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.
![](../../../img/products/fluo/okp/goods.jpg)
Features
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
![OKP4 Image](../../../img/products/fluo/okp/okp_okp4.jpg)
OKP4
![PMMA (methyl methacrylate resin) Image](../../../img/products/fluo/okp/okp_pmma.jpg)
PMMA (methyl methacrylate resin)
![Polycarbonate resin Image](../../../img/products/fluo/okp/okp_pc.jpg)
Polycarbonate resin
![COP (cyclo-olefin polymer) Image](../../../img/products/fluo/okp/okp_oop.jpg)
COP (cyclo-olefin polymer)
Abbe number
![Abbe number](../../img/products/fluo/okp/okp_abbe.jpg)
Physical properties
Properties | Unit,Conditions | OKP4 | OKP4HT | OKP-1 | Reference | |
---|---|---|---|---|---|---|
PC (Optical grade) |
COP | |||||
Physical properties | ||||||
Glass transition temperature | ℃ | 121 | 142 | 133 | 145 | 139 |
Heat distortion temperature | ℃,1.80MPa | 103 | 119 | 112 | 123 | 122 |
Linear expansion coefficient | ×10-5/℃ | 7.4 | 6.3 | 6.5 | 7.0 | 6.0 |
Optical properties | ||||||
Refractive index (D line) | - | 1.607 | 1.632 | 1.642 | 1.585 | 1.531 |
Abbe number | νD | 27 | 23 | 22 | 29 | 56 |
Birefringence | ×10-4,OGC method | < 5 | 55 | < 5 | 128 | 53 |
∗ 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-F Image](../../../img/products/fluo/okp/okp-f.jpg)