Moisture-Curing Polyurethane Adhesive for Thermoformable Foam Headliners
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Solution Overview
Problem
Existing methods for producing composite parts using thermoformable rigid polyurethane foam and covering materials result in long demolding times, high production costs, and odor emissions, which are undesirable for automotive roof linings requiring excellent acoustic properties and low odor nuisance.
Innovation Solution
A method involving the use of a moisture-curing polyurethane adhesive with at least 50 wt% Isocyanate reactive groups, combined with chain extenders and crosslinking agents, which hardens upon contact with water, is applied to thermoformable rigid polyurethane foam and covering materials, allowing for faster processing and reduced odor emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If moisture-curing polyurethane adhesive with catalysts (tin-based or tertiary amines) is used to bond rigid polyurethane foam and covering material, then the adhesive bonding function is achieved, but the demolding time becomes long and production cost increases
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by using isocyanate-terminated polyurethane prepolymers with at least 50 wt% isocyanate groups and specific NCO:OH ratios (0.8:1 to 2:1), eliminating the need for traditional catalysts while achieving rapid curing and short demolding times without compromising bonding reliability
Solution Approach 2:
The patent creates a composite adhesive system combining isocyanate-terminated polyurethane prepolymers with specific polyols (polyether polyols with primary hydroxyl groups >70%) and controlled isocyanate content, forming a new material composition that simultaneously achieves fast curing, strong bonding, and low odor emissions
2Reliability
If conventional moisture-curing polyurethane adhesive is used, then adhesive bonding is achieved, but odor emissions increase and acoustic properties deteriorate
Solution Approach 1:
The patent modifies the adhesive composition by using prepolymers with at least 50 wt% isocyanate groups and specific NCO:OH ratios, combined with polyols having >70% primary hydroxyl groups, which reduces odor emissions while maintaining bonding performance and improving acoustic properties
Solution Approach 2:
The patent converts the typically harmful high isocyanate content (which would cause odor) into a benefit by using isocyanate-terminated prepolymers with controlled NCO:OH ratios (0.8:1 to 2:1) that react efficiently with water and polyols to form strong bonds without excessive odor, while the resulting composite structure improves acoustic absorption
3Ease of manufacture
If lamination with covering materials is performed after plastic deformation, then processing flexibility is maintained, but production efficiency decreases
Solution Approach 1:
The patent merges the lamination process with the plastic deformation process by applying the isocyanate-terminated polyurethane adhesive to the foam before deformation, allowing both operations to occur in one continuous step, thereby improving production efficiency while maintaining processing flexibility
Solution Approach 2:
The patent performs preliminary adhesive application before plastic deformation, allowing the adhesive to be in place and ready for immediate bonding during or after deformation, enabling process integration and improving overall production efficiency
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
This approach significantly reduces demolding times, enhances the acoustic properties of the composite parts, and minimizes odor emissions, resulting in more efficient production and improved quality of automotive roof linings with high rigidity and sound absorption.
Implementation Method 1
a moisture-curing polyurethane adhesive being used as the adhesive, which is hardened by bringing it into contact with water
Implementation Method 2
the moisture-curing polyurethane adhesive contains at least 50 wt% Isocyanate reactive group and, if appropriate, chain extenders and/or crosslinking agents are available
Data Source
AI summary
The present invention relates to a method for producing composite parts made of a thermoformable rigid polyurethane foam and a covering material, wherein a thermoformable polyurethane foam is provided and is adhesively bonded to the covering material, wherein a moisture-curing polyurethane adhesive that is cured by being brought into contact with water is used as an adhesive, and the moisture-curing polyurethane adhesive contains at least 50 wt% of an isocyanate-terminated prepolymer relative to the total weight of the moisture-curing polyurethane adhesive, wherein the isocyanate-terminated prepolymer can be obtained by mixing a stoichiometric excess of an aromatic isocyanate with high-molecular-weight compounds having at least two groups that are reactive with isocyanates, compounds having only one group that is reactive with isocyanates, and optionally a chain extender and/or cross-linking agent. The present invention further relates to a composite part that can be obtained according to such a method, and to the use of the composite part in vehicles, in particular as a headliner.