<section class="_135editor" data-role="paragraph" style="max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><section data-role="outer" class="article135" label="edit by 135editor" style="font-size: medium;"><section class="_135editor" data-role="paragraph" style="max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="margin-bottom: 0px; max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="font-size: 15px;">　　答 漂白、增白后的纱线放置一定时间后，一是产生黄斑，二是随时问延长白度下降。分析原因，其产生黄斑是由于漂白用水质不良，含二价铁离子较高所致，二价铁离子日久被氧化成三价铁离子，这样就在纱线上形成黄斑。这种黄斑不但影响外观质量，同时还会使纤维脆损。克服的办法是：遇水质不良时，纱线漂白前用草酸1.5～2.0g／L、在80～85℃下进行酸洗。因草酸能与铁离子生成络合离子而溶于水，水中的铁质即可去除，达到不泛黄的目的。漂白、增白纱线随时间延长而白度下降的主要原因是由于煮练不充分。若纱线煮练不充分，棉纤维中杂质未完全去除，用这种纱线立即进行漂白、增白，时问一长，纤维内部的杂质及天然色素就会显露出来造成白度下降。克服的办法是：要保证漂白纱的毛效达到13～15cm／30min，而且毛效要均匀一致，才能保证漂白、增白纱线不泛黄。另外，用次氯酸钠漂白后脱氯时，大苏打用量过多或没有洗净，亦能使纱线泛黄。纱线烘燥时，烘房温度过高、烘燥时间过长也会造成纱线泛黄。</span></p><p style="margin-bottom: 0px; max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br></p><p style="margin-bottom: 0px; max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><span style="font-size: 15px;">　　</span></p><p style="margin-bottom: 0px; max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; line-height: 1.75em; overflow-wrap: break-word !important; outline: none 0px !important;"><br></p></section><section class="_135editor" data-role="paragraph" style="max-inline-size: 100%; margin: 0px; padding: 0px; border: 0px none; z-index: 0; overflow-wrap: break-word !important; outline: none 0px !important;"><p style="margin-bottom: 0px; max-inline-size: 100%; clear: both; min-height: 1em; cursor: text; overflow-wrap: break-word !important; outline: none 0px !important;"><br></p></section><section data-role="paragraph" class="_135editor"><p><br></p></section></section></section>