Ultrasonic wave and papain modified wool low-temperature dyeing method

Abstract

The invention discloses an ultrasonic wave and papain modified wool low-temperature dyeing method, which comprises: (1) placing a wool fabric in a pretreatment liquid, carrying out oscillation treatment, washing with water, and drying to prepare a pretreated wool fabric; (2) putting the pretreated wool fabric into a modification solution, then carrying out ultrasonic treatment, and after the treatment is completed, washing and drying to obtain a modified wool fabric; and (3) putting the modified wool fabric into the dye liquor, dyeing, taking out after dyeing, washing with tap water, washing with deionized water, and drying to obtain a finished product. Through the synergistic effect of the ultrasonic cavitation effect and the papain, the hydrolysis effect of the enzyme on the scale layer of the wool is enhanced, the problems that the single enzyme treatment reaction is uneven and the efficiency is low are solved, and the dye uptake of the modified wool at the low temperature of 70 DEG C reaches 98.7% or above.

Description

Technical Field

[0001] This invention relates to the field of textile printing and dyeing technology, and in particular to a low-temperature dyeing method for wool modified with ultrasound-assisted papain. Background Technology

[0002] Wool fabrics are widely loved by consumers for their excellent warmth, soft feel, and breathability. However, the unique scaly structure of wool fibers means that dyeing requires a high temperature of 95-98℃. Prolonged high-temperature treatment not only consumes a great deal of energy but also causes problems such as reduced wool fiber strength, yellowing of the fabric, and a rough feel, seriously affecting the product's performance.

[0003] To achieve low-temperature dyeing of wool, researchers have developed various technical solutions. Among them, enzyme modification technology uses proteases to hydrolyze the wool scale layer, reducing dye diffusion resistance and effectively lowering the dyeing temperature. However, single enzyme treatment has drawbacks such as low reaction efficiency, uneven scale layer hydrolysis, and enzyme activity being easily affected by the environment. Furthermore, the high cost of enzyme preparations limits industrial application. Ultrasonic technology in the dyeing and finishing field mainly utilizes the cavitation effect to improve dye liquor permeability, but its effect on modifying the wool scale layer is limited when used alone, making it difficult to achieve the ideal low-temperature dyeing effect.

[0004] Modification with papain alone relies on the natural diffusion of enzyme molecules to the surface of the wool cuticle layer and the catalytic reaction. However, due to the hydrophobic barrier and steric hindrance of the cuticle layer, enzyme molecules struggle to penetrate deep into the cuticle, causing the hydrolysis reaction to concentrate on the fiber surface. Furthermore, enzyme activity is easily affected by substrate concentration and pH fluctuations in the reaction system, requiring large amounts of enzyme preparation to achieve the desired effect. In contrast, ultrasonic treatment alone only improves the flowability and permeability of the dye liquor, failing to fundamentally destroy the protein structure of the cuticle layer. Its effect on reducing dye diffusion resistance is limited, and high dyeing rates are still difficult to achieve at low temperatures. More importantly, unsuitable ultrasonic conditions can inhibit the catalytic activity of papain: the cavitation effect of ultrasound creates localized high-temperature and high-pressure environments. If parameters are not properly controlled, the spatial conformation of papain can be easily disrupted, leading to enzyme inactivation. Conversely, reducing the ultrasonic intensity to protect enzyme activity prevents it from enhancing mass transfer and breaking down the cuticle layer. In addition, the scale layer structure of wool fibers is heterogeneous, and the degree of protein cross-linking and hydrophobic properties vary in different regions. Simply combining the two technologies cannot achieve uniform modification, and may even lead to an aggravated loss of fabric strength due to excessive local reaction. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a low-temperature dyeing method for wool modified with ultrasound and papain. This invention utilizes the synergistic effect of ultrasonic cavitation and papain to not only enhance the hydrolytic effect of the enzyme on the wool cuticle layer but also solves the problems of uneven reaction and low efficiency associated with single enzyme treatment. The modified wool achieves a dye uptake rate of over 98.7% at 70℃. This low-temperature wool dyeing method, which balances dyeing effect, fabric performance, and production cost, has significant practical application value.

[0006] The technical solution of the present invention is as follows: The purpose of this invention is to provide a low-temperature dyeing method for wool modified with papain using ultrasound synergistic effect, comprising the following steps: (1) Pretreatment: Place the wool fabric in the pretreatment solution and treat it in a water bath constant temperature shaker. After treatment, wash it with water and dry it to obtain the pretreated wool fabric. (2) Synergistic modification: The pretreated wool fabric obtained in step (1) is placed in the modification liquid and placed in an ultrasonic device. The ultrasonic treatment is carried out in an intermittent working mode of working for 30 seconds and pausing for 10 seconds. After the treatment is completed, the wool fabric is washed and dried to obtain the modified wool fabric. (3) Low temperature dyeing: The modified wool fabric obtained in step (2) is placed in the dyeing solution and dyed in the HSCW-38 ambient temperature and pressure dyeing machine. After dyeing, it is taken out and rinsed with tap water until there is no floating color. Then it is washed with deionized water and dried to obtain the finished product.

[0007] Before pretreatment, wool fabrics are cut into 8×8cm sizes (each piece weighs about 2.5g), rinsed twice with tap water, then washed with deionized water, and dried in a 60℃ electric hot air drying oven for 30 minutes for later use.

[0008] In one embodiment of the present invention, in step (1), the pretreatment solution consists of: 30% hydrogen peroxide 30mL / L, anhydrous sodium carbonate 0.4% owf, sodium silicate nonahydrate 4g / L, and the remainder is water.

[0009] In one embodiment of the present invention, in step (1), the ratio of wool fabric to pretreatment liquid is 1:25; the conditions set for the water bath constant temperature shaker are: temperature 50°C, time 60 min, oscillation frequency 150 r / min; and drying temperature 60°C.

[0010] In one embodiment of the present invention, the treatment step (1) can effectively destroy the hydrophobic lipid layer on the surface of the wool scale layer, and break the disulfide bonds of the peptide chain crosslinking in the scale layer, creating conditions for subsequent enzyme treatment and dye penetration, and can improve the whiteness of wool fabric.

[0011] In one embodiment of the present invention, in step (2), the modified solution consists of: 3% papain owf (enzyme activity ≥200000U / 3g), 0.2g / L anhydrous calcium chloride, pH adjusted to 6-8 by the buffer solution, and the remainder is water.

[0012] In one embodiment of the present invention, in step (2), the bath ratio of the pretreated wool fabric to the modified liquid is 1:50.

[0013] In one embodiment of the present invention, in step (2), the conditions for ultrasonic treatment are: ultrasonic power of 300~500W, frequency of 20~40kHz, and treatment at 55±1℃ for 2h; the temperature is controlled by a water bath during ultrasonic treatment.

[0014] The optimal frequency range for synergistic effect is 20~40kHz. This frequency range is the optimal range for the synergistic effect of ultrasound and papain. Within this range, the ultrasonic cavitation effect can promote enzyme penetration without destroying enzyme activity. Beyond this range, the ultrasonic cavitation effect and enzyme activity become unbalanced, resulting in a decrease in modification effect. High-frequency ultrasound can easily cause damage to the enzyme spatial conformation and reduce catalytic efficiency.

[0015] In one embodiment of the present invention, in step (2), the cavitation effect of ultrasound can promote the penetration of papain molecules into the wool scale layer, while enhancing the interaction between the enzyme and the scale layer protein and accelerating the hydrolysis of the scale layer; while anhydrous calcium chloride, as an enzyme activator, can further enhance the catalytic activity of papain. The two work together to achieve uniform and efficient modification of the wool scale layer, and can reduce the amount of enzyme used and shorten the reaction time.

[0016] In one embodiment of the present invention, in step (3), the dyeing procedure is as follows: start dyeing at 30°C, raise the temperature to 70°C at a rate of 2°C / min, and keep warm for 1 hour; during the dyeing process, maintain the dye solution circulation rate at 5~8L / min.

[0017] In one embodiment of the present invention, in step (3), the dye solution consists of: Acid Blue R 2% owf, potassium sulfate 3g / L, pH adjusted to 2.0 with 10% dilute sulfuric acid, and the remainder is water.

[0018] In one embodiment of the present invention, in step (3), the ratio of the modified wool fabric to the dye liquor is 1:30.

[0019] A second objective of this invention is to provide a low-temperature dyed wool fabric obtained by the above method.

[0020] Beneficial effects: The method of this invention has significant synergistic effects. The synergistic effect of ultrasonic cavitation and papain not only enhances the hydrolysis effect of the enzyme on the wool scale layer, but also solves the problems of uneven reaction and low efficiency of single enzyme treatment. The dyeing rate of modified wool at a low temperature of 70℃ is more than 98.7%, while the dyeing rate of single papain modification is only 92.35% (Comparative Example 1), and the dyeing rate of single ultrasonic treatment is only 85.72% (Comparative Example 2).

[0021] The method of this invention causes minimal damage to the fabric. By employing low-temperature dyeing combined with synergistic modification, it effectively reduces the strength loss of wool fibers, resulting in a fabric strength reduction rate of less than 5.21%.

[0022] The dyeing performance of the method of the present invention is excellent. The fastness to soaping, fastness to brushing, and fastness to rubbing of the finished fabric are comparable to those of conventional boiling dyeing products. The dry rubbing fastness reaches grade 5, the wet rubbing fastness reaches grade 3-4, and the levelness is excellent (standard deviation of K / S value ≤ 0.5). Attached Figure Description

[0023] Figure 1 These are scanning electron microscope images of the wool fabrics before and after modification in Example 1; Figure 2 The image shows the Alvarden reaction of the wool fabrics before and after modification in Example 1 under a microscope. Detailed Implementation

[0024] Test methods 1. Determination of dyeing rate The effect of enzyme modification on wool fabrics treated with papain can be characterized by measuring the dye uptake rate. A standard solution was prepared according to the dyeing process formula, diluted 10 times, and labeled for testing. After dyeing, the residual dye solution in the dyeing cylinder was taken, diluted 3 times, and labeled for testing. The solution was then spectrally scanned using a UV-2600 ultraviolet spectrophotometer to determine the maximum absorption wavelength of the dye, and the absorbance of the solution at that wavelength was measured. The dye uptake rate was calculated using the following formula.

[0025]

[0026] Where n represents the dilution factor of the residual solution after staining, and A i A0 represents the absorbance of the staining residue diluted n times, where m represents the dilution factor of the staining solution before staining, and A0 represents the absorbance of the staining standard solution diluted m times.

[0027] 2. Determination of K / S value The K / S value (Kubelka-Munk function value) was determined according to GB / T 6688. The K / S value of the dyed wool fabric was measured using a CI7800 computer colorimeter from X-Rite Ltd. The instrument was calibrated first, and then five points at different locations on the fabric were randomly selected to measure the K / S value at the maximum absorption wavelength. The average value and standard deviation were used to characterize the levelness of the fabric dyeing.

[0028]

[0029] In the formula, R represents the reflectance of the dyed fabric, K represents its absorption coefficient, and S represents the scattering coefficient. The K / S value of each sample was tested three times and averaged.

[0030] 3. Levelness test The K / S data were analyzed, and the standard deviation was used to characterize the evenness of the fabric.

[0031] 4. Scanning electron microscope After pretreatment and papain-based ultrasonic treatment, the scale layer of wool fabric was hydrolyzed and destroyed. The changes in the wool scale layer were characterized using a Hitachi SU1510 scanning electron microscope (Japan). Twenty-four hours before testing, untreated, pretreated, and enzyme-ultrasonic treated wool fabrics were cut to appropriate sizes and mounted for gold sputtering. The test voltage was adjusted to 10 kV, magnification to 2000, and clear images of the scale layer were captured and analyzed.

[0032] 5. Fourier transform infrared spectroscopy Infrared spectroscopy was used to scan wool fabric samples that had not undergone treatment and those treated with papain and ultrasound, with a scanning wavelength range of 400–4000 cm⁻¹. -1 After scanning, the data were organized and plotted in Origin. The changes in functional groups in wool fabrics before and after enzyme treatment were analyzed and discussed.

[0033] 6. Alvarden reaction Whether wool can undergo the Alvarden reaction is an effective indicator of the integrity of its scale layer. When wool is oxidized by saturated bromine water, the keratin in the wool cortex transforms into brominated keratin. The increased hydrophilic groups cause it to swell strongly in water. Due to the internal pressure caused by this swelling, the undamaged scale layer begins to swell into convex bubbles at the weakest points where the scales are joined together, neatly arranged around the fiber. This is the Alvarden reaction phenomenon. Place the wool fabric on a glass slide, add a few drops of saturated bromine water, react for 5 minutes, and then cover with a coverslip as a sample. Adjust the microscope magnification to 400x and observe the wool scale layer structure. If bubbles appear on the untreated fiber surface, it indicates that the wool fabric's scale layer is intact and undamaged; otherwise, it indicates that the wool scale layer structure has been damaged and is no longer intact.

[0034] 7. Colorfastness test The main tests cover various properties of dyed wool fabrics, including fastness to soaping, fastness to rubbing, and fastness to brushing. Test samples include untreated dyed wool fabrics, wool fabrics dyed with papain using ultrasonic treatment, and wool fabrics dyed using conventional boiling.

[0035] a. Test method for fastness to washing with soap: According to GB / T3921-2008 "Textiles - Tests for color fastness - Fastness to washing with soap", cut untreated dyed wool fabrics, wool fabrics dyed with conventional high-temperature boiling, and wool fabrics dyed after papain ultrasonic treatment into 50mm×50mm pieces, and remove excess fringes for later use. Prepare the washing solution according to Table 1 below.

[0036] Table 1

[0037] The prepared soaping solution was preheated to 60°C in a water bath constant temperature shaker. Samples were sewn together with standard wool, cotton, and acrylic interlinings using thread free of fluorescent whitening agents, and clearly marked to prevent errors. Once the soaping solution reached 60°C, the samples were added and placed in an SW-24E type wash fastness tester. The holding temperature was set to 60°C for 45 minutes. After the test, the samples were removed, rinsed with deionized water for 5 minutes, and dried in a 60°C electric heating drying oven. The color fastness of the samples was rated according to GB / T250-2008 = ISO105 / A02-1993 "Textiles—Tests for color fastness—Assessment of color change using a grey scale," and the staining fastness was rated according to GB / T 251-2008 = ISO105 / A03-2019 "Textiles—Tests for color fastness—Assessment of staining using a grey scale."

[0038] b. Test method for rubbing fastness: According to GB / T 3920-2008 "Textiles - Tests for color fastness - Color fastness to rubbing", cut untreated dyed wool fabric, wool fabric dyed with conventional high-temperature boiling, and wool fabric dyed after papain ultrasonic treatment into 50mm × 140mm pieces, removing excess raw edges for later use. Cut a 50mm × 50mm piece of 100% cotton standard cotton lining fabric with 70% whiteness, attach it to the wool fabric with thread free of fluorescent whitening agents, and mark it. Rubbing fastness is further divided into dry rubbing fastness and wet rubbing fastness.

[0039] (1) Dry rubbing fastness test method: Fix both ends of the sample to the rubbing fastness tester, fix a standard dry rubbing cloth to the rubbing head of the instrument, adjust the running direction of the rubbing cloth so that its radial direction is consistent with the running direction, set the rubbing speed to 1 time / second, the time to 10s, the vertical pressure of the rubbing head to 9N, and the rubbing stroke to 100mm. After the test, use the "Grey Sample Card for Staining Assessment" to rate the staining fastness of the rubbing cloth.

[0040] (2) Wet rubbing fastness test method: The wet rubbing fastness test method is basically the same as that for dry rubbing. The only difference is that the moisture content of the rubbing cloth used for wet rubbing fastness is 95%-100%. Therefore, the rubbing cloth needs to be fully wetted in advance, and then squeezed by a small rubbing roller to make its moisture content reach the standard. After the test, the wet rubbing cloth needs to be dried at room temperature, and the staining fastness of the rubbing cloth is rated using the "Grey Chart for Staining Assessment".

[0041] c. Wash fastness test: According to GB / T 420-2009 "Textiles - Tests for color fastness - Pigment-dyed textiles - Wash fastness", untreated dyed wool fabrics, wool fabrics dyed with conventional high-temperature boiling, and wool fabrics dyed after papain ultrasonic treatment were cut into 250mm × 80mm pieces, with the longitudinal direction as the radial direction. 250ml of soaping solution was prepared according to Table 1, and the temperature was raised to 60℃. The samples were then immersed to ensure thorough wetting. After immersion for 1 minute, the samples were removed, excess solution was squeezed out, and the samples were laid flat on the plate of the wash fastness tester, secured at both ends with clamps. A nylon brush was placed on the sample, the switch was turned on, and the brushing speed was set to 1 stroke / second for 50 seconds, the vertical pressure of the friction head to 9N, and the friction stroke to 100mm. After brushing for 25 seconds, 100ml of soaping solution was added to ensure thorough wetting. After the test, the samples were removed, washed with warm water, and dried at room temperature. The color fastness of the samples was rated using the "Grey Chart for Assessing Color Change".

[0042] 8. Strong drop rate test Untreated, pretreated, and enzyme-ultrasonic treated fabrics, as well as dyed fabrics and conventionally high-temperature boil-dyed wool fabrics, were cut into 250mm × 60mm pieces as samples. The tensile strength and elongation at break of the samples were measured using a YG(B)026H-250 electronic fabric tensile strength tester, and the average values ​​were calculated. During testing, the air pump was turned on, one end of the fabric was first fixed to the clamp above the instrument to allow it to hang naturally, then the lower end was fixed, and the instrument was started.

[0043] The rate of drop is calculated using the following formula:

[0044] The above formula illustrates the relationship between the strength reduction rate and the strength of the fabric before and after dyeing.

[0045] Example 1 (1) Pretreatment of wool fabrics: Take 1000g / m wool fabric produced by Wuxi Xiexin Wool Textile Co., Ltd. 2 Wool fabric, cut to 8×8cm dimensions (weight 2.5g), rinsed twice with tap water, washed with deionized water, and dried at 60℃ for 30min. Pretreatment solution was prepared: 30% hydrogen peroxide 30ml / L, anhydrous sodium carbonate 0.4% owf, sodium silicate nonahydrate 4g / L, bath ratio 1:25.

[0046] The wool fabric was placed in the pretreatment solution, immersed, and then placed in a 50℃ water bath constant temperature shaker (oscillation frequency of 150r / min) for 60 minutes. After treatment, it was rinsed twice with tap water, then washed with deionized water, and dried at 60℃ to obtain the pretreated wool fabric.

[0047] (2) Ultrasonic-papain synergistic modification: The modification solution was prepared with 3% owf papain (enzyme activity 200000U / 3g) produced by Nanning Pangbo Biotechnology Co., Ltd., and 0.2g / L anhydrous calcium chloride. The pH was adjusted to 7.0, and the bath ratio was 1:50. The pretreated wool fabric was placed in the modification solution and placed in an ultrasonic device (power 400W, frequency 30kHz). The device was operated intermittently (30s / 10s) and treated at 55℃ for 2h. After washing and drying, the modified wool fabric was obtained.

[0048] (3) Low-temperature dyeing: Prepare the dye bath: Acid Blue R2 %owf produced by Shanghai Annoqi Group Co., Ltd., potassium sulfate 3g / L, adjust the pH to 2.0 with 10% dilute sulfuric acid, and the bath ratio is 1:30. Put the modified wool fabric into the dye bath and dye it in an HSCW-38 ambient temperature and pressure dyeing machine. Start dyeing at 30℃, raise the temperature to 70℃ at 2℃ / min, keep it at 70℃ for 1h, and the dye bath circulation rate is 6L / min. After dyeing, rinse with tap water until there is no floating color, then wash with deionized water and dry to obtain the finished product.

[0049] Scanning electron microscope images of wool fabrics before and after modification are shown below. Figure 1 As shown, a is untreated wool fabric, b is pretreated wool fabric, and c is dyed finished wool fabric. Figure 1 It is evident that the scale layer structure of wool treated with papain and ultrasound is damaged, the dye diffusion barrier is reduced, and the wool fiber's ability to adsorb and diffuse dye is improved.

[0050] Whether the Alvarden reaction occurs is an important criterion for determining whether the scale layer of a wool fabric is intact. Figure 2 These are microscopic images of the Alvarden reaction of wool fabrics before and after modification in this embodiment. a represents the untreated wool fabric, and b represents the dyed finished wool fabric. Figure 2 It can be observed that after reacting wool fabric with saturated bromine water, a large number of bubbles are generated due to the integrity of its scale layer. However, no bubbles are observed in the fabric treated with papain and ultrasound, indicating that the Alvarden reaction cannot occur. This confirms that the scale layer of the wool fabric is indeed destroyed after enzyme treatment. Furthermore, the cavitation effect of ultrasound promotes enzyme molecule penetration, uniformly hydrolyzes the scale layer, reduces fiber damage caused by excessive local hydrolysis, and results in a lower strength reduction rate than single enzyme treatment. Uniform hydrolysis of the scale layer makes the dye binding stronger and improves the staining fastness. The dyeing rate in Example 1 is close to that of high-temperature boiling dyeing (Comparative Example 3), and the strength reduction rate is even lower.

[0051] Example 2 Same as Example 1, except that in step (2), the pH of the modified liquid is 6.5; ultrasonic equipment parameters: power 300W, frequency 20kHz, intermittent operation (30s / 10s), 55℃ treatment for 2h.

[0052] Example 3 Same as Example 1, except that in step (2), the pH of the modified liquid is 8.0; the ultrasonic equipment parameters are: power 500W, frequency 40kHz, intermittent operation (30s / 10s), and treatment at 55℃ for 2h.

[0053] Comparative Example 1 Same as Example 1, except that in step (2), the ultrasonic treatment process is omitted, and the pretreated wool fabric is placed in the modified liquid, treated at 55°C for 2 hours, and then washed and dried.

[0054] Comparative Example 2 Same as Example 1, except that in step (2), the modified solution consists of 0.2 g / L of anhydrous calcium chloride, the pH of the buffer solution is adjusted to 6-8, and the remainder is water.

[0055] Comparative Example 3 Same as Example 1, except that in step (2), the pH of the modified liquid is 6.5; ultrasonic equipment parameters: power 300W, frequency 100kHz, intermittent operation (30s / 10s), 55℃ treatment for 2h.

[0056] Comparative Example 4 Same as Example 1, except that in step (2), the pH of the modified liquid is 6.5; ultrasonic equipment parameters: power 300W, frequency 160kHz, intermittent operation (30s / 10s), 55℃ treatment for 2h.

[0057] Comparative Example 5 Same as Example 1, except that in step (2), papain in the modified solution is replaced with trypsin, and the pH is 6.5.

[0058] The test results of the finished fabrics obtained in Examples 1-3 and Comparative Examples 1-5 are shown in Table 2 below.

[0059] Table 2

[0060] The comparison results show that the ultrasonic-papain synergistic modification scheme of the present invention has a significantly higher staining rate than single enzyme treatment or single ultrasonic treatment, and its comprehensive staining performance has obvious advantages.

[0061] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for low-temperature dyeing of wool using ultrasound-assisted papain modification, characterized in that, Includes the following steps: (1) Pretreatment: Place the wool fabric in the pretreatment solution and treat it in a water bath constant temperature shaker. After treatment, wash it with water and dry it to obtain the pretreated wool fabric. (2) Synergistic modification: The pretreated wool fabric obtained in step (1) is placed in the modification liquid and placed in an ultrasonic device. The ultrasonic treatment is carried out in an intermittent working mode of working for 30 seconds and pausing for 10 seconds. After the treatment is completed, the wool fabric is washed and dried to obtain the modified wool fabric. (3) Low temperature dyeing: The modified wool fabric obtained in step (2) is placed in the dyeing solution and dyed in the HSCW-38 ambient temperature and pressure dyeing machine. After dyeing, it is taken out and rinsed with tap water until there is no floating color. Then it is washed with deionized water and dried to obtain the finished product.

2. The method according to claim 1, characterized in that, In step (1), the pretreatment solution consists of: 30% hydrogen peroxide 30mL / L, anhydrous sodium carbonate 0.4% owf, sodium silicate nonahydrate 4g / L, and the remainder is water.

3. The method according to claim 1, characterized in that, In step (1), the ratio of wool fabric to pretreatment liquid is 1:25; the conditions set for the water bath constant temperature shaker are: temperature 50℃, time 60min, oscillation frequency 150 r / min; drying temperature 60℃.

4. The method according to claim 1, characterized in that, In step (2), the modified solution consists of: 3% papain owf (enzyme activity ≥200000U / 3g), 0.2g / L anhydrous calcium chloride, pH adjusted to 6~8 by the buffer solution, and the remainder is water.

5. The method according to claim 1, characterized in that, In step (2), the ratio of the pretreated wool fabric to the modified liquid is 1:

50.

6. The method according to claim 1, characterized in that, In step (2), the conditions for ultrasonic treatment are: ultrasonic power 300~500W, frequency 20~40kHz, and treatment at 55±1℃ for 2h; the temperature is controlled by a water bath during ultrasonic treatment.

7. The method according to claim 1, characterized in that, In step (3), the dyeing procedure is as follows: start dyeing at 30℃, raise the temperature to 70℃ at a rate of 2℃ / min, and keep warm for 1h; during the dyeing process, maintain the dye solution circulation rate at 5~8L / min.

8. The method according to claim 1, characterized in that, In step (3), the dye solution consists of: Acid Blue R 2% owf, potassium sulfate 3 g / L, pH adjusted to 2.0 with 10% dilute sulfuric acid, and the remainder is water.

9. The method according to claim 1, characterized in that, In step (3), the ratio of the modified wool fabric to the dye liquor is 1:

30.

10. A low-temperature dyed wool fabric prepared by the method according to any one of claims 1-9.

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