At present, PET film market in the field of optical film applications are more and  more important  according  to  the polyester  product  industry  development  and transformation, but the attendant technical barriers appear at the same time. With the development of flat panel display, how to prevent oxidation yellowing under long term use while maintaining the optical performance, has become an important research direction. In this paper, a novel compound antioxidant was prepared and insitu incorporated in the process of polyester synthesis. The chromaticity value of the products is improved while maintaining the optical properties and the effect is more obvious while time passed by.

 Firstly, phosphors are selected as the main ingredient and the addition amount of phosphite is optimized by the transmittance-haze meter and chromaticity value measurement. However, due to the highly susceptible to hydrolysis leading to reduced activity of phosphites, different blending modifications were conducted and magnesium-aluminum  layered double hydroxides  (LDH)  was  selected as the final blend. As for the poor organic compatibility of Mg-Al layered double hydroxides, we then repared SLDH by surface modification which guarantees the dispersion in organic environments, thus ensuring the optical properties.The performances after surface modification were measured by FT-IR, XRD, aser particle size analyzer, static contact angle tester, POM and SEM and the preparation method of antioxidant using for optical polyester was finally obtained. The hydrolysis resistance of optical antioxidant was characterized by accelerated hydrolysis experiments, FT-IR, 1H NMR and p H determination. The results show that the water-resistance of this new prepared antioxidant was greatly improved which is conducive to improve its performance of storage and use.

The above modified and blended composite antioxidant was named P-SLDH and in situincorporated into optical PET materials during the polycondensation process. Light  transmittance-haze test, chroma test, intrinsic viscosity, end carboxyl, UV accelerated aging, DSC,  TG, UV-VIS, UV-VIS, rheometer and universal  tensile testing were conducted to study the optical properties, color, thermal and mechanical properties of the synthesized PET. The results show that PETs synthesized by adding of this optical antioxidant polyester products could achieve the ability to improve the color and antioxidant properties while maintaining optical properties.

Finally, the effects of different conditions on the long-term use under different conditions were simulated. The results showed that with the prolongation of the use time and the harshness of the conditions, the color improvement when adding the above antioxidant in PET was more obvious and the light transmittance can remain stable at 89.5% or more, which is more suitable for use.

Keywords:  Compound antioxidant, hydrolysis resistance, optical properties, chromaticity, polyethylene terephthalate (PET)