Polyisocyanurate Foam Panel Injection Under Reduced Pressure
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Solution Overview
Problem
The discontinuous process for producing polyisocyanurate sandwich panels faces challenges with poor flow and bonding due to high applied densities and viscous aromatic polyesters, resulting in inadequate filling and mechanical/thermal properties, while maintaining fire retardant performance.
Innovation Solution
Incorporating a proper amount of aromatic polyester polyol in the polyol formulation with a flame retardant and injecting the mixture under reduced atmospheric pressure into a closed mold cavity, ensuring an isocyanate index greater than 250, to enhance filling and bonding while maintaining fire retardant properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high index polyisocyanurate formulations with viscous aromatic polyesters are used, then fire retardant properties are improved, but flow and filling ability deteriorate
Solution Approach 1:
The patent changes the pressure parameter from atmospheric to reduced pressure (vacuum or sub-atmospheric) to improve the flow and filling ability of high index polyisocyanurate formulations while maintaining their fire retardant properties
Solution Approach 2:
The patent introduces a vacuum or sub-atmospheric pressure system as an intermediary mechanism to facilitate the injection and filling process, enabling viscous aromatic polyester-based formulations to flow properly without compromising fire safety
2Loss of substance
If reduced pressure is applied to improve filling, then material usage is reduced, but bonding strength may deteriorate
Solution Approach 1:
The patent employs feedback control through monitoring of injection pressure, temperature, and reaction progress to ensure adequate bonding strength is achieved while minimizing material usage under reduced pressure conditions
Solution Approach 2:
The patent adjusts multiple parameters including temperature, pressure, and formulation composition to optimize the balance between material efficiency and bonding strength in the discontinuous process
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
This method allows for improved filling of the mold cavity, reduced pressure on the mold, and enhanced bonding to facers, achieving fire retardant performance comparable to continuous processes with reduced material usage and costs.
Implementation Method 1
reacting a stoichiometric excess of polyisocyanate with a polyol or polyol mixture
Implementation Method 2
the presence of isocyanurate rings, formed by the cyclotrimerisation reaction of isocyanates
Implementation Method 3
containing a low-conductivity gas, such as a hydrofluorocarbon (HFC) or hydrocarbon, in the cells
Data Source
AI summary
The present invention discloses the production of panels by a discontinuous process. The panels are produced by injecting a polyisocyanurate foam forming composition into the mold cavity at reduced pressure. The combination of certain polyisocyanurate foam forming formulation and the reduced pressure in the mold cavity allows production of and resulting sandwich panels in a discontinuous process where the produced panels are characterized by improved fire resistance.