For the existing PET products, PEN has more excellent heat resistance and strength, heat resistance of 175 ℃, Toyobo is expected to take the lead in the development of 30-40μm products.
Toyobo plans to develop a liquid crystal polarizing protective film made of polyethylene naphthalate (PEN) as a raw material within a few years.
For the existing polyethylene terephthalate (PET) products, PEN has more excellent heat resistance and strength. Among them, the performance of heat resistance, PEN has reached 175 ℃, far higher than 120 ° C for PET. In addition to the above advantages, PEN products can also have a thinner thickness. Toyobo is expected to take the lead in developing products of 30-40 μm.
At this stage, Toyobo's main liquid crystal polarizing protective film product "COSMOSHINE SRF" is made of PET. This kind of material is very superior in performance and has super birefringence, which will not cause Rainbow Irregularity on the LCD screen. At present, this product is widely used in large-size LCDs such as TVs. Toyobo expects that this product will have a market share of 40% in 2021 and eventually achieve the goal of more than half of the market share.
Although this PET product is very good, but at this stage there is a very fatal problem is its thickness.
The current mainstream thickness of "COSMOSHINE SRF" is 80 μm, and the optical films such as Triacetyl Cellulose (TAC) and Cyclo olefin polymer (COP) used in small-size LCD screens such as smartphones The thickness is only 30-40 μm. For the moment when thinness is the main theme, such shortcomings are slightly fatal, and even cover up many advantages.
Therefore, Toyobo acquired Teijin's PEN polymerization and film-forming technology through acquisitions in 2019, supplemented by the same preparation process as "COSMOSHINE SRF", to develop the PEN liquid crystal polarizing protective film, and position the target The thickness of the current mainstream of small size is 30-40 μm.
However, at present, there are still many problems with PEN films, first of all because of the reduction in birefringence caused by thinning, and secondly the high price of PEN's monomer raw materials. For these two points, Toyobo plans to evaluate from the extension conditions, polymer blending or copolymerization, lamination, or compounding with PET, etc., with a view to achieving a balance between cost and functionality.
Polyethylene naphthalate (PEN) is a new polyester variety commercialized in the 1990s. Like PET, PEN can be processed into films, fibers, hollow containers and sheets. Its excellent comprehensive performance has attracted the attention of the world polyester industry.
However, since 1997, Amoco's PEN raw material dimethyl 2,6-naphthalenedicarboxylate (2,6-NDC) production facility with a capacity of 27,000 tons / year has been in operation, and its price has been too high. Although the technology is currently mature and the production capacity reaches 35,000 tons / year, it is still too expensive compared to PET.
Therefore, PEN cannot compete with PET in most areas due to cost performance issues, which greatly limits the development of PEN.
At present, there are only a few polyester-related companies in the world that produce PEN, such as Teijin Group, Toyobo, Mitsubishi Chemical, Kinebo, UniPET, M & G (acquisition of Shell's PET and PEN business), KOSA, DuPont and Kolon. In addition, there are some polyester manufacturers (such as Eastman Chemical) who have learned the PEN manufacturing and application technology and applied for a number of patents, and are poised to wait for a favorable opportunity to enter the PEN field.