Method for degreasing and bleaching cotton fibers

Abstract

The invention provides a cotton fiber degreasing and bleaching method, and belongs to the technical field of fiber degreasing and bleaching. The method for degreasing and bleaching the cotton fibers comprises the steps that the cotton fibers are placed in an ethanol-water solution of sodium hydroxide to be padded, and first cotton fibers are obtained; uniformly spraying an ethanol solution of hydrogen peroxide on the first cotton fibers, and rolling to obtain second cotton fibers; steaming the second cotton fibers to obtain third cotton fibers; washing the third cotton fiber in an ethanol-water mixed solution, and rolling to obtain a fourth cotton fiber; and carrying out ozone treatment on the fourth cotton fiber, washing and drying to obtain the degreased and bleached cotton fiber. According to the method, ethanol and ozone are cooperatively used, so that the bleaching effect is improved, the use of salt, alkali and chemical additives is effectively reduced, and the consumption of water resources is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fiber degreasing and bleaching, and particularly relates to a method for degreasing and bleaching cotton fibers. BACKGROUND

[0002] Fibers must be degreased and bleached before being made into clothes to meet the requirements of clothes. At present, the method for degreasing and bleaching cotton fibers is mostly to realize degreasing and bleaching by using high-concentration alkali-oxygen solution cold pad-batch or low-concentration alkali-oxygen solution high-temperature cooking and bleaching. In the process of degreasing and bleaching, a large amount of salt, alkali and other chemical auxiliaries are discharged into the natural environment, which pollutes the environment. At the same time, a large amount of water is needed to wash the chemical drugs remaining on the fibers during the degreasing and bleaching process and after the degreasing and bleaching, which consumes a large amount of water resources.

[0003] Therefore, it is necessary to provide an improved method for degreasing and bleaching cotton fibers to solve the above problems. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a method for degreasing and bleaching cotton fibers, which effectively reduces the use of salt, alkali and chemical auxiliaries and reduces the consumption of water resources while improving the bleaching effect by using ethanol and ozone synergistically.

[0005] The present application provides a method for degreasing and bleaching cotton fibers, which comprises the following steps: S1. Immersing cotton fibers in an ethanol-water solution of sodium hydroxide to obtain first cotton fibers; S2. Spraying an ethanol solution of hydrogen peroxide uniformly on the first cotton fibers to obtain second cotton fibers after rolling; S3. Steaming the second cotton fibers to obtain third cotton fibers; S4. Washing the third cotton fibers in an ethanol-water mixed solution to obtain fourth cotton fibers after rolling; S5. Ozone treatment of the fourth cotton fibers, and obtaining degreased and bleached cotton fibers after washing and drying.

[0006] In the technical solution of the embodiment of the present application, by first padding the cotton fibers in an ethanol-water solution of sodium hydroxide, the ethanol in the solution can be used to promote the wetting of the cotton fibers and the penetration of the sodium hydroxide, so that the surface and interior of the first cotton fibers obtained after padding are loaded with a large amount of sodium hydroxide. Subsequently, spraying the ethanol solution of hydrogen peroxide can further promote the penetration of hydrogen peroxide into the cotton fibers and improve the stability of hydrogen peroxide. In addition, hydrogen peroxide can play a good degreasing and bleaching role in the presence of sodium hydroxide. Then, steaming can be performed to make the cotton fiber surface smoother and flatter. In the present application, by first washing the cotton fibers in an ethanol-water mixed solution after steaming, the cotton fibers can be fully loaded with ethanol. Then, ozone treatment can be performed, which can achieve a synergistic effect between ethanol and ozone, using ethanol to promote faster ozone penetration into the fiber interior, while allowing the ozone to oxidize the hydroxyl groups in the ethanol into hydroxyl radicals, further enhancing its bleaching effect. In addition, the hydrophilic groups such as carboxyl groups generated by the oxidation of ethanol can reduce the polarity of the fiber surface, further improving the hydrophilicity of the fiber. Based on the technical solution provided in the embodiments of the present application, the use of salt, alkali and chemical additives can be effectively reduced while improving the bleaching effect, and the consumption of water resources can be reduced.

[0007] In some embodiments, in step S4, the volume ratio of ethanol to water in the ethanol-water mixed solution is 9:1 to 5:5.

[0008] In this embodiment, the cotton fibers are washed with an ethanol-water mixed solution and the proportion of ethanol is regulated so that the washed cotton fibers are evenly loaded with an appropriate amount of ethanol, so as to synergize with the subsequent ozone treatment to improve the bleaching effect.

[0009] In some embodiments, in step S4, the liquid carrying rate after rolling is 100% to 200%. In this embodiment, by controlling the liquid carrying rate after rolling, it is possible to ensure that the cotton fibers are loaded with an appropriate amount of ethanol-water mixed solution, so that the ethanol therein and the ozone introduced in the subsequent steps can be used to improve the bleaching effect.

[0010] In some embodiments, in step S5, the ozone concentration of the ozone treatment is 60-120 mg / L, and the ozone treatment time is 3-5 minutes.

[0011] In this embodiment, by controlling the concentration and time of ozone treatment, a sufficient amount of ozone can be rapidly penetrated into the fiber under the action of ethanol, and the hydroxyl groups in the ethanol are oxidized into hydroxyl radicals, thereby improving the bleaching effect.

[0012] In some embodiments, in step S1, the concentration of sodium hydroxide in the ethanol-water solution of sodium hydroxide is 10-30 g / L, and the volume ratio of ethanol to water is 9:1-5:5.

[0013] In this embodiment, by controlling the concentration of sodium hydroxide and the volume ratio of ethanol to water, the appropriate amount of ethanol can be used to promote the penetration of sodium hydroxide, and the sodium hydroxide can be used for degreasing treatment of cotton fibers.

[0014] In some embodiments, in step S1, the pick-up rate after padding is 100%-200%. In this embodiment, by controlling the pick-up rate after padding, the cotton fibers can contain an appropriate amount of sodium hydroxide, so that when hydrogen peroxide is added subsequently, it can have a better degreasing and bleaching effect in the presence of sodium hydroxide.

[0015] In some embodiments, in step S2, the concentration of hydrogen peroxide in the ethanol solution of hydrogen peroxide is 5-30 g / L.

[0016] In this embodiment, by controlling the concentration of hydrogen peroxide, an appropriate amount of hydrogen peroxide can be used to effectively degrease and bleach the cotton fibers.

[0017] In some embodiments, in step S2, the pick-up rate after padding is 100%-200%. In this embodiment, the residual ethanol solution of hydrogen peroxide after padding can further play a role in degreasing and bleaching in the steaming process.

[0018] In some embodiments, in step S3, the temperature of the steaming treatment is 95-110℃, and the steaming treatment time is 10-20 min.

[0019] In this embodiment, by controlling the parameters of the steaming treatment, the degreasing and bleaching effect can be improved while the fiber surface is smoother and more uniform to meet the needs of clothing.

[0020] In some embodiments, in step S5, the washing includes water washing, and the water washing time is 1-3 min; the drying temperature is 70-90℃.

[0021] In this embodiment, by washing and drying the cotton fibers, other residual substances in the fibers can be removed to improve their safety.

[0022] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. DETAILED DESCRIPTION

[0023] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application are intended to cover non-exclusive inclusions.

[0025] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0026] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] The traditional cotton fiber degreasing and bleaching process usually requires the use of a large amount of chemicals, mainly including salt, alkali and other chemical additives, to achieve better degreasing and bleaching effects. However, the large amount of chemicals used not only consumes a large amount of water resources for washing, but also the washing wastewater generated after washing is discharged into the natural environment, causing significant environmental pollution.

[0028] In order to solve the technical problem of excessive types and dosages of chemical agents in the degreasing and bleaching process, the present application provides a method for degreasing and bleaching cotton fibers. By successively introducing ethanol and ozone during the degreasing and bleaching process, the bleaching effect is improved while effectively reducing the use of salt, alkali and chemical additives, and reducing the consumption of water resources.

[0029] Specifically, the present invention provides a method for degreasing and bleaching cotton fibers, comprising the following steps: S1. The cotton fiber is placed in an ethanol-water solution of sodium hydroxide and padded to obtain a first cotton fiber; S2. The ethanol solution of hydrogen peroxide is evenly sprayed on the first cotton fiber, and the second cotton fiber is obtained after rolling; S3 steaming the second cotton fiber to obtain a third cotton fiber; S4. The third cotton fiber is placed in an ethanol-water mixed solution for washing, and the fourth cotton fiber is obtained after rolling; S5. The fourth cotton fiber is subjected to ozone treatment, and after washing and drying, degreased and bleached cotton fiber is obtained.

[0030] In the present application, by first placing the cotton fiber in an ethanol-water solution of sodium hydroxide for padding, the ethanol therein can be used to promote the wetting of the cotton fiber and the penetration of sodium hydroxide, so that the surface and interior of the first cotton fiber obtained after padding are loaded with a large amount of sodium hydroxide to improve its degreasing effect. Thereafter, spraying the ethanol solution of hydrogen peroxide can further promote the penetration of hydrogen peroxide in the cotton fiber and improve the stability of hydrogen peroxide, and hydrogen peroxide can synergistically act with sodium hydroxide to improve the degreasing and bleaching effect. Specifically, on the one hand, hydrogen peroxide can react to generate H0O in the alkaline environment provided by sodium hydroxide. ﹣ , achieving a good bleaching effect; on the other hand, hydrogen peroxide can also generate free radicals in an alkaline environment, further improving the degreasing and bleaching effect. Subsequent steaming allows the residual sodium hydroxide and hydrogen peroxide in the cotton fibers to continue to fully react, improving the degreasing and bleaching effect while also making the cotton fiber surface smoother and flatter. At the same time, since a large amount of ethanol evaporates after steaming, the present invention introduces ethanol during the water washing process after steaming, allowing the cotton fibers to fully absorb ethanol in the ethanol-water solution. Subsequently, ozone treatment is performed, allowing the ethanol and ozone to act synergistically. Not only can ethanol promote faster ozone entry into the fiber, but ozone can also oxidize the hydroxyl groups in the ethanol into hydroxyl free radicals, specifically oxidizing pigments. This enhances the bleaching effect while effectively reducing damage to the fiber itself. Furthermore, the hydrophilic groups, such as carboxyl groups, generated by ethanol oxidation can reduce the polarity of the fiber surface, improving the fiber's hydrophilicity.

[0031] By the above-mentioned method, only a small amount of sodium hydroxide, hydrogen peroxide, ethanol and ozone need to be used in the degreasing bleaching of cotton fibers provided by the present application, wherein the hydrogen peroxide and ozone can decompose on their own and will not cause pollution, while ethanol is harmless to the environment, and the removal of sodium hydroxide only requires washing with a small amount of water and / or acid, which significantly reduces the consumption of water resources compared to the harmful chemicals used in large quantities in the traditional treatment process, and is more environmentally friendly. In addition, the method provided by the present application can achieve a good degreasing bleaching effect while omitting chemicals and improving environmental protection effects, and the overall treatment process method is simple, time-consuming, and the degreasing bleaching efficiency is high. It should be noted that the cotton fiber in the present application can be fibrous cotton or a fabric containing the fibrous cotton, and the method for degreasing and bleaching cotton fibers adopted by the present application has a wide range of applications.

[0032] Furthermore, in some embodiments, in step S1, the concentration of sodium hydroxide in the ethanol-water solution is 10-30 g / L, the volume ratio of ethanol to water is 9:1-5:5, and the liquid rate after padding is 100%-200%.

[0033] In the present application, by regulating the concentration of sodium hydroxide and the volume ratio of ethanol to water, an appropriate amount of ethanol can be used to promote the penetration of sodium hydroxide, and the cotton fibers can be degreased using sodium hydroxide; on this basis, by regulating the liquid carrying rate after padding, an appropriate amount of sodium hydroxide can be contained in the cotton fibers so as to synergize with the subsequently added hydrogen peroxide to achieve a better degreasing and bleaching effect.

[0034] Furthermore, in some embodiments, in step S2, the concentration of hydrogen peroxide in the ethanol solution of hydrogen peroxide is 5-30 g / L; and the liquid rate after rolling is 100%-200%.

[0035] In the present application, by regulating the concentration of hydrogen peroxide, an appropriate amount of hydrogen peroxide can be used in synergistic effect with sodium hydroxide to effectively degrease and bleach cotton fibers; and the sodium hydroxide and hydrogen peroxide remaining after rolling can further play a degreasing and bleaching role in the subsequent steaming treatment.

[0036] Furthermore, in some embodiments, in step S3, the temperature of the steaming treatment is 95-110° C., and the time of the steaming treatment is 10-20 minutes.

[0037] In the present application, by regulating the parameters of the steaming treatment, the degreasing and bleaching effect can be improved while making the fiber surface smoother and flatter to meet the wearing requirements.

[0038] Furthermore, in some embodiments, in step S4, the volume ratio of ethanol to water in the ethanol-water mixed solution is 9:1 to 5:5; and the liquid rate after rolling is 100% to 200%.

[0039] In the present application, by using an ethanol-water mixed solution to wash cotton fibers, and regulating the proportion of ethanol and the liquid rate after rolling, the washed cotton fibers can be evenly loaded with an appropriate amount of ethanol, so that it can synergize with the ozone introduced in the subsequent steps to improve the degreasing and bleaching effect.

[0040] Furthermore, in some embodiments, in step S5, the ozone concentration of the ozone treatment is 60-120 mg / L, and the ozone treatment time is 3-5 minutes.

[0041] In the present application, by controlling the concentration and time of ozone treatment, a sufficient amount of ozone can be quickly penetrated into the fiber under the action of ethanol, and the hydroxyl groups in the ethanol are oxidized into hydroxyl free radicals to improve the bleaching effect.

[0042] In some embodiments, in step S5, the washing includes water washing, and the water washing time is 1 to 3 minutes; the drying temperature is 70 to 90° C.; more preferably, the washing may also include acid washing to remove residual sodium hydroxide.

[0043] In the present application, by washing and drying the cotton fibers, other substances remaining in the fibers can be removed, thereby improving their safety in use.

[0044] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0045] Example 1 This embodiment provides a method for degreasing and bleaching cotton fibers, comprising the following steps: S1. The cotton fiber was placed in an ethanol-water solution of sodium hydroxide and padded to obtain a first cotton fiber; wherein the concentration of sodium hydroxide in the ethanol-water solution was 20 g / L, the volume ratio of ethanol to water was 9: 1, and the liquid rate was maintained at 150% after padding; S2. The ethanol solution of hydrogen peroxide was evenly sprayed on the first cotton fiber, and the second cotton fiber was obtained after rolling by a padder; wherein the concentration of hydrogen peroxide in the ethanol solution of hydrogen peroxide was 10 g / L, and the liquid rate was maintained at 200% after rolling; S3. The second cotton fiber was placed in a steamer at 100°C for 15 min to obtain a third cotton fiber; S4. The third cotton fiber was placed in an ethanol-water mixed solution for washing, and the fourth cotton fiber was obtained after rolling by a padder; wherein the volume ratio of ethanol to water in the ethanol-water mixed solution was 9:1, and the liquid rate was maintained at 150% after rolling; S5. The fourth cotton fiber is placed in an ozone chamber for ozone treatment. The ozone concentration in the ozone chamber is 80 mg / L and the treatment time is 3 minutes. The ozone-treated cotton fiber is then washed with water for 2 minutes and dried in an oven at 80°C to obtain degreased and bleached cotton fiber.

[0046] To verify the degreasing and bleaching effect of the cotton fiber in the present embodiment, the whiteness, water absorption time and tensile strength of the cotton fiber were detected and compared with the cotton fiber used in step S1 without any treatment, and the results are shown in Table 1.

[0047] Table 1 Performance parameters of cotton fiber before and after treatment by the method provided in Example 1 As can be seen from Table 1, the bleaching effect of alkali and hydrogen peroxide and the synergistic effect of ethanol and ozone oxidation can effectively destroy pigments and significantly improve whiteness; at the same time, alkali treatment can effectively remove cotton wax, expose hydroxyl groups and enhance hydrophilicity, and the water absorption time is significantly shortened, which can realize instantaneous water absorption; although hydrogen peroxide and ozone oxidation cause cellulose chain rupture, the strength loss is small, which is within an acceptable range.

[0048] Examples 2-5 and Comparative Examples 1-3 Examples 2-5 and Comparative Examples 1-3 each provide a method for degreasing and bleaching cotton fiber, which differs from Example 1 only in that the concentration of sodium hydroxide in the ethanol-water solution of sodium hydroxide and the volume ratio of ethanol to water in step S1 are changed, and the remaining steps are consistent with Example 1, which will not be repeated here. The corresponding parameters in each example and comparative example and the performance parameters of the degreasing and bleached cotton fiber and its comparison with Example 1 are shown in Table 2.

[0049] Table 2 Related parameters in Examples 1-5 and Comparative Examples 1-3 As can be seen from Table 2, higher NaOH concentration (such as 30 g / L) and higher ethanol ratio (such as 9:1) can improve whiteness and hydrophilicity, but may sacrifice strength; on the contrary, low concentration or low ethanol ratio will weaken the dewaxing effect, resulting in a decrease in whiteness and hydrophilicity (such as whiteness 80 and water absorption time 6.1 s in Comparative Example 3), but the strength is well preserved. However, beyond the range, lower NaOH concentration leads to failure of functional modification (such as whiteness 75 and water absorption time 8 s in Comparative Example 1), and higher NaOH concentration causes irreversible damage (such as strength 12.14 N in Comparative Example 2). In the present application, the solubility of ethanol to cotton wax is the key to determining the degreasing effect, and the NaOH concentration needs to be matched with the fiber tolerance threshold. Based on this, the concentration of sodium hydroxide is preferably 10-30 g / L, and the volume ratio of ethanol to water is preferably 9:1-5:5, so as to effectively improve the whiteness and hydrophilicity of the cotton fiber while minimizing the impact on the strength.

[0050] Examples 6-7 and Comparative Examples 4-5 Examples 6-7 and Comparative Examples 4-5 each provide a method for degreasing and bleaching cotton fibers. The only difference from Example 1 is that the concentration of hydrogen peroxide in the ethanol solution of hydrogen peroxide in step S2 is changed. The remaining steps are consistent with Example 1 and are not further described here. Table 3 shows the corresponding parameters in each example and comparative example, as well as the performance parameters of the degreasing and bleaching cotton fibers obtained, and a comparison with Example 1.

[0051] Table 3 Related parameters in Example 1, Examples 6-7 and Comparative Examples 4-5 Table 3 shows that, within a certain range, hydrogen peroxide concentration is positively correlated with bleaching effectiveness. Higher hydrogen peroxide concentrations generate more reactive oxygen radicals, which can degrade more pigments, thereby improving whiteness. However, excessively high hydrogen peroxide concentrations can trigger oxidative breakage of cellulose chains (especially in amorphous regions), resulting in a decrease in strength (e.g., the tensile strength of 10.58 N in Comparative Example 5). Therefore, controlling the hydrogen peroxide concentration is necessary to avoid performance imbalances caused by extreme values. Furthermore, excessive hydrogen peroxide concentrations can trigger excessive oxidation reactions, making the fiber structure loose and porous, shortening water absorption time beyond the normal range, and ultimately reducing whiteness due to fiber degradation or residual oxidation products (e.g., the whiteness of 90% in Comparative Example 5).

[0052] Examples 8-11 and Comparative Examples 6-7 Examples 8-11 and Comparative Examples 6-7 each provide a method for degreasing and bleaching cotton fibers. The only differences from Example 1 are changes in the volume ratio of ethanol to water in the ethanol-water mixed solution in step S4 and the liquid pick-up rate after rolling. The remaining steps are consistent with Example 1 and are not further described here. Table 4 shows the corresponding parameters in each example and comparative example, as well as the performance parameters of the resulting degreasing and bleaching cotton fibers and their comparison with those of Example 1.

[0053] Table 4 Related parameters in Example 1, Examples 8-11 and Comparative Examples 6-7 Table 4 shows that the volume ratio of ethanol to water in the ethanol-water mixture and the post-rolling liquid pick-up rate significantly influence these parameters. Lowering the ethanol ratio reduces ethanol's solubility, leading to decreased whiteness, prolonged water absorption time, and reduced strength due to residual impurities (as seen in Comparative Example 6). A moderate pick-up rate balances washing and subsequent processing, while a low pick-up rate reduces the efficiency of ozone contact with the fabric, resulting in incomplete impurity removal and negatively impacting whiteness and water absorption (as seen in Comparative Example 7).

[0054] Examples 12-14 and Comparative Examples 8-9 Examples 12-14 and Comparative Examples 8-9 each provide a method for degreasing and bleaching cotton fibers. The only difference from Example 1 is the change in the ozone concentration and treatment time in step S5. The remaining steps are consistent with Example 1 and are not further described here. Table 5 shows the corresponding parameters in each example and comparative example, as well as the performance parameters of the degreasing and bleaching cotton fibers obtained, and a comparison with Example 1.

[0055] Table 5 Related parameters in Example 1, Examples 12-14 and Comparative Examples 8-9 As can be seen in Table 5, as the ozone treatment concentration and duration increase, the amount of active oxygen increases, degrading residual pigments and improving whiteness. However, excessive ozone oxidation will also cause cellulose molecular chains to break, reducing strength, and its residual oxidation products will also affect whiteness and water absorption time (as shown in Comparative Example 9). Because hydrophilicity is primarily determined by the degreasing effect in step S1, ozone has a smaller impact, so the water absorption time fluctuates slightly. However, the lack of ozone oxidation will result in the inability to remove residual pigments (especially conjugated structures that are difficult to degrade with hydrogen peroxide), resulting in incomplete bleaching. Although strength is retained, the whiteness / hydrophilicity does not meet the requirements (as shown in Comparative Example 8). Therefore, the ozone concentration must be strictly controlled. Too low a concentration will lead to functional failure, while too high a concentration will cause structural collapse.

[0056] Comparative Example 10 This comparative example provides a method for degreasing and bleaching cotton fibers. The only difference from Example 1 is that the hydrogen peroxide ethanol solution is applied in step S2 in a padding process instead of spraying. The remaining steps are consistent with those in Example 1 and are not described in detail here. The performance parameters of the degreasing and bleaching cotton fibers obtained in this comparative example, and a comparison thereof with those in Example 1, are shown in Table 6.

[0057] Table 6 Performance parameters of Example 1 and Comparative Example 10 As shown in Table 6, when the loading method is changed from spraying to padding, padding causes uneven distribution of hydrogen peroxide, resulting in incomplete local bleaching during steaming and an increase in residual pigment. Extrusion, on the other hand, causes some H2O2 to decompose prematurely, reducing the total amount of effective bleach and decreasing whiteness. Uneven bleaching results in discontinuous coverage of hydrophilic groups on the fiber surface, reducing wetting rate and prolonging water absorption time. Furthermore, extrusion exacerbates fiber deformation, and locally high concentrations of hydrogen peroxide cause excessive oxidative degradation of cellulose during steaming, reducing fiber strength. In this application, a spraying process is used to achieve uniform hydrogen peroxide loading through atomized dispersion, effectively ensuring bleaching consistency and fiber integrity.

[0058] Comparative Example 11 This comparative example provides a method for degreasing and bleaching cotton fibers. Compared to Example 1, the only difference is that the ethanol-water mixed solution in step S4 is replaced with acetonitrile-water. The volume ratio of acetonitrile to water is the same as the volume ratio of ethanol to water in step S4 of Example 1. The remaining steps are consistent with Example 1 and are not further described here. The performance parameters of the degreased and bleached cotton fibers obtained in this comparative example and their comparison with those in Example 1 are shown in Table 7.

[0059] Table 7 Performance parameters of Example 1 and Comparative Example 11 Table 7 shows that when the ethanol-water mixture in S4 was replaced with acetonitrile-water, the overall fiber performance declined. This is because, while acetonitrile can promote ozone physical penetration and improve bleaching uniformity, it cannot generate hydroxyl radicals (·OH), resulting in incomplete oxidation of residual pigments (especially dark conjugated structures), leading to a decrease in whiteness. Furthermore, the use of acetonitrile results in the loss of hydrophilic groups such as carboxyl groups (-COOH) generated by ethanol oxidation, reducing the polarity of the fiber surface. The residual acetonitrile forms a hydrophobic film, further prolonging the water absorption time. Furthermore, ozone is locally enriched in the acetonitrile system, and without the synergistic, mild oxidation of ·OH, ozone directly reacts with the main chain, exacerbating oxidative damage to cellulose and reducing fiber strength. This demonstrates that the use of ethanol in this application is not simply to promote ozone physical penetration. By combining ethanol with ozone, the ethanol is oxidized to generate ·OH, enhancing the bleaching effect, while also increasing the fiber's hydrophilicity and generating ·OH-directed oxidized pigments, while also reducing bulk fiber damage.

[0060] Comparative Example 12 This comparative example provides a method for degreasing and bleaching cotton fibers. The only differences from Example 1 are that the chemical additive sodium dodecyl sulfate (SDS) is introduced into the padding solution used in step S1 at a concentration of 2 g / L. The ethanol-water mixture in step S4 is replaced with water. The remaining steps are identical to those in Example 1 and are not further described here. The performance parameters of the degreasing and bleaching cotton fibers produced in this comparative example, along with a comparison with those in Example 1, are shown in Table 8.

[0061] Table 8 Performance parameters of Example 1 and Comparative Example 12 As can be seen in Table 8, the addition of sodium dodecyl sulfate (SDS) only aids in decontamination through its surface activity, but its effectiveness relies on a single additive. Due to the lack of the efficient degreasing effect of ethanol and the strong oxidative effect of ozone, indicators such as whiteness, water absorption time, and tensile strength are significantly lower than those in Example 1, with whiteness reduced to 80 and water absorption time extended to 6 seconds. However, when ethanol and ozone act synergistically, not only can ethanol enhance degreasing through its high permeability and ozone achieve efficient bleaching through its strong oxidative properties, but the interaction between the two can also more thoroughly remove impurities such as grease and pigments from the fiber surface. This improves whiteness and shortens water absorption time while better maintaining fiber strength, resulting in a significantly better overall effect than conventional chemical additives. Based on this, the method provided in this application can effectively improve degreasing and bleaching effects while reducing the use of chemical additives, thus better meeting environmental requirements.

[0062] In summary, the present application provides a method for degreasing and bleaching cotton fibers, which belongs to the technical field of fiber degreasing and bleaching. The present application provides a method for degreasing and bleaching cotton fibers, comprising: placing cotton fibers in an ethanol-water solution of sodium hydroxide for immersion and rolling to obtain first cotton fibers; spraying an ethanol solution of hydrogen peroxide evenly on the first cotton fibers, and obtaining second cotton fibers after rolling; steaming the second cotton fibers to obtain third cotton fibers; placing the third cotton fibers in an ethanol-water mixed solution for washing, and obtaining fourth cotton fibers after rolling; and ozone-treating the fourth cotton fibers, and obtaining degreasing and bleaching cotton fibers after washing and drying. The present application uses ethanol and ozone in synergistic manner, thereby effectively reducing the use of salt, alkali and chemical additives while improving the bleaching effect, and reducing the consumption of water resources.

[0063] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for degreasing and bleaching cotton fibers, characterized in that: The steps include: S1. The cotton fiber is placed in an ethanol-water solution of sodium hydroxide and padded to obtain a first cotton fiber; S2. The ethanol solution of hydrogen peroxide is evenly sprayed on the first cotton fiber, and the second cotton fiber is obtained after rolling; S3 steaming the second cotton fiber to obtain a third cotton fiber; S4. The third cotton fiber is placed in an ethanol-water mixed solution for washing, and the fourth cotton fiber is obtained after rolling; S5. The fourth cotton fiber is subjected to ozone treatment, and after washing and drying, degreased and bleached cotton fiber is obtained.

2. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S4, the volume ratio of ethanol to water in the ethanol-water mixed solution is 9:1 to 5:

5.

3. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S4, the liquid carrying rate after rolling is 100% to 200%.

4. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S5, the ozone concentration of the ozone treatment is 60-120 mg / L, and the ozone treatment time is 3-5 minutes.

5. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S1, in the ethanol-water solution of sodium hydroxide, the concentration of sodium hydroxide is 10-30 g / L, and the volume ratio of ethanol to water is 9:1-5:

5.

6. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S1, the liquid carrying rate after padding is 100% to 200%.

7. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S2, the concentration of hydrogen peroxide in the ethanol solution of hydrogen peroxide is 5-30 g / L.

8. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S2, the liquid carrying rate after rolling is 100% to 200%.

9. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S3, the steaming temperature is 95-110° C., and the steaming time is 10-20 minutes.

10. The method for degreasing and bleaching cotton fibers according to claim 1, wherein: In step S5, the washing includes water washing, and the water washing time is 1-3 minutes; the drying temperature is 70-90°C.

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