Polyester Granulate Acetaldehyde Reduction Underwater
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing polyester granulates with low acetaldehyde content are energy-intensive, require expensive nitrogen gas, and involve complex equipment and multiple processing stages, which are inefficient and costly, while also facing challenges in maintaining high viscosity and crystallinity for packaging applications.
Innovation Solution
A method involving underwater granulation of high-viscosity polyester melts, followed by centrifugal separation and treatment with rinsing air at controlled temperatures to reduce acetaldehyde content without the need for additional crystallization stages, using a device comprising an underwater granulator, centrifuge, and dealdehydisation container to produce granulates with low acetaldehyde levels and improved processing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If solid state polycondensation is used to increase intrinsic viscosity and reduce acetaldehyde content, then the acetaldehyde content is lowered and viscosity is increased, but the process requires expensive nitrogen gas, complex equipment, and multiple processing stages
Solution Approach 1:
The patent combines underwater granulation, centrifugal separation, and dealdehydisation into a single integrated device. The granulator includes both the granulation chamber and centrifugal separation mechanism, eliminating the need for separate crystallization equipment and reducing overall process complexity while achieving the same acetaldehyde reduction and viscosity enhancement effects
Solution Approach 2:
The patent extracts and eliminates the need for expensive nitrogen gas by using air as the processing medium. The dealdehydisation process operates in atmospheric conditions where acetaldehyde is removed through evaporation and air flow, replacing the nitrogen atmosphere required by conventional solid state polycondensation methods
2Strength
If solid state polycondensation is used to achieve high intrinsic viscosity, then the required strength is reached, but energy consumption increases and processing time is extended
Solution Approach 1:
The patent changes the processing parameters by conducting dealdehydisation at atmospheric pressure and moderate temperatures (50-150°C) rather than the high temperatures and pressures required by solid state polycondensation. The centrifugal force parameter is introduced to achieve rapid separation, reducing the time and energy required for processing while maintaining the necessary polymer strength through controlled acetaldehyde removal
3Productivity
If conventional granulation methods are used, then granulates are produced, but acetaldehyde content remains high and additional treatment stages are required
Solution Approach 1:
The patent merges granulation and dealdehydisation into a single simultaneous process. As granulates are formed underwater and separated centrifugally, hot air flows through the granulate bed to evaporate and remove acetaldehyde in real-time, eliminating the need for subsequent separate dealdehydisation treatment stages and maintaining high productivity
Solution Approach 2:
The patent establishes continuous acetaldehyde removal throughout the granulation process. Hot air continuously circulates through the granulate bed during formation and separation, maintaining constant low acetaldehyde levels without interruption or additional processing steps, thereby sustaining both high productivity and low harmful content
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 simplifies the process, reduces energy consumption, and maintains high-quality polyester granulates with low acetaldehyde content, allowing for efficient production of granulates suitable for food packaging with minimal acetaldehyde reformation and improved crystallinity, enabling processing at lower temperatures with reduced equipment complexity.
Implementation Method 1
a) the polyester melt strand is broken up under water at the highest possible temperature
Implementation Method 2
b) the accompanying water is separated, preferably by spinning, from the granulate with the least possible cooling of the granulate
Implementation Method 3
d) the granulate in the dealdehydisation container is treated using a flow of rinsing air with an intake temperature between 180° C. and 210° C.
Data Source
AI summary
The invention relates to a method for producing a granulate with a low acetaldehyde content and improved processing properties from a high-viscosity polyester melt, wherein the polyester melt strand is fragmented under water at the highest possible temperature, the accompanying water is separated from the granulate with the least possible cooling of the granulate, the low-water granulate obtained in this way is passed after removal of the water directly into a dealdehydisation container and the granulate in the dealdehydisation container is treated with a flow of rinsing air, plus a device for carrying out this method.