Manganese polyacid catalyst, low-temperature bleaching method of cotton fabric and application

Abstract

This invention belongs to the field of fine chemical preparation, specifically relating to a manganese polyacid catalyst, a low-temperature bleaching method for cotton fabrics, and its application. The chemical formula of the manganese polyacid catalyst is [Mn(4,4-bipy)2][HPMo]. 12 O 40 The preparation method is as follows: H4PMo 12 O 40 4,4-Bipyridine and Mn(NO3)2·4H2O are added to a mixed solvent of water and DMF, and a hydrothermal reaction is carried out to obtain the manganese polyacid catalyst. The low-temperature bleaching method involves mixing the manganese polyacid catalyst, NaOH, 30wt% hydrogen peroxide, oxygen bleaching stabilizer, refining agent, and penetrant to obtain a finishing solution; the cotton fabric to be bleached is immersed in the finishing solution, and the temperature is increased to 70-80℃ at a rate of 1-2℃ / min and held for 50-70 min. This manganese polyacid catalyst achieves low-temperature bleaching of cotton fabrics by catalyzing hydrogen peroxide, and its structure is stable and recyclable.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical preparation, specifically relating to a manganese polyacid catalyst, a low-temperature bleaching method for cotton fabrics, and their applications. Background Technology

[0002] Bleaching of cotton fabrics is a crucial step in textile processing, primarily aimed at removing pigments, improving whiteness, and enhancing fabric processing properties. A common bleaching method is hydrogen peroxide bleaching. However, traditional hydrogen peroxide (H2O2) bleaching processes for cotton knitwear require high temperatures (95-100 ℃) and strong alkaline conditions. While this imparts good whiteness to the treated fabric, it results in significant strength loss and high energy consumption, failing to meet the industry's demand for energy conservation and carbon reduction.

[0003] To address the aforementioned issues, low-temperature activation bleaching or catalytic bleaching using H2O2 has become a research hotspot in this field. This process primarily involves adding hydrogen peroxide activators or catalysts to the bleaching solution to lower the decomposition activation energy of hydrogen peroxide, thereby accelerating its decomposition into specific bleaching activating substances at low temperatures, ultimately achieving the goal of low-temperature bleaching. Commonly used activators are mainly organic, including amide groups, alkanoyl groups, and N-acyllactams. For example, Chinese patent "A Method for Bleaching Fabrics Using a Hydrogen Peroxide Bleaching Accelerator" (ZL 202010730322.7) provides a method using a hydrogen peroxide bleaching accelerator. By adding a trace amount of potassium permanganate as an accelerator to a hydrogen peroxide / gelatin copper complex system, bleaching can be achieved at temperatures below 70°C. Another patent, "A Schiff Base Manganese Complex, Preparation Method and Application," provides a Schiff base manganese complex with good water solubility and catalytic activity, achieving a whiteness of 78.3% for bleached cotton fabrics at 70°C.

[0004] However, all of the aforementioned catalysts exhibit poor recyclability, making them difficult to reuse multiple times, increasing production costs and wasting resources. Therefore, developing structurally stable and recyclable catalysts is of significant practical importance. Summary of the Invention

[0005] The purpose of this invention is to provide a manganese polyacid catalyst, a low-temperature bleaching method for cotton fabrics, and its application. The manganese polyacid catalyst catalyzes hydrogen peroxide to achieve low-temperature bleaching of cotton fabrics, and has a stable structure that can be recycled.

[0006] In a first aspect, the present invention provides a manganese polyacid catalyst having the chemical formula [Mn(4,4-bipy)2][HPMo 12 O 40 ].

[0007] A second aspect of the present invention provides a method for preparing the above-mentioned manganese polyacid catalyst, comprising the following steps:

[0008] H4PMo 12 O 40 4,4-Bipyridine and Mn(NO3)2·4H2O were added to a mixed solvent of water and DMF, and the mixture was subjected to a hydrothermal reaction to obtain the manganese polyacid catalyst.

[0009] In some embodiments of the present invention, the conditions for the hydrothermal reaction are: a reaction temperature of 90-160°C and a holding time of 12-16 hours.

[0010] In some embodiments of the present invention, H4PMo 12 O 40 The ratio of 4,4-bipyridine and Mn(NO3)2·4H2O to the mixed solvent is (0.01-0.05) g : (0.01-0.05) g : (0.01-0.05) g : 6 mL.

[0011] In some embodiments of the present invention, the volume ratio of water to DMF in the mixed solvent is (4-6):1.

[0012] A third aspect of the present invention provides a method for low-temperature bleaching of cotton fabrics, comprising the following steps:

[0013] The above-mentioned manganese polyacid catalyst, 30wt% NaOH, hydrogen peroxide, oxygen bleaching stabilizer, refining agent and penetrant are mixed to obtain a finishing solution; the cotton fabric to be bleached is immersed in the finishing solution for bleaching treatment.

[0014] In some embodiments of the present invention, the finishing solution contains 1-5 g / L of manganese polyacid catalyst, 1-10 g / L of NaOH, and 3-15 g / L of 30wt% hydrogen peroxide.

[0015] In some embodiments of the present invention, the bleaching process specifically involves heating to 70-80°C at a heating rate of 1-2°C / min and holding at that temperature for 50-70 minutes.

[0016] In some embodiments of the present invention, the oxygen bleaching stabilizer is AP-13, the refining agent is DNJ-828, and the penetrant is JFC.

[0017] In some embodiments of the present invention, the concentration of oxygen bleaching stabilizer AP-13 in the finishing solution is 2-3 g / L, the concentration of refining agent DNJ-828 is 2-3 g / L, and the concentration of penetrant JFC is 2-3 g / L.

[0018] In some embodiments of the present invention, after the bleaching process is completed, the bleached cotton fabric is further subjected to hot water washing, warm water washing and cold water washing in sequence.

[0019] In a fourth aspect, the present invention provides the application of the above-described manganese polyacid catalyst or the above-described low-temperature bleaching method in the bleaching of cotton fabrics.

[0020] Compared with existing technologies, this invention prepares a novel structurally stable manganese polyacid catalyst. This catalyst is an inorganic-organic hybrid crystalline material of manganese polyacid. By introducing the transition metal manganese, it promotes the decomposition of hydrogen peroxide at low temperatures to produce highly active substances, thereby improving the whiteness of the fabric. Moreover, low-temperature bleaching has little impact on the subsequent dyeing performance of the fabric. In addition, the compound has a stable structure, can be recycled and reused, and is conducive to energy conservation. Attached Figure Description

[0021] Figure 1 The infrared spectrum of the compound;

[0022] Figure 2 The images show dyed fabrics after bleaching using traditional methods and after bleaching using low-temperature methods. Detailed Implementation

[0023] Example 1

[0024] 0.02 gH4PMo 12 O 40 0.01 g of 4,4-bipyridine, 0.01 g of Mn(NO3)2·4H2O, 5 mL of H2O, and 1 mL of LDMF were placed in a polytetrafluoroethylene container and stirred for 30 min. The mixture was then kept at 120 °C for 14 h to obtain the manganese polyacid catalyst [Mn(4,4-bipy)2][HPMo]. 12 O 40 ].

[0025] The structure of the compound [Mn(4,4-bipy)2][HPMo] was determined using X-ray single-crystal diffraction (Gemini A Ultra diffractometer). 12 O 40 The crystallographic parameters of the compounds are shown in Table 1. The bonding properties of the compounds were tested using an infrared spectrometer. Figure 1 As shown. 1000~500 cm -1 The absorption peaks in the range are mainly characteristic absorption peaks of the polyacid skeleton, at 963, 878, 814, 759, 729, and 594 cm⁻¹. -1 The peaks at the 3300-1000 cm⁻¹ can be attributed to vibrations such as Mo-O and Mo-O-Mo; while those at 3300-1000 cm⁻¹... -1 Absorption peaks in the range, such as 1631, 1574, 1441, 1373 and 1101 cm⁻¹. -1 The characteristic absorption peak at 3438 cm⁻¹ belongs to bipyridine. Additionally, at 3438 cm⁻¹...-1 It has a broad and strong absorption band, which is the absorption band of water of crystallization.

[0026] Table 1. Crystallographic parameters of the activator

[0027]

[0028] Example 2

[0029] (1) Prepare finishing solution

[0030] In the finishing solution, the concentration of manganese polyacid catalyst is 1 g / L, the concentration of NaOH is 5 g / L, the concentration of 30 wt% hydrogen peroxide is 5 g / L, the concentration of oxygen bleaching stabilizer AP-13 is 2 g / L, the concentration of refining agent DNJ-828 is 2 g / L, and the concentration of penetrant JFC is 2 g / L.

[0031] (2) Bleaching treatment

[0032] Take a 30cm×20cm (warp×weft) knitted cotton fabric, wet it with a small amount of distilled water, squeeze it dry and immerse it in the working solution with a bath ratio of 1:20, and then heat it to 75℃ at a heating rate of 1-2℃ / min and keep it at that temperature for 60min.

[0033] (3) Post-processing

[0034] The bleached cotton fabrics were washed with hot water (70℃), warm water (40℃), and cold water, and then air-dried at room temperature.

[0035] Example 3

[0036] In the finishing solution, the content of 30wt% hydrogen peroxide was changed from 5 g / L to 10 g / L, and the rest was the same as in Example 2.

[0037] Example 4

[0038] In the finishing solution, the manganese polyacid catalyst [Mn(4,4-bipy)2][HPMo 12 O 40 The content of ] was changed from 1 g / L to 2 g / L, and the rest was the same as in Example 2.

[0039] Example 5

[0040] In the finishing solution, the content of 30wt% hydrogen peroxide was changed from 5 g / L to 10 g / L, and the manganese polyacid catalyst [Mn(4,4-bipy)2][HPMo 12 O 40 The content of ] was changed from 1 g / L to 2 g / L, and the rest was the same as in Example 2.

[0041] Comparative Example 1

[0042] The finishing solution does not contain the manganese polyacid catalyst [Mn(4,4-bipy)2][HPMo]. 12 O 40 The rest is the same as in Example 2.

[0043] Comparative Example 2

[0044] The finishing solution does not contain the manganese polyacid catalyst [Mn(4,4-bipy)2][HPMo]. 12 O 40 The rest is the same as in Example 3.

[0045] Comparative Example 3

[0046] The finishing solution does not contain the manganese polyacid catalyst [Mn(4,4-bipy)2][HPMo]. 12 O 40 The bleaching process is as follows: heat to 95°C at a heating rate of 1-2°C / min and hold for 60 minutes, with the rest being the same as in Example 2.

[0047] Test Example 1: Fabric Whiteness Test

[0048] The whiteness of the fabric was tested using a WSB-3A intelligent digital whiteness meter. Whiteness values ​​were measured at three different locations on the fabric, and the average value was taken. The results are shown in Table 2.

[0049] Table 2 Whiteness of fabrics under different conditions

[0050]

[0051] After comparison, it can be found that Example 5 can achieve the same effect as the traditional high-temperature bleaching process under low-temperature conditions. Compared with Comparative Examples 1 and 2, the whiteness of the fabric in Examples 2-4 is also significantly improved under the catalysis of the catalyst, indicating the excellent catalytic effect of the catalyst. Therefore, when the whiteness index is slightly reduced, a small amount of hydrogen peroxide can be catalyzed by the catalyst to achieve the required bleaching effect, which helps to save energy.

[0052] Test Example 2:

[0053] The manganese polyacid catalyst from Example 5 was separated and reused in the bleaching process of fabrics. The results are shown in Table 3. The manganese polyacid can be separated and reused in the catalytic hydrogen peroxide bleaching process, and the effect is still good after 5 cycles.

[0054] Table 3. Whiteness values ​​of fabrics bleached using catalyst recycling

[0055]

[0056] Test Example 3:

[0057] Fabrics bleached with manganese polyacid at low temperature were dyed with three primary colors, and the results were compared with traditional methods. The specific dyeing process is as follows: Prepare 4 g / L reactive CD deep red, 4 g / L reactive NP yellow, and 4 g / L reactive turquoise blue respectively. Cut bleached fabrics to a certain size, weigh and record the mass, moisten with distilled water, squeeze dry, and set aside. Use a pipette to transfer the required amount of dye solution, add distilled water to the total volume, so that the dye concentration is 4% (owf) and the liquor ratio is 40:1. After stirring evenly, heat the solution in a water bath to 60℃, add the fabric to the dye bath, and stir. After the first 10 minutes of dyeing, use a glass rod to hold the fabric, add NaCl to make the concentration 20 g / L, stir evenly, and then put the fabric back in. After continuing to dye for 10 minutes, use a glass rod to hold the fabric, add the required amount of Na2CO3 to make the concentration 15 g / L, stir evenly, and then put the fabric back in. Raise the temperature to 90℃ and keep it at that temperature for 30 minutes. Stir occasionally during the dyeing process to keep the fabric below the surface of the dye bath. After dyeing, the fabric underwent a post-treatment washing process: cold water washing, followed by soaping (95℃, 10 min). The soaping formula was: 2 g / L soap flakes, 2 g / L Na2CO3, and a liquor ratio of 40:1. Hot water washing followed by cold water washing and drying were then performed. The dyeing properties of the fabrics under the two bleaching processes were tested using a Datacolor colorimeter, and the results are shown in Table 4. Photos of the dyed fabrics after traditional bleaching and after low-temperature bleaching are shown below. Figure 2 As shown.

[0058] Table 4. Comparison of dyeing properties of fabrics after traditional bleaching and low-temperature bleaching.

[0059]

[0060] The comparison shows that the color parameters of the dyed fabrics treated with low-temperature bleaching and traditional bleaching are very similar, with little difference in the lightness parameter L* (characterizing the brightness of the color), chromaticity parameters a* (characterizing the color shift in the red-green direction), and b* (characterizing the color shift in the yellow-blue direction). This result indicates that low-temperature bleaching does not significantly alter the brightness and hue distribution characteristics of the fabric, and its impact on subsequent dyeing processes is negligible. In the three primary color dyeing experiments, the effect of reactive yellow is slightly larger, with a color difference (∆E) of... * = (∆L 2 +∆a 2 +∆b 2 ) 1 / 2 The color difference reached 1.218, while the color difference between Reactive Red and Reactive Blue was 0.824 and 0.514, respectively. However, overall, the low-temperature bleaching process had little impact on the subsequent dyeing performance.

Claims

1. A manganese polyacid catalyst, wherein the chemical formula of the manganese polyacid catalyst is [Mn(4,4-bipy)2][HPMo 12 O 40 ].

2. A method for preparing the manganese polyacid catalyst as described in claim 1, characterized in that, Includes the following steps: H4PMo 12 O 40 4,4-Bipyridine and Mn(NO3)2·4H2O were added to a mixed solvent of water and DMF, and the mixture was subjected to a hydrothermal reaction to obtain the manganese polyacid catalyst.

3. The preparation method according to claim 2, characterized in that, The conditions for the hydrothermal reaction are: reaction temperature of 90-160℃ and holding time of 12-16h.

4. The preparation method according to claim 2, characterized in that, H4PMo 12 O 40 The ratio of 4,4-bipyridine and Mn(NO3)2·4H2O to the mixed solvent is (0.01-0.05) g : (0.01-0.05) g : (0.01-0.05) g : 6 mL.

5. The preparation method according to claim 2, characterized in that, In the mixed solvent, the volume ratio of water to DMF is (4-6):

1.

6. A method for low-temperature bleaching of cotton fabrics, characterized in that, Includes the following steps: The manganese polyacid catalyst described in claim 1, NaOH, 30wt% hydrogen peroxide, oxygen bleaching stabilizer, refining agent and penetrant are mixed to obtain a finishing solution; The cotton fabric to be bleached is immersed in the finishing solution for bleaching.

7. The low-temperature bleaching method according to claim 6, characterized in that, The finishing solution contains 1-5 g / L of manganese polyacid catalyst, 1-10 g / L of NaOH, and 3-15 g / L of 30wt% hydrogen peroxide.

8. The low-temperature bleaching method according to claim 6, characterized in that, The bleaching process specifically involves heating the temperature to 70-80℃ at a rate of 1-2℃ / min and holding it at that temperature for 50-70 minutes. The oxygen bleaching stabilizer is AP-13, the refining agent is DNJ-828, and the penetrant is JFC.

9. The low-temperature bleaching method according to claim 6, characterized in that, After the bleaching process is completed, the process also includes washing the bleached cotton fabric in hot water, warm water, and cold water in sequence.

10. The application of the manganese polyacid catalyst as described in claim 1 or the low-temperature bleaching method as described in any one of claims 4-9 in the bleaching of cotton fabrics.

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