| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress the occurrence of a stain caused by the insoluble substance precipitated on a support. <P>SOLUTION: Cellulose acylate, an additive and a solvent are approximately sent into a mixing tank 15 in proper amounts from a hopper 13, an additive tank 12 and a solvent tank 11. The solvent is regulated in its pH by a sodium hydroxide aqueous solution so that the concentration of dope 20 becomes alkaline. After the prepared mixed liquid 17 in the mixing tank 15 is heated by a heater 22 to prepare the dope 20, the dope 20 is sent to a filter 24 to be passed through a porous filter medium having an acidic functional group on its surface. Alkaline earth metal ions containing Ca<SP>2+</SP>or Mg<SP>2+</SP>in the dope 20 are attracted to the surface of the filter medium to be captured. The alkaline earth metal ions such as Ca<SP>2+</SP>or Mg<SP>2+</SP>react with COO<SP>-</SP>in the dope 20 to form a coarse metal salt and the dope 20 is filtered by a first filter device 26 to capture the metal salt. The high purity dope 20 from which the insoluble substance is removed is used to suppress the occurrence of the stain on the surface of the support in film manufacturing equipment 35. <P>COPYRIGHT: (C)2008,JPO&INPIT |
