Polyurea Primer Curing Below 0°C Without Bubbles
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Solution Overview
Problem
Existing primers for industrial and carpark floors face challenges in curing below 5 degrees Celsius, leading to bubble formation and impaired adhesion and waterproofing, while epoxy-based primers lack flexibility and urethane-based primers require high NCO-content, which also leads to bubble formation.
Innovation Solution
A polyurea composition comprising isocyanate-functional polyurethane polymer, blocked amine, silane, and aminosilane, with specific ratios and components, allowing curing below 0°C without bubble formation and ensuring adhesion to concrete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy-based primers are used to achieve adhesion to concrete substrate, then adhesion is improved, but flexibility is reduced and crack bridging capability is limited
Solution Approach 1:
The patent combines epoxy resin and polyurethane components into a single primer composition. The epoxy component provides strong adhesion to concrete substrate, while the polyurethane component provides flexibility and crack bridging capability. This merging of two different polymer systems allows the primer to simultaneously achieve both strong adhesion and flexibility, resolving the technical contradiction between these two properties.
2Strength
If epoxy-based primers are used to ensure adhesion, then bonding strength is improved, but curing performance at low temperatures below 5 degrees Celsius deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the primer by incorporating polyurethane components with specific molecular weights and flexibility characteristics. This parameter change allows the primer to maintain epoxy-like adhesion strength while gaining the ability to cure effectively at low temperatures below 5°C, as the polyurethane component has lower glass transition temperature and remains flexible in cold conditions.
3Reliability
If urethane-based primers with high NCO-content are used to improve low-temperature curing, then curing performance is improved, but bubble formation occurs impairing adhesion and waterproofing
Solution Approach 1:
The patent uses different polyurethane components with different molecular weights (600-10,000 g/mol) and flexibility characteristics in specific proportions. The lower molecular weight polyurethane provides flexibility and prevents bubble formation, while the higher molecular weight polyurethane ensures adequate adhesion. This local differentiation of component properties within the primer composition allows low-temperature curing without bubble formation.
4Reliability
If a primer layer is applied to achieve adhesion and waterproofing, then protection is improved, but applicability by roller at low temperatures below 0 degrees Celsius deteriorates
Solution Approach 1:
The patent formulates the primer with polyurethane components that maintain dynamic flexibility at low temperatures. The polyurethane chains remain mobile and flexible below 0°C, allowing the primer to be easily applied by roller despite the cold conditions. This dynamic flexibility ensures both ease of application and subsequent adhesion performance, resolving the contradiction between protectiveness and applicability at low temperatures.
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 polyurea composition cures effectively at low temperatures, providing excellent adhesion and waterproofing without bubbles, enabling easy roller application and rapid curing within 6 hours at -10°C.
Implementation Method 1
at least one blocked amine BA which has a blocked, hydrolytically activatable amino group
Implementation Method 2
at least one silane S1 selected from the list consisting of isocyanatosilanes S1-1 and epoxy silanes S1-2; at least one aminosilane S2
Implementation Method 3
a first component A comprising; at least one isocyanate-functional polyurethane polymer P1; a second component B comprising; at least one blocked amine BA
Data Source
AI summary
A polyurea composition includes a first component A with at least one isocyanate-functional polyurethane polymer P1 and a second component B including a blocked amine BA and preferably a polyamine PA having a molecular weight in the range from 60 to 500 g/mol. The polyurea composition further includes a silane S1 selected from the list consisting of isocyanatosilanes S1-1 and epoxy silanes S1-2 as well as an aminosilane S2. The polyurea composition is notable for being suitable for providing a primer system for floor coating system which ensures sufficient adhesion to concrete, can cure at temperatures below 0° C., preferably below −10° C., without bubble formation and ensures sufficient applicability to be roller applied at temperatures below 0° C.