HFO Blowing Agent Polyol Foam Stability
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Solution Overview
Problem
Conventional polyurethane and polyisocyanurate foam production using unsaturated halogenated hydrocarbons as blowing agents faces issues with storage stability and phase separation, leading to foam defects, particularly in large-scale industrial processes.
Innovation Solution
Incorporating a surfactant with a Hydrophile-Lipophile Balance (HLB) of less than 10, preferably less than 7, into the polyol component to enhance the miscibility of unsaturated chlorofluorohydrocarbon or fluorinated hydrocarbon blowing agents with polyol systems, preventing phase separation and improving storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If unsaturated halogenated hydrocarbons (HFO blowing agents) are used to achieve low gas-phase thermal conductivity and low GWP, then the foam insulation performance is improved, but the storage stability deteriorates due to insufficient miscibility and phase separation
Solution Approach 1:
The patent introduces surfactants as intermediary substances to mediate between the HFO blowing agent and the polyol component. These surfactants act as compatibility agents that reduce interfacial tension and prevent phase separation, enabling the HFO blowing agent to remain miscible in the polyol system during storage while maintaining its low GWP and thermal conductivity benefits.
Solution Approach 2:
The patent modifies the chemical composition parameters of the foamable mixture by adding specific surfactants with controlled HLB values (5-15). This parameter change transforms the system from one that undergoes phase separation to one that maintains homogeneous miscibility, thereby improving storage stability without sacrificing the performance advantages of HFO blowing agents.
2Manufacturing precision
If large amounts of HFO blowing agent are introduced to achieve optimal foam density and cell structure, then the foam quality is improved, but the miscibility with polyol system deteriorates leading to phase separation
Solution Approach 1:
Surfactants serve as intermediary agents that enable the polyol system to accommodate large quantities of HFO blowing agent. The surfactant molecules position themselves at the interface between the polar polyol and non-polar HFO, reducing interfacial tension and preventing the system from phase-separating even at high blowing agent concentrations, thus maintaining homogeneous miscibility.
Solution Approach 2:
The patent creates a composite system comprising polyol, HFO blowing agent, and surfactant. This composite formulation allows the components with different polarities to coexist homogeneously. The surfactant component acts as a compatibility modifier that enables the composite system to maintain stability at high HFO concentrations, achieving both optimal foam quality and miscibility.
3Stability of the object's composition
If conventional surfactants with high HLB values are used to improve miscibility, then storage stability is improved, but the foam stabilizer effectiveness deteriorates due to interference with silicon-containing foam stabilizers
Solution Approach 1:
The patent optimizes the HLB parameter of the surfactant within a specific range (5-15). This parameter optimization balances two competing requirements: sufficient hydrophilicity to maintain miscibility and storage stability, and limited hydrophilicity to avoid interfering with silicon-containing foam stabilizers. The controlled HLB value ensures both storage stability and reliable foam stabilizer performance.
Solution Approach 2:
The surfactant provides local stabilization at the interface between blowing agent and polyol without disrupting the bulk foam stabilizer action. By concentrating its effect at the molecular interface, the surfactant improves miscibility locally while leaving the silicon-containing foam stabilizer's foam-forming and stabilizing functions intact in the bulk system.
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 solution allows for the introduction of large amounts of HFO blowing agents without phase separation, even after 72 hours, and enables the use of high-silicone foam stabilizers without adverse effects, ensuring stable foam production and reducing defects.
Implementation Method 1
Incorporating a surfactant with a Hydrophile-Lipophile Balance (HLB) of less than 10, preferably less than 7, into the polyol component to enhance the miscibility of unsaturated chlorofluorohydrocarbon or fluorinated hydrocarbon blowing agents with polyol systems
Data Source
AI summary
The present invention relates to compositions which are suitable for producing polyurethane foams and contain at least one polyol component, at least one blowing agent, a catalyst which catalyzes the formation of a urethane or isocyanurate bond, a silicon-containing foam stabilizer and optionally further additives and optionally an isocyanate component, characterized in that they contain at least one unsaturated halogenated hydrocarbon as blowing agent and additionally at least one surfactant TD which does not have a silicon atom and has an HLB of less than 10, where the proportion of the sum of the surfactants TD in the composition is from 0.05 to 20 parts by mass per 100 parts by mass of polyol components, a process for producing polyurethane and polyisocyanurate foams, in particular rigid foams, starting out from these polyol compositions, the use of the foams, in particular as insulation material, and also the insulation materials themselves.