According to an article in the Korea Herald, Kolon Indutries has succeeded in developing a clear and colorless polyimide calling it CPI™ (coloreless PI). Kolon Industries, the South Korean chemical company made news last year after settling a law suit against DuPont for infringing on IP and acquiring trade secrets. Now they have announced a new polyimide material that is mostly clear (instead of the typical brown color) making it a possible substrate for flexible displays (LCD and OLED), organic photovoltaicss and also printed circuit boards. In addition the material is resistant against radiation, opening up applications in space as well.
According to the attached specification, the flexible plastic substrate has a high thermal stability and good optical properties. The mechanical properties make it good candidate for flexible substrates. With flexible display technologies being a significant discussion point in the industry this material may open up more options to the display makers. Some other properties do not impress at the first glance (CTE, thermal shrinkage and moisture resistance). However, we have to compare this to other flexible substrates and not to glass. -NH
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Property
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Kolon CPI™ Technology
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Tolerance: Temps, solvents
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Glass transition temperature
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>330 °C |
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Coefficient of thermal expansion (CTE)
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<15 ppm/°C |
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Thermal shrinkage
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<0.1% |
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Thermo-mechanical stability
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3 hours at 20 – 150 °C |
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Chemical resistance
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resistant to acids and some solvents and alkalis; coatings can enhance resistance |
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Surface properties
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Average surface roughness
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<10 nm |
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Thickness
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10 – 100 μm |
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Surface hardness
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H~3H (pencil hardness test) |
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Barrier properties
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Moisture barrier
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<1% water absorption |
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Clarity
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Optical transparency
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>88% (at 550 nm) |
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Haze
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<1% |
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Rigidity
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Dimensional stability
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0.1% at 200 °C |
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Young’s modulus at 20 °C
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3 – 6 GPa |
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Young’s modulus at 150 °C
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~2 GPa |
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Tensile strength
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130 – 250 MPa
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Mechanically flexible?
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yes 200K at R1 (folding test) |
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Electrical properties
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Surface resistance
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1.5×1016 Ω•cm |
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Dielectric properties
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2.8 – 3.1 |
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Other features
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Radiation hard?
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yes |
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Colorless?
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yes |
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Coatable?
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CPI varnish is coatable |
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Available in powder form?
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yes |
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Can be processed in organic solvents?
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yes |
