Reactive dyes are commonly used dyes for cotton dyeing, and their intermittent dyeing method is still the JnT method most used in cotton knitwear. Among reactive dyes, vinyl sulfone reactive dyes with single reactive groups are still used for cyan colors based on green, bright blue and black. Double reactive group dyes are a commonly used type.
In order to develop a dyeing recipe that is consistent, that is, reproducible and streamlined, each dye manufacturer recommends different color formulas for light, medium, and dark colors. Dyeers can use two or three different dye recipes from the same manufacturer to dye different colors. These dyes are not necessarily single dyes, but can be a specially prepared mixture of dyes to obtain dyed products with high exhaustion rates and good reproducibility.
As we all know, post-dyeing treatment is an important step in reactive dye dyeing to obtain the required fastness properties. According to relevant statistics, the post-processing time for dyeing cotton knitwear accounts for 30% to 35% of the entire dyeing process, including rinsing, neutralizing, washing, soaping, rinsing and color-fixing post-processing. In order to meet end-user fastness performance requirements, dyed products should be completely free of unfixed hydrolyzed dyes, but this may require additional soaping/rinsing/washing, which not only increases process time, but also increases Water consumption.
Today, due to the increasing scarcity of water resources, the process of increasing water washing treatment is actually not feasible, and this process also has the disadvantage of increasing the amount of sewage. In order to obtain the required wet fastness and optimize the use of water resources, dye fixing agents are usually used to “fix” the hydrolyzed dyes that have not been removed by washing after one or two high-temperature soapings so as not to affect the wet fastness assessment. . In addition, post-treatment with cationic dye fixing agents can prevent contamination problems caused by hydrolyzed dyes in inappropriate storage environments.
Cationic dye fixatives for reactive dyes are now considered eco-friendly products. They are not formal-based products and have different chemical properties from formal products. However, due to the formula changes of each dye fixing agent, its performance also varies. The main problem with dye fixing agents is that they cause changes in the color and luster of dyes after treatment. Although dye fixing agent suppliers promise that their products will have little impact on color, it is still difficult to predict the color and luster of dyes after fixation.
Researchers from an Indian company conducted a study on this and explored the correlation between the chemical properties of dye fixing agents and color and light changes. In this preliminary study, the researchers performed staining in two color depths, dark and medium. The dark colors include navy blue, purple sauce, and dark green, and the medium colors include gray, olive, and brown. The effects of dyeing products treated with four different chemical types of dye fixing agents on the color and light were studied.
1Test method
1.1 Fabric
Refined and bleached 100% cotton single-jersey knitted fabrics, fabrics sampled from production were washed in the laboratory and neutralized to a pH value of 6.5.
1.2 Dyes
Use SumifixHF, RemazolRR, and RemazolRGB for dyeing dark colors; use SumifixE-XF, CibacronFN, and LevailxCA for medium-color dyes. All dye samples were provided by the dye manufacturers for laboratory research testing. Although the colors dyed with different series of dyes are not completely matched in terms of color and light, the visual color depth of the dyes was kept as similar as possible in the experiment to study the impact of the dye fixing agent on the color and light.
1.3 Dyeing
Dyeing was carried out on a laboratory dye cup dyeing machine with a liquor ratio of 1:10 and according to the standard process recommended by the dye manufacturer.
1.4 Soap boiling process
After alkali fixation, rinse with running water for 5 minutes, with a padding liquid in the middle, neutralize with acetic acid to pH 6, and wash with water for 10 minutes at this pH and temperature of 95. Rinse with flowing water for 5 minutes, and soap with 2% KaliumNNS and 2% SarakolPS at a temperature of 98 for 10 minutes. When dyeing dark colors, add a soap cooker and use running water to warm the temperature
Rinse at 95 for 10 minutes and neutralize to pH 6. Use soft water with a pH value of 6.5 for rinsing and soaping, and keep the bath ratio at 1:10. Soaping efficiency has been proven by preliminary trials and ensures complete removal of hydrolyzed dyes prior to dye fixative treatment.
1.5 Dye fixing agent treatment
Four dye fixing agents were selected, the dosage was 1% (owf), the liquor ratio was 1:10, the pH value was 6, and the dye was treated at 40 for 15 minutes. The padding fluid should maintain a uniform moisture content, dry for 100°C and check the moisture content.
1.6 Color evaluation
Use a color measurement computer and CIELAB equation to evaluate the DA and DB values and compare them with unfixed dyes.
1.7 Dye fixing agent
Fixing agent 1#: SuperfixAMGNConc. Dicyandiamide formal product; fixing agent 2#: SarafixNF504 epichlorohydrin polyamine condensation polymer; fixing agent 3#: Sarafix. AP polyethylene polyamine condensation polymer; color fixing agent 4#: Sarafix. WP’s special formula, ultra-low formaldehyde, is stable under the water washing fastness test (AATCC61.3A) at a temperature of 70°C.
2Results and Discussion
The test results are shown in Tables 1 to 6.
2.1 The influence of color-fixing agent on the shading of dark green dyes
When using RemazolRR to dye dark green, the color change after treatment with fixing agent 1# is large, while the change of color fixing agent 4# is small. The four fixatives all make the color of the treated dye redder or bluer, but the degree of change is different. When using RemazolRGB for color matching, the color difference value is much smaller than RemazolRR, but the color is greener. When using SumifixHF for color matching, fixing agent 1# and the other three fixing agentsCompared with colorants, the color light changes greatly. Compared with RemazolRR and RemazolRGB, this dye has a yellowish hue, which means it lacks blue light.
2.2 The influence of color-fixing agent on the color and light of purple sauce dyes
When RemazolRR is used to color purple sauce, the color light is seriously bluish. Among them, fixing agent 1# is the most serious, fixing agents 2# and 3# are second, and fixing agent 4# is small; when RemazolRGB is used to match colors, the color difference changes. Much smaller than RemazolRR, but the color is greener. Among them, the influence of color fixing agent 1# and color fixing agent 2# on the color light
Large, while fixing agent 4# has a low impact on the color and light; when using SumifixHF for color matching, fixing agent 4# has a large impact on the color and light. Compared with ReinazolRR and RemazolRGB dyes, the color is redder and yellower, while the other three fixatives
Colorants had similar results.
2.3 The influence of color-fixing agent on the color and light of navy blue dyes
When using Remazol I/I/navy blue, fixing agent 1# has a great influence on the color light, and its color becomes bluish and green. The other three fixing agents also have similar results, but the degree of hue change is different. Fixing agents 3# and 4# make the light greenish, while fixing agent 2# makes the light bluer
When using RemazolRGB for color matching, the fixing agent 1# makes the color light greener, so the color of the dye looks a little yellow; while the effect of the fixing agent 2# on the color light of the dye is completely different from that of RR dye, and the color light is biased. Red and yellowish! The effects of color fixing agents 3# and 4# on the color light have more or less similar results.
When using SumifixHF for color matching, fixing agent 1# makes the color light bluer and greener, and fixing agent 3# makes the color light greenish, but the degree of bluishness is slight. Fixing agent 4# makes the color greener. The very difference is that Fixing Agent 2# makes the color redder! Its effect on the color is very different from the results of the other three fixing agents.
2.4 Effect of color fixing agent on the color and light of brown dyes
When using SumifixEXF dye, the fixing agent 2# makes the color light reddish and yellowish, and the color light changes greatly. Fixing agent 3# and 4# make the color light yellowish, but the DA value does not change much, while fixing agent 1# makes the color light slightly blue and green, and has different effects on the color light with the other three fixing agents. different.
When using CibacronFN dye, fixing agent 2# makes the color light reddish, while the other three fixing agents make the color light green. All dye fixing agents make the color bluer. The one with a higher DB value is fixing agent 1#, and the one with a lower DB value is fixing agent 4#.
When using LevafixCA dye, all four dye fixing agents make the color red. Among them, fixing agent 4# has a light effect on the color light, and it is the only fixing agent that makes the color light of the dye slightly yellowish.
2.5 Effect of color fixing agent on the shade of olive dye
When using SumitqxEXF dye, fixing agent 2# makes the color reddish, while the other three fixing agents make the color greenish. Except for fixing agent 1#, the other three fixing agents have little effect on the DB value. Compared with the other three fixing agents, the color of fixing agent 1# is more bluish after treatment.
For CibacronFN dye, fixing agent 2# makes the color light red, while the other three fixing agents make the color light slightly greener. Fixing agents 1#, 3# and 4# make the color yellowish, while only fixing agent 2# makes the color bluish.
When using LevafixCA dye for color matching, except for Fixing Agent 4#, the other three fixing agents all make the color light reddish, and only Fixing Agent 4# makes the color light green. Except for fixing agent 3#, the DB values of the other three fixing agents have basically remained unchanged.
2.6 Effect of color-fixing agent on the shade of gray dyes
When using SumifixEXF dye, in addition to fixing agent 2# which makes the color light shift to infrared, the other three fixing agents make the color shift to green. In addition, fixing agents 2# and 3# make the color light yellowish, while fixing agents 1#~13 make the color light bluish. The DB value of fixing agent 4# has basically no change.
When using CibacronFN dye, similar to SumitlxEXF dye, fixing agent 2# also makes the color light reddish, while the other three fixing agents make the color light green. All four fixatives here give the color a bluish tint. The DB value of fixing agent 3# changes little. For the LevafixCA series of gray color matching dyes, except for the fixing agent 4# which has basically no effect on the color light, the other three color fixing agents make the color greenish.
3Conclusion
For medium color, fixing agent 4# has a low DF value. This means that fixing agent 4# has a light effect on the color light, which is very important for colors such as olive, gray and brown. But for dark colors, this conclusion does not apply.
For the color matching of various dyes with medium colors, fixing agent 2# makes the color reddish. Through experiments, it can be concluded that for medium and dark colors, formaldehyde-free dye fixing agents are better than dicyandiamide formal products and have little impact on the color light. Based on the above research, dyers can choose appropriate dye fixing agents to adjust the final product
Shade, in order to prevent color changes caused by dyes treated with dye-fixing agents, dyeing workers can build a database of various dye prescriptions to study the effects of various types of dye-fixing agents on their color and light. .
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