Compared with fluorine-containing water repellents, fabrics treated with fluorine-free water repellents usually have obvious hand scratches, low adhesion, and reduced water repellency after coating. In recent years, solving the above problems has become one of the research hotspots in the industry, and good progress has been made. Through corresponding technical solutions, fabrics treated with fluorine-free water repellents can meet the requirements of scene use. This article briefly introduces how to solve the problem of obvious hand scratches.
1,Analysis of the causes of hand scratches
- ）Hand scratches on the base fabric after fluorine-free water-repellent finishing
First, compared with fluorine-containing water-repellent, the amount of fluorine-free fat water-repellent required for processing is larger, and the film hardness after shaping is thicker, and the scratches after friction are bound to be more obvious. Fluorine-containing water-repellent contains a large number of fluorine atoms in its molecular chain, and its surface energy is extremely low, which enables it to achieve the same water-repellent effect as fluorine-free water-repellent with an extremely low dosage (0.5%-2%).
Secondly, the film of fluorine-free water-repellent is harder and more brittle than that of fluorine-containing water-repellent. When squeezed by external force, it is easy to produce creases and local base layer rupture, resulting in traces remaining on the fabric surface. Similarly, because the film layer formed by fluorine-free water-repellent is not elastic enough, it is difficult to quickly restore to its original state after the traces are produced, which makes the hand scratches continue to be visible.
Finally, during the curing process of fluorine-free water-repellent, insufficient cross-linking or poor compatibility of the cross-linking agent and fluorine-free water-repellent can also lead to the appearance of persistent and visible hand scratches. - ） Hand scratches on the base fabric after fluorine-free water-repellent finishing
After the base fabric is treated with fluorine-free water-repellent, the fiber surface is covered with a fluorine-free water-repellent coating. The fluorine-free water-repellents commonly used in daily life are mostly long-chain alkyl polymers, and most of them contain wax components, which makes it easy for yarns to slip. When the fabric is squeezed, the base fabric fibers slip, causing the fluorine-free water-repellent film layer to turn white, which forms a visual "white mark", similar to a hand scratch. - ）Bonding between base fabric and coating
After fluorine-free water-repellent finishing, the base fabric fibers are wrapped by the fluorine-free water-repellent agent, which will reduce the adhesion between the base fabric and the coating, thereby affecting the bonding fastness of the coating, causing it to degummed during use, resulting in hand scratches.
2，Solution to hand scratches
1. Start with the auxiliary agent: To improve the formula of the fluorine-free water-repellent agent, you can consider adding an elastic polyurethane modifier to improve the elasticity, flexibility and adhesion of the fluorine-free water-repellent agent. You can also use silicone water-repellent agents to enhance the rebound and anti-bending properties. You can also choose a fluorine-free water-repellent agent that has improved hand scratches from the selection of auxiliary agents.
2. Start with the process: You can use a two-stage process, first apply a thin layer to enhance adhesion; reduce the baking temperature and extend the baking time; the purpose is to avoid the hardening of the fluorine-free water-repellent agent.
3. Start with the selection of fabrics: For example, choose highly elastic nylon or polyester, etc., the purpose is to improve the wrinkle resistance of the fabric.