Moisture-Curing Polyurethane Composition for Residual Bead Adhesion
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Solution Overview
Problem
Existing single-component moisture-curing polyurethane adhesives face challenges in achieving good adhesion to difficult substrates like residual adhesive beads, particularly those that are aged or brittle, leading to issues such as water ingress and wind noise in vehicle windshields, while maintaining properties like storage stability, curing speed, and elasticity.
Innovation Solution
A moisture-curing polyurethane composition comprising an isocyanate-containing polyetherurethane polymer with 80% 1,2-propyleneoxy units and a hydrophobic polymer derived from hydrophobic diols, such as dimer fatty acid-based polyester diols, in a specific weight ratio, which enhances adhesion to residual adhesive beads without compromising other properties like extrusion ease and weather resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If known 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 chemical parameters by using a specific polyether polyol with at least 80% 1,2-propyleneoxy units, which modifies the polymer structure to achieve both adhesion to residual adhesive beads and retention of elasticity, resolving the contradiction between strength and adaptability
Solution Approach 2:
The patent creates a composite polyurethane system combining polyetherurethane polymer with specific polyether polyol characteristics, achieving synergistic effects that provide both adhesion promotion and elasticity maintenance that neither component could achieve alone
2Strength
If the adhesive is designed to adhere to aged and brittle residual adhesive beads, then adhesion is improved, but water ingress and wind noise occur when adhesion fails
Solution Approach 1:
The patent applies beforehand cushioning by ensuring the adhesive maintains elasticity even when adhering to brittle substrates, creating a buffer that prevents catastrophic failure and subsequent water ingress or wind noise
Solution Approach 2:
The patent modifies the chemical composition parameters of the polyether polyol to achieve optimal balance between adhesion strength and elasticity, ensuring reliable performance that prevents water ingress and wind noise
3Reliability
If hydrophobic diols are used in two-component polyurethanes to improve cold flexibility and weathering stability, then weather resistance is improved, but they are rarely suitable for one-component moisture-curing systems
Solution Approach 1:
The patent achieves universality by selecting polyether polyols that simultaneously provide the weathering stability typically associated with hydrophobic diols in two-component systems while maintaining compatibility and performance in one-component moisture-curing systems
Solution Approach 2:
The patent changes the parameter of polyether content and structure to create a material that exhibits weathering stability comparable to hydrophobic diol systems while maintaining the ease of use of one-component moisture-curing adhesives
4Strength
If adhesion promoters are added to improve adhesion to residual adhesive beads, then adhesion is improved, but curing speed may be affected
Solution Approach 1:
The patent optimizes the molecular weight and functional group parameters of the polyether polyol to achieve adhesion promotion without interfering with the isocyanate curing mechanism, maintaining fast curing speed
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 composition provides improved adhesion to residual adhesive beads with a long open time, excellent extrusion properties, high weather resistance, and maintained strength and elasticity, suitable for vehicle construction applications.
Implementation Method 1
single-component, moisture-curing systems
Implementation Method 2
isocyanate-containing polyetherurethane polymer
Implementation Method 3
hydrophobic polymer containing isocyanate groups P2 based on a hydrophobic diol
Data Source
AI summary
The present invention relates to a moisture-curing composition that is liquid at ambient temperature and optionally highly viscous, containing: - at least one polyether urethane polymer (P1) containing isocyanate groups and having a content of at least 80 % by wt. 1,2-propyleneoxy units in the polyether segment, and - at least one hydrophobic polymer (P2) containing isocyanate groups and being liquid at ambient temperature, obtained by reacting at least one monomeric diisocyanate and a hydrophobic diol having an OH-number ranging between 28 and 120 mg KOH/g, the polymers P1 and P2 being produced separately and said polymers P1 and P2 having a weight ratio ranging between 70/30 and 98/2. Thanks to the presence of the hydrophobic polymer (P2), the composition according to the invention exhibits 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.