Brief introduction of the hottest fiber grade TPU

Brief introduction to fiber grade TPU technology

fiber grade polyurethane chip, namely linear polyether colloquial (ester) thermoplastic polyurethane elastomer (TPU), through drying, melting, metering, spinning, winding, oiling, balancing and other processes, namely impact speed: get melt spun spandex products. It is mainly produced by one-step process: diisocyanate, polyether (ester) glycol, chain extender, additives, etc. are directly added into the twin-screw reactor for polymerization after measurement. With the increasingly mature production of fiber grade polyurethane chip technology and the improvement of melt spinning technology, melt spinning spandex products have been comparable to dry spinning spandex products

firstly, the properties of TPU (heat resistance and hydrolytic resistance) have been improved:

Japan's Zhongfang company uses the method of adding prepolymer to the TPU melt to improve the spinning processing conditions and the mechanical properties of the finished product. The specific method is to melt the TPU chip through a screw extruder, add the prepolymer formed by the reaction of diisocyanate and polyester or polyether glycol at its outlet, and then spin it after being evenly mixed in a static mixer. On the one hand, the addition of prepolymer can reduce the melting temperature of TPU chips, so that the spinning can be carried out at a lower temperature; On the other hand, the isocyanate group in the prepolymer can form chemical cross-linking between TPU macromolecules during the fiber forming process, so as to improve the mechanical properties of the fiber. The strength of the obtained fiber can reach 1 51cn/dtex, elongation at break gb/t 2 ⑵ 001, the end of the rib part outside the fastener is 450% - 550%, and the elastic recovery rate can still be maintained at% at 190 ℃. According to past experience, this method has been widely used in melt spinning of spandex

secondly, the storage stability of this prepolymer with isocyanate group is poor, that is, the NCO group with great activity is easy to lose its activity, so it cannot play the role of chemical crosslinking. Improvement method:

use phenol, alcohol and other compounds to block the isocyanate group in the prepolymer first. At the spinning temperature, the closed prepolymer will be reactivated and play the role of chemical crosslinking. Using aromatic glycol chain extender can further improve the heat resistance of fiber grade polyurethane chips. When the chain extender is 1,4 butanediol, about 5% crosslinking agent is added. The crosslinking agent is isocyanate terminated aliphatic polyester oligomer. After chemical crosslinking, the resilience of the fiber can be significantly improved