POLYVINYL ACETAL RESIN, METHOD AND APPARATUS FOR PRODUCING THE SAME, AND ADHESIVE AND CIRCUIT BOARD USING THE POLYVINYL ACETAL RESIN

摘要

PROBLEM TO BE SOLVED: To provide a polyvinyl acetal resin which is reduced in the content of chlorine.;SOLUTION: The polyvinyl acetal resin containing ≤8 ppm chlorine is provided. The polyvinyl acetal resin can be produced, for example, by a method which comprises (1) an acetalization reaction process: a process of reacting a polyvinyl alcohol to acetalize with an aldehyde in the presence of an acid catalyst at 20-50°C reaction temperature, with ≥0.3 kW/m³ agitation power per unit volume and in ≥10 minutes average retention time, (2) a primary washing process: a process of preparing a primary cake of a polyacetal resin by pre-dehydrating the reaction product of the acetalization reaction, adding ≤40°C water to bring the product to be a slurry, washing and dehydrating the same and (3) a reslurry washing process: a process of adding ≤40°C water to the primary cake to reslurry the same, washing, dehydrating and drying the same.;COPYRIGHT: (C)2008,JPO&INPIT