Polyisocyanate Blend Balancing Pot Life, Viscosity, and Compatibility
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Solution Overview
Problem
Existing polyisocyanate systems face challenges in achieving high chemical resistance, long pot life, and good incorporation characteristics while maintaining coating quality, particularly in high-quality coatings, with systems having a rather high OH content.
Innovation Solution
A polyisocyanate mixture comprising polyisocyanate and polyisocyanate, comprising a polyisocyanate mixture comprising a polyisocyanate mixture comprising a polyisocyanate mixture comprising a polyisocyanate mixture with specific isocyanurate and allophanate group contents, and optionally other structural units, to enhance stability and compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If biuret-containing polyisocyanates are used to achieve good compatibility, then compatibility is improved, but monomer stability is reduced
Solution Approach 1:
The patent uses a composite polyisocyanate system combining polyisocyanurate and polyallophanate components in specific ratios (30-70 wt% polyisocyanurate, 70-30 wt% polyallophanate). This composite approach leverages the stability of isocyanurate groups and the compatibility of allophanate groups, resolving the contradiction between monomer stability and compatibility that plagues pure biuret systems.
2Stability of the object's composition
If polyisocyanurates are used as crosslinking agents to achieve low viscosity and high solids content, then viscosity is reduced, but compatibility in the coating system is lowered
Solution Approach 1:
The patent merges polyisocyanurate and polyallophanate polyisocyanates into a single crosslinking system. The polyallophanate component specifically addresses the compatibility issue by providing good solubility and mixing characteristics, while the polyisocyanurate provides low viscosity and high solids content, thus combining the benefits of both materials.
3Adaptability or versatility
If high allophanate-containing polyisocyanate crosslinkers are used to achieve good compatibility, then compatibility is improved, but viscosity increases
Solution Approach 1:
The patent optimizes the allophanate group content to a specific range (15-60 mol%) rather than using high allophanate content exclusively. This parameter optimization, combined with the presence of polyisocyanurate groups, achieves the desired balance between compatibility and viscosity control.
Data Source
AI summary
The present invention relates to a polyisocyanate mixture containing at least one polyisocyanurate polyisocyanate and at least one polyallophanate polyisocyanate, wherein the polyisocyanate mixture has an amount of monomer diisocyanate of <0.10 wt. %, determined in accordance with DIN EN ISO 10283:2007-11 by gas chromatography using an internal standard, an isocyanurate group portion of ≥40 mol % to ≤85 mol %, determined by NMR spectroscopic analysis and based on the total amount of isocyanurate groups and allophanate groups of the polyisocyanate mixture, and an allophanate group portion of ≥15 mol % to ≤60 mol %, determined by NMR spectroscopic analysis and based on the total amount of isocyanurate groups and allophanate groups of the polyisocyanurate mixture.