The disadvantage of polyamide fiber is that its optical rotation resistance is slightly poor. If it is exposed to sunlight for a long time outdoors, it is prone to yellowing and its strength decreases. Compared with polyester fiber, it has poor shape retention. Therefore, the fabric is not straight enough. Besides, its fiber surface is smooth and has a waxy feeling. In recent years, various improvement measures have been developed for these shortcomings, such as adding light resistant agents to improve optical rotation resistance, or making profiled sections to improve the appearance and luster It can be blended or interwoven with other fibers to improve the handle.