The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 10, 2008
Filed:
Feb. 07, 2003
Yoshihiro Mashiko, Niigata, JP;
Toshiaki Kawanishi, Niigata, JP;
Koichi Matsunaga, Niigata, JP;
Manabu Tsuzuki, Niigata, JP;
Kazumasa Matsuoto, Niigata, JP;
Koki Goto, Chiba, JP;
Hitoshi Watanabe, Chiba, JP;
Yoshihiro Mashiko, Niigata, JP;
Toshiaki Kawanishi, Niigata, JP;
Koichi Matsunaga, Niigata, JP;
Manabu Tsuzuki, Niigata, JP;
Kazumasa Matsuoto, Niigata, JP;
Koki Goto, Chiba, JP;
Hitoshi Watanabe, Chiba, JP;
Denki Kagaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
A polyvinylacetal resin powder with a low metal content, being excellent in transparency, moisture resistance and electrical insulating properties and having a large specific surface area, and a process for its production, are presented. A polyvinylacetal resin powder obtained by reacting polyvinyl alcohol and an aldehyde in the presence of an acid catalyst, which has an acetalization degree of at least 60 mol %, a specific surface area of from 1.50 to 3.50 m/g, a bulk density of from 0.12 to 0.19 g/cm, an average particle diameter of from 0.5 to 2, 5 μm and a metal content of at most 80 ppm. It is produced, for example, by feeding a reaction fluid containing polyvinyl alcohol, an aldehyde and an acid catalyst into a first reactor, to carry out an acetalization reaction, discharging the reaction fluid wherein the acetalization degree has reached from 10 to 60 mol %, and feeding the same into a second reactor to carry out a further reaction to bring the acetalization degree of polyvinylacetal to at least 65 mol %.