dtex was obtained.

The raw material fiber was subjected to a crosslinking introduction treatment at 98 ° C. for 5 hours in a 20% by weight aqueous solution of hydrazine hydrate.
This treatment introduces crosslinking and increases the nitrogen content. The nitrogen increase was calculated from the difference between the nitrogen content of the raw fiber and the fiber after the cross-linking treatment by elemental analysis. Next, in a 3% by weight aqueous solution of caustic soda, 90 ° C.
A × 2Hr hydrolysis treatment was performed, and the resultant was washed with pure water. By this treatment, 5.5 meq of Na-type carboxyl groups are added to the fiber.
/ G.

The hydrolyzed fiber was subjected to a reduction treatment at 90 ° C. for 2 hours in a 1% by weight aqueous solution of hydrosulfite sodium salt (hereinafter referred to as SHS) and washed with pure water. Subsequently, in a 3% by weight aqueous solution of nitric acid, 90 ° C. × 2H
r Acid treatment was performed. As a result, the total amount of the Na-type carboxyl groups generated at 5.5 meq / g was H-type carboxyl groups. The fiber after the acid treatment is put into pure water, and a 48% aqueous solution of caustic soda is added to the H-type carboxyl group so that the degree of Na neutralization is 70 mol%.
A 0 ° C. × 3 Hr salt type adjustment treatment was performed.

The fiber having undergone the above steps was washed with water, applied with an oil agent, dehydrated and dried to obtain the high whiteness hygroscopic fiber of Example 1.
The moisture absorption, whiteness, and color stability of the obtained fiber were examined, and the results are shown in Table 1 together with the amount of salt-type carboxyl groups and the amount of increase in nitrogen.
Comparative Example 1 is a hygroscopic fiber obtained in the same manner as in Example 1 except that an AN-based polymer composed of 94% by weight of AN and 6% by weight of MA was used.

Examples 2 and 3 High whiteness hygroscopic fibers of Example 2 were obtained in the same manner as in Example 1 except that the salt type adjustment treatment was performed with caustic potash. In Example 3, the fiber of Example 1 was treated with an aqueous solution of calcium chloride to convert the Na-type carboxyl group into a Ca-type carboxyl group. The properties of these fibers are also shown in Table 1.

Examples 4 and 5 High whiteness hygroscopic fibers of Examples 4 and 5 were obtained in the same manner as in Example 1 except that the reducing agent was changed to the chemical listed in Table 1. The properties of these fibers are also shown in Table 1. In the table, hydrated hydrazine is represented by HH, and sodium thiosulfate is represented by STS.

Example 6 The procedure was carried out except that sodium thiosulfate was used as the reducing agent and the salt-type adjusting treatment conditions were changed so that the molar ratio between the amount of H-type carboxyl groups and the amount of Ca salt-type carboxyl groups was 50/50. In the same manner as in Example 1, the high whiteness hygroscopic fiber of Example 6 was obtained. Here, the salt type adjustment treatment is performed with a Na neutralization degree of 50 mol%.
After the treatment under the following conditions, the mixture was treated with an aqueous calcium chloride solution to convert the Na-type carboxyl group into a Ca-type carboxyl group. The properties of these fibers are also shown in Table 1.

Examples 7 and 8 Fibers which had been subjected to a cross-linking treatment with hydrazine hydrate were
A high whiteness hygroscopic fiber of Example 7 was obtained in the same manner as in Example 1, except that an acid treatment was performed in a 10% by weight aqueous nitric acid solution at 90 ° C. for 2 hours before hydrolysis. The fiber of Example 8 is obtained by converting the fiber of Example 7 into a Ca-type carboxyl group using the method described in Example 3. The properties of these fibers are also shown in Table 1.

[0047]

[Table 1]

The high-whiteness hygroscopic fiber of Example 1 showed a moisture absorption of 35%, and the whiteness was also good as L * 88.4 and a * 0.99. In addition, the fibers exhibited excellent exposure stability, washing durability, and standing stability of 3-4 class, 4-5 class, and 4-5 class, respectively. In Examples 2 and 3 in which the type of metal salt was different from that in Example 1, although the moisture absorption was slightly lower than that in Example 1, the whiteness and the color stability were the same as those of Example 1 fiber. . In Examples 4 and 5, in which the type of the reducing agent was different from that in Example 1, the whiteness and the color stability were slightly inferior to Example 1, but at a usable level. Example 6 has a calcium salt-type carboxyl group and the molar ratio of the H-type carboxyl group is as high as 50 mol%. The moisture absorption of Example 6 is 20%, and the moisture absorption, whiteness, and color stability are at usable levels. there were. In Examples 7 and 8 in which the fiber that had undergone the cross-linking introduction treatment was subjected to an acid treatment before hydrolysis, the whiteness was not much different from Examples 1 and 3, but the color stability was still higher. On the other hand, in Comparative Example 1, a raw material fiber containing 6% by weight of MA as an acrylate compound was used. Although the whiteness was good, the bleaching durability, washing durability and shelf stability were inferior in color stability to 2nd, 3rd and 3rd grades, respectively, and were inferior in the processing stage or the final product use stage. Level.

Examples 9 and 10 In the same manner as in Example 1 except that thiourea dioxide (hereinafter referred to as UTO) was used as a reducing agent and the composition of the AN polymer was changed as shown in Table 2. , Example 9,
A high whiteness hygroscopic fiber of 10 was obtained. Table 2 shows the properties of this fiber.
It was also described in. In the table, vinyl acetate is abbreviated as VAC.

Example 11 The hydrazine hydrate concentration and the treatment time under the cross-linking treatment conditions were adjusted so that the amount of increase in nitrogen became the amount shown in Table 2, and the salt-type adjustment treatment was carried out so that the Na-type carboxyl group was 30 mol%. Example 11 was repeated in the same manner as in Example 10 except that the conditions were changed.
High whiteness hygroscopic fiber was obtained. The properties of this fiber are also shown in Table 2.

Examples 12 and 13 The procedure of Examples 12 and 13 was repeated except that UTO was used as the reducing agent and that the hydrazine hydrate concentration and the treatment time under the crosslinking introduction treatment conditions were adjusted so that the amount of increase in nitrogen was as shown in Table 2. In the same manner as in Example 1, high whiteness hygroscopic fibers of Examples 12 and 13 were obtained.
The properties of these fibers are also shown in Table 2.

[0052]

[Table 2]

In Example 9, a raw material acrylic fiber containing no acrylate compound and containing 10% by weight of VAC was used, and UTO was used as a reducing agent. The moisture absorption was as high as 35%, and the whiteness was high. Is excellent in L * 87.6 and a * 0.91, and also has excellent color stability such as washing durability, exposure durability and shelf stability of 4-5 class, 4th class and 4-5 class, respectively. Fiber. In Example 10, although the raw acrylic fiber containing 2% by weight of MA was used, it had a high moisture absorption, and maintained high whiteness and excellent color stability. In Example 11, the Na type carboxyl group was adjusted to 30 mol% by the salt type adjustment treatment, and the moisture absorption became 24%, but excellent whiteness and color stability were maintained. In Examples 12 and 13, UTO was used as the reducing agent, the amount of increase in nitrogen was 2.9% by weight, respectively, and the amount of metal salt-type carboxyl groups was 8.8.
5, 4.2 meq / g. These maintained excellent whiteness and color stability.

Example 14 A high whiteness hygroscopic fiber of Example 14 was obtained in the same manner as in Example 9 except that the acid treatment and the salt type adjustment treatment after the reduction treatment were not performed. The properties of this fiber are shown in Table 3.

Example 15 A fiber which had been subjected to a cross-linking treatment process using hydrated hydrazine was
A high whiteness hygroscopic fiber of Example 15 was obtained in the same manner as in Example 14, except that acid treatment was performed in a 10% by weight aqueous nitric acid solution at 90 ° C for 2 hours. The properties of these fibers are also shown in Table 3.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the composition of the AN-based polymer was set to AN / MA = 93/7, and the acid treatment and the salt type adjustment treatment after the reduction treatment were not carried out. A synthetic fiber was obtained.

Comparative Examples 3 and 4 The hydrazine hydrate concentration and the treatment time under the cross-linking treatment conditions were adjusted so that the amount of increase in nitrogen became the amount shown in Table 3, and the reduction treatment agent shown in Table 3 was used. In the same manner as in Comparative Example 2, fibers of Comparative Examples 3 and 4 were obtained. Table 3 shows the properties of this fiber.
It was also described in.

Comparative Example 5 A hygroscopic fiber of Comparative Example 5 was obtained in the same manner as in Example 1 except that the reduction treatment, the acid treatment and the salt type adjustment treatment were not performed. The properties of this fiber are also shown in Table 3.

Example 16 and Comparative Example 6 A hygroscopic fiber of Comparative Example 6 was obtained in the same manner as in Example 7 except that the composition of the AN polymer was changed to AN / MA = 94/6.
The fiber obtained in the same manner as in Comparative Example 6 except that the salt type adjustment treatment was not performed, was again subjected to 9% aqueous solution of SHS in 9% by weight.
Perform a 0 ° C. × 2 hr reduction treatment, wash with pure water,
In a 3% by weight aqueous solution of nitric acid, an acid treatment at 90 ° C. for 2 hours was performed, and a salt type adjustment treatment was further performed to obtain a high whiteness moisture absorbing / releasing fiber of Example 16. The properties of these fibers are also shown in Table 3.

[0060]

[Table 3]

The moisture absorption of the high-whiteness hygroscopic fiber of Example 14 was 42%, and had a sufficient whiteness of L * 87.3 and a * 1.18. Although the color stability was slightly inferior to that of Example 9, the washing durability was 4th grade, the exposure durability was 3rd grade, and the storage stability was 3-4th grade. The fiber of Example 15 shows excellent moisture absorption and whiteness as in Example 14,
In addition, color stability is 4th in washing durability, 3-4 bleaching durability.
Grade, storage stability 4th grade, and better stability than Example 14. The fiber of Example 16 had 6% by weight of MA. However, by repeating the reduction treatment and the acid treatment, the (meth) acrylate compound was less than 5% by weight. It had degree and color stability.

The fibers of Comparative Examples 2 and 3 exhibited good whiteness but were extremely inferior in color stability of the fibers, and Comparative Example 3 had poor handling properties at the time of absorbing moisture and were difficult to employ in practice. became. Further, the fiber of Comparative Example 4 had a low moisture absorption of 10%, and was L * 84.1 and a * 8.23, which was not very high in whiteness. Comparative Example 5 was colored red because the reduction treatment was omitted. Since the fiber of Comparative Example 6 did not repeat the reduction treatment and the acid treatment as compared with Example 16, the whiteness was good, but the color stability was poor.

[0063]

Conventionally, hygroscopic fibers are disclosed in JP-A-200
What is obtained by the technique of 0-303353 is
Although it has been considered that moisture absorption performance and whiteness are well-balanced, with the advent of the present invention, the color change occurs even when the moisture absorption performance is maintained and the exposure in the dyeing process and the repeated washing with the final product are performed. No, that is, a fiber having excellent color stability can be provided. The fiber according to the present invention can be suitably used without any limitation in use. In the production of the fiber of the present invention, the product fiber once adjusted to the “metal salt type” of the specific carboxyl group and the “molar ratio” of the specific H type / metal salt type may be combined with the product fiber if required. It is also an industrial advantage that it can be readjusted to a different "molar ratio" or "metal salt type".

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L031 AA17 AB03 AB04 BA11 BA17 BA36 CA01 CA03 DA08 4L033 AA05 AB01 AC07 AC15 BA49

Claims (7)

[Claims] 1. A hygroscopic synthetic fiber having a saturated moisture absorption of 10% by weight or more at 20 ° C. and 65% RH, wherein the whiteness of the fiber is L * 85 in the display method described in JIS-Z-8729. Above, within the range of a * ± 6 and JI
A high whiteness hygroscopic synthetic fiber characterized in that the discoloration of the fiber after washing five times, which has been subjected to the washing treatment by the S-L0217-103 method, is grade 3 or higher as evaluated by JIS-L0805 contamination gray scale. 2. A high whiteness hygroscopic synthetic fiber having a saturated water absorption of 3
The high-whiteness hygroscopic synthetic fiber according to claim 1, wherein the content is less than 00% by weight. 3. A cross-linking treatment of a high whiteness hygroscopic synthetic fiber with a hydrazine compound into an acrylic fiber made of an acrylonitrile polymer having a (meth) acrylate compound content of less than 5% by weight as a copolymer component. The high-whiteness hygroscopic synthetic fiber according to claim 1 or 2, which has been subjected to hydrolysis, reduction treatment. 4. The fiber whiteness after washing 5 times is JIS-Z-
8729, wherein L * 85 or more, a
4. The method according to claim 1, wherein the distance is within a range of ± 6.
The high-whiteness hygroscopic synthetic fiber according to any one of the above. 5. An acrylic fiber comprising an acrylonitrile-based polymer containing less than 5% by weight of a (meth) acrylate compound as a copolymerization component, is subjected to a crosslinking introduction treatment, a hydrolysis and a reduction treatment with a hydrazine-based compound. A method for producing a high whiteness hygroscopic synthetic fiber, characterized by comprising: 6. An acrylic fiber composed of an acrylonitrile-based polymer containing less than 5% by weight of a (meth) acrylate compound as a copolymerization component is treated with a hydrazine-based compound to introduce a crosslink. (2) Treatment with an aqueous alkali metal salt solution to produce 4.0 to 10.0 meq / g of a metal salt type carboxyl group having a CN group hydrolyzed. ,
(3) High whiteness characterized by being reduced with a reducing agent selected from the group consisting of hydrosulfite salts, thiosulfates, sulfites, nitrites, thiourea dioxide, ascorbate, and hydrazine compounds. Method for producing a hygroscopic synthetic fiber. 7. After the reduction treatment, an acid treatment is further performed to convert the metal salt-type carboxyl group into an H-type, and form Li, Na, K, C
a, a part of the H-type carboxyl group is converted to a metal salt form by treatment with a metal salt selected from a, Mg, Ba, and Al.
The method for producing a high whiteness hygroscopic synthetic fiber according to claim 5 or 6, wherein the molar ratio of the mold / metal salt type is adjusted to 90/10 to 0/100.