Preparation of Flame Retardant and Heat Conductive Silicone Electronic Adhesive for Power Potting of Bulb Lamp

As electronic devices continue to integrate more powerful functions into smaller components, electronic components require higher flame retardancy and thermal conductivity of potting compound. Additive liquid silicone rubber is an ideal base material for electronic and electrical potting compound because of its advantages such as no by-product release during crosslinking, small shrinkage, easy control of crosslinking density and curing speed, etc. However, addition silicone rubber has poor adhesion due to its nonpolar molecules. When it is used as electronic encapsulation and coating materials, water will penetrate into the device through the gap between rubber and substrate, causing corrosion and insulation failure. The adhesion between the addition silicone material and various materials can be improved by treating the substrate surface with primer; However, this method increases the production process and production time, and the solvent volatilization during use causes unnecessary environmental pollution. Carbonate (PC) has excellent insulation, good flame retardancy and dimensional stability, and is widely used in electronic appliances as shell, body and support materials. Various amino silanes commonly used in comprehensive liquid silicone rubber have good adhesion to PC, but they cannot be used because of their toxic effect on additive liquid silicone rubber. There has been much research on this abroad, but there is no real market product at home due to the late start of the research on addition molding potting adhesive. Chen Hua et al. prepared different tackifiers and studied the adhesive properties of silicon powder filled additive potting adhesive to different substrates, but did not investigate its adhesion to PC.

In this experiment, vinyl terminated silicone oil and hydrogen containing silicone oil are used as base materials, aluminum oxide is used as thermal conductive filler, aluminum hydroxide is used as flame retardant, vinyl trimethoxysilane and γ- The mixture of methacryloyloxypropyltrimethoxysilane is used as coupling agent, platinum complex is used as catalyst, trimethylolpropane diallyl ester γ- The reaction products of epoxypropoxypropyltrimethoxysilane and tetraethyl orthosilicate were used as tackifiers to prepare two-component addition molding flame retardant and heat-conducting silicone electronic potting adhesive. The effects of hydrogen containing silicone oil, aluminum oxide, aluminum hydroxide and tackifier on the properties of potting adhesive were studied.

experiment

1. Main raw materials and equipment

Vinyl terminated silicone oil: viscosity 500mm2/s (vinyl mole fraction, 1000mm2/s (vinyl mole fraction 0.82%), Zhongshan Jingfa New Materials Co., Ltd; Hydrogen containing silicone oil: active hydrogen mass fraction 0.25%, viscosity 100mm2/s, Zhongshan Jingfa New Materials Co., Ltd; Vinyl ring: purity ≥ 99%, vinyl content ≥ 29%, Hubei Wuda Organic Silicon New Material Co., Ltd; Platinum Catalyst, Shenzhen Kejunchi Technology Co., Ltd; Aluminum oxide: content ≥ 99%, average particle size 5um and 15um, Foshan Huaya Ultrafine Powder Co., Ltd; Aluminum hydroxide: the average particle size is 7um, Foshan Huaya Ultrafine Powder Co., Ltd; Methylbutanol inhibitors; Shenzhen Kejunchi Technology Co., Ltd. Trimethylolpropane diallyl ester γ- Epoxypropoxypropyltrimethoxysilane γ- Methacryloxypropyltrimethoxysilane (A-174), vinyl trimethoxysilane (A-171), ethyl orthosilicate: Hubei Wuda Organic Silicon New Materials Co., Ltd; Butyl titanate, etc.: Inhibitor acetylene cyclohexanol (HR-04) AR, Shenzhen Kejunchi Technology Co., Ltd.

High speed dispenser: ZKJ-2, Foshan Golden Galaxy Machinery Equipment Co., Ltd; Electric thermostatic blast drying oven: DHG-9140B, Shanghai Shenxian Thermostatic Equipment Factory; Rotary viscometer: NDJ-4, Shanghai Precision Scientific Instrument Co., Ltd; High resistance meter: 6517B, Jishili Instrument Co., Ltd; Tensile testing machine CMT4303, Shenzhen New Sansi Measurement Technology Co., Ltd; Rubber hardness tester: LX-A, Shanghai Liuling Instrument Factory; Withstand voltage tester: LK2674A, Changzhou Lantian Electronics Co., Ltd.

2. Preparation of tackifier

Add a measured amount of trimethylolpropane diallyl ester γ- Epoxy propoxypropyltrimethoxysilane, tetraethyl orthosilicate and butyl titanate react at 80 ℃ for 2h, and then remove the low boiling matter under reduced pressure to obtain a pale yellow transparent liquid viscosity increasing agent with viscosity of 15, and the volatile matter is less than 2%.

3. Preparation of potting adhesive

Preparation of base material: add 100 portions of vinyl silicone oil, 150 portions of aluminum oxide and 30 portions of aluminum hydride into the high-speed disperser, mix evenly, vacuum and defoaming to obtain the base material.