JP2000160480A - Production of water-repellent processed cloth having moist absorption and desorption property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing water-repellent processed cloth having moist absorption and desorption property, excellent in hygroscopicity and moist desorption property and having water repellency too. SOLUTION: This water-repellent processed cloth having moist absorption and desorption property is produced by the after processing where cloth subjected to graft copolymerization with an acidic unsaturated monomer is treated with an alkali, followed by forming a polyion complex with an aqueous solution of a dialkylammonium salt to introduce hydrophobic groups onto the surface of the cloth and by the water repellent treatment. The water-repellent processed cloth has the water repellency of <=350 μN/cm surface tension, and has moist absorption and desorption property where fiber shows >=5 wt.% moisture content after being left for 60 min at 30 deg.C and 95% RH from bone dry condition and >=80% decreasing rate of moisture content after being left for 60 min at 25 deg.C and 40% RH from the condition at 30 deg.C and 95% RH.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a water-repellent, moisture-absorbing and desorbing work cloth which is excellent in moisture absorbency and moisture release and has water repellency.

[0002]

2. Description of the Related Art Synthetic fibers have excellent mechanical strength, chemical resistance, heat resistance and washing resistance, and are widely used in clothing and interior applications. In applications such as raincoats and sportswear, the function of preventing the penetration of water, such as rain, into clothes is required.In the comfort of clothing, the function of absorbing sweat generated by sweating from the skin and releasing moisture to the outside air is required. Can be In addition, as an industrial material, a wall cloth material having a humidity control function and an antifouling property is required. A function common to these fibers is a function having both water repellency and moisture absorption / release properties. Until now, to impart water repellency, advanced water repellency treatment was applied by coating with silicone or a fluoropolymer, and to impart moisture absorption, moisture absorption treatment was applied by coating a hydrophilic or water-absorbent resin. , Each has been administered alone.

[0003] Such water repellency and hygroscopicity are completely contradictory functions, and it has heretofore been considered difficult to produce fibers having both water repellency and hygroscopicity. Therefore, conventionally, as a method of imparting water repellency and moisture absorption / desorption properties to the fiber filament itself, the core is made of a hygroscopic polymer, and the sheath is made of a water repellent fiber and a water absorbent fiber. By using a core-sheath structure yarn made of an aqueous polymer, further, in the post-processing method of the woven fabric, by coating the water-absorbent resin on the surface of the woven fabric and the water-repellent resin on the back surface,
Attempts have been made to obtain textiles having water repellency and hygroscopicity.

[0004]

However, in such a method, the hygroscopicity is lower than that of natural cotton cloth, and the intended purpose is not sufficiently achieved. In particular, in the post-processing method, even if the surface of the cloth which has been subjected to the moisture absorption / desorption property is directly subjected to water repellency processing by a known method, the polarities are completely opposite, and good water repellency with good adhesion cannot be obtained. In addition, when a highly water-repellent treatment is applied and the fiber surface is thickly covered with a water-repellent resin, water repellency is exhibited, but the problem of extremely low moisture absorption / release properties remains. In view of the above, the emergence of a post-processing method having both functions of contradictory functions of water repellency and moisture absorption / release has been expected. Therefore, the present inventors have found a post-processing method having a high moisture absorption / desorption rate and having water repellency, and have reached the present invention.

[0005]

Means for Solving the Problems Water repellency is a chemical of the surface,
Water molecules can be easily diffused through the water-repellent layer and adsorbed on the internal moisture-absorbing layer due to the fact that they are derived from the physical structure and the moisture absorption / desorption properties are small due to the small molecular size of water vapor. Utilizing this fact, a post-processing method was found, which led to the present invention. Specifically, a woven fabric obtained by graft polymerization of an acidic unsaturated monomer is subjected to an alkali treatment to exhibit a moisture absorbing / releasing function. By making use of this functional group exhibiting moisture absorption / release function to form a polyion complex with a dialkylammonium salt, which is an ionic compound having a long-chain alkyl group, the hygroscopic hydrophilic surface becomes hydrophobic. Successfully reformed. By applying a water-repellent treatment to this hydrophobic surface,
Durable water repellency and moisture absorption / release properties could be obtained. By the above treatment, the woven fabric has a water repellency of 350 μN / cm or less in surface tension, and the woven fabric is kept at 30 ° C. and 95%
Moisture content after leaving for 60 minutes in an RH environment is 5% by weight or more, and 25 ° C, 40% from 30 ° C, 95% RH environment
The rate of decrease in the moisture content after standing for 60 minutes in an environment of RH is 8
It has become possible to produce a water-repellent, moisture-absorbing and desorbing work cloth having a moisture-absorbing property of 0% or more.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First,
The woven fabric applied to the present invention is not particularly limited as long as the graft polymerization of the acidic unsaturated monomer is possible, but is preferably a synthetic fiber of polyethylene, polypropylene, polyester, nylon, acrylonitrile, acetate, The form may be either woven or non-woven fabric.
Further, as the acidic unsaturated monomer imparting moisture absorption and desorption,
As long as radical polymerization is performed with an unsaturated monomer having an acidic group, acrylic acid, methacrylic acid, p-styrenesulfonic acid, or a mixture thereof is preferable.

The means for graft polymerization in the present invention may be any method as long as it generates radicals by radiation, ultraviolet rays, plasma, a catalyst, etc., and causes graft polymerization of an acidic unsaturated monomer. A method using radiation capable of generating radicals on various woven fabric substrates, particularly electron beam irradiation, is preferable. 10 to 50 electron beams on woven cloth
After irradiation with 0 kGy, the graft polymerization easily occurs in a pre-irradiation polymerization method of immersion in a solution of an acidic unsaturated monomer, and the amount of graft can be varied by controlling the polymerization time and the concentration of the acidic unsaturated monomer. Can be easily done. An electron beam is applied to the woven fabric impregnated with the acidic unsaturated monomer solution for 10 to 500 times.
Graft polymerization is also possible by the simultaneous irradiation method of kGy irradiation.

By subjecting the graft-polymerized woven fabric to an alkali treatment, the woven fabric becomes hydrophilic, and high moisture absorption / desorption and water absorption can be obtained. Alkaline treatment is 0.02 or more 2
The treatment may be performed within 30 minutes with an aqueous solution of ammonium hydroxide, lithium hydroxide, sodium hydroxide or potassium hydroxide below the specified amount. By this treatment, the woven fabric has a function of absorbing and releasing moisture in proportion to the graft amount, and the graft amount may be freely changed according to the application. However, the graft amount of the acidic group in the present invention is 1.5 to 8 meq. / G range.

Next, a method of imparting water repellency to the woven fabric having moisture absorption and desorption properties is provided by a processing method for imparting water repellency to the surface, such as a fluorine-based material containing silicone or perfluoroalkyl acrylate as a main component. Good coating with a water-repellent agent or plasma treatment using a fluorine-based gas. However, even if the moisture-absorbing / desorbing woven fabric is directly processed with a fluorine-based water-repellent agent containing silicone or perfluoroalkyl acrylate as a main component, it does not react with the moisture-absorbing / desorbing functional group and has good adhesion. Water repellency cannot be imparted. Also, when completely covered with a water repellent agent, a phenomenon occurs in which water repellency is exhibited, but moisture absorption / release properties are extremely reduced.

Accordingly, the present inventors have studied the introduction of an alkyl layer by a method of ion-bonding with a functional group which exhibits moisture absorption / release properties. As a method for introducing the alkyl layer onto the surface of the moisture-absorbing and desorbing processed fiber, the formation of a polyion complex of an acidic group, which is a functional group of the graft chain, and a quaternary ammonium salt was examined, and a quaternary compound having various long-chain alkyl groups was examined. Using an ammonium salt type compound, a compound which is made to react in an aqueous solution and has a large decrease in the wettability of the fiber surface and becomes hydrophobic was examined. As a result, the two-chain C12-
A dialkyldimethylammonium salt of 18 was found to be good. Generally, an alkyl ammonium salt is ionically bonded to an acidic group of a graft chain to form a polyon complex. However, as compared with a single-chain C12-18 alkyltrimethylammonium salt, a two-chain C12-1 alkyltrimethylammonium salt is used.
The dialkyldimethylammonium salt of No. 8 has a strong property of molecular orientation so that it has an alkyl group on the air interface, that is, a structure having a hydrophilic group on the surface, so that the surface is hydrophobic and hardly wet with water. The ion binding portion will exhibit hydrophilic moisture absorption / release properties. In particular,
0.1 g of dioctadecyldimethylammonium bromide
In a 5% aqueous solution, apply a moisture-absorbing / desorbing work cloth at 40-70 ° C for 1-1.
By performing the treatment for 5 minutes, the wettability of the surface of the woven fabric greatly changes, and the surface state having good water wettability before the treatment becomes hydrophobic by this treatment and becomes less wettable with water. Also, at this time, the amount of the polyalkyl complex of the dialkyldimethylammonium salt can be controlled by changing the treatment time, and the amount of formation is required to be 5% or more in terms of the rate of weight increase of the treated sample after drying. Is 5 to 100%
It is.

The water-repellent treatment after the introduction of the alkyl layer on the surface as described above may be performed by a known method. As a method for obtaining high water-repellency, a fluorine-based water-repellent containing perfluoroalkyl acrylate as a main component is used. Water repellency can be easily obtained by coating a processing agent or performing plasma treatment using tetrafluoromethylene gas. At this time, the water repellency is determined by measuring the surface tension of the sample from the wettability of the liquid, and if the value is greater than the surface tension of water, 720 μN / cm, the sample is wetted by water. If it is lower, it is difficult to get wet with water. To develop good water repellency, this surface tension should be at least 350 μN /
cm or less.

[0012]

EXAMPLES (Example 1) 250k on polypropylene cloth
Radiation was generated by irradiating 100 kGy with an irradiation dose using an electron beam irradiation apparatus having an acceleration voltage of V, and graft polymerization was performed by immersing the irradiated fibers in a 20% aqueous solution of acrylic acid at 40 ° C. Set the immersion time to 0.
By changing to 5, 1.4, and 2.5 hours, the graft ratio was 18% (Example 1-1) and 52% (Example 1-).
2) A sample cloth of 120% (Example 1-3) was obtained. This graft cloth is placed in a 0.1N aqueous sodium hydroxide solution at 60 ° C.
Treated for 20 minutes. This alkali-treated cloth is added to a 0.5% aqueous solution of dioctadecyldimethylammonium bromide for 60 hours.
After immersion at 5 ° C. for 5 minutes and drying, using an external electrode type glow discharge plasma processing apparatus, tetrafluoromethylene gas was introduced to a pressure of 0.25 torr,
A plasma treatment was performed at an output of 100 W for 15 minutes to obtain a water-repellent, moisture-absorbing and desorbing work cloth.

[0013]

(Example 2) A 20% aqueous solution was prepared so that the molar ratio of acrylic acid and styrene sulfonic acid was 3: 1. Graft polymerization was carried out on a polypropylene cloth in the same manner as in Example 1, and the graft ratio was 43%. Sample was obtained. After the alkali treatment in the same manner as in Example 1, a 0.5% aqueous solution of dioctadecyldimethylammonium bromide was treated at 60 ° C., the immersion time was changed to 1 minute and 15 minutes, and the weight of the dried sample after the polyion complex was formed. 6% increase (Example 2)
-1), a sample cloth of 78% (Example 2-2) was obtained.
Then, a plasma treatment was performed in the same manner as in Example 1 to obtain a water-repellent, moisture-absorbing and desorbing work cloth.

[0014]

Example 3 A 20% aqueous solution was prepared so that the molar ratio of acrylic acid and styrene sulfonic acid was 3: 1. Graft polymerization was carried out on a polypropylene cloth in the same manner as in Example 1, and the graft ratio was 43%. Sample was obtained. After alkali treatment in the same manner as in Example 1, and further treatment with dioctadecyldimethylammonium bromide, NK guard NDN (Nichika Chemical Co., Ltd.), a perfluoroalkyl acrylate-based water repellent, was used. % Aqueous solution was padded and dried to obtain a water-repellent, moisture-absorbing and releasing fabric.

[0015]

(Example 4) A nylon cloth was impregnated with a 10% aqueous solution of acrylic acid in the same weight as the weight of the substrate and dried.
Irradiation was carried out at an irradiation dose of 100 kGy using an electron beam irradiation device having an acceleration voltage of 250 kV to obtain a nylon cloth graft-polymerized with acrylic acid. This graft cloth is placed in a 0.05 N aqueous solution of sodium hydroxide at 40 ° C. 10
Minutes. The alkali-treated cloth is immersed in a 0.5% dioctadecyldimethylammonium bromide aqueous solution for 5 minutes, dried, and then, using an external electrode type glow discharge plasma processing apparatus, the pressure of tetrafluoromethylene gas is reduced to 0.25 torr. And subjected to a plasma treatment at an output of 100 W for 15 minutes to obtain a water-repellent, moisture-absorbing and desorbing work cloth.

[0016]

[Comparative Example] (Comparative Example 1) Example 1 on polypropylene cloth
A sample having a graft ratio of 52% was obtained by the same graft polymerization as described above. Next, a cloth treated with alkali in the same manner as in Example 1 was obtained. The characteristics of the obtained cloth were examined, and the results are shown in Table 1.

[0017]

[Comparative Example] (Comparative Example 2) Example 1 on polypropylene cloth
A sample having a graft ratio of 52% was obtained by the same graft polymerization as described above. Next, after alkali treatment as in Example 1,
A cloth treated with a 0.5% aqueous solution of dioctadecyldimethylammonium bromide was obtained. The characteristics of the obtained cloth were examined, and the results are shown in Table 1.

[0018]

[Comparative Example] (Comparative Example 3) Example 1 on polypropylene cloth
A sample having a graft ratio of 52% was obtained by the same graft polymerization as described above. Next, the cloth which had been subjected to the alkali treatment in the same manner as in Example 1 was dried, and then, using an external electrode type glow discharge plasma treatment apparatus, 0.25 t of tetrafluoromethylene gas was used.
orr pressure and 15W at 100W output
Plasma treatment was performed for minutes. Check the characteristics of the obtained cloth,
The results are shown in Table 1.

[0019]

Comparative Example 4 Comparative Example 4 The same graft polymerization as in Example 3 was performed on a nylon cloth to obtain a sample having a graft amount of 16%. After drying the alkali-treated cloth, tetrafluoromethane gas was introduced to a pressure of 0.25 torr using an external electrode type glow discharge plasma processing apparatus, and plasma processing was performed at an output of 100 W for 15 minutes.
The characteristics of the obtained cloth were examined, and the results are shown in Table 1.

The reaction amounts and properties of the work cloths of Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated by the following measuring methods. (1) Graft ratio The graft ratio of the acidic unsaturated monomer is determined by the dry weight (W) before the reaction.
It was calculated as follows from 1) and the dry weight (W2) after the graft reaction. Graft ratio = (W2−W1) / W1 × 100 (%) (2) Graft amount The amount of the acidic unsaturated monomer introduced into the cloth was defined as the graft amount, and the graft sample 1 was determined from the weight change before and after the treatment and the elemental analysis.
The amount of acidic groups per g was expressed in mmol. (3) PIC amount The dry weight before treatment with an aqueous solution of dioctadecyldimethylammonium bromide is measured (W3). The dry weight after the treatment was measured (W4), and the rate of weight increase after forming the polyion complex was calculated as the PIC amount by the following equation. PIC amount = (W4−W3) / W3 × 100 (%)

(4) Moisture content at the time of moisture absorption The moisture content at the time of moisture absorption is determined by drying a sample work cloth at 50 ° C. for 5 hours using a vacuum dryer (W5). Next, the sample was placed at 30 ° C.
The sample is put in a thermo-hygrostat at 95% RH for 60 minutes, and the weight of the absorbed sample is measured (W6). From the above measurement results, it was calculated by the following equation. Moisture content at the time of moisture absorption (Abs) = (W6-W5) / W5 × 10
0 (%) (5) Moisture release rate The moisture content at the time of moisture release is 6% in a thermo-hygrostat at 30 ° C. and 95% RH.
The sample work cloth left for 0 minutes is taken out and its weight is measured (W7). The sample is left in a thermo-hygrostat at 25 ° C. and 40% RH for 60 minutes, and its weight is measured (W8). From the above measurement results, the moisture content at the time of moisture release was calculated and further divided by the moisture absorption moisture content (Ab) to calculate the moisture release rate as in the following equation. Moisture content at the time of moisture release (Des) = (W8−W7) / W7 × 10
0 Moisture release rate = (Des) / (Abs) × 100 (%)

(6) Water repellency Water repellency is determined by determining whether a wetness indicator reagent of Wako Pure Chemical Industries, Ltd. or an organic solvent having a clear surface tension is dropped onto a surface of a work cloth by dropping 20 microliters of water to determine whether or not the material is wet. Was determined, and the surface tension (μN / cm) of the liquid that did not spread was used as an index of water repellency.

With respect to the cloths obtained in Examples 1 to 4 and Comparative Examples 1 to 3, the results of measurement of the moisture content at the time of moisture absorption, the moisture release rate, the water repellency and the like are shown in Table 1.

[0024]

[Table 1]

[0025]

According to the present invention, it is possible to manufacture a water-repellent and moisture-absorbing processed cloth having both high water-absorbing and moisture-releasing properties and water repellency contradicting the property by a post-processing method of a woven fabric. Thus, it can be applied as a material for industrial materials such as clothing and interiors.

Claims (4)

[Claims] 1. A woven fabric obtained by graft polymerization of an acidic unsaturated monomer is subjected to an alkali treatment, and then a polyion complex is formed with an aqueous solution of a dialkylammonium salt to introduce a hydrophobic group to the surface and then subjected to a water-repellent treatment. A method for producing a water-repellent, moisture-absorbing and moisture-absorbing work cloth, comprising the steps of: 2. The acidic unsaturated monomer is acrylic acid, methacrylic acid or styrenesulfonic acid or a mixture thereof, and the graft amount of the acidic group on the work cloth is 1.5 to 8 meq.
The method for producing a water-repellent, moisture-absorbing and desorbing processed cloth according to claim 1, wherein 3. The method according to claim 1, wherein the dialkylammonium salt is a compound represented by the following general formula 1, and the weight increase rate after forming a polyion complex is 5 to 100%.
A method for producing the water-repellent, moisture-absorbing and desorbing processed cloth described in the above. Embedded image 4. The water-repellent and moisture-absorbent work cloth produced by the method according to claim 1, which has a water repellency of 350 μN / cm or less in surface tension, and changes the work cloth from an absolutely dry state to 30 μN / cm.
The moisture content after leaving for 60 minutes in an environment of 30 ° C. and 95% RH is 5% by weight or more and 25% in an environment of 30 ° C. and 95% RH.
2. The water-repellent moisture-absorbing / desorbing fabric according to claim 1, wherein the fabric has a moisture-absorbing / desorbing property in which the percentage of decrease in moisture after being left for 60 minutes in an environment of 40 [deg.] C. and 40% RH is 80% or more. Law.