Preparation Of In-situ Curled Bicomponent Spunbond Spunlace Fabric And Its Application In Microfiber Leathe

Bicomponent spunbond spunlace technology uses a high-pressure water jet to press the split bicomponent spunbond filament web to form microfibers and entangle them with each other,producing a green,high-strength,lightweight microfiber nonwoven material,which can be used in various fields such as high-grade wiping,high-grade synthetic leather base,medical hygiene and personal care products,high precision filter materials and garments,etc.However,high-pressure water jets cause excessive entanglement between the fibers which makes the material stiff and inflexible,resulting in poor tear strength and lack of elasticity,which destroys the unique textile-like style of spunlace nonwoven materials.Meanwhile,the current spunbond production technology,spunbond filament is produced through a one-step FDY high-speed spinning,the process does not have the time and space to implement in-line curling of the fibers,and the filaments in the bicomponent spunbonded filament microfiber nonwoven material are basically in a straightened state,resulting in a flat material with a less plump feel and poor compression resilience,which limits its development and application as a microfiber leather base.This paper is based on the bicomponent spunbond spunlace technology,aiming to produce hollow segmented-pie spunbond filaments that are easy to split,while achieving in-situ in-line curling of bicomponent spunbond filaments.And to develop a microfiber leather base with a rich texture and excellent resilience for the preparation of lightweight and environmentally friendly suede microfiber leather.The details of the research are as follows:Based on the principle of hollow segmented-pie bicomponent spunbond spunbond technology,the reduction of surface adsorption energy and bonding between polymers results in the formation of an easily split composite fibers.Molecular dynamics simulations have shown that reducing the regularity and crystallinity of polymer molecular chains could reduce the surface adsorption energy and binding force between polymers.After studying the spinnability of polyesters with different crystallinity,high shrinkage polyester(low crystallinity)/polyamide 6(HSPET/PA6)hollow orange petal type composite fibers with shrinkage up to 12.27% were prepared by optimizing the spinning process.HSPET/PA6 and PET/PA6 microfiber nonwovens were prepared by the spunlace technique and the effect of spunlace pressure on the properties of the nonwovens was investigated.The results show that the splitting rate of HSPET/PA6 nonwovens is 71.39% higher than that of PET/PA6 nonwovens at the same spunlace pressure,which is consistent with the results of molecular dynamics simulations,and that the splitting of fibers at a lower spunlace pressure can effectively improve the softness and tear resistance of the nonwoven.A friction-drawing device was designed based on the principle of fibers crimping.For the first time,in-situ on-line crimping of segmented-pie bicomponent spunbond filaments has been achieved.Through the process investigation,the distance between the friction-drawer and the spinneret was 90 cm,the angle of contact between the fibers and the friction roller in the friction-drawer was 30°,the crimp rate of Curl-HSPET/PA6 fibers reached 16.60% and heat shrinkage further promoted the shrinkage and crimp of the fibers.The curling of fibers resulted in the crisscrossing of fibers in the longitudinal and horizontal directions in Curl-HSPET/PA6 bicomponent spunbond nonwoven,and the nonwoven structure was relatively fluffy.The splitting rate of Curl-HSPET/PA6 nonwoven was increased by 83.86% and 25.80% compared with PET/PA6 and HSPET/PA6 nonwovens respectively,and the shrinkage rate could reach 36.61%.The compression resilience and softness of Curl-HSPET/PA6 nonwoven after heat shrinkage was significantly improved compared to HSPET/PA6 and PET/PA6 nonwovens,and the longitudinal to horizontal strength ratio is reduced to 1.39,meanwhile the tear resistance has increased significantly.Based on the prepared Curl-HSPET/PA6 microfiber nonwoven,a lightweight suede microfiber synthetic leather was prepared using waterborne polyurethane(WPU)as elastomer and the process was optimized by the response surface method.The softness of Curl-HSPET/PA6 microfiber synthetic leather was increased by 51.94% and 22.51%relative to PET/PA6 and HSPET/PA6 microfiber leather respectively.By comparing the performance with the representative suede microfiber synthetic leather in the market,the Curl-HSPET/PA6 suede leather prepared in this study has excellent softness and resilience,breathability and mechanical properties,and achieved green and clean production.This study was the first to achieve in-situ in-line crimping of bicomponent spunbond filaments,and the preparation of easily split hollow segmented-pie composite fibers,which is of great significance for improving the softness,resilience and tear resistance of bicomponent spunbond spunlace nonwoven materials,reducing the energy consumption of spunlace and expanding the application range.