🆕 on ppPLUS: Polyester Formation via Polycondensation — Technology Review
Polyesters are step-growth polymers built by combining a dicarboxylic acid (or its ester) with a diol, releasing water or alcohol as the reaction proceeds. PET is the largest-volume example, but the same chemistry underlies PBT, PTT, PEN, & biodegradable copolyesters like PBAT.
🧪 Chemistry Fundamentals
Two monomer routes converge on the same oligomeric intermediate: direct esterification (acid + diol, releasing water) or transesterification (diester + diol, releasing alcohol). Both proceed to BHET or its analogues, which then polycondense into the final polymer with loss of additional diol.
1️⃣ 0️⃣ 0️⃣ A Century of Process Development
The chemistry traces back to Carothers' foundational polycondensation work in 1928–1932, followed by Whinfield and Dickson's terephthalic acid–ethylene glycol breakthrough in the early 1940s, and commercial scale-up by ICI and DuPont from 1947. PTA technology from Standard Oil/Amoco by 1963 later shifted the industry away from DMT-transesterification toward direct PTA esterification, the dominant route today.
⚗️▶️⚗️ Two-Stage Industrial Process
Every commercial route follows the same macro-structure: esterification/transesterification to build a low-DP oligomer, followed by melt-phase polycondensation under vacuum to reach usable molecular weight, with solid-state polymerization added when melt-phase degradation caps the achievable IV. For PET, melt phase reaches IV 0.60–0.68 in roughly 2–2.5 hours, and SSP then raises IV to 0.72–0.85 over 10–15 hours while cutting acetaldehyde below 2 ppm.
✴️ Catalysis in Transition
Antimony trioxide remains the dominant catalyst industry-wide, but titanium alkoxide systems are gaining ground for their lower dosage and improved environmental profile — a shift confirmed at commercial scale by Clariant's 2023 EcoAn titanium catalyst launch, engineered across the entire polyester family.
®️ Licensor Landscape Has Consolidated
Ownership of key technologies has shifted substantially: Uhde Inventa-Fischer's MTR technology remains actively licensed (KOKSAN 2021, SASA Polyester 2022), while Zimmer, Eastman's Integrex, & Mossi & Ghisolfi's SSP technology have all passed to new owners — Technip Energies, DAK Americas/Alpek, & a mix of Alpek/FENC/Corpus Christi Polymers, respectively. Chinese producers like Hengli Group have meanwhile developed fully vertically integrated, non-licensed polymerization technology at multi-million-tonne scale.
📰 Read this comprehensive review on ppPLUS: https://lnkd.in/eV8cQs_7
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INVISTA Koch Koch Business Solutions India Koch Engineered Solutions thyssenkrupp Uhde Eastman Alpek Hengli Group Sinopec International Petroleum Service Corporation
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