Isocyanate Polyester Urethane for Elastic Vehicle Glass Adhesion
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Solution Overview
Problem
Existing moisture-curing polyurethane adhesives struggle to achieve good adhesion to residual adhesive beads on vehicle substrates without compromising elasticity, storage stability, and hazardous substance classification, and often require complex manufacturing processes.
Innovation Solution
A dimer fatty acid-based polyester diol and monomeric diisocyanate polymer with controlled NCO and monomeric diisocyanate content, allowing for a liquid, room-temperature processable adhesive that improves adhesion to residual adhesive beads with enhanced weather resistance and reduced hazardous substance classification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesion promoters such as diisocyanate oligomers are used to improve adhesion to residual adhesive beads, then adhesion is improved, but elasticity of the adhesive is lost
Solution Approach 1:
The patent changes the molecular weight parameters of the polyester diol to a specific range (1,500-5,000 g/mol) and controls the NCO content (1.5-6 wt%) to achieve optimal balance between adhesion and elasticity. This parameter optimization allows the polymer to penetrate residual adhesive beads effectively while maintaining flexible chain structures that preserve elasticity.
Solution Approach 2:
The patent creates a composite system by combining dimer fatty acid-based polyester diol with monomeric diisocyanate in specific ratios, forming a polymer with dual characteristics: the polyester backbone provides elasticity and flexibility, while the isocyanate groups provide adhesion capability. This composite approach at molecular level resolves the contradiction between adhesion strength and elasticity.
2Strength
If monomeric diisocyanates are used in high concentrations to achieve good adhesion, then adhesion is improved, but hazardous substance classification worsens
Solution Approach 1:
The patent optimizes the monomeric diisocyanate content parameter to a specific range (0.1-3.0 wt%, preferably 0.2-1.0 wt%). This controlled concentration provides sufficient adhesion through the polyester chain structure while keeping free monomer levels below hazardous thresholds, thus resolving the contradiction between adhesion performance and safety classification.
3Strength
If dimer fatty acid-based polyester polyol with high NCO content is used, then adhesion is improved, but the composition becomes too inelastic and forms bubbles during curing
Solution Approach 1:
The patent carefully balances the NCO content parameter within 1.5-6 wt% and molecular weight within 1,500-5,000 g/mol. This controlled NCO content provides adequate crosslinking for adhesion while preventing excessive crosslinking that would cause brittleness and bubble formation. The molecular weight range ensures the polymer remains processable at room temperature while achieving good adhesion.
4Strength
If complex multi-stage reaction products are used to achieve high early strength, then strength is improved, but manufacturing complexity and viscosity increase
Solution Approach 1:
The patent extracts and eliminates complex multi-stage reaction processes from the manufacturing procedure. Instead, it uses a simplified single-stage reaction between dimer fatty acid-based polyester diol and monomeric diisocyanate under controlled conditions. This extraction of unnecessary process complexity reduces manufacturing steps while maintaining high early strength through optimized polymer structure.
Solution Approach 2:
The patent optimizes reaction parameters including NCO/OH ratio (0.8-2.0), temperature (50-100°C), and time (2-24 hours) to achieve high early strength in a single stage. This parameter optimization replaces complex multi-stage processes with a streamlined procedure that maintains strength performance while reducing manufacturing complexity.
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 polymer provides improved adhesion to residual adhesive beads, maintains elasticity and stability, and reduces hazardous substance classification risks, while being easily processable at room temperature and offering better weather resistance.
Implementation Method 1
moisture-curing polyurethane compositions, which are suitable for use as adhesives and are based on at least one isocyanate group-containing polymer and at least one further polymer
Data Source
AI summary
The present invention relates to a polyester urethane polymer containing isocyanate groups and being liquid at ambient temperature, obtained by reacting at least one monomeric diisocyanate and a dimer fatty acid-based polyester diol having an OH-number ranging between 28 and 120 mg KOH/g in a NCO/OH ratio of at least 3/1, and by subsequently removing a large part of the monomeric diisocyanate by means of a suitable separation process, characterised in that said polymer has an NCO content ranging between 1.5 and 6 % by wt. and a maximum monomeric diisocyanate content of 0.5 % by wt. The invention also relates to the use of said polymer as an adhesion promoter and to moisture-curing polyurethane compositions containing said polymer. The polymer according to the invention is easy to use. It permits the production of moisture-curing polyurethane compositions for application in ambient temperatures, having improved properties in terms of open time, adhesion, application and weather resistance, with unchanged good properties of storage stability, curing rate, strength, ductility, elasticity and hazardous material classification. Compositions of this type are particularly suitable for use as elastic adhesives in replacement glass for vehicles.