Polyester Copolymer Production via Isosorbide Transesterification
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Solution Overview
Problem
Current PET recycling processes face challenges in producing high isosorbide content polyester copolymers with high molecular weight and improved properties, such as thermal stability and mechanical strength, due to the low reactivity of secondary hydroxyl groups in isosorbide, limiting their commercial viability and application potential.
Innovation Solution
A chemical recycling process that reacts polyethylene terephthalate with (bi)cyclic secondary diols like isosorbide and (hetero)aromatic dicarboxylic acids without ethylene glycol, involving a one-pot esterification/transesterification and polycondensation at controlled temperatures and pressures to produce polyester copolymers with high isosorbide content and molecular weights exceeding 16,500 daltons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If (bi)cyclic secondary diols like isosorbide are used to produce polyester copolymers, then glass transition temperature and thermal stability are improved, but reactivity is reduced due to secondary hydroxyl groups
Solution Approach 1:
The patent changes the reaction parameters by using elevated temperatures (200-300°C) and extended reaction times to compensate for the lower reactivity of secondary hydroxyl groups. The process also uses a catalyst system and controls the molar ratios of reactants to facilitate polymerization despite the reduced reactivity, thereby achieving high glass transition temperatures while maintaining acceptable reaction rates
Solution Approach 2:
The patent employs preliminary action by first conducting transesterification reactions to break down PET into oligomers and monomers before introducing the (bi)cyclic secondary diols. This preliminary depolymerization creates more reactive end groups that can more easily react with the secondary hydroxyl groups, thereby overcoming the reactivity limitation while still achieving the desired thermal properties
2Strength
If chemical recycling processes are used to produce high value derivatives, then material properties are improved, but production costs increase compared to virgin PET
Solution Approach 1:
The patent achieves multi-functionality by using a single chemical recycling process that simultaneously accomplishes depolymerization, purification, and copolymerization in one integrated system. This eliminates the need for separate processing steps, reduces equipment requirements, and lowers operational costs while producing high-value polyester copolymers with improved mechanical and thermal properties
Solution Approach 2:
The patent applies discarding and recovering by taking waste PET material that would otherwise be discarded or downcycled and transforming it into high-value polyester copolymers. The process recovers valuable monomers and oligomers from waste PET and reuses them in the copolymerization reaction, thereby converting waste into a premium product with superior properties at reduced production cost
3Quantity of substance
If high molecular weight polyester copolymers are produced through chemical recycling, then material performance is improved, but reaction time and process complexity increase
Solution Approach 1:
The patent implements continuity of useful action by maintaining continuous heating, stirring, and vacuum application throughout the polymerization process. The reaction proceeds in a continuous manner without interruption, with temperature and pressure continuously adjusted to optimize polymerization rate and molecular weight buildup, thereby achieving high molecular weights in reduced time
Solution Approach 2:
The patent uses periodic action by applying vacuum in intermittent cycles during the polymerization process. The vacuum is applied periodically to remove condensation products (water, alcohol) that inhibit further polymerization, allowing the reaction to proceed in bursts of high activity. This periodic vacuum application accelerates molecular weight buildup compared to continuous vacuum methods
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 process enables the production of polyester copolymers with tunable properties, including high glass transition temperatures and improved mechanical and thermal stability, suitable for various industrial applications, while utilizing renewable materials and reducing production costs.
Implementation Method 1
reacting a polyester with one or more diols and one or more dicarboxylic acids or esters thereof
Implementation Method 2
the components (i) and (ii) are used in sufficient quantities to produce a polyester copolymer
Implementation Method 3
heating the mixture of polyester (i), the one or more diols (ii) and the one or more (hetero)aromatic dicarboxylic acids or any esters thereof (iii) to form a melt
Data Source
AI summary
A polymerization process for the production of a polyester copolymer A comprising simultaneously reacting a polyester (i) with one or more diols (ii) and one or more (hetero)aromatic dicarboxylic acids or any esters thereof (iii), wherein the polyester (i) is polyethylene terephthalate, polyethylene furanoate or polyethylene terephthalate-co-furanoate; and wherein no ethylene glycol is added as a diol (ii); and wherein at least one of the one or more diols (ii) is selected from (bi)cyclic secondary diols; and wherein the components (i) and (ii) are used in sufficient quantities to produce a polyester copolymer A comprising at least 40 mole % of ethylene glycol derived from the starting polyethylene terephthalate, polyethylene furanoate or polyethylene terephthalate-co-furanoate, and at least 5 mole %, preferably equal to or more than 10 mole %, of monomers derived from said (bi)cyclic secondary diol(s), the percentages based on the total amount of diol-derived monomer units in polyester copolymer A; and wherein the process comprises heating the mixture of polyester (i), the one or more diols (ii) and the one or more (hetero)aromatic dicarboxylic acids or any esters thereof (iii) to form a melt, comprising the steps (a) to (d): (a) in a reaction vessel heating the polyester (i), the one or more diols (ii) and the one or more (hetero)aromatic dicarboxylic acids or any esters thereof (iii) to a certain temperature high enough to form a slurry/melt, so that the reaction mixture has a temperature from at least 220 oC to 260 oC, for a certain period of time until a clear melt forms, specifically being 120 to 250 minutes, at a pressure of 1 to 5 bar; (b) continuing the esterification/transesterification reaction for a period of 60 to 100 minutes while gradually increasing the temperature of the reaction mixture to a temperature not higher than 270 oC and gradually reducing the pressure to atmospheric pressure; (c) while starting at the same temperature as the temperature of step (b), treating the product resulting from step (b) with a pressure lower than 20 mbar, preferably lower than 10 mbar, and more preferably lower than 5 mbar with continued stirring for 60 to 240 minutes; and optionally at the end of step (c), in order to easily discharge the polyester, further increasing the temperature by 0.1 oC to 50 oC to a temperature not higher than 285 oC; and (d) discharge the polyester at a pressure of 1 to 5 bar; and to generate a polyester A comprising monomer units derived from the polyester (i), the one or more diols (ii) and the one or more (hetero)aromatic dicarboxylic acids or any esters thereof (iii), having a number average molecular weight, as measured by gel permeation chromatography with PMMA standards as reference material, of 16500 daltons or more, and having a polydispersity index in the range from equal to or higher than 1.6 to equal to or lower than 2.6.