Aqueous Polyurethane-Polyurea Adhesive Dispersion for Delayed Bonding
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Solution Overview
Problem
Existing adhesive technologies for temperature-sensitive substrates lack storage stability at temperatures above 50°C and require immediate mixing of components, limiting the separation of application and bonding processes in time and space, which is economically undesirable.
Innovation Solution
An aqueous dispersion containing semicrystalline polyurethane-polyurea polymer and surface-deactivated polyisocyanate, with a melting temperature of at least 55°C, allowing for storage-stable adhesive layers that can be applied separately in time and space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polyurethanes with melting temperature below 50°C are used for heat-activated adhesive bonding, then the adhesive can be applied to temperature-sensitive substrates, but the heat resistance and storage stability are insufficient at temperatures above 50°C
Solution Approach 1:
The patent changes the melting temperature parameter of the polyurethane polymer from below 50°C to at least 55°C, thereby improving storage stability and heat resistance while maintaining applicability to temperature-sensitive substrates through the use of aqueous dispersion and controlled application temperatures
2Reliability
If a two-component system with liquid polyisocyanate crosslinker is used, then hydrolysis resistance and heat resistance are improved, but the technical complexity and susceptibility to errors increase
Solution Approach 1:
The patent merges the polymer and crosslinker into a single one-component aqueous dispersion system, eliminating the need for separate mixing and handling of two components while maintaining the crosslinking functionality and hydrolysis resistance through stable incorporation of surface-deactivated polyisocyanate particles
Solution Approach 2:
The patent uses surface-deactivated polyisocyanate particles as an intermediary form that allows the crosslinker to be stored stably in the dispersion without premature reaction, enabling one-component operation while preserving the crosslinking functionality for later activation during drying or heating
3Reliability
If two-component adhesive systems are used, then improved adhesive properties are achieved, but the operating steps of application and joining cannot be separated in time and space
Solution Approach 1:
The patent segments the adhesive process into separate application and joining stages by providing a storage-stable one-component dispersion that can be applied first, dried to form a stable adhesive layer, and then joined later when needed, eliminating the requirement for immediate two-component mixing and immediate bonding
4Strength
If crosslinking reaction is initiated immediately upon mixing, then adhesive strength is improved, but the adhesive layer loses flowability and cannot be stored or transported
Solution Approach 1:
The patent incorporates the crosslinker into the dispersion in advance but deactivates its reactivity through surface treatment, allowing the adhesive to be prepared, applied, and stored in advance without premature crosslinking, with the crosslinking reaction activated later during the drying or heating stage
Solution Approach 2:
Surface deactivation of polyisocyanate particles acts as an intermediary mechanism that prevents premature crosslinking reaction while maintaining the potential for crosslinking activation during subsequent drying or heating processes
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 storage-stable adhesive layers that can be stored for months at temperatures above 50°C without premature crosslinking, enabling separate application and bonding processes, suitable for decorative films in varying climates.
Implementation Method 1
the melting temperature of the semicrystalline polyurethane-polyurea polymer is at least 55° C.
Implementation Method 2
aqueous dispersion containing at least one semicrystalline polyurethane-polyurea polymer
Data Source
AI summary
The present disclosure relates to an aqueous dispersion containing at least one semicrystalline polyurethane-polyurea polymer and at least one surface-deactivated polyisocyanate. The melting temperature of the semicrystalline polyurethane-polyurea polymer is at least 55° C. The disclosure also relates to a process for preparing the aqueous dispersion, the use of the aqueous dispersion for producing coated substrates or adhesive films, flat or three-dimensional substrates coated with the aqueous dispersion, a substrate coated with at least one semicrystalline polyurethane-polyurea polymer and at least one surface-deactivated polyisocyanate, an adhesive film including at least one semicrystalline polyurethane-polyurea polymer and at least one surface-deactivated polyisocyanate, and a dried adhesive film obtained from such an aqueous dispersion.