PDI Polyisocyanate Coatings for Rapid Drying
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Solution Overview
Problem
Current hydrophilically modified polyisocyanates, derived from 1,6-diisocyanatohexane (HDI), delay paint drying due to retained solvent water, which is undesirable for applications like wood and vehicle coatings requiring rapid drying, and there is a lack of specific descriptions for water-dispersible polyisocyanate mixtures based on 1,5-diisocyanatopentane (PDI).
Innovation Solution
A polyisocyanate composition comprising a polyisocyanate component based on 1,5-diisocyanatopentane and an emulsifier component, including ionic and/or nonionic emulsifiers, which stabilizes the polyisocyanates in aqueous emulsions, allowing for faster drying and maintaining optical properties comparable to HDI-based coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydrophilic HDI polyisocyanates are used as crosslinking components in aqueous paint systems, then the paint can be stirred finely and homogeneously without high shearing forces, but the drying of the paint is significantly delayed due to retained solvent water
Solution Approach 1:
The patent changes the chemical structure parameter from HDI (1,6-diisocyanatohexane) to PDI (1,5-diisocyanatopentane), altering the molecular chain length and hydrophilicity. This structural parameter change results in reduced water retention in the film while maintaining good dispersibility in aqueous systems, thus resolving the contradiction between mixing ease and drying speed
Solution Approach 2:
The patent creates a new polyisocyanate composition based on PDI that replicates the beneficial dispersibility properties of HDI-based polyisocyanates while eliminating the detrimental water retention effect. The PDI-based composition serves as an alternative copy that improves upon the original HDI system's drying characteristics
2Object-affected harmful factors
If hydrophilic-modified polyisocyanates are used to enable water-based formulations, then environmental friendliness is improved, but drying speed deteriorates due to water retention
Solution Approach 1:
The patent modifies the hydrophilicity parameter of the polyisocyanate by using PDI instead of HDI as the base structure. This parameter change allows the material to maintain water-based formulation compatibility (environmental friendliness) while reducing excessive water retention, thereby improving drying speed without sacrificing environmental benefits
3Speed
If rapid drying is required for applications like wood/furniture coating or car repair, then drying speed is improved, but the use of conventional hydrophilic polyisocyanates results in poor optical properties
Solution Approach 1:
The patent changes the molecular structure parameter from HDI to PDI, which alters the hydrophilicity and film formation characteristics. This parameter change enables rapid drying (improving speed) while the PDI-based polyisocyanate maintains compatibility with aqueous binders to achieve excellent optical properties such as gloss and transparency (addressing illumination intensity)
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 polyisocyanate composition results in coatings that dry significantly faster than those using HDI-based hydrophilic polyisocyanates while maintaining excellent optical properties and water resistance, making it suitable for various applications without the need for high shearing forces during dispersion.
Implementation Method 1
an emulsifier component B), wherein the emulsifier component B) consists of at least one ionic and/or nonionic emulsifier, wherein the polyisocyanate component A) can be stirred finely and homogeneously into aqueous paint binder dispersions without the use of high shearing forces
Data Source
AI summary
The invention relates to a polyisocyanate composition based on 1,5-diisocyanatopentane, to a method for the production thereof and to the use thereof for producing polyurethane plastics. The invention also relates to a coating agent containing the polyisocyanate composition and to the coating obtained from the coating agent.