Low Acid Polyol Coating System with Lithium Catalyst
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Solution Overview
Problem
Existing polyurethane coating systems rely on tin-containing catalysts, which are toxic and pose environmental concerns, and often require long curing times, limiting their application in rapid coating processes such as automotive refinishing.
Innovation Solution
A coating agent system comprising a polyhydroxy group-containing compound with an acid number of not more than 9 mg KOH/g, a polyisocyanate-containing compound, and a catalyst containing lithium and at least one additional metal component like zinc, bismuth, or zirconium, allowing for separate or partial mixing of components to facilitate rapid curing without using toxic tin catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tin-containing catalysts are used in polyurethane coating systems, then the curing reaction can proceed, but the system becomes toxic and environmentally harmful
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst system by replacing tin-based catalysts with alternative metal catalysts (zinc, bismuth, zirconium, aluminum) combined with specific polyols having controlled acid numbers (0.5-9 mg KOH/g). This parameter change eliminates toxicity while maintaining curing capability through the synergistic interaction of the alternative catalyst metals with the polyhydroxy compounds.
Solution Approach 2:
The patent employs alternative metal catalysts that are less toxic and more environmentally friendly compared to tin catalysts. These alternative catalyst systems (zinc, bismuth, zirconium, aluminum compounds) serve as substitutes that achieve the same functional purpose without the harmful environmental persistence and toxicity associated with tin-based catalysts.
2Ease of manufacture
If conventional catalyst systems are used, then the coating can cure, but the curing time is prolonged
Solution Approach 1:
The patent optimizes the acid number parameter of the polyhydroxy group-containing compound to a specific range (0.5-9 mg KOH/g, preferably 0.5-5 mg KOH/g). This parameter optimization enhances the reactivity with polyisocyanate groups while working synergistically with the alternative metal catalysts, thereby reducing curing time compared to conventional systems without compromising the low-toxicity requirement.
Solution Approach 2:
The patent creates a composite catalyst system combining alternative metal compounds (zinc, bismuth, zirconium, or aluminum) with polyhydroxy group-containing compounds having specific acid numbers. This composite approach produces a synergistic effect that accelerates the curing reaction more effectively than either component alone, achieving rapid cure times suitable for automotive refinishing applications.
3Power
If polyols with higher acid numbers are used, then the catalyst activity may increase, but the system complexity and environmental impact worsen
Solution Approach 1:
The patent precisely controls the acid number parameter of the polyhydroxy group-containing compound within the range of 0.5-9 mg KOH/g (preferably 0.5-5 mg KOH/g). This parameter optimization achieves sufficient catalyst activity for rapid curing while maintaining environmental friendliness and simplifying the overall system formulation compared to high-acid-number polyols that would require additional neutralizing agents and complex stabilization systems.
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 system achieves faster curing times, particularly with lithium:bismuth and lithium:zinc molar ratios, ensuring rapid assembly stability and reducing environmental impact by avoiding tin-based catalysts, making it suitable for automotive refinishing and commercial vehicle coatings.
Implementation Method 1
a catalyst which contains lithium (Li) as the metal component and at least one further metal component selected from zinc (Zn), bismuth (Bi), zirconium (Zr) and/or aluminum (Al)
Implementation Method 2
the components (A) and (B) contained in the coating agent system according to the invention react with one another in the presence of the catalyst according to component (C) to form a polyurethane
Data Source
AI summary
The invention relates to a coating agent system comprising the components (A) to (C) and, if necessary, further components, wherein in a first option all the components (A) to (C) and, if necessary, also the further optional components are provided separately from each other, i.e. the individual components are not mixed together. In a second option of the coating agent system according to the invention, the aforementioned components can, by contrast, also be completely or at least in part mixed together. If the components are at mixed together at least in part, this means that, for example, component (C) is mixed with component (A), while component (B) is provided separately from this mixture of (A) and (C). If necessary however, component (B) can also be mixed with a partial quantity of component part (C). Furthermore, the mixtures of (A) and (C) and of (B) and (C) additionally contain at least one optional component, such as a solvent, for example. Component (A) comprises at least one polyhydroxy-group containing compound, which has an acid number of no more than 9 mg KOH/g of the corresponding polyhydroxy-group containing compound, and component (B) comprises at least one polyisocyanate containing compound. Component (C) on the other hand is a catalyst, which contains lithium as a metal component and at least one further metal component selected from zinc (Zn), bismuth (Bi), zirconium (Zr) and/or aluminium (Al). Hydroxyl-group containing compounds (B), coating additives (F), pigments (H) and/or solvents (J) for example, can be contained as further components in the coating agent system according to the invention.