JPH09228141A - Moisture and water absorbing fiber and fiber product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a moisture and water absorbing fiber holding a fiber shape after absorbing water, having a specific coefficient of water absorption, capable of freely selecting a moisture absorbing speed, repeatedly absorbing and desorbing moisture, having a large calorific value at moisture and water absorption, excellent in washing resistance and useful for a drying material, a humidity conditioning material, etc. SOLUTION: This moisture and water absorbing fiber is obtained by using, e.g. (meth)acrylic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid and 2-hydroxypropyl (meth)acrylate as a crosslinking agent, can hold a fiber shape after absorbing water and has >=35wt%. moisture absorption rate at 65% relative humidity and >=800wt.% water absorption of 0.9% saline. Fiber products such as a nonwoven fabric, a knit and woven fabric, a bedding, a filter, etc., can be obtained by allowing to contain >=5% of the moisture and water absorbing fiber.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hygroscopic and water-absorbent fiber used as a desiccant, a humidity control agent and a fiber product containing the same, such as a nonwoven fabric, a knitted fabric, a futon, a filter and the like.

[0002]

2. Description of the Related Art As the water-absorbent fiber, a water-absorbent fiber made of sodium polyacrylate is commercially available from Kanebo Co., Ltd. under the trademark "Bell Oasis". This fiber has a high moisture absorption rate, 40% by weight at 20 ° C and 60% relative humidity.
And it shows a very high hygroscopicity compared to other fibers. Further, when moisture is gradually absorbed at 30 ° C. and a relative humidity of 100%, a very large maximum moisture absorption rate exceeding 500% by weight is exhibited. In addition, this fiber is 100% even after centrifugation of saline.
It exhibits a very large water absorption that the content is maintained so as to exceed 0% by weight. However, this water-absorbent fiber has a serious drawback that the fiber strength almost disappears when it absorbs water. Therefore, it is not suitable for washing.

A water absorbing fiber obtained by hydrolyzing polyacrylonitrile fiber and gelling a portion close to the surface is Toyobo Co., Ltd.
Is marketed under the trademark "Lanceir" from. However, this water-absorbent fiber is not very hygroscopic. When actually measured, the hygroscopicity is about 1/3 or less that of "Bell Oasis".

As the hygroscopic fiber, N from Toyobo Co., Ltd.
Although the fiber No. 38 is commercially available, it is a modified fiber similar to the above-mentioned "Lanseal". Textile Society, 1995 VOL. 51, May issue, pages 211 to 212, its outline is described.

The characteristic of this fiber is its hygroscopic property,
It has a moisture absorption of 38% by weight at a relative humidity of 60% and is described as having excellent hygroscopicity. In addition, the calorific value measured using a C-80 calorimeter under the conditions of 25 ° C. and 80.5% relative humidity is 345 cal per 1 g of dry fiber, which is far larger than 114.8 cal of wool. Has been done. In addition, this calorific value corresponds to the water content, and the adsorption heat (heat generation) per 1 g of water due to the material is 67
At 9 cal, the wool is described as 663 cal. The disadvantage is that the color is pink.
As a result of measuring the water absorption rate of this fiber in physiological saline, it was found that the fiber which had been conditioned at a standard condition of 23 ° C. and a relative humidity of 65% had a small water absorption rate of 48% by weight after centrifugal dehydration.

A heat insulation product using this fiber is disclosed in Japanese Patent Publication No. 7-5.
No. 9762. This fiber is described as having an exotherm associated with hydrogen bonding, heat of solution, and van der Waals force when it is transferred from an absolutely dry state to water or a high-humidity atmosphere. In addition, when placed in 100 g of water kept at 20 ° C. in an environment of 20 ° C. and 40% relative humidity, the calorific value is different in the unit of calorific value, but this fiber is about 60 J
/ G, wool is described as about 15 J / g, humidity is 80.5
%, But the amount of heat generation is smaller than the value published by the academic conference above. Since this fiber already contains 22% by weight of water and wool contains 12% by weight of water in an environment of 20 ° C. and 40% relative humidity, heat generation corresponding to that in an absolutely dry state This is because the amount of heat generated is small because of the absence of heat (corresponding to about 30 J / g for this fiber). However, conversely, in addition to the heat generation a due to moisture absorption, the heat generation b due to water absorption and dissolution is added, and thus this value is obtained. However, since the amount of water absorption is small, the heat generation b is small. Therefore, there is a drawback that a large amount of sweat b or heat generation b in a wet suit cannot be expected.

Further, in this publication, for example, in the case of ski wear as a heat insulating product, it is described that a calorific value of 16 to 24 kJ is practical. In this case, it is assumed that the clothing climate is 20 ° C. and the relative humidity is increasing from 40 to 90%. Therefore, sweat is flowing and the relative humidity is 100.
We do not assume a situation where it will be%.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hygroscopic and water-absorbent fiber used as a desiccant, a humidity control agent and an exothermic agent and a fiber product thereof at a low price.

[0009]

Means for Solving the Problems The present inventors have conducted a study on a modification method for improving the strength reduction at the time of water absorption, which is a drawback of the water absorbing fiber "Belle Oasis", and have completed the present invention.
The hygroscopic and hygroscopic fiber of the present invention retains the fiber form even after absorbing water,
It is a hygroscopic water-absorbent fiber having a moisture absorption rate of 35% by weight or more at 20 ° C. and a relative humidity of 65% and a water absorption rate of 0.9% physiological saline of 800% by weight or more.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the hygroscopic water-absorbent fiber of the present invention, a monomer having a composition similar to that of the water-absorbent polymer is used.
As the carboxylic acid, for example, (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, sorbic acid, cinnamic acid, crotonic acid, beta-acryloxypropionic acid, and alkali metal salts thereof can be used. . Preferably (meth) acrylic acid is economically recommended.

Partly as a sulfonic acid, for example, 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylsulfonic acid, ethyl (meth) acrylate sulfonate, styrenesulfonic acid, vinylsulfonic acid, 2- (meth) acryloyl propane sulfonic acid and alkali metal salts thereof can be used. The inclusion of sulfonic acid is preferable because it improves the water absorption of physiological saline.

As the cross-linking agent, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate and adducts of ethylene oxide and propylene oxide thereof are used. If the amount of the cross-linking agent is too large, the water absorption rate will decrease, so it must be selected appropriately.
In the case of a water-absorbing polymer, a polyfunctional group is used, but in the case of a fiber, it is preferable that the polyfunctional group is not a polyfunctional group because gelation is less likely to occur.

The cross-linking is carried out when the spinning is completed and the fiber formation is completed. Since the crosslinking is an ester bond, the crosslinking is accelerated by dehydration by heating. As a water absorbing fiber similar to this, there is “Bell Oasis” manufactured by Kanebo Co., Ltd.
The characteristic feature of this water-absorbent fiber is that it is highly water-absorbent, and its hygroscopicity is a secondary effect. On the other hand, high hygroscopicity adversely affects spinning properties and the like, so various studies have been conducted to suppress the degree of crosslinking so as to suppress hygroscopicity and increase water absorption.

The hygroscopic and water-absorbent fiber of the present invention was able to maintain its morphology during water absorption and its moisture absorption rate by advancing this cross-linking properly by selecting heat treatment conditions. This heat treatment may be performed by dividing it into multiple stages, and it can also be produced by further heat-treating the above-mentioned "bell oasis". However, if heat treatment is excessively performed, crosslinking partially proceeds, but crosslinking is partially destroyed,
It was found that the shape retention was poor. When the heat treatment conditions used in the production of the moisture absorbent and water absorbent fiber of the present invention are 210 ° C. or higher, the temperature is Y ° C., and the treatment time is X minutes, 210 ≦ Y <308− (80/110) X 5 ≦ X ≦ 120 It is preferable to carry out in the range. When the heat treatment temperature and the heat treatment time are less than this range, the strength is significantly reduced when absorbing water, and the morphological stability is not sufficient. If the heat treatment temperature and heat treatment time are larger than this range, the shape retention and moisture absorption are adversely affected.

This heat treatment can be carried out by a hot air circulation type suction hot air dryer, but when cotton is laminated, hot air is blown from above the cotton, and suction is performed from below, it is preferable because the unevenness of heat treatment is small. When this type of heat treatment machine is used, the treatment time can be shortened, but in order to obtain appropriate shape retention, it is preferable to carry out in the range of 210≤Y≤295-X5≤X≤80.

The hygroscopic water-absorbent fiber of the present invention has the same hygroscopicity as the raw material "Belle Oasis" fiber and has a water content of 35% by weight or more at 20 ° C. and a relative humidity of 65%. When it is made to absorb moisture gradually, it exhibits a moisture absorption rate of 500% or more. Further, although the degree of cross-linking is progressing, the water absorption of physiological saline tends to decrease, but it hardly decreases at 800% by weight or more. The water absorption of ion-exchanged water is significantly reduced by the progress of crosslinking,
The raw material "Belle Oasis" fiber is more than 4000% by weight, but the hygroscopic water absorbent fiber of the present invention is reduced to less than 2000% by weight.

Hygroscopic and water-absorbent fibers of the present invention generate heat by absorbing moisture and water. Since both the amount of moisture absorption and the amount of water absorption are large, the total calorific value when the absolutely dried sample is put in water is large.
Generates heat of 0 J / g or more.

The moisture absorbent and water absorbent fiber product of the present invention is a fiber product containing the moisture absorbent and water absorbent fiber of the present invention. Textile products include, for example, non-woven fabrics, knitted fabrics, futons, battings and spun yarns. The hygroscopic and water-absorbent fibers of the present invention are used in these textile products.
It is preferable that the content is at least wt%. This hygroscopic water-absorbent fiber exhibits twice or more hygroscopicity as compared with wool, which has the highest hygroscopicity among natural fibers. For example, 35 at 20 ° C and 65% relative humidity
% Or more hygroscopic. Therefore, for example, when 5% is contained in the synthetic fiber polyester having almost no hygroscopicity, the hygroscopicity is 7%, and the hygroscopicity is similar to that of the natural fiber cotton.

As a method for producing the above-mentioned non-woven fabric, for example, there is a method in which the above-mentioned hygroscopic and water-absorbent fibers are mixed and a web is produced by carding and crosslaying. As a method of bonding the web, there are a thermal method and a needling method.

For thermal bonding, generally, heat fusion fibers are mixed and used, or heat fusion powder,
For example, polyethylene powder may be dispersed and used.
Examples of commercially available heat-sealing fibers include, for example, "ES" (trade name) manufactured by Chisso Corp. using polypropylene for the core and polyethylene for the sheath, or polyethylene for the sheath manufactured by Kanebo Ltd., or Modified polyester, "bell combi" using polyester for the core, and the like are available.

For thermal bonding, 5 to 20% by weight of the heat-sealing fiber and / or the heat-sealing powder may be mixed. When it is less than 5% by weight, needle punching may be used together.

When carrying out the above-mentioned carding, it is preferable that the hygroscopic and water-absorbent fiber of the present invention having a small fiber strength is made of a thick single fiber, and the other fibers to be mixed are thinned.
A web can be formed by the thin fibers sinking under the needle of the card and wrapping around the thick fiber above the needle. By selecting the thickness of the single fibers of the fibers to be mixed in this way, it is possible to reduce the loss of the fibers when forming the web. The thickness of the hygroscopic and hygroscopic fiber having a low fiber strength is preferably 6 denier or more and 15 denier or less, and the fiber having a high fiber strength has a thickness of 2 denier or more, 5
Denier or less is preferred. Web uniformity is not very important, so a woolen roller card with one cylinder is fine. Roller cards are preferable to flat cards because of their higher denier. Further, it is preferable that the fiber length is 50 to 75 mm because fiber damage is small. In the same sense, it is preferable to shorten the fiber length of the fiber having a large thickness and a low fiber strength, which is contrary to the usual case.

Further, as another method for producing the above-mentioned hygroscopic and water-absorbent dry type nonwoven fabric, the air lay method can be used. In the case of thermal bonding, heat fusion fiber and /
Alternatively, 5 to 20% by weight of a binder made of heat fusion powder may be mixed. If the amount is less than 5% by weight, the bonding will be insufficient, and therefore it is necessary to support it with another non-woven fabric or paper for handling. By using this support, moisture-absorbing water-absorbent fibers or hygroscopic polymers can be self-bonded to each other by applying moisture without using heat-fusion fibers or heat-fusion powder. Therefore, in this case, the heat-sealing fibers and / or the heat-sealing powder can be used to prevent falling off.

In the case of the air laying method which does not use a card, the thickness of the hygroscopic water absorbent fiber having a low fiber strength is 6 denier or more, 1
5 denier or less is preferable because it is easily dispersed. The fiber length of the moisture absorbent and water absorbent fibers is preferably 4 to 15 mm in the same meaning. The other fibers used in this method preferably have properties similar to those of the main moisture-absorbing and water-absorbing fibers.

The moisture-absorbing and water-absorbing fiber of the present invention can be spun by a general spinning method, for example, short spinning, long spinning, woolen, semi-silver wool, wrap yarn, binding spinning and the like to produce a spun yarn. Since the hygroscopicity is large, it is preferable to sufficiently control the temperature and humidity, and although it varies depending on the blending ratio, even if the content of the hygroscopic water-absorbing fiber is less than 30% by weight, the spinning can be performed in the environment where the relative humidity is 60% or less. preferable. More preferably 55
% Or less. The blending ratio, the number of twists, the number of constituents, etc. are small in the fiber strength of the moisture-absorbing and water-absorbing fibers, so it is better to exclude the moisture-absorbing and water-absorbing fibers from the calculation and design them.

A general knitted fabric can be easily manufactured by using the above spun yarn. Moreover, a knitted fabric can be manufactured by twisting, knitting, and weaving. Furthermore, futon cotton or the like is mixed with the hygroscopic and water-absorbent fiber of the present invention by blow molding,
Can be used.

Further, the above fiber product can be imparted with its performance by mixing antibacterial and deodorant fibers or the like, or can be subjected to various processes by post-processing. Since the hygroscopic and water-absorbent fiber of the present invention also retains water absorbency, the above fiber product can also have the performance as a water-absorbing agent. Even after absorbing water, the fiber strength remains high enough to withstand home washing, so it can be washed with water and can be used repeatedly after washing.

Further, the hygroscopic and water-absorbent fiber of the present invention can be repeatedly absorbed and dehumidified. If the moisture absorption rate is less than 90%, the moisture absorption and dehumidification can be carried out very quickly. If the fiber product is in the form of a thin non-woven fabric, the equilibrium value is reached in about 15 minutes even without wind.

The moisture absorption / dehumidification rate of the textile product of the present invention can be appropriately adjusted by appropriately selecting the surface material of the textile product. That is, in order to increase the speed, the contact area with air and the air permeation speed may be increased. On the contrary, in order to reduce the size, the film may be covered with a non-moisture permeable film or the like, and an appropriate number of holes may be formed in the film to adjust the contact area with air and the air permeation rate.

The hygroscopic and water-absorbent fiber product of the present invention can also be used in combination with other materials having an auxiliary hygroscopic property. For example, there are natural fibers having high hygroscopicity, silk, wool, cotton, pulp and the like, water absorbing polymers, water absorbing fibers and silica gel. These materials can be used together by mixing or laminating.

The hygroscopic and water-absorbent fibers and the hygroscopic and water-absorbent fiber products of the present invention were placed in an artificial climate chamber where the moisture absorption rate was controlled to a predetermined temperature and humidity.
The difference between the absolute dry weights, which became constant with the hot air dryer, was divided by the absolute dry weights, and the percentage was obtained. The water absorption of ion-exchanged water was measured according to DIN53814 by the centrifugal dehydration method. The retention of the fiber morphology after water absorption was evaluated by placing the sample in a bag of polyester taffeta fabric, repeating home washing 5 times according to JIS, then opening the bag, and visually observing. The retention of the fiber morphology of the non-woven fabric and spun yarn was evaluated in the same manner.

[0032]

The hygroscopic and water-absorbent fiber of the present invention has a large amount of moisture absorption and a large amount of water absorption. Further, since the moisture absorption rate is high, the moisture absorption rate can be freely selected by selecting the covering material. Further, it can repeatedly absorb and dehumidify, and can be used as a humidity control agent. In addition to being hygroscopic, it also has water absorbency and can withstand washing with water. Moisture absorption,
Generates heat when absorbing water, and has a large calorific value. On the contrary, it absorbs heat when it is released and dried, and the amount of heat absorbed is large.

[0033]

【Example】

Example 1 Water absorption rate of physiological saline solution is 1300% by weight, 20 ° C., 65%
"Bell Oasis" with a moisture absorption rate of 44% by weight at relative humidity 9
Denier (hereinafter referred to as "d") 51 mm was heat-treated with a suction type hot air dryer while changing the temperature and the treatment time to promote crosslinking. The water absorption after heat treatment and the water absorption at 20 ° C. and 65% relative humidity were measured and are shown in Table 1. Test No. 1
The hygroscopic and water-absorbent fibers of Nos. 6 to 6 retained the fiber shape even after 5 times of home washing. In the reference example of 7, the fiber was cut into 3 mm or less after one home washing, and the fiber shape was not maintained.

Moisture Absorption The water-absorbent fiber of the present invention was gradually absorbed at 30 ° C. and 100% relative humidity for 170 hours. As a result, it reached saturation and the maximum moisture absorption reached 520% by weight. Test N
o. The hygroscopic and water-absorbent fibers of the present invention No. 3 of the present invention were dried to an absolute dry state, then put into ion-exchanged water at 20 ° C. and 0.9% physiological saline, and the calorific values were measured. The calorific values were 185 J / g and 145 J / g, which were very large values.

[0035]

[Table 1]

Example 2 No. 2 of Example 1. 3. Moisture-absorbing and water-absorbing fibers 9d, 6 of the present invention
A mixture of mm and pulp in a weight ratio of 1: 2 was continuously sprinkled by an air laying method on a paper having a basis weight of 15 g / m ² on a suction net so that the basis weight was 100 g / m ^2. Laminated. The unit weight was adjusted by continuously measuring the net speed and the supply amount. Next, a paper having a basis weight of 15 g / m ² was laminated on the second layer to form a three-layer structure, and the hygroscopic and water-absorbent fiber product of the present invention was manufactured. The moisture absorption rate of this non-woven fabric was 13.7% at 20 ° C. and 60% relative humidity, which was more than twice as high as that of pulp alone.

Example 3 No. 1 of Example 1 was used. 3. Moisture-absorbing and water-absorbing fibers 9d and 5 of the present invention
1 mm and polyethylene terephthalate fiber SD2d, 51 mm manufactured by Kanebo Co., Ltd. were mixed at a weight ratio of 1: 2, and short spinning was performed to produce No. 10 twin yarn of the moisture absorbent and water absorbent fiber product of the present invention. The moisture absorption rate of this yarn is 1 at 20 ° C and 60% relative humidity.
It exhibited a hygroscopicity of 2.8%, which is three times or more that of a polyester fiber and a cotton equivalent yarn.

Example 4 No. 1 of Example 1. 5, hygroscopic and water-absorbent fibers 9d of the present invention, 5
1 mm and polyethylene terephthalate fiber SD2d manufactured by Kanebo Ltd., 51 mm were mixed at a weight ratio of 1: 1 to produce polyethylene terephthalate filament FD manufactured by Kanebo Ltd.
Y75D / 24F was wound and lap spinning was performed to produce No. 20 single yarn of the moisture absorbent and water absorbent fiber product of the present invention. This yarn was knitted into a plain cloth using a 20 gauge circular knitting machine. The moisture absorption rate of this circular knitted fabric was 19.8% at 20 ° C. and 60% relative humidity, which was about 5 times as high as that of the knitted fabric of polyester fiber and cotton.

Claims (2)

[Claims] 1. A fibrous form is maintained even after absorbing water, and a moisture absorption rate at 20 ° C. and a relative humidity of 65% is 35% by weight or more.
A hygroscopic and water-absorbent fiber having a water absorption rate of 9% physiological saline of 800% by weight or more. 2. A fiber product containing 5% by weight or more of the hygroscopic and water-absorbent fiber according to claim 1.