Endless tubular polyimide film
View Patent ↗The present invention provides a method for producing a high-quality nonconductive or semi-conductive seamless (jointless) tubular polyimide film in a simple, efficient, and economical manner, and the like. More specifically, the invention relates to an electrically non-conductive or electrically semi-conductive seamless tubular polyimide film comprising polyimide having at least two aromatic tetracarboxylic acid derivatives comprising 15 to 55 mol % of asymmetric aromatic tetracarboxylic acid component and 85 to 45 mol % of symmetric aromatic tetracarboxylic acid component and at least one aromatic diamine component, in which, as required, a specific amount of carbon black is dispersed, and relates to a method for producing the same.
1. A seamless tubular polyimide film, comprising polyimide having at least two aromatic tetracarboxylic acid components having a mixture of 15 to 55 mol % of asymmetric aromatic tetracarboxylic acid component and 85 to 45 mol % of symmetric aromatic tetracarboxylic acid component and at least one aromatic diamine component, the seamless tubular polyimide film having a yield stress (σ Y ) of at least 120 MPa and having a tensile strength to yield stress stress ratio (σ cr /σ Y ) of at least 1.10.
2. A semi-conductive seamless tubular polyimide film, wherein
carbon black is dispersed in polyimide having at least two aromatic tetracarboxylic acid components having a mixture of 15 to 55 mol % of asymmetric aromatic tetracarboxylic acid component and 85 to 45 mol % of symmetric aromatic tetracarboxylic acid component and at least one aromatic diamine component, the semi-conductive seamless tubular polyimide film having a surface resistivity of 10 3 to 10 15 Ω/sq.
3. A semi-conductive seamless tubular polyimide film according to claim 2 , wherein
a log standard deviation of surface resistivity is 0.2 or smaller,
a log standard deviation of volume resistivity is 0.2 or smaller, and
a difference between a log surface resistivity and a log volume resistivity is 0.4 or smaller.
4. A method for producing a seamless tubular polyimide film, comprising:
rotationally molding a mixed solution substantially in a monomeric state having a mixture of an aromatic tetracarboxylic acid component comprising 15 to 55 mol % of asymmetric aromatic tetracarboxylic acid and/or ester thereof and 85 to 45 mol % of symmetric aromatic tetracarboxylic acid and/or ester thereof and an approximately equimolar amount of an aromatic diamine component, to form a tubular shape, and
imidizing the tubular material by heating.
5. A method for producing a semi-conductive seamless tubular polyimide film, comprising:
mixing an aromatic tetracarboxylic acid component comprising 15 to 55 mol % of asymmetric aromatic tetracarboxylic acid and/or ester thereof and 85 to 45 mol % of symmetric aromatic tetracarboxylic acid and/or ester thereof and an approximately equimolar amount of an aromatic diamine component, to form mixed solution substantially in a monomeric state,
dispersing 1 to 35 parts by weight of carbon black in the mixed solution, per 100 parts by weight of a total amount of the aromatic tetracarboxylic acid component and the aromatic diamine component, to form a semi-conductive monomer mixed solution,
rotationally molding the semi-conductive monomer mixed solution to form a tubular shape; and
imidizing the tubular material by heating.
6. A semi-conductive seamless tubular polyimide film for use in an intermediate transfer belt in an electrophotographic system produced by a production method of claim 5 .