Two-Component Polyurethane Coating for Fast Drying and Low Viscosity
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Solution Overview
Problem
Existing liquid-applicable reactive polyurethane compositions used as coatings or paints have high viscosity, require significant volatile organic solvents, and have long drying times, making them difficult to apply and inefficient for industrial applications.
Innovation Solution
A two-component polyurethane composition comprising a first component with a specific ratio of polyacrylate polyol and polyester polyol, along with a second component of aliphatic polyisocyanate, which reduces viscosity, allows for easy application, and achieves a short drying time of under 4 hours while maintaining sufficient pendulum hardness and a gel time between 60 and 180 minutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If significant amount of volatile organic solvents are used to reduce viscosity, then workability is improved, but drying time increases and environmental harm increases
Solution Approach 1:
The patent changes the chemical composition parameters by using polyacrylate polyols with specific OH numbers (50-200 mg KOH/g) and controlling the polyol mixture ratio, which fundamentally alters the curing mechanism from solvent-evaporation-dependent to chemistry-dependent drying, achieving fast drying without excessive solvents
Solution Approach 2:
The patent creates a composite polyol system combining polyacrylate polyols and polyester polyols in specific ratios, where the polyacrylate component provides fast reaction with isocyanates for quick drying, while the polyester component maintains viscosity and workability, achieving both fast drying and good workability
2Loss of substance
If high solids content is used to reduce solvent amount, then VOC emissions are reduced, but viscosity increases making application difficult
Solution Approach 1:
The patent optimizes the OH number parameter of polyacrylate polyols (50-200 mg KOH/g) and controls the polyol mixture ratio to achieve the right balance between solids content and viscosity, enabling high solids content formulations that remain easily applicable
Solution Approach 2:
The patent uses polyester polyols as intermediaries that provide viscosity control and workability enhancement while the polyacrylate polyols drive the fast curing reaction, allowing the system to maintain both high solids content and good application properties
3Productivity
If fast drying time is achieved through formulation, then productivity increases, but gel time control becomes more difficult
Solution Approach 1:
The patent carefully controls the OH number parameter of polyacrylate polyols (50-200 mg KOH/g) and the stoichiometric ratio of polyols to isocyanates, which precisely controls the reaction kinetics to achieve fast drying while maintaining gel time within the acceptable range of 60-180 minutes
Solution Approach 2:
The patent establishes a feedback-controlled formulation system where the specific combination of polyacrylate polyol OH number, polyol mixture ratio, and isocyanate content is optimized to simultaneously achieve target drying time and gel time specifications, with adjustments made based on measured performance
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 provides a low-viscosity, easy-to-apply coating with a short drying time and stable storage properties, ensuring high pendulum hardness and controlled gel time, suitable for industrial applications.
Implementation Method 1
a first component containing at least one polyacrylate polyol PA, which is based on isobornyl (meth)acrylate, at least one polyester polyol PE with an OH number between 10 - 500 mg KOH/g, and a second component containing an aliphatic polyisocyanate B1
Implementation Method 2
wherein at least one polyacrylate polyol PA and that at least one polyester polyol PE together containing more than 99 wt% of the NCO-reactive groups, in particular the OH groups, of the first component
Data Source
AI summary
The invention relates to a composition consisting of a first component that contains at least one polyacrylate polylol based on isobornyl (meth) acrylate, and at least one polyester polyol with an OH number of 10 - 500 mg KOH/g, and a second component that contains an aliphatic polyisocyanate. The composition is particularly suitable as a protective coating for metal substrates. The composition has a short drying time, sufficient pendulum hardness and a gel time of between 60 and 180 minutes.