While PET films, like all materials, have their challenges, such as a tendency to develop a yellow hue over time , this is often a manageable issue. This yellowing, primarily caused by exposure to ultraviolet (UV) light, aka Photo-oxidation leads to the breakdown of polymer chains and formation of chromophores. However, advancements in PET technology and treatments have significantly mitigated this effect, maintaining the clarity and performance of PET films over extended period
① PET v.s. TAC
In comparison, while Triacetyl Cellulose (TAC) is sometimes considered an alternative due to its optical properties and resistance to yellowing, it presents significant drawbacks. TAC's susceptibility to water damage, inferior barrier properties, and higher cost make it less ideal for a broad range of applications where PET excels. PET’s balance of cost-effectiveness, durability, and excellent optical performance, coupled with its improved resistance to environmental factors, positions it as the preferable choice over TAC for many optical applications.
Moreover, PET's widespread use and acceptance in recycling programs underscore its environmental advantages, further solidifying its position as the preferred material in the optical film and lens market. PET’s ability to combine performance with sustainability makes it not just a practical choice, but an environmentally responsible one.
② BioPET as a new sustainable option in the optical appplication
Since 2019, there has been a surge of interest in sustainable solutions within industrial and food packaging applications. This shift is also being observed in the realm of optical applications, where users of film-based solutions are increasingly seeking sustainable alternatives in response to new regulatory requirements, such as the EU/UK Plastic Pact.
Despite the growing demand for sustainable solutions, there's often hesitancy in the industry to move away from traditional petroleum-based PET. This is partly due to concerns about quality consistency, especially in high-precision optical applications such as TFT LCD modules, which require exceptional optical clarity. A notable concern is the yellowing of PET due to photo-oxidation over time. It's well-documented that the effects of photo-oxidation tend to be more pronounced in recycled PET facestock, which poses a significant challenge in applications demanding high precision optical quality.
However, BioPET film, composed partially of biomass-derived raw materials, emerges as a potential solution. It satisfies the market's increasing demand for sustainable products and adherence to environmental regulations, without sacrificing quality. BioPET demonstrates mechanical and optical properties on par with virgin petroleum-based PET facestock, making it a compelling alternative for optical applications that prioritize both environmental sustainability and performance.
C&T will introudct the world first BioPET Industry film with superior Optical properties in Q1 2024; and we love to prove the sneak peaks of its Mechanical properties 👇
BioPET (50μ） | Virgin-Petrol PET (50μ） | ||
BioMass base ratio | ~30% | - | |
Total Luminous Transmittance | 90 | 88 | JIS K-7361 |
Haze | 0.8 | 2.3 | JIS K-7136 |
Tensil elongation (MD) | 191% | 117% | JIS C-2318 |
Tensil elongation (TD) | 110% | 87% | JIS C-2318 |
PET films continue to be the superior option for optical applications, offering an optimal balance of Mechanical, Optical Properties, and environmental responsibility, outshining alternatives like TAC.
References:
T.Lu, E.Solis-Ramos, Y.Yi, M.Kumosa . UV degradation model for polymers and polymer matrix composites. Polymer Degradation and Stability. Retrieved August 2018. From：https://www.sciencedirect.com/science/article/abs/pii/S0141391018301964
Emad Yousif , Raghad Haddad. Photodegradation and photostabilization of polymers, especially polystyrene. 23 August 2013. From：https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4320144/ YuruWang
Yuru Wang , He Ren , Qian Zhao. Hindered phenolic antioxidants as heat-oxygen stabilizers for HDPE. 10 November 2020. From：https://doi.org/10.1177/0967391120971
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