Liquid Polycaprolactone Co-Polyols for Ambient-Cure Polyurethanes
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Solution Overview
Problem
Existing polycaprolactone polyols are limited to solid form at ambient temperatures, restricting their use in room temperature polyurethane production processes, and current liquid alternatives compromise mechanical and durability properties.
Innovation Solution
A class of random copolymers of ε-caprolactone with alkyl substituents, maintaining liquid form at molecular weights above 800 g/mol, are developed, ensuring low viscosity and retention of mechanical and durability properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polycaprolactone polyols are used with molecular weight above 800 g/mol, then mechanical properties and durability are improved, but the polyols become solid at ambient temperature limiting their use in room temperature processes
Solution Approach 1:
The patent introduces alkyl substituents (methyl, ethyl, propyl, or butyl groups) at specific positions (4, 5, or 6) on the caprolactone ring structure. This chemical structural modification changes the physical properties of the polyol, specifically preventing crystallization and maintaining liquid state at ambient temperature while preserving the desired mechanical properties and durability associated with higher molecular weight polycaprolactone polyols
Solution Approach 2:
The invention creates a composite molecular structure by incorporating substituted caprolactone units into the polyol chain alongside unsubstituted caprolactone units. This compositional approach allows the material to exhibit both the liquid characteristics needed for room temperature processing and the mechanical performance associated with polycaprolactone polyols
2Ease of operation
If copolymerisation with chemically different monomers is used to produce liquid polycaprolactone polyols, then processability at ambient temperature is improved, but mechanical performance and durability are compromised
Solution Approach 1:
Instead of using chemically different monomers throughout the polymer chain, the patent applies alkyl substituents at specific local positions (4, 5, or 6) on individual caprolactone rings. This localized modification maintains the overall polycaprolactone chemical structure and its associated mechanical properties while locally altering the physical state to liquid at ambient temperature
3Ease of operation
If low molecular weight caprolactone polyols are used to maintain liquid form, then ease of operation is improved, but the materials become heavily cross-linked and rigid
Solution Approach 1:
The patent changes the chemical structure by introducing alkyl substituents on the caprolactone rings, which fundamentally alters the physical properties without requiring reduction in molecular weight. This allows the use of higher molecular weight polyols (maintaining flexibility and resilience) while still achieving liquid state at ambient temperature through the steric and electronic effects of the alkyl groups
Data Source
AI summary
The present disclosure provides a polycaprolactone co-polyol composition that includes a reaction product of one or more hydroxyl-functional organic compound with ε-caprolactone and one or more ε-caprolactone with more than one alkyl substituent, wherein each of the alkyl substituents is independently selected, the one or more hydroxy-functional organic compound is present in the range of about 5.0 wt % to about 95.0 wt %, the ε-caprolactone is present in the range of about 5.0 wt % to about 95.0 wt %, the one or more ε-caprolactone with more than one alkyl substituent is present in the range of about 5.0 wt % to about 95.0 wt %, and the polycaprolactone co-polyol has an average molecular weight of about 500 g/mol to about 10,000 g/mol. The disclosure further provides methods of making the polycaprolactone co-polyol compositions, compositions including the same, and methods of making and using the same.