Polyvinyl alcohol film and method for producing the same
By adjusting the refractive index balance of the PVA film and controlling the cumulative stretching ratio, the problem of balancing polarization degree and stretchability in polarization film manufacturing was solved, enabling efficient production of high-quality polarization films.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KURARAY CO LTD
- Filing Date
- 2024-12-23
- Publication Date
- 2026-07-17
AI Technical Summary
Existing technologies struggle to maintain both high polarization degree and tensile strength simultaneously during the manufacture of polarizing films. In particular, the polarization degree tends to decrease when the orientation in the TD direction is increased, leading to an increase in the breakage frequency during polarizing film manufacturing.
By adjusting the balance of the refractive index Nx in the MD direction, the refractive index Ny in the TD direction, and the refractive index Nz in the thickness direction of the PVA film, Nx and (Nx-Nz)/(Nx-Ny) are kept within a specific range. An orientation adjustment process is set after the heat treatment process to control the cumulative stretch ratio within a specific range. The manufacturing process is carried out in the order of casting, drying, heat treatment, and orientation adjustment.
A PVA film that maintains high polarization degree and excellent stretchability during the fabrication of polarizing films has been achieved, making it suitable for manufacturing polarizing films and improving the efficiency of production equipment and the quality of polarizing films.