Search International and National Patent Collections

1. (WO1999008853) ARAMID FILM AND ITS USE, METHOD OF MANUFACTURING THE SAME, DETECTION OF PINHOLES IN THE FILM, AND DEVICE FOR THE DETECTION

Pub. No.:    WO/1999/008853    International Application No.:    PCT/JP1998/003637
Publication Date: Feb 25, 1999 International Filing Date: Aug 14, 1998
IPC: B29D 7/01
C08J 5/18
G01N 27/20
Applicants: ASAHI KASEI KOGYO KABUSHIKI KAISHA

NAGASAWA, Keisaku

KASUGA, Masahiro

TANIGUCHI, Takenori

Inventors: NAGASAWA, Keisaku

KASUGA, Masahiro

TANIGUCHI, Takenori

Title: ARAMID FILM AND ITS USE, METHOD OF MANUFACTURING THE SAME, DETECTION OF PINHOLES IN THE FILM, AND DEVICE FOR THE DETECTION
Abstract:
A thin aramid film used as a base for a magnetic tape and other products, which has an average thickness of 1-9 νm and contains at most 20 pinholes/1000 m2 detected by an electric current flowing under the following voltage applied between both sides of the film: voltage for detection (V) = 20 x (average thickness of film in νm). The film is made by the film forming process comprising casting an aramid resin solution from a die into an atmosphere with a cleanliness of JIS Class 6 or lower and wet-processing the cast aramid resin at a solvent removal rate of 3x01-5 g/sec.νm.cm2 or less to solidify the film. The obtained aramid film is inspected continuously for at least 500 m2 with an optical pinhole detector and an electric pinhole detector. The pinhole positions in the longitudinal and lateral directions can be found by calculation and output, as required.