透明、高折射率加成型硅橡胶的制备及改性MQ树脂的补强研究

【作者】 徐晓秋；

【导师】 伍川；

【作者基本信息】 杭州师范大学 ， 有机化学， 2010， 硕士

【摘要】 人类经历了白炽灯、荧光灯等照明历程,发展为现在的半导体照明。基于LED (Light Emitting Diode)技术的半导体照明被誉为21世纪最具有发展前景的高技术领域之一。然而基于LED的半导体照明,还存在着很多需要解决的问题,其中包括如何提高取光效率,而影响取光效率的最主要因素为封装材料。有机硅材料具有优良的耐高低温和耐辐射性能,非常适合用作LED封装材料。国内外研究者绕着有机硅封装材料展开了大量的研究,但目前国内封装用硅胶几乎全部依赖进口,不利于我国具有自主知识产权的半导体照明技术及器件的发展。功率型LED封装用有机硅材料根据用途分为树脂型和凝胶型两大类。众所周知,未经填料补强的有机硅材料机械性能极差,虽然二氧化硅是有机硅材料广泛使用的补强填料,可以大幅度提高制品的机械性能,但由于其折射率与基体材料折射率差异较大,无法满足LED封装所需光学性能指标,因此,对普通MQ树脂进行改性并以其作为光学级硅胶补强填料的研究意义重大。本论文在制备透明、高折射率加成型硅凝胶及改性MQ树脂的基础上,考察了MQ树脂作为补强材料对加成型硅橡胶的光学及机械性能的影响。论文分为以下四个部分：(1).综述了LED的发展现状及国内外封装材料的研究进展。详细的叙述了加成型硅橡胶的组成成分及其对硅橡胶性能的影响,系统地总结了MQ树脂这一新型补强填料的制备方法及其用途,并由此提出了本课题的研究目标和研究思路。(2).通过开环聚合,制备乙烯基硅氧基封端的聚(甲基苯基-二甲基-甲基乙烯基)硅氧炕。考察了聚合条件对聚合物性能的影响,包括反应催化剂、催化剂的用量、聚合时间等：在100℃下以四甲基氢氧化铵硅醇盐为催化剂,反应时间为5 h,可获得折射率最高达1.5247的透明共聚物。(3).以乙烯基硅氧基封端的聚硅氧烷为基础聚合物,硅氢基封端的聚硅氧烷为交联剂.在铂配合物的催化作用下,制备得到透明的加成型硅凝胶。考察了基础聚合物的硅乙烯基含量、交联剂的硅氢基含量及硫化温度等因素对硅凝胶硫化性能的影响：还考察了硅凝胶透光率的影响因素,发现基础聚合物和交联剂折射率的差异，催化剂对硅凝胶的透光率均有一定的影响。在此基础上：制备了透明硅凝胶,其折射率最高可达1.5247；硅凝胶在800 nm波长下的透光率达到了90%以上：400nm波长下的透光率达到80%以上：其外观清澈透明,可用于LED封装。(4).主要研究了改性MQ树脂的制备和及其补强。建立了甲基MQ树脂中M/Q比值的表征方法：研究了甲基二苯基乙氧基硅烷和二甲基苯基乙氧基硅烷为封端剂对苯基MQ树脂制备的影响。以二甲基苯基乙氧基硅烷,六甲基二硅氧烷等为封端剂,水玻璃为原料，在酸性条件下共水解可以得到折射率在1.4231·1.4990之间且可调的MQ树脂：以制备的MQ树脂为补强材料,考察了MQ树脂的加入量对基胶粘度的影响；讨论了MQ树脂甲乙烯基含量及其用量对硅橡胶力学性能的影响,在此基础上,考察了不同MePhSiO-链节含量的硅橡胶的补强效果；检测了不同MePhSiO-链节含量的硅橡胶补强后的光学性能。结果表明,制备的甲基乙烯基MQ树脂和甲基苯基乙烯基MQ树脂均不会使基胶大幅度增稠；总体而言,用MQ树脂补强MePhSiO-链节含量小于10mol%的硅橡胶时,所得硅橡胶具有良好的机械性能和光学性能。当选用乙烯基含量为1.89 wt%的甲基乙烯基MQ树脂来补强不含MePhSiO-链节的硅橡胶且用量为20 wt%时,硅橡胶的透光率为91%,拉伸强度为2.38 MPa,邵尔A硬度为31.7,扯断伸长率为70%,在400 nm波长下的透光率为91%,可满足LED封装技术要求。更多还原

【Abstract】 Illuminating instruments have developed from incandescent lamp to fluorescent lamp. Nowadays, with the rapid progress in semiconductor luminescent technology, the solid-state light source based on LED (Light emiting diode) might developed as the fourth generateon light source for human being and it was regarded as one of the most promising fields in 21st century. As a new type of light source, the main obstacle need to be overcome was focus on how to improve the extraction efficiency for Power LED. Therefore, encapsulant materials with excellent performance should be developed. Silicone material exhibits superior heat resistance, lower temprature resistance and better radiation resistance, which made it suitable for encapsulant of Power LED where large amount of heat was generated during luminance. Unfortunately, most saled encapsulant materials were relyed on import, which is not good for research and development of our national semiconductor lighting project. Power LED package material could be divided into two types, viz., silicone gel and silicone resin. As it was known by all that silicone materials exhibt poor mechanical properties if they were not reinforcened by fillers. As the most widely used fillers, although silica can greatly improve the mechanical properties of silicone materials, but it still can not reach the optic properties required by LED encapsulant due to the difference in refractive index between silica and the matrix. Therefore, it is quite interesting to investigate the modification of common MQ resin and its application in optical silicone rubber with high refractive index and transmittance. in this thesis, on the basis of the preparation of transparent, high refractive index addition silicone gel and modification of MQ resin, the modified MQ resin will be functioned as the reinforcing fillers, the optical and mechanic properties of thus obtained liquid silicone rubber will be studied in detail. This paper can be divided into four parts.(1). The progress and present situation of LED and also present the future development of encapsulate materials were briefly reviewed. The components of addittion silicone rubber and various influencing factors on its properties were discussed in detail. The preparing methods of MQ resin,a kind of novel reinforcement fillers, and its application were systematically summerized. The research goal and technical route for this thesis were subsequently presented.(2). A series of transparent vinyldimethylsiloxyl terminated poly(dimethyl-methylphenyl-methylvinyl) siloxane copolymers were prepared by ring-opening copolymerization method. Various factors, such as the catalysts, suitable amount, reaction time and so on, were carefully investigated. The result indicated that transparent copolymers with the highest refractive index (1.5247) could be obtained when the balance polymerization was conducted at 100℃for 5 h and catalyzed by tetramethylammonium hydroxide silanolate.(3). The synthesis of transparent addition silicone gel was investigated. The silicone gel was composed of three parts, viz.,matrix, crosslink agent and catalyst. The matrix was composed of vinyldimethylsiloxyl terminated polysiloxane and polysiloxane containing active Si-H bond in either backbone or end-capping position could be served as crosslinking agent for matrix. The most common catalyst used for vulcanization of addition silicone rubber or silicone gel was platinum and its complexes. It was found that the vulcanization process of addition silicone rubber and gel was greatly influenced by many factors such as the vinyl content in matrix, the amount of crosslinking agent and curing temperature, etc. Besides, the influence of catalysts and the difference in refractive index between matrix and crosslinking agent on transmittance of vulcanized products were thorouly investigated. A kind of gel-type LED encapsulant with highest refractive index (1.5247) and transmittance higher than 90% at wavelength of 800 nm or higher than 80% at wavelength of 400 nm was prepared, which is suitable for encapsulant of LED.(4). Various functionalized MQ resins were synthesized and used as the fillers in polymer system to improve its mechanical properties. In order to accurately determine the ratio between M and Q segment in MQ resin, a kind of characterization method was presented based on element analysis or’H-NMR spectrum. Phenyl containing MQ resin terminated by either methyldiphenylethoxysilane or dimethylphenylethoxysilane were prepared and the result were discussed in detail. MQ resins with refractive index ranged from 1.4231 to 1.4990 were obtained by cohydrolysis of sodium silicate and end-caping agents composed of dimethylphenylethoxy-silane and hexamethyldisiloxane in presence of acid. Subsequently, the MQ resin reinforced silicone rubber was studied in detail. The transmittance of silicone rubber reinforced by MQ resin was tested. Meanwhile, the influence of addition of MQ resin on viscosity of pre-cured mixtures was investigated and the effect of vinyl content in MQ resin and the amount of MQ resin on mechanical properties of cured silicone rubber were also discussed. The reinforcing effect of MQ resin on silicone rubber with different content of MePhSiO segment was further investigated. It was found that whether methylvinyl MQ resin or methylphenylvinyl MQ resin had little influence on viscosity of silicone rubber. In general, silicone rubber with MePhSiO segement less than 10 mol% can be reinforced by MQ resin. When MQ resin with vinyl content of 1.89 wt% was used in an amount of 20 wt%, silicone rubber free with MePhSiO segement exhibited optimal results: tensile strength was 2.38 MPa, hardness(Type A) was 31.7, elongation(%) at break was 70% and. transmittance at wavelength of 400 nm was 91%, and it is also suitable for encapsulant of LED.更多还原