Recycled Polyester Copolyester-ether Film Preparation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for preparing copolyester-ether films face challenges such as uneven molecular weight distribution, poor mechanical properties, and unsuitability for applications requiring flexibility and breathability, particularly due to rapid crystallization and the use of harmful byproducts like tetrahydrofuran.
Innovation Solution
A method involving the alcoholysis of recycled polyester with a diol to form an intermediate, followed by transesterification and polymerization with a polyol, which results in a copolyester-ether film with controlled crystallization speed and improved flexibility, using a catalyst and additives to enhance properties like thermostability and UV resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional transesterification method using DMT and diol is used, then copolyester-ether can be produced, but byproducts like methanol and THF are generated causing side reactions and uneven molecular weight distribution
Solution Approach 1:
The patent changes the chemical parameters of the transesterification reaction by using recycled polyester instead of DMT as the reactant. This parameter change eliminates the formation of methanol byproduct while maintaining the transesterification reaction efficiency, thereby preventing side reactions and improving molecular weight distribution uniformity
Solution Approach 2:
The patent converts the harmful effect of using recycled polyester (which may have impurities and variable molecular weight) into a benefit by demonstrating that it actually reduces byproduct formation and side reactions. The recycled polyester serves as a sustainable raw material that eliminates THF and methanol generation while producing uniform molecular weight distribution when processed through the optimized transesterification method
2Strength
If PTMEG is used as soft segment, then copolyester-ether has good elasticity, but it dissociates to THF at high temperature which is harmful to humans and environment
Solution Approach 1:
The patent extracts and removes the problematic PTMEG soft segment from the copolyester-ether structure. By replacing PTMEG with alternative soft segments that do not dissociate to THF at high temperature, the invention eliminates the harmful byproduct generation while maintaining or improving the elastic properties of the material
Solution Approach 2:
The patent adopts a more sustainable and environmentally friendly approach by selecting soft segment materials that are stable at high temperatures and do not generate harmful byproducts. This replacement ensures the material is safe for applications requiring high temperature processing and is environmentally benign
3Speed
If PBT is used as hard segment, then crystallization rate is fast providing good dimensional stability, but it is not suitable for extension molding due to too-fast crystallization causing broken film or uneven thickness
Solution Approach 1:
The patent applies local quality by creating a copolyester-ether structure with heterogeneous composition - combining PBT hard segments (for crystallization) with PET segments and alternative soft segments. This local variation in molecular structure allows different regions of the polymer to exhibit different properties: some regions provide fast crystallization while others control the overall crystallization kinetics to be suitable for extension molding
Solution Approach 2:
The patent creates a composite copolyester-ether material by combining different polyester components (PBT and PET) with alternative soft segments. This composite structure synergistically combines the fast crystallization capability of PBT with the processability advantages of PET, achieving both rapid crystallization and suitability for extension molding without film defects
4Temperature
If PET is used as hard segment, then heat resistance is improved due to higher melting point, but crystallization rate is slower than PBT
Solution Approach 1:
The patent creates a composite copolyester-ether structure combining PET hard segments (providing heat resistance) with PBT segments (providing fast crystallization). This composite approach allows the material to simultaneously achieve high heat resistance from PET and rapid crystallization from PBT, overcoming the limitations of using either component alone
Solution Approach 2:
The patent introduces local quality variations by incorporating both PET and PBT segments within the copolymer structure. The PET segments provide heat resistance in regions requiring thermal stability, while PBT segments provide fast crystallization in regions where rapid solidification is needed, achieving both properties at the molecular level
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 method produces a waterproof, breathable, flexible copolyester-ether film with a Young's modulus of 60-210 MPa and water vapor transmission rate of 600-6000 g/m2/day, suitable for fabric applications, while avoiding harmful byproducts and ensuring environmental safety.
Implementation Method 1
Alcoholysis is performed by reacting the recycled polyester with a diol to form a first intermediate
Implementation Method 2
Transesterification is performed to the first intermediate to form a second intermediate
Implementation Method 3
The copolyester-ether film is waterproof and breathable, with a water vapor transmission rate of 600-6000 g/m2/day
Data Source
AI summary
A method for preparing a copolyester-ether film is provided, wherein the method includes a recycled polyester is provided. Alcoholysis is performed by reacting the recycled polyester with a diol to form a first intermediate, wherein the molar ratio of the recycled polyester to the diol is 1:1.8-2.5. Transesterification is performed to the first intermediate to form a second intermediate, wherein the temperature of transesterification is between 190° C. and 230° C. A polyol is added to the second intermediate and polymerization is performed to form a copolyester-ether, wherein the weight percent of the polyol in the copolyester-ether is 24-55%. The copolyester-ether is manufactured into a flexible film.