国产原创中文在线播放,亚洲无码成人在线,国产A视频日本熟女乱伦,一级在线观看视频,自不卡免费A成人欧美在线,免费在线黄片xxx综合网,亚洲欧美国产p色涩无码,黄色毛片网站A片无码在线

In recent years, domestic security protection boxes have developed rapidly. In the initial stage, they mainly supplied military and fire protection. They were mainly used in military and police. The current domestic competition is fierce, but the products themselves lack innovation and most of them imitate the safety box of the United States sent to the company. To a certain extent, there are certain patent issues, at least in the export of this piece is still very problematic.

        At present, the main materials of domestic safety protection boxes are mainly ABS plastics and modified PP engineering plastics, both of which are widely used. However, compared with the two, ABS plastics are relatively sensory, lack sufficient elasticity, and are brittle. Therefore, the protective performance is still inferior to that of modified PP engineering plastics. Modified PP engineering plastics improve the flame retardancy and strength. , impact resistance, toughness and other aspects of performance. Of course, the cost of PP material will be relatively high. The product itself does not have an absolute price advantage, but its wear-resistance, drop-resistance, and low-temperature resistance have been accepted by more people.