Characterization of UV Curable Resins and their Effects on the Performance of Brightness Enhancement Films

• Main Authors: Chang-Yi Chen, 陳昌億
• Other Authors: Kuen-Song Lin
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/20914842076901224172

碩士 === 元智大學 === 化學工程與材料科學學系 === 98 === The objectives of this study are to investigate the influence of UV resin formula, refractive index (RI) of UV resins, and process conditions on the brightness or warping of BEF product. In addition, by means of luminance colorimeter, optical microscope, FT-IR, TGA, DSC, XRD, the optimal UV resin formulation, and variations for BEF brightness efficiency have been examined and identified. Experimentally, the research works consist of four parts including: (1) Blend of oligomer and monomer with various indices of refraction (experimental groups coded A~F), and studied the effects of RI on the BEF brightness at a variety of prism structures and UV exposures; (2) The influence of BEF brightness for commercial UV resins by adding high RI oligomers and high RI monomers as well as mono-functional and tri-functional monomers; (3) The effects of UV resins and process conditions on the BEF product yellowness and warping; (4) The addition of colored dyes and particles into UV resins and their effects to the luminance and color hue of BEF products. Experimental results of Part One show that the higher the RI of the liquid UV resin blends, the higher the brightness; and it is not related to each individual high or low RI oligomer or monomer blends. The relationship of brightness and RI shows a direct proportion, this relationship maintains and is not affected by UV exposures and prism structure variations. Experimental results of Part Two show that blends of high RI oligomer and monomer into commercial UV resins, the relationship of brightness and RI remains a direct proportion, and the high RI monomer has more prominent effect upon brightness gain than that of high RI oligomer. In addition, blends of monomers containing different functionality, the more functional monomer showed better brightness than that of less functional monomer, this result indicates that the more functional monomer has more cross-linking density, and it causes the light passing time to extend and the refraction frequency to increase, and results in brightness gain. Experimental results of Part Three show that the degree of yellowness of UV resins is not directly related to RI or luminance variations. It is affected by the intrinsic property of UV resin or photo-initiator. For warping, it is affected by the coating and the base film thicknesses; the more the thickness, the less the warping. Also, the relationship of luminance and thickness shows an inverse proportion. Experimental results of Part Four show that colored type BEF formed by adding colored dyes can effectively mask the yellowness, while the amount of dyes is over 0.5%, the luminance will be diminished significantly. If the amount of dyes is less than 0.5%, the colored dye and the UV resin will form complementary colors and results in color mismatched. Further work is needed for dye adding ratios. The effect of adding particles into UV resin was also studied, and results show under the same amount of particle added, the larger the particle size, the more the luminance diminished. Based on the data obtained from experimental results and analyzed by Luminance colorimeter, Haze meter, FT-IR, TGA, and DSC instruments, etc., the following conclusions are achieved. FT-IR spectrum was unable to identify the relationship of cured UV resin formula to the luminance. TGA thermal analyses can clearly observed the thermal stability and decomposition rate of cured UV resin formulas. The oligomer and monomer ratio in the resin formula will affect their cured thermal property; the less oligomer can increase the thermal stability of the cured product; the hardness of UV cured film is not related only to the glass transition temperature (Tg) of UV resin, it needs to consider other factors such as MW, functionality, and the degree of UV resin cross-linking density.