vinylphenol - type polymers are useful materials and are used in many fields such as photoresist , packaging material for ic , printed circuit board , lense , etc . when the polymers are used in an electronic field such as photoresist and packaging material for ic , it is desired to reduce metal concentration in the polymer in the order of ppb units . a simple and effective process for removing metals from vinylphenol - type polymers is disclosed . the process comprises passing an organic solvent solution of a vinylphenol - type polymer either through a filter containing an ion exchange material and / or a chelate - forming material and generating a zeta potential by a cationic charge modifying agent or through a filter containing an ion exchange material and / or a chelate - forming material and a filter generating a zeta potential by a cationic charge modifying agent .