A pre-dyeing and finishing process for nylon spandex fabric

Abstract

This application relates to the field of fabric processing technology, specifically disclosing a pre-treatment process for dyeing and finishing nylon-spandex fabrics. The pre-treatment process for nylon-spandex fabrics includes the following steps: adding a composite degreasing agent to the first and second washing tanks; pre-washing the fabric in the first and second washing tanks; and squeezing out the water. The composite degreasing agent comprises a first degreasing agent, a second degreasing agent, a chelating dispersant, and a co-solvent; the first degreasing agent comprises bis(3-aminopropyl)-terminated polydimethylsiloxane and dodecenyl succinic anhydride. Water is added to the third to sixth washing tanks; the pre-washed fabric is then washed in the third to sixth washing tanks respectively; after squeezing out the water, it is dried to obtain the final product. This pre-treatment process for nylon-spandex fabrics can gently and efficiently remove residual oil stains from the surface of nylon-spandex fabrics, thereby effectively improving the dyeing stability and dimensional stability of nylon-spandex fabrics during the dyeing and finishing process.

Description

Technical Field

[0001] This application relates to the field of fabric processing technology, and more specifically, it relates to a pre-treatment process for dyeing and finishing nylon spandex fabrics. Background Technology

[0002] With the popularization of healthy living concepts and the rise of athleisure trends, nylon-spandex fabrics have become an important choice for sportswear, casual fashion, and other fields due to their unique performance advantages. Nylon provides excellent abrasion resistance and strength, while spandex gives the fabric good elastic recovery and a close-fitting shaping effect, achieving a wearing experience that combines comfort and shaping.

[0003] In recent years, the requirements for nylon-spandex fabrics in various sports and leisure fields have been gradually increasing. The downstream market has put forward higher quality requirements for nylon-spandex fabrics in terms of color fastness and dimensional stability. At the same time, it has also required dyeing and finishing plants to upgrade and optimize their technology while providing high-quality fabrics in order to achieve green and low-carbon production processes.

[0004] Pretreatment is the first and crucial step in dyeing and finishing, aiming to remove natural impurities, oils, and sizing agents added during weaving from the fibers, laying the foundation for subsequent uniform dyeing and good finishing. However, the inventors have discovered that existing pretreatment processes for nylon-spandex fabrics mainly employ traditional alkaline desizing, high-temperature scouring, and conventional bleaching procedures. On the one hand, these processes cannot thoroughly and uniformly remove impurities from the fiber surface, especially dye-resistant substances such as spinning oils and weaving oils. These substances create barriers during subsequent dyeing, hindering the uniform penetration and fixation of dye molecules into the fiber interior, resulting in a significant decrease in the fabric's colorfastness to rubbing and washing. On the other hand, prolonged high-temperature treatment fails to consider the temperature sensitivity and shrinkage characteristics of nylon-spandex fabrics, damaging the fabric's elasticity and causing uneven tension during the dyeing stage, leading to severe fabric deformation and uneven dyeing. Summary of the Invention

[0005] To improve the dyeing and dimensional stability of nylon-spandex fabrics, this application provides a pre-treatment process for dyeing and finishing nylon-spandex fabrics.

[0006] This application provides a pre-treatment process for dyeing and finishing nylon-spandex fabrics, employing the following technical solution:

[0007] A pre-treatment process for dyeing and finishing nylon-spandex fabric includes the following steps:

[0008] S1: Add the composite degreasing agent to the first and second washing tanks, and pre-clean the fabric in the first and second washing tanks. After squeezing out the water, the pre-cleaned fabric is obtained. According to the mass concentration, the raw materials of the composite degreasing agent include 8-12 g / L of first degreasing agent, 2-4 g / L of second degreasing agent, 1-2 g / L of chelating dispersant and 2-4 g / L of cosolvent. The raw materials of the first degreasing agent include bis(3-aminopropyl)-terminated polydimethylsiloxane and dodecenyl succinic anhydride.

[0009] S2: Add water to the third to sixth washing tanks, and the pre-washed fabrics are washed in the third to sixth washing tanks respectively. After squeezing out the water, they are dried. After drying, the pre-treated fabrics are obtained.

[0010] By adopting the above technical solution, the inventors used the reaction product of bis(3-aminopropyl)-terminated polydimethylsiloxane and dodecenyl succinic anhydride as the first degreasing agent, which was combined with other components to form a composite degreasing agent. This agent can effectively penetrate and remove dyeing inhibitors such as spinning oil and weaving oil stains from the surface of nylon-spandex fabrics in a neutral and low-temperature environment. At the same time, it will not be re-deposited on the fabric surface during subsequent washing. Considering the sensitivity of nylon-spandex fabrics to temperature and acid and alkali and their tendency to shrink, this agent can improve the washing effect while maintaining the elasticity of the nylon-spandex fabric. This allows the fabric to be evenly dyed in subsequent dyeing and finishing processes, ensuring excellent dyeing stability and dimensional stability of the fabric.

[0011] The reaction between bis(3-aminopropyl)-terminated polydimethylsiloxane and dodecenyl succinic anhydride involves an amidation reaction between the two terminal amino groups in amino silicone oil and the anhydride ring, generating a long-chain dodecenyl group with a polydimethylsiloxane main chain and two carboxylic acid groups. This structure exhibits excellent dual hydrophilic and lipophilic properties. On one hand, the polydimethylsiloxane main chain is nonpolar with low surface tension, allowing it to be well-compatible with most spinning oils such as mineral oils, silicone oils, and fatty acids. It quickly spreads and anchors on the fiber and oily surfaces, penetrating and disrupting the adhesion interface between the oil and fiber, thus peeling off the oil from the fiber surface. On the other hand... On the one hand, the long oleophilic chains at both ends are compatible with the non-polar oil stain structure, acting as tentacles to penetrate deep into the oil stain, further enhancing the interaction between the degreasing agent molecules and hydrocarbon and ester oil stains, effectively encapsulating the oil stain particles. At the same time, they also have hydrophilic groups, forming a layer of hydrophilic interface film on the surface of the peeled oil stain, effectively preventing the re-aggregation of oil droplets, emulsifying large, water-insoluble oil stains into countless tiny, stable emulsion particles dispersed in the water. Under the mechanical force of water washing, the spinning oil, weaving oil stains and other dyeing inhibitors on the fibers are efficiently emulsified and dispersed into the aqueous phase and carried away by subsequent water washing.

[0012] Optionally, the preparation method of the first degreasing agent includes the following steps:

[0013] Under an inert gas atmosphere, bis(3-aminopropyl)-terminated polydimethylsiloxane, dodecenyl succinic anhydride and triethylamine are added to an organic solvent, stirred and heated to 80-90℃, reacted for 6-8 hours, then cooled to 40-50℃, stirred continuously, filtered to obtain crude product, and then distilled under reduced pressure to obtain the final product.

[0014] Optionally, the molar ratio of the bis(3-aminopropyl)-terminated polydimethylsiloxane to dodecenyl succinic anhydride is 1:(2.1-2.3).

[0015] Optionally, the first degreasing agent may be modified as follows:

[0016] Under an inert gas atmosphere, the first degreasing agent, ethylene glycol, and p-toluenesulfonic acid were added to an organic solvent, stirred and heated to react, then cooled, and the intermediate was obtained by vacuum distillation.

[0017] The intermediate was added to an organic solvent, and sulfur trioxide-pyridine complex was added dropwise at a molar ratio of 1:(2.05-2.15) under ice-water bath and stirring. After the addition was completed, the reaction was stirred to obtain a reaction solution.

[0018] The reactants were added to ice water, then neutralized with sodium bicarbonate solution, and then the modified first degreasing agent was obtained by vacuum distillation, dialysis, and a second vacuum distillation.

[0019] By adopting the above technical solution, the inventors first alcoholized the carboxyl groups on the lipophilic long chains at both ends of the reaction product of bis(3-aminopropyl)-terminated polydimethylsiloxane and dodecenyl succinic anhydride, and then sulfated them through the reaction of sulfur trioxide-pyridine complex with alcohol to obtain sulfate salt. This modification treatment not only retains but also enhances the hydrophilicity of the first degreasing agent, resulting in higher hydration energy and a larger hydration layer in aqueous solution. This significantly reduces the surface tension of water, allowing for faster removal of the detached oil stains into the water, forming a finer and more stable emulsion for more thorough pre-washing. Furthermore, the sulfate groups are less likely to precipitate with calcium and magnesium ions in water, effectively preventing the redeposition of insoluble soap scum onto the fabric and improving the uniformity of subsequent fabric dyeing. Simultaneously, under neutral conditions, it exhibits stronger electrostatic repulsion with nylon and spandex fibers, resulting in stronger anti-re-adhesion and a more thorough cleaning effect.

[0020] Optionally, the fabric is pre-cleaned with a compound degreasing agent in the first and second washing tanks at a temperature of 40-50°C.

[0021] Optionally, the temperature of the fabric being washed in the third and sixth washing tanks is 55-65°C.

[0022] Optionally, the second degreasing agent is sodium linear dodecylbenzenesulfonate.

[0023] By adopting the above technical solution, sodium dodecylbenzenesulfonate with a shorter carbon chain is selected as an anionic emulsifier and used in combination with the first degreasing agent. A balance is achieved between water solubility and interfacial adsorption strength, forming a denser and stronger mixed interfacial film. It can also further enhance the electrostatic repulsion and steric hindrance effect between the emulsified liquid and nylon spandex fibers, and more efficiently emulsify oil stains into stable micro-droplets, which are then carried away by the water flow during random washing.

[0024] Optionally, the co-solvent is sodium isopropylbenzenesulfonate.

[0025] By adopting the above technical solution and using sodium isopropylbenzenesulfonate as a water-soluble growth promoter, the solubility of nonionic and anionic surfactants can be effectively improved, ensuring that the composite degreasing agent is evenly dispersed in the cleaning solution, avoiding excessively high local concentrations or precipitation, and improving degreasing efficiency.

[0026] In summary, this application has the following beneficial effects:

[0027] 1. Because this application uses the reaction of bis(3-aminopropyl)-terminated polydimethylsiloxane and dodecenyl succinic anhydride to obtain a first degreasing agent with dual hydrophilic and oleophilic properties, with polydimethylsiloxane chain as the main chain and hydrophilic groups at both ends, it can be well compatible with most mineral oils, hydrocarbons and esters and other spinning oils in a low-temperature and neutral environment. It can quickly spread and anchor on the surface of fibers and oil stains, penetrate and destroy the adhesion interface between oil stains and fibers, and peel off the oil from the fiber surface. At the same time, a layer of hydrophilic interface film is formed on the surface of the peeled oil stains, which effectively prevents the re-aggregation of oil droplets. It emulsifies large oil stains that are insoluble in water into countless tiny, stable emulsion particles dispersed in water. Under the mechanical force of water washing, the spinning oil, weaving oil stains and other dyeing agents on the fibers are efficiently emulsified and dispersed into the aqueous phase and carried away by subsequent water washing.

[0028] 2. In this application, the first degreasing agent is further modified by introducing sulfate esters onto the lipophilic long-chain dodecenyl chains at both ends. This not only further promotes the first degreasing agent to pull the encapsulated and detached oil stains into the water more quickly, forming a finer and more stable emulsion for random washing and more thorough pre-cleaning, but also effectively enhances the mutual repulsion between the emulsified and dispersed oil droplets and the nylon and spandex fibers in a neutral environment, resulting in stronger anti-re-adhesion and a more thorough cleaning effect.

[0029] 3. This application uses a 6-section washing machine to achieve continuous and efficient washing under low temperature and neutral conditions. It is more environmentally friendly and energy-saving, while also achieving a more thorough oil removal effect. It effectively protects the elasticity and dimensional stability of nylon and spandex fabrics, increases the dyeing success rate, and effectively reduces the occurrence of color spots, color variations, and white spots in subsequent dyeing and finishing processes, resulting in higher color fastness. Detailed Implementation

[0030] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0031] raw material

[0032] Unless otherwise specified, all raw materials used in the embodiments and comparative examples in this application are commercially available products, specifically:

[0033] This nylon-spandex fabric is made by twisting 70D / 48F nylon yarn with 40D spandex yarn in both the warp and weft directions. The warp density is 425 threads / 10cm, and the weft density is 250 threads / 10cm. It is woven in a twill weave and has a weight of 308g / m². 2 ;

[0034] Dodecenylsuccinic anhydride, CAS: 25377-73-5;

[0035] Bis(3-aminopropyl)-terminated polydimethylsiloxane, selected from Suzhou Qitian New Material Co., Ltd., CAS: 106214-84-0;

[0036] Sulfur trioxide-pyridine complex, analytical grade, CAS: 26412-87-3;

[0037] Sodium linear dodecylbenzenesulfonate, CAS: 25155-30-0;

[0038] Branched dodecylbenzene sulfonate, CAS: 69669-44-9;

[0039] Sodium tetradecylbenzenesulfonate, CAS: 1797-33-7;

[0040] Chelating dispersant, selected from Transfar Intelligent Equipment Co., Ltd., chelating dispersant TF-133H;

[0041] Acidic leveling agent, selected from Jiangmen Xinhui District Xianyi Chemical Technology Co., Ltd., QY-202;

[0042] The water softener is selected from Jiangmen Xinhui District Qianyi Chemical Technology Co., Ltd., and is a phosphate-free water softener.

[0043] Yuzhongbao, selected from Yiyang Daxin New Materials Co., Ltd., DX-949.

[0044] Example of preparation of first degreasing agent

[0045] Preparation Example 1

[0046] The first degreasing agent is prepared by the following steps:

[0047] Under a nitrogen atmosphere, 1 mol of bis(3-aminopropyl)-terminated polydimethylsiloxane, 2.1 mol of dodecenylsuccinic anhydride, and 2.15 mol of triethylamine were added to dichloromethane at a feed-to-liquid ratio of 1:2. The mixture was stirred at 250 rpm and heated to 90°C. The reaction was carried out at a constant temperature for 6 hours, then cooled to 50°C and stirred for another hour. The crude product was obtained by filtration and then subjected to vacuum distillation to obtain the final product.

[0048] Preparation Example 2

[0049] The first degreasing agent is prepared by the following steps:

[0050] Under a nitrogen atmosphere, 1 mol of bis(3-aminopropyl)-terminated polydimethylsiloxane, 2.2 mol of dodecenylsuccinic anhydride, and 2.2 mol of triethylamine were added to dichloromethane at a feed-to-liquid ratio of 1:2. The mixture was stirred at 250 rpm and heated to 85°C. The reaction was carried out at this temperature for 7 hours, then cooled to 45°C and stirred for another 0.5 hours. The crude product was obtained by filtration and then subjected to vacuum distillation to obtain the final product.

[0051] Preparation Example 3

[0052] The first degreasing agent is prepared by the following steps:

[0053] Under a nitrogen atmosphere, 1 mol of bis(3-aminopropyl)-terminated polydimethylsiloxane, 2.3 mol of dodecenylsuccinic anhydride, and 2.25 mol of triethylamine were added to dichloromethane at a feed-to-liquid ratio of 1:2. The mixture was stirred at 250 rpm and heated to 80°C. The reaction was carried out at a constant temperature for 8 hours, then cooled to 40°C and stirred for another hour. The crude product was obtained by filtration and then subjected to vacuum distillation to obtain the final product.

[0054] Preparation Example 4

[0055] The modified first degreasing agent is prepared by the following steps:

[0056] S1: Under a nitrogen atmosphere, 1 mol of the first degreasing agent prepared in Preparation Example 1, 2.5 mol of ethylene glycol and 0.05 mol of p-toluenesulfonic acid were added to toluene at a ratio of 1:3. The mixture was stirred and heated to 110°C for 10 h, then cooled and distilled under reduced pressure to obtain the intermediate.

[0057] S2: Add the intermediate to toluene, and add sulfur trioxide-pyridine complex dropwise at a molar ratio of 1:2.05 under ice-water bath and stirring conditions. The amount of toluene is 3 times the total amount of reactants. Keep the system temperature ≤5℃. After the dropwise addition is completed, continue stirring for 3 hours to obtain the reaction solution.

[0058] S3: Add the reactants to 5 times their volume of ice water, then add 10% sodium bicarbonate solution, stir to neutralize thoroughly, adjust the pH of the mixture to 7±0.5, and then obtain the modified first degreasing agent by vacuum distillation, dialysis, and secondary vacuum distillation.

[0059] Preparation Example 5

[0060] The modified first degreasing agent is prepared by the following steps:

[0061] S1: Under a nitrogen atmosphere, 1 mol of the first degreasing agent prepared in Preparation Example 2, 2.5 mol of ethylene glycol and 0.05 mol of p-toluenesulfonic acid were added to toluene at a ratio of 1:3. The mixture was stirred and heated to 120°C for 8 hours, then cooled and distilled under reduced pressure to obtain the intermediate.

[0062] S2: Add the intermediate to toluene, and add sulfur trioxide-pyridine complex dropwise at a molar ratio of 1:2.1 under ice-water bath and stirring conditions. The amount of toluene is 3 times the total amount of reactants. Keep the system temperature ≤5℃. After the dropwise addition is completed, continue stirring for 2 hours to obtain the reaction solution.

[0063] S3: Add the reactants to 5 times their volume of ice water, then add 10% sodium bicarbonate solution, stir to neutralize thoroughly, adjust the pH of the mixture to 7±0.5, and then obtain the modified first degreasing agent by vacuum distillation, dialysis, and secondary vacuum distillation.

[0064] Preparation Example 6

[0065] The modified first degreasing agent is prepared by the following steps:

[0066] S1: Under a nitrogen atmosphere, 1 mol of the first degreasing agent prepared in Preparation Example 3, 2.5 mol of ethylene glycol and 0.05 mol of p-toluenesulfonic acid were added to toluene at a ratio of 1:3. The mixture was stirred and heated to 120°C for 9 hours, then cooled and distilled under reduced pressure to obtain the intermediate.

[0067] S2: Add the intermediate to toluene, and add sulfur trioxide-pyridine complex dropwise at a molar ratio of 1:2.15 under ice-water bath and stirring conditions. The amount of toluene used is 3 times the total amount of reactants. Keep the system temperature ≤5℃. After the dropwise addition is completed, continue stirring for 3 hours to obtain the reaction solution.

[0068] S3: Add the reactants to 5 times their volume of ice water, then add 10% sodium bicarbonate solution, stir to neutralize thoroughly, adjust the pH of the mixture to 7±0.5, and then obtain the modified first degreasing agent by vacuum distillation, dialysis, and secondary vacuum distillation. Example Example 1

[0069] A pre-treatment process for dyeing and finishing nylon-spandex fabric includes the following steps:

[0070] S1: The first degreasing agent prepared in Preparation Example 1, sodium linear dodecylbenzenesulfonate, chelating dispersant, sodium isopropylbenzenesulfonate and water are mixed and stirred evenly to obtain a composite degreasing agent.

[0071] S2: The washing process is set using a 6-section washing machine. A composite degreasing agent is added to the first and second washing tanks, which, according to the mass concentration, includes 10.2 g / L of the first degreasing agent prepared in Preparation Example 1, 3.1 g / L of linear dodecylbenzene sulfonate, 1.5 g / L of chelating dispersant and 3 g / L of sodium isopropylbenzene sulfonate. Clean water is added to the third to sixth washing tanks.

[0072] S3: The nylon spandex fabric is fed into the first washing tank at a conveying speed of 30m / min for a first pre-washing. The liquid temperature of the first washing tank is 40℃. After the water is squeezed out by 2.5MPa rollers, the pre-washed fabric is obtained. Then it is fed into the second washing tank for a second pre-washing. The liquid temperature of the second washing tank is 50℃. After the water is squeezed out by 2.5MPa rollers, the pre-washed fabric is obtained.

[0073] S4: The pre-cleaned fabric is placed into the third to sixth washing tanks for cleaning. The liquid temperatures of the third to sixth washing tanks are 55, 65, 60 and 55℃ respectively. After the water is squeezed out by 2.5MPa rollers, the fabric is dried at a low temperature of 50℃ to obtain the pre-treated fabric. Example 2

[0074] A pre-treatment process for dyeing and finishing nylon-spandex fabric includes the following steps:

[0075] S1: The first degreasing agent prepared in Preparation Example 1, sodium linear dodecylbenzenesulfonate, chelating dispersant, sodium isopropylbenzenesulfonate and water are mixed and stirred evenly to obtain a composite degreasing agent.

[0076] S2: The washing process is set using a 6-section washing machine. A composite degreasing agent is added to the first and second washing tanks, which includes 8 g / L of the first degreasing agent prepared in Preparation Example 1, 2 g / L of linear dodecylbenzene sulfonate, 1 g / L of chelating dispersant and 2 g / L of sodium isopropylbenzene sulfonate according to the mass concentration. Clean water is added to the third to sixth washing tanks.

[0077] S3: The nylon spandex fabric is fed into the first washing tank at a conveying speed of 30m / min for a first pre-washing. The liquid temperature of the first washing tank is 40℃. After the water is squeezed out by 2.5MPa rollers, the pre-washed fabric is obtained. Then it is fed into the second washing tank for a second pre-washing. The liquid temperature of the second washing tank is 50℃. After the water is squeezed out by 2.5MPa rollers, the pre-washed fabric is obtained.

[0078] S4: The pre-cleaned fabric is placed into the third to sixth washing tanks for cleaning. The liquid temperatures of the third to sixth washing tanks are 55, 65, 60 and 55℃ respectively. After the water is squeezed out by 2.5MPa rollers, the fabric is dried at a low temperature of 50℃ to obtain the pre-treated fabric. Example 3

[0079] A pre-treatment process for dyeing and finishing nylon-spandex fabric includes the following steps:

[0080] S1: The first degreasing agent prepared in Preparation Example 1, sodium linear dodecylbenzenesulfonate, chelating dispersant, sodium isopropylbenzenesulfonate and water are mixed and stirred evenly to obtain a composite degreasing agent.

[0081] S2: The washing process is set using a 6-section washing machine. A composite degreasing agent is added to the first and second washing tanks, which includes 12 g / L of the first degreasing agent prepared in Preparation Example 1, 4 g / L of linear dodecylbenzene sulfonate, 2 g / L of chelating dispersant and 4 g / L of sodium isopropylbenzene sulfonate according to the mass concentration. Clean water is added to the third to sixth washing tanks.

[0082] S3: The nylon spandex fabric is fed into the first washing tank at a conveying speed of 30m / min for a first pre-washing. The liquid temperature of the first washing tank is 40℃. After the water is squeezed out by 2.5MPa rollers, the pre-washed fabric is obtained. Then it is fed into the second washing tank for a second pre-washing. The liquid temperature of the second washing tank is 50℃. After the water is squeezed out by 2.5MPa rollers, the pre-washed fabric is obtained.

[0083] S4: The pre-cleaned fabric is placed into the third to sixth washing tanks for cleaning. The liquid temperatures of the third to sixth washing tanks are 55, 65, 60 and 55℃ respectively. After the water is squeezed out by 2.5MPa rollers, the fabric is dried at a low temperature of 50℃ to obtain the pre-treated fabric. Example 4

[0084] A pre-treatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that the first degreasing agent in the composite degreasing agent is prepared in Preparation Example 2, while the other steps are the same as in Example 1. Example 5

[0085] A pre-treatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that the first degreasing agent in the composite degreasing agent is prepared by Preparation Example 3, while the other steps are the same as in Example 1. Example 6

[0086] A pre-treatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that the first degreasing agent in the composite degreasing agent is replaced with an equal mass of the modified first degreasing agent prepared in Preparation Example 4, while the other steps are the same as in Example 1. Example 7

[0087] A pretreatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that the first degreasing agent in the composite degreasing agent is replaced with an equal mass of the modified first degreasing agent prepared in Preparation Example 5, while the other steps are the same as in Example 1. Example 8

[0088] A pretreatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that the first degreasing agent in the composite degreasing agent is replaced with an equal mass of the modified first degreasing agent prepared in Preparation Example 6, while the other steps are the same as in Example 1. Example 9

[0089] A pre-treatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that the linear sodium dodecylbenzene sulfonate in the composite degreasing agent is replaced with an equal mass of branched sodium dodecylbenzene sulfonate; all other steps are the same as in Example 1. Example 10

[0090] A pre-treatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that sodium linear dodecylbenzene sulfonate in the composite degreasing agent is replaced with an equal mass of sodium linear tetradecylbenzene sulfonate; all other steps are the same as in Example 1. Comparative Example

[0091] Comparative Example 1

[0092] A pre-treatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that the first degreasing agent is not added to the composite degreasing agent, while the other steps are the same as in Example 1.

[0093] Comparative Example 2

[0094] A pre-treatment process for dyeing and finishing nylon spandex fabric differs from Example 1 in that no second degreasing agent is added to the composite degreasing agent, while the other steps are the same as in Example 1.

[0095] Comparative Example 3

[0096] A pre-treatment process for dyeing and finishing nylon spandex fabrics differs from Example 1 in that the first degreasing agent in the composite degreasing agent is replaced with an equal mass of refining degreasing agent TF-115K (selected from Transfar Smart Logistics Co., Ltd.), while the other steps are the same as in Example 1.

[0097] Performance testing

[0098] The nylon-spandex pretreated fabrics obtained by the dyeing and finishing pretreatment processes of Examples 1-10 and Comparative Examples 1-3 were added to a dyeing machine for the same dyeing and finishing treatment. The dyes included 2.64% dye, 1 g / L acid leveling agent, 1 g / L ammonium sulfate, 1 g / L bath conditioner and 2 g / L water softener. After drying and setting at 60℃ for 40 min, the fabrics were dried at 90℃ for 20 min to obtain the nylon-spandex fabric. The following related tests were then performed, and the test results are recorded in Table 1.

[0099] 1. Wet rubbing fastness: According to GB / T 3920-2008 "Textiles - Tests for color fastness - Color fastness to rubbing", the color change gray scale is used for rating;

[0100] 2. Wash fastness: Refer to GB / T 3921.3 "Textiles - Tests for color fastness - Wash fastness: Experiment 3", and use the gray scale for assessing color change to rate the color fastness.

[0101] 3. Breaking strength: The test was conducted in accordance with the relevant provisions of GB / T 3923.1-1997 "Textiles - Determination of tensile properties of fabrics - Partial breaking and elongation at break". Each test was performed 3 times, and the average value of the 3 test results was taken as the final result and recorded in Table 1.

[0102] 4. Elastic elongation: The test was conducted in accordance with the relevant provisions of FZ / T 70006-2004 "Test Method for Tensile Elastic Recovery of Knitted Fabrics". Each group of tests was performed 3 times, and the average value of the 3 test results was taken as the final result and recorded in Table 1.

[0103] Table 1

[0104]

[0105] According to the performance test results of Examples 1-5 and Comparative Example 3 in Table 1, it can be seen that the composite degreasing agent used in this application for the pretreatment of nylon and spandex fabrics after dyeing and finishing maintains a high level of breaking strength and elastic elongation. This indicates that under the pretreatment process of this application, the composite degreasing agent can effectively peel off and disperse different types of spinning oils such as mineral oils, hydrocarbons and esters on the surface of spandex and nylon fibers and remove them with water washing in a neutral and low temperature environment. The dyeing wet rubbing and washing fastness of the fabric maintain a high level, and will not adversely affect the mechanical and elastic properties of the fiber itself, and the dimensional stability is also better.

[0106] According to the performance test results of Example 1 and Comparative Example 1, it can be seen that the first degreasing agent with dual hydrophilic and oleophilic properties, obtained by reacting bis(3-aminopropyl)-terminated polydimethylsiloxane and dodecenyl succinic anhydride, has a polydimethylsiloxane chain as the main chain and hydrophilic groups at both ends. It can quickly spread and anchor on the surface of fibers and oil stains in a low-temperature and neutral environment, penetrate and destroy the adhesion interface between oil stains and fibers, and peel off the oil agent from the fiber surface. At the same time, a layer of hydrophilic interface film is formed on the peeled oil stain surface, which effectively prevents the re-aggregation of oil droplets. It emulsifies large oil stains that are insoluble in water into countless tiny, stable emulsion particles dispersed in water. Under the mechanical force of water washing, the spinning oil agent, weaving oil stains and other dyeing inhibitors on the fibers are efficiently emulsified, dispersed into the aqueous phase and carried away by subsequent water washing.

[0107] According to the performance test results of Examples 1, 4-5 and 6-8, it can be seen that the fabric obtained by pre-treatment with the modified first degreasing agent formed by introducing sulfate esters into the oleophilic long-chain dodecenyl chains at both ends of the first degreasing agent has significantly improved wet rubbing color fastness and washing color fastness after dyeing and finishing treatment. The mechanical properties and elastic properties are also better than those of the fabric obtained after pre-treatment with the unmodified degreasing agent. This is because the modification treatment of the first degreasing agent not only enhances its hydrophilicity, giving it higher hydration energy and a hydration layer in aqueous solution, but also further reduces the surface tension of water, allowing it to more quickly pull the peeled oil stains into the water, emulsifying them into a finer and more stable emulsion for subsequent random washing. This makes the pre-cleaning more thorough. Furthermore, the sulfate ester groups are less likely to precipitate with calcium and magnesium ions in water, effectively preventing the redeposition of insoluble soap scum onto the fabric and improving the uniformity of subsequent fabric dyeing. At the same time, under neutral conditions, it has a stronger electrostatic repulsion effect with nylon and spandex fibers, resulting in stronger anti-re-adhesion and a more thorough cleaning effect.

[0108] According to the performance test results of Examples 1, 9-10 and Comparative Example 2, when sodium alkylbenzene sulfonate with a linear structure is compounded with the first degreasing agent, the micelles and interfacial films formed are more dense than those with a branched structure, resulting in a stronger synergistic emulsification effect. In contrast, sodium tetradecylbenzene sulfonate has an excessively long chain length and strong oleophilicity, leading to poor water solubility and migration rate. Under low temperature and neutral conditions, sodium dodecylbenzene sulfonate can form a faster and more effective synergistic effect with the first degreasing agent, resulting in a stronger anti-staining effect and a more thorough cleaning effect, thus laying a good foundation for uniform dyeing and the preparation of high-quality fabrics.

[0109] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A pre-treatment process for dyeing and finishing nylon-spandex fabrics, characterized in that, Includes the following steps: S1: Add the composite degreasing agent to the first and second washing tanks, and pre-clean the fabric in the first and second washing tanks. After squeezing out the water, the pre-cleaned fabric is obtained. According to the mass concentration, the raw materials of the composite degreasing agent include 8-12 g / L modified first degreasing agent, 2-4 g / L second degreasing agent, 1-2 g / L chelating dispersant and 2-4 g / L cosolvent. The preparation method of the modified first degreasing agent includes the following steps: under an inert gas atmosphere, bis(3-aminopropyl)-terminated polydimethylsiloxane, dodecenyl succinic anhydride and triethylamine are added to an organic solvent, stirred and heated to 80-90℃, reacted for 6-8 hours, then cooled to 40-50℃, stirred continuously, filtered to obtain a crude product, and then distilled under reduced pressure to obtain the first degreasing agent. The first degreasing agent is then modified by sulfation esterification. Under an inert gas atmosphere, the first degreasing agent is reacted with ethylene glycol and p-toluenesulfonic acid... The mixture was added to an organic solvent, stirred and heated to react, then cooled, and distilled under reduced pressure to obtain an intermediate. The intermediate was added to the organic solvent, and sulfur trioxide-pyridine complex was added dropwise at a molar ratio of 1:(2.05-2.15) under stirring in an ice-water bath. After the addition was complete, the reaction was stirred to obtain a reaction solution. The reaction solution was added to ice water, then neutralized with sodium bicarbonate solution, and then obtained by reduced pressure distillation, dialysis, and a second reduced pressure distillation to obtain the modified first degreasing agent. The second degreasing agent was linear dodecylbenzene sulfonate sodium. S2: Add water to the third to sixth washing tanks, and pre-clean the fabric is placed into the third to sixth washing tanks for cleaning. After squeezing out the water, it is dried to obtain the pre-treated fabric. The temperature of the fabric pre-cleaned with the compound degreasing agent in the first and second washing tanks is 40-50℃, and the temperature of the water cleaning in the third and sixth washing tanks is 55-65℃.

2. The pre-dyeing and finishing process for nylon-spandex fabrics according to claim 1, characterized in that, The molar ratio of the bis(3-aminopropyl)-terminated polydimethylsiloxane to dodecenyl succinic anhydride is 1:(2.1-2.3).

3. The pre-dyeing and finishing process for nylon-spandex fabrics according to claim 1, characterized in that, The co-solvent is sodium isopropylbenzenesulfonate.

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