One Component Polyurethane Allophanate Coatings with Reactive Reducer
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Solution Overview
Problem
Polyurethane-forming compositions with tertiary amine catalysts are unstable and have short pot-life when used in clear-coat applications due to viscosity issues and acidity differences between clear-coat and basecoat, lacking a stable one-component cross-linking approach.
Innovation Solution
Crosslinking polyuretdione resins with neutralized polyols in the presence of a reactive reducer containing a reducing agent and a tertiary amine catalyst, which reduces viscosity and neutralizes the basecoat, allowing for improved clear-coat curing and extended storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tertiary amine catalyst is added to the clear-coat to catalyze the reaction, then the clear-coat curing is improved, but the shelf-life is reduced due to instability
Solution Approach 1:
The patent applies preliminary action by incorporating the tertiary amine catalyst into the clear-coat formulation in advance, but designing it to remain dormant or stable during storage. The catalyst is pre-positioned in the system but activated only when needed during the clear-coat application and curing process, rather than being added at the moment of use. This allows the catalyst to be present for curing while maintaining stability during shelf storage.
2Reliability
If an excess amount of catalyst is added to the clear-coat to neutralize the acidic basecoat, then the basecoat neutralization is improved, but the pot-life is reduced to very short duration
Solution Approach 1:
The patent uses preliminary action by pre-incorporating the catalyst into the clear-coat formulation with the understanding that it will perform the neutralization function when applied over the basecoat. The catalyst is positioned in advance in the clear-coat, and the system is designed to allow sufficient pot-life for mixing and application before the neutralization and curing processes begin.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the concentration and type of tertiary amine catalyst used. Instead of using excess catalyst that would cause immediate reaction and short pot-life, the formulation uses an optimized amount that provides sufficient neutralization capability while maintaining acceptable pot-life for practical application. The specific parameters of the catalyst (molecular weight, structure, basicity) are selected to balance reactivity with stability.
3Reliability
If polyuretdiones and polyols are combined in the presence of tertiary amine catalysts, then the cross-linking reaction is improved, but the system stability is reduced
Solution Approach 1:
The patent applies segmentation by separating the polyuretdione resin and polyol components into distinct parts that are mixed only when needed for application. The clear-coat formulation contains the polyuretdione resin with the tertiary amine catalyst pre-incorporated, while the polyol is either separate or added at the time of use. This segmentation prevents premature reaction and maintains system stability during storage, while enabling complete cross-linking when the components are combined for application.
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 a stable one-component clear-coat composition with extended storage stability and improved curing properties, suitable for coatings, adhesives, and sealants, by effectively addressing the instability and short pot-life issues in polyurethane systems.
Implementation Method 1
a reactive reducer containing a reducing agent and a tertiary amine catalyst
Implementation Method 2
the reactive reducer has reduced the viscosity of the formulation to appropriate levels
Data Source
AI summary
The present invention provides an allophanate polymer system made by a method comprising combining a neutralized polyol with a polyuretdione resin in the presence of a reactive reducer comprising a reducing agent and a tertiary amine catalyst to produce a clear-coat, and contacting the clear-coat with a basecoat comprising a tertiary amine catalyst. The reaction between the polyol and the polyuretdione will proceed after the reactive reducer reduces the viscosity of the one component clear-coat formulation to appropriate levels. The inventive allophanate polymer system is particularly applicable in providing coatings, adhesives, castings, composites, and sealants with good performance.