Desizing enzyme|How to solve the smell of denim clothing

Article paragraph
1. Why does denim clothing have a residual odor?
2. What impact will the residual odor have on the wearer?
3. How to solve the residual odor


1. Why does denim clothing have a residual odor?

Consumers often find peculiar smells when buying denim clothing. There are generally two reasons for this phenomenon: one is that the odor of the black cow fabric itself is not removed in the subsequent washing process; the other is the chemical used in the washing process. The product undergoes a chemical reaction, and the generated peculiar smell remains on the clothing. Among them, the chlorine bleaching process and the high manganese treatment process are prone to produce odor.

2. What impact will the residual odor have on the wearer?

Black denim fabrics are dyed with sulfur dyes. In the dyeing process, alkali sulfide is used as a reducing agent. After dyeing, a small amount of hydrogen sulfide will remain on the fabric surface. A highly toxic substance. Inhalation of a small amount of high-concentration hydrogen sulfide can be fatal in a short time. Low-concentration hydrogen sulfide has effects on the eyes, respiratory system and central nervous system.
The residual chlorine smell after chlorine bleaching will directly affect the clothing grade, and will also cause mild poisoning of the wearer, mainly manifested as bronchitis, cough, a small amount of sputum, chest tightness, etc. Therefore, the chlorine bleaching must undergo dechlorination treatment, and the dechlorination effect directly affects the size of the residual odor of the clothing.
After high manganese rinsing, it needs to be neutralized. Sodium metabisulfite is currently the most widely used neutralizer. Sodium metabisulfite can remove manganese and neutralize only under acidic conditions. The biggest problem during use is that sulfur dioxide gas is easily released during the neutralization process, especially when phosphoric acid is added during potassium permanganate treatment. The cloth surface is very acidic. Strong, the smell becomes more prominent after contact with sodium metabisulfite. Sulfur dioxide is a colorless gas with a strong irritating odor, which can cause serious pollution to the atmosphere. It is one of the main components that cause haze and becomes the main monitoring indicator of the national air pollution control. Sulfur dioxide gas is easily dissolved in the blood and Other mucous fluids can cause inflammation of the respiratory tract, bronchitis, emphysema, and inflammation of the eye and conjunctiva. At the same time, it can also reduce the immunity of young people and weaken their ability to resist diseases.

3. How to solve the residual odor

(1) For the residual hydrogen sulfide gas in denim fabrics, suitable desizing methods can be used in the washing process of clothing to minimize the hydrogen sulfide smell. At present, the most successful desizing aids include desizing enzyme DL and hydrogen peroxide. Desizing enzyme DL does not need to adjust the pH value or add other additives when using it. When cold water is directly added to the washing machine and rotate the machine to make it uniform, then the temperature is raised to 50°C, desizing for 15-20 minutes, Desizing Enzyme DL can not only reduce the smell, but also improve the hand feel and improve the effect of subsequent cellulase washing. Desizing with hydrogen peroxide needs to control the decomposition rate of hydrogen peroxide, otherwise the desizing will be incomplete and the smell will not be removed cleanly. By using it with the oxygen bleaching stabilizer SS, it can not only control the decomposition speed of hydrogen peroxide, remove the odor, but also prevent the fading of the sewing thread used in denim clothing. Generally, desizing at 50°C for 15-20 minutes.
(2) The residual odor of chlorine bleaching is mainly caused by the insufficient reduction of the chlorine-containing components after bleaching into sodium chloride. The use of appropriate dechlorinating agents can effectively reduce the residual odor.
For the dechlorination treatment after chlorine bleaching, the common dechlorination agents on the market are sodium thiosulfate, hydrogen peroxide (hydrogen peroxide) and dechlorin DC.
Big soda has strong reducibility and can reduce the bleaching water, but after dechlorination, it is easy to leave sulfur on the fabric, causing the fabric to turn yellow. In addition, the dechlorination is not clean, and the treated clothing has a clear smell of chlorine. In addition, the baking soda itself is unstable. The sulfur dioxide produced after high-temperature heating is toxic and has a strong stimulating effect on the eyes, skin, mucous membranes and respiratory tract, and endangers the health of the operators.
Hydrogen peroxide, together with bleaching water, exhibits reducing properties, which can reduce hypochlorite in the solution to salt, thereby achieving the effect of dechlorination. However, due to the weak reducing power, the dechlorination is not clean, the residual chlorine is serious, and the chlorine smell is obvious.
Dechlorine DC is a white powder. It is mainly used to remove residual chlorine on the fabric after rinsing denim garments, replacing the sodium bicarbonate. The dosage is only 50% of the sodium bicarbonate. Thorough dechlorination, greatly reducing chlorine overflow during the dechlorination process, improving the working environment, and leaving no residual chlorine and sulfur smell on the fabric. In the washing process, the residual liquid in the washing machine does not need to be discharged after the chlorine bleaching is completed, and it can be added directly to achieve the purpose of energy saving and water saving.
(3) The odor residue after high manganese rinsing is mainly brought by the neutralizer itself. Sodium metabisulfite is cheap, and the whiteness of the neutralized cloth is good, but it will release sulfur dioxide, which is serious. Related companies began to develop and use some related alternative products, such as odorless modified sodium metabisulfite or other non-odorous chemicals, such as hydroxylamine sulfate and manganese removal crystals.
Hydroxylamine sulfate is colorless or white crystals, soluble in cold water, ethanol and methanol, and has strong reducibility. But it is expensive. Although it does not release odorous gas, the COD/BOD value in wastewater is very high.
Manganese removal crystal is a new type of neutralizer, white semi-crystalline solid, solubility in water is lower than that of hydroxylamine sulfate, and it has strong reducibility. Its price is much lower than hydroxylamine sulfate and does not release odorous gas. Compared with other neutralizers, the COD/BOD in wastewater is extremely low. After treatment, the color of denim clothing is better than sodium metabisulfite.
As long as the green chemicals are selected in the denim washing process, and the appropriate dosage and technology are used, the residual odor of the clothing can be minimized and the discomfort brought to consumers during the later wearing process can be reduced.

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