Salt-free and water-less dyeing method suitable for cotton knitted fabric

Abstract

The invention belongs to the technical field of dyeing and finishing processing, and particularly discloses a salt-free and water-less dyeing method suitable for cotton knitted fabrics, which is characterized by comprising the following steps: preparing a product to be dyed, preparing a special dyeing system, dyeing, soaping and drying, adding edible oil to prepare a special chromosome system. The edible oil is one or more of soybean oil, rapeseed oil, castor oil, corn oil, peanut oil, sunflower seed oil, olive oil and salad oil. According to the method, no accelerating salt is needed, the reactive dye can be quickly dyed to the surface of the cotton fiber by means of the edible oil which is insoluble in water, and in an environment with less water and less alkaline agent, the hydrolysis of the dye is greatly reduced, and the fixation rate of the dye is greatly improved. According to the dyeing method, the utilization rate of the reactive dye for dyeing the cotton knitted fabric is effectively increased, the dyed cotton knitted fabric does not need to be subjected to color fixation treatment, and the wet rubbing fastness meets the market requirement.

Description

Technical Field

[0001] This invention belongs to the field of dyeing and finishing technology, and relates to a salt-free and low-water dyeing method suitable for cotton knitted fabrics. Background Technology

[0002] As the economy and society shift from high-speed development to high-quality development, the requirements for manufacturing production are becoming increasingly stringent, with wastewater discharge being a particular focus of public concern. Cotton knitwear, due to its natural properties and comfortable wearing conditions, has always been popular. In textile production and processing, cotton knitwear has consistently accounted for a large proportion and is an important component of dyeing and finishing processes.

[0003] Traditional dyeing methods for cotton knitted fabrics include overflow dyeing and warp beam dyeing. Both methods involve a water bath and require the addition of large amounts of inorganic salts to overcome the electrostatic repulsion between the dye and cotton fibers, thereby increasing the dye uptake rate. During the fixation process, alkali agents are added to induce nucleophilic substitution or nucleophilic addition reactions between the reactive dyes and the cotton fibers. However, reactive dyes have high solubility in water, resulting in a significant amount of dye residue remaining in the aqueous solution after dyeing. Furthermore, in an alkaline environment, reactive dyes are prone to hydrolysis, leading to a large amount of floating dye on the fiber surface. Subsequent processes require substantial amounts of water to remove this floating dye, ensuring the fabric's colorfastness meets market demands. The majority of dyeing wastewater originates from washing wastewater; a single dyeing and finishing process consumes 100 tons of water per ton of cotton textiles, of which 80 tons are washing wastewater. Therefore, dyeing and finishing industry professionals have been continuously searching for new dyeing processes and post-treatment auxiliaries to improve the fixation rate and wash fastness of reactive dyes while reducing water consumption in the washing process. To achieve salt-free dyeing of cotton knitwear, researchers developed a cationic modification technique for cotton fibers. This involves cationically modifying the cotton fabric before dyeing, giving the cotton fibers a positive charge. During dyeing, the anionic reactive dyes attract the cationic cotton fibers electrostatically, enabling salt-free dyeing of cotton knitwear. However, this dyeing system still operates in a water bath, resulting in a relatively low fixation rate for the reactive dyes (50%-65%). Multiple washes are still required to meet the required colorfastness.

[0004] This application is submitted in response to the above-mentioned issues. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a salt-free and low-water dyeing method suitable for cotton knitted fabrics.

[0006] The purpose of this invention is to provide a salt-free and low-water dyeing method suitable for cotton knitted fabrics, including preparing the product to be dyed, configuring a special dyeing system, dyeing, soaping, and drying. The configuration of the special dyeing system is as follows: stirring the reactive dye and alkali solution evenly in water, adding edible oil to configure the special dyeing system, wherein the mass ratio of the edible oil to the product to be dyed is 1:(8-20), and the mass of the water is 1-2 times the mass of the product to be dyed.

[0007] Preferably, the product to be dyed is a cotton knitted fabric, and the alkaline solution is one or more of sodium hydroxide, potassium hydroxide, sodium acetate, sodium methoxide, and potassium ethoxide.

[0008] Preferably, the reactive dye is 0.5%-10% (owf), and the alkaline solution is 0.5%-20% (owf).

[0009] Preferably, the reactive dye is one or more of the following: triazine dye, vinyl sulfone dye, dual reactive group reactive dye, and multi-reactive group reactive dye.

[0010] Preferably, the reactive dye is one or more of the dual reactive group reactive dyes.

[0011] Preferably, the edible oil is one or more of soybean oil, rapeseed oil, castor oil, corn oil, peanut oil, sunflower seed oil, olive oil, and salad oil.

[0012] Preferably, the edible oil is one or two of soybean oil, corn oil, sunflower seed oil, and salad oil.

[0013] Preferably, the dyeing process specifically involves: loading the product to be dyed and the special dyeing system into a dyeing vat, controlling the temperature in the dyeing vat between 50-90℃, and maintaining the temperature for 30-120 minutes.

[0014] Preferably, the soaping agent is a neutral soaping agent, with a dosage of 0.5-5 g / L, a bath ratio of 1:(5-30), a soaping temperature of 40-90℃, a soaping time of 10-30 min, and a subsequent hot water wash at 40-80℃ for 10-30 min.

[0015] Using the above technical solution, the neutral soap detergent is a mixture, and its main component is a surfactant, such as sodium dodecylbenzenesulfonate, sodium dodecyl polyoxyethylene ether sulfate, sodium dodecyl sulfate, polyoxyethylene ether, and other surfactants.

[0016] Preferably, the drying process specifically involves drying the dyed product at 50-80°C to obtain the dyed product.

[0017] Using the above technical solution, the dyeing system in this process consists of three parts: cotton knitted fabric, a high-concentration reactive dye aqueous solution (20-100 g / L), and edible oil. The dyeing system contains cotton knitted fabric, edible oil, and a reactive dye / alkali solution. In the dyeing system, the edible oil is hydrophobic, while cotton is hydrophilic. During the dyeing process, because the hydrophilic dye is completely insoluble in non-aqueous media, yet has a high affinity for the cotton fabric itself, the dye has a strong tendency to abandon the medium and favor the cotton fabric, meaning that the dye distribution rate on the fabric has an absolute advantage compared to the edible oil. Therefore, a high dyeing rate can be achieved without any dyeing salts. In a water bath, the dyeing environment is entirely water, and the dye is soluble in water. Compared to cotton fabric, reactive dyes are more likely to remain in water. Furthermore, reactive dyes are anionic, and cotton fibers are also negatively charged, resulting in electrostatic repulsion between them. Therefore, adding a large amount of inorganic salt during the dyeing process alters the electrostatic repulsion between the dye and the fiber, thereby improving the dyeing rate.

[0018] The beneficial effects of this invention are: (1) The dyeing method of the present invention does not require any dyeing salt. With the help of water-immiscible edible oil, reactive dyes can be quickly applied to the surface of cotton fibers. Moreover, in an environment with little water and little alkali, the hydrolysis of dyes is greatly reduced, which greatly improves the dye fixation rate. This dyeing method not only effectively improves the utilization rate of reactive dyes for dyeing cotton knitted fabrics, but also eliminates the need for color fixing treatment after dyeing, and the wet rubbing fastness meets market demands.

[0019] (2) The process used in this invention consumes less water. Compared with traditional water bath dyeing of cotton knitted fabrics, it can save more than 80% of water. Therefore, the method generates less wastewater and is green and environmentally friendly. During the dyeing process, there is no salt and little alkali, which greatly reduces the hydrolysis of reactive dyes. The fixation rate of reactive dyes is more than 90%. The dyeing medium used is non-toxic, odorless and degradable. After dyeing, it can be recycled and reused after simple static separation. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0021] This invention provides a salt-free, low-water dyeing method suitable for cotton knitted fabrics, including preparing the product to be dyed, configuring a special dyeing system, dyeing, soaping, and drying. The special dyeing system is configured by stirring reactive dye and alkali solution evenly in water, adding edible oil to form the special dyeing system, and the mass ratio of edible oil to the product to be dyed is 1:(8-20) (non-limiting examples, such as 1:8, 1:10, 1:12, 1:15, 1:20, etc.), and the mass of water is 1-2 times the mass of the product to be dyed (non-limiting examples, such as 1, 1.2, 1.5, 1.8, 2, etc.).

[0022] In some embodiments, the product to be dyed is a cotton knitted fabric, and the alkaline solution is one or more of sodium hydroxide, potassium hydroxide, sodium acetate, sodium methoxide, and potassium ethoxide.

[0023] In some embodiments, the reactive dye is 0.5%-10% (owf) (non-limiting examples, such as 0.5% (owf), 1% (owf), 2% (owf), 3% (owf), 4% (owf), 5% (owf), 6% (owf), 7% (owf), 8% (owf), 9% (owf), 10% (owf), etc.), and the alkaline solution is 0.5%-20% (owf) (non-limiting examples, such as 0.5% (owf), 1% (owf), 3% (owf), 5% (owf), 7% (owf), 10% (owf), 12% (owf), 15% (owf), 18% (owf), 20% (owf), etc.).

[0024] In some embodiments, the reactive dye is one or more of the following: triazine dye, vinyl sulfone dye, dual reactive group reactive dye, and multi-reactive group reactive dye.

[0025] In some embodiments, the reactive dye is one or more of a dual-reactive-group reactive dye.

[0026] In some embodiments, the edible oil is one or more of soybean oil, rapeseed oil, castor oil, corn oil, peanut oil, sunflower seed oil, olive oil, and salad oil.

[0027] In some embodiments, the edible oil is one or two of soybean oil, corn oil, sunflower seed oil, and salad oil.

[0028] In some embodiments, the dyeing process specifically involves: loading the product to be dyed and the special dyeing system into a dyeing vat, controlling the temperature in the dyeing vat between 50-90°C, and maintaining the temperature for 30-120 minutes.

[0029] In some embodiments, the soaping agent is a neutral soaping agent, with a dosage of 0.5-5 g / L, a bath ratio of 1:(5-30), a soaping temperature of 40-90℃, a soaping time of 10-30 min, and a subsequent hot water wash at 40-80℃ for 10-30 min.

[0030] In some embodiments, drying specifically involves drying the dyed product at 50-80°C to obtain the dyed product.

[0031] Example 1: A salt-free, low-water dyeing method suitable for cotton knitted fabrics, comprising the following steps: S1: Prepare the product to be dyed: Prepare 1kg of pure cotton fabric to be dyed; S2: Prepare a special dyeing system: Dissolve 3% (owf) Reactive Black 5 and 6.5% (owf) sodium carbonate in 1.2 kg of aqueous solution, stir well, and add 10 kg of corn oil to prepare a special dyeing system; S3: Dyeing: Put the cotton knitted fabric and the special dyeing system into the dyeing vat, circulate for 15 minutes, then raise the temperature to 50℃ at 2℃ / min and keep it at that temperature for 60 minutes. S4: Soap washing: Soap washing uses soap flakes, dosage 2g / L, bath ratio 1:10, soap washing temperature 90℃, soap washing time 20min, followed by soap washing with 60℃ hot water for 20min. S5: Drying: Dry the dyed cotton knitted fabric at 80℃ to obtain the dyed product.

[0032] Example 2: A salt-free, low-water dyeing method suitable for cotton knitted fabrics, comprising the following steps: S1: Prepare the products to be dyed; prepare 3kg of undyed cotton knitwear; S2: Prepare a special dyeing system: Dissolve 2% (owf) Red 120 and 2.5% (owf) sodium hydroxide in 3.0 kg of aqueous solution, stir well, and add 24 kg of sunflower seed oil to prepare a special dyeing system; S3: Dyeing: Put the cotton knitted fabric and the special dyeing system into the dyeing vat, circulate for 15 minutes, then raise the temperature to 80℃ at 1℃ / min and keep it at that temperature for 60 minutes. S4: Soap washing: Soap washing uses soap flakes, dosage 3g / L, bath ratio 1:8, soap washing temperature 90℃, soap washing time 15min, followed by soap washing with 60℃ hot water for 20min. S5: Drying: Dry the dyed cotton knitted fabric at 60℃ to obtain the dyed product.

[0033] Example 3: A salt-free, low-water dyeing method suitable for cotton knitted fabrics, comprising the following steps: S1: Prepare the product to be dyed; prepare 1 kg of undyed cotton knitwear; S2: Prepare a special dyeing system: Dissolve 3% (owf) Red 195, 2.5% (owf) sodium carbonate and 0.5% (owf) sodium hydroxide in 1.5 kg of aqueous solution, stir well, and add 12 kg of olive oil to prepare a special dyeing system; S3: Dyeing: Put the cotton knitted fabric and the special dyeing system into the dyeing vat, circulate for 15 minutes, then raise the temperature to 65℃ at 1℃ / min and keep it at that temperature for 55 minutes. S4: Soap washing: Soap washing uses soap flakes, dosage 3g / L, bath ratio 1:8, soap washing temperature 90℃, soap washing time 15min, followed by soap washing with 60℃ hot water for 20min. S5: Drying: Dry the dyed cotton knitted fabric at 60℃ to obtain the dyed product.

[0034] Example 4: A salt-free, low-water dyeing method suitable for cotton knitted fabrics, comprising the following steps: S1: Prepare the products to be dyed; prepare 3kg of undyed cotton knitwear; S2: Prepare a special dyeing system: Dissolve 3% (owf) Red 120 and 10.5% (owf) sodium carbonate in 5.4 kg of aqueous solution, stir well, and add 45 kg of mixed oil (olive oil and sunflower seed oil in a 1:1 mass ratio) to prepare a special dyeing system; S3: Dyeing: Put the cotton knitted fabric and the special dyeing system into the dyeing vat, circulate for 15 minutes, then raise the temperature to 80℃ at 1℃ / min and keep it at that temperature for 60 minutes. S4: Soap washing: Soap washing uses soap flakes, dosage 3g / L, bath ratio 1:8, soap washing temperature 90℃, soap washing time 15min, followed by soap washing with 60℃ hot water for 20min. S5: Drying: Dry the dyed cotton knitted fabric at 60℃ to obtain the dyed product.

[0035] Example 5: A salt-free, low-water dyeing method suitable for cotton knitted fabrics, comprising the following steps: S1: Prepare the products to be dyed; prepare 25kg of undyed cotton knitwear; S2: Prepare a special dyeing system: Dissolve 2% (owf) Black 5, 0.89% (owf) Red 195, 1.5% (owf) sodium carbonate and 0.8% (owf) sodium hydroxide in 50kg of aqueous solution, stir well, and add 300kg of soybean oil to prepare a special dyeing system; S3: Dyeing: Put the cotton knitted fabric and the special dyeing system into the dyeing vat, circulate for 15 minutes, then raise the temperature to 65℃ at 1℃ / min and keep it at that temperature for 55 minutes. S4: Soap washing: Soap washing uses soap flakes, dosage 3g / L, bath ratio 1:8, soap washing temperature 90℃, soap washing time 15min, followed by soap washing with 60℃ hot water for 20min. S5: Drying: Dry the dyed cotton knitted fabric at 60℃ to obtain the dyed product.

[0036] Comparative Example 1 differs from Example 5 in that the mass of water in step S2 is 62.5 kg, otherwise it is the same as Example 5.

[0037] Comparative Example 2, Traditional Water Bath Dyeing Method, S1: Prepare the product to be dyed; prepare 3 kg of undyed cotton knitwear; S2: Prepare a special staining system: Add 2% (owf) Red 120 to 75kg (liquor ratio 1:15) of water; S3: Dyeing: Put the cotton knitted fabric into the dyeing vat, circulate for 15 minutes, add 1.50 kg of sodium sulfate, circulate for 15 minutes, add another 1.50 kg of sodium sulfate, circulate for 15 minutes, then raise the temperature to 50℃ at 1℃ / min and keep it at that temperature for 30 minutes. S4: Fixing: Heat to 80℃ at 1℃ / min, add 1.12kg of sodium carbonate, and keep warm for 60min.

[0038] S5: Soap washing: Soap washing uses soap flakes, dosage 3g / L, bath ratio 1:15, soap washing temperature 90℃, soap washing time 15min, followed by soap washing with 60℃ hot water for 20min. S6: Drying: Dry the washed cotton knitted fabric to obtain the dyed product.

[0039] The cotton knitted fabric obtained by dyeing in Comparative Example 2 was red, with a K / S value of 12.45, a dyeing rate of 68.49%, a fixation rate of 61.43%, a dry rubbing fastness of grade 5, a wet rubbing fastness of grade 4, and a washing fastness of grade 3-4.

[0040] In Experiment 1, the products obtained from Examples 1-5 and Comparative Example 1 were subjected to performance tests, and the results are detailed in Table 1.

[0041] Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Color fixation rate 92.72% 94.52% 91.22% 92.92% 91.62% 82.69% K / S value 23.54 16.91 19.67 19.14 25.67 19.25 Color difference (ΔE) value 0.86 0.94 0.56 0.39 0.29 0.21 wet friction fastness Level 4 Level 4 Level 3-4 Level 3-4 Level 4 Level 4 Wash fastness Level 4 Level 4 Level 4 Level 4-5 Level 4-5 Level 4-5 As can be seen from Table 1, when the amount of water in step S2 is 1-2 times the mass of the product to be dyed, the fixation rate is above 91.22%. In Comparative Example 1, the amount of water in step S2 is 2.5 times the mass of the product to be dyed, and the fixation rate is obviously reduced. Therefore, the preferred amount of water in step S2 of this invention is 1-2 times the mass of the product to be dyed.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0043] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A salt-free, low-water dyeing method suitable for cotton knitted fabrics, characterized in that, The process includes preparing the product to be dyed, configuring a special dyeing system, dyeing, soaping, and drying. The configuration of the special dyeing system is as follows: the reactive dye and the alkali solution are stirred evenly in water, and edible oil is added to prepare the special dyeing system. The mass ratio of the edible oil to the product to be dyed is 1:(8-20), and the mass of the water is 1-2 times the mass of the product to be dyed.

2. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 1, characterized in that, The product to be dyed is a cotton knitted fabric, and the alkaline solution is one or more of sodium hydroxide, potassium hydroxide, sodium acetate, sodium methoxide, and potassium ethoxide.

3. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 2, characterized in that, The reactive dye is 0.5%-10% (owf), and the alkaline solution is 0.5%-20% (owf).

4. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 3, characterized in that, The reactive dye is one or more of the following: triazine dye, vinyl sulfone dye, dual reactive group reactive dye, and multi-reactive group reactive dye.

5. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 4, characterized in that, The reactive dye is one or more of the dual reactive group reactive dyes.

6. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 1, characterized in that, The edible oil is one or more of the following: soybean oil, rapeseed oil, castor oil, corn oil, peanut oil, sunflower seed oil, olive oil, and salad oil.

7. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 6, characterized in that, The edible oil is one or two of soybean oil, corn oil, sunflower seed oil, and salad oil.

8. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 1, characterized in that, The dyeing process specifically involves: placing the product to be dyed and the special dyeing system into a dyeing vat, controlling the temperature in the dyeing vat between 50-90℃, and maintaining the temperature for 30-120 minutes.

9. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 1, characterized in that, The soaping agent is a neutral soaping agent, with a dosage of 0.5-5 g / L, a bath ratio of 1:(5-30), a soaping temperature of 40-90℃, a soaping time of 10-30 min, and a subsequent hot water wash at 40-80℃ for 10-30 min.

10. The salt-free, low-water dyeing method for cotton knitted fabrics as described in claim 1, characterized in that, The drying process specifically involves drying the dyed product at 50-80℃ to obtain the dyed product.