Learn About Heat Resistant Diaper Spandex

In order to expand the application field of diaper spandex, better meet the consumption level of people's daily necessities, and solve the problem that conventional spandex products cannot meet the application requirements, it is necessary to develop more functional diaper spandex fibers with excellent performance for the application. In this paper, the necessity and preparation method of heat-resistant diaper spandex were introduced.

1. The necessity of developing heat-resistant diaper spandex

The hard segment of diaper spandex is degraded at high temperature, and the cross-linked structure is destroyed. When blending with polyester, it often needs to be dyed many times at a temperature of about 140 ° C. As a result, the elasticity of spandex products is reduced, the yarn is broken, and the performance of the product is reduced. affected. The elasticity and strength of heat-resistant diaper spandex have no obvious downward trend after being dyed many times at high temperature (above 140 ℃). Therefore, the development of high-temperature resistant diaper spandex is an important direction for spandex products.

2. Preparation method of heat-resistant diaper spandex

(1) Increase the hard segment ratio method

The heat resistance of diaper spandex can be improved in two steps of spinning dope and spinning process. In the manufacture of spinning dope, the molecular weight and hard segment ratio of the polymer are increased, so that the polymer can retain longer segments even if it degrades. In the spinning process, the air volume of the shaft and the winding method can be changed to improve the process flow. Lu Huaqin et al. increased the proportion of aromatic rings when preparing the stock solution, and the rigidity increased. At the same time, the anti-yellowing agent UDT was added, and the anti-yellowing agent degraded preferentially at high temperature to protect the urea groups on the polyurethane chain. In the process of dry spinning, the shaft temperature and the winding draft ratio are reduced, and the situation of thread breakage due to excessive tension is avoided. Mehdipour et al. synthesized a new imide-based diol chain extender and reacted with an isocyanate-terminated prepolymer. The presence of imide units in the polymer backbone increased the proportion of aromatic rings. Rigidity increased, and no obvious weight loss was found even at a high temperature of 230°C.

(2) Additive modification method

The heat resistance can also be improved by additives, such as antioxidants to improve end groups, reduce the degradation rate or directly add high temperature resistance groups such as silicones. Ln et al. used diphenylsilanediol (DSiD) as an additive to prepare a series of silicon-containing polyurethanes. The DSiD incorporated into the polymer backbone improved the thermal stability of the polyurethane and increased the elastic recovery rate compared with before modification. 20%~30%, and increased with the increase of DSiD content. Chen Long et al. prepared hydroxyl-terminated and amino-terminated first prepolymers and second prepolymers, respectively. After dissolving, adding chain extenders and terminators to obtain polyurethane solutions and spinning, obtained elongation at break as high as 480% ~540% heat-resistant diaper spandex.

With the gradual expansion of the use of diaper spandex products, conventional diaper spandex fiber products can no longer meet the increasing demands of consumers, and it is imminent to prepare heat-resistant diaper spandex and improve its performance.