Method for the production of biaxially stretched polyester film for magnetic recording media
US5427730A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 17, 1994 |
| Grant date | Jun 27, 1995 |
| Priority date | — |
| Expiry date | Nov 17, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/258
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method for the production of biaxially stretched polyester film. The method comprises the steps of: adding cubic calcium carbonate particles of calcite structure satisfying the following conditions at any stage of polyester preparation, so as to prepare polyester resin: EQU d.sub.25 /d.sub.75 <2.00 (1) EQU 0.7.ltoreq.d.sub.50 .ltoreq.1.50 (2) EQU a:b:c=1:(1.about.1.5):(1.about.1.5) (3) wherein d.sub.25, d.sub.50 and d.sub.75 are the diameters (.mu.m) of particles when the accumulated weights of the particles are on the order of 25, 50 and 75% of the total weight of the particles, respectively, and a, b, c are width, length and height of the cubic calcium carbonate particles and the shortest one among a, b and c is set a=1; and applying melt-extrusion to the polyester resin. The biaxially stretched copolyester film provided is superior in travelling capacity as well as abrasion resistance and scratch resistance, so that it is useful for magnetic recording media.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.