FUNCTIONAL CASHMERE FIBER AND FABRICATION METHOD THEREOF

Abstract

A functional cashmere fiber includes a cashmere fiber, a boron-doped TiO.sub.2 layer and a carboxymethyl cellulose (CMC) binder. The CMC binder binds the boron-doped TiO.sub.2 layer on the cashmere fiber such that the boron-doped TiO.sub.2 layer at least partially covers the cashmere fiber. The functional cashmere fiber provides self-cleaning function under visible light and high washing stability.

Claims

1. A functional cashmere fiber comprising: a cashmere fiber; a layer comprising boron-doped titanium dioxide (TiO.sub.2); and a binder comprising carboxymethyl cellulose (CMC) for binding the layer on the cashmere fiber such that the layer at least partially covers the cashmere fiber.

2. The functional cashmere fiber of claim 1, wherein the boron-doped TiO.sub.2 has a molar ratio of boron to titanium between 0.3:1 and 1.2:1.

3. The functional cashmere fiber of claim 1, wherein the layer has a thickness between 10 nm and 100 nm.

4. The functional cashmere fiber of claim 1, wherein the layer fully covers the cashmere fiber.

5. The functional cashmere fiber of claim 1, wherein the cashmere fiber has a diameter between 5 μm and 30 μM.

6. The functional cashmere fiber of claim 1, wherein the boron-doped TiO.sub.2 has a molar ratio of boron to titanium between 0.9:1 and 1.1:1, and the layer has a thickness between 10 nm and 50 nm.

7. A functional yarn comprising the functional cashmere fiber of claim 1.

8. A functional fabric comprising the functional cashmere fiber of claim 1.

9. A method for fabricating the functional cashmere fiber of claim 1 comprising: providing a CMC-coated fiber, wherein the CMC-coated fiber is a cashmere fiber coated with CMC; and contacting the CMC-coated fiber with boron-doped TiO.sub.2 thereby forming the functional cashmere fiber.

10. The method of claim 9, wherein the boron-doped TiO.sub.2 has a molar ratio of boron to titanium between 0.3:1 and 1.2:1.

11. The method of claim 9 further comprising: contacting the cashmere fiber with a first solution comprising CMC thereby forming the CMC-coated fiber.

12. The method of claim 11, wherein the first solution is a CMC sodium salt solution.

13. The method of claim 11, wherein the first solution has a CMC concentration between 0.1% (v/v) and 1% (v/v).

14. The method of claim 9, wherein the step of contacting the CMC-coated fiber with boron-doped TiO.sub.2 comprises: contacting the CMC-coated fiber with a second solution comprising boron-doped TiO.sub.2 or a boron-doped TiO.sub.2 precursor thereby forming a boron-doped TiO.sub.2-CMC-coated fiber; and curing the boron-doped TiO.sub.2-CMC-coated fiber thereby forming the functional cashmere fiber.

15. The method of claim 14, wherein the boron-doped TiO.sub.2 precursor comprises a TiO.sub.2 precursor, a boron precursor and an acidic aqueous solution.

16. The method of claim 15, wherein the TiO.sub.2 precursor is a titanium alkoxide or titanium tetrachloride, the boron precursor is a trialkyl borate or boric acid, the acidic aqueous solution is acetic acid, nitric acid or hydrochloric acid.

17. The method of claim 14, wherein the step of curing comprises curing the boron-doped TiO.sub.2-CMC-coated fiber at a temperature between 90° C. and 150° C.

18. The method of claim 9, wherein the method for fabricating the functional cashmere fiber comprises: contacting a cashmere fiber with a first solution comprising CMC thereby forming the CMC-coated fiber, wherein the first solution is a CMC sodium salt solution having a CMC concentration between 0.4% (v/v) and 0.6% (v/v); contacting the CMC-coated fiber with a second solution comprising the boron-doped TiO.sub.2 or a boron-doped TiO.sub.2 precursor thereby forming a boron-doped TiO.sub.2-CMC-coated fiber, wherein the boron-doped TiO.sub.2 has a molar ratio of boron to titanium between 0.9:1 and 1.1:1; and curing the boron-doped TiO.sub.2-CMC-coated fiber at a temperature between 110° C. and 130° C. thereby forming the functional cashmere fiber.

19. A method for fabricating a functional cashmere yarn comprising: providing a CMC-coated yarn, wherein the CMC-coated yarn is a cashmere yarn coated with CMC; contacting the CMC-coated yarn with a second solution comprising the boron-doped TiO.sub.2 or a boron-doped TiO.sub.2 precursor thereby forming a boron-doped TiO.sub.2-CMC-coated yarn; and curing the boron-doped TiO.sub.2-CMC-coated yarn thereby forming the functional cashmere yarn.

20. A method for fabricating a functional cashmere fabric comprising: providing a CMC-coated fabric, wherein the CMC-coated fabric is a cashmere fabric coated with CMC; contacting the CMC-coated fabric with a second solution comprising the boron-doped TiO.sub.2 or a boron-doped TiO.sub.2 precursor thereby forming a boron-doped TiO.sub.2-CMC-coated fabric; and curing the boron-doped TiO.sub.2-CMC-coated fabric thereby forming the functional cashmere fabric.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0027] The appended drawings contain figures of certain embodiments to further illustrate and clarify the above and other aspects, advantages and features of the present invention. It will be appreciated that these drawings depict embodiments of the invention and are not intended to limit its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0028] FIG. 1 shows a schematic diagram depicting a cross-section of a functional cashmere fiber according to certain embodiments;

[0029] FIG. 2 shows a flow chart depicting a method for fabricating a functional cashmere fiber according certain embodiments;

[0030] FIG. 3 shows a flow chart depicting a method for fabricating a functional cashmere fiber according certain embodiments;

[0031] FIG. 4 shows methyl orange (MO) degradation test results for functional cashmere sweaters prepared with formulations of TO, BO, TB1 and TB2;

[0032] FIG. 5 shows MO degradation test results for a functional cashmere sweater prepared with TB2;

[0033] FIG. 6 shows washing stability test results for functional cashmere sweaters prepared with TB2 having different concentrations;

[0034] FIG. 7 shows MO degradation test results for functional white cashmere yarns prepared with TB2 with different immersion time before washing;

[0035] FIG. 8 shows MO degradation test results for functional white cashmere yarns prepared with TB2 under different immersion time after washing;

[0036] FIG. 9 shows red wine removal test results for a pristine cashmere fabric and a functional cashmere fabric prepared with TB2;

[0037] FIG. 10 shows coffee removal test results for a pristine cashmere fabric and a functional cashmere fabric prepared with TB2;

[0038] FIG. 11A shows a scanning electronic microscope (SEM) image of a pristine cashmere fabric;

[0039] FIG. 11B shows a SEM image of a functional cashmere fabric prepared with TB2; and

[0040] FIG. 12 shows X-ray diffraction (XRD) spectra of a pristine cashmere fiber and a functional cashmere fiber prepared with TO.

DETAILED DESCRIPTION OF THE INVENTION

[0041] The present disclosure provides a functional cashmere fiber comprising a cashmere fiber, a layer comprising boron-doped TiO.sub.2 and a binder comprising CMC. The binder binds the layer on the cashmere fiber such that the layer at least partially covers the cashmere fiber. The functional cashmere fiber provides a self-cleaning function under visible light and high washing stability.

[0042] FIG. 1 shows a schematic diagram depicting a cross-section of a functional cashmere fiber according to certain embodiments. The functional cashmere fiber 10 comprises a cashmere fiber 11, a boron-doped TiO.sub.2 layer 12 and a CMC binder 13. The CMC binder 13 binds the boron-doped TiO.sub.2 layer 12 on the cashmere fiber 11 such that the boron-doped TiO.sub.2 layer 12 covers the cashmere fiber 11 and the CMC binder 13 is at least partially located between the cashmere fiber 11 and the boron-doped TiO.sub.2 layer 12. The boron-doped TiO.sub.2 layer 12 is photocatalytic and provides a self-cleaning function under visible light through removal of contaminants attached thereon under photocatalytic reaction. The CMC binder 13 enables the boron-doped TiO.sub.2 layer 14 to be tightly bound on the cashmere fiber 11 for improving washing stability of the functional cashmere fiber 10.

[0043] In certain embodiments, the cashmere fiber is a fiber obtained from cashmere goats or similar thereto.

[0044] In certain embodiments, the cashmere fiber has a diameter between 5 μm and 30 μm, between 10 μm and 25 μm, or between 10 μm and 20 μm.

[0045] In certain embodiments, the boron-doped TiO.sub.2 layer partially covers the cashmere fiber.

[0046] In certain embodiments, the boron-doped TiO.sub.2 layer fully covers the cashmere fiber.

[0047] In certain embodiments, the boron-doped TiO.sub.2 layer comprises boron-doped TiO.sub.2 particles. The boron-doped TiO.sub.2 particles have a particle size between 10 nm and 50 nm, between 20 nm and 40 nm, or between 25 nm and 35 nm.

[0048] In certain embodiments, the boron-doped TiO.sub.2 layer has a thickness between 10 nm and 100 nm, between 30 nm to 80 nm, or between 50 nm to 60 nm.

[0049] In certain embodiments, the boron-doped TiO.sub.2 layer has a molar ratio of boron to titanium between 0.3:1 and 1.2:1, between 0.5:1 and 1:1, or between 0.9:1 and 1.1:1.

[0050] The functional cashmere fiber described herein can be used for making different functional textile products, e.g., yarns, fabrics, or clothes. The functional textile products comprising the functional cashmere fibers described herein can provides a self-cleaning function and high washing stability. In certain embodiments, a functional cashmere yarn comprises interlocked functional cashmere fiber described herein.

[0051] FIG. 2 shows a flow chart depicting a method for fabricating a functional cashmere fiber according certain embodiments. In step S21, a CMC-coated fiber is provided. The CMC-coated fiber is a cashmere fiber coated with CMC. In step S22, the CMC-coated fiber is contacted with boron-doped TiO.sub.2 thereby forming the functional cashmere fiber.

[0052] FIG. 3 shows a flow chart depicting a method for fabricating a functional cashmere fiber according certain embodiments. In step S31, a cashmere fiber is contacted with a CMC solution thereby forming a CMC-coated fiber. In step S32, the CMC-coated fiber is contacted with a boron-doped TiO.sub.2 solution thereby forming a boron-doped TiO.sub.2-CMC-coated fiber, which is coated with boron-doped TiO.sub.2 and CMC. In step S33, the boron-doped TiO.sub.2-CMC-coated fiber is cured thereby forming the functional cashmere fiber.

[0053] In certain embodiments, the boron-doped TiO.sub.2 has a molar ratio of boron to titanium between 0.3:1 and 1.2:1, between 0.5:1 and 1.2:1, or between 0.9:1 and 1.1:1.

[0054] In certain embodiments, the CMC solution is a CMC sodium salt solution.

[0055] In certain embodiments, the CMC solution has a CMC concentration between 0.1% and 1.0% (v/v), between 0.3% and 0.8% (v/v), or between 0.4% and 0.6% (v/v).

[0056] In certain embodiments, the boron-doped TiO.sub.2 solution comprises boron-doped TiO.sub.2 or a boron-doped TiO.sub.2 precursor.

[0057] In certain embodiments, the boron-doped TiO.sub.2 precursor comprises a TiO.sub.2 precursor, a boron precursor and an acidic aqueous solution. The TiO.sub.2 precursor can be titanium tetraisopropoxide or titanium tetrachloride. The boron precursor can be a trialkyl borate or boric acid. The acidic aqueous solution can be acetic acid, nitric acid, or hydrochloric acid. The boron-doped TiO.sub.2 solution can comprise titanium tetraisopropoxide having a concentration between 2% and 30% (v/v), between 2% and 10% (v/v), or between 2% and 5% (v/v).

[0058] In certain embodiments, the boron-doped TiO.sub.2-CMC-coated fiber is cured at a temperature between 90° C. and 150° C., between 100° C. and 140° C., or between 110° C. and 130° C. to stabilize the boron-doped TiO.sub.2 on the cashmere fiber.

Example 1: Preparation of Boron-Doped TiO.SUB.2 .Solution

[0059] A boron-doped TiO.sub.2 solution was prepared as follows: a first mixture of acetic acid and titanium tetraisopropoxide was added to tributyl borate to form a second mixture, water was added to the second mixture to form a third mixture, and the third mixture was heated at 60° C. under stiffing for 2 hr to form the boron-doped TiO.sub.2 solution comprising boron-doped TiO.sub.2 particles. Three solution formulations including TO, TB1 and TB2 were prepared and shown in Table 1. TO (control sample) contains TiO.sub.2 only, TB1 contains boron-doped TiO.sub.2 having a molar ratio of B:Ti being 0.5:1 and TB2 contains boron-doped TiO.sub.2 having a molar ratio of B:Ti being 1:1. TO is used to form a TiO.sub.2 layer, and TB1 and TB2 are used to form boron-doped TiO.sub.2 layers having different molar ratios.

TABLE-US-00001 TABLE 1 Molar ratio of Molar ratio of Concentration Formulation B:Ti B: CH.sub.3COOH of B (mol/L) TO — 1:5 0 TB1 0.5:1 1:5 0.08 TB2   1:1 1:5 0.16

Example 2: Preparation of Functional Cashmere Sweaters

[0060] Step 1: A white cashmere sweater was washed by a non-ionic detergent at 40° C. for 6 min using a tumble dryer. After being dried, the cashmere sweater was dipped into the 0.5% (v/v) of CMC sodium salt solution in a washing machine for 5 min to form a CMC-coated sweater. Then, the CMC-coated sweater was washed with water.

[0061] Step 2: The CMC-coated sweater was dipped into the boron-doped TiO.sub.2 solution in a washing machine for 5 min to form a boron-doped TiO.sub.2-CMC-coated sweater. Then, the boron-doped TiO.sub.2-CMC-coated sweater was dried at 60° C. and cured at 120° C. for 3 min for coating the sweater with the boron-doped TiO.sub.2 layer to form a functional sweater. The functional sweater was washed with water and then dried.

Example 3: Preparation of Functional Cashmere Yarns

[0062] Step 1: A white cashmere yarn was washed by a non-ionic detergent at 40° C. for 30 min. After being dried, the cashmere yarn was placed in a proofer machine containing 0.5% (v/v) CMC sodium salt solution at 25° C. for 3 min to form a CMC-coated yarn. Then, the CMC-coated yarn was washed with water.

[0063] Step 2: The CMC-coated yarn was placed in a proofer machine containing the boron-doped TiO.sub.2 solution at 25° C. to form a boron-doped TiO.sub.2-CMC-coated yarn. Then, a centrifuge machine was used to remove the excess solution on the boron-doped TiO.sub.2-CMC-coated yarn. Afterwards, the boron-doped TiO.sub.2-CMC-coated yarn was dried at 60° C. and cured at 120° C. for 3 min for coating the yarn with the boron-doped TiO.sub.2 layer to form the functional cashmere yarn. The functional cashmere yarn was washed with water and then dried.

[0064] Step 3: The functional cashmere yarn was further treated by spraying with water and waxing. Then, the treated yarn was knitted to a swatch.

Example 4: Methyl Orange (MO) Degradation Test

[0065] MO degradation tests were conducted in a box equipped with fluorescent lamps and a shaker under the following conditions: [0066] Fabric size: 2*2 cm.sup.2 [0067] MO solution: 15.3 μM [0068] Visible light intensity: ˜8 mW/cm.sup.2 [0069] UV light intensity: ˜84.9 μW/cm.sup.2

[0070] The functional cashmere fabrics described herein and control samples were immersed in dishes containing 25 mL MO (15.3 μM) solution. The dishes were placed on the shaker and exposed to the light source. The original MO solution was also exposed to irradiation under the same condition. At a given time interval, 2 ml of the MO solution was collected. The change in concentration of MO was measured by an UV-vis spectrophotometer at a wavelength of 464 nm.

Example 5: Washing Stability Test

[0071] Samples were washed with 5 times to test their washing stability. The tests were conducted according to AATCC-143 test method.

[0072] The experiment conditions are shown as follows: [0073] Nonionic detergent (2 g/L) [0074] 400 rpm, 30 min, at room temperature

[0075] FIG. 4 shows MO degradation test results for functional cashmere sweaters prepared with TO, BO (containing boron oxide only), TB1 and TB2. The MO concentrations for the functional cashmere sweaters prepared with TB1 and TB2 are reduced by 50% and 57% under UV light after 210 min, while the MO concentrations for the cashmere sweaters prepared with TO and BO are merely reduced by 20% under UV-light after 210 min. The test results show that boron-doped TiO.sub.2 provide better self-cleaning performance than TiO.sub.2 or boron oxide. TB2 provides better self-cleaning performance than TB1, showing that the self-cleaning performance is improved when more boron is doped into TiO.sub.2.

[0076] FIG. 5 shows MO degradation test results for a functional cashmere sweater prepared with TB2. Three sections of the functional cashmere sweater were cut out for testing. The MO concentrations of the three sections are reduced by 94% under visible light after 7.5 hr.

[0077] FIG. 6 shows washing stability test results for functional cashmere sweaters prepared with TB2 having different boron-doped TiO.sub.2 concentrations. Before washing, the MO concentrations for the functional cashmere sweaters prepared with 2.5% and 5% (v/v) TB2 concentrations are similarly reduced by 97% under visible light after 8.5 hr. After washing with 5 times, the MO concentrations for the functional cashmere sweaters prepared with 2.5% and 5% (v/v) TB2 concentrations are reduced by 85% and 91% respectively under visible light after 8.5 hr. The results show that the functional cashmere sweaters still provide good self-cleaning performance after washing due to the presence of CMC layer. In addition, the functional cashmere sweater prepared with higher boron-doped TiO.sub.2 concentrations provides better self-cleaning performance after washing.

[0078] FIG. 7 shows MO degradation test results for functional white cashmere yarns prepared with TB2 with different immersion time before washing. The MO concentrations for the functional yarns prepared with immersion time of 5, 10 and 15 min (referring to the time for the yarn being immersed in the boron-doped TiO.sub.2 solution) are reduced by 99% under visible light after 90 min, while the MO concentration of a pristine white yarn (control sample) is merely reduced by 5%. The results show that the functional cashmere yarns provide self-cleaning function while the pristine yarn fails to provide the same function.

[0079] FIG. 8 shows MO degradation test results for functional white cashmere yarns prepared with TB2 under different immersion time after washing. After washing with five times, the MO concentrations of the functional cashmere yarns prepared with immersion time of 5, 10 and 15 min are reduced by 91% under visible light after 5.5 hr. The functional cashmere yarn prepared with shorter immersion time (e.g., 5 min) has faster decay in MO concentration comparing with those prepared with longer immersion time (e.g., 10 and 15 min).

Example 6: Red Wine Removal Test

[0080] A red wine removal test was conducted as follows: dropping 100 μL red wine on a fabric, leaving the red wine on the fabric for 30 min, rinsing the fabric with water, irradiating the fabric with stain for 20 hr under visible light, observing the residual color on the fabric and recording color change on the fabric by taking photos.

[0081] FIG. 9 shows results of red wine removal tests for a functional cashmere fabric 91 prepared with TB2 and a pristine cashmere fabric 92. As shown in the photo of FIG. 9, no stain (bottom left of the photo) is found on the surface of a functional cashmere fabric 91 under visible light for 20 hr while an obvious stain 93 (bottom right of the photo) is still found on the surface of the pristine cashmere fabric 92 under visible light for 20 hr.

Example 7: Coffee Removal Test

[0082] A coffee removal test was conducted as follows: dropping 100 μL coffee on a fabric, leaving the coffee on the fabric for 30 min, rinsing the fabric with water, irradiating the fabric with stain for 20 hr under visible light, observing the residual color on the fabric and recording color change on the fabric by taking photos.

[0083] FIG. 10 shows coffee removal test results for a functional cashmere fabric 101 prepared with TB2 and a pristine cashmere fabric 102. No stain (bottom left of the photo) is observed on the surface of the functional cashmere fabric 101 while an obvious stain 103 (bottom right of the photo) is observed on the surface of the pristine cashmere fabric 102.

[0084] FIG. 11A shows a SEM image of a pristine cashmere fabric. As shown in FIG. 11A, the pristine cashmere fabric includes pristine cashmere fibers 111. FIG. 11B shows a SEM image of a functional cashmere fabric prepared with TB2. As shown in FIG. 11B, the functional cashmere fabric includes functional cashmere fibers 112. The functional cashmere fibers 112 are covered by boron-doped TiO.sub.2 layers 113 comprising boron-doped TiO.sub.2 nano-particles.

[0085] FIG. 12 shows XRD spectra of a pristine cashmere fiber and a functional cashmere fiber prepared with TO. The results show that the TiO.sub.2 layer is coated on the cashmere fiber.

[0086] Thus, it can be seen that the present disclosure provides visible-light active self-cleaning formulations and methods for fabricating functional cashmere fibers, yarns, fabrics, or textile products. Functionalization of cashmere fibers, yarns, fabrics, or textile products with photocatalytic boron-doped TiO.sub.2 coating enables the removal of contaminates by a light-triggered oxidation mechanism. Adopting CMC as a binder improves the washing stability of the self-cleaning coating. Apart from stain resistance, the functional cashmere fibers, yarns, fabrics or textile products described herein provides little impact on hand feel (e.g., change with 5-10% based on a fabric touch testing) and color change (e.g., 1 scaling based on AATCC evaluation procedure for grey scale).

[0087] Although the invention has been described in terms of certain embodiments, other embodiments apparent to those of ordinary skill in the art are also within the scope of this invention. Accordingly, the scope of the invention is intended to be defined only by the claims which follow.