A New Dealcoholization Method in the Synthesis of Vinyl Methyl Phenyl Silicone Resins for LED Encapsulation
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ORIGINAL PAPER
A New Dealcoholization Method in the Synthesis of Vinyl Methyl Phenyl Silicone Resins for LED Encapsulation Zhaoqun Pan 1 & Kelin Zeng 1 & Bingsheng Huang 1 & Liqiang Zhu 1 Received: 29 October 2019 / Accepted: 28 January 2020 # Springer Nature B.V. 2020
Abstract The oligosiloxane resins were synthesized through hydrolytic sol-gel reaction and remained many hydroxyl groups, which did great harm to the curing process and resulted in poor performance of the cured products. In previous works, epoxy-modified silicone resins were synthesized by dealcoholization, a reaction between 3-glycidoxypropylmethyldimethoxysilane and terminal hydroxyl groups in phenyl silicone resins. Although this method eliminated the hydroxyl groups, it caused a large loss of vinyl groups inevitably and a poor stability of cured products. In this study, methyltrimethoxysilane (MTMS) was used to eliminate hydroxyl groups containing in vinyl methyl phenyl silicone resins, which were synthesized through hydrolytic sol-gel reaction. Most of residual hydroxyl groups were deleted effectively and the great loss of vinyl groups were avoided in the dealcoholization reaction. Then, the methyl phenyl silicone materials were fabricated by hydrosilylation reaction between the synthesized vinyl methyl phenyl silicone resins and hydrogen-containing ones. The cured silicone materials showed excellent optical performance (~ 89.1% at 450 nm) and good adhesion performance. In addition, due to less vinyl loss in the vinyl methyl phenyl silicone resins, the cured methyl phenyl silicone materials exhibited higher cross-linking density, better thermal resistance (5% mass loss at 435 °C) and better mechanical properties (50 shore D) compared with the epoxy-modified phenyl silicone materials. The lumen depreciation (working 168 h at 50 mA) and reflow soldering tests further demonstrated the methyl phenyl silicone materials possessed good thermal stability. These results indicated that the methyl phenyl silicone materials could be used as a LED encapsulant with a good performance. Keywords LED packaging . Hydrolytic sol-gel . Non-hydrolytic sol-gel . Vinyl methyl phenyl silicone resin . Methyltrimethoxysilane
1 Introduction Owing to the superior advantages such as high light extraction efficiency, long-term durability and energy conservation, light-emitting diodes (LEDs) are considered as ideal illumination source. Currently, high power LEDs has been widely applied in automotive illumination, electronic displays, daily lighting and signal displays [1]. Theoretically, LEDs can continuously light for more than 100,000 h under ideal environment. However, in practical application, the actual lifetime of
* Zhaoqun Pan [email protected] 1
School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou City, Guangdong Province 510640, P.R.China
LEDs is much lower than the expected one because of electrical, thermal, chemical influence and mechanical stress [2, 3]. The demand for high perform
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