Polyamide Granulation on Metal Belt via Viscosity Control
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Solution Overview
Problem
There is a need for a method to granulate polyamides with low melt viscosity that can produce stable granules with minimal shape variation and prevent cobwebbing, as existing methods struggle with adhesion issues and high heat loss.
Innovation Solution
Control the melt viscosity and terminal amino group concentration of polyamides within specific ranges, then drop the molten polyamides onto a metal belt for solidification, using a metal belt with a normal pressure type or applied pressure type melt polymerization vessel or single-screw/twin-screw extruder to achieve consistent granule formation without special removal means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a low-viscosity polyamide is granulated by dropping onto a metal cooling belt, then granulation is feasible, but the granules adhere strongly to the belt causing damage and cobwebbing
Solution Approach 1:
The patent controls the terminal amino group concentration within 5-70 μeq/g and melt viscosity within 3-200 Pa·s to optimize the balance between granulation feasibility and granule removal. These parameter ranges prevent excessive adhesion while maintaining droplet formation capability.
Solution Approach 2:
The patent introduces a cooling belt surface temperature parameter as an intermediary control mechanism. By maintaining the belt temperature below the polyamide melting point but above ambient temperature, the system achieves controlled solidification that reduces adhesion strength while preventing premature solidification in the air.
2Reliability
If the die temperature is increased to prevent resin burning, then granulation stability improves, but heat loss increases and energy consumption rises
Solution Approach 1:
The patent employs continuous dropping of molten polyamide onto the cooling belt, eliminating interruptions and maintaining steady-state heat transfer. This continuous process reduces thermal fluctuations and minimizes energy loss compared to batch processing.
Solution Approach 2:
The patent utilizes the phase transition from liquid to solid at the cooling belt interface to rapidly solidify the polyamide droplets. This phase change occurs locally at the belt surface, allowing the bulk material to remain molten at lower temperatures, thereby reducing overall heat loss.
3Shape
If the terminal amino group concentration is increased to improve granule formation, then droplet formation improves, but adhesion to the metal belt increases causing cobwebbing
Solution Approach 1:
The patent precisely controls the terminal amino group concentration within 5-70 μeq/g to achieve optimal droplet formation while preventing excessive adhesion. This parameter optimization balances surface properties for good shape formation without creating harmful cobwebbing effects.
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 stable granulation of polyamides with low viscosity, producing granules with consistent particle size and shape, reducing cobwebbing and adhesion issues, and enabling efficient removal from the metal belt.
Implementation Method 1
dropping the resultant onto a metal belt for solidification
Implementation Method 2
melting polyamide by heating
Data Source
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AI summary
The present invention provides a method for granulating a polyamide or a polyamide composition, whereby it becomes possible to granulate even a polyamide that has such a melt viscosity that the polyamide cannot be pelletized into a strand-like shape easily. In the present invention, a polyamide, whose melt viscosity at glass transition temperature + 160°C and a shear rate of 100s-1 is 3Pa·s to 200Pa·s and whose terminal amino group concentration is 5µeq/g to 70µeq/g, is melted by heating to a range of glass transition temperature + 160°C to glass transition temperature + 180°C of the polyamide, and then is solidified by dropping the molten polyamide in the form of granules onto a metallic belt, thereby producing granules.