Railway ballastless track subgrade surface waterproof layer expansion joint sealing material and preparation method thereof

The invention discloses a railway ballastless track subgrade surface waterproof layer expansion joint sealing material, which comprises the following raw materials in parts by weight: 330-360 parts ofpolyisobutene, 70-90 parts of polyether ester, 40-50 parts of polysulfide modified epoxy resin, 20-25 parts of nano carbon black, 5-10 parts of hydroxypropyl methyl cellulose, 1-5 parts of ethylhexylmethoxycinnamate, 5-10 parts of a curing agent, 10-20 parts of a plasticizer, 5-8 parts of a cross-linking agent, 5-10 parts of a water removal agent and 150-200 parts of filler, wherein the polyisobutene is a mixture of polyisobutene with the molecular weight of 800 and polyisobutene with the molecular weight of 2000, and the mass ratio of the polyisobutene to the polyisobutene is 2: 1. According to the sealing material disclosed by the invention, polyisobutene, polyether ester and polysulfide modified epoxy resin are added, wherein the polyisobutene adopts two kinds of polyisobutene with different molecular weights