Soda ash is a commonly used chemical in the printing and dyeing industry. However, you can tell it all, how many functions it has, here I will tell you in detail, its twelve major uses in the printing and dyeing industry!
1. Water softener
In order to avoid the formation of water-insoluble calcium during the printing and dyeing process , magnesium soap or dye precipitation, appropriate methods can be used to remove calcium, magnesium and other salts in the water. This treatment process is called water softening.
Adding soda ash to water can cause calcium ions or magnesium ions to become carbonates and precipitate, thereby achieving a softening effect.
2. Scouring agent
The colored yarn fabric is made of It is made of dyed yarn and raw yarn that has not been scoured and bleached. The ratio of the two varies with the variety. For example, plaid has a large proportion of colored yarn, while striped poplin has a much smaller proportion of colored yarn. The scouring of colored yarn fabrics cannot use the process conditions of general cotton scouring, because the striped colored yarns in the fabrics are mostly dyed with vulcanization, reduction, naftol and other dyes.
When these dyes are simmered vigorously in high-temperature, high-pressure caustic soda and strong alkali solutions, they are easy to dissolve and stain the white ground, causing serious color matching. Therefore, when scouring plaid and plaid poplin, you must not use caustic soda, but only use soda ash alone. And the scouring cannot be done under pressure, but should be done in an open cloth cooking pot under normal pressure to avoid peeling off the inlays. The color of the colored yarn pollutes the white ground.
3. Emulsified hair scouring agent
Raw wool fiber contains a lot of dust and impurities and is not suitable for textile engineering, so the raw wool is often washed before spinning. Generally, soda ash and soap are used to emulsify fat impurities on wool and remove them.
The method is to add 3 to 10 parts of soda ash and 2 to 5 parts of soap per 1,000 parts of water, stir and refine at 45°C, and finally wash with warm water.
4. Scouring agent
Wool yarn and woolen fabrics have been scouring because of the raw wool, just to remove it again It is just the lubricating oil added during spinning and stains during manufacturing, and the procedure is much simpler than refining raw wool. Usually 2 to 4% soda ash and 1 to 3% soap of fabric weight are used at a temperature of 35 to 40°C.
5. Silk training agent
Silk fiber is mainly a combination of silk fiber and sericin It is made with very few other impurities and only contains trace amounts of waxy fat. The content of sericin is about 30%, covering the outside of silk fiber. Although its chemical composition is similar to that of silk fiber, it lacks luster and is rough and hard in nature. To take advantage of the soft and shiny properties of silk, sericin should be fully removed. .
Sericin can be softened and dissolved in hot water containing soap and weak alkalinity, while silk fiber is insoluble. Taking advantage of this characteristic, there are soap silk scouring methods and soda ash Silk training method.
6. Cotton dyeing auxiliary
Soda ash is used as a direct dye cotton dyeing auxiliary, which can alleviate dyeing and softening. The effects of hard water. When dyeing cotton with sulfur dyes, in addition to adding sodium sulfide as the dye solvent, a certain amount of soda ash is often added to assist in dissolving the dye. If the effect of alkali sulfide is sufficient, there is no need to add soda ash. In addition, for vat dyes, some soda ash is often added as an auxiliary dye.
7. Color paste alkali agent
Some vat dyes such as Shilin Yanpeach Red R, Blue 3G, etc. are relatively easy to oxidize and are also very sensitive to caustic soda. Therefore, when strong alkali is used as the alkali agent for dissolving them, the printed color will often be darker and purple; in order to overcome this defect, soda ash is often used instead. caustic soda.
In addition, due to the strong hygroscopicity of caustic soda or potassium carbonate, some colored discharge printing color pastes often produce color halo in the green edge of the pattern when steaming. In order to overcome this problem, soda ash is often used instead of caustic soda or potassium carbonate. It is best to use soda ash as alkali agent for Shilin Brown RRD.
8. Cleaning agent
When post-processing general colored cloths and printed cloths, soda ash and soap are often used as a cleaning agent. lotion. Soap is the sodium or potassium salt of higher fatty acids and is a good detergent. Soap will hydrolyze in dilute solution, and the cleaning ability will reach its peak when the concentration reaches 0.16 to 0.2%.
In order to obtain sufficient decontamination ability, especially when there is a lot of dirt, its concentration should be increased to about 0.5%. In order to inhibit the hydrolysis of soap in dilute solutions (less than 0.1%), 0.1% soda ash can be added to the lotion. The amount of soda ash in thicker lotions should be reduced. Soda ash has a softening effect on hard water, thus exerting the washing effect of soap.
9. Fixing agent
When reactive dyes are dyed on cotton fibers or synthetic fibers, It is fixed by alkaline substances. Use a dilute solution of mild alkaline substances such as sodium carbonate to obtain excellent results. The dosage can be increased or decreased according to the color concentration.
For example, when ordinary reactive dyes are used for jig dyeing, about 1% soda ash (for dye liquor) is added to the dye bath as a fixing agent in the 5th to 6th passes. Generally, there are 6 passes of dyeing and 6 passes of color fixing at a temperature of 20 to 21°C.
10. Anti-whitening agent
When preparing the anti-whitening paste for Aniline black resist printing, in addition to zinc oxide powder and whitening agent, soda ash is also added About 70 to 100 g/L, it offsets the hydrochloric acid in the Aniline Black dye component so that Aniline Black cannot develop color, thus achieving the anti-whitening effect. Sodium acetate is also used as a dye-preventing agent instead of soda ash, but the anti-whitening outline is not as clear as using soda ash.
11. “Fengyin” agent
Reactive dyes contain reactive groups that can be combined with fibers to fix them. . Currently, commonly used dyes include low-temperature fixation (X type or ordinary type) and high-temperature fixation (K type or thermosetting type).
The direct printing of reactive dyes on cotton has the advantages of bright color, excellent fastness, and no fiber brittleness caused by actinic influence. However, it also has the disadvantages of being not resistant to chlorine bleaching and the so-called “wind mark”.
“Wind print” refers to the irregular light color of the printed products exposed to the air. This is mainly due to the fact that the exposed air and acid gas react with the printed fabric before the color is steamed and solidified. And the effect is to weaken the alkali agent that the dye relies on to fix the color. Therefore, the pre-press white fabric is pre-rolled with a sufficient amount of alkali (usually 20 g/L of soda ash), which not only allows the dye to basically overcome wind marks, but also significantly improves the color yield. In addition, the printed floral fabric should be wrapped with a film or cotton cover to prevent any part of the floral fabric from being exposed. After steaming, windprint defects will no longer occur.
12. Clarifying agent
Condensation turquoise blue I5G is directly printed on cotton cloth, and the white gray cloth is pre-rolled with enough alkali before printing Agent (20 g/L of soda ash), steamed after printing, significantly improves the dye coloring amount, washing fastness, and clear outline of thin strips.
But soda ash is not suitable to replace baking soda as an alkali agent in printing paste, because using 10 g/l of soda ash instead of 10 g/l of baking soda can shorten the steaming time, but the resulting color will be darker. The stability of the color paste is also poor (the color paste using baking soda can be left for 3 to 4 days, while the color paste using soda ash can only be left for 8 hours). </p
