99视频国产精品-99视频精品免视3-99视频精品全部 在线-99视频精品全部国产盗摄视频-久久亚洲一级α片-久久亚洲一级毛片

The density of plastic is small, compared with the strength is high, can obtain the higher packing rate, namely "unit mass packing volume or packing area size. Most plastics have good chemical resistance, good acid resistance, alkali resistance, resistance to all kinds of organic paste agent, long-term storage, no oxidation. It is easy to form, and the forming energy consumption is lower than that of steel and other metal materials. It has good transparency and easy coloration. Plastic packaging is one of the four major materials in the packaging industry: paper and cardboard accounts for 30%, plastic accounts for 25%, metal accounts for 25%, glass accounts for 15%. The above two 25% fully explain the importance of the plastic packaging industry. Although the plastic packaging industry is now the second packaging material, in fact, not as good as paper and cardboard packaging. But the plastic packaging industry is growing at a rate of 5% a year, and one day the plastic packaging industry will overtake paper and cardboard to become the last material.