One-Part Polyurethane Sealant for Low-Temperature Extrusion and Curing
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Solution Overview
Problem
Existing one-component polyurethane compositions face challenges in low temperature environments, such as cold climates, with increased viscosity leading to application difficulties and slowed curing due to reduced moisture availability, which current solutions like catalyst enhancement or two-component systems fail to adequately address.
Innovation Solution
A one-part polyurethane composition comprising specific weight percentages of isocyanate-functional polyurethane polymer, organic thixotropy agent, plasticizer, and catalyst, optimized for low temperatures, with a controlled NCO content and minimal monomeric MDI, ensuring low viscosity and fast curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If one-component polyurethane composition is used for low temperature application, then ease of operation is improved, but viscosity increases significantly making application difficult
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating specific low-viscosity plasticizers (2-25 wt%), solvents (0-15 wt%), and rheology modifiers (5-20 wt%) to control the viscosity of the polyurethane composition at low temperatures, enabling application without excessive extrusion force while maintaining one-component simplicity
Solution Approach 2:
The patent creates a composite formulation combining polyurethane polymer, plasticizers, solvents, rheology modifiers, and catalysts in specific proportions to achieve a balanced composition that maintains operability at low temperatures without requiring two-component mixing
2Device complexity
If one-component polyurethane composition is used for low temperature application, then device complexity is reduced, but curing rate slows down due to low moisture availability
Solution Approach 1:
The patent adjusts chemical composition parameters by adding specific catalysts (0.01-2 wt%) to accelerate the moisture-curing reaction at low temperatures, and controls plasticizer/solvent content to balance viscosity reduction with moisture availability for curing
Solution Approach 2:
The patent introduces catalysts as intermediary substances that mediate between the limited moisture availability and the curing reaction, enabling adequate curing rates at low temperatures without requiring additional mixing equipment or two-component systems
3Productivity
If catalyst amount is increased to speed up curing at low temperatures, then curing rate is improved, but storage stability deteriorates
Solution Approach 1:
The patent optimizes the catalyst concentration parameter within a specific range (0.01-2 wt%) and balances it with plasticizer (2-25 wt%) and solvent (0-15 wt%) content to achieve sufficient curing rate at low temperatures while preventing premature reaction during storage, maintaining stability-performance balance
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 maintains low extrusion forces and rapid curing at temperatures as low as -10°C, providing excellent mechanical properties and adhesion, suitable for sealing and bonding applications without the need for additional mixing steps.
Implementation Method 1
the viscosity of such compositions is significantly increased, which leads to higher extrusion forces required for an application
Implementation Method 2
at least one catalyst C for the curing of polyurethane compositions
Implementation Method 3
between 5 and 30 wt.-% of at least one organic thixotropy agent TX
Implementation Method 4
a sufficient transport of atmospheric water required for curing into the fresh composition is significantly hindered
Data Source
AI summary
An one-part polyurethane composition, including: A) 15-75 wt.-% of at least one isocyanate-functional polyurethane polymer; B) 5-30 wt.-% of at least one organic thixotropy agent; C) 2-25 wt.-% of at least one plasticizer having viscosity of less than 500 mPa s, measured at 0° C. with cone-plate viscosimeter, shear rate 10 s−1, cone angle 1°, spindle 25-2, and cone tip-plate distance of 0.05 mm; D) 0-15 wt.-% of at least one solvent; E) 0-50 wt.-% of at least one filler; F) at least one catalyst for curing of polyurethane compositions; wherein isocyanate-functional polyurethane polymer has NCO content in range of 0.8%-2.5% by weight and is obtained from reaction of methylene diphenyl diisocyanate (MDI) and polyol in NCO/OH ratio of at least 3/1 and subsequent removal of non-reacted MDI; and polyol has viscosity, measured according to ASTM D4878-15 at 25° C., of less than 2000 mPa s; and isocyanate-functional polyurethane polymer has remaining content of MDI of at most 0.5% by weight.