The application effect of liquid color-fixing alkali in cold pad-batch dyeing of reactive dyes for cotton knitted fabrics was discussed. The effect of liquid color-fixing alkali on the pH value of the solution and the K/S value of dyed fabrics was tested. The effects of dyeing factors on the fixation were analyzed. The impact of color effects. The results show that: under room temperature conditions, the mass concentration of liquid color-fixing alkali is 2 g/L, the mass concentration of Yuanming powder is 15 g/L, and the mass concentration of urea is 10 g/L. After stacking for 3 hours, the color fastness of dyed fabrics to soaping is determined. , color fastness to rubbing, strong damage and dyeing effects are significantly improved, and satisfactory practical application results can be obtained.
The reaction between reactive dyes and cellulose fibers needs to be carried out under appropriate alkaline conditions. The alkaline agent can promote the ionization of the hydroxyl groups of the cellulose fibers into cellulose anions, and the fibers and dyes interact with each other. Valence bond combination improves color fixation rate [1]. In the traditional process, soda ash has poor water solubility, and dyes are easy to salt out; while sodium hydroxide is sensitive to dyes and is too alkaline, resulting in a low dyeing rate [2-5]; secondly, research literature on alkali substitution for cellulose reactive dyes [ 6-7], which overcomes some of the shortcomings of soda ash fixation to a certain extent, but the application of cold pad liquid alkali fixation of cotton fabrics is immature and has certain research value. The development of liquid color-fixing alkali is suitable for automated continuous production of printing and dyeing. It has high dye utilization rate, good reproducibility, and has outstanding advantages in energy saving and emission reduction. It is in line with the advancement and application promotion of clean production technology during the “13th Five-Year Plan” in the printing and dyeing industry [8] .
This study aims at the effects of various alkali supply components and buffering factors on fabrics in the reactive dye dyeing process. A liquid fixing alkali with higher purity is developed and KN-type reactive dyes are screened. , applied to samples of cold pad-batch dyeing of cotton knitted fabrics, the dyeing performance of liquid fixing alkali was discussed, and the quantitative relationship of dyeing was determined, thereby facilitating the quality management of dyed products.
Test
1. Materials and instruments
Fabric: 20 tex, 180 g/m² pure Cotton knitted fabric (Zhejiang Yichuang Printing and Dyeing Co., Ltd.).
Reagents: KN type reactive series dyes (industrial grade, Shanghai Kehua Dyestuff Industrial Co., Ltd.); sodium bicarbonate, sodium carbonate, sodium hydroxide (analytically pure, Shanghai Lingfeng Chemical Reagent Co., Ltd.); Urea, Yuanming powder, soap flakes, penetrant (analytically pure, Zhejiang Chuanhua Co., Ltd.); commercially available color-fixing alkali (Dongguan Hongqi Textile Auxiliary Co., Ltd.); liquid color-fixing alkali (made in the laboratory).
Instruments: Colori7 computer color measuring and matching instrument (X-Rite Co., Ltd.); Y571B rubbing fastness meter (Laizhou Electronic Instrument Co., Ltd.); YG026D fabric strength machine (Changzhou No. 2 Textile Machinery Factory); pHS-3C precision acidimeter (Shanghai Precision Scientific Instrument Co., Ltd.); SW-12 color fastness to washing testing machine (Jiangsu Wuxi Textile Instrument Factory); HH-4 digital constant temperature water bath (Changzhou Guohua Electrical Appliances Co., Ltd.); DHG-9240A electric constant temperature blast drying oven (Shanghai Jinghong Experimental Equipment Co., Ltd.).
2. Experimental method
2.1 Liquid color-fixing alkali one-bath cold pad-batch dyeing process One-bath cold pad-batch process: cotton fabric immersion Pad dyeing solution (one dip and one padding, the padding rate is 70%) → rolling and stacking (room temperature 30 ℃, 2 to 8 hours) → washing → soaping (detergent 2 g/L, 95 ℃, 10 min) → Wash → Dry.
2.2 Fixation alkali cold pad batch reference process
Cold pad batch process flow: cotton fabric pad dyeing solution (one dip, one pad, padding solution rate 70%) → rolled and stacked (room temperature 30 ℃, 4 hours) → washed → soaped (detergent 2 g/L, 95 ℃, 10 min) → washed → dried. Among them, soda ash is 25 g/L, urea is 20 g/L, and Yuanming powder is 30 g/L; commercial fixing alkali is 4 g/L, urea is 20 g/L, Yuanming powder is 30 g/L, and the mixture is stacked at room temperature for 4 hours.
3. Test method
3.1 Test of pH value of dye liquor
The pH value is in accordance with the standard GB/T 7573-2009 “Textiles” Determination of pH value of water extract.
3.2 K/S value test of dyed fabrics
Using the computer color measurement and matching instrument Colori7 system, after measuring 5 points at different positions of each fabric sample The average value is used to characterize the apparent color depth of the fabric.
3.3 Dye fixation rate test
The dye fixation rate is determined in accordance with the standard GB/T 27592-2011 “Determination of the fixation rate of reactive dye pad dyeing” Make a determination.
3.4 Dye hydrolysis stability test
The degree of hydrolysis is characterized by measuring the change in dye fixation rate of dyed fabrics.
3.5 Color fastness test
Color fastness to rubbing is in accordance with GB/T 3920-2008 “Textiles Color Fastness Test Color Fastness to Rubbing” test.
The color fastness to soaping is tested according to GB/T 3921.3-2008 “Textiles – Color fastness test – Color fastness to washing – Test method 3”.
3.6 Bursting Strength Test
The bursting strength of fabrics was carried out in accordance with the standard GB/T 19976-2005 “Steel Ball Method for Determination of Bursting Strength of Textiles” Measure and calculate the percentage loss of bursting strength.
Strength loss/%=(F₀-Fx)/F₀×100 In the formula: F₀ is the bursting strength of untreated cotton cloth, N; Fx is the bursting strength of cotton cloth treated with alkali agent, N.
Results and discussion
1. Stability study of color-fixing alkali
1.1 The influence of liquid color-fixing alkali mass concentration on solution pH
Dissolve different amounts of soda ash, commercially available color-fixing alkali and liquid color-fixing alkali in 1 L of distilled water respectively, and prepare solutions with different mass concentrations , measured the pH value respectively, and the results are shown in Table 1.
Table 1 Effect of alkali agent and its mass concentration on pH value
As can be seen from Table 1 , the soda ash mass concentration increased from 5 g/L to 40 g/L, the pH value increased by 0.24, �Test 2.2, color matching quality score 3%, pure cotton knitted white blank bursting strength is 580 N.
As can be seen from the performance comparison of cold pad batch dyed fabrics in Table 2, the color fastness to rubbing and soaping resistance both reached level 3 or above. After the liquid alkali fixation treatment, the color fastness of the dyed fabrics was improved. Significant improvement, while having less impact on the bursting strength of cotton knitted fabrics, indicating that liquid fixing alkali can completely replace conventional alkali agents as an alkali for fixing cold pad-batch dyeing of cotton knitted fabrics with reactive dyes.
3.2 Color index
Dyeing is carried out according to the optimized liquid fixing alkali and conventional soda ash cold pad batch process, and the soda ash fixing fabric is used as a standard sample. Compare the color indicators of dyed fabrics, see Table 3.
Table 3 Color change indicators of dyed fabrics
Note: Soda ash cold rolling batch refers to 1.2.2, this dyed cloth is a standard sample; liquid fixation alkali cooling Refer to 2.2 for padding, and use this dyed cloth as a sample; the color matching mass fraction is 3%.
It can be seen from Table 3 that cold pad-batch dyeing of reactive KN dyes uses liquid fixing alkali to fix the color. It can obtain better dyeing depth to a certain extent. The color difference of the dyed fabric fluctuates less, and the color difference changes are consistent with dyeing. Require. It shows that the dyeing depth and dyeing light of the two alkali fixation samples are basically the same, so the liquid fixation alkali can achieve the effect of the conventional dyeing process.
Conclusion
The liquid color-fixing alkali has a stable pH value, a small dosage, and good buffering capacity, and is suitable for reactive dye cooling. Pad-batch dyeing; the optimized process conditions for liquid fixing alkali active cold pad-batch dyeing are: liquid fixing alkali mass concentration 2 g/L, Yuanming powder mass concentration 15 g/L, urea mass concentration 10 g/L, stacking 3 h; liquid fixation alkali cold pad-batch dyeing, the fabric strength loss is small and the color fixation effect is excellent.
References
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