Polyisocyanate Composition for Hydrolyzable Urethane Films
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Solution Overview
Problem
High-performance urethane compositions with excellent durability and hydrolysis resistance are not easily degradable, and existing polyisocyanate formulations with high isocyanate group content do not adequately address environmental degradability concerns.
Innovation Solution
A polyisocyanate composition derived from a diisocyanate and a polyester polyol with a controlled molar ratio of isocyanate to hydroxyl groups, high aliphatic diisocyanate content, and specific molecular weight and functional group characteristics, which is cured to form a film with improved appearance and hydrolyzability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-performance urethane composition is used to achieve excellent durability and hydrolysis resistance, then the material performance is improved, but the degradability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by using polyester polyols with specific molecular weights (1,000-4,000) and controlling the NCO/OH molar ratio (3.0-5.0), while limiting isocyanate group content to 1.0-5.9 mass%. These parameter adjustments maintain urethane performance while incorporating degradable ester bonds that can be hydrolyzed by microorganisms, thus resolving the contradiction between durability and degradability.
Solution Approach 2:
The invention creates a composite urethane structure combining stable urethane bonds (from isocyanate-hydroxyl reaction) with degradable ester bonds (from polyester polyol backbone). This composite structure allows the material to exhibit both excellent durability from the urethane linkage and degradability from the ester linkage, simultaneously satisfying both requirements.
2Strength
If the isocyanate group content is increased to improve crosslinking and performance, then the mechanical properties are improved, but the hydrolyzability and degradability deteriorate
Solution Approach 1:
The patent optimizes the isocyanate group content to a specific range (1.0-5.9 mass%) and controls the NCO/OH molar ratio (3.0-5.0) to achieve sufficient crosslinking for mechanical strength while maintaining adequate ester bond content for hydrolyzability. This balanced parameter selection resolves the contradiction between strength and degradability.
3Ease of manufacture
If a polyisocyanate with low isocyanate group content is used to improve degradability, then the environmental friendliness is improved, but the appearance and film formation quality deteriorate
Solution Approach 1:
The patent identifies a critical threshold range for isocyanate group content (1.0-5.9 mass%) and NCO/OH ratio (3.0-5.0) that simultaneously ensures good film appearance, proper curing, and high degradability. By maintaining parameters within this optimized range, the invention achieves all three goals without compromise.
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 resulting cured film exhibits excellent appearance and hydrolyzability, making it suitable for use in coatings and resins while addressing environmental degradability concerns.
Implementation Method 1
a resin grain form is subdivided by hydrolysis in a first stage
Data Source
AI summary
A polyisocyanate composition contains a polyisocyanate derived from a diisocyanate and a polyester polyol, wherein a molar ratio NCO/OH during a reaction between an isocyanate group of the diisocyanate and a hydroxy group of the polyester polyol is 3.0 or more, wherein the content of an aliphatic diisocyanate with respect to a total mass of the diisocyanate is 10 mass% or more and 100 mass% or less, wherein the polyisocyanate composition is substantially free of unreacted diisocyanates, wherein an isocyanate group content of the polyisocyanate composition with respect to a total mass of the polyisocyanate composition is 1.0 mass% or more and 5.9 mass% or less, and wherein the polyester polyol is composed of a dicarboxylic acid unit having 8 or fewer carbon atoms and a polyol unit.