Polyester Container Transparency and Heat Resistance via Isosorbide
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Solution Overview
Problem
Polyethylene terephthalate (PET) resin-based containers face challenges with low transparency due to high crystallinity and poor heat resistance, which limits their use in applications requiring high heat resistance and thick thickness, such as hot fill bottles, and introducing isosorbide to improve heat resistance reduces crystallization rate and regularity of polymer chains.
Innovation Solution
A polyester container is developed using a resin polymerized with terephthalic acid, isosorbide, and ethylene glycol, with specific mole percentages of diol moieties from isosorbide and diethylene glycol to achieve an alternating structure that maintains high transparency and heat resistance, allowing for thick wall thickness without haze.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If isosorbide content is increased to improve heat resistance, then glass transition temperature increases and mechanical strength improves, but polymer chain regularity decreases and crystallization rate decreases
Solution Approach 1:
The patent optimizes the molar ratio parameters of isosorbide (6-12 mol%) and diethylene glycol (2-5 mol%) in the polyester resin to achieve the desired balance between heat resistance and crystallization rate. By precisely controlling these compositional parameters, the resin attains sufficient glass transition temperature while maintaining adequate crystallization capability for bottle drawing.
Solution Approach 2:
The patent creates a composite polyester resin system combining multiple diol components (isosorbide, ethylene glycol, and diethylene glycol) to achieve synergistic effects. This composite approach allows the resin to simultaneously exhibit improved heat resistance from isosorbide and maintained processability from the other diol components, resolving the contradiction between heat resistance enhancement and crystallization rate preservation.
2Temperature
If isosorbide content exceeds certain level to improve heat resistance, then glass transition temperature increases, but resin cannot function as crystalline resin and drawing becomes impossible
Solution Approach 1:
The patent establishes specific parameter ranges for isosorbide content (6-12 mol%) and diethylene glycol content (2-5 mol%) to maintain the resin's crystalline character while achieving improved heat resistance. These parameter constraints ensure the resin remains drawable on existing PET equipment, preventing the loss of processability that would occur with excessive isosorbide addition.
Solution Approach 2:
The patent introduces diethylene glycol as an intermediary component that mediates between the heat resistance enhancement provided by isosorbide and the crystallization capability required for processability. This intermediary component helps maintain polymer chain regularity and crystallization rate, enabling the resin to function as a crystalline resin that can be drawn into bottles using conventional PET processing equipment.
3Strength
If PET resin is used for thick thickness applications, then structural strength is sufficient, but transparency is lowered due to high crystallinity
Solution Approach 1:
The patent modifies the compositional parameters of the polyester resin by incorporating isosorbide (6-12 mol%) and diethylene glycol (2-5 mol%), which changes the crystallization behavior and crystal structure of the resin. This parameter change allows the resin to maintain structural strength for thick-walled applications while reducing excessive crystallinity that would otherwise cause haze and reduce transparency.
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 polyester container exhibits high transparency and excellent heat resistance, enabling its use in thick-walled applications like hot fill jars and high-pressure vessels, while maintaining processability on existing PET processing equipment.
Implementation Method 1
a polyester resin that is polymerized with a dicarboxylic acid including terephthalic acid or a derivative thereof and a diol including isosorbide and ethylene glycol
Implementation Method 2
a melting point exists during the first scan through a differential scanning calorimetry (DSC)
Data Source
AI summary
The present invention relates to a polyester container. The polyester container is formed from a polyester resin containing a particular content of diol moieties derived from isosorbide and diethylene glycol, and thus can show high transparency in spite of a great wall thickness thereof.