Aqueous Polyurethane Dispersion Bonding Without High Temperature Activation
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Solution Overview
Problem
Existing aqueous polyurethane dispersions require high temperature activation for bonding, which can damage sensitive substrates, and attempts to reduce activation temperature using solvents or plasticizers result in undesirable loss of bond strength, while there is a need for a versatile adhesive that maintains bonding properties across a wide temperature range, including low temperatures, and after exposure to humid or high-temperature conditions.
Innovation Solution
An aqueous dispersion comprising a mixture of polyurethane polymers formed from specific polyisocyanate and polyol compounds, including polyester and polycarbonate polyols, with a controlled molar ratio and molecular weight, along with emulsifiers and isocyanate-reactive compounds, which can bond substrates without high temperature activation and maintain bonding strength under varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high temperature activation is used for bonding, then bonding strength is improved, but substrate damage occurs
Solution Approach 1:
The invention changes the chemical composition parameters of the polyurethane polymer by controlling the molar ratio of polyester to polycarbonate polyols (from 35/65 to 75/25) and using polyols with Mn ≥ 500 g/mol, which modifies the polymer's thermal properties to enable bonding at lower temperatures while maintaining bond strength
Solution Approach 2:
The invention creates a composite polyurethane system combining polyester polyol segments and polycarbonate polyol segments in specific ratios, resulting in a material that exhibits both adequate thermal activation capability and reduced thermal damage to substrates
2Temperature
If solvents or plasticizers are added to reduce activation temperature, then activation temperature is reduced, but bond strength is lost
Solution Approach 1:
The invention changes the fundamental chemical structure parameters of the polyurethane by controlling polyol composition and molecular weight (Mn ≥ 500 g/mol), enabling temperature reduction without requiring solvents or plasticizers that would compromise bond strength
Solution Approach 2:
The invention replaces the need for temporary solvents or plasticizers with a permanently structured polyol composition that inherently provides the desired temperature reduction while maintaining long-term bond strength
3Object-affected harmful factors
If contact bonding without temperature activation is used, then substrate damage is avoided, but bonding versatility is limited
Solution Approach 1:
The invention creates a polyurethane adhesive composition that can function in multiple bonding modes (contact bonding, wet assembly, pressure-sensitive bonding) and across wide temperature ranges, making it universally applicable to different substrates and assembly methods while avoiding substrate damage
Data Source
AI summary
The present invention concerns an aqueous dispersion comprising water and a mixture of:A) an aqueous dispersion comprising water and a polyurethane polymer A-1) obtained by reacting at least the following components:(a) a polyisocyanate compound;(b) a polyol compound comprising:(c) an emulsifier;B) an aqueous dispersion other than A) comprising water and a polyurethane polymer B-1) obtained by reacting at least the following components:(i) a diisocyanate;(ii) at least one polyether polyol having a number average molecular weight (Mn) ranging from 500 to 10 000 g/mol;(iii) an amino compound having an amino functionality higher or equal to 1;(iv) a compound comprising at least one isocyanate-reactive group and at least one ionic or potentially ionic group;wherein said polyurethane B-1) is amorphous.