Polyester (OKP Optical Plastic): For injection molding, raw material of the film
OKP is a special polyester for optical use arising from coal chemistry. OKP has a high refractive index of 1.6 or more, extremely low birefringence, and high fluidity. Therefore, it is easy to obtain high performance injection-molded objects and films.
- High refractive index
- Low birefringence
- Low Abbe number
- High fluidity
Example of usage
- Various optical lens
- Various optical films
- Other optical elements
Comparison of birefringence
PMMA (methyl methacrylate resin)
COP (cyclo-olefin polymer)
|Glass transition temperature||℃||121||142||132||145||139|
|Heat distortion temperature||℃,1.80MPa||106||123||115||123||122|
|Linear expansion coefficient||×10-5/℃||7.2||6.9||7.1||7.0||6.0|
|Refractive index (D line)||-||1.607||1.632||1.642||1.585||1.531|
|Birefringence||×10-4,OGC method||＜ 5||55||＜ 5||128||53|
|Coefficient of temperature dependence of refractive index||×10-5/℃||-13||-11||-12||-12||-10|
∗ Values of other resins indicated for comparison are quoted form catalogs and published documents.
New development product
Optical films (OKP-F)
Optical film can be produced by the melt extrusion method. It's a very low birefringence, orientation birefringence does not occur mostly by stretched.
OKP particles is high refractive index polyester resin. It stabilizes to water. Particle sizes can be controlled.