High-Fiber Polyurethane Railway Sleeper Impregnation
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Solution Overview
Problem
Current railway sleepers, including reinforced concrete, wooden, and fiber-reinforced polyurethane foam composites, fail to meet the strength, fatigue resistance, and anti-pulling requirements for heavy loading and high-speed railways due to low fiber content and poor impregnation of polyurethane and fibers, leading to instability and high production costs.
Innovation Solution
A fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content is created by using a formulation of polyether polyol, isocyanate, and reinforcing fibers, with a continuous molding process and coupling agents to enhance impregnation and bonding, resulting in a product with improved strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fiber content is increased to improve strength and fatigue resistance, then the sleeper's mechanical properties are improved, but the impregnation uniformity of polyurethane and fiber deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the polyurethane system by using polyether polyol with specific hydroxyl value (400-480) and functionality (1-3), and adjusting the isocyanate-to-polyol ratio to 1.05-1.15. These parameter changes optimize the reaction characteristics to achieve both high fiber content (60-80%) and uniform impregnation, resolving the contradiction between strength improvement and impregnation uniformity
Solution Approach 2:
The patent introduces a coupling agent as an intermediary substance that promotes uniform bonding between the polyurethane matrix and fiber reinforcement. The coupling agent facilitates consistent impregnation across high fiber content compositions, enabling both improved mechanical properties and stable impregnation uniformity simultaneously
2Productivity
If polyurethane curing is accelerated to improve production efficiency, then the curing time is reduced, but the impregnation quality of fiber and resin deteriorates
Solution Approach 1:
The patent optimizes the reaction parameters by selecting polyether polyol with hydroxyl value 400-480 and functionality 1-3, and controlling the isocyanate-to-polyol ratio at 1.05-1.15. These parameter changes enable the system to achieve fast curing (completing in 3-5 minutes) while maintaining uniform impregnation quality, resolving the contradiction between productivity and manufacturing precision
3Quantity of substance
If fiber content is increased to reduce material cost, then the production cost is reduced, but the local fiber distribution and foam pore uniformity deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by using polyether polyol with specific hydroxyl value and functionality, and adjusting the isocyanate-to-polyol ratio. These parameter changes optimize the polyurethane reaction characteristics to achieve uniform foam expansion and consistent local fiber distribution even at high fiber content (60-80%), preventing clumping and ensuring homogeneous composition throughout the sleeper
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 solution achieves a fiber content greater than 60% and density higher than 840 kg/m³, significantly enhancing the sleeper's strength, fatigue resistance, and water resistance, while reducing production costs and simplifying manufacturing processes.
Implementation Method 1
a polyurethane resin as a matrix material and a fiber as a reinforcing material. With parts by mass, a formulation of the polyurethane resin and the mass ratio of the polyurethane resin to the reinforcing fiber are as follows: Polyether polyol A having a hydroxyl value of 400 - 480 and a functionality of 1 - 390 - 95 parts Polyether polyol B having a hydroxyl value of 60 - 160 and a functionality of 1 - 25 - 10 parts Isocyanate100 - 135 parts
Implementation Method 2
Foaming agent0.1 - 1 part
Data Source
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AI summary
A fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content and a manufacturing method thereof are disclosed. The railway sleeper is formed by bonding a plurality of fiber-reinforced rigid polyurethane foam composite boards with high fiber content (10) by a binder (11), and the outer surface of the railway sleeper is provided with an anticorrosive paint film (12). The fiber-reinforced rigid polyurethane foam composite boards with high fiber content (10) include a polyurethane resin as a matrix material and a fiber as a reinforcing material. In the present invention, the problem of insufficient impregnation of the polyurethane and the fiber is solved by using a plurality of technical means such as using a mixed polyether polyol having a low hydroxyl value and a low functionality, using a coupling agent, etc., thus the fiber content is increased and a fiber-reinforced rigid polyurethane foam composite product having a density higher than 840 kg/m3 and a fiber content greater than 60% is capable of being manufactured, which fills in the technical gap of fiber-reinforced rigid polyurethane foam composite railway sleepers and makes a diversification of the product specifications and performance to meet various technical requirements.