The selective processing technology of non-woven fabric products is becoming more and more mature

by:Sunshine     2019-11-19
The nonwoven made of cellulose fiber is not only clean in appearance and high in whiteness after cooking and bleaching, moreover, its water absorption performance, wetting performance, softness and absorption and utilization of fuel and finishing agents will change greatly. In particular, cooking and bleaching are of great significance to the production and development of non-woven sanitary materials. Cooking and bleaching are non-selective processing processes in the production process of woven products, and can be reasonably selected according to specific requirements in actual production. For example, the whiteness of non-woven fabrics that are ultimately used for medical treatment and cosmetics is not the most important performance requirement, especially for products used for fluffy pads, hemostatic plugs or wound accessories, it is more inclined to require the fiber to have the characteristics of large absorption capacity and small chemical residues. At this time, cooking and processing should be the focus, while bleaching is secondary. Bio-enzyme refining method to improve the wool effect of cloth surface cotton fiber is a natural cellulose fiber commonly used in weaving cloth. The content of natural impurities in cotton fiber depends on the origin, maturity and other factors of raw cotton. The purpose of cooking is to remove natural or artificial impurities contained in the fiber, such as wax substances and pectin substances contained in natural cotton fibers, the remaining spinning oils and oil stains on the synthetic fibers can also be removed after cooking. After cooking, the wetting and water absorption properties of non-woven fabrics can be obviously improved, the appearance quality of the products can be improved, and the interference of these impurities on dyeing and finishing can also be prevented. After cooking, the capillary effect or the percentage of wax residue can be used to test the finishing effect. Generally, the residual wax content is required to be 0. About 2%. In addition, because the fiber will be affected by chemicals while cooking and removing impurities, the degree of damage can be expressed by the degree of copper ammonia flow or by the change of non-woven fabric strength. Since the nonwoven itself is not suitable for the cooking process in the finishing of conventional fabrics after dyeing and finishing, the method of bulk fiber processing is usually used when the product needs to be cooked. When cooking, the temperature required by the process is greater than or equal to 100 ℃. If the equipment allows, it is better to use 120 ℃ ~ At 130 ℃, only this cooking condition can remove impurities in the fiber well and ensure good water absorption. Under the condition of constant dosage of boiling agent, increasing the boiling temperature is conducive to magazine removal and shortening the boiling time; On the contrary, the temperature is low and the cooking time is short. Bio-enzyme refining method is a cellulose fiber cooking and processing technology that is being vigorously promoted. In the traditional cooking process, after cooking, a large amount of clean water needs to be consumed for rinsing to produce a large amount of sewage, which has a great impact on the environment. However, the biological enzyme refining method can not only effectively remove impurities, and can greatly reduce environmental pollution. Refining with enzymes not only does not affect the skeleton of cellulose, but also can make the non-woven fabric surface (? )The damage is minimized. The proper mixing method can have a positive effect on the cooking effect. If stirred during the refining of biological enzymes, the time can be shortened and the dosage of enzymes can be reduced, while the wool effect of non-woven fabrics can also be improved. Environmentally friendly peracetic acid bleaching is put on the agenda. The purpose of bleaching is to destroy the natural and artificial pigments on non-woven fabrics and improve the whiteness of non-woven products. At present, the study on the structure and properties of natural cellulose is not yet in-depth. Through the study of brown cotton, it is found that the brown pigments in cotton fibers are mainly cypress and cotton pigments, which have the properties of acidic dyes, the molecular structure contains conjugate double bonds, and the existence of pigment will undoubtedly affect the whiteness of cotton fibers. When bleaching non-woven fabrics containing adhesives, the effect of bleach on adhesives should be considered. The bleaching of non-woven fabrics made of cotton fiber materials is better than the bleaching of semi-finished products of non-woven fabrics. Commonly used bleach also has two categories: reducibility and oxidation. Reducing bleach produces bleaching effect by reducing pigment, but after the bleached product is placed in the air for a long time, the reduced pigment has been oxidized skin color again (? )The tendency to lead to the product's Baidu persistence (? )Drop. Oxidizing bleaching agents such as sodium hypochlorite and hydrogen peroxide are commonly used in industrial non-woven fabric processing. At present, there are three bleaching methods: leaching, leaching and rolling, among which non-woven fabric bleaching is mainly leaching, while cotton staple fiber is basically in the form of loose fiber. The process flow of loose fiber bleaching belongs to intermittent processing. The processing sequence in actual production is: filling → cooking → washing → bleaching → washing → drying, or: filling → bleaching → washing → drying. Which processing sequence is adopted depends on the type of fiber to be processed. Lignin content (? ) The first processing sequence is generally adopted for cotton lint, and the second processing sequence can be adopted for combed lint with less impurity content. A British non-woven equipment manufacturer is currently developing the world's first continuous production line, which is based on a saturated leaching machine and a washing machine. Peracetic acid bleaching is a bleaching technology that has been widely studied and popularized recently. Peracetic acid is an environment-friendly bleach that has the characteristics of basically no harmful substance emission and low energy consumption during bleaching. The optimum technological conditions for bleaching peracetic acid are as follows: bleaching agent dosage 8%, temperature 70 ℃, pH value 7, bleaching time 60 min. Peracetic acid is prepared by reacting acetic anhydride or glacial acetic acid with hydrogen peroxide. Due to its easy decomposition, safety precautions must be fully considered during the manufacture, transportation and loading and unloading of Peracetic acid. The equipment materials for acetic acid bleaching are preferably stainless steel and aluminum (Minimum content 95%)Glass, ceramics, etc.
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