Polyurethane Composite Element Adhesion Under Thermal Stress
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Solution Overview
Problem
Existing composite elements for load-bearing constructions, such as ship hulls and high-rise buildings, face challenges in achieving uniform and bubble-free filling between metal plates with polyurethane, which can detach due to expansion differences and temperature variations, leading to poor adhesion and mechanical stress resistance.
Innovation Solution
A composite element with a layer structure of 2-20 mm metal, 10-100 mm compact polyurethane formulation made by reacting a compound with at least two isocyanate groups and polyether polyol, optionally with catalysts and additives, where the polyether polyol is a mixture of non-identical constituents, ensuring strong adhesion and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyurethane formulations are used to fill the air spaces between metal plates, then the filling process can be completed, but the polyurethane detaches from the plates due to expansion differences and temperature variations, resulting in poor adhesion
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyurethane formulation by incorporating specific additives and using a multi-component polyol system. This changes the thermal expansion characteristics and curing behavior of the polyurethane to better match the metal substrates, thereby maintaining adhesion under temperature variations.
Solution Approach 2:
The invention creates a composite material system consisting of metal plates bonded with a specially formulated polyurethane composition. The polyurethane itself is a composite of multiple polyol components and additives, designed to achieve compatible thermal and mechanical properties with the metal substrates for reliable long-term bonding.
2Strength
If the polyurethane reacts and cures between the metal plates, then adhesion is established, but the reaction products contract significantly during curing, causing detachment from the plates
Solution Approach 1:
The patent adjusts the chemical composition and molecular structure of the polyurethane formulation to control the curing shrinkage. By selecting specific polyol types and ratios, and optimizing the isocyanate index, the formulation achieves minimal volume contraction during the curing process while maintaining strong adhesion to the metal plates.
3Ease of manufacture
If standard polyurethane formulations are used, then the material can be applied easily, but the filling is non-uniform and contains air bubbles, compromising the quality of the composite element
Solution Approach 1:
The patent optimizes the rheological parameters of the polyurethane formulation by adjusting viscosity, pot life, and reactivity. The multi-component polyol system and selected additives create a formulation that remains fluid enough for complete bubble-free filling while allowing sufficient working time for proper application and distribution between the metal plates.
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 provides a composite element with enhanced adhesion and mechanical properties, including high tensile and compressive strength, and resistance to thermal expansion, ensuring durability under mechanical and dynamic stresses.
Implementation Method 1
the polyurethane being obtainable by reacting (a) a compound having at least two isocyanate groups with (b) polyether polyol
Implementation Method 2
the polyether polyol (b) is a mixture comprising at least the constituents of polyether polyol (b1) and polyether polyol (b2)... ensuring strong adhesion and mechanical properties
Implementation Method 3
Many polyurethanes have different expansion characteristics than the plates used, and so there can be detachment of the polyurethane from the plates in the event of variations in temperature
Data Source
AI summary
The disclosure provides a composite element having a layer structure with 2 mm to 20 mm of metal, 10 mm to 100 mm of compact polyurethane formulation and another 2 mm to 20 mm of metal, a method of using thereof and corresponding production process therefor. The polyurethane formulation is obtainable by reacting (a) a compound having at least two isocyanate groups with (b) polyether polyol and the polyether polyol (b) is a mixture including at least the constituents of polyether polyol (b1) and polyether polyol (b2).