Two-Component Hot-Melt Adhesive with Silane Crosslinking
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Solution Overview
Problem
Existing moisture-curing two-component (2K) adhesives and sealants based on silane-crosslinking polymers face limitations in achieving quick initial adhesion and resilient bonding without the use of heavy metal catalysts, as they are often highly viscous and require water diffusion for crosslinking, which is slow and can lead to bubble formation.
Innovation Solution
A 2K composition comprising a liquid polyoxyalkylene or polyacrylate prepolymer with hydrolyzable silane groups and a solid inert additive, along with a component containing crosslinking agents, water-absorbing substances, and auxiliaries, which allows for rapid curing and elastic bonding without metal catalysts, ensuring quick initial adhesion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If moisture-curing 1K adhesives are used to achieve quick initial adhesion, then initial bond strength is improved, but final curing is limited by the diffusion rate of water in the adhesive
Solution Approach 1:
The adhesive system is divided into two separate components: Component A (silane-functional polyoxyalkylene prepolymer) and Component B (crosslinking compounds, water-absorbing substances, and auxiliaries). This segmentation allows Component A to provide immediate adhesive properties upon application, while Component B enables rapid crosslinking when mixed, resolving the contradiction between fast initial adhesion and efficient final curing.
Solution Approach 2:
Water-absorbing substances act as intermediaries that control the availability of water for crosslinking. These substances absorb excess water and release it gradually, facilitating rapid crosslinking without the limitations of water diffusion through the adhesive mass, thus improving final curing speed while maintaining quick initial adhesion.
2Productivity
If NCO-crosslinking systems are used to achieve rapid curing, then crosslinking speed is improved, but addition of water leads to bubble formation that impairs functionality
Solution Approach 1:
Water, which traditionally causes bubble formation and functional impairment in NCO-crosslinking systems, is converted into a beneficial crosslinking agent through silane chemistry. The silane-functional prepolymers react with water to form siloxane crosslinks, eliminating bubble formation while maintaining rapid curing capability and preserving adhesive functionality.
Solution Approach 2:
The crosslinking chemistry is changed from NCO-based to silane-based crosslinking. This parameter change allows water to serve as a beneficial reactant rather than a harmful contaminant, enabling rapid curing without bubble formation and maintaining adhesive functionality throughout the process.
3Stability of the object's composition
If 2K adhesives are used to achieve good storage stability, then storage stability is improved, but the adhesive remains flowable immediately after application and does not produce resilient initial bond
Solution Approach 1:
The adhesive utilizes phase transition of the solid inert additive (softening point 40-150°C) to achieve both good storage stability and strong initial bond. The additive remains solid during storage, providing stability, but melts at application temperature to enable proper flow and bonding, then resolidifies to provide resilient initial bond strength.
Solution Approach 2:
The adhesive combines silane-functional polyoxyalkylene prepolymer with solid inert additives having specific softening points. This composite material structure provides storage stability through the solid additive while enabling initial bond strength through controlled melting and resolidification behavior during application.
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 2K composition with rapid curing and excellent initial strength, maintaining adhesion and elasticity even under varying conditions, including low humidity, and is suitable for diverse substrates and applications.
Implementation Method 1
a prepolymer with at least one hydrolyzable silane group
Implementation Method 2
crosslink by hydrolyzable silane groups
Implementation Method 3
2 to 60% by weight of water-absorbing substances
Implementation Method 4
at least one at room temperature (25 °C) solid inert additive with a softening point of 40 to 150 °C
Implementation Method 5
the 2K composition and component A having hot melt adhesive properties
Data Source
AI summary
The invention relates to a moisture-curing two-component composition consisting of a component A which contains at least one polyoxyl alkylene, polyolefin, and/or polyacrylate prepolymer with at least one hydrolyzable silane group and which contains at least one solid inert additive, selected from hydrocarbons, polyesters, or polyamides; a component B which contains at least one compound that crosslinks the prepolymers; and auxiliary agents and additives in one or both components, wherein the component A and the two-component composition each have hot-melt adhesive properties.