Recycled PET Polyester Conversion for Bright White Electronics Housings
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Solution Overview
Problem
Existing thermoplastic compositions derived from post-consumer or post-industrial recycled polyethylene terephthalate (PCR) face challenges in achieving certain colors, particularly bright white, due to residual colorants or contaminants, limiting their suitability for consumer electronics applications.
Innovation Solution
A method involving depolymerizing PCR PET to form bis(2-hydroxyethyl) terephthalate (BHET), reacting it with catalysts to form alcohols like cyclohexanedimethanol (CHDM) or 1,4-phenylenedimethanol (PDM), and polymerizing these alcohols to create polyesters such as poly(cyclohexylenedimethylene terephthalate (PCT), polyethylene terephthalate glycol (PETG) copolyester, or polycyclohexylene dimethylene terephthalate glycol (PCTG) copolyester, enhancing the sustainable content without using externally sourced bio-based butanediol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If post-consumer or post-industrial recycled polyethylene terephthalate (PCR) is used in thermoplastic compositions, then sustainable content is improved, but color quality deteriorates due to residual colorants or contaminants preventing bright white color achievement
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the polyester through copolymerization with different diols (ethylene glycol, butanediol, hexanediol, cyclohexanedimethanol) to alter the polymer's optical properties. By changing the molecular composition and introducing different repeating units, the material achieves bright white color while maintaining high sustainable content from PCR feedstock
Solution Approach 2:
The patent creates composite polyester materials by combining multiple diol units in copolymer structures. The thermoplastic compositions contain copolymers with repeating units from different diols (e.g., ethylene glycol and butanediol, or cyclohexanedimethanol units), creating a composite material that achieves both sustainability and optical quality
2Adaptability or versatility
If PCR components are included in injection molded materials, then environmental sustainability is improved, but manufacturing precision deteriorates due to difficulty in achieving certain colors
Solution Approach 1:
The patent changes the chemical parameters of the polyester by incorporating different diol units (ethylene glycol, butanediol, hexanediol, cyclohexanedimethanol) to precisely control the material's optical properties. This allows achievement of bright white color with high color accuracy while maintaining sustainability from PCR feedstock
Solution Approach 2:
The patent applies local quality by creating specific repeating units with particular diol structures at controlled positions in the polymer chain. By localizing specific diol units (such as cyclohexanedimethanol or butanediol) within the copolymer structure, the material achieves precise color properties while maintaining overall sustainability
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 enables the production of polyesters with higher sustainable content, achieving desired colors like bright white, thereby meeting the requirements for consumer electronics applications.
Implementation Method 1
reacting it with a catalyst to form an alcohol
Implementation Method 2
polymerizing the alcohol in the presence of additional BHET to form a polyester
Data Source
AI summary
A method includes depolymerizing post-consumer or post-industrial recycled polyethylene terephthalate (rPET) to form bis(2-hydroxyethyl) terephthalate (BHET), and reacting at least a portion of the BHET with a catalyst to form an alcohol. The alcohol includes cyclohexanedimethanol (CHDM) or 1,4-phenylenedimethanol (PDM). Further steps of the method include polymerizing the alcohol in the presence of additional BHET to form a polyester. The polyester may include poly(cyclohexylenedimethylene terephthalate (PCT), polyethylene terephthalate glycol (PETG) copolyester, polycyclohexylene dimethylene terephthalate glycol (PCTG) copolyester, polycyclohexylene dimethylene terephthalate acid (PCTA), or a monomer having repeating units with the structure (I), wherein n is an integer having a value of at least 20.