Author: Yang Honglin, item Wei, Cai regeneration The sulfinic acid produced by the reaction (H. publicly reduced, oxidized to sodium sulfate in the presence of alkali (Na0H). In 1910, Baret first synthesized sulfur dioxide veins, and it was not until 1967 that it was industrialized by Japan Tokai Electrochemical Industries Co., Ltd. As a reducing agent for low COD and BOD values, pulse is used in pulp bleaching, but it is used in dyeing and finishing bleaching process. 2.1.1 Bleaching effect It can be seen from Table 1 that in the case of primary bleaching, the sulfur dioxide pulse bleaching sample has a red-green index a, a yellow-blue index b, and a chroma. The yellowness Yl is the lowest, and the brightness L and the Hunter whiteness Wl are the highest, and the whiteness is 68. The effect of the hydrogen peroxide bleaching is close to that of the sulfur dioxide pulse, and the whiteness is 6.38, but the yellow-blue index is 6 and the chroma. Higher; the whiteness of the insurance powder bleaching sample is only 63.1. It indicates that the sulfur dioxide pulse has the strongest bleaching ability, followed by hydrogen peroxide, and the insurance powder is the weakest. In addition, it is difficult to achieve the whiteness required for production by only one bleached milk fiber. Therefore, it is necessary to carry out the re-bleaching. In the re-dispersing, hydrogen peroxide. The whiteness of the sulfur dioxide pulsed bleaching sample is the best, the red-green index a is positively negative, the chroma and yellowness are significantly lower than other bleaching methods; the hydrogen peroxide and hydrogen peroxide double bleaching method have better effects, but the yellow-blue index And chroma are higher. 2.1.2 Weight loss rate As can be seen from Table 2, the weight loss rate of reduced bleached milk fiber is smaller than that of oxidative bleaching. The single bleaching method is smaller than the complex bleaching method. In the single bleaching process, the weight loss rate of the hydrogen peroxide bleaching sample is the largest, and the sulfur dioxide pulse is the second. The minimum amount of insurance powder. In the bleaching process, there are three reasons for the weight loss of milk fiber: (1) the spinning oil on the fiber and the additive added before spinning are removed; (z) the loss of casein in the milk fiber (3) Part of the polyvinyl alcohol component was destroyed and destroyed. In addition, after testing the different breaking strength of the bleached milk fiber knitted fabric, it was found that the strength of the bleached fabric not only did not decrease, but increased to varying degrees, which may be The fabric undergoes different degrees of shrinkage during the bleaching process. 2.2 Application of sulphur dioxide sulphur in milk fiber bleaching 2.2.1 Temperature sulphur dioxide sulphide is highly temperature dependent and can only convert its unstable isomers into sulfinic acid and urea at a suitable temperature. The maximum reduction negative potential is reached. 2.2.2 pH of the bleaching liquid The sulfur dioxide pulse has a higher reduction potential only in the hot alkaline solution, while the aqueous solution of the sulfur dioxide pulse shows a certain weak acidity. The acetic acid is acidified, the sodium carbonate is adjusted to adjust the pH, and the pH is bleached. The whiteness and yellowness of the milk fiber were tested, and the results are shown in Figure 2. As can be seen from Figure 2, at 4 2.2.4 Time It can be seen from Fig. 4 that in the range of 30~60min, the time is prolonged, the whiteness of the fabric increases, and the yellowness decreases; at 6Omin, the whiteness reaches the highest and the yellowness is the lowest; >60min, the whiteness decreases obviously. It may be With the extension of time, the pH gradually decreases, which leads to the formation of colored substances during the bleaching process. Therefore, the bleaching time is determined to be 60 min. In summary, in the hydrogen peroxide--sulfur dioxide pulse bleaching method, the optimal process conditions for the bleaching of milk fiber with sulfur dioxide pulse are: sulfur dioxide pulse 2g / l, sodium carbonate to adjust the pH value 9, JFC1g / l, 80 ° C conditions Bleaching for 60 minutes, bath ratio 30:1 According to Table 3 and Table 1, it can be seen that under the condition of whiteness, the bleaching degree of the bleached fabric is significantly lower than that of other bleaching agents; when the sulfur dioxide pulse is 1.0g/L and the insurance powder is 0.5g/L, the bleaching agent is mixed. The whiteness of bleached milk fiber can reach 72.3, which is much higher than that of sulfur dioxide pulse 1g/L alone. It is close to the whiteness of 72.56 obtained by using sulfur dioxide pulse 2g/L alone, and the yellowness is the lowest. 2.5 Chemical composition and structure of bleached milk fiber In Figure 5, the characteristic absorption peaks of the crystalline and amorphous portions of the polyvinyl alcohol component appear at 1145.69Cm-1, and around 1095.74cm-1, 1654.75cm-1, and 1535.16cm, respectively. The absorption peaks of -1 are the characteristic absorption peaks of milk proteinamine 1 and guanamine n, respectively. The characteristic absorption peaks at 1017.25 cm-1 and 845.9 cm-1 are the stretching vibration peaks of methylene ether bond, 2943.35 cm- The absorption peak at 1 is the stretching vibration peak of the methylene group. As can be seen from Fig. 5, the characteristic absorption peak positions of the original sample and the bleaching sample are unchanged, and the intensity of the absorption peak is also very close. Therefore, bleaching can be considered ( Hydrogen peroxide - sulfur dioxide sulphur powder bleaching) did not change the main structure of milk fiber. From the DSC-TG analysis results in Table 5, it can be seen that the starting melting temperature and melting point of the crosslinked component polyvinyl alcohol in the bleached milk fiber are basically unchanged, but only slightly shifted toward the high temperature direction, which may be caused by a decrease in milk protein content. The maximum thermal degradation (weight loss) rate of milk fiber before and after bleaching is 306.3 °C and 298.5 °C, respectively. The absorption peak is not completely determined, and may be the composite peak of vinylon component and milk protein degradation. High Purity Refrigerant Gas R417A,Refrigerant R600,Mixed Refrigerant Beijing Starget Chemicals Co., Ltd. , http://www.bjrefrigerant.com
Key words: milk protein fiber; bleaching; hydrogen peroxide; sulfur dioxide pulse; insurance powder
The vinylon-based milk fiber formed by graft copolymerization of bovine cheese protein and polyvinyl alcohol has a deep beige color. It is difficult to achieve the desired whiteness by conventional bleaching method due to the colored components and formation of the fiber. Therefore, vinylon-based milk fiber bleaching is one of the technical problems of wet processing, and it is also a technical problem that needs to be solved in factory production.
Thiouera Dioxide is abbreviated as TD and has a molecular formula of CH4N2O2S. Pure thiourea dioxide is neither a reducing agent nor an oxidizing agent, but heating an alkaline solution containing thiourea dioxide has a high reduction potential, and the reaction formula is as follows:
1 Experiment 1.1 Materials and equipment Materials: 23s pure milk yarn jersey (rib), Heilongjiang Nenjiang Huaqiang Protein Fiber Co., Ltd. 30% H2O2 (Shanghai Jinlu Chemical Co., Ltd.) Na2C03 (Shanghai Hongguang Chemical Plant), sulfur dioxide vein ( Henan Hongye Chemical Co., Ltd., Nazsi03 (Shanghai Reagent 4), HAc (Jili Chemical Reagent Factory) and Yuanming Powder (Zhejiang Pinghu Chemical Reagent Factory) are all analytical grade, insurance powder (Shanghai Sulphuric Acid Plant Shuangliu Industry and Trade Co., Ltd.) For chemical purity, JFC, Pingping plus O (Xingtai Blue Star Auxiliary Factory), weakly acidic red 10B (Shanghai Ciba), defoamer (CibaALBATExFFC.
Equipment: Unico WFJZlo type visible spectrophotometer D, ata-Color65O computer color measurement color matching instrument, Avatar3so type Fourier transform infrared spectrometer, PL602-5 type electronic balance, TG209FI-DSC204FI type thermal analyzer, HD026N type electronic Fabric strength meter, PHSJ-4A pH meter, DcG-9070B type electric heating constant temperature blast drying box.
1.2 Bleaching process 1.2.1 Hydrogen peroxide 30% H 202 :10/gL, Na2si03 5/gL, Na2CO3 3/gL, JFC 1g/L, defoamer 0.5g/L, 70°C, 3omin, bath ratio 30:1.
1.2.2 Insurance powder Insurance powder 5 / gL, JFC 1 / gL, 80 ° C, 6omin, bath ratio 30: 1.
1.2.3 sulfur dioxide service thiourea dioxide 8g / L, JFC1g / L, pH9, 80 ° C, 60min, bath ratio 30:1.
1.3 Acid dye dyeing weak acid red 10B2% (owf), Yuanming powder 2g / l, FJC1g / l, acetic acid adjusted pH 4.5, bath ratio 50:1, 40 ° C start dyeing lomin, after heating at 80 ° C 1 ° Clmin Keep warm for 60min.
1.4 Testing 1.4.1 Whiteness and Yellowness The lab value and chroma of the sample. It was measured on a computer color measuring color meter, and the D6510 degree angle of view was used. The whiteness was evaluated by Hunter Whiteness WI and the yellowness YlASTME313-73.
Where: L is brightness, a is red and green index, b is yellow and blue index, and Y and 2 are the third of three stimulation values.
1.4.2 Weight loss rate The sample is dried in a pre-bleaching oven at 10 °C for 120 min, then rapidly cooled in a human desiccator for 30 min, quickly taken out, and weighed on an electronic balance. The Wo-bleaching method is followed by the same method to test the dry mass W1. Calculate the weight loss rate of bleaching according to formula (3).
1.4.3 Fourier transform infrared spectroscopy (FT-IR)
FT-IR is tested with an infrared light submersible (sampled by olfactory potassium).
1,4.4 Differential Thermal and Weightlessness Analysis (DSC-TG)
DSC-TG is tested by thermal analyzer (nitrogen atmosphere, gas flow rate 4omI/min, heating rate 10°C/min).
2 Results and discussion 2.1 Comparison of different bleaching methods
It can be seen from the above experiments that sulfur dioxide vein has a very good bleaching effect, and has little damage to milk fiber and no mutagenic activity. It can be considered as a non-carcinogenic substance, and is easily biodegraded, and has a low COD value. And BOD value, the decomposition products in the alkaline solution are urea and sodium sulfate, therefore, can be used as an environmentally friendly reduction bleaching agent for dyeing and finishing. Select hydrogen peroxide. Sulfur dioxide pulse bleaching method, first bleaching according to the best bleaching process of hydrogen peroxide (whiteness 66.38), and then study the complex bleaching process of sulfur dioxide pulse (measured by whiteness and yellowness).
It can be seen from Fig. 1 that as the temperature increases, the whiteness increases and the yellowness decreases; at 60-80 °C, the effect is obvious; after reaching 80 °C, the increase of whiteness slows down. It may be after 80 ° C, the decomposition of sulfur dioxide Accelerate the effective mass concentration of bleaching in a short time to reduce faster; considering the damage of high temperature to milk fiber, it is determined that the bleaching temperature is 80 °C.
2.2.3 Sulfur dioxide bismuth concentration As can be seen from Fig. 3, the sulfur dioxide pulse mass concentration increases, the whiteness of the fabric gradually increases, and the yellowness gradually decreases; the sulfur dioxide pulse has a strong reducing ability, generally only about 20% of the insurance powder Therefore, when the mass concentration of sulfur dioxide pulse is 2g/l, a good whiteness (72.56) is achieved; when the mass concentration continues to increase, the whiteness of the fabric increases slowly; when it is greater than 8g/L, the whiteness has Increased, but the increase is limited, considering the cost, choose the sulfur dioxide pulse mass concentration of 2g / l.
2.3 Sulfur dioxide service / insurance powder mixed bleach in the application of milk fiber bleaching compared with sulphur dioxide, although the pollution of the insurance powder is relatively large, the bleaching efficiency is lower, but because of its low price, it is still used in large quantities, and sulfur dioxide pulse The price is higher, and its application is greatly limited.
Weiss found that there is a good synergy between sulphur dioxide and insurance powder. In order to understand the mixed bleaching effect of sulphur dioxide and insurance powder, reduce the cost of bleaching, and at the same time reduce the environmental pollution of the powder, we discuss the sulfur dioxide pulse and Bleaching of the mixed powder of the insurance powder. Hydrogen peroxide is applied to the milk fiber. The sulfur dioxide pulsed powder mixed bleach bleaching, whiteness and yellowness of the bleaching samples are listed in Table 3.
2.4 Dyeing properties of bleached milk fiber As can be seen from Table 4, the dyeing value of the bleaching sample is 5 times lower than that of the unbleached sample. The dyeing k/s value of the bleaching sample is lower than that of the single bleaching sample. The group bound to the dye (mainly the amino group bonded to the dye anion) may be correspondingly reduced depending on the bleaching conditions, or these groups may be partially oxidized during bleaching and affect the adsorption performance of the acid dye.
3 Conclusion 3.1 The effect of bleaching milk fiber by hydrogen peroxide----sulphur dioxide pulse bleaching method is good, the whiteness reaches 72.65, and the fiber damage is small, the weight loss rate is 1.79%. The best process for reducing bleaching of sulfur dioxide pulse is: sulfur dioxide Pulse 2glL, sodium carbonate adjusted pH 9, 9, JFClg / L, 80 ° C bleaching 60min, bath ratio 30:1.
3.2 sulfur dioxide pulse 1.0g / L, insurance powder 0.5g / L mixed bleach bleaching milk fiber whiteness can reach 72.3, compared with the use of sulfur dioxide pulse alone, a large increase, close to the use of sulfur dioxide pulse 2g / L alone The obtained whiteness is 72.56, and the yellowness is the lowest.
3.3 Bleaching does not change the main structure of milk fiber, but its dyeing performance reflects that bleaching may damage polar amino acids and reduce the dyeability of weak acid dyes.
Study on the application of vinylon-based milk fiber bleaching