A high whiteness bleaching process for cotton fabrics, cotton fabrics produced therefrom and uses thereof

Abstract

The application provides a high-whiteness bleaching process of cotton fabric, cotton fabric prepared by the process and application, and belongs to the field of textile fabric dyeing and finishing. The process comprises: under the condition of ≤100 DEG C and alkalinity, one-step bleaching and whitening bath treatment is performed on cotton fabric which has been pretreated by a scouring agent and an organic acid complexing agent. The bleaching agent in the one-step bleaching and whitening bath treatment is hydrogen peroxide. The application can effectively remove metal ions in the fabric by pretreatment with a scouring agent and an organic acid complexing agent before bleaching and whitening bath, avoid the influence of metal ions on the effective decomposition of hydrogen peroxide in the bleaching and whitening bath, and adjust the decomposition efficiency of the bleaching agent, so that the bleaching effect can be ensured and the damage to the fiber can be reduced, that is, the whiteness of 150 or more is ensured while the weight loss rate is reduced, and the weight loss rate is controlled within 5%; and the one-step bleaching and whitening bath treatment of the application can be realized at a bleaching temperature below 100 DEG C, so that the energy consumption is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of dyeing and finishing of textile fabrics, and more particularly relates to a high-whiteness bleaching process for cotton fabrics, cotton fabrics prepared by the process and applications thereof. BACKGROUND

[0002] The bleaching process is a very important step in the production of white full-cotton knitted fabrics and full-cotton towels, and directly determines the quality of the products such as white full-cotton knitted fabrics and full-cotton towels. With the market share of white full-cotton knitted fabrics and full-cotton towels gradually reaching more than 20%, the improvement of the bleaching process becomes increasingly important.

[0003] In order to achieve higher whiteness, sodium silicate is often used as a stabilizer in the bleaching process, and the treatment temperature is even as high as 110°C. Although this treatment can increase the whiteness, the cylinder is prone to produce silicon scale during the bleaching process, which causes difficulty in cleaning. The high treatment temperature also increases the energy consumption, and the breaking strength and weight loss rate of the prepared product are also increased. As mentioned in patent CN 112195645 B, the conventional hydrogen peroxide high-temperature alkaline bleaching process has defects such as large damage to fabric strength. In the patent, a new type of hydrogen peroxide cold pad-batch bleaching process is disclosed. This method can avoid strength damage, but the whiteness can only reach about 83. Therefore, how to improve the bleaching effect of the conventional hydrogen peroxide high-temperature alkaline bleaching process is still very important. Some technologies propose to use a two-time oxygen bleaching process or a process flow of first reduction bleaching and then oxygen bleaching. The former also has problems of large strength loss and weight loss, while the latter mainly has defects of long process time, large process difficulty and large risk coefficient. SUMMARY

[0004] In view of the defects such as difficult further improvement of the bleaching effect of the hydrogen peroxide high-temperature alkaline bleaching process used in the production of white full-cotton knitted fabrics and full-cotton towels and the complexity of the process flow of other improved hydrogen peroxide high-temperature alkaline bleaching processes in the prior art, the purpose of the present application is to provide a high-whiteness bleaching process for cotton fabrics, cotton fabrics prepared by the process and applications thereof. The whiteness of the pure cotton fabric prepared by the bleaching process reaches 150 or more under specific pretreatment conditions, and the weight loss rate is controlled within 5%. Moreover, the bleaching process of the present application is a one-step bleaching process under the premise of using a silicon-free stabilizer at a temperature below 100°C. The bleaching process does not produce silicon scale in the cylinder, and the whiteness of the bleached fabric is high. The problems such as fabric strength loss and weight loss rate are significantly improved.

[0005] To achieve the above object, according to one aspect of the present application, a cotton fabric high-whiteness bleaching process is provided, comprising: performing one-step bleaching and whitening bath treatment on the cotton fabric pretreated by a scouring agent and an organic acid complexing agent under ≤100 ℃ and alkaline conditions, wherein the bleaching agent in the one-step bleaching and whitening bath treatment is hydrogen peroxide.

[0006] As a further preference, the pretreatment comprises: hot water bath treatment of the cotton fabric with the scouring agent and the organic acid complexing agent at a mass ratio of 0.2-0.7:1-5, and then washing.

[0007] As a further preference, the pretreatment comprises: first adding the cotton fabric into a treatment liquid containing the scouring agent and the organic acid complexing agent at a temperature of 20-30 ℃ at a bath ratio of 1:8-1:15, then heating to 60-80 ℃ at a rate of 3-7 ℃ / min for 20-30 min, draining the liquid, and washing at 60-80 ℃; preferably, the pretreatment comprises: first adding the cotton fabric into a treatment liquid containing the scouring agent and the organic acid complexing agent at a temperature of 20-30 ℃ at a bath ratio of 1:8-1:15, then heating to 60-70 ℃ at a rate of 5-7 ℃ / min for 5-15 min, and then heating to 70-80 ℃ at a rate of 3-5 ℃ / min for 15-25 min, draining the liquid, and washing at 60-80 ℃.

[0008] As a further preference, the scouring agent is the scouring agent TF-129HL concentrated by Transfar Intelligent Technology Co., Ltd., and / or the organic acid complexing agent is the mineral removal agent TF-510K by Transfar Intelligent Technology Co., Ltd.

[0009] As a further preference, the one-step bleaching and whitening bath treatment comprises: first adding the pretreated cotton fabric into a bleaching treatment liquid containing the scouring agent, the silicon-free stabilizer, and caustic soda at a temperature of 20-30 ℃ at a bath ratio of 1:8-1:15, running for 5-10 min, then adding hydrogen peroxide solution into the bleaching treatment liquid and running for 5-10 min, then continuously adding the whitening agent into the bleaching treatment liquid and heating to 98-100 ℃ at a rate of 5-10 ℃ / min for 45-60 min, then draining the liquid after cooling to 60-80 ℃ at a rate of 3-5 ℃ / min, and finally washing.

[0010] As a further preference, the specific process of washing in the one-step bleaching and whitening bath treatment is: first washing at 80-90 ℃, then draining the liquid and washing at 60-80 ℃, then draining the liquid and washing at 30-40 ℃, and finally adding acetic acid for neutralization and then draining the liquid.

[0011] As further preferably, the concentration of the refining agent in the bleaching treatment liquid is 0.2-0.7 g / L, the concentration of the silicon-free stabilizer is 0.2-0.4 g / L, the amount of the added caustic soda is 2-2.5 g / L, the amount of the added whitening agent is 0.1-0.3% (o.w.f), the concentration of the hydrogen peroxide solution is 25-35%, and the amount of the added hydrogen peroxide solution is 15-25 g / L, preferably, the whitening agent is whitening agent CPD.

[0012] As further preferably, the cotton fabric is pure cotton knitted fabric or pure cotton towel fabric, preferably, the cotton fabric is pure cotton knitted fabric.

[0013] According to another aspect of the present application, there is provided a cotton fabric produced by the above cotton fabric high-whiteness bleaching process.

[0014] According to still another aspect of the present application, there is provided a pure cotton T-pole, pure cotton towel or pure cotton bath towel produced by the above cotton fabric.

[0015] Overall, compared with the prior art, the above technical solution conceived by the present application has the following advantages

[0016] Advantages:

[0017] 1. The present application first pretreats the cotton fabric with a refining agent and an organic acid complexing agent, and then performs one-step bleaching and whitening bath treatment on the pretreated cotton fabric, wherein the pretreatment process can effectively avoid the invalid decomposition of the effective components of the bleaching agent in the one-step bleaching and whitening bath treatment, and adjust the decomposition rate of the bleaching agent, thereby ensuring the bleaching effect and reducing the damage to the fibers, i.e., reducing the weight loss rate while ensuring a whiteness of 150 or above, so that the weight loss rate is controlled within 5%; and the one-step bleaching and whitening bath treatment of the present application can be realized at a bleaching temperature of 100℃ or below, thereby greatly reducing energy consumption.

[0018] 2. The present application optimizes the mass ratio of the refining agent and the organic acid complexing agent, so as to ensure the best synergistic effect of the two, effectively reduce the difficulty of the organic acid complexing agent in the cotton fabric, and facilitate the subsequent treatment process.

[0019] 3. The present application uses a refining agent and an organic acid complexing agent for pretreatment, and can ensure the bleaching effect even in the case of using a silicon-free stabilizer, thereby avoiding the large production of silicon scale in the cylinder. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flow chart of the cotton fabric high-whiteness bleaching process provided by the embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0022] If a specific technique or condition is not specified in the examples, the technique or condition described in the literature in the art or according to the product manual is used. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be purchased through a regular channel.

[0023] As shown in Figure 1 According to one aspect of the present application, a high-whiteness bleaching process for cotton fabric is provided, which specifically comprises: pretreating the cotton fabric with a scouring agent and an organic acid complexing agent to remove metal ions in the cotton fabric fibers, thereby preparing for the effective decomposition of hydrogen peroxide in the next step; and then performing one-step bleaching and whitening bath on the pretreated fabric under ≤100℃ and alkaline conditions with hydrogen peroxide as the bleaching agent, which can achieve high-whiteness bleaching of the cotton fabric while minimizing the damage to the fibers caused by bleaching, and effectively reduce the processing temperature of the bleaching and whitening bath to achieve energy saving.

[0024] It is found in the experiments of the present application that the metal ions in the treatment liquid have a very important influence on the bleaching effect in the bleaching process for white cotton knitted fabric and cotton towel. When the content of metal ions is too high, not only the bleaching effective components used in the bleaching process cannot fully play their roles, but also a large amount of silicon scale will be generated in the cylinder due to the use of sodium silicate and other silicon-containing stabilizers. In actual production, metal ions cannot be completely removed. Therefore, through a large number of comparative experimental studies, it is found that when the scouring agent and the organic acid complexing agent are simultaneously added in the pretreatment stage, the bleaching and whitening of the white cotton knitted fabric and cotton towel can be achieved using no silicon stabilizer and a bleaching treatment temperature significantly lower than that of the prior art, and the whiteness value reaches above 150. At the same time, the strength damage and weight loss rate of the cotton fabric are effectively controlled by the synergistic effect of the scouring agent and the organic acid complexing agent. More importantly, the bleaching process flow of the present application is greatly simplified compared with the traditional two-step oxygen bleaching or the process flow of first reduction bleaching and then oxygen bleaching, and the improvement of the bleaching process for white cotton knitted fabric and cotton towel has great significance.

[0025] In addition, if the organic acid complexing agent in the present application is replaced by an inorganic acid such as hydrochloric acid or acetic acid, the performance of the cotton fabric will be reduced because the cotton fabric is extremely unstable under the conditions of inorganic acid and heat. The acid can cause the cellulose macromolecules to break and hydrolyze, resulting in a significant decrease in fiber strength, and also poses a great safety hazard to actual operation.

[0026] Further, the cotton fabric is treated by hot water bath and then washed after adding the refining agent and the organic acid complexing agent in a mass ratio of 0.2-0.7:1-5. It is found in the experiment that when the mass ratio of the refining agent and the organic acid complexing agent is 0.2-0.7:1-5, the synergistic effect of the two is the best. If the adding amount of the refining agent is too low, the grey fabric cannot be fully wetted, the difficulty of the organic acid complexing agent entering the cotton fabric is increased, and the complexation of the metal ions is weakened. With the increase of the content of the refining agent, the capillary effect of the cotton fabric is improved to a certain extent. If the adding amount of the refining agent is too high, the refining agent is attached to the surface of the cotton fabric in a large amount, which also increases the difficulty of the organic acid complexing agent entering the cotton fabric, is not conducive to the play of the organic acid complexing agent, and is also not conducive to the subsequent sewage treatment process. It is also found that when the refining agent is a non-ionic surfactant compound, a higher whiteness can be achieved with the least adding amount of the refining agent.

[0027] Further, the concentration of the organic acid complexing agent in the hot water bath is 1-5 g / L. The organic acid complexing agent has a strong removal capacity for metal ions such as iron, calcium and magnesium on the cotton fabric. When the concentration is controlled to be 1-5 g / L, the cotton fabric can achieve the best bleaching effect in one-step bleaching and whitening bath treatment.

[0028] Further, the cotton fabric is first added into the treatment liquid containing the refining agent and the organic acid complexing agent at a bath ratio of 1:8-1:15 and a temperature of 20-30 DEG C, then heated to 60-80 DEG C at a speed of 3-7 DEG C / min for 20-30 min, drained, and washed at 60-80 DEG C.

[0029] The staged heating method can also be used to promote the pretreatment effect of the refining agent and the organic acid complexing agent on the cotton fabric. Specifically, the cotton fabric is first added into the treatment liquid containing the refining agent and the organic acid complexing agent at a bath ratio of 1:8-1:15 and a temperature of 20-30 DEG C, then heated to 60-70 DEG C at a speed of 5-7 DEG C / min for 5-15 min, then heated to 70-80 DEG C at a speed of 3-5 DEG C / min for 15-25 min, drained, and washed at 60-80 DEG C.

[0030] Further, when the refining agent is the refining agent TF-129HL of Transfar Intelligent Technology Co., Ltd., the performance of the cotton fabric is better; and when the organic acid complexing agent is the refining agent TF-510K of Transfar Intelligent Technology Co., Ltd., the performance of the cotton fabric is better.

[0031] Further, the one-step bleaching and whitening bath treatment comprises the following steps: firstly, the pretreated cotton fabric is added into a bleaching treatment solution containing scouring agent, silicon-free stabilizer and caustic soda at a bath ratio of 1:8-1:15 and a temperature of 20-30 DEG C, and runs for 5-10 min; then hydrogen peroxide is added into the bleaching treatment solution and runs for 5-10 min; then a whitening agent is continuously added into the bleaching treatment solution and the temperature is raised to 98-100 DEG C at a speed of 5-10 DEG C / min and is kept for 45-60 min; then the temperature is lowered to 60-80 DEG C at a speed of 3-5 DEG C / min and the solution is discharged; finally, the cotton fabric is washed.

[0032] In the experiment, it is found that, compared with the shade lightening agent, the white lightening agent (such as the whitening agent CPD) must require that the bottom white of the cotton fabric reaches 85 or above during bleaching in order to achieve a whiteness of 150 or above, and it is very difficult to achieve a bleaching whiteness of 85, while the pretreatment of the cotton fabric according to the present application can make the bleaching whiteness of the pretreated cotton fabric reach 85, and the use of the white lightening agent can achieve a bleaching effect with a final whiteness of 150 or above.

[0033] Further, the concentration of each additive in the cotton fabric high-whiteness bleaching process is optimized, wherein the concentration of the scouring agent is 0.2-0.7 g / L, the concentration of the silicon-free stabilizer is 0.2-0.4 g / L, the amount of the caustic soda added is 2-2.5 g / L, the amount of the whitening agent added is 0.1-0.3% (o.w.f), the concentration of the hydrogen peroxide solution is 25-35%, and the amount of the hydrogen peroxide solution added is 15-25 g / L.

[0034] Further, the cotton fabric is pure cotton knitted fabric or pure cotton towel fabric, and preferably, the cotton fabric is pure cotton knitted fabric.

[0035] According to another aspect of the present application, a cotton fabric prepared by using the cotton fabric high-whiteness bleaching process is provided, and the whiteness of the cotton fabric reaches 150 or above.

[0036] According to still another aspect of the present application, the cotton fabric is used, which can be directly used as a finished product by a customer or can be used after functional finishing, and the cotton fabric is generally used for producing pure cotton T-shirt, pure cotton towel and pure cotton bath towel.

[0037] The technical solutions provided by the present application are further described below according to specific embodiments.

[0038] In the embodiment of the present application, the pure cotton knitted fabric to be treated is cotton fabric, the specification is 32S, and the gram weight is 180-190 g / m2 The pure cotton towel fabric to be treated is a pure cotton towel fabric.

[0039] The scouring agent TF-129HL, the mineral removal agent TF-510K and the whitening agent CPD in the embodiment of the application are all purchased from the company of Chuanhua Zhilian Co., Ltd.

[0040] The testing instrument for whiteness in the embodiment of the application is a colorimeter X-rite 7600, and CIE whiteness data is selected.

[0041] The calculation method of weight loss in the embodiment of the application is as follows: the initial mass of the cotton fabric after 24 hours of constant temperature and humidity before treatment is denoted as m0, the mass of the bleached cotton fabric after drying and 24 hours of constant temperature and humidity after bleaching is denoted as m1, and the calculation formula of weight loss is weight loss = (m0-m1) / m0*100%.

[0042] Example 1

[0043] A bleaching process of cotton fabric, the specific steps are as follows:

[0044] S1 water is added into the main cylinder of the dyeing cylinder and the pure cotton knitted fabric (bath ratio is 1:8), then 0.2 g / L of scouring agent TF-129HL and 2 g / L of mineral removal agent TF-510K are added from the auxiliary cylinder, and the mass ratio of the scouring agent TF-129HL and the mineral removal agent TF-510K is 0.1:1;

[0045] S2 the dyeing cylinder continues to run, and the temperature is raised to 80℃ at a speed of 5℃ / min, the liquid is directly discharged after running at 80℃ for 20 min, and then water at 60℃ is used for washing for 10 min to complete the pretreatment process;

[0046] S3 the bath ratio is kept as 1:8, 0.4 g / L of scouring agent TF-129HL and 0.2 g / L of stabilizer TF-122F are added from the auxiliary cylinder, 2.5 g / L of caustic soda is added, and then 18 g / L of hydrogen peroxide (30%) is added after running for 5 min, 0.3% (o.w.f) of whitening agent CPD is added after running for 5 min, the dyeing cylinder continues to run and the temperature is raised to 98℃ at a speed of 5℃ / min, the liquid is discharged after running at 98℃ for 45 min, and the temperature is reduced to 80℃ at a speed of 5℃ / min to discharge the liquid;

[0047] S4 the temperature of the water is raised to 80℃, the liquid is discharged after washing for 10 min, the water at 60℃ is added again, the liquid is discharged after washing for 10 min, and finally the water at 30℃ is added, the liquid is discharged after washing for 5 min, and the liquid is discharged after neutralization with acetic acid, to obtain the bleached cotton fabric.

[0048] The prepared pure cotton knitted fabric is dried and then the whiteness is tested, the CIE whiteness is 160, and the weight loss is 4.96%.

[0049] Comparative Example 1

[0050] A bleaching process of cotton fabric, the specific steps of which are basically the same as those of Example 1, except that no scouring agent TF-129HL is added in S1; the prepared pure cotton knitted fabric is dried and tested for whiteness, the CIE whiteness is 156, and the weight loss is 5.14%.

[0051] Comparative Example 2

[0052] A bleaching process of cotton fabric, the specific steps of which are basically the same as those of Example 1, except that no scouring agent TF-510K is added in S1; the prepared pure cotton knitted fabric is dried and tested for whiteness, the CIE whiteness is 148, and the weight loss is 5.21%.

[0053] Comparative Example 3

[0054] A bleaching process of cotton fabric, the specific steps of which are basically the same as those of Example 1, except that S1 is not performed, and the fabric to be treated is directly subjected to S2; the prepared pure cotton knitted fabric is dried and tested for whiteness, the CIE whiteness is 145, and the weight loss is 5.36%.

[0055] Comparative Example 4

[0056] A bleaching process of cotton fabric, the specific steps of which are basically the same as those of Example 1, except that S1 and S2 are replaced by:

[0057] S1 The main cylinder of the dyeing vat is filled with water and pure cotton knitted fabric (bath ratio is 1:8), then 0.2 g / L of scouring agent TF-129HL is added from the auxiliary cylinder, the dyeing vat continues to run, the temperature is raised to 80°C at a rate of 5°C / min, after running at 80°C for 20 min, the liquid is directly discharged, then water at 60°C is used for washing for 10 min, and S2 is performed.

[0058] S2 The bath ratio is kept at 1:8, 2 g / L of scouring agent TF-510K is added from the auxiliary cylinder, the dyeing vat continues to run, the temperature is raised to 80°C at a rate of 5°C / min, after running at 80°C for 20 min, the liquid is directly discharged, then water at 60°C is used for washing for 10 min to complete the pretreatment process;

[0059] The prepared pure cotton knitted fabric is dried and tested for whiteness, the CIE whiteness is 157, and the weight loss is 5.06%.

[0060] Example 2

[0061] A bleaching process of cotton fabric, the specific steps of which are as follows:

[0062] S1: The dyeing vat was filled with water and cotton towel (bath ratio 1:10), then 0.2 g / L of scouring agent TF-129HL and 2 g / L of de-mineralizing agent TF-510K were added from the auxiliary vat, and the mass ratio of scouring agent TF-129HL to de-mineralizing agent TF-510K was 0.1:1;

[0063] S2: The dyeing vat was continuously operated, and the temperature was raised to 80°C at a rate of 5°C / min. After 20 min of operation at 80°C, the liquid was directly discharged, then water at 60°C was used for washing for 10 min, and the liquid was discharged to complete the pretreatment process;

[0064] S3: The bath ratio was kept at 1:10, 0.4 g / L of scouring agent TF-129HL and 0.2 g / L of stabilizer TF-122F were added from the auxiliary vat, and 2.5 g / L of caustic soda was added, and after 5 min of operation, 21 g / L of hydrogen peroxide (30%) was added, and after 5 min of operation, 0.3% (o.w.f) of whitening agent CPD was added. The dyeing vat was continuously operated and the temperature was raised to 98°C at a rate of 5°C / min. After 45 min of operation at 98°C, the temperature was reduced to 80°C at a rate of 5°C / min, and the liquid was discharged;

[0065] S4: After the warm water was added, the temperature was raised to 80°C, and after 10 min of washing, the liquid was discharged. Then 60°C water was added again, and after 10 min of washing, the liquid was discharged. Finally, 30°C water was added, and after 5 min of washing, the liquid was discharged after neutralization with acetic acid, and bleached cotton fabric was obtained.

[0066] The prepared cotton towel was dried and tested for whiteness, and the CIE whiteness was 157, and the weight loss was 4.96%.

[0067] Example 3

[0068] A bleaching process for cotton fabric, the specific steps of which are basically the same as those of Example 1, except that the amount of scouring agent TF-129HL added in S1 is 0.6 g / L; and the prepared cotton knitted fabric is dried and tested for whiteness, and the CIE whiteness is 161, and the weight loss is 4.95%.

[0069] Example 4

[0070] A bleaching process for cotton fabric, the specific steps of which are basically the same as those of Example 1, except that S2 is:

[0071] S2: The dyeing vat was continuously operated, and the temperature was raised to 70°C at a rate of 7°C / min for 10 min, then the temperature was raised to 80°C at a rate of 4°C / min for 10 min, the liquid was discharged, then water at 60°C was used for washing for 10 min to complete the pretreatment process;

[0072] The prepared cotton knitted fabric was dried and tested for whiteness, and the CIE whiteness was 162, and the weight loss was 4.92%.

[0073] Example 5

[0074] A bleaching process of cotton fabric, the specific steps are as follows:

[0075] S1 After the main cylinder of the dyeing vat is filled with water and the pure cotton towel (bath ratio is 1:15), 0.2 g / L of scouring agent TF-129HL and 1 g / L of mineral removal agent TF-510K are added from the auxiliary cylinder, and the mass ratio of the scouring agent TF-129HL and the mineral removal agent TF-510K is 0.2:1;

[0076] S2 The dyeing vat continues to run, and the temperature is raised to 60°C at a rate of 5°C / min. After running at 60°C for 5 min, the liquid is directly discharged, and then the temperature is raised to 70°C at a rate of 3°C / min and kept for 15 min. The liquid is directly discharged, and then water at 60°C is used for washing for 10 min, and the liquid is discharged to complete the pretreatment process;

[0077] S3 The bath ratio is kept at 1:15, 0.2 g / L of scouring agent TF-129HL and 0.3 g / L of stabilizer TF-122F are added from the auxiliary cylinder, and then 2.5 g / L of caustic soda is added. After running for 5 min, 20 g / L of hydrogen peroxide (30%) is added, and after running for 5 min, 0.2% (o.w.f) of whitening agent CPD is added. The dyeing vat continues to run and the temperature is raised to 98°C at a rate of 5°C / min. After running at 98°C for 45 min, the temperature is reduced to 80°C at a rate of 5°C / min, and the liquid is discharged;

[0078] S4 After the warm water is added, the temperature is raised to 80°C, and after washing for 10 min, the liquid is discharged. 60°C water is added again, and after washing for 10 min, the liquid is discharged. Finally, 30°C water is added, and after washing for 5 min, the liquid is discharged after being neutralized with acetic acid, and the bleached cotton fabric is obtained.

[0079] The obtained pure cotton towel is dried and tested for whiteness, and the CIE whiteness is 153 and the weight loss is 4.97%.

[0080] Example 6

[0081] A bleaching process of cotton fabric, the specific steps are as follows:

[0082] S1 After the main cylinder of the dyeing vat is filled with water and the pure cotton towel (bath ratio is 1:15), 0.2 g / L of scouring agent TF-129HL and 1 g / L of mineral removal agent TF-510K are added from the auxiliary cylinder, and the mass ratio of the scouring agent TF-129HL and the mineral removal agent TF-510K is 0.2:1;

[0083] S2 dyeing bath continues to run, temperature is raised to 65°C at a rate of 6°C / min, after running at 65°C for 15 min, liquid is directly discharged, then temperature is raised to 75°C at a rate of 5°C / min and kept for 25 min, liquid is directly discharged, then water washing is performed at 80°C for 10 min, liquid is discharged to complete the pretreatment process;

[0084] S3 bath ratio is kept at 1:10, 0.7 g / L of scouring agent TF-129HL and 0.2 g / L of stabilizer TF-122F are added from the auxiliary cylinder, then 2.0 g / L of caustic soda is added, after running for 10 min, 15 g / L of hydrogen peroxide (30%) is added, after running for 10 min, 0.1% (o.w.f) of whitening agent CPD is added, the dyeing bath continues to run and temperature is raised to 100°C at a rate of 5°C / min, after running at 100°C for 50 min, temperature is reduced to 80°C at a rate of 5°C / min and liquid is discharged;

[0085] S4 after the warm water is added, temperature is raised to 90°C, after water washing for 10 min, liquid is discharged, then 80°C water is added again, after water washing for 10 min, liquid is discharged, finally 40°C water is added, after water washing for 5 min, liquid is discharged after acetic acid neutralization, and bleached cotton fabric is obtained.

[0086] The prepared pure cotton towel fabric is dried and tested for whiteness, CIE whiteness is 150, and weight loss is 4.20%.

[0087] Example 7

[0088] A bleaching process of cotton fabric, the specific steps are as follows:

[0089] S1 water and pure cotton towel are added to the main cylinder of the dyeing bath (bath ratio is 1:10), then 0.7 g / L of scouring agent TF-129HL and 1 g / L of mineral removal agent TF-510K are added from the auxiliary cylinder, the mass ratio of scouring agent TF-129HL to mineral removal agent TF-510K is 0.7:1;

[0090] S2 the dyeing bath continues to run, temperature is raised to 60°C at a rate of 3°C / min, after running at 60°C for 30 min, liquid is directly discharged, then water washing is performed at 70°C for 10 min, and liquid is discharged to complete the pretreatment process;

[0091] S3 bath ratio is kept at 1:10, 0.4 g / L of scouring agent TF-129HL and 0.2 g / L of stabilizer TF-122F are added from the auxiliary cylinder, then 2.5 g / L of caustic soda is added, after running for 8 min, 18 g / L of hydrogen peroxide (25%) is added, after running for 8 min, 0.3% (o.w.f) of whitening agent CPD is added, the dyeing bath continues to run and temperature is raised to 100°C at a rate of 10°C / min, after running at 100°C for 60 min, temperature is reduced to 60°C at a rate of 3°C / min and liquid is discharged;

[0092] S4: warm water is added and the temperature is raised to 80°C, water washing is performed for 10 min, then the liquid is drained, 60°C water is added again, water washing is performed for 10 min, then the liquid is drained, finally 40°C water is added, water washing is performed for 5 min, then the liquid is drained after neutralization with acetic acid, to obtain the bleached cotton fabric.

[0093] The whiteness of the prepared pure cotton towel fabric is tested after drying, and the CIE whiteness is 151 and the weight loss is 4.95%.

[0094] Example 8

[0095] A bleaching process of a cotton fabric, the specific steps are as follows:

[0096] S1: water is added to the main cylinder of the dyeing vat and pure cotton towels (bath ratio is 1:10), 0.7 g / L of scouring agent TF-129HL and 1 g / L of mineral removal agent TF-510K are added from the auxiliary cylinder, and the mass ratio of scouring agent TF-129HL and mineral removal agent TF-510K is 0.7:1;

[0097] S2: the dyeing vat continues to run, the temperature is raised to 70°C at a rate of 7°C / min, after running at 70°C for 25 min, the liquid is directly drained, then water washing is performed for 10 min with 80°C water, and the liquid is drained to complete the pretreatment process;

[0098] S3: the bath ratio is kept at 1:10, 0.4 g / L of scouring agent TF-129HL and 0.2 g / L of stabilizer TF-122F are added from the auxiliary cylinder, 2.5 g / L of caustic soda is added, running for 5 min, then 16 g / L of hydrogen peroxide (35%) is added, running for 5 min, then 0.3% (o.w.f) of whitening agent CPD is added, the dyeing vat continues to run and the temperature is raised to 98°C at a rate of 8°C / min, running at 98°C for 45 min, then the liquid is drained at a cooling rate of 5°C / min to 70°C;

[0099] S4: warm water is added and the temperature is raised to 80°C, water washing is performed for 10 min, then the liquid is drained, 60°C water is added again, water washing is performed for 10 min, then the liquid is drained, finally 40°C water is added, water washing is performed for 5 min, then the liquid is drained after neutralization with acetic acid, to obtain the bleached cotton fabric.

[0100] The whiteness of the prepared pure cotton towel fabric is tested after drying, and the CIE whiteness is 155 and the weight loss is 5%.

[0101] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high-whiteness bleaching process for cotton fabrics, characterized in that, include: A one-step bleaching and brightening bath treatment is performed on cotton fabrics pretreated with scouring agent and organic acid complexing agent under alkaline conditions at ≤100℃. The bleaching agent in the one-step bleaching and brightening bath treatment is hydrogen peroxide. The pretreatment includes: treating the cotton fabric with a hot water bath and then washing it with water after using a scouring agent and an organic acid complexing agent in a mass ratio of 0.2 to 0.7:1 to 5. The pretreatment includes: first, adding the cotton fabric to a treatment solution containing the scouring agent and organic acid complexing agent at a temperature of 20-30°C at a bath ratio of 1:8 to 1:15; then, heating the solution to 60-80°C at a rate of 3-7°C / min and holding it at that temperature for 20-30 minutes; draining the solution; and then washing the fabric with water at 60-80°C. The refining agent is TF-129HL concentrate from Transfar Group Co., Ltd., and the organic acid complexing agent is TF-510K demineralizing agent from Transfar Group Co., Ltd. The step-by-step bleaching and brightening bath treatment includes: first, adding the pretreated cotton fabric to a bleaching solution containing scouring agent, silicone-free stabilizer, and caustic soda at a bath ratio of 1:8 to 1:15, and running for 5 to 10 minutes; then, adding hydrogen peroxide solution to the bleaching solution and running for 5 to 10 minutes; next, adding brightening agent to the bleaching solution and raising the temperature to 98 to 100°C at a rate of 5 to 10°C / min and holding at that temperature for 45 to 60 minutes; then, cooling the temperature to 60 to 80°C at a rate of 3 to 5°C / min and draining the solution; and finally, washing with water.

2. The high-whiteness bleaching process for cotton fabrics as described in claim 1, characterized in that, The concentration of the organic acid complexing agent is 1–5 g / L.

3. The high-whiteness bleaching process for cotton fabrics as described in claim 1, characterized in that, The pretreatment includes: first, adding the cotton fabric to a treatment solution containing the scouring agent and organic acid complexing agent at a temperature of 20-30°C at a liquor ratio of 1:8 to 1:15; then, heating the solution to 60-70°C at a rate of 5-7°C / min and holding it at that temperature for 5-15 minutes; then, heating the solution to 70-80°C at a rate of 3-5°C / min and holding it at that temperature for 15-25 minutes; draining the solution; and then washing the fabric with water at 60-80°C.

4. The high whiteness bleaching process for cotton fabrics as described in claim 2, characterized in that, The pretreatment includes: first, adding the cotton fabric to a treatment solution containing the scouring agent and organic acid complexing agent at a temperature of 20-30°C at a liquor ratio of 1:8 to 1:15; then, heating the solution to 60-70°C at a rate of 5-7°C / min and holding it at that temperature for 5-15 minutes; then, heating the solution to 70-80°C at a rate of 3-5°C / min and holding it at that temperature for 15-25 minutes; draining the solution; and then washing the fabric with water at 60-80°C.

5. The high-whiteness bleaching process for cotton fabrics as described in claim 1, characterized in that, The specific process of water washing in the one-step bleaching and whitening bath treatment is as follows: first, a first water wash is performed at 80-90℃, then the liquid is drained and a second water wash is performed at 60-80℃, then the liquid is drained and a third water wash is performed at 30-40℃, and finally, acetic acid is added to neutralize and the liquid is drained.

6. The high whiteness bleaching process for cotton fabrics as described in claim 1, characterized in that, In the bleaching solution, the concentration of the refining agent is 0.2–0.7 g / L, the concentration of the silicone-free stabilizer is 0.2–0.4 g / L, the amount of caustic soda added is 2–2.5 g / L, the whitening agent is CPD, the amount of whitening agent added is 0.1–0.3% owf, the concentration of the hydrogen peroxide solution is 25–35%, and the amount of hydrogen peroxide solution added is 15–25 g / L.

7. The high-whiteness bleaching process for cotton fabrics as described in any one of claims 1 to 6, characterized in that, The cotton fabric is pure cotton knitted fabric or pure cotton terry cloth.

8. The high whiteness bleaching process for cotton fabrics according to claim 7, characterized in that, The cotton fabric is a pure cotton knitted fabric.

9. A cotton fabric obtained by using the high whiteness bleaching process for cotton fabrics as described in any one of claims 1 to 8.

10. Pure cotton T-shirts, pure cotton towels, or pure cotton bath towels produced using the cotton fabric as described in claim 9.

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