Biaxially oriented laminated polyester film
US5656356A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 9, 1995 |
| Grant date | Aug 12, 1997 |
| Priority date | — |
| Expiry date | Jan 9, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31786
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A biaxially oriented laminated polyester film comprises a polyester substrate layer (A) and a polyester surface layer (B) containing inert particles wherein the polyester surface layer (B) has a thickness of 0.2 to 3 .mu.m with the thickness of the polyester surface layer (B) varying along the film width direction so that the surface layer (B) is thicker at the edges of the film and thinner at the center of the film. The thickness of the surface layer (B) also satisfies specified relationships based on surface layer thickness, birefringence, and orientation angle values at two different points along the film width direction in order to obtain a film whose surface layer (B) has a uniform surface roughness in the film width direction wherein the polyester surface layer (B) has a surface roughness Ra of 3 to 40 nm and a surface roughness Ra fluctuation ratio of 5% or less when measured along a distance of 500 mm in the film width direction. The laminated film can be slit and easily wound into pancake rolls.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.