共混法阻燃改性Lyocell纤维的制备及其性能

Preparation and properties of flame-retardant modified Lyocell fiber by blending method

针对共混法制备阻燃Lyocell纤维生产工艺中遇到堵板、飘断丝、凝固浴中出现阻燃剂析出等问题,采用湿法研磨工艺制备了以N-甲基吗啉-N-氧化物(NMMO)水溶液为分散介质的高分散型三聚氰胺氰尿酸(MCA)分散液,并以制备的MCA分散液作为阻燃剂制备阻燃Lyocell纤维。利用激光粒度仪、光学显微镜、扫描电子显微镜、纤度仪、热重分析仪、极限氧指数仪等测试并分析了MCA分散液粒径的稳定性及pH值稳定性、MCA在纺丝原液中的分布特性、MCA分散液粒径大小和表面助剂含量对纤维可纺性、阻燃Lyocell纤维热稳定性、力学性和阻燃性能的影响。结果表明:MCA分散液粒径及pH值基本无变化;MCA在纺丝原液中的溶解程度和溶解速度在搅拌和真空条件下会明显提高;MCA分散液粒径大小和表面助剂含量对纤维的可纺性具有显著的影响,如粒经D_(90)为0.5μm(90%数量的颗粒直径小于0.5μm),表面助剂含量占阻燃剂6%时,纺丝过程中未出现堵板、纤维飘断丝以及阻燃剂在凝固浴中大量析出等问题;当MCA含量占Lyocell纤维质量40%时,纤维表现出良好的力学性能、阻燃性能及耐洗性,其断裂强度最高为2.76 cN/dtex,极限氧指数(LOI)值为33.3%,纤维经过12次机洗后,LOI值仍保持在30%以上;另外,所制备的阻燃Lyocell纤维初试分解温度与普通Lyocell纤维相比明显提高,纤维中纤维素残炭量(约24.03%)高于未改性纤维残炭量(约16.53%)。

A highly dispersed melamine cyanuric acid(MCA)dispersion with N-methylmorpholine-N-oxide(NMMO)aqueous solution as the dispersion medium was prepared using a wet grinding process to address the issues of blockage,wire breakage and flame retardant precipitation in the production process of flame retardant Lyocell fibers using the blending method.The prepared MCA dispersion was used as the flame retardant to prepare flame retardant Lyocell fibers.The stability of MCA dispersion particle size and pH stability,the distribution characteristics of MCA in the spinning solution,the effects of particle size and surface additive content of MCA dispersion on fiber spinnability,thermal stability,mechanical properties and flame retardancy of flame retardant Lyocell fibers were analyzed using laser particle size analyzer,optical microscope,scanning electron microscope,fiber size analyzer,thermogravimetric analyzer,limiting oxygen index analyzer and other equipment.The results show that the particle size and pH value of MCA dispersion have no change.The dissolution degree and dissolution rate of MCA in the spinning solution significantly increase under stirring and vacuum conditions;The particle size of MCA dispersion and the content of surface additives have a significant impact on the spinnability of fibers.For example,when the particle size D_(90)is 0.5μm(90%of the particles have a diameter less than 0.5μm),and the content of surface additives accounts for 6%of the flame retardant,there are no problems such as blocking,fiber breakage,and a large amount of flame retardant precipitation in the coagulation bath during the spinning process;When the MCA content accounts for 40%of the weight of Lyocell fibers,the fibers exhibit good mechanical properties,flame retardancy,and washing resistance.The highest mechanical strength is 2.76 cN/dtex,and the limiting oxygen index(LOI)is 33.3%.After 12 machine washes,the LOI value of the fibers remains above 30%;In addition,the initial decomposition temperature of the prepared flame retardant Lyocell fiber was significantly increased compared to ordinary Lyocell fibers,and the residual carbon content of cellulose in the fiber(about 24.03%)was higher than that of non flame retardant fibers(about 16.53%).