| Compared with condensation type liquid organic silicone,addition-cure liquid organic silicone has excellent performance such as adjustable vulcanizing time,no-products generated in the process of vulcanization and deep vulcanization,so it has been widely used as encapsulating material in electrical and electronic industry.However,addition-cure liquid organic silicone has poor adhesive property due to its surface has lots of nonpolar organic groups.In order to overcome the disadvantage of poor adhesive property of addition-cure liquid organic silicone,a novel tackifier containing epoxy group,acrylate group and vinyl group,which had excellent adhesion promoting property while used together with titanate,and applied to prepare addition-cure organic silicone encapsulant for enhancing the adhesive performance to aluminum and printed circuit board(PCB)when cured at room temperature.The main research contents and achievements are as following:Firstly,a novel tackifier(HBV)containing epoxy group,acrylate group and vinyl group was prepared through condensation of?-glycidoxypropyltrimethoxysilane(KH560),?-methacryloxypropyltrimethoxysilane(KH570)and hydroxyl-terminated vinyl siloxane(HVS)which was prepared through condensation of methyl propyl dimethoxy silane and methyl vinyl dimethoxy silane.The best synthesis conditions such as charging sequence,charging speed,reaction temperature,reaction time,catalyst concentration and reaction medium were determined after the effects of the synthesis conditions on the yield and appearance of HBV were investigated.The chemical structure of HBV was characterized by Fourier transform infrared spectroscopy(FT-IR),1H nuclear magnetic resonance spectroscopy(1H-NMR),gel permeation chromatography(GPC)and thermo gravimetric(TG).The results show that the molar ratio of HVS to KH560/KH570(nHVS/n(KH560/KH570)),dropping speed of KH560/KH570,reaction temperature,reaction time,isopropyl titanate catalyst concentration were 1.2,30 drops/min,80 ?,50 min,0.036 phr respectively.On the condition,the yield of HBV was 81%.The molecular weight of HBV was 10882g/mol.Secondly,HBV and titanate as a compound tackifier,used to improve the adhesive properties of addition-cure silicone encapsulant and aluminum,PCB.The effect of the amount of HBV and titanate on viscosity,cure characteristics,adhesive property,mechanical property,electrical properties,storage stability and adhesivestability of addition-cure silicone encapsulant was investigated.The results show that when the molar ratio of H-Si to CH2CH-Si was 1.4,the bonding shear strength of addition-cure silicone encapsulant with aluminium product and with PCB substrate has reached 0.92 MPa and 0.88 MPa respectively with addition of 2.0phr HBV and0.5phr titanate while curing at room temperature(25?).In aditional,the addition-cure silicone encapsulant shows good electrical properties,storage stability and adhesion stability.Thirdly,The compound tackifier can significantly improve the adhesion of additon-cure silicone encapsulant and LED drive power,so that the LED drive power has excellent anti-aging performance.The LED drive power can pass the tested by 6cycles of salt and moist-resistance aging test,30 days high temperature and humidity aging test,60 cycles of thermocycling aging test,30 days high temperature aging test,30 days water soaking aging test and 5 hours water boiling aging test. |
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