Shandong Helishi Zhongjie Chemical Co., Ltd is specializing in the production of Polyimide monomer for polyimide film, polyimide resin and insulation materials. Our main products are Pyromellitic Dianhydride(PMDA) and 4,4'-Diaminodiphenyl Ether(ODA). The annual output of PMDA is 1500mt and ODA is 1000mt. Both of the two products are sold well in domestic and overseas market. Currently, our factory has applied the patent for heavy metal control in PMDA production (Patent No. is 201210398252-5). We can also customize goods according to clients’ requirement, such as on heavy metal, particle size and TGA (Thermal gravimetric analysis).