Most of the fabric production requires warp sizing, which is an important process in the textile processing process and a critical processing technology. However, in the printing and dyeing process after weaving, all of the upper slurry must be removed from the fabric. Desizing waste liquid is one of the most important pollution sources in printing and dyeing factories. Its COD value is as high as 20,000~30000, which needs to be treated by special equipment and measures. According to the data analysis of some key printing and dyeing enterprises for 5 to 10 years, if the proportion of COD/BOD/SS and other indicators is taken, the desizing waste liquid accounts for more than 50% of the total pollution of printing and dyeing enterprises.
Since cotton textiles and printing and dyeing belong to the upstream and downstream industrial chain, the outstanding problems presented in the printing and dyeing process have not attracted enough attention in cotton textile enterprises. The use of green, non-polluting and environmentally friendly pulp does present a risk of increased costs. The development of environmentally friendly slurry involves the field of chemistry and even bioengineering. In our country, the first is the lack of capital investment and research strength. Second, the gap in the overall technical level is still growing.
At present, the use of slurry in domestic enterprises has poor biodegradability and may contain toxic and harmful substances. There are roughly the following types: the pulp contains carcinogenic substances, such as formaldehyde, which may cause cancer to the human body and also to the human body. The respiratory tract and skin are strongly irritated, causing respiratory inflammation and dermatitis. Some phosphate esters are also listed as carcinogens, and are mainly found in the use of phosphorus-containing auxiliaries and phosphates in sizing. Chlorine, benzene ring-containing organics, and most chlorides such as pentachlorophenol, tetrachlorophenol, 2-naphthol, and the like are present in the slurry. These chlorides are discharged into the sewage after desizing, and produce bioaccumulation after contact with the human body, which is teratogenic and carcinogenic to the human body. Harmful heavy metals are also often detected in the slurry. It is mainly introduced in the chemical raw materials used in the slurry manufacturing process, especially when the slurry is produced by using unqualified chemical test additives. For example, impurities in chemicals such as sodium hypochlorite, phosphate, urea, and the like used in the preparation of the modified starch slurry. Some heavy metal salts come into contact with the human body. Once absorbed by the body, they accumulate in the liver, bones, kidneys, heart and brain. To a certain extent, they cause great harm to health. The slurry contains difficult biodegradable substances, such as the well-known PVA, as well as some surfactants, and some acrylate pastes are also more difficult to biodegrade, which will damage the ecological environment. The slurry produces an abnormal odor. The abnormal odor is mainly caused by chemicals, which can stimulate the skin and mucous membranes, and can cause conjunctivitis and dermatitis. This is often found in acrylic pulp products.
It is worth pointing out that at present, there are not many pulps that can withstand the "ecological mark" in the domestic market, which makes it difficult for the textile industry to control pollution from the source.
The environmentally friendly slurry should have the conditions that it is harmless to the human body, environmentally friendly, and naturally degradable in the process of raw material formation, slurry production, sizing application, desizing effluent treatment and textile and clothing use. This is a whole process from production, processing to application. The green paste should pass the HJBZ30-2000 standard (the international Oko-Tex-Standard 100 standard) published by China, which sets the limit value of harmful substances on textiles. Therefore, in the future, cotton textile enterprises It is stipulated in the inspection whether the slurry contains toxic and harmful substances, and the BOD and COD and the ratio of the slurry are tested, which will become the basic conditions for the self-discipline of the industry, but the enterprises that do so at present are rare.
Of course, Chinese textile science and technology workers have used versatile copolymerized acrylic acid and high-performance modified starch sizing in pure cotton fabric sizing. Basically, PVA has not been used or used less, but this is not enough. The pollution caused by pure starch slurry. It is also very serious.
In addition to the technical and technical requirements for warp sizing, we expect the green paste to meet the following requirements: whether the raw materials for the slurry meet the requirements of ecological standards; the environmental composition does not contain the environmental label. "The undue substances listed"; when the slurry is sizing, it should not emit harmful gases and harmful volatiles; the fabric after desizing and scouring should not contain harmful or toxic substances such as formaldehyde and chlorine; The waste liquid should be highly biodegradable or easily decomposed; the energy and water consumption should be as small as possible; the pulp mill should have a quality management assurance system with an overall professional technical level.
About the author: Han Shihong, professor of Wuhan Textile University, master tutor, has deep theoretical research level and practical experience in textile sizing technology, textile slurry development and application.
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