One-Component Polyurethane Adhesive Self-Crosslinking
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Solution Overview
Problem
Current two-component heat-activatable polyurethane water-based adhesive compositions for thermoforming lamination require a mixing step, leading to stability issues, limited pot life, and potential allergy risks from isocyanate-based hardeners, while one-component systems lack demonstrated adhesive strength.
Innovation Solution
A one-component heat-activatable polyurethane water-based adhesive composition comprising 12-50% aqueous dispersion of polyurethane with alkoxysilyl groups and 0.5-5% glycidoxy substituted alkoxysilane, combined with a VAE copolymer and optional non-silylated polyurethane, which undergoes self-cross-linking upon drying and heating, providing improved initial and final strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a two-component heat-activatable polyurethane water-based adhesive composition is used, then adhesive strength is improved, but stability and ease of operation deteriorate due to mixing requirements and limited pot life
Solution Approach 1:
The patent combines the polyurethane dispersion and crosslinking agent into a single one-component system. The silane-modified polyurethane contains embedded alkoxysilyl groups that serve as self-crosslinking agents, eliminating the need for separate hardener components and mixing operations.
Solution Approach 2:
The adhesive system performs self-crosslinking through the thermal decomposition of blocked isocyanate groups during the drying and heating process. This self-service mechanism eliminates the need for external hardener addition and manual mixing, while maintaining high adhesive strength.
2Strength
If a two-component heat-activatable polyurethane water-based adhesive composition is used, then adhesive strength is improved, but reliability deteriorates due to stability issues and allergy risks
Solution Approach 1:
The patent extracts the isocyanate-based hardener component from the system and replaces it with silane-modified polyurethane containing blocked isocyanate groups. This extraction eliminates the allergenic isocyanate hardener while maintaining crosslinking functionality through thermal decomposition.
Solution Approach 2:
The patent uses water as the continuous phase instead of organic solvents, creating an environmentally friendly and safer adhesive system. The water-based formulation eliminates solvent-related health and safety issues while maintaining effective adhesive performance.
3Ease of operation
If a one-component heat-activatable polyurethane water-based adhesive composition is used, then ease of operation is improved, but adhesive strength deteriorates
Solution Approach 1:
The patent creates a composite adhesive system combining silane-modified polyurethane dispersion with embedded blocked isocyanate crosslinking agents. This composite structure provides both the ease of one-component application and the high strength of crosslinked adhesive bonds through thermal activation.
Solution Approach 2:
The patent utilizes thermal parameter changes during processing. The blocked isocyanate groups remain stable during storage and application at lower temperatures, then decompose and crosslink at elevated drying and heating temperatures, providing both ease of operation and high adhesive strength.
4Strength
If a two-component heat-activatable polyurethane water-based adhesive composition is used, then adhesive strength is improved, but device complexity increases due to mixing requirements
Solution Approach 1:
The patent merges the polyurethane dispersion and crosslinking agent into a single one-component formulation. The silane-modified polyurethane contains all necessary crosslinking functionality within the dispersion itself, eliminating the need for separate hardener containers, mixing equipment, and dosing systems.
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 achieves initial strength greater than 15 N/25 mm and final strength greater than 50 N/25 mm, with a shelf life of at least 6 months, and avoids the stability and allergy issues of two-component systems.
Implementation Method 1
which undergoes self-cross-linking upon drying and heating, providing improved initial and final strength
Implementation Method 2
heat-activatable polyurethane water-based adhesive composition
Implementation Method 3
This dried adhesive layer is then heated in view of its thermal activation
Data Source
AI summary
One-component heat-activatable polyurethane water-based adhesive composition, which comprises, with respect to the total weight of the adhesive composition: —from 12% to 50%, by weight of dry matter, of an aqueous dispersion of a polyurethane (A) comprising alkoxysilyl pending and/or terminal groups, and —from 0.5% to 5% by weight of a glycidoxy substituted alkoxysilane compound (B) with a glycidoxy functionality of at least 2.