Effect of sodium chloride on dyeing
| PVA 1799 (PVA BF17) |
As an electrolyte, sodium hydroxide can promote the dyeing of cotton with reactive turquoise blue. It can change the dyeing speed and dyeing rate, with a small amount of addition and a low utilization rate of dye. With a large amount of addition, it can shorten the dyeing time, but it is not easy to dye evenly, thoroughly and easily produce color flowers. Reactive turquoise blue is less sensitive to electrolytes (compared with other reactive dyes). When the content of sodium hydroxide in the dye solution is less than 30g / L, the dyeing promotion is more obvious, the content increases, and the dyeing promotion effect is weak. When the local content of sodium hydroxide reaches 250G / L, the dye will agglomerate and salting out. In actual operation, the method of pre adding sodium hydroxide and soda ash (or bicarbonate soda) can be used, that is to say, first 1-5g / L of sodium hydroxide and 0.5g-1g/l of sodium carbonate are added into the auxiliary cylinder to fully dissolve and then put into the main cylinder. After ten minutes of operation, the dye is added. This method can improve the dye uptake of reactive turquoise blue (a small amount of alkali agent will improve the conversion of Hydroxyl Anion on cellulose) and the utilization of the dye.
When dyeing dark turquoise blue, if you need to add more sodium hydroxide or sodium hydroxide, pay special attention to the phenomenon of agglomeration and salting out when the content is too high.
Effect of soda on dyeing
| PVA |
Reactive dyes react with cellulose fibers in alkaline condition, that is, fixation reaction. In factory production, sodium carbonate can be added in several times according to the color depth, so that the pH value of the dye solution rises slowly. When the pH value is greater than 10, reactive turquoise blue is very sensitive, and attention should be paid at all times during dyeing operation.
When soda ash is added, it should also be added in several times: add 10% for the first time, use the refluxing dye solution to compare the dilution with the big bath, use a certain amount of clear water for the second and the third time, first beat it into pulp, then dilute it with hot water (60-80 ℃), and then beat it from the auxiliary cylinder to the main cylinder. The amount of soda added should be determined according to the amount of dye. If the dye is too low, the dyeing is not thorough, the amount of added is too large, and the reaction is too fast, although the amount of dye is increased to a certain extent, But it is easy to produce color flower, color difference and dye agglomeration. At the same time, the hydrolysis of dye is also accelerated. It is not easy to use the pre alkali method in the color matching of turquoise blue and light yellow, because the light yellow is sensitive to alkali, fast dye and easy to appear the problem of color and flower.
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