染整工艺原理后整理课件.ppt

* * * THE END * 染 整 工 艺 原 理纺织物的前处理和后整理 董 永 春 教授 纺 织 学 院 天 津 工 业 大 学 * 第九章 阻燃整理 第一节 引言 纤维制品如服装、装饰织物、产业用布易于引发火灾，需要进行阻燃整理。不同的纺织品有不同的阻燃要求。 美、英国调查：近一半的火灾是由纺织品引起的，德国调查：约20%是由装饰布引起的。 阻燃产品最初是仅用于军用特品，继而用于运输工具、公共场所的装饰布和工作服，近年来发达国家在衣服、家用织物上亦要求阻燃性。 值得指出的是阻燃整理不能使纤维不燃烧，而是降低其可燃性，离开火源后能迅速停止燃烧。阻燃是相对的。 * 第二节 关于纤维燃烧的分析 燃烧过程中的三个要素：纤维、O2和热量。 * 纤维的燃烧性 以极限需氧指数（Limiting Oxygen Index LOI or OI）指样品在氮、氧混合气环境中保持烛状燃烧所需的氧气的最小体积分数。 标准：不燃性：LOI ＞35，难燃性： LOI = 26~34 可燃性 LOI = 20~26， 高燃性： LOI ＜ 20 大气中O = 21%（V），因此一般民用纤维都是可燃性纤维。 LOI：棉 17-19，涤纶 20-22 羊毛 24-26 * 影响纤维燃烧的因素 化学组成中的H含量↑，LOI↓。 组成中N含量↑，LOI↑。 组成中的阻燃元素Cl、Br、 P、S和 Sb ，阻燃性↑。 分子结构刚性好、规整；结晶度、取白度高，燃烧性↓。 炭化倾向↑，燃烧性↑。 * THEORY OF COMBUSTION When solid materials are heated, physical and chemical changes occur at specific temperatures depending on the chemical make-up of the solid. Thermoplastic polymers soften at the glass transition temperature (Tg), and subsequently melt at Tm. At some higher temperature (Tp), both thermoplastic and non-thermoplastic solids will chemically decompose (pyrolyze) into lower molecular weight fragments. Chemical changes begin at Tp and continue through the temperature at which combustion occurs (Tc). These four temperatures are very important when considering the flame resistance of fibers. * Another important factor in combustion is the Limiting Oxygen Index (LOI). This is the amount of oxygen in the fuel mix needed to support combustion. The higher the number, the more difficult it is for combustion to occur. Values for these parameters for various fibers are given in Table 22. * * For non-thermoplastic fibers, Tp and/or Tc is less than Tg and/or Tm, however for thermoplastic fibers Tp and/or Tc is greater than Tg and/or Tm. Natural fibers are not thermoplastic, therefore when they are subjected to a heat source, pyrolysis and combustion temperatures are encountered before softening or melting temperatures are reached and event