PET Pellet Golf Ball Surface via Two-Stage Quenching and Crystallization
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Solution Overview
Problem
Existing methods for processing PET polymers into pellets struggle to achieve uniform crystallization with high crystallite content while maintaining pellet reactivity and decontamination properties, as excessive quenching can impede crystallization and lead to uneven heat distribution.
Innovation Solution
A two-stage post-treatment process is implemented, where pellets are quenched briefly with cold process water to create a golf ball-like surface structure, followed by a first post-treatment step at a slightly increased temperature for nucleus formation and a second step at a higher temperature for crystallization, with controlled gas supply and vibratory conveyor to ensure uniform heat application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pellets are extensively quenched with cold process water to create golf ball-like surface structure, then surface area and reactivity are improved, but crystallization is impeded and heat distribution becomes uneven
Solution Approach 1:
The quenching process is segmented into two distinct stages: first quenching to create the golf ball surface structure, then a second quenching phase that allows heat redistribution. This segmentation enables the surface to be frozen while the core retains enough heat to support uniform crystallization, resolving the contradiction between surface structure formation and crystallization uniformity.
Solution Approach 2:
The first quenching phase creates the desired golf ball surface structure preliminarily before the second quenching phase occurs. This preliminary action establishes the surface morphology needed for high surface area and reactivity, while the subsequent second phase ensures uniform heat distribution for crystallization.
2Productivity
If process water temperature is reduced below glass transition temperature to freeze pellets, then surface area increases and reactivity improves, but crystallization is prevented
Solution Approach 1:
The cooling process is divided into two sequential stages: first stage quenches the surface below glass transition temperature to create high surface area and golf ball structure, second stage allows controlled heat redistribution to enable uniform crystallization. This segmentation resolves the contradiction by timing the temperature effects appropriately.
Solution Approach 2:
The quenching process employs periodic action with two distinct temperature phases. The first phase creates the desired surface properties, the second phase restores heat distribution for crystallization. This periodic temperature variation allows both high reactivity surface structure and uniform crystallization to coexist.
3Object-generated harmful factors
If quenching is intensified to reduce by-product release, then acetaldehyde release decreases, but crystallization uniformity deteriorates
Solution Approach 1:
The quenching process is segmented into two phases: first phase intensifies cooling to minimize by-product release and create golf ball surface structure, second phase provides controlled heat redistribution to ensure uniform crystallization. This segmentation allows aggressive quenching for by-product reduction while maintaining crystallization uniformity through the second phase.
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 facilitates uniform crystallization with high crystallite content, enhances pellet reactivity, and reduces by-product release, improving handling and decontamination properties.
Implementation Method 1
the process water is driven at a temperature below the glass transition temperature of the PET polymers used in order to produce a golf ball-like surface structure on the PET pellets
Implementation Method 2
in a first post-treatment step a strong nuclei formation is initiated at only a slightly increased temperature over a shorter treatment time and then in a second post-treatment step the desired post-treatment result is achieved at a more increased temperature over a longer time
Implementation Method 3
with controlled gas supply and vibratory conveyor to ensure uniform heat application
Implementation Method 4
the pellets are treated by supplying gas of a first temperature, which is higher than the surface temperature of the pellets, for a first period of time in a first post-treatment chamber
Data Source
AI summary
The invention relates to a method for processing PET polymers in order to form PET pellets. A PET melt is granulated in an underwater granulator in order to form PET pellets, wherein the process water is driven at a temperature below the glass transition temperature of the used PETs in order to produce a golf ball-like surface structure on the pellets during the underwater granulation process. According to the invention, the pellets are separated from the super-cooled process water within a second or less and are subjected to an at least two-stage post-treatment process after the drying process, wherein the pellets are supplied with a gas of a first temperature which is higher than the surface temperature of the pellets for a first period of time, said gas being kept uniformly hot, in a first post-treatment chamber to form nuclei, and the pellets are treated in a second post-treatment chamber to crystallize at a second temperature which is higher than the first temperature over a second period of time which is a multiple of the first period of time.