Cyclobutanediol Polyester Sheets for Dry-Free Thermoforming
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Solution Overview
Problem
Current polyester compositions used in sheets and films, such as poly(1,4-cyclohexylenedimethylene terephthalate) and polycarbonate, face challenges in crystallization rates, impact strength, glass transition temperature, and processability, making them difficult to thermoform without pre-drying and limiting their industrial application.
Innovation Solution
A polyester composition comprising terephthalic acid, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanedimethanol with specific mole percentages and inherent viscosity ranges, allowing for thermoforming without pre-drying and maintaining properties like hydrolytic stability, chemical resistance, and processability on standard equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PCT crystallizes rapidly upon cooling from the melt, then high crystallization rate is achieved, but it becomes very difficult to form amorphous articles by extrusion, injection molding, and similar methods
Solution Approach 1:
The patent modifies the crystallization parameters of PCT by incorporating copolymer components (isophthalic acid and/or ethylene glycol) that alter the crystallization kinetics, enabling slower crystallization rates that allow amorphous article formation while maintaining manufacturing efficiency
Solution Approach 2:
The invention creates a composite polyester system combining PCT with isophthalic acid and/or ethylene glycol copolymer components, achieving a balance between crystallization rate and processability that enables both rapid crystallization and ease of manufacturing amorphous articles
2Stability of the object's composition
If sufficient ethylene glycol is included in copolyester formulation to provide long crystallization half-times, then amorphous products with higher ductile-to-brittle transition temperatures are achieved, but glass transition temperature and impact strength are reduced
Solution Approach 1:
The patent optimizes the compositional parameters by limiting ethylene glycol content to specific ranges (0.01-15 mole %) while adjusting isophthalic acid content and using 2,2,4,4-tetramethyl-1,3-cyclobutanediol to achieve the desired ductile-to-brittle transition temperature without sacrificing impact strength
Solution Approach 2:
The invention introduces 2,2,4,4-tetrawethyl-1,3-cyclobutanediol as an intermediary component that mediates between the conflicting requirements of long crystallization half-times and high impact strength, enabling both properties to coexist in the copolyester composition
3Strength
If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used in polyester composition, then improved toughness and chemical resistance are achieved, but inherent viscosity and melt viscosity increase, making standard industry equipment insufficient
Solution Approach 1:
The patent controls the content of 2,2,4,4-tetramethyl-1,3-cyclobutanediol within specific ranges (1-99 mole %) and adjusts the overall composition parameters including inherent viscosity (0.10-1.0 dL/g) to maintain melt processability on standard equipment while achieving improved toughness
Solution Approach 2:
The invention applies 2,2,4,4-tetrawethyl-1,3-cyclobutanediol at specific local concentrations within the copolyester structure, providing toughness enhancement at targeted locations while maintaining overall processability through controlled distribution and concentration
4Temperature
If bisphenol A polycarbonate is used as alternative, then high heat resistance and good impact strength are achieved, but relatively high melt viscosity leads to poor melt processability and difficult thermoforming
Solution Approach 1:
The patent modifies the thermal and rheological parameters by using polyester copolymers with adjustable glass transition temperatures (85-135°C) and melt viscosities, achieving heat resistance comparable to polycarbonate while maintaining excellent melt processability and thermoformability
Solution Approach 2:
The invention replaces expensive and difficult-to-process polycarbonate with a more economical polyester copolymer that achieves similar heat resistance properties but with superior processability, effectively substituting a difficult material with an easier alternative
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 proposed polyester composition enables thermoforming of sheets and films with improved toughness, chemical resistance, and heat resistance, while maintaining processability on standard industrial equipment, overcoming the limitations of existing materials.
Implementation Method 1
thermoformed sheets and/or films comprising polyester compositions... which allow them to be easily thermoformed
Implementation Method 2
moderate glass transition temperature (Tg)... lower ductile to brittle temperatures
Data Source
AI summary
Described are thermoformed films or sheets comprising polyester compositions comprising polyesters which comprise (a) a dicarboxylicacidcomponent having terephthalic acid or an ester thereof; optionally, an aromatic dicarboxylic acid or aliphatic dicarboxylic acid or esters thereof; 2,2,4,4-tetramethyl-1,3-cyclobutanediol; and 1,4-cyclohexanedimethanol.