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[ 2018-10-11 ] Non-woven fabrics harmless dyeing and finishing process to improve many aspects of the problem to be solved?

Author : Guide Nonwoven     
The data shows that this year, the global ecological non-woven fabric production growth rate reached 21%, the output value reached 4.5 billion US dollars.  Among them, harmless dyeing and finishing as the most critical process for the production of eco-industrial textiles, its production investment reached 1 billion yuan for the first time at the end of May this year.  Jack Spark, head of product technology safety department of the American Nonwoven Industry Association, said that the rapid increase of harmless dyeing and finishing investment is enough to reflect that this is an important direction for the development of industrial textiles in the future, and also to ensure the safety of industrial textile production and use. The inevitable choice.

Different standards have caused market applications to be chaotic.

Liu Jianyong, a professor at Tianjin Polytechnic University, clearly pointed out that the general trend of harmless dyeing and finishing of ecological nonwovens is gradually becoming obvious. However, due to many technical and cognitive problems still in the process of implementation, the identification of ecological nonwovens is recognized internationally. There are two types of standards.

One is the all-ecological concept represented by “Eco-Label”. According to this standard, the fibers used in eco-nonwoven products should be uncontaminated during the growth or production process and will not pollute the environment. The raw materials used in eco-nonwoven products use renewable resources or available waste, which will not cause ecological imbalance and predatory resource development, the so-called concept of broad ecological textiles. However, because this standard is quite strict, only the United States and Japan refer to this standard.

However, although the limited ecological concept imposes a limit on the use of some products, most projects do not have clear standards and can only refer to each other's regulations and practices, which is relatively vague. The international market without uniform standards is eagerly seeking “fusion points”.  The Chinese market is more inclined to the concept of limited ecology. Liu Jianyong said that the concept of “limited ecology” is relatively extensive and not easy to grasp for the enterprise itself. This also provides some opportunities for some unscrupulous enterprises to “invade the market”. Therefore, many dyeing and finishing agents in the domestic market are currently available. There are ecological problems with additives.  Dyeing and finishing effect is not proportional to the environmental protection index.

The definition of ecological nonwoven products in its complete sense includes four aspects: renewable and reusable raw material resources; no adverse impact on the environment during production and processing; consumer safety and health during use and The environment will not be damaged; after being discarded, it can degrade under natural conditions or cause new pollution to the environment.  The goal of textile products for eco-industry is to not cause harm to human health during use, to rationally limit the harmful substances in industrial textiles and to establish corresponding quality control systems, such as the ban on some dyeing and finishing auxiliaries and green Further implementation of the concept of additives.  EU member states including Germany are discussing the ban on some auxiliaries, but so far no ban on dyeing and finishing auxiliaries has been proposed, mainly due to the molecular structure of the dyeing and finishing agents and the opacity of the compounding ingredients. Increased difficulty in disabling auxiliaries.

Domestic research and development in this area is almost zero. In the dyeing and finishing process of non-woven fabrics, most of the products are processed by flammable and explosive solvent-based additives, which not only cause great pollution to the environment, but also pose a great threat to human health and face the export. When Europe and the United States "green barriers", more and more restrictions.

Zhao Xinzhe, technical manager of Zhejiang Jiahe Non-woven Finishing Co., Ltd., who is in the first line, pointed out that different dyeing finishing agents have different effects on the surface of non-woven fabrics. At present, most domestic finishing companies adopt the physical film forming technology of printing and dyeing auxiliaries and the hot melt film forming technology. Although the film formed by the printing and dyeing auxiliary is not completely fused with the substrate, the printing and dyeing auxiliary can partially penetrate the uneven portion of the surface of the nonwoven fabric, and although it can impart durability to the printed product, it will result in the thickness of the product after coating. Increase, while making the product feel stiff, and not very environmentally friendly.

“Although most non-woven fabric manufacturers pay great attention to improving the printing and dyeing process, the dyeing and finishing effect is not consistent with the environmental protection effect. It is always a time bomb buried by the company. Only by completely eliminating environmental hazards, ecological non-woven fabrics can have development prospects. ."  The new standard of formaldehyde removal is still difficult to play.

The key to green dyeing and finishing of non-woven materials is to eliminate the harm of formaldehyde. Formaldehyde is used as a reactant to improve the durability of dyeing and finishing auxiliaries on non-woven fabrics. However, the free formaldehyde and the release of formaldehyde from dyeing and finishing auxiliaries cause excessive amounts of formaldehyde on the nonwoven fabric, so that the formaldehyde content on the fabric may exceed The specified limit value. Non-woven fabrics finished with formaldehyde as a cross-linking agent will release some of the free formaldehyde which is not cross-linked or hydrolyzed during use, causing damage to human health. Although the current regulations or standards of various countries impose strict limits on the free formaldehyde content of products, for example, the free formaldehyde content of industrial textiles that are not in direct contact with the skin cannot exceed 300 mg/kg, but the effect is still not satisfactory.

The US Nonwovens Industry Association released the latest version of the “Biomedical Nonwovens Formaldehyde Testing Standard” at the same time as the global ecological nonwoven development overview. This standard will be implemented on August 1. After the standard is implemented, the nonwoven materials used for contact with the human body will have globally uniform testing standards. "The introduction of standards can play a certain role in regulating the development of the industry, but the company's awareness is not high, and the understanding is not enough. From the beginning of implementation to the effect, this process will not be too short, it is estimated that there will be one The batch of enterprises is therefore blocked from exporting."

It is worth mentioning that a company in the country that cooperates with the International Association for Research and Testing of Eco-Textiles has announced that the company is researching a biodegradable dispersant called formaldehyde-resistant polycondensate, which is not affected by formaldehyde. The impact of the restriction, and its biodegradability is very strong, about 70% to 75% of the part can achieve biodegradation, which will have a positive impact on the ecological environment.