Spring Urethane Coating Composition for Heat and Stone-Chip Durability
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Solution Overview
Problem
Current coating agents for springs lack durability and impact resistance, especially at normal and high temperatures, and do not adequately address the requirements for applications involving repeated expansion and contraction, contact between spring lines, and resistance to stone chips.
Innovation Solution
A coating agent with a cured product that has a tear strength of 20 kN/m or more at 25° C. and 80° C., and type A durometer hardness of 30 to 100 at 25° C., composed of a polymeric polyol, isocyanate, and chain extender, or a prepolymer reaction product, forming a urethane-based layer for enhanced durability and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coating agents are used on springs, then basic corrosion resistance is provided, but durability at high temperature and impact resistance at low temperature are insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the coating agent by incorporating specific polymeric polyols (polycarbonate-based, polyether-based with bisphenol structure, lactone-based, polyester-based) and controlling molecular weight distributions. These parameter changes enable the cured coating to achieve tear strength of 20 kN/m or more at both 25°C and 80°C while maintaining type A durometer hardness between 30-100, resolving the contradiction between reliability under thermal stress and mechanical strength.
Solution Approach 2:
The patent creates a composite coating system combining multiple polyol types with isocyanates and chain extenders to form a cross-linked polyurethane network. This composite material structure integrates the advantages of different polyol families - polycarbonate for thermal stability, polyether for flexibility, and polyester for adhesion - achieving both high-temperature durability and impact resistance simultaneously.
2Object-affected harmful factors
If the coating layer is made harder to improve durability, then resistance to stone chips improves, but noise from spring contact increases
Solution Approach 1:
The patent achieves different local properties within the coating system by controlling the cross-linking density and molecular structure of the polyurethane network. The coating formulation allows the surface layer to have sufficient hardness for chip resistance while the bulk maintains lower hardness for noise reduction, creating a gradient structure that satisfies both contradictory requirements.
Solution Approach 2:
By adjusting the type and ratio of polymeric polyols and chain extenders, the patent optimizes the molecular weight and cross-linking density parameters of the cured coating. This enables precise control of the hardness parameter to fall within the type A durometer 30-100 range, balancing chip resistance with noise reduction capabilities.
3Reliability
If the coating is made thicker to improve durability against repeated expansion and contraction, then resistance to fatigue improves, but the complexity of the coating process increases
Solution Approach 1:
The patent extracts the fatigue resistance function from thickness-dependent properties and transfers it to composition-dependent properties. By formulating the coating with specific polymeric polyols and cross-linking agents, the coating achieves high durability against repeated expansion and contraction through enhanced molecular network stability rather than increased thickness, simplifying the coating process.
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 coating agent provides a cured product layer with excellent durability at normal and high temperatures and impact resistance at low temperatures, preventing damage from repeated stress and stone chips, while maintaining lower hardness than steel to prevent noise.
Implementation Method 1
the cured product after curing is a cured product having a urethane bond
Implementation Method 2
A coating agent, a cured product of which after curing having a tear strength, at each of 25° C. and 80° C., of 20 kN/m or more
Data Source
AI summary
A coating agent, a cured product of which after curing having a tear strength, at each of 25° C. and 80° C., of 20 KN/m or more, and having a type A durometer hardness at 25° C. of from 30 to 100, and a spring using the same.