Stabilizing HFO-1234ze Propellant in Polyurethane Foam
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Solution Overview
Problem
The challenge lies in extending the shelf life of gaseous olefinic propellants like HFO-1234ze, which are used in polyurethane foams, as they degrade quickly, affecting the performance and stability of the foam when stored for extended periods, especially when replacing HFC-134a, due to their inherent structure designed for atmospheric degradation.
Innovation Solution
A two-component polyurethane foam formulation is developed using high aromatic polyester polyols and a specific catalyst package, including a mild tertiary amine catalyst and a metal salt catalyst, to stabilize the propellant HFO-1234ze, maintaining foam properties within 20% of initial values after accelerated aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If HFO-1234ze propellant is used to replace HFC-134a, then ozone depletion and global warming potential are reduced, but shelf life is significantly shortened due to rapid degradation
Solution Approach 1:
A stabilization package consisting of antioxidants (such as BHT or vitamin E) and metal deactivators (such as EDTMP or DTPA) is introduced as intermediary substances to prevent degradation of the HFO-1234ze propellant. These stabilizers act as mediators between the propellant and degrading factors (oxygen, light, heat), significantly extending shelf life while maintaining the low environmental impact benefits of the HFO propellant
Solution Approach 2:
The storage conditions and formulation parameters are optimized to extend shelf life. This includes controlling storage temperature, adjusting the composition of the propellant blend, and modifying the stabilization package concentrations to achieve maximum stability. The patent describes how changing these parameters from conventional HFC formulations to HFO-specific parameters resolves the shelf life issue
2Duration of action of stationary object
If propellant is stored for extended periods, then availability for use is improved, but degradation occurs affecting foam performance and stability
Solution Approach 1:
Stabilizers and antioxidants are pre-added to the propellant formulation during manufacturing to prevent degradation before storage begins. This preliminary protective action ensures that the propellant maintains its performance characteristics throughout the intended storage period, allowing extended availability without compromising foam quality
Solution Approach 2:
The stabilization package serves as a protective intermediary layer between the HFO propellant and environmental degradation factors. By incorporating substances like vitamin E and EDTMP, the system creates a protective barrier that maintains propellant integrity during long-term storage, ensuring reliable foam performance
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 reformulated foam maintains physical properties within 20% of initial values for at least 12 months, ensuring stability and performance consistency, addressing the degradation issues of HFO-1234ze propellants.
Implementation Method 1
A two-component polyurethane foam formulation is developed using high aromatic polyester polyols and a specific catalyst package, including a mild tertiary amine catalyst and a metal salt catalyst, to stabilize the propellant HFO-1234ze
Implementation Method 2
trans-1-fluoro-3,3,3-trifluoroprop-1-ene (having a trade name of Solstice® This invention is particularly suited for extending the shelf life of the reactants used to synthesize polyurethane foams blown using the gaseous propellant
Data Source
Figure 1
AI summary
The invention described herein generally pertains to a composition and a method for improving the shelf life of a gaseous hydrofluoroolefin propellant, the improvement comprising at least the increased aromatic polyester polyol(s) in combination with a tertiary amine catalyst comprising at least two cyclohexyl rings and an aliphatic metal salt catalyst, the amine catalyst having less than 10% nitrogen on a weight basis.