Spray-applied polyurethane insulation material for tunnels in cold regions, its application, and its construction method

A method for construction of tunnels in cold regions using a spray-applied polyurethane insulation material, wherein the method comprises:

• forming a tunnel structure comprising, from outside to inside, a tunnel rock wall, a primary shotcrete layer, a geotextile layer, a self-adhesive waterproof board layer, a spray-applied polyurethane foam layer, and a secondary lining concrete layer, wherein the spray-applied polyurethane foam layer is formed by spraying the spray-applied polyurethane insulation material on a surface of the self-adhesive waterproof board layer,
• wherein the spray-applied polyurethane insulation material
• comprises a material A and a material B in a mass ratio of 0.8-1.2;
• by mass parts, the material A includes 90-100 parts of polyether polyol, 90-100 parts of polyester polyol, 5-10 parts of chain extender, 1-4 parts of catalyst, 10-20 parts of flame retardant, 0.5-3 parts of water, and 1-3 parts of surfactant;
• the material B is diphenylmethane diisocyanate;
• the flame retardant comprises a flame retardant A and a flame retardant B in a mass ratio of 10:1-2.5;
• the molecular structure of the flame retardant A is:
• wherein the flame retardant B is prepared by
• mixing DOPO, methacryloxypropyltrimethoxysilane, vinyltri(β-methoxyethoxy) silane, and triethylamine in a mass ratio of 5-6:1.8-2.5:1.5-2:0.1-0.15 as raw materials for standby;
• placing the raw materials in a supercritical CO2 reactor and sealing, then introducing CO2 gas, with the reactor pressure at 15-16.5 MPa, adjusting the reactor temperature to 40-48° C., reacting for 4-7 hours to obtain the graft product of silane and DOPO;
• and
• mixing TiO2 and the graft product of silane and DOPO in a mass ratio of 1.5-2.2:1, placing in a supercritical CO2 reactor and sealing, then introducing CO2 gas, with the reaction system temperature at 45-55° C., and the reaction system pressure at 17-19 MPa, reacting for 3-5 hours, washing the reaction product with anhydrous ethanol, and then drying to obtain the flame retardant B.