Sprayable Polyurethane Coating Viscosity Control
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Solution Overview
Problem
Existing protective coatings for large industrial containers, such as frac tanks, face issues with cracking in cold climates and are not sprayable due to high solvent content, while requiring chemical resistance and high reactivity.
Innovation Solution
A sprayable polyurethane-based reaction system comprising a first and second component, both with specific butylene oxide-propylene oxide copolymer polyols and isocyanates, which are mixed immediately before application to provide a coating with high tensile strength and chemical resistance, minimizing solvent use and optimizing reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy solids based system is used to form protective coating, then chemical resistance is improved, but cracking occurs especially in colder climates
Solution Approach 1:
The patent changes the chemical composition parameters by using polyol component (including polyether polyol and polyester polyol) and isocyanate component to form polyurethane coating instead of epoxy coating, maintaining chemical resistance while improving flexibility and crack resistance through different polymer chemistry
Solution Approach 2:
The patent uses a composite polyol system combining polyether polyol and polyester polyol in specific ratios, creating a composite coating material that integrates the chemical resistance of polyester with the flexibility and cold-weather performance of polyether
2Reliability
If butadiene containing formulations are used to reduce solvent content, then chemical resistance is improved, but sprayability is reduced
Solution Approach 1:
The patent changes the viscosity parameters by selecting specific molecular weight ranges for polyol (500-5000 cP) and isocyanate components, and controlling the NCO content (15-30%), achieving optimal sprayability while maintaining high solids content and chemical resistance
Solution Approach 2:
The patent applies different molecular weight polyols with specific hydroxyl functionalities (1.5-3.5) to achieve local optimization of viscosity and sprayability characteristics while maintaining overall coating performance
3Quantity of substance
If high solids content formulation is used, then solvent content is minimized, but viscosity increases reducing sprayability
Solution Approach 1:
The patent optimizes the physical parameters by selecting polyol molecular weight (500-5000 cP), hydroxyl functionality (1.5-3.5), and isocyanate NCO content (15-30%), achieving high solids content (90-100%) while maintaining sprayable viscosity through balanced component selection
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 a protective coating with tensile strength of at least 1500 psi and percent elongation at break of at least 400, maintaining chemical resistance in abrasive and corrosive environments, including exposure to acids and fuels, without the need for solvents, ensuring durability and applicability on large surfaces.
Implementation Method 1
a first component which is a reaction product of a polyol component and an isocyanate component... a reaction product of the first component and the second component has a tensile strength of at least 1500 psi and a percent elongation at break of at least 400
Data Source
AI summary
A sprayable polyurethane based reaction system for forming a protective coating in industrial containers includes a first component and a second component, each having a viscosity less than 1500 cP at 25° C. A difference between the viscosities of the first component and the second component within a temperature range of 60° C. and 80° C. is from −150 cP to 150 cP. The first component is a reaction product of a polyol component that includes a first butylene oxide propylene oxide copolymer polyol having a polyoxybutylene content of at least 50 wt % and an isocyanate component that includes at least one polyisocyanate. The second component has a second butylene oxide propylene oxide copolymer polyol having a polyoxybutylene content of at least 50 wt %. At least one selected from a group of the polyol component and the second component includes a primary hydroxyl containing polyol.