JP2019167644A - Manufacturing method of decolored elastic substrate - Google Patents

Abstract

To provide a manufacturing method of a decolored elastic substrate capable of decoloring a color of an elastic substrate while suppressing reduction of shrinkage degree of the elastic substrate by improving a decolorant.SOLUTION: There is provided a manufacturing method of a decolored elastic substrate including a process for contacting an elastic substrate containing colored polyurethane fibers and liquid containing chlorine dioxide. The colored substrate is preferably a sewn cloth product. Retention rate of elasticity of the decolored elastic substrate is preferably 60% or more. Retention rate of tensile strength of the decolored elastic substrate is preferably 60% or more. Color difference between the elastic substrate before decoloration and the elastic substrate after decoloration (ΔE*ab) is preferably 5 or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a decolored stretchable fabric.

An elastic fabric containing polyurethane fibers may be used as a fabric used for clothes and the like. In particular, in a slim garment, a sports garment, an accessory such as a supporter, or an underwear, a stretchable fabric may be used for the purpose of improving comfort and easiness of movement.

On the other hand, decoloring of stretchable fabrics with a solution containing hypochlorous acid is also performed for the purpose of giving a texture that has changed over time due to use or adjusting the hue.

For example, Patent Document 1 describes a stretchable cotton fabric having an elastic yarn containing polyurethane having a specific molecular structure and a dyed cotton yarn. It is said that this fabric was treated with sodium hypochlorite for the first time to provide a decolored cotton fabric having stretchability.

Patent Document 2 describes a polyurethane urea polymer and a polyurethane elastic fiber formed from the polyurethane polymer. This fiber is mixed with an oxide of Mg, Zn, or Al. This elastic fiber is said to have resistance to sodium hypochlorite.

Patent Document 3 describes a stretchable fabric containing an ethylene / alpha-olefin interpolymer. This dough is said to show excellent chlorine resistance.

Japanese Patent Laid-Open No. 04-185737 JP 2002-339166 A Special table 2010-511801 gazette

The methods of Patent Document 1 to Patent Document 3 all improve the fiber itself constituting the fabric. For this reason, it is composed of general polyurethane fibers that do not contain specific substances such as polyurea and metal oxides, or general polyurethane fibers that are manufactured using raw materials other than raw materials that satisfy predetermined parameters. As for the fabrics, there was a problem that, when decolorized with sodium hypochlorite, the elastic modulus of the stretchable fabric was significantly impaired. For example, when contracting decolorization processing of stretchable fabrics from a plurality of manufacturers, the configuration of the stretchable fabrics to be brought in varies, and there are cases where it is difficult to respond.

An object of the present invention is to provide a method for producing a decoloring stretchable fabric capable of decoloring the color of the stretchable fabric while suppressing a decrease in the stretch rate of the stretchable fabric by improving the decolorizing agent. To do.

The above problem is solved by a method for producing a decoloring stretchable fabric comprising a step of bringing a stretchable fabric containing dyed polyurethane fibers into contact with a liquid containing chlorine dioxide.

In the above production method, the dyed fabric is preferably a sewn fabric product. Moreover, it is preferable that the retention rate of the elastic modulus of a decoloring stretchable fabric is 60% or more. Moreover, it is preferable that the retention rate of the tensile strength of a decoloring stretchable fabric is 60% or more. The color difference (ΔE * ab) between the stretchable fabric before decolorization and the stretchable fabric after decolorization is preferably 5 or more.

ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the manufacturing method of the decoloring elastic fabric which can decolor the color of an elastic fabric, suppressing the fall of the expansion rate of an elastic fabric.

It is a graph which shows the relationship between the density | concentration of chlorine dioxide aqueous solution or sodium hypochlorite aqueous solution (pH5), and (DELTA) E * ab. It is a graph which shows the relationship between the color difference (DELTA) E * ab and the elasticity modulus E at the time of processing with a chlorine dioxide solution or sodium hypochlorite aqueous solution (pH5). When treated with chlorine dioxide solution, or sodium hypochlorite solution (pH 5), and the color difference Delta] E * ab, is a graph showing the relationship between the tensile strength T _B. When treated with chlorine dioxide solution, or sodium hypochlorite solution (pH 5), and the color difference Delta] E * ab, is a graph showing the relationship between the elongation at break E _B.

Hereinafter, modes for carrying out the present invention will be described.

The present invention is a method for producing a decolorized stretchable fabric comprising a step of contacting a stretchable fabric containing dyed polyurethane fibers (hereinafter simply referred to as a stretchable fabric) and a liquid containing chlorine dioxide.

The method for bringing the stretchable fabric containing polyurethane fibers into contact with the liquid containing chlorine dioxide is not particularly limited. For example, the liquid containing chlorine dioxide may be impregnated by spraying on the stretchable fabric, or the stretchable fabric may be immersed in a liquid containing chlorine dioxide. When a large amount of stretchable fabric is decolorized, it is preferably carried out by dipping. Further, as will be described later, partial discoloration may be performed when used processing is performed. In such a case, it is preferable to carry out by spraying.

The stretchable fabric may have any configuration as long as the fabric is stretched by polyurethane. For example, weaving using spanned yarn containing polyurethane fiber in at least one of warp and weft, multifilament yarn containing polyurethane fiber, monofilament yarn containing polyurethane fiber, or covered yarn containing polyurethane fiber Cloth. The covered yarn should just contain a polyurethane fiber, and the polyurethane fiber should just be used for either a core yarn or a wound yarn. The fabric may be a woven fabric containing polyurethane as described above, or may be a knitted fabric containing polyurethane.

The stretchable fabric to be contacted with the liquid containing chlorine dioxide may be, for example, an unsewn fabric, that is, a raw fabric or a sewn fabric product. Examples of the cloth products include upper garments, lower garments, sports clothes, supporters such as waist belts and wristbands, bags using cloth, shoes using cloth, and the like. As will be described later, when second-hand processing is performed on a product such as denim pants, decoloring processing is performed on a portion that is easily exposed to friction by use. For this reason, when performing a used process, it is preferable to perform a decoloring process in the state of the sewn product rather than in the state of the fabric.

Denim fabric is particularly suitable as the stretchable fabric to be contacted with the liquid containing chlorine dioxide. For example, in the case of a denim fabric such as denim pants or a denim product, the color of the denim fabric is faded and a unique texture is born. In order to reproduce this texture, there is even a process of deliberately decoloring new denim pants, denim jackets, denim shirts and the like. According to the method of this embodiment, the dye of the fabric can be decolorized at any strength from small to large without degrading the strength and elasticity of the stretch fabric. For this reason, it is possible to carry out second-hand processing on elastic denim fabrics and denim products containing polyurethane fibers without significantly impairing elasticity and strength.

The polyurethane constituting the polyurethane fiber may have any elasticity so long as it can be spun. For example, a polyurethane fiber molecule that is commercially available for clothing includes a hard segment and a soft segment, and has an intermediate property between plastic and rubber. For this reason, it can be spun by melt spinning or the like, and has elasticity. Although the resistance to chlorine differs depending on the composition and molecular structure of the polyurethane fiber, it can be used even if it has high resistance, and can also be used that has low resistance.

The liquid containing chlorine dioxide can be obtained, for example, by passing a chlorine dioxide gas through water. For example, it can be obtained by adjusting the pH of the aqueous sodium chlorite solution. When using a sodium chlorite aqueous solution, the pH of the aqueous solution is preferably 7 or less, and preferably 6 or less. The lower limit of the pH of the aqueous solution is preferably 3 or more, and more preferably 4 or more.

Examples of the dye that imparts color to the stretchable fabric include reactive dyes, direct dyes, and dyes such as sulfur dyes and vat dyes.

The density | concentration of the chlorine dioxide contained in a decoloring liquid can be changed according to desired decoloring intensity | strength. If descaling is desired, the chlorine dioxide concentration should be increased. When desiring for weak color removal, the concentration of chlorine dioxide may be reduced. If the concentration of chlorine dioxide is excessively increased, the effect of decolorization is saturated. For this reason, the concentration of chlorine dioxide is preferably 1000 mg / L or less, more preferably 800 mg / L or less, and even more preferably 500 mg / L or less. The lower limit of the concentration of chlorine dioxide is preferably greater than 0 mg / L, more preferably greater than 5 mg / L, and even more preferably 10 mg / L or more.

The manufactured decolorized stretchable fabric has a color difference ΔE * ab before decolorization and after decolorization of preferably 5 or more, and more preferably 10 or more. The upper limit of the color difference ΔE * ab is not particularly limited, but is preferably 100 or less. The retention rate of the elastic modulus before and after decolorization of the decolorized stretchable fabric to be produced is preferably 60% or more, preferably 70% or more, and more preferably 75% or more. . The upper limit of the elastic modulus retention rate is not limited to good, but is preferably less than 100%. It is preferable that the retention ratio of the tensile strength of the decolorized stretchable fabric to be produced is also the same as the above range.

Examples of the present invention will be described below. The following examples are merely examples, and the present invention is not limited thereto.

A chlorine dioxide aqueous solution of each concentration was prepared by the following method, and the denim fabric dyed with the indigo dye was decolorized to evaluate the degree of decolorization.

[Preparation of aqueous chlorine dioxide solution]
4% potassium peroxodisulfate aqueous solution _{(K 2 S 2 O 8)} 35mL and 16% sodium chlorite (NaClO ₂₎ by flowing a nitrogen gas to a mixed solution of an aqueous solution 13 mL, to generate chlorine dioxide gas (ClO ₂₎ It was. The generated chlorine dioxide gas was passed through distilled water followed by a saturated aqueous sodium chlorite solution (NaClO ₂ ) and then dissolved in cooled distilled water to prepare an aqueous chlorine dioxide solution.

The chlorine dioxide concentration of the prepared aqueous chlorine dioxide solution was measured using a digital residual chlorine tester (DCT-05) manufactured by Takumina Co., Ltd. and diluted with distilled water to give 50 mg / L, 100 mg / L, 200 mg / L, or 400 mg / L was prepared.
[Preparation of aqueous sodium hypochlorite solution]
Effective chlorine concentration of commercially available sodium hypochlorite (NaClO) aqueous solution was measured using a digital residual chlorine tester (DCT-05) manufactured by Takumina Co., Ltd. and diluted with 0.2M phosphate buffer at pH 5 to be effective. The chlorine concentration was adjusted to 500 mg / L, 1000 mg / L, 1500 mg / L, or 2000 mg / L. Similarly, an aqueous solution of sodium hypochlorite having an effective chlorine concentration of 500 mg / L, 1000 mg / L, 1500 mg / L, or 2000 mg / L diluted with 0.2 M phosphate buffer having a pH of 12 was prepared. The hypochlorous acid (HClO) concentration was calculated from the effective chlorine concentration and pH, assuming that the dissociation constant pKa of hypochlorous acid was 7.5.

[Test cloth simulating denim fabric]
A 100% cotton plain weave structure dyed with indigo dye was cut into 30 mm × 30 mm to prepare a plurality of test cloths. Place the test cloth one by one in the container containing 50 mL of each concentration of chlorine dioxide aqueous solution or each pH and each concentration of sodium hypochlorite aqueous solution prepared above, and keep it still at 23 ° C for 2 hours under light shielding. I put it. After immersion, each test cloth was immersed in hypo (sodium thiosulfate) to remove chlorine dioxide, rinsed thoroughly with running water, and air-dried.

[Hue by decolorization]
For each of the above-mentioned concentrations of chlorine dioxide aqueous solution, test cloth decolorized with sodium hypochlorite at each concentration set to pH 5, and each test cloth before decolorization treatment, an image spectrophotometric colorimeter (COLOR manufactured by Kurabo Industries Co., Ltd.) / 7s), the hue was measured in the L * a * b color system, and the color difference ΔE * ab before and after decoloring was calculated by the following equation. FIG. 1 shows the relationship between the concentration of a chlorine dioxide aqueous solution or a sodium hypochlorite aqueous solution and ΔE * ab. In FIG. 1, a solid line indicates a value when a chlorine dioxide aqueous solution is used, and a broken line indicates a value when a sodium hypochlorite aqueous solution is used (the same applies to FIGS. 2 to 4 below).
[Formula 1]
ΔE * ab = {(ΔL *) ² + (Δa *) ² + (Δb *) ² } ^1/2
However, it is (DELTA) L * = L2-L1, (DELTA) a * = a2-a1, (DELTA) b * = b2-b1, L2, a2, or b2 is a value after decoloring, L1, a1, or b1 is before decoloring Is the value of

As is apparent from FIG. 1, ΔE * ab increased with increasing ClO ₂ or HClO concentration. ClO ₂ showed a decolorizing effect at a lower concentration compared to HClO.

Next, the physical properties of the polyurethane fiber treated with the aqueous chlorine dioxide solution and the polyurethane fiber treated with the hypochlorous acid aqueous solution were evaluated. The items of physical property evaluation are elastic modulus, tensile strength, and elongation at break.

[Evaluation of elastic modulus]
The elastic modulus was evaluated using a commercially available regular spandex yarn which is not chlorine-resistant grade. The spandex yarn used is a monofilament yarn and its fineness is 70 denier. The spandex yarn was wound so as not to overlap a cylindrical silicon tube having an outer diameter of 10 mm. The silicon tube was used as a jig to prevent the yarn from tangling during the test.

50 ml / L, 100 mg / L, 200 mg / L, or 400 mg / L of a chlorine dioxide aqueous solution having a concentration of 50 mg / L prepared by the above method, or a pH 5 and effective chlorine prepared by the above method; It was immersed in 50 ml of an aqueous sodium hypochlorite solution having a concentration of 500 mg / L or pH 12 and an effective chlorine concentration of 500 mg / L. The immersion conditions were 23 ° C., 2 hours, and a light shielding state. After immersion, the silicon tube wound with spandex yarn was immersed in hypo (sodium thiosulfate). Thereafter, the silicon tube around which the spandex yarn was wound with running water was sufficiently rinsed with running water and air-dried.

Each air-dried spandex yarn had a length of about 50 mm in a wound state. One end of each spandex yarn was fixed, and a weight F was fixed to the other end and suspended, and a load F was applied. The weight of the weight was changed so that the load F was 1 mN, 2 mN, 3 mN, 4 mN, and 5 mN. The length L of each spandex yarn when a load of 1 to 5 mN was applied was measured, and the relationship between the load F and the spandex yarn length was plotted in a graph. The relationship between the load F and the length L was linearly approximated. Based on the graph, the length L0 of the spandex yarn when the load F was zero was extrapolated.

Subsequently, the elongation ratio ε at each load value was determined by ε = (L−L0) / L0. Then, the slope of the load F with respect to the elongation ratio ε was divided by the fineness (tex) of the spandex yarn to obtain the elastic modulus E = (dF / dε) / tex (unit: mN / tex) of the spandex yarn. Spandex yarn treated with various concentrations of chlorine dioxide aqueous solution, spandex yarn treated with sodium hypochlorite aqueous solution at each pH, or untreated spandex yarn not immersed in chlorine dioxide aqueous solution or sodium hypochlorite aqueous solution Table 1 below shows the elastic modulus E and the elastic modulus retention for (blank). The retention rate was calculated by the following formula.
[Formula 2]
Retention rate (%) = elastic modulus E of spandex yarn immersed in aqueous chlorine dioxide solution of each concentration or aqueous sodium hypochlorite solution of each concentration ÷ elastic modulus E × 100 of blank spandex yarn

[Evaluation of tensile strength and elongation at break]
Spandex yarn treated with each concentration of chlorine dioxide aqueous solution, spandex yarn treated with sodium hypochlorite aqueous solution at each pH, or untreated not immersed in chlorine dioxide aqueous solution or sodium hypochlorite aqueous solution The spandex yarn (blank) was stretched by applying a load of 1 mN, and fixed to the pattern paper so that the length of the yarn was 50 mm. After fixing both ends of each spandex yarn with an air chuck of a universal material testing machine (AG-100kNXplus manufactured by Shimadzu Corporation), the pattern paper was cut. The pattern paper was used as a jig for keeping the yarn length constant.

Each spandex yarn was subjected to a tensile test by applying a load at a tensile speed of 500 mm / min. Aqueous solution of chlorine dioxide for each concentration of sodium hypochlorite solution at each pH, or tensile strength at the time of immersion in water T _{B (Unit:} mN / tex): Table below and the tensile strength retention of (in%) It was shown in 2. Tensile strength T _B and its retention rate was calculated by the following equation. Further, the following is the breaking elongation ratio E _B (unit:%) and the breaking elongation retention ratio (unit:%) when immersed in each concentration of chlorine dioxide aqueous solution, sodium hypochlorite aqueous solution at each pH, or water. Table 3 shows. Elongation at break E _B and retention was calculated by the following equation.
[Formula 3]
T _B = strength at break (mN) ÷ fineness (tex)
[Formula 4]
E _B = (length of spandex yarn at break−initial length of spandex yarn) ÷ initial length of spandex yarn × 100

The retention rate of tensile strength and the retention rate of elongation at break are determined by the following equations.
[Formula 5]
Tensile strength retention (%) = tensile strength T _B × 100 of spandex yarn tensile strength T _B ÷ blank spandex yarn was immersed in a sodium hypochlorite aqueous solution of chlorine dioxide solution or the concentration of each concentration
[Formula 6]
Breaking elongation retention ratio (%) = Elongation at break E _B of spandex yarn immersed in each concentration of chlorine dioxide aqueous solution or each concentration of sodium hypochlorite aqueous solution E _B ÷ Elongation at break E _B × 100 of blank spandex yarn

For each spandex yarn treated with the chlorine dioxide solution at each concentration determined above and the spandex yarn treated with the 500 mg / L aqueous sodium hypochlorite solution (pH 5) determined above, the color difference ΔE * ab and the elastic modulus E The relationship is shown as a graph in FIG. Further, the respective spandex yarn, showing a color difference Delta] E * ab, the relationship between the tensile strength T _B graphically in Figure 3. Further, the respective spandex yarn, showing a color difference Delta] E * ab, the relationship between the elongation at break E _B graphically in Figure 4.

As apparent from FIGS. 2 to 4, when the treatment is performed using an aqueous sodium hypochlorite solution having a pH of 5, the mechanical properties of the spandex yarn are significantly reduced under the condition that the decolorization of the indigo dye becomes large. It was found that decolorization was possible only within the specified color difference range. On the other hand, in the case of an aqueous chlorine dioxide solution, it was found that the mechanical properties were moderately lowered even under conditions where decolorization was large, and the indigo dye could be decolored without significantly impairing the tensile strength and stretchability of the spandex yarn. .

[Other dyes]
Next, whether or not decolorization ability was observed was evaluated for the fabric dyed with a dye other than the indigo dye by determining the color difference ΔE * ab between the fabric before and after the decolorization treatment.

As the dough, the following three kinds of dough were prepared.
[Fabric 1]
100% cotton twill fabric dyed with reactive dye. Reactive dyes include Sumifix (registered trademark) HF Yellow 3R (0.3% OWF), HF Scarlet 2G (0.3% OWF), and HF Blue BG manufactured by Chemtex Co., Ltd. A dye liquor mixed with (0.4% OW) was used.

[Fabric 2]
100% cotton plain woven fabric dyed with direct dye. As direct dyes, Kayaru (registered trademark) Yellow RL (0.3% OWF), Red BWS (0.3% OWF), Blue CGL (manufactured by Nippon Kayaku Co., Ltd.) A dye liquor mixed with 0.4% OW) was used.

[Fabric 3]
100% cotton plain woven fabric dyed with sulfur dye. As the sulfur dye, Asathiosol (registered trademark) Dark Blue S-2R (0.4% OW) manufactured by Asahi Chemical Industry Co., Ltd. and Brilliant Green S-GO (1.6% OW) are prepared. ) Was used.

[Fabric 4]
This is a twill woven fabric of 98% cotton and 2% polyurethane, rope-dyed with indigo dye. The warp is a cotton yarn dyed with an indigo dye, and the weft is a covered yarn in which a cotton yarn is wound around a polyurethane yarn.

The above fabrics 1 to 4 were immersed in a 40 mg / L chlorine dioxide aqueous solution obtained by the above-described method for 20 minutes, and the color difference ΔE * ab before and after immersion was evaluated. The color difference ΔE * ab was determined by the same method as described above.

As a result, for fabric 1, ΔE * ab was 29.23. For fabric 2, ΔE * ab was 29.29. For fabric 3, ΔE * ab was 15.91. For fabric 4, ΔE * ab was 15.99.

As is clear from this, it was confirmed that chlorine dioxide exhibits a decoloring effect on various dyes.

[Sensitive evaluation]
Next, the sensitivity evaluation was performed by the following method about the change of the physical property of the denim fabric by contact with chlorine dioxide. A twill denim fabric (polyurethane fiber 5% by mass) is a cotton yarn dyed with an indigo dye and an undyed covered yarn in which the weft is wound around a spandex yarn. The concentration of chlorine dioxide is 400 mg. It was immersed for 90 minutes at 20 ° C. in a solution adjusted to be / L. Then, soaping, rinsing, and hot air drying were performed. By pulling this denim fabric by hand, it was confirmed by a sensitive evaluation that the elasticity and strength were not impaired.As a result, both the elasticity and strength were kept healthy and were not inferior to the fabric before treatment. It was.

[Chlorine dioxide source]
Next, the supply source of chlorine dioxide was examined.

Sodium chlorite (NaClO ₂ ) reagent was dissolved in 0.3 M phosphate buffer at pH 5 to prepare 5 mM, 10 mM, and 100 mM NaClO ₂ aqueous solutions. The concentration of chlorous acid and chlorine dioxide measured using a digital residual chlorine tester (DCT-05) manufactured by Takumina Co., Ltd. was 230 mg / L and 0.1 mg / L with a 5 mM NaClO ₂ aqueous solution, and 10 mM NaClO _2. It was 390 mg / L and 0.1 mg / L in the aqueous solution, and 4700 mg / L and 3.1 mg / L in the 100 mM NaClO ₂ aqueous solution.

A sodium chlorite (NaClO ₂ ) reagent was dissolved in distilled water to prepare a 100 mM aqueous chlorite solution. The chlorous acid concentration and the chlorine dioxide concentration measured by the above tester were 4400 mg / L and 0.2 mg / L, respectively. The pH was 11.

A test cloth of 30 mm × 30 mm dyed with the same indigo dye as described above was placed in a container containing 50 mL of an aqueous solution of chlorous acid and allowed to stand at 23 ° C. for 2 hours under light shielding. After soaking, the cotton cloth was dipped in hypo (sodium thiosulfate), rinsed thoroughly with running water, and air-dried. For each test cloth, the color difference ΔE * ab before and after the decolorization treatment was determined. The color differences ΔE * ab of the cotton fabric soaked in 5 mM, 10 mM, 100 mM (pH 5), and 100 mM (pH 11) aqueous chlorous acid were 1.3, 1.2, 35.7, and 1.4, respectively. From this, when using sodium chlorite as a supply source of chlorine dioxide, it turned out that it is desirable to make pH of aqueous solution into 7 or less.

Claims (5)

A method for producing a decolorized stretchable fabric, comprising a step of bringing a stretchable fabric containing a dyed polyurethane fiber into contact with a liquid containing chlorine dioxide. The method for producing a decoloring stretchable fabric according to claim 1, wherein the dyed fabric is a sewn fabric product. The method for producing a decolorized stretchable fabric according to claim 1 or 2, wherein the retention rate of the elastic modulus of the decolorized stretchable fabric is 60% or more. The method for producing a decolorized stretchable fabric according to any one of claims 1 to 3, wherein a retention rate of tensile strength of the decolorized stretchable fabric is 60% or more. The method for producing a decolorized stretchable fabric according to any one of claims 1 to 4, wherein a color difference (ΔE * ab) between the stretchable fabric before decolorization and the stretchable fabric after decolorization is 5 or more.

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