▎ 摘　　要

NOVELTY - Low viscosity high heat conductivity flame retardant two-component polyurethane potting sealant comprises 30-40 pts. wt. component A and 60-80 pts. wt. component B. The component A comprises 50-60 pts. wt. polyurethane pre-polymer, 20-30 pts. wt. composite flame retardant material and 10-15 pts. wt. chlorinated paraffin. The component B comprises vinyl terminated silicone oil, heat conductive filler, γ-glycidyl ether oxypropyltrimethoxysilane, amide tin catalyst, triethylenediamine, diethyl phthalate and organosilicon defoaming agent. The composite flame retardant material is formed by mixing phosphorus-containing flame retardant resin and modified expandable graphite in a ratio of 1:1. The heat conductive filler comprises ultrafine pulverized powder of aluminum oxide and nano-graphene powder in a ratio of 2:3. USE - The potting sealant is useful for bonding electronic component. ADVANTAGE - The potting sealant has low viscosity, easy operation, adjustable curing speed, excellent mechanical property, flame retardant property, heat conducting performance and electrical performance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: preparing low viscosity high heat conductivity flame retardant two-component polyurethane potting sealant comprising (a) synthesizing polyurethane pre-polymer including using dried polyether polyol, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and diphenylmethane diisocyanate to synthesize polyurethane pre-polymer through polymerization reaction body, (b) preparing phosphorus-containing flame retardant resin, modified expandable graphite and chlorinated paraffin, obtaining ultrafine pulverized powder and nano-graphene powder of aluminum oxide, obtaining the heat conductive filler based on the obtained ultrafine pulverized powder of aluminum oxide and nano-graphene powder, (c) taking polyurethane pre-polymer, phosphorus-containing flame retardant resin, modified expandable graphite, chlorinated paraffin, vinyl terminated silicone oil, heat conductive filler, γ-glycidyl ether oxypropyltrimethoxysilane, amide tin catalyst, triethylenediamine, diethyl phthalate and organosilicon defoaming agent, (d) uniformly mixing the polyurethane pre-polymer, phosphorus-containing flame retardant resin, modified expandable graphite and chlorinated paraffin with a mixer, dispersing, dehydrating to obtain component A, (e) uniformly dispersing the vinyl terminated silicone oil, heat conductive filler, γ-glycidyl ether oxypropyltrimethoxysilane, amide tin catalyst, triethylenediamine, diethyl phthalate and organosilicone defoaming agent by a high-speed disperser, vacuuming, defoaming to obtain component B and (f) mixing, stirring the obtained A component and B component, adding hollow glass microspheres to the mixture to continue low-speed dispersion and stirring to obtain low viscosity high heat conductivity flame retardant two-component polyurethane potting sealant; and a low viscosity high heat conductivity flame retardant two-component polyurethane potting sealant, which is prepared by the above method.