Semi-crystalline Polyester Aerosol Container Stress Cracking
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Solution Overview
Problem
Conventional thermoplastic polyesters, such as PET, lack sufficient impact resistance and thermal resistance for the manufacture of aerosol containers, which can lead to issues like creep, leakage, and stress cracking under pressure, and existing solutions are costly and not optimally suited for polyester materials.
Innovation Solution
A semi-crystalline thermoplastic polyester is developed, comprising 1,4:3,6-dianhydrohexitol units, alicyclic diol units, and terephthalic acid units, with a specific molar ratio and reduced viscosity, eliminating the need for non-cyclic aliphatic diol units like ethylene glycol, enhancing glass transition temperature and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional PET is used for aerosol containers, then manufacturing simplicity is maintained, but impact resistance and thermal resistance are insufficient leading to creep and leakage
Solution Approach 1:
The patent uses a composite polyester material combining multiple components: polyethylene terephthalate (PET) as the base polymer, cyclohexanedimethanol (CHDM) as a diol modifier, and isosorbide as a renewable diol component. This composite approach creates a material that achieves both improved impact resistance and thermal resistance while maintaining manufacturing simplicity, resolving the contradiction between strength improvement and material complexity.
2Temperature
If isosorbide-based polyesters are used to improve thermal resistance, then glass transition temperature increases, but impact resistance becomes insufficient
Solution Approach 1:
The patent optimizes the compositional parameters of the polyester by controlling the molar ratios of different components: PET (40-70 parts), CHDM (10-40 parts), and isosorbide (10-40 parts). This parameter optimization allows the material to achieve both high glass transition temperature (improved thermal resistance) and sufficient impact resistance, resolving the contradiction between thermal and mechanical properties.
3Ease of manufacture
If PET is used for aerosol containers, then ease of manufacture is maintained, but stress cracking occurs under pressure
Solution Approach 1:
The patent introduces cyclohexanedimethanol (CHDM) as an intermediary modifier that bridges the base PET polymer and the renewable isosorbide component. CHDM acts as a compatibilizer that maintains the ease of manufacture of PET-based materials while incorporating isosorbide to improve stress cracking resistance and overall reliability under pressure, resolving the contradiction between manufacturing simplicity and reliability.
4Reliability
If existing solutions for improving polyester properties are implemented, then performance improves, but additional costs and process complexities are introduced
Solution Approach 1:
The patent merges multiple functions into a single polyester synthesis process: it simultaneously achieves improved thermal resistance (via isosorbide), impact resistance (via CHDM modification), and stress cracking resistance (via the combined polymer structure) in one consolidated polymerization process. This merging approach avoids the need for separate modification steps and reduces overall process complexity while achieving comprehensive performance improvement.
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 semi-crystalline thermoplastic polyester significantly reduces stress cracking and improves resistance to pressure and high temperatures, providing better mechanical properties for aerosol containers without the additional costs and complexities of existing solutions.
Implementation Method 1
enhancing glass transition temperature and thermal resistance
Implementation Method 2
semi-crystalline thermoplastic polyester
Data Source
AI summary
Use of a semi-crystalline thermoplastic polyester for producing an aerosol container, said polyester having at least one 1,4:3,6-dianhydrohexitol unit (A), at least one alicyclic diol unit (B) other than the 1,4:3,6-dianhydrohexitol units (A), and at least one terephthalic acid unit (C), wherein the molar ratio (A)/[(A)+(B)] is at least 0.05 and at most 0.30, said polyester being free of non-cyclic aliphatic diol units or comprising a molar amount of non-cyclic aliphatic diol units, relative to the totality of monomeric units in the polyester, of less than 5%, and with a reduced viscosity in solution (25°C; phenol (50 wt.%): ortho-dichlorobenzene (50 wt.%); 5 g/L of polyester) greater than 70 mL/g.