Method for scouring and bleaching cotton fibers with high whiteness

Abstract

The present invention provides a method for scouring and bleaching cotton fibers with high whiteness. The method comprises the following steps: mixing a prepared alkali solution and a hydrogen peroxide-ethanol solution; adding an auxiliary agent PPC, stirring the mixture to prepare a scouring and bleaching solution; then placing the cotton fibers in a special scouring and bleaching solution for high temperature scouring and bleaching, and finally washing the fibers to obtain cotton fibers with a whiteness increased to 94.17%. The hydrophilic group in PPC can rapidly dissolve the oil on the surface of the cotton fibers and has a strong emulsifying and washing effect, so that hydrogen peroxide and alkali can rapidly enter the fiber surface. At the same time, PPC, as an activator of hydrogen peroxide, can reduce the reaction temperature and can react with H in hydrogen peroxide. + The reaction occurs, effectively releasing more free radicals, thereby accelerating the bleaching reaction; and because the surface tension of ethanol is much smaller than that of water, the wetting properties of the ethanol-water system are further enhanced under high temperature conditions, making it easier for ethanol to enter the cotton fiber and cause it to swell quickly.

Description

Technical Field

[0001] The invention relates to the technical field of high-temperature scouring and bleaching of non-woven fabrics, in particular to a scouring and bleaching method for high-whiteness cotton fibers. Background Art

[0002] Cotton fibers contain impurities such as pectin, cotton seed husks, grease, wax, nitrogen-containing substances, and pigments. During the scouring and bleaching process, they undergo saponification, emulsification, and oxidation reactions under the action of sodium hydroxide and oxidants to generate soluble salts, which eventually remove the impurities by washing. In the traditional scouring and bleaching process, it is necessary to add hydrogen peroxide, sodium hydroxide, scouring agents, stabilizers and other chemical substances to the aqueous solution, put the cotton into the aqueous solution and heat it at high temperature for a period of time to ensure the stability and thoroughness of the scouring and bleaching. However, the traditional scouring and bleaching process requires the use of a large amount of chemical additives, and the waste liquid after scouring and bleaching will cause certain pollution to the environment, and the whiteness of the resulting fabric is not very high.

[0003] Therefore, it is of great significance to study a scouring and bleaching method for fabrics with low de-bleaching cost and high whiteness in the field of high-temperature scouring and bleaching of non-woven fabrics.

[0004] In view of this, it is necessary to design a cotton fiber scouring and bleaching method with high whiteness to solve the above problems. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the object of the present invention is to provide a method for scouring and bleaching cotton fibers with high whiteness, which is used to achieve efficient scouring and bleaching of cotton fibers while using a small amount of auxiliary agents.

[0006] To achieve the above object, the present invention provides a method for scouring and bleaching cotton fibers with high whiteness, comprising the following steps:

[0007] S1, prepare a bleaching liquid: first dissolve liquid alkali in water to prepare an alkali solution, dissolve hydrogen peroxide in anhydrous ethanol to prepare a hydrogen peroxide-ethanol solution; then mix the alkali solution and the hydrogen peroxide-ethanol solution, add an auxiliary agent PPC, stir evenly and prepare a bleaching liquid;

[0008] S2, high temperature scouring and bleaching: immersing the cotton fiber in the scouring and bleaching solution described in step S1 according to a predetermined bath ratio, and soaking at a predetermined temperature for a predetermined time;

[0009] S3, washing: the cotton fibers after high-temperature boiling and bleaching in step S2 are subjected to soap washing, hot water washing, cold water washing and drying treatment to obtain a finished product.

[0010] Furthermore, the PPC in step S1 includes 15-20% fatty alcohol polyether 6-15EO, 5-10% diethylene glycol monobutyl ether, 10-20% branched and linear C13-15 alcohol ethoxylates, 1-5% monohydrated citric acid, 0.0015-0.01% isothiazolinone, and 0.1-1% isotridecanol.

[0011] Furthermore, in the bleaching liquid in step S1, the volume ratio of the anhydrous ethanol to the water is 50:50-70:30, the concentration of the alkali is 10-12 g / L, the concentration of the hydrogen peroxide is 9-12 g / L, and the concentration of the auxiliary agent PPC is 1.5-2 g / L.

[0012] Furthermore, in step S2, the predetermined bath ratio of the cotton fiber to the bleaching liquid is 1 g: 20-30 L.

[0013] Furthermore, the cotton fiber in step S2 includes one of cotton non-woven fabric or cotton fabric.

[0014] Furthermore, in step S2, the predetermined temperature is 80-90° C., and the predetermined soaking time is 60-90 min.

[0015] Furthermore, the soaping liquid used in the soaping operation in step S3 includes soap flakes, sodium salt and water.

[0016] Furthermore, in the soaping liquid, the concentration of the soap flakes is 1 to 5 g / L; and the concentration of the sodium salt is 1 to 3 g / L.

[0017] Furthermore, in step S3, the temperature of the soap washing and the temperature of the hot water washing are 90-100°C.

[0018] Furthermore, in step S3, the soaping bath ratio of the cotton fiber to the soaping liquid is 1 g:10-50 L.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention provides a method for scouring and bleaching cotton fibers with high whiteness, which comprises dissolving liquid alkali in water to prepare an alkaline solution, dissolving hydrogen peroxide in anhydrous ethanol to prepare a hydrogen peroxide-ethanol solution; then mixing the alkaline solution and the hydrogen peroxide-ethanol solution; then adding the auxiliary agent PPC, stirring evenly to prepare a scouring and bleaching liquid; then placing the cotton fibers in a special scouring and bleaching liquid for high-temperature scouring and bleaching, and finally washing to obtain the finished product. The special scouring and bleaching liquid can increase the whiteness of the scouring and bleaching cotton fibers to 94.17% by adding a small amount of the auxiliary agent PPC under the premise of using ethanol as a stabilizer for hydrogen peroxide in an alkaline environment. This is because the hydrophilic group in PPC can quickly dissolve the oil on the surface of the cotton fibers and has a strong emulsifying and washing effect, so that hydrogen peroxide and alkali can quickly enter the fiber surface. At the same time, PPC, as an activator of hydrogen peroxide, can reduce the reaction temperature and can react with H in hydrogen peroxide. + The reaction occurs, effectively releasing more free radicals, thereby accelerating the bleaching reaction.

[0021] 2. A method for scouring and bleaching cotton fibers with high whiteness provided by the present invention is to add ethanol to the prepared scouring and bleaching liquid. Since the surface tension of ethanol is much smaller than that of water, and high temperature also reduces the surface tension of water and ethanol, the wetting property of the ethanol-water system is further enhanced. Therefore, the strong wetting property and strong penetration of water vapor and ethanol can make ethanol more easily enter the interior of the cotton fibers to make them swell quickly. Moreover, ethanol molecules are larger than water molecules, which can make the volume of cotton fibers swell more, thereby increasing the contact area between cotton fibers and sodium hydroxide, which is beneficial to reducing the reaction time. In addition, ethanol can also be directly used as a stabilizer for hydrogen peroxide, and the cotton fibers scour and bleach can obtain a more ideal whiteness. BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below in conjunction with specific embodiments.

[0023] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0024] A method for scouring and bleaching cotton fibers with high whiteness comprises the following steps:

[0025] S1. Prepare a bleaching liquid: first dissolve liquid alkali in water to prepare an alkali solution, dissolve hydrogen peroxide in anhydrous ethanol to prepare a hydrogen peroxide-ethanol solution; then mix the alkali solution and the hydrogen peroxide-ethanol solution, add an auxiliary agent PPC, stir evenly and prepare a bleaching liquid; wherein the auxiliary agent PPC comprises fatty alcohol polyether 6-15EO at a concentration of 15-20%, diethylene glycol monobutyl ether at a concentration of 5-10%, and branched and straight-chain C13-15 alcohol ethoxylates (including branched and straight-chain C13-15 alcohol ethoxylates at a concentration of 5-10%). 15 alcohol ethoxylate (7EO) and 5-10% branched and straight-chain C13-15 alcohol ethoxylate (5EO)), 1-5% monohydrate citric acid, 0.0015-0.01% isothiazolinone, 0.1-1% isotridecanol, and the specific ingredients are shown in Table 1; in the prepared bleaching liquid, the volume ratio of the anhydrous ethanol to the water is 50:50-70:30, the concentration of the alkali is 10-12g / L, the concentration of the hydrogen peroxide is 9-12g / L, and the concentration of the auxiliary agent PPC is 1.5-2g / L;

[0026] S2, high temperature scouring and bleaching: immerse the cotton fiber in the scouring and bleaching solution described in step S1 at a bath ratio of 1g:20-30L, and soak at a temperature of 80-90°C for 60-90min;

[0027] S3, washing: the cotton fiber after high-temperature boiling and bleaching in step S2 is subjected to soap washing, hot water washing, cold water washing and drying to obtain a finished product; the soap washing process is: firstly, soap flakes, sodium salt and water are mixed to prepare a soap washing solution with a soap flake concentration of 1 to 5 g / L and a sodium salt concentration of 1 to 3 g / L, and then the cotton fiber is placed in the soap washing solution at a bath ratio of 1 g:10 to 50 L, and soap washing is carried out at a temperature of 90 to 100° C.; the temperature of the hot water washing is 90 to 100° C.

[0028] In this way, the specially prepared bleaching liquid can increase the whiteness of the bleached cotton fiber to 94.17% by adding a small amount of auxiliary agent PPC in an alkaline environment and using ethanol as a stabilizer for hydrogen peroxide. This also saves the cost of debleaching to a certain extent, which is conducive to the promotion of green environmental protection.

[0029] Specifically, in some embodiments of the present invention, the volume ratio of the ethanol-water system in step S1 is 50:50 to 70:30.

[0030] In this way, the ethanol-water system replaces the pure water system. According to the wetting principle, the surface tension of ethanol is much smaller than that of water. At the same time, high temperature also reduces the surface tension of water and ethanol, further enhancing the wetting performance of the ethanol-water system. Therefore, the strong wetting performance and strong penetration of water vapor and ethanol can make ethanol more easily enter the cotton fiber and make it swell quickly; and the ethanol molecule is larger than the water molecule, which can make the volume of the cotton fiber swell larger, thereby increasing the area of ​​contact between the cotton fiber and the sodium hydroxide, which is conducive to reducing the time for the reaction. In addition, ethanol can also be directly used as a stabilizer for hydrogen peroxide to reduce the amount of stabilizer used.

[0031] Specifically, in some embodiments of the present invention, the cotton fiber in step S2 includes one of cotton non-woven fabric or cotton fabric.

[0032] The working method of a high-whiteness cotton fiber scouring and bleaching method provided by the present invention is described below:

[0033] Example 1

[0034] This embodiment provides a method for scouring and bleaching cotton fibers with high whiteness, comprising the following steps:

[0035] S1. Prepare a bleaching liquid: weigh 1.2g of caustic soda and dissolve it in 30ml of water, stir it evenly to obtain a caustic soda solution; weigh 1.1g of hydrogen peroxide and dissolve it in 70ml of anhydrous ethanol, stir it evenly to obtain a hydrogen peroxide-ethanol solution; then mix the caustic soda solution and the hydrogen peroxide-ethanol solution; then add an auxiliary agent PPC, stir it evenly to prepare a bleaching liquid; wherein the PPC includes a fatty alcohol polyether 6-15E at a concentration of 15% O, 10% diethylene glycol monobutyl ether, 8% branched and linear C13-15 alcohol ethoxylate (7EO), 8% branched and linear C13-15 alcohol ethoxylate (5EO), 1% citric acid monohydrate, 0.002% 2-methyl-3(2H)-isothiazolinone, 0.5% isotridecanol; the concentration of PPC in the bleaching liquid is 1.5 g / L;

[0036] S2, high temperature scouring and bleaching: immerse the cotton fiber in the scouring and bleaching solution described in step S1 at a bath ratio of 1g:20L, and soak in an oven at 90°C for 60min;

[0037] S3, washing: 5g / L soap flakes and 2g / L sodium carbonate aqueous solution are uniformly mixed to obtain a soaping solution. Subsequently, the cotton fabric after scalding and bleaching in step S2 is soaped at 95°C, washed with hot water at 95°C, washed with cold water, and then dried to obtain a finished product.

[0038] Embodiments 2 to 6

[0039] Embodiments 2 to 6 respectively provide a method for scouring and bleaching cotton fibers with high whiteness, which differ from Embodiment 1 in that:

[0040] In step S1 of Example 2, the concentration of PPC in the prepared bleaching liquid is 2 g / L.

[0041] In step S1 of Example 3, the prepared bleaching liquid contains 40 ml of water and 60 ml of anhydrous ethanol.

[0042] In step S1 of Example 4, the prepared bleaching liquid contains 50 ml of water and 50 ml of anhydrous ethanol.

[0043] In step S1 of Example 5, 1 g of caustic soda was weighed into the prepared bleaching liquid.

[0044] In step S1 of Example 6, 0.9 g of hydrogen peroxide was weighed into the prepared bleaching liquid.

[0045] The remaining steps are consistent with those in Example 1 and will not be repeated here.

[0046] Comparative Examples 1 to 15

[0047] Comparative Examples 1 to 15 respectively provide a method for scouring and bleaching cotton fibers with high whiteness, and compared with Example 1, the difference is that:

[0048] In step S1 of comparative example 1, the concentration of PPC in the prepared bleaching liquid is 1 g / L.

[0049] In step S1 of comparative example 2, the concentration of PPC in the prepared bleaching liquid is 2.5 g / L.

[0050] In step S1 of comparative example 3, the prepared bleaching liquid contains 60 ml of water and 40 ml of anhydrous ethanol.

[0051] In step S1 of comparative example 4, the prepared bleaching liquid contains 70 ml of water and 30 ml of anhydrous ethanol.

[0052] In step S1 of comparative example 5, the prepared bleaching liquid contains 100 ml of water and 0 ml of anhydrous ethanol.

[0053] In step S1 of comparative example 6, the prepared bleaching liquid contains 20 ml of water and 80 ml of anhydrous ethanol.

[0054] In step S1 of comparative example 7, 0.8 g of caustic soda was weighed into the prepared bleaching liquid.

[0055] In step S1 of comparative example 8, 1.5 g of caustic soda was weighed into the prepared bleaching liquid.

[0056] In step S1 of comparative example 9, 0.6 g of hydrogen peroxide was weighed into the prepared bleaching liquid.

[0057] In step S1 of comparative example 10, 1.4 g of hydrogen peroxide was weighed into the prepared bleaching liquid.

[0058] In step S1 of comparative example 11, no auxiliary agent PPC is added to the prepared bleaching liquid.

[0059] In step S1 of comparative example 12, no hydrogen peroxide is added to the prepared bleaching liquid.

[0060] In step S1 of comparative example 13, the auxiliary agent added to the prepared bleaching liquid is fatty alcohol poly(ethylene glycol) 6-15EO.

[0061] In step S1 of comparative example 14, the auxiliary agent added to the prepared bleaching liquid is citric acid monohydrate.

[0062] In step S1 of comparative example 15, the auxiliary agent added to the prepared bleaching liquid is fatty alcohol polyoxyethylene ether.

[0063] The remaining steps are consistent with those in Example 1 and will not be repeated here.

[0064] The specific parameters and experimental results are shown in Table 2.

[0065] Table 1 Composition of additive PPC

[0066]

[0067]

[0068] Table 2 Specific parameters and experimental results in the embodiments and comparative examples

[0069]

[0070] It can be seen from the experimental results in Table 2 that, by comparing Examples 1 to 2 and Comparative Examples 1 to 2, it is found that when the concentration of the auxiliary agent PPC in the bleaching liquid increases from 1 g / L to 2 g / L, the whiteness of the cotton fiber after high-temperature bleaching increases from 93.25% to 94.17%; and the corresponding water absorption time of the cotton fiber decreases from 2.94 s to 2.69 s, and when the concentration of the auxiliary agent PPC in the bleaching liquid continues to increase to 2.5 g / L, the whiteness of the cotton fiber after high-temperature bleaching no longer increases, because its emulsification and penetration effect has reached saturation, and it can no longer synergize with hydrogen peroxide to improve the whiteness. By comparing Example 1, Examples 3-4 and Comparative Examples 3-6, it can be seen that in the bleaching liquid, as the content of anhydrous ethanol continues to increase, the whiteness of the cotton fiber after high-temperature bleaching increases, and the corresponding water absorption time of the cotton fiber also decreases; and when the content of anhydrous ethanol continues to increase to a volume ratio of anhydrous ethanol to water of 80:20, the whiteness of the cotton fiber after high-temperature bleaching is 94.15%, and the corresponding water absorption time of the cotton fiber is 2.66s. At this time, the increase in the whiteness of the cotton fiber is no longer significant, and the solubility of the water-soluble substance generated by the reaction of sodium hydroxide and hydrogen peroxide under this ratio, sodium peroxide, in water has reached saturation, and precipitation will precipitate, solid-liquid separation, resulting in uneven solution, which is not conducive to the degreasing and bleaching process during continuous production. In contrast to Example 1 and Comparative Example 5, when ethanol is added to the bleaching liquid to which an appropriate amount of auxiliary agent PPC is added, the whiteness of the cotton fiber after high-temperature bleaching can be further increased from 90.83% to 94.05%, and the corresponding water absorption time is reduced from 2.94s to 2.72s. This is because the ethanol in the bleaching liquid can not only be used as a stabilizer for hydrogen peroxide; but also in the ethanol-water system, according to the wetting principle, the surface tension of ethanol is much smaller than that of water, and the high temperature also reduces the surface tension of water and ethanol, further enhancing the wetting performance of the ethanol-water system, so the strong wetting performance and strong penetration of water vapor and ethanol can make ethanol easier to enter the interior of the cotton fiber to make it swell quickly, and the ethanol molecule is larger than the water molecule, which can make the volume of the cotton fiber swell more, thereby increasing the contact area between the cotton fiber and the sodium hydroxide, which is conducive to reducing the reaction time, so the cotton fiber finally bleached can obtain a more ideal whiteness. By comparing Example 1, Example 5, and Comparative Examples 7-8, it can be seen that when the alkali content in the bleaching liquid increases from 0.8g to 1.2g, the whiteness of the cotton fiber after high-temperature bleaching increases from 92.21% to 94.05%, and when the alkali content continues to increase to 1.5g, the whiteness of the cotton fiber after high-temperature bleaching remains unchanged; and the corresponding water absorption time of the cotton fiber is first reduced from 2.85s to 2.72s and then remains unchanged. This is because as the concentration of alkali increases, its swelling effect on the fiber is stronger. When the alkali is excessive, the fiber swelling reaches saturation, and the whiteness and water absorption time remain unchanged.By comparing Example 1, Example 6, and Comparative Examples 9 to 10, it can be seen that when the content of hydrogen peroxide in the bleaching liquid increases from 0.6g to 1.2g, the whiteness of the cotton fiber after high-temperature bleaching increases from 91.2% to 94.05%, and the corresponding water absorption time of the cotton fiber is reduced from 2.98s to 2.72s; when the content of hydrogen peroxide continues to increase to 1.4g, although the whiteness of the cotton fiber continues to increase to 95.24%, the corresponding water absorption time of the cotton fiber no longer decreases. This is because as the concentration of hydrogen peroxide increases, its oxidizing ability increases, the whiteness increases, but the grease on its surface has been completely removed, so its water absorption time first decreases and then remains unchanged. Comparing Example 1 and Comparative Examples 11 to 15, it can be seen that when the PPC auxiliary agent is not added to the bleaching liquid, the whiteness of the cotton fiber after high-temperature bleaching is only 87.28%; when hydrogen peroxide is not added to the bleaching liquid, the whiteness of the cotton fiber after high-temperature bleaching is only 64.39%; and when the PPC in the special bleaching liquid is replaced with fatty alcohol polyethylene glycol ether 6-15EO or monohydrated citric acid or fatty alcohol polyoxyethylene ether of the same content, the whiteness of the cotton fiber after high-temperature bleaching is only 88.46%. Therefore, only by using the special bleaching liquid provided by the present invention can the whiteness of the cotton fiber after high-temperature bleaching be as high as 94.17%, and the water absorption time is as short as 2.69s. This is because the hydrophilic group in PPC can quickly dissolve the grease on the surface of the cotton fiber and has a strong emulsifying and washing effect, so that hydrogen peroxide and alkali can quickly enter the fiber surface. At the same time, PPC can also be used as an activator of hydrogen peroxide, which can reduce the reaction temperature and can react with H in hydrogen peroxide. + The reaction occurs, effectively releasing more free radicals, thereby accelerating the bleaching reaction. Therefore, under the synergistic effect of different components in this special bleaching liquid, the whiteness of cotton fibers can be further improved.

[0071] In summary, the present invention provides a method for scouring and bleaching cotton fibers with high whiteness, wherein the alkaline solution is prepared by dissolving liquid alkali in water, and the hydrogen peroxide is dissolved in anhydrous ethanol to prepare a hydrogen peroxide-ethanol solution; the alkaline solution and the hydrogen peroxide-ethanol solution are then mixed; the auxiliary agent PPC is then added, and the mixture is stirred evenly to prepare a scouring and bleaching liquid; the cotton fibers are then placed in a special scouring and bleaching liquid for high-temperature scouring and bleaching, and finally washed to obtain the finished product. The special scouring and bleaching liquid can increase the whiteness of the scouring and bleaching cotton fibers to 94.17% by adding a small amount of the auxiliary agent PPC under the premise of using ethanol as a stabilizer for hydrogen peroxide in an alkaline environment. This is because the hydrophilic group in PPC can quickly dissolve the oil on the surface of the cotton fibers and has a strong emulsifying and washing effect, so that hydrogen peroxide and alkali can quickly enter the fiber surface. At the same time, PPC, as an activator for hydrogen peroxide, can reduce the reaction temperature and can react with H in hydrogen peroxide. +Reactions occur, effectively releasing more free radicals, thereby accelerating the bleaching reaction. In addition, the ethanol added in the bleaching liquid, because its surface tension is much smaller than that of water, and high temperature also reduces the surface tension of water and ethanol, further enhancing the wetting properties of the ethanol-water system, so the strong wetting properties and strong penetration of water vapor and ethanol can make ethanol easier to enter the cotton fiber to make it swell quickly; and ethanol molecules are larger than water molecules, which can make the volume of cotton fibers swell more, thereby increasing the area of ​​cotton fibers in contact with sodium hydroxide, which is conducive to reducing the time for the reaction. In addition, ethanol can also be directly used as a stabilizer for hydrogen peroxide, and the cotton fibers finally bleached can obtain a more ideal whiteness.

Claims

1. A method for scouring and bleaching cotton fibers with high whiteness, characterized in that: The following steps are involved: S1, prepare a bleaching liquid: first dissolve liquid alkali in water to prepare an alkali solution, dissolve hydrogen peroxide in anhydrous ethanol to prepare a hydrogen peroxide-ethanol solution; then mix the alkali solution and the hydrogen peroxide-ethanol solution, add an auxiliary agent PPC, stir evenly and prepare a bleaching liquid; The auxiliary agent PPC includes 15-20% fatty alcohol polyether 6-15EO, 5-10% diethylene glycol monobutyl ether, 10-20% branched and straight-chain C13-15 alcohol ethoxylates, 1-5% monohydrated citric acid, 0.0015-0.01% isothiazolinone, and 0.1-1% isotridecanol; In the bleaching liquid, the concentration of the auxiliary agent PPC is 1.5-2 g / L; In the bleaching liquid, the volume ratio of the anhydrous ethanol to the water is 50:50 to 70:30, the concentration of the alkali is 10 to 12 g / L, and the concentration of the hydrogen peroxide is 9 to 12 g / L; S2, high temperature scouring and bleaching: immersing the cotton fiber in the scouring and bleaching solution described in step S1 according to a predetermined bath ratio, and soaking at a predetermined temperature for a predetermined time; S3, washing: the cotton fibers after high-temperature boiling and bleaching in step S2 are subjected to soap washing, hot water washing, cold water washing and drying treatment to obtain a finished product.

2. The method for scouring and bleaching cotton fibers with high whiteness according to claim 1, characterized in that: In step S2, the predetermined bath ratio of the cotton fiber to the bleaching liquid is 1 g: 20 to 30 L.

3. The method for scouring and bleaching cotton fibers with high whiteness according to claim 2, characterized in that: The cotton fibers in step S2 include cotton non-woven fabrics.

4. The method for scouring and bleaching cotton fibers with high whiteness according to claim 3, characterized in that: The predetermined temperature in step S2 is 80-90° C., and the predetermined soaking time is 60-90 minutes.

5. The method for scouring and bleaching cotton fibers with high whiteness according to claim 1, characterized in that: The soaping liquid used in the soaping operation in step S3 includes soap flakes, sodium salt and water.

6. The method for scouring and bleaching cotton fibers with high whiteness according to claim 5, characterized in that: In the soaping liquid, the concentration of the soap flakes is 1 to 5 g / L; the concentration of the sodium salt is 1 to 3 g / L.

7. The method for scouring and bleaching cotton fibers with high whiteness according to claim 1, characterized in that: The temperature of the soap washing and the temperature of the hot water washing in step S3 are 90-100°C.

8. The method for scouring and bleaching cotton fibers with high whiteness according to claim 6, characterized in that: In step S3, the soaping bath ratio of the cotton fiber to the soaping liquid is 1 g: 10 to 50 L.

Images