The Design, Preparation And Properties Of Novel Anti-Aging Optical Diffusers For LCD Backlight Unit

Optical diffuser is one of the key components in liquid crystal display(LCD) backlight units(BLU). Its main function is to amplify the outgoing light radiation area, to amend the backlight angle, to reduce the light intensity in unit area. Thus, optical diffuser will directly determine the quality of LCD screen. In china, there is still no independent technology for producing high-quality diffuser, and core-technology of manufacturing high-quality diffuser is still monopolized by Japan, Korea, USA, and other countries. Therefore, this paper carried out the research and exploration of the preparation of the new versatile optical diffuser via designing a series of multifunctional light-diffusing hybrid microspheres, in order to look forward to preparing good anti-aging, mechanical, anti-radiation, and specific functional diffusers. The main contents and results of the study are as follows.1. Preparation of polysiloxane@Ce02-PMMA hybrid microspheres and their application in optical diffusersThis chapter describes a new approach to prepare hybrid microsphere for obtaining optical diffuser. We developed a one pot synthesis of polysiloxane@CeO2-PMMA hybrid microspheres and examined its physical and chemical properties by transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), FT-IR spectra, UV-vis spectra and diffusing abilities analysis. The synthesized particles took on core-shell microspheres, the inner layer was CeO2/PMMA, while the thickness of polysiloxane shell was about 60 nm. The particle size of whole microspheres was focus on 450～500 nm. The diffusers based on the light-diffusing agent of polysiloxane@CeO2-PMMA had high light transmittance and haze. When the amount of polysiloxane@CeO2-PMMA reached 8 wt%, the light-diffusing effect of this novel diffuser had better than conventional diffuser. In addition, when the amount of polysiloxane@CeO2-PMMA reached 4 wt%, the light-diffusing effect of this novel diffuser was similar as conventional diffuser and had a slightly higher transmittance. However, Incident angle dependence of light-diffusing effect for the diffuser was serious, and it should be improved. Since the diffuser containing CeO2 ingredient, it had good UV-shielding effect and owned an increasing UV-shielding effect with the addition of polysiloxane@CeO2-PMMA increasing. Compared to organic diffusing microspheres, the hybrid microspheres of polysiloxane@CeO2-PMMA made the film possessing improved mechanical properties and anti-aging capacities.2. Controlled synthesis of polysiloxane@Ce02@PMMA hybrid microspheres and their application in optical diffusersIn this study, hybrid nano/microspheres of polysiloxane@CeO2@PMMA were successfully synthesized by controllable one-pot process, in which CeO2 nanoparticles are stabilized in the nano/microsphere surface of PMMA using an in-situ precipitation method. The structure of polysiloxane@CeO2@PMMA has been confirmed by XRD, TEM, SEM, and other characterization. The hybrid microspheres presented a core-shell shape, and the size of CeO2 was about 15 nm. The particle size of whole microspheres was about 550 nm. Novel diffusers based on polysiloxane@CeO2@PMMA were successfully prepared by UV curing process. The diffuser possessed relatively fine transmittance, haze, mechanical properties, UV-shielding ability, anti-aging effects, and light-diffusing effects. When the amount of polysiloxane@CeO2@PMMA reached 15 wt%, the light transmission and haze of the optical diffusers obtained 88%,89% respectively, which were slightly better than conventional diffusers.3. Large-size hybrid Microspheres of (ZnO-CeO2)@polysiloxane and their application in optical diffusersWe provided an innovative idea to synthesize core-shell microspheres with nanometer metal shell through simple one-pot process, and the large-size hybrid Microspheres of (ZnO-CeO2)@polysiloxane were successfully prepared. The structure of the hybrid Microspheres had been confirmed by XRD, TEM, SEM, and other characterization. The particle size of (ZnO-Ce02)@polysiloxane focused on 6-8μm. The diffusers based on the hybrid microspheres were prepared by UV curing process. The results of lasers scattering showed the novel diffuser based on the fillers of (ZnO-CeO2)@polysiloxane microspheres possessed suitable light transmittance, good diffusion capacity, and low incident angle dependence, which were critical and necessary for excellent optical diffusers. When the concentration of (ZnO-Ce02)@polysiloxane microspheres was up to 10 wt%, the light transmission and haze of the optical diffuser obtained 88%,87% respectively, which were as good as the commercial diffuser. When the amount of (ZnO-CeO2)@polysiloxane obtained 15 wt%, the diffuser possessed superior light diffusing effect exceeding commercial diffuser and light transmittance of the diffuser was relative low. In addition, the diffuser possessed improved mechanical properties, UV-shielding ability, strong NIR absorption, anti-aging effects, etc.4. Simple hydrothermal synthesis of large-sized light-diffusing microspheres and their application in optical diffusersIn this study, y-AlOOH, y-AlOOH@polysiloxane, and ZnO@polysiloxane microspheres were successfully synthesized via high efficient and facile hydrothermal synthesis method. The structure of them had been confirmed by XRD, TEM, SEM, and other characterization. The diffusers based on hydrothermal products were prepared by UV curing process. Moreover, the size of the series microsphere mainly distributed in 5-8 μm. The novel diffuser based on y-AlOOH microspheres had excellent light-diffusing effect, but the transmittance was quite low. Novel diffuser based on the fillers of y-AlOOH@polysiloxane or ZnO@polysiloxane possessed suitable light transmittance, good diffusion capacity, and low incident angle dependence, which were critical and necessary for excellent optical diffusers. In addition, the large-sized microspheres synthesized by hydrothermal synthesis had a good dispersibility in an organic solvent.5. Preparation and application of micron ZnO-Qds@polysixoxane light-diffusing hybrid microspheresQuantum dots(Qds) hybrid microspheres are a class of materials with special properties, and thus being introduced into the preparation of optical diffuser will make optical diffuser more multifunctional. This chapter obtained ZnO-Qds@polysixoxane hybrid microspheres via in-situ precipitation of ZnO-Qds wrapped by organopolysiloxane on the surface of polysiloxane microspheres, and the microspheres was added to the resin in the UV curing forming new optical diffuser. The structure of ZnO-Qds@polysixoxane has been confirmed by XRD, TEM, SEM, EDX and other characterization. The hybrid microspheres presented a core-shell shape, the inner particle size of polysiloxane microspheres was about 5μm, while the thickness of shell layer containing ZnO-Qds was about 300nm. The optical diffusers based on the light-diffusing agent of ZnO-Qds@polysixoxane had high light transmittance and haze. When the amount of ZnO-Qds@polysixoxane reached 10 wt%, the light transmission and haze of the optical diffuser obtained 91%,88% respectively, which owned certain advantages with comparison of commercial diffuser. When the amount of ZnO-Qds@polysixoxane obtained 15 wt%, the light-diffusing effect of this novel diffuser had better than commercial diffuser obviously. Moreover, it owned larger diffusion range, more uniform, and lower incident angle dependence of light-diffusing effect. In addition, optical diffuser had a relatively good fluorescent effect, and the diffuser prepared by ZnO-Qds@polysixoxane can resist wet-heat aging and UV-aging more significantly than the prepared diffusers of previous chapters.6. Comparison study and analysis of optical diffusers containing different light-diffusing microspheresThis chapter design a low-cost convenient device of measuring light-diffusing properties, in order to examine the variation rule of optical diffuser and its influencing factors. From a variety of diffusers placed on the same level as this device testing, it can maximize elimination deviation and obtain more reliable conclusions. Compared the results of UV-shielding and infrared absorption from various optical diffusers, the UV-shielding effect of diffusers containing CeO2 component was relatively good. Particularly, diffuser containing both ZnO and CeO2 presented more preferably UV-shielding effect. Optical diffusers containing y-AlOOH component had a significantly near-infrared absorption effect. By the comparation of transmittance, haze and light-diffusing properties, optical diffusers based on (ZnO-CeO2)polysiloxane possessed better transmittance, haze and light-diffusing effect, and it can reach or exceed the level of commercial diffusers. Besides, optical diffusers based on hybrid microspheres prepared by hydrothermal method were relatively close to the level of commercial diffuser. In addition, optical diffusers based on ZnO-Qds@polysixoxane had a low dependence on incident light angle, and possessed the strongest anti-aging ablities. Compared the dispersion of light-diffusing agents, it showed that the hybrid microspheres synthesized by hydrothermal method owned optimal dispersion properties.