A dark dyeing process for water-saving cotton fabric

Abstract

The invention relates to the field of textile printing and dyeing, and discloses a water-saving cotton fabric dark dyeing process. The process comprises the following steps: taking cotton fabric for modification treatment to obtain modified cotton fabric; soaking the modified cotton fabric with deionized water, with a modified reactive dye dosage of 1-3% (owf), a bath ratio of 1:20-40, and an ethanol volume fraction of 80-90%; dyeing at room temperature, heating to 40-60°C at a heating rate of 2-5°C / min, dyeing for 1-2h, adding alkali, heating to 60-90°C, fixing for 20-50min, then cooling to 30-40°C at a cooling rate of 2-5°C / min, finishing dyeing, washing with water, soaping, and drying. The invention improves the dyeing performance of cotton fabric by modifying cotton fabric and reactive dye, and achieves uniform dyeing. At the same time, ethanol / water mixed solvent is used as a system for reactive dye dyeing cotton fabric, thereby reducing the amount of water, enabling reactive dye to dye cotton fabric under salt-free conditions, and reducing the discharge of dyeing wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of textile printing and dyeing, and particularly relates to a dark dyeing process for water-saving cotton fabric. Background Art

[0002] Cotton fabrics have attracted people's attention due to their good hydrophilicity, air permeability, softness and other characteristics. As the main dye for cotton fabric dyeing, the amount of reactive dyes has also increased significantly. Reactive dye dyeing usually uses water as the medium. Because reactive dyes generally have low directness and low dye uptake, a large amount of neutral electrolytes must be added during the dyeing process to promote dyeing, improve the dye uptake and reduce dye waste. However, a large amount of inorganic salts in the wastewater cannot be degraded autonomously and are difficult to recycle, which increases the difficulty of wastewater treatment and pollutes the environment. On the other hand, reactive dye water bath dyeing uses a large amount of water, which causes part of the dye to hydrolyze, resulting in a decrease in the fixation rate. At the same time, there are some hydrolyzed dyes in the dyeing wastewater, which seriously pollutes the water source. The discharge of dyeing wastewater has brought many ecological problems. With the increasing shortage of water resources and the enhancement of people's environmental awareness, reactive dye salt-free and water-free dyeing has gradually become an important direction for dyeing technology research. Summary of the invention

[0003] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a water-saving cotton fabric dark dyeing process, by modifying the cotton fabric and reactive dyes, the dyeing performance of the cotton fabric is improved, and the dyeing is uniform, and at the same time, ethanol / water mixed solvent is used as the reactive dye dyeing system for cotton fabric, which reduces the amount of water used, so that the reactive dye can dye the cotton fabric under salt-free conditions, thereby reducing the discharge of dyeing wastewater.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A dark dyeing process for water-saving cotton fabric comprises the following steps:

[0006] S1, taking cotton fabric and performing modification treatment to obtain modified cotton fabric;

[0007] S2, soaking the modified cotton fabric with deionized water, using 1-3% (owf) of the modified reactive dye, with a bath ratio of 1:20-40 and an ethanol volume fraction of 80-90%;

[0008] S3. Dye at room temperature, heat up to 40-60℃ at a heating rate of 2-5℃ / min, dye for 1-2h, add alkali, heat up to 60-90℃, fix for 20-50min, then cool down to 30-40℃ at a cooling rate of 2-5℃ / min, wash with water, soap and dry.

[0009] Preferably, the method for preparing the modified cotton fabric in step S1 comprises the following steps:

[0010] (1) placing cotton fabric in an alkaline solution with a bath ratio of 1:50, wherein the mass fraction of sodium hydroxide is 20% and the volume fraction of ethanol is 40%, stirring the solution at 50-70° C. for 1-2 hours, and then fully washing and drying the solution to obtain an alkaline-treated cotton fabric;

[0011] (2) The alkalized cotton fabric is immersed in a modifier solution with a bath ratio of 1:50, wherein the mass fraction of sodium chloroacetate is 20% and the volume fraction of ethanol is 40%, and the fabric is stirred at 50-70°C for 1-2 hours. After the reaction is completed, the fabric is washed and dried, and then the excess alkali on the fabric is neutralized with an acetic acid solution to obtain a modified cotton fabric.

[0012] Preferably, the preparation method of the modified reactive dye in step S2 comprises the following steps:

[0013] A. Add 2-hydroxymethylpyridine and 1-bromotetradecane to a reactor containing 1,4-dioxane solvent, place at 95-110° C. and stir for 36-48 hours. After the reaction is completed, rotary evaporate, wash, filter and dry to obtain a quaternary ammonium salt intermediate;

[0014] B. Place the quaternary ammonium salt intermediate, the catalyst dibutyltin dilaurate, the inhibitor hydroquinone and anhydrous dichloromethane in a reactor, stir and dissolve at 30-35° C., then heat to 40-55° C., add isocyanoethyl methacrylate, stir and react for 4-8 hours, and after the reaction is completed, rotary evaporate, wash and dry to obtain a quaternary ammonium salt cationic modifier;

[0015] C. Take a quaternary ammonium salt cationic modifier and add it to a reactor filled with deionized water, add methyl methacrylate and butyl acrylate in a nitrogen atmosphere, stir and react for 1 to 2 hours, heat to 75 to 90° C., keep warm for 5 to 10 minutes, then drop azobisisobutylamidine hydrochloride solution and react for 4 to 6 hours. After the reaction is completed, cool and filter to obtain a cationic microsphere dispersion;

[0016] D. Take the active dye in the reactor, place it in a water bath at 25-30℃ and slowly add the cationic microsphere dispersion dropwise for 1-1.5h. After the addition is completed, stir for 5-10min. Then adjust the pH value of the dye bath to 4-5 with hydrochloric acid, heat to 60-70℃ and dye for 2-3h. After the reaction is completed, cool to room temperature to obtain the modified active dye.

[0017] Preferably, in step A, the mass ratio of 2-hydroxymethylpyridine to 1-bromotetradecane is 1:5-5.5.

[0018] Preferably, in step B, the mass ratio of the quaternary ammonium salt intermediate to isocyanoethyl methacrylate is 2-3:1.

[0019] Preferably, in step C, the mass ratio of the quaternary ammonium salt cationic modifier, methyl methacrylate and butyl acrylate is 5 to 10:1 to 4:1.

[0020] Preferably, the concentration of the cationic microsphere dispersion in step D is 1-2 g / L, and the mass ratio of the reactive dye to the cationic microsphere dispersion is 0.08-1.2:1.

[0021] Preferably, the reactive dye is any one of CI Reactive Red 195, CI Reactive Yellow 95, and CI Reactive Blue 72.

[0022] Beneficial effects of the present invention:

[0023] The invention utilizes 2-hydroxymethyl pyridine to react with 1-bromotetradecane to synthesize a quaternary ammonium salt intermediate, and then reacts with isocyanoethyl methacrylate to synthesize a quaternary ammonium salt cationic modifier containing a double bond structure, and the quaternary ammonium salt cationic modifier, methyl methacrylate and butyl acrylate are mixed, and azobisisobutylamidine hydrochloride is used as an initiator to initiate copolymerization of methyl methacrylate, butyl acrylate and the quaternary ammonium salt cationic modifier in an aqueous phase to synthesize cationic polymer microspheres. Methyl methacrylate and butyl acrylate are nonionic monomers, butyl acrylate can increase the polymerization reaction rate to induce the formation of polymer microspheres, and at the same time, it plays a certain stabilizing role on the synthesized cationic polymer microspheres, and the quaternary ammonium salt cationic modifier is a cationic monomer, and the quaternary ammonium salt functional group in the structure makes the surface of the cationic polymer microsphere carry positive charge, and at the same time, the quaternary ammonium salt functional group has a broad-spectrum antibacterial effect, and can give cotton fabrics a good antibacterial effect. The invention utilizes active dyes to dye cationic polymer microspheres. The active dyes can be ionized in aqueous solution to generate sulfonic acid groups and carry negative charges. The surfaces of the cationic polymer microspheres carry positive charges due to the presence of quaternary ammonium salt groups. Due to the effects of electrostatic attraction, hydrogen bonds and van der Waals forces, the active dyes approach the cationic polymer microspheres and are adsorbed on the surfaces of the microspheres, thereby preparing modified active dyes.

[0024] The invention performs alkalization treatment on cotton fabric to remove impurities and make the surface of cotton fabric smoother. Then, the cotton fabric is treated with sodium chloroacetate to load carboxyl ions and anionize the cotton fabric, which can change the charging performance of the cotton fabric and improve the dyeing depth of the modified reactive dye on the cotton fabric. The modified reactive dye is used to dye the anionized cotton fabric, which makes up for the defect that the reactive dye can only be directly combined with the cotton fabric by hydrogen bond or van der Waals force. The cationic polymer microspheres are combined with the modified cotton fabric by covalent bond / ionic bond, which enhances the application effect of the cationic polymer microspheres on the cotton fabric. In addition, the cationic polymer microspheres have a large specific surface area and a uniform size, which reduces the reflectivity of the cotton fabric surface to light and increases the light absorption capacity of the fabric surface, resulting in a darker color of the dyed cotton fabric and effectively improves the utilization rate of the reactive dye. The present invention uses active dyes to dye cationic polymer microspheres, and then combines the cationic polymer microspheres with positive charges with cotton fabrics with negative charges. It does not need to add salt to promote dyeing like the traditional process, and adopts a salt-free and low-water dyeing process. The process flow is simple, energy-saving and consumption-reducing, and environmental pollution can be reduced. The present invention uses ethanol / water mixed solvent as a system for dyeing cotton fabrics with active dyes, reduces the amount of water, and allows the active dyes to dye cotton fabrics under salt-free conditions, thereby reducing the discharge of dyeing wastewater, and ethanol can be recycled and reused after dyeing, which is a green and environmentally friendly dyeing method. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The cotton fabric in the embodiment and the comparative example of the present invention is 100% pure cotton plain weave fabric, 133g / m 2 , produced by Changshu Yanhao Textile Co., Ltd.; CI Reactive Red 195 is produced by Shanghai Anochi Group Co., Ltd.

[0027] Embodiment 1 A method for preparing a modified cotton fabric comprises the following steps:

[0028] (1) Put the cotton fabric into an alkaline solution with a bath ratio of 1:50, wherein the mass fraction of sodium hydroxide is 20% and the volume fraction of ethanol is 40%, and stir the solution at 60°C for 1 hour, then wash and dry the solution to obtain an alkaline treated cotton fabric:

[0029] (2) The alkalized cotton fabric was immersed in a modifier solution with a bath ratio of 1:50, wherein the mass fraction of sodium chloroacetate was 20% and the volume fraction of ethanol was 40%, and the fabric was stirred at 60°C for 1 hour. After the reaction was completed, the fabric was washed and dried, and then the excess alkali on the fabric was neutralized with a 1% acetic acid solution to obtain a modified cotton fabric.

[0030] Embodiment 2 A method for preparing a modified reactive dye comprises the following steps:

[0031] A. Take 5g of 2-hydroxymethylpyridine and 25.7g of 1-bromotetradecane and add them to a reactor containing 200mL of 1,4-dioxane solvent, place it at 105°C and stir to react for 48h. After the reaction is completed, rotary evaporate, wash, filter and dry to obtain a quaternary ammonium salt intermediate;

[0032] B. Take 5g of quaternary ammonium salt intermediate, 0.002g of catalyst dibutyltin dilaurate, 0.03g of inhibitor hydroquinone and 100mL of anhydrous dichloromethane in a reactor, stir and dissolve at 30°C, then heat to 40°C, add 2g of isocyanoethyl methacrylate, stir and react for 6h, and after the reaction is completed, rotary evaporate, wash and dry to obtain a quaternary ammonium salt cationic modifier;

[0033] C. Take 5g of quaternary ammonium salt cationic modifier and add it to a reactor filled with 100mL of deionized water, add 4g of methyl methacrylate and 1g of butyl acrylate in a nitrogen atmosphere, stir and react for 2h, heat to 85°C, keep warm for 5min, then drop 10g / L of azobisisobutylamidine hydrochloride solution and react for 6h. After the reaction is completed, cool and filter to obtain a cationic microsphere dispersion;

[0034] D. Take 15mL of 0.2g / L Reactive Red 195 in a reactor, place it in a 25℃ water bath, and slowly drop 10mL of 1g / L cationic microsphere dispersion for 1h. After the addition is complete, stir for 5min, then adjust the pH value of the dye bath to 5 with hydrochloric acid, heat to 70℃ and dye for 2h. After the reaction is completed, cool to room temperature to obtain a modified reactive dye.

[0035] Embodiment 3 A water-saving cotton fabric dark dyeing process comprises the following steps:

[0036] S1. Take 3g of modified cotton fabric and soak it with deionized water, the amount of modified reactive dye is 1% (owf), the bath ratio is 1:20, and the volume fraction of ethanol is 80%;

[0037] S2. Dye at room temperature, heat up to 40℃ at a heating rate of 2℃ / min, dye for 2h, add 2g / L sodium hydroxide, heat to 60℃, fix for 30min, then cool to 30℃ at a cooling rate of 5℃ / min, finish dyeing, wash with water, soap and dry.

[0038] Embodiment 4 A water-saving cotton fabric dark dyeing process comprises the following steps:

[0039] S1. Take 3g of modified cotton fabric and soak it with deionized water, the amount of modified reactive dye is 2% (owf), the bath ratio is 1:30, and the volume fraction of ethanol is 90%;

[0040] S2. Dye at room temperature, heat up to 50℃ at a heating rate of 5℃ / min, dye for 1h, add 2g / L sodium hydroxide, heat to 70℃, fix for 50min, then cool to 30℃ at a cooling rate of 5℃ / min, finish dyeing, wash with water, soap and dry.

[0041] Embodiment 5 A dark dyeing process for water-saving cotton fabric comprises the following steps:

[0042] S1. Take 3g of modified cotton fabric and soak it with deionized water, the amount of modified reactive dye is 3% (owf), the bath ratio is 1:40, and the volume fraction of ethanol is 90%;

[0043] S2. Dye at room temperature, heat up to 60℃ at a heating rate of 2℃ / min, dye for 2h, add 2g / L sodium hydroxide, heat to 80℃, fix for 30min, then cool to 30℃ at a cooling rate of 5℃ / min, finish dyeing, wash with water, soap and dry.

[0044] Comparative Example 1 A dark dyeing process for water-saving cotton fabric comprises the following steps:

[0045] S1, take 3g cotton fabric and soak it with deionized water, the modified reactive dye dosage is 1% (owf), the bath ratio is 1:20, and the volume fraction of ethanol is 80%;

[0046] S2. Dye at room temperature, heat up to 40℃ at a heating rate of 2℃ / min, dye for 2h, add 2g / L sodium hydroxide, heat to 60℃, fix for 30min, then cool to 30℃ at a cooling rate of 5℃ / min, finish dyeing, wash with water, soap and dry.

[0047] Comparative Example 2 A dark dyeing process for water-saving cotton fabric comprises the following steps:

[0048] S1. Take 3g of modified cotton fabric and soak it with deionized water, the amount of Reactive Red 195 is 1% (owf), the bath ratio is 1:20, and the volume fraction of ethanol is 80%;

[0049] S2. Dye at room temperature, heat up to 40℃ at a heating rate of 2℃ / min, dye for 2h, add 2g / L sodium hydroxide, heat to 60℃, fix for 30min, then cool to 30℃ at a cooling rate of 5℃ / min, finish dyeing, wash with water, soap and dry.

[0050] Comparative Example 3 A dark dyeing process for water-saving cotton fabric comprises the following steps:

[0051] S1, take 3g cotton fabric and soak it with deionized water, use 1% (owf) of Reactive Red 195, bath ratio 1:20, add water to dissolve the dye, and then add 30g / L sodium chloride;

[0052] S2. Dye at room temperature, heat up to 40℃ at a heating rate of 2℃ / min, dye for 2h, add 2g / L sodium hydroxide, heat to 60℃, fix for 30min, then cool to 30℃ at a cooling rate of 5℃ / min, finish dyeing, wash with water, soap and dry.

[0053] Performance Testing

[0054] The cotton fabrics prepared in Examples 3-5 and Comparative Examples 1-3 were subjected to performance testing:

[0055] (1) K / S test: using the Kubelka-Munk function K / S = (1-R) 2 / 2R is used for calculation. Where: K is the absorption coefficient of the fabric under test; S is the scattering coefficient of the fabric under test; R is the inversion rate of the fabric under test at the wavelength of maximum absorption. The K / S value of the dyed fabric at the wavelength of maximum absorption is measured using a colorimeter. The larger the K / S value, the darker the color; the smaller the K / S value, the lighter the color. Each sample is tested 4 times in different parts, and the average value is taken to obtain the data results shown in Table 1.

[0056] (2) Dye uptake: The absorbance of the dye solution before and after dyeing was measured using a UV-visible spectrophotometer to calculate the dye uptake = (1-nA 1 / mA 0 )×100%, where: A 0 A is the absorbance of the dye solution diluted m times before staining; 1 The absorbance of the residual liquid after staining diluted n times, the data results are shown in Table 1.

[0057] (3) Color fastness test: According to GB / T 3920-2008 “Textiles - Tests for color fastness - Color fastness to rubbing”, the color fastness to rubbing of dyed cotton fabrics was measured using a rubbing color fastness tester; according to GB / T 3921-2008 “Textiles - Tests for color fastness - Color fastness to washing with soap”, the color fastness to washing with soap of dyed cotton fabrics was measured using a washing color fastness tester. The data results are shown in Table 1.

[0058] (4) Levelness test: The levelness of the fabric is evaluated based on the standard deviation of the apparent color depth between different test sites on the same dyed fabric. Eight different test sites are randomly selected on each dyed fabric for measurement, and the standard deviation of the K / S value is calculated. The data results are shown in Table 1.

[0059] Table 1 Sample performance test results

[0060]

[0061] From the data in Table 1, it can be seen that the cotton fabrics prepared in Examples 3-5 of the present invention have good dyeing properties and are uniformly dyed, and the color fastness and cotton staining fastness in the ethanol / water system reach level 4-5, and the dry rubbing fastness and wet rubbing fastness reach level 4-5, which is not significantly different from the water bath dyeing in Comparative Example 3, and the color fastness at all levels is excellent. In Comparative Example 1, the cotton fabric is not modified, and in Comparative Example 2, the reactive dye is not modified. It is measured that the dyeing properties of the cotton fabrics prepared in Comparative Examples 1-3 are worse than those of Examples 3-5.

[0062] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0063] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A dark dyeing process for water-saving cotton fabric, characterized in that: The following steps are involved: S1, taking cotton fabric and performing modification treatment to obtain modified cotton fabric; S2, soaking the modified cotton fabric with deionized water, the amount of modified reactive dye is 1-3%, the bath ratio is 1:20-40, and the volume fraction of ethanol is 80-90%; S3, dyeing at room temperature, heating up to 40~60℃ at a heating rate of 2~5℃ / min, dyeing for 1~2h, adding alkali, heating up to 60~90℃, fixing for 20~50min, then cooling down to 30~40℃ at a cooling rate of 2~5℃ / min, dyeing is completed, washing with water, soaping and drying; The method for preparing the modified cotton fabric in step S1 comprises the following steps: (1) placing the cotton fabric in an alkaline solution with a bath ratio of 1:50, wherein the mass fraction of sodium hydroxide is 20% and the volume fraction of ethanol is 40%, stirring the solution at 50-70°C for 1-2 hours, and then washing and drying the solution to obtain an alkaline-treated cotton fabric; (2) Soaking the alkalized cotton fabric in a modifier solution with a bath ratio of 1:50, wherein the mass fraction of sodium chloroacetate is 20% and the volume fraction of ethanol is 40%, and stirring the solution at 50-70°C for 1-2 hours. After the reaction is completed, the fabric is washed and dried, and then the excess alkali on the fabric is neutralized with an acetic acid solution to obtain a modified cotton fabric. The preparation method of the modified reactive dye in step S2 comprises the following steps: A. Add 2-hydroxymethylpyridine and 1-bromotetradecane to a reactor containing 1,4-dioxane solvent, place at 95-110° C. and stir for 36-48 hours. After the reaction is completed, rotary evaporate, wash, filter and dry to obtain a quaternary ammonium salt intermediate; B. Place the quaternary ammonium salt intermediate, the catalyst dibutyltin dilaurate, the inhibitor hydroquinone and anhydrous dichloromethane in a reactor, stir and dissolve at 30-35°C, then heat to 40-55°C, add isocyanoethyl methacrylate, stir and react for 4-8h, and after the reaction is completed, rotary evaporate, wash and dry to obtain a quaternary ammonium salt cationic modifier; C. Take a quaternary ammonium salt cationic modifier and add it to a reactor filled with deionized water, add methyl methacrylate and butyl acrylate in a nitrogen atmosphere, stir and react for 1-2 hours, heat to 75-90°C, keep warm for 5-10 minutes, then drop azobisisobutylamidine hydrochloride solution and react for 4-6 hours. After the reaction is completed, cool and filter to obtain a cationic microsphere dispersion; D. Take the active dye in the reactor, place it in a 25~30℃ water bath and slowly add the cationic microsphere dispersion dropwise for 1~1.5h. After the addition is completed, stir for 5~10min. Then adjust the pH value of the dye bath to 4~5 with hydrochloric acid, heat to 60~70℃ and dye for 2~3h. After the reaction is completed, cool to room temperature to obtain the modified active dye.

2. The dark dyeing process for water-saving cotton fabric according to claim 1, characterized in that: The mass ratio of 2-hydroxymethylpyridine to 1-bromotetradecane in step A is 1:5-5.

5.

3. The dark dyeing process for water-saving cotton fabric according to claim 1, characterized in that: In the step B, the mass ratio of the quaternary ammonium salt intermediate to isocyanoethyl methacrylate is 2-3:

1.

4. The dark dyeing process for water-saving cotton fabric according to claim 1, characterized in that: In the step C, the mass ratio of the quaternary ammonium salt cationic modifier, methyl methacrylate and butyl acrylate is 5-10:1-4:

1.

5. The dark dyeing process for water-saving cotton fabric according to claim 1, characterized in that: The concentration of the cationic microsphere dispersion in step D is 1-2 g / L, and the mass ratio of the reactive dye to the cationic microsphere dispersion is 0.08-1.2:

1.

6. The dark dyeing process for water-saving cotton fabric according to claim 1, characterized in that: The reactive dye is any one of CI Reactive Red 195, CI Reactive Yellow 95 and CI Reactive Blue 72.

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