COC Cyclic Olefin Copolymer: Ultra-High Transparency Optical Polymer for Medical & Electronics
Published: 2026-06-10
Cyclic Olefin Copolymer (COC) is an amorphous engineering thermoplastic that uniquely combines glass-like optical clarity with near-zero birefringence, exceptionally low water absorption, and biocompatibility. Developed and dominated by Japanese...
Cyclic Olefin Copolymer (COC) is an amorphous engineering thermoplastic that uniquely combines glass-like optical clarity with near-zero birefringence, exceptionally low water absorption, and biocompatibility. Developed and dominated by Japanese chemical companies (Zeon, Mitsui Chemicals, JSR), COC is the material of choice for precision optical components, microfluidic medical devices, and high-speed electronic packaging.
Unlike polycarbonate which absorbs up to 0.35% moisture and exhibits significant birefringence, COC absorbs virtually no water (<0.01% over 24 hours) and has extremely low birefringence — critical for optical lens systems, laser printer lenses, and smartphone camera spacers. Its density of 1.02 g/cm³ makes it 20% lighter than PC, valuable in portable electronics.
Japan's Zeon Corporation produces Zeonex, the market-leading COC for precision optics. Zeonex 480R (Tg 136 °C) is the standard grade for molded optics. Mitsui Chemicals APEL targets optical disc and lens applications, while TOPAS dominates medical microfluidics and pharmaceutical packaging.
COC processes by injection molding at melt temperatures of 240-280 °C with mold temperatures of 80-120 °C. It is compatible with standard screw designs but requires thorough drying (3-4 hours at 100 °C) to prevent splay. The material's low shrinkage and excellent flow make it ideal for micro-molding of features below 100 µm — widely used in lab-on-a-chip and microtiter plates.
Technical Properties
| Density | 1.02 g/cm³ |
|---|---|
| Tensile Strength | 60 MPa |
| Melting Point | N/A (Amorphous, Tg 136 °C) |
| Shrinkage Rate | 0.4-0.6% |
| Flexural Modulus | 3.0 GPa |
| Hdt | 130 °C at 1.82 MPa |
| Light Transmission | 91% (visible spectrum) |
| Water Absorption | <0.01% (24h, 23 °C) |
Engineering Tool: Shrinkage & Cost Estimator
Calculate part weight, mold cavity dimensions accounting for shrinkage, and material cost — all locally in your browser.
Equivalents & Cross-References
| Equivalent / Alternate | Action |
|---|---|
| Zeon Zeonex 480R | |
| TOPAS 6013 | |
| Mitsui APEL | |
| JSR Arton |
Frequently Asked Questions
How does COC compare to polycarbonate for optical applications?
COC offers lower birefringence, 10× lower water absorption (<0.01% vs 0.35% for PC), and 30% lower density. PC has higher HDT (135 °C vs 130 °C for COC) and better impact resistance. For precision optics where dimensional stability and optical clarity under humidity are paramount, COC is the superior choice.
Why is COC dominant in Japanese optical electronics?
Japanese lens manufacturers (Canon, Nikon, Olympus, Sony) use COC for molded aspheric lenses in cameras, laser printers, and medical endoscopes because it eliminates birefringence that would otherwise distort images. The ultra-low water absorption prevents focal length drift in humid environments.
Can COC be sterilized for medical applications?
COC withstands gamma radiation sterilization (25-50 kGy) and ethylene oxide (EtO) sterilization. Standard autoclave at 121 °C exceeds the Tg of most COC grades. For steam-sterilizable applications, choose a high-Tg COC grade (Zeonex 690R, Tg 156 °C) or consider PSU/PPSU as alternatives.
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References & Industry Standards
- ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
- UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
- MatWeb. Material Property Data for Engineering Thermoplastics. matweb.com
- ISO 1043. Plastics — Symbols and Abbreviated Terms. iso.org