Cold pad-batch desizing and bleaching method for cotton

Abstract

The present invention provides a cold pad-batch desizing and bleaching method for cotton. First, the cotton product is impregnated and rolled in an alkali-oxygen solution with a preset concentration. The alkali-oxygen solution is an ethanol-water mixed solution composed of hydrogen peroxide, sodium hydroxide, dipotassium hydrogen phosphate, and a mixed auxiliary agent. The mixed auxiliary agent is a mixed aqueous solution of fatty alcohol polyoxyethylene ether 6-15EO, diethylene glycol monobutyl ether, branched and straight-chain C13-15 alcohol ethoxylate 7EO, branched and straight-chain C13-15 alcohol ethoxylate 5EO, citric acid monohydrate, 2-methyl-3(2H)-isothiazolinone, and isotridecanol. Then, the impregnated and rolled cotton product is first wound into a roll, then wrapped with a plastic film and rotated uniformly for stacking. Then, the wound and stacked cotton product is successively subjected to soaping, hot water washing, cold water washing, and drying to obtain the finished product. Through the synergistic effect of various substances in the mixed auxiliary agent and the synergistic effect of various substances in the alkali-oxygen solution, the present invention makes the performance of the finished product obtained by cold pad-batch desizing and bleaching better.

Description

Technical Field

[0001] The present invention relates to the technical field of cold pad-batch debleaching of cotton, and particularly to a method for cold pad-batch debleaching of cotton. Background Art

[0002] As an important part of natural fibers, cotton fibers are widely favored for their unique comfort, breathability, and softness. Due to the presence of coexisting substances in natural cellulose fibers such as pectin substances, cottonseed hulls, oils, waxes, nitrogen-containing substances, and pigments, the degreasing and bleaching (hereinafter referred to as debleaching) of cotton and subsequent processes such as functional finishing and dyeing are greatly affected.

[0003] Traditional debleaching processes mainly include two methods: high-temperature boiling and cold pad-batch debleaching. Among them, high-temperature boiling mainly involves putting textiles into a boiling and bleaching container, adding a certain amount of sodium hydroxide, oxidants, and other scouring agents, stabilizers and other chemical substances, and performing high-temperature boiling treatment; under high-temperature conditions, substances such as oils on cotton fibers will undergo saponification reactions, emulsification reactions, and oxidation reactions to form soluble salts, and then the salts and other impurities are removed by water washing. However, due to its high energy consumption and great damage to fibers, the application of high-temperature boiling is limited. Cold pad-batch debleaching generally involves padding cotton fabrics with an alkaline solution at room temperature, and then successively passing through processes such as high-temperature steam scouring, high-temperature steam bleaching with hydrogen peroxide, and water washing; compared with the high-temperature boiling process, the padding liquor temperature of the cold pad-batch debleaching process is low, the required concentration of the alkaline solution is high, and the penetration of the alkaline solution into cotton is more difficult. Therefore, it is usually necessary to add auxiliaries with functions such as penetration, emulsification, stabilization, and washing, such as scouring agents and penetrants. Traditional cold pad-batch debleaching also has disadvantages such as complex process flow, long time consumption, large consumption of water, electricity, and steam, and large sewage discharge.

[0004] In order to expand the application prospects of cold pad-batch debleaching, the patent with the authorization number CN109736071B discloses a low-temperature cold pad-batch pretreatment process for fabric surface. First, the fabric is put into a microwave plasma reaction chamber for microwave plasma surface activation treatment, and then the fabric is respectively subjected to freeze-drying, padding working solution, coiling and sealing stacking, short steaming and water washing, and drying processes; although this method reduces the concentration of the alkali-oxygen solution and reduces water consumption, this method requires prior surface activation of the fabric using microwaves, etc., which will damage the structure and performance of the fabric to a certain extent, and the whiteness needs to be improved. At the same time, the process is complex, the process flow is long, and the time consumption is large.

[0005] The patent with the application number CN109667132A discloses a cold pad-batch pretreatment method for cotton-type textiles. By changing the cold pad-batch process route of cotton-type textiles and the preparation method of lye and bleaching solution in the cold pad-batch process of cotton-type textiles, the cotton-type textiles are successively impregnated with lye formed by mixing a high proportion of alcohol organic solvents and sodium hydroxide, and bleaching solution formed by mixing a high proportion of alcohol organic solvents and hydrogen peroxide, and then cold pad-batch pretreatment is carried out. This method requires separately preparing lye and bleaching solution, and placing the fabric in two treatment solutions successively for impregnation treatment, with a complex operation process and an increased process flow.

[0006] The patent with the application number CN114875654A discloses a cold pad-batch pretreatment process for cotton fabric with low strength loss in desizing, scouring and bleaching. Based on the cold pad-batch pretreatment process, hydrogen peroxide, sodium hydroxide, potassium peroxymonosulfate compound salt, sodium aminosulfonate and calcium sulfate are used for cold pad-batch pretreatment of cotton fabric, and then alkali washing and short steam heating are carried out to achieve the purpose of efficient impurity removal and bleaching. In this method, the dosages of sodium hydroxide and hydrogen peroxide are relatively large, which will cause damage to the fabric to a certain extent; there are relatively many added salt substances, and the large discharge of washing liquid burdens the water body.

[0007] In view of this, it is necessary to design an improved cold pad-batch debleaching method for cotton to solve the above problems. Summary of the Invention

[0008] The purpose of the present invention is to provide a cold pad-batch debleaching method for cotton. By preparing an alkali-oxygen solution with appropriate proportions of ethanol, water, sodium hydroxide, hydrogen peroxide and a mixed auxiliary agent, and controlling the proportions of various substances in the mixed auxiliary agent to form a special network structure among the mixed auxiliary agents, sodium hydroxide and hydrogen peroxide are firmly attached to the surface and inside of cotton products. Through the synergistic effect of various substances in the mixed auxiliary agent and the synergistic effect of various substances in the alkali-oxygen solution, the performance of the finished product obtained by cold pad-batch debleaching is better.

[0009] To achieve the above invention purpose, the present invention provides a cold pad-batch debleaching method for cotton, including the following steps:

[0010] S1. Impregnation: Placing the cotton product in an alkali-oxygen solution with a preset concentration for impregnation; the alkali-oxygen solution is an ethanol-water mixed solution composed of hydrogen peroxide, sodium hydroxide, dipotassium hydrogen phosphate and a mixed auxiliary agent, and the mixed auxiliary agent is a mixed aqueous solution of fatty alcohol polyoxyethylene 6-15EO, diethylene glycol monobutyl ether, branched and straight-chain C13-15 alcohol ethoxylate 7EO, branched and straight-chain C13-15 alcohol ethoxylate 5EO, citric acid monohydrate, 2-methyl-3(2H)-isothiazolinone and isotridecanol.

[0011] S2. Coiling and stacking: Coiling the cotton product impregnated in step S1 first, and then wrapping it with a plastic film and rotating it evenly for stacking;

[0012] S3. Washing and drying: The cotton products after being coiled and piled in step S2 are successively subjected to soaping, hot water washing, cold water washing and drying to obtain finished products.

[0013] As a further improvement of the present invention, in step S1, the mass concentration of fatty alcohol polyoxyethylene 6 - 15EO in the mixed auxiliary agent is 15% - 20%, the mass concentration of diethylene glycol monobutyl ether is 5% - 10%, the mass concentration of branched and linear C13 - 15 alcohol ethoxylate 7EO is 5% - 10%, the mass concentration of branched and linear C13 - 15 alcohol ethoxylate 5EO is 5% - 10%, the mass concentration of citric acid monohydrate is 1% - 5%, the mass concentration of 2 - methyl - 3(2H) - isothiazolinone is 0.0015% - 0.01%, and the mass concentration of isotridecanol is 0.1% - 1%.

[0014] As a further improvement of the present invention, in step S1, the concentration of hydrogen peroxide in the alkali - oxygen solution is 5 - 15 g / L, the concentration of sodium hydroxide is 8 - 16 g / L, the concentration of dipotassium hydrogen phosphate is 5 - 7 g / L, the concentration of the mixed auxiliary agent is 1 - 2 g / L, and the volume ratio of ethanol to water is 80%:20% - 60%:40%.

[0015] As a further improvement of the present invention, in step S1, padding is carried out by one - dip and one - nip, the liquor pickup is 120% - 200%, and the padding temperature is 20 - 25 °C.

[0016] As a further improvement of the present invention, in step S2, the temperature of the piling is 20 - 25 °C, the time of piling is 12 - 24 h; the rotation speed of the uniform rotation is 5 - 10 r / min.

[0017] As a further improvement of the present invention, step S3 is specifically: The cotton products after being coiled and piled in step S2 are first soaped at 95 °C for 1 time, then washed with water at 95 °C for 1 time, and finally pickled for 1 time.

[0018] As a further improvement of the present invention, the soaping is carried out in a mixed aqueous solution of 5 g / L of soap powder and 2 g / L of sodium bicarbonate.

[0019] As a further improvement of the present invention, first dissolve a preset mass of sodium hydroxide in a preset mass of water; then add it to a preset mass of ethanol, and after stirring evenly; then successively add dipotassium hydrogen phosphate and the mixed auxiliary agent thereto, and mix evenly to obtain the alkali - oxygen solution.

[0020] As a further improvement of the present invention, the cotton products are one of cotton fabrics and cotton non - woven fabrics.

[0021] As a further improvement of the present invention, the whiteness of the obtained finished product is as high as 94.17; the longitudinal strength is as high as 99.0 N; the water absorption time is as low as 1.95 s.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) A cold pad-batch desizing and bleaching method for cotton provided by the present invention prepares an alkali-oxygen solution containing ethanol, water, sodium hydroxide, hydrogen peroxide, dipotassium hydrogen phosphate and a mixed auxiliary agent. During the cold pad-batch desizing and bleaching process of cotton products, first, an appropriate amount of ethanol can reduce the surface tension between the cotton products and the solution, enabling the cotton products to have excellent wettability in the alkali-oxygen solution, so that a large amount of alkali-oxygen solution adheres to the surface of the cotton products; second, ethanol has the characteristic of high permeability, enabling the alkali-oxygen solution to quickly enter the interior of the cotton products. Different degrees of cross-linking and entanglement occur between the long-chain compounds, short-chain compounds and cyclic compounds in the mixed auxiliary agent, and they are bonded to each other through hydrogen bonds to form a special network structure. This network structure can encapsulate sodium hydroxide, hydrogen peroxide and dipotassium hydrogen phosphate, enabling sodium hydroxide, hydrogen peroxide and dipotassium hydrogen phosphate to firmly contact the cotton products. At the same time, hydrogen peroxide can also be bonded to the network structure through hydrogen bonds, and at the same time citric acid can chelate with sodium hydroxide and dipotassium hydrogen phosphate to make it contact with the cotton products, realizing functions such as oxidation and bleaching.

[0024] Hydrogen peroxide generates HOO - under alkaline conditions, which can oxidize the chromogenic system in pigments to achieve decolorization. The alkaline conditions can also trigger hydrogen peroxide to generate free radicals, thereby destroying the double bonds in the molecular structures of pectin substances, waxes and nitrogen-containing substances, reducing the intermolecular forces between them in the cellulose fibers and removing them, that is, realizing the oxidation and bleaching of impurities such as pectin substances. During the high-temperature soaping process, the swelling, oxidation and bleaching reactions continue to proceed rapidly. At the same time, high-temperature soaping can chemically degrade the oxidation products, and impurities such as pectin acid esters are saponified into sodium salts and then removed through subsequent washing.

[0025] (2) The synergistic effects of various substances in the mixed auxiliary agent of the present invention and the synergistic effects of various substances in the alkali-oxygen solution not only make the bleaching effect better, but also the network structure formed between various substances in the mixed auxiliary agent can encapsulate sodium hydroxide and hydrogen peroxide, making hydrogen peroxide more stable and avoiding the decomposition of hydrogen peroxide in the alkali agent caused by impregnating and rolling the mixed solution of alkali agent and hydrogen peroxide in the conventional one-step method; at the same time, ethanol can act as a stabilizer for hydrogen peroxide, further improving the stability of the alkali-oxygen solution.

[0026] (3) The present invention uses an ethanol / water system instead of a pure water system. After ethanol is extracted and recovered, it can be reused, increasing the utilization rate of ethanol and saving the water consumption, which is conducive to water conservation and emission reduction. Detailed implementation methods

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail below in conjunction with specific embodiments.

[0028] In addition, it should also be noted that the term "comprising", "including", or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article, or device.

[0029] The present invention provides a cold pad-batch debleaching method for cotton, comprising the following steps:

[0030] S1. Padding:

[0031] First, dissolve a preset mass of sodium hydroxide in a preset mass of water, stir to dissolve it; then add it to a preset mass of ethanol, stir to dissolve it; then add dipotassium hydrogen phosphate thereto, stir to dissolve; finally add a mixed auxiliary agent, and mix evenly to obtain an alkali-oxygen solution. Specifically, the concentration of hydrogen peroxide in the alkali-oxygen solution is 5-15 g / L, the concentration of sodium hydroxide is 8-16 g / L, the concentration of dipotassium hydrogen phosphate is 5-7 g / L, the concentration of the mixed auxiliary agent is 1-2 g / L, and the volume ratio of ethanol to water is 80%:20% - 60%:40%.

[0032] The mixed auxiliary agent is an aqueous mixed solution of fatty alcohol polyoxyethylene 6-15EO (CAS No. 9043-30-5, where 6-15EO means containing 6-15 moles of ethylene oxide), diethylene glycol monobutyl ether (CAS No. 112-34-5), branched and linear C13-15 alcohol ethoxylate 7EO (CAS No. 157627-86-6, where 7EO means containing 7 moles of ethylene oxide), branched and linear C13-15 alcohol ethoxylate 5EO (CAS No. 157627-86-6, where 5EO means containing 5 moles of ethylene oxide), citric acid monohydrate (CAS No. 5949-29-1), 2-methyl-3(2H)-isothiazolinone (CAS No. 2682-20-4), and isotridecanol (CAS No. 27458-92-0); the mass concentration of fatty alcohol polyoxyethylene 6-15EO in the mixed auxiliary agent is 15%-20%, the mass concentration of diethylene glycol monobutyl ether is 5%-10%, the mass concentration of branched and linear C13-15 alcohol ethoxylate 7EO is 5%-10%, the mass concentration of branched and linear C13-15 alcohol ethoxylate 5EO is 5%-10%, the mass concentration of citric acid monohydrate is 1%-5%, the mass concentration of 2-methyl-3(2H)-isothiazolinone is 0.0015%-0.01%, and the mass concentration of isotridecanol is 0.1%-1%.

[0033] In a one-dip-and-one-roll manner, the cotton product is impregnated and rolled in an alkali-oxygen solution with a preset concentration, the liquor pickup rate is 120%-200%, and the impregnation and rolling temperature is 20-25°C. The cotton product is one of cotton fabric and cotton non-woven fabric.

[0034] Cotton products generally contain impurities such as sizing agents, pectin substances, cottonseed hulls, oils, waxes, nitrogen-containing substances, and pigments. In this process, the cotton product is impregnated in the alkali-oxygen solution. Firstly, an appropriate amount of ethanol can reduce the surface tension between the cotton product and the solution, making the cotton product have excellent wettability in the alkali-oxygen solution, so that a large amount of alkali-oxygen solution adheres to the surface of the cotton product; secondly, ethanol has the characteristic of high permeability, so that the alkali-oxygen solution can quickly enter the interior of the cotton product; thirdly, ethanol can act as a stabilizer for hydrogen peroxide, on the one hand, reducing the use of stabilizers, and on the other hand, making the alkali-oxygen solution more stable.

[0035] In addition, in the mixed auxiliary agent, the long-chain structure of fatty alcohol polyethyleneglycol 6-15EO contains rich ether groups and hydroxyl groups, the short molecular chain of diethylene glycol monobutyl ether also contains ether groups and hydroxyl groups, the branched and straight-chain C13-15 alcohol ethoxylates 7EO and the branched and straight-chain C13-15 alcohol ethoxylates 5EO have longer molecular chains, the citric acid monohydrate molecule contains carboxyl groups and hydroxyl groups and can chelate well with metals, the 2-methyl-3(2H)-isothiazolinone cyclic compound contains nitrogen atoms and oxygen atoms, and isodecyl alcohol contains hydroxyl groups and long chains. Different degrees of cross-linking and entanglement occur between the long-chain compounds, short-chain compounds and cyclic compounds in the mixed auxiliary agent, and they are bonded to each other through hydrogen bonds to form a special network structure. Based on the high permeability of ethanol, this network structure adheres to the surface of the cotton fabric and bonds with the cotton product through hydrogen bonds; secondly, this network structure can wrap sodium hydroxide, hydrogen peroxide and dipotassium hydrogen phosphate, so that sodium hydroxide, hydrogen peroxide and dipotassium hydrogen phosphate are in firm contact with the cotton product, realizing functions such as oxidation and bleaching. At the same time, hydrogen peroxide can also be bonded to the network structure through hydrogen bonds, and at the same time citric acid can chelate with sodium hydroxide and dipotassium hydrogen phosphate to make them contact with the cotton product; thirdly, this network structure can wrap sodium hydroxide and hydrogen peroxide, making hydrogen peroxide more stable, avoiding the decomposition of hydrogen peroxide in the alkali agent when impregnating and rolling the mixed solution of alkali agent and hydrogen peroxide in the conventional one-step method, and enhancing the bleaching effect.

[0036] When the alkali-oxygen solution enters the interior of the cotton product, hydrogen peroxide generates HOO - under alkaline conditions, which can oxidize the chromogenic system in the pigment to achieve color removal. The alkaline conditions can also cause hydrogen peroxide to generate free radicals, thereby destroying the double bonds in the molecular structures of pectin substances, waxes and nitrogen-containing substances, reducing the intermolecular forces between them in the cellulose fibers and removing them, that is, realizing the oxidation and bleaching of impurities such as pectin substances (oxidation and bleaching accompany the whole cold pad-batch desizing and bleaching process).

[0037] S2. Coiling and stacking:

[0038] The cotton products after padding in step S1 are first placed on a coiling machine for coiling, and then wrapped with plastic film and stacked while rotating at a constant speed. Among them, the stacking temperature is 20 - 25 °C, the stacking time is 12 - 24 h; the rotation speed of the constant rotation is 5 - 10 r / min.

[0039] During this process, the alkali-oxygen solution on the surface and inside of the cotton products is further evenly distributed. During this process, swelling, oxidation, and bleaching continue, and at the same time, favorable conditions are provided for the subsequent washing and drying processes.

[0040] S3. Washing and drying:

[0041] The cotton products after coiling and stacking in step S2 are successively subjected to soaping, hot water washing, cold water washing, and drying to obtain the finished products. Specifically, the cotton products after coiling and stacking in step S2 are first soaped at 95 °C once, then washed with water at 95 °C once, and finally pickled once and dried. Soaping is carried out in a mixed aqueous solution of 5 g / L soap powder and 2 g / L sodium bicarbonate. Pickling is carried out in dilute sulfuric acid with a concentration of 0.2 - 0.3 g / L at room temperature.

[0042] During the high-temperature soaping process, the swelling, oxidation, and bleaching reactions continue to proceed rapidly. At the same time, high-temperature soaping can chemically degrade the oxidation products, and impurities such as pectin esters are saponified into sodium salts and then removed through subsequent washing.

[0043] The present invention will be described in detail below through specific embodiments.

[0044] Example 1

[0045] A cold pad-batch desizing and bleaching method for cotton includes the following steps:

[0046] S1. Padding:

[0047] First, a preset mass of sodium hydroxide is dissolved in a preset mass of water, and after stirring and dissolving; then it is added to a preset mass of ethanol, and after stirring and dissolving; then potassium hydrogen phosphate is added thereto, and after stirring and dissolving; finally, a mixed auxiliary agent is added thereto, and after mixing evenly, an alkali-oxygen solution is obtained. Specifically, the concentration of hydrogen peroxide in the alkali-oxygen solution is 10 g / L, the concentration of sodium hydroxide is 10 g / L, the concentration of potassium hydrogen phosphate is 6 g / L, the concentration of the mixed auxiliary agent is 2 g / L, the volume ratio of ethanol to water is 70%:30%, the ethanol dosage is 140 mL, and the water dosage is 60 mL.

[0048] In the mixed auxiliary agent, the mass concentration of fatty alcohol polyoxyethylene 6 - 15EO is 18%, the mass concentration of diethylene glycol monobutyl ether is 8%, the mass concentration of branched and linear C13 - 15 alcohol ethoxylate 7EO is 8%, the mass concentration of branched and linear C13 - 15 alcohol ethoxylate 5EO is 8%, the mass concentration of citric acid monohydrate is 3%, the mass concentration of 2 - methyl - 3(2H)-isothiazolinone is 0.0055%, and the mass concentration of isotridecanol is 0.5%.

[0049] Adopt the method of one - dip and one - nip. Immerse and nip the cotton non - woven fabric in the alkali - oxygen solution with a preset concentration. The liquor pickup rate is 160%, and the immersion and niping temperature is 25°C.

[0050] S2. Coiling and stacking:

[0051] First, place the cotton non - woven fabric after being immersed and nipped in step S1 on a coiling machine for coiling, and then wrap the coiled cotton non - woven fabric with a plastic film and rotate it evenly for stacking. Among them, the stacking temperature is 25°C, the stacking time is 24h; the rotation speed of the uniform rotation is 8r / min.

[0052] S3. Washing and drying:

[0053] The cotton non - woven fabric after being coiled and stacked in step S2 is successively subjected to soaping, hot water washing, cold water washing and drying to obtain the finished product. Specifically, the cotton non - woven fabric after being coiled and stacked in step S2 is first soaped once at 95°C, then washed once at 95°C, and finally pickled once and dried. The soaping is carried out in a mixed aqueous solution of 5g / L soap powder and 2g / L sodium bicarbonate. The pickling is carried out in dilute sulfuric acid with a concentration of 0.25g / L at room temperature.

[0054] Examples 2 - 3 and Comparative Examples 1 - 2

[0055] A cold pad - batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the concentration of the mixed auxiliary agent is different, and the others are substantially the same as those in Example 1, which will not be elaborated here.

[0056] The cotton non - woven fabrics obtained in Examples 1 - 3 and Comparative Examples 1 - 2 were subjected to performance tests, and the results are shown in Table 1:

[0057] The whiteness was determined with reference to the standard GB / T 8424.2 - 2001 "Textiles - Tests for colour fastness - Instrumental assessment of relative whiteness".

[0058] The longitudinal strength of the cotton non - woven fabric before treatment is 41.5N.

[0059] Table 1 Related properties of the cotton non - woven fabrics obtained in Examples 1 - 3 and Comparative Examples 1 - 2

[0060] Examples Mixed Auxiliary Agent (g / L) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 2 94.17 1.95 99.0 Example 2 1.5 93.87 2.10 80.0 Example 3 2.5 94.09 2.23 78.5 Comparative Example 1 1 93.56 2.55 77.6 Comparative Example 2 3 94.15 1.95 74.2

[0061] As can be seen from Table 1, within a certain range, as the concentration of the mixed auxiliary agent increases (Examples 1, 2, and 3), the whiteness of the cotton non-woven fabric first increases and then basically stabilizes, the water absorption time first decreases and then increases, and the longitudinal strength first increases and then decreases. This may be because as the concentration of the mixed auxiliary agent increases, the network structure formed by the bonding of various components in the mixed auxiliary agent tightly combines with a larger number of sodium hydroxide, hydrogen peroxide, and dipotassium hydrogen phosphate, resulting in a better bleaching effect; a relatively large amount of sodium hydroxide and hydrogen peroxide may cause certain damage to the cotton non-woven fabric, so the longitudinal strength decreases. However, compared with the longitudinal strength of the original cotton non-woven fabric before treatment, the longitudinal strength of the treated cotton non-woven fabric has increased significantly. This is because on the one hand, waxes and the like on the surface of the cotton fibers are removed, enhancing the friction between the fibers; on the other hand, various substances in the mixed auxiliary agent interact with the cotton non-woven fabric, thereby significantly increasing its longitudinal strength. The change in the water absorption time is mainly due to the change in the concentration of the mixed auxiliary agent, which causes differences in the surface structure of the cotton non-woven fabric and the distribution of hydroxyl groups on the surface of the cotton fibers. However, the overall water absorption time is short, and the water absorption of the cotton non-woven fabric is good.

[0062] When the concentration of the mixed auxiliary agent is too low (Comparative Example 1), the treatment effect on various impurities in the fiber is not good, and the whiteness and longitudinal strength of the obtained cotton non-woven fabric are relatively low, and the water absorption is relatively poor.

[0063] When the concentration of the mixed auxiliary agent is too high (Comparative Example 2), the increase in whiteness is not obvious, and the longitudinal strength decreases.

[0064] Examples 4 - 5 and Comparative Examples 3 - 4

[0065] A cold pad-batch stripping and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the concentration of dipotassium hydrogen phosphate is different, and the others are substantially the same as in Example 1, so they will not be elaborated here.

[0066] The cotton non-woven fabric products obtained in Examples 4 - 5 and Comparative Examples 3 - 4 were subjected to performance tests, and the results are shown in Table 2:

[0067] Table 2 Related properties of the cotton non-woven fabrics obtained in Examples 4 - 5 and Comparative Examples 3 - 4

[0068] Examples Dipotassium Hydrogen Phosphate (g / L) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 6 94.17 1.95 99.0 Example 4 5 93.51 2.35 95.1 Example 5 7 94.01 2.04 94.6 Comparative Example 3 4 92.89 2.56 91.8 Comparative Example 4 8 93.33 2.37 92.4

[0069] As can be seen from Table 2, within a certain range, as the concentration of dipotassium hydrogen phosphate increases (Examples 1, 4, and 5), the whiteness of the cotton non-woven fabric first increases and then decreases, the water absorption time first decreases and then increases slightly, and the longitudinal strength first increases and then decreases. This indicates that there is a certain synergistic effect between dipotassium hydrogen phosphate and the mixed additives. The change in the concentration of dipotassium hydrogen phosphate will affect the intermolecular bonding structure of the mixed additives with sodium hydroxide, hydrogen peroxide, and dipotassium hydrogen phosphate, thereby affecting the impurity removal and bleaching reactions and ultimately affecting the performance of the cotton non-woven fabric.

[0070] When the concentration of dipotassium hydrogen phosphate is too low (Comparative Example 3), it cannot play a good synergistic and promoting role, resulting in relatively low performance of the cotton non-woven fabric.

[0071] When the concentration of dipotassium hydrogen phosphate is too high (Comparative Example 4), the whiteness, water absorption, and longitudinal strength all decrease. This may be because when the concentration of dipotassium hydrogen phosphate is too high, it occupies too many pores in the network structure formed by the mixed additives, resulting in less bonding between sodium hydroxide and hydrogen peroxide, and the structure formed by each substance is not uniform at this time, ultimately affecting the performance of the cotton.

[0072] Examples 6 - 7 and Comparative Examples 5 - 6

[0073] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the mass concentration of branched and linear C13 - 15 alcohol ethoxylate 7EO (abbreviated as 7EO) in the mixed additives is different, and the others are roughly the same as in Example 1, which will not be elaborated here.

[0074] The cotton non-woven fabrics obtained from Examples 6 - 7 and Comparative Examples 5 - 7 were subjected to performance tests, and the results are shown in Table 3:

[0075] Table 3 Related properties of the cotton non-woven fabrics obtained from Examples 6 - 7 and Comparative Examples 5 - 7

[0076] Examples 7EO (%) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 8 94.17 1.95 99.0 Example 6 5 92.12 2.98 90.8 Example 7 10 93.43 2.24 92.4 Comparative Example 5 4 90.33 3.12 88.4 Comparative Example 6 12 93.56 2.13 89.6 Comparative Example 7 0 86.45 3.49 88.6

[0077] As can be seen from Table 3, within a certain range, as the mass concentration of 7EO in the mixed additives increases (Examples 1, 6, and 7), the whiteness of the cotton non-woven fabric first increases and then decreases, the water absorption time first decreases and then increases slightly, and the longitudinal strength first increases and then decreases. This is mainly because as the content of 7EO in the mixed additives changes, different numbers and positions of ethylene oxide will affect the network structure formed by the bonding of long-chain compounds, short-chain compounds, and cyclic compounds in the mixed additives, thereby affecting various properties.

[0078] When the content of 7EO is too low (Comparative Example 5) or even when it contains no 7EO (Comparative Example 7), various properties of the cotton non-woven fabric significantly decline, indicating that there is a certain synergistic effect among the substances in the mixed auxiliary agent. At the same time, it shows that when the contents of the substances in the mixed auxiliary agent are within a mutually matching range, the synergistic effect is optimal.

[0079] When the content of 7EO is too high (Comparative Example 6), there is no obvious improvement in whiteness, and both water absorbency and longitudinal strength decline.

[0080] Examples 8 - 9 and Comparative Examples 8 - 10

[0081] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the mass concentration of branched and linear C13 - 15 alcohol ethoxylate 5EO (abbreviated as 5EO) in the mixed auxiliary agent is different, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0082] The cotton non-woven fabrics obtained from Examples 8 - 9 and Comparative Examples 8 - 10 were subjected to performance tests, and the results are shown in Table 4:

[0083] Table 4 Related properties of the cotton non-woven fabrics obtained from Examples 8 - 9 and Comparative Examples 8 - 10

[0084] Examples 5EO (%) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 8 94.17 1.95 99.0 Example 8 5 91.96 2.57 95.3 Example 9 10 93.22 2.02 95.5 Comparative Example 8 4 88.79 3.13 85.1 Comparative Example 9 12 94.11 2.13 91.2 Comparative Example 10 0 85.34 3.56 85.6

[0085] As can be seen from Table 4, within a certain range, as the mass concentration of 5EO in the mixed auxiliary agent increases (Examples 1, 8, 9), the whiteness of the cotton non-woven fabric first increases and then decreases, the water absorption time first decreases and then increases slightly, and the longitudinal strength first increases and then decreases. This shows that the change in the content of 5EO in the mixed auxiliary agent will also affect the network structure formed by the bonding of long-chain compounds, short-chain compounds, and cyclic compounds in the mixed auxiliary agent, thereby affecting various properties.

[0086] The data of Comparative Example 8 and Comparative Example 10 further illustrate that there is a certain synergistic effect among the substances in the mixed auxiliary agent.

[0087] Examples 10 - 11 and Comparative Examples 11 - 12

[0088] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the mass concentration of 2-methyl-3(2H)-isothiazolinone in the mixed auxiliary agent is different, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0089] The cotton non-woven fabrics obtained from Examples 10 - 11 and Comparative Examples 11 - 12 were subjected to performance tests, and the results are shown in Table 5:

[0090] Table 5 Related properties of the cotton non-woven fabrics obtained from Examples 10 - 11 and Comparative Examples 11 - 12

[0091]

[0092]

[0093] As can be seen from Table 5, from the data of Examples 1, 10, and 11, even if the content of 2-methyl-3(2H)-isothiazolone in the mixed auxiliary agent is very small, the change in its content will still affect the impurity removal and bleaching effects of cotton, and further affect its performance.

[0094] When the mixed auxiliary agent does not contain 2-methyl-3(2H)-isothiazolone (Comparative Example 11), the various properties of the cotton non-woven fabric are relatively low. This is mainly because the cyclic 2-methyl-3(2H)-isothiazolone can effectively promote the entanglement between different chain compounds in the mixed auxiliary agent, thereby affecting the mutual combination and interaction strength of sodium hydroxide and hydrogen peroxide with the cotton non-woven fabric, and ultimately affecting the performance of the cotton non-woven fabric.

[0095] When the content of 2-methyl-3(2H)-isothiazolone in the mixed auxiliary agent is too high (Comparative Example 12), the cyclic 2-methyl-3(2H)-isothiazolone has a certain hindering effect on the entanglement between different chain compounds in the mixed auxiliary agent, ultimately affecting the performance of the cotton non-woven fabric.

[0096] Examples 12 - 13 and Comparative Examples 13 - 14

[0097] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the mass concentration of isotridecanol in the mixed auxiliary agent is different, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0098] The cotton non-woven fabrics obtained from Examples 12 - 13 and Comparative Examples 13 - 14 were subjected to performance tests, and the results are shown in Table 6:

[0099] Table 6 Related properties of the cotton non-woven fabrics obtained from Examples 12 - 13 and Comparative Examples 13 - 14

[0100] Examples Mixed Auxiliary Agent (g / L) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 0.5 94.17 1.95 99.0 Example 12 0.1 92.21 2.78 92.6 Example 13 1 92.06 2.35 94.8 Comparative Example 13 0 90.32 3.24 90.6 Comparative Example 14 1.5 92.17 2.33 95.9

[0101] As can be seen from Table 6, within a certain range, with the change in the mass concentration of isotridecanol in the mixed auxiliary agent (Examples 1, 12, 13), the various properties of the cotton non-woven fabric change. This is mainly because isotridecanol with a relatively short chain length will affect the network structure formed by the bonding between long-chain compounds, short-chain compounds, and cyclic compounds in the mixed auxiliary agent, further illustrating the synergistic effect between various substances in the mixed auxiliary agent.

[0102] When the mixed auxiliary agent does not contain isotridecanol (Comparative Example 13), it will affect the performance of the cotton non-woven fabric.

[0103] As the content of isodecyl alcohol in the mixed auxiliary agent further increases (Comparative Example 14), the whiteness, water absorbency, and longitudinal strength of the cotton non-woven fabric basically tend to be stable.

[0104] Examples 14 - 15 and Comparative Examples 15 - 16

[0105] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the concentration of sodium hydroxide is different, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0106] The cotton non-woven fabrics obtained from Examples 14 - 15 and Comparative Examples 15 - 16 were subjected to performance tests, and the results are shown in Table 7:

[0107] Table 7 Related properties of the cotton non-woven fabrics obtained from Examples 14 - 15 and Comparative Examples 15 - 16

[0108] Examples Sodium Hydroxide (g / L) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 10 94.17 1.95 99.0 Example 14 8 92.77 2.87 96.3 Example 15 16 91.58 3.66 81.8 Comparative Example 15 6 90.32 3.14 94.3 Comparative Example 16 20 91.46 3.89 78.6

[0109] As can be seen from Table 7, the content of sodium hydroxide has an impact on the performance of the cotton non-woven fabric. When the concentration of sodium hydroxide is relatively low, the whiteness of the cotton non-woven fabric is relatively low, and the water absorption time is relatively long. As the content of sodium hydroxide increases, the pH of the solution increases accordingly, and other components in the solution are more likely to enter the fiber interior and react with it. The performance of the cotton non-woven fabric becomes better and better, and when its concentration reaches 10 g / L, the effect is the best. Continuing to increase the sodium hydroxide concentration will instead damage the fiber and lead to a worse effect.

[0110] Examples 16 - 17 and Comparative Examples 17 - 18

[0111] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the concentration of hydrogen peroxide is different, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0112] The cotton non-woven fabrics obtained from Examples 16 - 17 and Comparative Examples 17 - 18 were subjected to performance tests, and the results are shown in Table 8:

[0113] Table 8 Related properties of the cotton non-woven fabrics obtained from Examples 16 - 17 and Comparative Examples 17 - 18

[0114] Examples Hydrogen Peroxide (g / L) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 10 94.17 1.95 99.0 Example 16 5 89.98 2.87 90.8 Example 17 15 92.39 2.72 92.6 Comparative Example 17 3 88.43 3.50 84.5 Comparative Example 18 20 93.47 3.72 81.3

[0115] As can be seen from Table 8, the content of hydrogen peroxide has an impact on the performance of the cotton non-woven fabric. When the concentration of hydrogen peroxide is relatively low, the whiteness of the cotton non-woven fabric is relatively low, and the water absorption time is relatively long. As the content of hydrogen peroxide increases, its performance becomes better and better, and when its concentration reaches 10 g / L, the effect is the best. Continuing to increase the hydrogen peroxide concentration has not much impact on the whiteness of the finished product, while the water absorbency and longitudinal strength continuously decrease.

[0116] Examples 18 - 19 and Comparative Examples 19 - 20

[0117] A cold pad - batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the volume ratio of ethanol to water is different, and the others are substantially the same as those in Example 1, which will not be elaborated here.

[0118] The cotton non - woven fabrics obtained from Examples 18 - 19 and Comparative Examples 19 - 20 were subjected to performance tests, and the results are shown in Table 9:

[0119] Table 9 Related properties of the cotton non - woven fabrics obtained from Examples 18 - 19 and Comparative Examples 19 - 20

[0120]

[0121]

[0122] As can be seen from Table 9, the volume ratio of ethanol to water has an impact on the properties of the cotton non - woven fabric. This may be because, with the change of the volume ratio of ethanol to water, the infiltration and swelling of the cotton by the alkali - oxygen solution are affected, and at the same time, the interaction between various substances and the cotton is affected, thus affecting the properties of the cotton non - woven fabric. Through experimental comparison, it is found that when ethanol: water = 70:30, the whiteness and water absorption time reach the best.

[0123] Examples 20 - 21 and Comparative Examples 21 - 22

[0124] A cold pad - batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the liquor pickup rate is different, and the others are substantially the same as those in Example 1, which will not be elaborated here.

[0125] The cotton non - woven fabrics obtained from Examples 20 - 21 and Comparative Examples 21 - 22 were subjected to performance tests, and the results are shown in Table 10:

[0126] Table 10 Related properties of the cotton non - woven fabrics obtained from Examples 20 - 21 and Comparative Examples 21 - 22

[0127] Examples Liquid Uptake Rate (%) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 160 94.17 1.95 99.0 Example 20 120 93.43 2.36 91.5 Example 21 200 94.05 2.22 93.5 Comparative Example 21 100 92.54 2.87 90.2 Comparative Example 22 250 94.13 2.15 91.4

[0128] As can be seen from Table 10, the liquor pickup rate has an impact on the properties of the cotton non - woven fabric. When the liquor pickup rate is small, the content of the finishing liquor on the cotton non - woven fabric is less, and it cannot fully react with the impurities on the cotton, resulting in lower whiteness and longer water absorption time. When the liquor pickup rate reaches 160%, there is sufficient finishing liquor on the cotton non - woven fabric to react with the cotton impurities, and at this time, the whiteness and water absorption time reach the best. With the further increase of the liquor pickup rate, the impact on the whiteness is not significant.

[0129] Example 22 and Comparative Examples 23 - 24

[0130] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the stacking time is different, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0131] The cotton non-woven fabrics obtained in Example 22 and Comparative Examples 23-24 were subjected to performance tests, and the results are shown in Table 11:

[0132] Table 11 Related properties of the cotton non-woven fabrics obtained in Example 22 and Comparative Examples 23-24

[0133] Examples Stacking Time (h) Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Example 1 24 94.17 1.95 99.0 Example 22 12 91.41 2.88 92.8 Comparative Example 23 10 91.13 2.93 93.5 Comparative Example 24 30 93.97 2.15 96.3

[0134] As can be seen from Table 11, the stacking time has an impact on the properties of cotton. When the stacking time is short, the impurities on the cotton non-woven fabric do not react sufficiently with the finishing liquid, resulting in lower whiteness and longer water absorption time. When the stacking time reaches 24 h, the finishing liquid reacts sufficiently with the cotton impurities, and at this time, the whiteness and water absorption time reach the best. With the further increase of the stacking time, the caustic oxygen solution pit causes certain damage to the cotton, thereby affecting its properties.

[0135] Comparative Example 25

[0136] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the mixed auxiliary agent does not contain branched and linear C13-15 alcohol ethoxylate 7EO, branched and linear C13-15 alcohol ethoxylate 5EO, 2-methyl-3(2H)-isothiazolinone, and isodecyl alcohol, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0137] Comparative Example 26

[0138] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the mixed auxiliary agent does not contain fatty alcohol polyethyl ether 6-15EO, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0139] Comparative Example 27

[0140] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the branched and linear C13-15 alcohol ethoxylate 7EO in the mixed auxiliary agent is changed to penetrant JFC, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0141] Comparative Example 28

[0142] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the branched and linear C13-15 alcohol ethoxylate 7EO and the branched and linear C13-15 alcohol ethoxylate 5EO in the mixed auxiliary agent are respectively changed to the branched and linear C8-10 alcohol ethoxylate 7EO and the branched and linear C8-10 alcohol ethoxylate 5EO. The others are substantially the same as those in Example 1 and will not be elaborated here.

[0143] Comparative Example 29

[0144] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, the branched and linear C13-15 alcohol ethoxylate 7EO and the branched and linear C13-15 alcohol ethoxylate 5EO in the mixed auxiliary agent are respectively changed to the branched and linear C16-18 alcohol ethoxylate 7EO and the branched and linear C16-18 alcohol ethoxylate 5EO. The others are substantially the same as those in Example 1 and will not be elaborated here.

[0145] Comparative Example 30

[0146] A cold pad-batch desizing and bleaching method for cotton. Compared with Example 1, the difference lies in that in step S1, dipotassium hydrogen phosphate is replaced with potassium monopersulfate compound salt. The others are substantially the same as those in Example 1 and will not be elaborated here.

[0147] The cotton non-woven fabrics obtained in Comparative Examples 25-30 were subjected to performance tests, and the results are shown in Table 12:

[0148] Table 12 Related properties of the cotton non-woven fabrics obtained in Comparative Examples 25-30

[0149] Examples Whiteness (%) Water Absorption Time (s) Longitudinal Tensile Strength (N) Comparative Example 25 89.47 2.97 95.3 Comparative Example 26 92.15 2.87 94.8 Comparative Example 27 89.46 2.13 96.1 Comparative Example 28 92.42 2.56 88.6 Comparative Example 29 92.77 2.81 81.4 Comparative Example 30 93.44 2.17 89.9

[0150] As can be seen from Table 12, after various substances in the mixed auxiliary agent are replaced or omitted, the whiteness and water absorption time of the cotton non-woven fabric cannot reach the level of the original mixed auxiliary agent, indicating that there is a synergistic effect among various substances in the mixed auxiliary agent of the present invention, and each substance plays an irreplaceable role.

[0151] In summary, the present invention provides a cold pad-batch desizing and bleaching method for cotton. By preparing an alkali-oxygen solution of ethanol, water, sodium hydroxide, hydrogen peroxide and a mixed auxiliary agent in a suitable proportion, and at the same time controlling the proportion of each substance in the mixed auxiliary agent, a special network structure is formed among the mixed auxiliary agents, so that sodium hydroxide and hydrogen peroxide are firmly attached to the surface and inside of the cotton product. Through the synergistic effect of various substances in the mixed auxiliary agent and the synergistic effect of various substances in the alkali-oxygen solution, the performance of the finished product obtained by cold pad-batch desizing and bleaching is better; the present invention uses an ethanol / water system instead of a pure water system, and the ethanol can be recovered and reused after extraction, increasing the utilization rate of ethanol and saving the water consumption, which is conducive to water conservation and emission reduction.

[0152] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A cold pad-batch desizing and bleaching method for cotton, characterized in that, it comprises the following steps: S1. Padding: Padding the cotton product in an alkali-oxygen solution with a preset concentration; the alkali-oxygen solution is an ethanol-water mixed solution composed of hydrogen peroxide, sodium hydroxide, dipotassium hydrogen phosphate and a mixed auxiliary agent, and the mixed auxiliary agent is a mixed aqueous solution of fatty alcohol polyoxyethylene ether 6-15EO, diethylene glycol monobutyl ether, branched and linear C13-15 alcohol ethoxylate 7EO, branched and linear C13-15 alcohol ethoxylate 5EO, citric acid monohydrate, 2-methyl-3(2H)-isothiazolinone and isotridecanol; the concentration of hydrogen peroxide in the alkali-oxygen solution is 5-15 g / L, the concentration of sodium hydroxide is 8-16 g / L, the concentration of dipotassium hydrogen phosphate is 5-7 g / L, the concentration of the mixed auxiliary agent is 1-2 g / L, and the volume ratio of ethanol to water is 80%:20% - 60%:40%; the mass concentration of fatty alcohol polyoxyethylene ether 6-15EO in the mixed auxiliary agent is 15%-20%, the mass concentration of diethylene glycol monobutyl ether is 5%-10%, the mass concentration of branched and linear C13-15 alcohol ethoxylate 7EO is 5%-10%, the mass concentration of branched and linear C13-15 alcohol ethoxylate 5EO is 5%-10%, the mass concentration of citric acid monohydrate is 1%-5%, the mass concentration of 2-methyl-3(2H)-isothiazolinone is 0.0015%-0.01%, and the mass concentration of isotridecanol is 0.1%-1%; S2. Coiling and piling: First coil the cotton product after padding in step S1, then wrap it with a plastic film and pile it up while rotating at a constant speed; S3. Washing and drying: The cotton product after coiling and piling in step S2 is successively subjected to soaping, hot water washing, cold water washing and drying to obtain the finished product.

2. The cold pad-batch desizing and bleaching method for cotton according to claim 1, characterized in that, in step S1, padding is carried out by one padding and one rolling, the liquor pickup rate is 120%-200%, and the padding temperature is 20-25°C.

3. The cold pad-batch desizing and bleaching method for cotton according to claim 1, characterized in that, in step S2, the temperature of the piling is 20-25°C, the piling time is 12-24 h; the rotation speed of the constant-speed rotation is 5-10 r / min.

4. The cold pad-batch desizing and bleaching method for cotton according to claim 1, characterized in that, step S3 is specifically: The cotton product after coiling and piling in step S2 is first soaped at 95°C once, then washed with water at 95°C once, and finally pickled once.

5. The cold pad-batch desizing and bleaching method for cotton according to claim 4, characterized in that, the soaping is carried out in a mixed aqueous solution of 5 g / L of soap powder and 2 g / L of sodium bicarbonate.

6. The cold pad-batch desizing and bleaching method for cotton according to claim 1, characterized in that, the cotton product is a cotton fabric.

7. The cold pad-batch desizing and bleaching method for cotton according to claim 1, characterized in that, the whiteness of the obtained finished product is as high as 94.17; the longitudinal strength is as high as 99.0 N; the water absorption time is as low as 1.95 s.

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