Bleaching, alkali decrement and whitening one-bath process for polyester fabric

Abstract

The invention belongs to the technical field of textile processing, and particularly relates to a bleaching, alkali decrement and whitening one-bath process for polyester fabric. The polyester fabric bleaching, alkali decrement and whitening one-bath process comprises the following steps: in an overflow cylinder, keeping the nozzle pressure at 1.8-2.2 MPa, the pump speed at 35-40Hz, the cloth speed at 250-300m / min and the bath ratio at 1: (10-15), carrying out bleaching, alkali decrement and whitening one-bath treatment on the singed and deoiled polyester fabric by adopting a working solution, and then washing and drying; the working solution comprises a whitening agent, an alkaline agent, a bleaching agent, a chelating dispersant and a hydrogen peroxide stabilizer. According to the bleaching, alkali decrement and whitening one-bath process for the polyester fabric, the problems that in an existing process, the number of procedures is large, the treatment time is long, and the quality of a finished product is unstable are solved; meanwhile, the treated fabric is high in whiteness, soft in hand feeling and high in cost performance.

Description

Technical Field

[0001] This invention belongs to the field of textile processing technology, specifically relating to a one-bath process for bleaching, alkali reduction, and whitening of polyester fabrics. Background Technology

[0002] Alkali reduction treatment of polyester fibers is a key technology that uses hot alkali solution to carry out controlled hydrolytic etching on the fiber surface. This process can give the fiber a soft feel and excellent drape. The process will peel off the fiber surface layer to varying degrees, exposing new crystalline areas and potentially forming micropores and cracks.

[0003] This treatment has a dual impact on subsequent whitening processes: on the one hand, the newly formed surface is cleaner, which is conducive to the adsorption and penetration of fluorescent whitening agents, and theoretically can improve whiteness; on the other hand, the complexity of the surface structure (such as roughening and micropore formation) will lead to enhanced light scattering, which may allow some whitening agents to enter the fiber interior, forming microscopic defects and causing "light loss", thereby weakening the apparent whiteness and brilliance; in addition, the differences in concentration, temperature and time of the alkali reduction process will lead to inconsistent fiber surface morphology, further increasing the volatility and control difficulty of the whitening process.

[0004] CN112779762A proposes a bleaching and whitening method for polyester-cotton composite yarn fabrics. For a polyester-nylon composite yarn fabric with 80% polyester and 20% nylon, the process involves guiding the fabric through a guide, sewing, rinsing, pretreatment, and alkali reduction treatment, followed by oxygen bleaching. After washing and acid neutralization to adjust the pH, a whitening process is then carried out. Subsequently, residual auxiliaries are removed through segmented washing, and finally, a softening treatment is performed to obtain the finished product. The entire process effectively removes fabric pigments and impurities, improves whiteness, and ensures color uniformity by controlling the reaction conditions of bleaching and whitening in stages, while maintaining the original strength of the fabric, thus meeting the requirements for bleaching and whitening effects. However, this method is a typical three-step alkali reduction-oxygen bleaching-whitening method, which is lengthy and has cumbersome process connections, resulting in low production efficiency.

[0005] CN103668842A discloses a production process for bleached fabric resembling silk. First, the fabric undergoes pre-forming treatment to lay the foundation for subsequent processing. Then, an alkali reduction treatment is performed, adding caustic soda, oligomer removers, scouring agents, and bath softeners. After multiple rounds of washing, acetic acid neutralization, and antistatic agent treatment, the fabric is removed from the vat to improve its hand feel and performance. Next, the fabric is dehydrated and dried to remove moisture for subsequent processes. Then, polyester brighteners, antistatic agents, and softeners are added in a setting machine for whitening treatment to enhance the fabric's whiteness. Finally, calendering optimizes the fabric's appearance and texture. In this process, the alkali reduction and whitening processes are performed independently. The surface structure of the fibers changes after alkali reduction, necessitating the introduction of multiple auxiliaries to ensure the product's hand feel. Summary of the Invention

[0006] To overcome the aforementioned defects in the existing technology, the purpose of this invention is to provide a one-bath process for bleaching, alkali reduction, and whitening polyester fabrics, which solves the problems of multiple steps, long processing time, and unstable finished product quality in the existing process; at the same time, the treated fabric has high whiteness, soft hand feel, and high cost performance.

[0007] The one-bath process for bleaching, alkali reduction, and whitening of polyester fabrics described in this invention involves maintaining a nozzle pressure of 1.8-2.2 MPa, a pump speed of 35-40 Hz, a fabric speed of 250-300 m / min, and a bath ratio (mass ratio of polyester fabric to working solution) of 1:(10-15) in an overflow tank. The working solution is used to perform a one-bath treatment of bleaching, alkali reduction, and whitening on the singeed and degreased polyester fabric, followed by washing and drying. The working solution includes a whitening agent, an alkali agent, a bleaching agent, a chelating dispersant, and a hydrogen peroxide stabilizer. Specifically, the hydrogen peroxide stabilizer is 5-10 g / L, the alkali agent is 10-25 g / L, the chelating dispersant is 1-5 g / L, and the bleaching agent is 5-15 g / L. The amount of whitening agent used is 0.1-1.0% of the mass of the polyester fabric, and the pH of the working solution is 10-14.

[0008] The brightening agent is a dicyandiamide-based alkali-resistant fluorescent brightening agent, specifically UVITEX. ® EVB, UVITEX ® One or two of EBBs, preferably UVITEX ® EVB and UVITEX ® EBB is a mixture of UVITEX and EBB in a 1:1 mass ratio. ® EVB and UVITEX ® All EBBs were purchased from Huntsman Textiles & Chemicals (China) Co., Ltd.

[0009] The bleaching agent is 27.5 wt.% hydrogen peroxide, the alkali agent is 37.2 wt.% liquid alkali, the hydrogen peroxide stabilizer is OUR-266, purchased from Nantong Aor Industry & Trade Co., Ltd., and the chelating dispersant is Raytexil SQ-N, purchased from Zibo Lurui Fine Chemical Co., Ltd.

[0010] The process of bleaching, alkali reduction, and whitening in a single bath is as follows: Increase the temperature at a rate of 1-3℃ / min to 40-50℃ and hold for 5-15 minutes. Then, continue to increase the temperature at a rate of 1-3℃ / min to 110℃-140℃ and hold for 60-100 minutes. After holding, cool down to below 80℃ and discharge the residual liquid.

[0011] The washing process is as follows: the polyester fabric after bleaching, alkali reduction and whitening one-bath treatment is washed in stages to pH 6-8. The first stage of washing is at a temperature of 75-80℃ and is washed for 10-20 minutes; the second stage of washing is at a temperature of 75-80℃ and is washed for 10-20 minutes; the third stage of washing is at a temperature of 55-65℃ and is washed for 10-20 minutes.

[0012] The polyester fabric is one of the following: woven polyester fabric, knitted polyester fabric, or yarn-dyed pure polyester fabric.

[0013] Preferably, the one-bath process for bleaching, alkali reduction, and whitening of the polyester fabric is carried out using one of the following steps: polyester woven fabric, polyester knitted fabric, or yarn-dyed pure polyester fabric. After singeing and degreasing, the polyester fabric is placed in an overflow machine containing working solution for a one-bath treatment of bleaching, alkali reduction, and whitening. The nozzle pressure is maintained at 1.8-2.2 MPa, the pump speed at 35-40 Hz, the fabric speed at 250-300 m / min, and the liquor ratio at 1:(10-15). The temperature is increased to 40-50℃ at a rate of 1-3℃ / min and held for 5-15 min. Subsequently, the temperature is increased to 110℃-140℃ at a rate of 1-3℃ / min and held for 60-100 min. After the holding period, the treatment is completed. Cool the fabric to below 80℃ and wash it in stages with clean water. The first stage wash temperature is 75-80℃, and the wash time is 10-20 minutes. The second stage wash temperature is 75-80℃, and the wash time is 10-20 minutes. The third stage wash temperature is 55-65℃, and the wash time is 10-20 minutes. The pH of the washing solution is 7±1. After washing, dry the fabric to obtain the product. The working solution contains: OUR-266 at 5-10 g / L, 37.2 wt.% liquid alkali at 15-25 g / L, Raytexil SQ-N at 3-5 g / L, and 27.5 wt.% hydrogen peroxide at 10-15 g / L. The amount of whitening agent is 0.5-1.0% of the weight of the polyester fabric, and the pH of the working solution is 12-14.

[0014] The present invention provides a one-bath process for bleaching, alkali reduction, and whitening polyester fabrics. This process utilizes 37.2 wt.% liquid alkali to provide a strong alkaline environment, causing controlled hydrolytic etching of the polyester fiber surface under high temperature conditions. This removes the fiber surface layer and forms a microporous structure, giving the fabric a soft feel and good drape. Simultaneously, other components in the one-bath system buffer the strong alkaline effect, preventing excessive fiber hydrolysis and controlling strength loss. Furthermore, after alkali reduction, the microstructure of the polyester fibers becomes looser. While the pigments on the fiber surface and inside are oxidized and destroyed by hydrogen peroxide, the fluorescent whitening agent molecules can penetrate and adsorb into the fiber interior more quickly and evenly, resulting in uniform whiteness of the fabric after the one-bath treatment.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The polyester fabric bleaching, alkali reduction and whitening one-bath process of the present invention realizes bleaching, alkali reduction and whitening one-bath processing, which saves water significantly, shortens the total processing time, improves equipment utilization, and reduces the loss of auxiliaries and processes. At the same time, after simplifying the process, the repeated friction of the fabric between the machines is reduced, which effectively reduces the generation of physical defects such as wrinkles, abrasions and curling edges.

[0016] (2) The polyester fabric bleaching, alkali reduction and whitening one-bath process of the present invention uses whitening agent and bleaching agent at the same time as alkali reduction treatment, so that the whitening agent can be uniformly penetrated and adsorbed, avoiding the problem of uneven whitening. The finished product has higher whiteness, purer color and stronger stability. The fabric also has a soft hand feel. At the same time, the one-bath system can buffer the strong alkali effect and prevent excessive loss of fiber strength. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below. Unless otherwise specified, the raw materials and instruments used in this invention are all commercially available, and unless otherwise specified, the processes adopted are conventional processes.

[0018] The raw materials are described below: 37.2 wt.% liquid alkali: Qilu Branch of China Petroleum & Chemical Corporation; 27.5 wt.% hydrogen peroxide: Shandong Minghua New Materials Co., Ltd.; Hydrogen peroxide stabilizer OUR-266: Nantong Aor Industry & Trade Co., Ltd.; Chelating dispersant Raytexil SQ-N: Zibo Lurui Fine Chemical Co., Ltd.; UVITEX ® EVB, UVITEX ® EBB: Huntsman Textiles & Dyes (China) Co., Ltd.

[0019] Example 1 The one-bath process for bleaching, alkali reduction, and whitening of the polyester fabric uses fabrics with the following specifications: T30×P300D×97×70×61 / 62, warp yarns: 30-count polyester staple fiber (English count); weft yarns: 300 denier polyester filament; density: 97 warp ends / inch, 70 weft ends / inch; width: 61-62 inches; blend ratio: 100% polyester; weave: plain weave, and the following steps are performed: The polyester fabric, after singeing and degreasing, was placed in an overflow machine containing the working solution for a one-bath treatment of bleaching, alkali reduction, and whitening. The nozzle pressure was maintained at 2.15 MPa, the pump speed at 38 Hz, the fabric speed at 286 m / min, and the liquor ratio at 1:15. The temperature was increased to 45°C at a rate of 2°C / min and held for 10 min. Subsequently, the temperature was increased to 130°C at a rate of 2°C / min and held for 90 min. After the holding period, the temperature was lowered to 75°C, and the polyester fabric was washed in stages with clean water. The first stage was washed at 80°C for 10 min; the second stage was washed at 80°C for 10 min; and the third stage was washed at 60°C for 10 min. The pH of the washing solution was 7±1. After washing, the fabric was dried to obtain the product. The working solution contained: OUR-266 5 g / L, 37.2 wt.% liquid alkali 18 g / L, and Raytexil. SQ-N is 3 g / L, 27.5 wt.% hydrogen peroxide is 10 g / L; UVITEX ® EVB and UVITEX ® The EBB dosage was 0.5% of the polyester fabric mass, and the working solution pH was 13.5.

[0020] Example 2 The one-bath process for bleaching, alkali reduction, and whitening of the polyester fabric uses fabrics with the following specifications: T14×T14×115×80×59 / 60, warp yarns: 14-count polyester staple fiber (English count); weft yarns: 14-count polyester staple fiber (English count); density: 115 warp ends / inch, 80 weft ends / inch; width: 59-60 inches; blend ratio: 100% polyester; weave: plain weave. The fabric is processed using the following steps: The polyester fabric, after singeing and degreasing, was placed in an overflow machine containing the working solution for a one-bath treatment of bleaching, alkali reduction, and whitening. The nozzle pressure was maintained at 1.8 MPa, the pump speed at 35 Hz, the fabric speed at 250 m / min, and the liquor ratio at 1:10. The temperature was increased to 40°C at a rate of 3°C / min and held for 15 min. Subsequently, the temperature was increased to 110°C at a rate of 1°C / min and held for 100 min. After the holding period, the temperature was lowered to 75°C, and the polyester fabric was washed in stages with clean water. The first stage was washed at 75°C for 20 min; the second stage was washed at 75°C for 15 min; and the third stage was washed at 55°C for 20 min. The pH of the washing solution was 7±1. After washing, the fabric was dried to obtain the product. The working solution contained: OUR-266 at 8 g / L, 37.2 wt.% liquid alkali at 15 g / L, and Raytexil. SQ-N is 4 g / L, 27.5 wt.% hydrogen peroxide is 12 g / L; UVITEX ® EVB and UVITEX ® The EBB dosage was 0.3% of the polyester fabric mass, and the working solution pH was 12.

[0021] Example 3 The one-bath process for bleaching, alkali reduction, and whitening of the polyester fabric uses fabrics with the following specifications: P200D×P200D×130×95×57 / 58, warp yarns: 200 denier polyester filament; weft yarns: 200 denier polyester filament; density: warp density 130 ends / inch, weft density 95 ends / inch; width: 57-58 inches; blend ratio: 100% polyester; weave: 2 / 2 twill, and is processed as follows: The polyester fabric, after singeing and degreasing, was placed in an overflow machine containing the working solution for a one-bath treatment of bleaching, alkali reduction, and whitening. The nozzle pressure was maintained at 2.2 MPa, the pump speed at 40 Hz, the fabric speed at 280 m / min, and the liquor ratio at 1:12. The temperature was increased to 50°C at a rate of 1°C / min and held for 5 min. Then, the temperature was increased to 140°C at a rate of 3°C / min and held for 60 min. After the holding period, the temperature was lowered to 75°C, and the polyester fabric was washed in stages with clean water. The first stage was washed at 80°C for 15 min; the second stage was washed at 80°C for 20 min; and the third stage was washed at 65°C for 15 min. The pH of the washing solution was 7±1. After washing, the fabric was dried to obtain the product. The working solution contained: OUR-266 10 g / L, 37.2 wt.% liquid alkali 25 g / L, and Raytexil. SQ-N is 5 g / L, 27.5 wt.% hydrogen peroxide is 15 g / L; UVITEX ® EVB and UVITEX ® The EBB dosage was 0.4% of the polyester fabric mass, and the working solution pH was 14.

[0022] Comparative Example 1 The difference from Example 1 is that bleaching, alkali reduction, and whitening are performed in three-bath processes, as detailed below: (1) Bleaching process: In the working solution, H2O2: 10g / L, OUR-266: 5g / L, Raytexil SQ-N: 3g / L; bleaching temperature 130℃, bleaching time 20min; (2) Alkali reduction process: 37.2wt.% liquid alkali: 18g / L; alkali reduction temperature 130℃, time 90min; (3) Whitening process: UVITEX ® EVB and UVITEX ® The EBB dosage was 0.5% of the polyester fabric mass, the temperature was 130°C, and the time was 20 min; other steps were the same as in Example 1.

[0023] Comparative Example 2 The difference from Example 1 is that alkali reduction is a separate process, while whitening and bleaching are performed in the same process. The specific process is as follows: (1) Alkali reduction process: 37.2wt.% liquid alkali: 18g / L; alkali reduction temperature 130℃, time 90min; (2) Bleaching and whitening process: H2O2: 10g / L, OUR-266: 5g / L, Raytexil SQ-N: 3g / L, UVITEX ® EVB and UVITEX ® The EBB dosage was 0.5% of the polyester fabric mass, the temperature was 130°C, and the time was 20 min; other steps were the same as in Example 1.

[0024] Comparative Example 3 Same as Example 1, except that no bleaching agent and hydrogen peroxide stabilizer are added to the working solution, while the other raw materials and processes are the same as in Example 1.

[0025] Comparative Example 4 Same as Example 1, except that the whitening agent UVITEX is used. ® EVB and UVITEX ® EBB replaced with the whitening agent Leucophor ® BCR (stilbene derivative), the other raw materials and processes are the same as in Example 1.

[0026] Comparative Example 5 Same as Example 1, except that the chelating dispersant Raytexil SQ-N was not added, while the other raw materials and processes are the same as in Example 1.

[0027] The products prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to performance tests. The test results are shown in Table 1. The hand feel was determined by a comprehensive evaluation after repeated touching by 10 people. The whiteness of the fabric before and after washing was tested using a Datacolor spectrophotometer with a D65 light source, in accordance with the washing method of GB / T 8629-2017.

[0028] Table 1 Comparison of Fabric Performance

[0029] As can be seen from Table 1, the product prepared in the example has a smooth and delicate feel and good comfort; the whiteness is basically the same as that of the traditional multi-bath process; and the whiteness reduction is small after 20 washes, with excellent whiteness retention; with only 1 processing step, compared with the traditional multi-bath process of Comparative Example 1 and Comparative Example 2, the process is greatly simplified and the total processing time is shortened.

[0030] Compared with Example 1, Comparative Example 3 lacked hydrogen peroxide and hydrogen peroxide stabilizer, so the pigments and impurities were not effectively removed. Even if the whitening agents (UVITEX®EVB, UVITEX®EBB) could be normally adsorbed and penetrated, the apparent whiteness would decrease due to pigment interference. Furthermore, residual impurities would affect the binding stability of the whitening agents and fibers, making the whitening agents more likely to fall off during washing, resulting in a greater decrease in whiteness after washing.

[0031] Compared to Example 1, Comparative Example 4 replaced the whitening agent in Example 1 with Leucophor® BCR (stilbene derivative), while keeping other conditions unchanged. The finished product had a similar feel to Example 1, but the whiteness of the finished product was only 148, and after 20 washes, the whiteness dropped to 140, a significant decrease. The whiteness and whiteness retention after washing were far inferior to Example 1, which used a dicyandiamide-based alkali-resistant fluorescent whitening agent. The reason is that in a strongly alkaline environment with pH ≥ 12, the double bonds in the Leucophor® BCR molecule are prone to hydrolysis and breakage, resulting in the destruction of the fluorescent emission structure and the failure of the core function. At the same time, the adsorption force between the hydrolyzed molecules and polyester fibers decreases, and even if some molecules are not hydrolyzed, they are easily detached during washing, resulting in a significant decrease in whiteness after washing.

[0032] Compared with Example 1, Comparative Example 5 lacks the chelating dispersant Raytexil SQ-N in its working solution, resulting in uneven dispersion of the whitening agent. This leads to excessively high or low concentrations of the whitening agent in certain areas, which in turn reduces the whiteness. Furthermore, the whitening agent molecules may aggregate in the working solution, and the fiber surface may be partially covered by oligomers, preventing the whitening agent from being adsorbed. The whitening agent is easily detached during washing, resulting in a large decrease and significant fluctuation in whiteness after washing.

Claims

1. A one-bath process for bleaching, alkali reduction, and whitening polyester fabrics, characterized in that, In the overflow tank, the polyester fabric after singeing and degreasing is bleached, alkali reduced and whitened in one bath using working liquid, and then washed and dried. The working solution comprises a whitening agent, an alkali agent, a bleaching agent, a chelating dispersant, and a hydrogen peroxide stabilizer. Specifically, the working solution contains: 5-10 g / L of hydrogen peroxide stabilizer, 10-25 g / L of alkali agent, 1-5 g / L of chelating dispersant, and 5-15 g / L of bleaching agent. The amount of whitening agent used is 0.1-1.0% of the polyester fabric mass, and the pH of the working solution is 10-14. The whitening agent is a dicyandiamide-based alkali-resistant fluorescent whitening agent.

2. The one-bath process for bleaching, alkali reduction, and whitening polyester fabrics according to claim 1, characterized in that, Dicyanophthalic acid-styrene-based alkali-resistant fluorescent whitening agents include UVITEX. ® EVB, UVITEX ® One or two of the EBBs.

3. The one-bath process for bleaching, alkali reduction, and whitening polyester fabrics according to claim 1, characterized in that, The bleaching agent is 27.5 wt.% hydrogen peroxide, and the alkali agent is 37.2 wt.% liquid alkali.

4. The one-bath process for bleaching, alkali reduction, and whitening polyester fabrics according to claim 1, characterized in that, In the working solution, the hydrogen peroxide stabilizer is OUR-266, and the chelating dispersant is Raytexil SQ-N.

5. The one-bath process for bleaching, alkali reduction, and whitening polyester fabrics according to claim 1, characterized in that, The process of bleaching, alkali reduction, and whitening in a single bath is as follows: Increase the temperature to 40-50℃ at a rate of 1-3℃ / min, hold for 5-15 minutes, then continue to increase the temperature to 110℃-140℃ at a rate of 1-3℃ / min, hold for 60-100 minutes, and after holding, cool down to below 80℃ and discharge the residual liquid.

6. The one-bath process for bleaching, alkali reduction, and whitening polyester fabrics according to claim 1, characterized in that, The washing process is as follows: After bleaching, alkali reduction and whitening one-bath treatment, the polyester fabric is washed in stages until the pH value is 6-8. The first stage of washing is at a temperature of 75-80℃ and is washed for 10-20 minutes; the second stage of washing is at a temperature of 75-80℃ and is washed for 10-20 minutes; the third stage of washing is at a temperature of 55-65℃ and is washed for 10-20 minutes.

7. The one-bath process for bleaching, alkali reduction, and whitening polyester fabrics according to claim 1, characterized in that, The operating parameters of the overflow cylinder are: nozzle pressure 1.8-2.2MPa, pump speed 35-40Hz, cloth speed 250-300m / min, and bath ratio 1:(10-15).

8. The one-bath process for bleaching, alkali reduction, and whitening polyester fabrics according to claim 1, characterized in that, Polyester fabrics are one of the following: woven polyester fabrics, knitted polyester fabrics, and yarn-dyed pure polyester fabrics.

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