Spray Polyurethane Tunnel Insulation With Flame-Retardant Closed Cells
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Solution Overview
Problem
Existing spray-applied polyurethane materials for tunnels in cold regions face issues such as flammability, gaps in insulation layers, air leakage, and poor adhesion in low-temperature environments, leading to reduced insulation effectiveness and safety concerns.
Innovation Solution
A spray-applied polyurethane insulation material composed of specific ratios of polyether and polyester polyols, diphenylmethane diisocyanate, and a synergistic flame retardant system, combined with a construction method that ensures tight layer adhesion and insulation performance, using a two-component high-pressure spray foaming machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spray-applied polyurethane material is used for insulation in tunnels, then insulation performance is improved, but flammability increases causing safety hazards
Solution Approach 1:
The patent uses composite flame retardant materials including phosphorus-containing compounds, nitrogen-containing compounds, and metal hydroxides combined with the polyurethane insulation material. This composite approach provides both insulation performance and flame retardancy, resolving the contradiction between insulation effectiveness and fire safety in tunnel applications.
Solution Approach 2:
The patent converts the harmful flammability of polyurethane into a beneficial flame-retardant property by incorporating flame retardant additives that release fire-retardant gases and form protective char layers when exposed to fire, thereby protecting the tunnel structure while maintaining insulation performance.
2Reliability
If rigid polyurethane insulation layer is constructed with boards, then insulation coverage is improved, but construction efficiency decreases due to gaps between boards
Solution Approach 1:
The patent replaces the mechanical board installation system with a spray-application system that delivers polyurethane insulation material in a foam form. This substitution eliminates the need for manual placement and joining of rigid boards, achieving continuous coverage without gaps while significantly improving construction speed and efficiency.
Solution Approach 2:
The patent changes the physical state of the insulation material from rigid boards to sprayable foam, allowing the material to flow and conform to the tunnel surface. This parameter change enables complete coverage of complex geometries without gaps or joints, resolving the contradiction between coverage quality and construction efficiency.
3Productivity
If spray-applied polyurethane foam is used for insulation, then construction efficiency is improved, but air trapped in insulation layer causes leakage reducing insulation performance
Solution Approach 1:
The patent optimizes the foaming parameters including expansion ratio, cell structure density, and curing conditions to produce a closed-cell foam structure. This parameter optimization ensures that air bubbles are uniformly distributed and trapped in a controlled manner, preventing air leakage while maintaining the insulation performance and construction efficiency benefits of spray application.
4Reliability
If polyurethane insulation is applied in low-temperature environments, then insulation effectiveness is improved for cold regions, but adhesion and foaming performance deteriorate
Solution Approach 1:
The patent adjusts the chemical composition parameters of the polyurethane system including selecting polyols with appropriate molecular weights and structures, and optimizing catalyst types and dosages. These parameter changes enable the material to maintain good adhesion and proper foaming characteristics at low temperatures, resolving the contradiction between insulation effectiveness in cold regions and manufacturability.
Solution Approach 2:
The patent uses composite polyol systems combining different types of polyols (polyester and polyether) with complementary properties, along with specialized additives for low-temperature performance. This composite formulation maintains adhesion and foaming performance in cold environments while ensuring effective insulation in tunnel applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The material achieves high flame retardancy, excellent insulation performance with a closed-cell structure, and prevents air and water ingress, enhancing tunnel safety and operational efficiency.
Implementation Method 1
spray-applied polyurethane foam layer
Implementation Method 2
air trapped in the insulation layer
Implementation Method 3
flame retardant performance
Implementation Method 4
insulation performance
Implementation Method 5
supercritical CO2 reactor, reactor pressure at 15-16.5 MPa, adjusting the reactor temperature to 40-48° C.
Data Source
AI summary
The present invention provides a spray-applied polyurethane insulation material for tunnels in cold regions, its application, and its construction method. The spray-applied polyurethane insulation material for tunnels in cold regions is composed of raw materials with a mass ratio of 0.8-1.2 of material A and material B. By mass parts, 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 B component is diphenylmethane diisocyanate. The flame retardant is composed of flame retardant A and flame retardant B in a mass ratio of 10:1-2.5. The spray-applied polyurethane insulation material of the present invention is used to construct tunnel structures in cold regions, providing good flame retardant and insulation effects.