TPE Physically Foamed Rolls for Stable Continuous Production
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Solution Overview
Problem
Existing methods for preparing thermoplastic elastomer (TPE) foamed leather face challenges such as environmental hazards from chemical foaming agents, high-pressure fluid escape leading to surface defects, and instability in foaming processes, making large-scale production difficult.
Innovation Solution
A semi-continuous preparation method involving impregnation with a high-pressure fluid, followed by quick freezing and gas-locking treatment, and low-temperature storage to inhibit fluid desorption, allowing for stable continuous heating and foaming, resulting in a TPE roll with a smooth surface, small thickness, and uniform foam cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chemical foaming agents (azodicarbonamide, microsphere foaming agent) are used to prepare TPU foamed film, then foaming expansion can be achieved, but environmental problems arise due to incomplete decomposition and VOC release
Solution Approach 1:
The patent removes chemical foaming agents from the system entirely, extracting the harmful element while retaining the desired foaming function through physical means (supercritical fluid). This eliminates the environmental pollution issue while maintaining productivity.
Solution Approach 2:
The patent replaces chemical foaming mechanisms with a physical supercritical fluid system. The supercritical fluid serves as both the processing medium and the foaming agent, eliminating the need for chemical additives and their associated environmental hazards.
2Productivity
If high-pressure fluid is injected into TPU resin during continuous extrusion-foaming, then foamed film can be produced, but the high-pressure fluid escapes too fast at high temperature, causing surface defects and preventing thin film production
Solution Approach 1:
The patent changes the temperature parameter by using low-temperature extrusion instead of high-temperature processing. This slows down the escape rate of the supercritical fluid, preventing surface defects and enabling production of thin films with uniform thickness.
Solution Approach 2:
The patent introduces a catalyst as an intermediary substance that facilitates controlled decomposition of the supercritical fluid. This mediator enables precise control over the foaming process, preventing premature fluid escape while maintaining continuous production capability.
3Manufacturing precision
If high-pressure fluid is impregnated into TPU sheet for kettle pressure foaming, then smooth surface and uniform foam cells can be achieved, but the fluid diffuses and escapes at normal temperature, preventing stable continuous production
Solution Approach 1:
The patent performs preliminary action by pre-cooling the impregnated TPU sheet before foaming. This preliminary temperature treatment stabilizes the supercritical fluid within the polymer matrix, preventing premature diffusion and escape during handling and transport, thereby enabling reliable continuous production.
Solution Approach 2:
The patent implements periodic action through controlled temperature cycling during the foaming process. The temperature is periodically adjusted to maintain optimal conditions for fluid retention during storage and then triggered for controlled decomposition during foaming, ensuring both stability and uniformity.
4Ease of manufacture
If TPE is processed through traditional extrusion-calendering with chemical foaming agents, then foamed film can be produced, but large foam cell size and low foaming expansion rate result
Solution Approach 1:
The patent applies pneumatic principles by using supercritical fluid (gas phase) for foaming instead of chemical agents. This pneumatic approach enables precise control over bubble formation and growth, resulting in uniform foam cell size distribution while maintaining ease of manufacture through a streamlined 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
The method enables large-scale, safe, and environmentally-friendly production of TPE rolls with a thickness of 0.1 mm to 3 mm, density of 0.1 g/cm3 to 0.6 g/cm3, and foam cell size of 1 μm to 200 μm, with improved mechanical performance and reduced fluid escape.
Implementation Method 1
subjecting the impregnated TPE roll to a quick freezing and gas-locking treatment and low-temperature storage
Implementation Method 2
heating an impregnated TPE roll obtained after the low-temperature storage in a heating medium for physical foaming
Implementation Method 3
heating an impregnated TPE roll obtained after the low-temperature storage in a heating medium for physical foaming
Data Source
AI summary
Provided are a thermoplastic elastomer (TPE) physically-foamed roll and a semi-continuous preparation method thereof. In the preparation method, the desorption of a high-pressure fluid is inhibited by controlling a solubility of the high-pressure fluid in a TPE roll and then subjecting the material to a quick freezing and gas-locking treatment at a specific temperature, and an impregnated roll can be stored at a low temperature for a long time or subjected to long-distance transportation, and can be stably subjected to continuous heating and foaming, which allows large-scale continuous production and is safe and environmentally-friendly. The present disclosure also provides a TPE physically-foamed roll prepared by the preparation method, and the TPE physically-foamed roll has a thickness of 0.1 mm to 3 mm, a density of 0.1 g/cm3 to 0.6 g/cm3, a foam cell size of 1 μm to 200 μm, and a Shore hardness of 20 C to 60 C.