Expanded Polymeric Material Process for Uniform Foam Morphology
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Solution Overview
Problem
Current foam injection molding technologies face challenges in preventing premature foaming and achieving uniform foam morphology, leading to heterogeneities and suboptimal properties in the final foam products.
Innovation Solution
A process involving the creation of a preform with a filling degree of 90% or less and thin structures, which is then inserted into a mold where blowing agents are solubilized under pressure and temperature, followed by abrupt pressure release for expansion, allowing for precise control over foam density and structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If foam injection molding is used to produce lightweight parts with expanded structures, then weight reduction and functional performance improvement are achieved, but premature foaming and heterogeneous foam morphology occur
Solution Approach 1:
The patent applies preliminary action by pre-mixing the blowing agent with the polymer material before injection molding, creating a homogeneous polymer-blowing agent mixture that prevents premature foaming during processing while enabling controlled expansion only when desired
Solution Approach 2:
The patent utilizes parameter changes by controlling the phase state of the blowing agent through temperature and pressure variations during processing, keeping it in a solubilized state during injection and molding, then triggering expansion through controlled pressure release or temperature change at the desired stage
2Reliability
If complex core-back operations are implemented to control pressure reduction, then foam formation at feed front is avoided, but device complexity and process difficulty increase
Solution Approach 1:
The patent extracts and eliminates the complex core-back operation from the foam injection molding process, achieving reliable foam formation control through simpler means such as optimized injection parameters, proper polymer-blowing agent mixing, and controlled pressure release without requiring additional complex mechanical systems
3Manufacturing precision
If post-injection solubilisation stage is used to melt early bubbles, then premature foam is eliminated, but production time increases and relative density under 0.5 cannot be achieved
Solution Approach 1:
The patent applies preliminary action by ensuring complete and homogeneous solubilization of the blowing agent in the polymer material before injection, preventing premature bubble formation entirely rather than requiring a post-injection solubilisation stage to melt early bubbles
Solution Approach 2:
The patent skips the lengthy post-injection solubilisation stage by achieving proper blowing agent solubilization during the injection and molding process itself, allowing direct progression to expansion and curing stages, thereby reducing production time and enabling achievement of relative density under 0.5
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 approach simplifies the extrusion process, eliminates the need for complex core-back operations, and enables the production of foamed products with relative densities lower than 0.5, achieving uniform and controlled foam morphology.
Implementation Method 1
a solubilisation step under pressure of the physical blowing agents in the preform
Implementation Method 2
an expansion step during which the pressure is released
Implementation Method 3
the solubilisation procedure of the physical blowing agents takes place under heat and under pressure
Data Source
AI summary
The present invention has as its object a process for making a product comprising a polymeric material expanded by using one or more blowing agents characterized in that said process comprises the following steps: ⋅ to make a preform of polymeric material with a filling degree equal to or less than 90% and thin structures having a thickness equal to or less than 3 mm, preferably equal to or less than 2 mm, ⋅ to make a mold including a cavity, said cavity having the shape of the desired product and dimensions equal to or greater than the overall volume of said preform, ⋅ to insert the preform into said cavity of the mold, ⋅ to solubilize under pressure one or more blowing agents in the preform within said mold cavity, ⋅ to release the pressure, and ⋅ to remove the product comprising the expanded polymeric material from the mold.