On July 24, 2026, the China National Intellectual Property Administration published that Wanhua Chemical Group Co., Ltd. (600309) has been granted a new invention patent titled “Toluene Diisocyanate Production System and Toluene Diisocyanate Production Method”. The patent, with authorisation number CN121338372B and application number CN202511495652.1, was filed on October 20, 2025.
Core Innovation: An Integrated Dividing Wall Column System Achieving “Three Birds with One Stone”
The patent’s core innovation lies in a pipework system that integrates a rectification column with a dividing wall column (DWC). The top and bottom of the rectification column are respectively connected to the middle section of the DWC, forming an efficient thermal and mass coupling loop.
The internal structure of the DWC is divided into three functional sections:
- Rectifying section (near the top): removes light-component impurities;
- Isomer control section (middle): precisely adjusts the TDI isomer ratio;
- Stripping section (near the bottom): concentrates heavy-component impurities.
This design achieves three major objectives simultaneously: high-efficiency impurity removal, precise isomer ratio control, and energy consumption optimisation. The ratio of the two TDI isomers – 2,4- and 2,6-TDI – directly affects the processing performance and mechanical properties of downstream polyurethane products. This patent enables the production of TDI products with controllable isomer ratios.
Why It Matters: The “Purification Battle” for High-End TDI
TDI is a core raw material for flexible polyurethane foams, coatings, and adhesives. High-end applications – such as low-odor foams for automotive interiors, premium furniture, and electronic-grade adhesives – demand extremely strict purity (especially hydrolysable chlorine content) and isomer ratio stability. In traditional production systems, impurity removal and isomer ratio control often conflict with each other, making it difficult to achieve both. This patent, through dividing wall column technology, couples rectification and isomer separation in a single column, reducing capital investment and energy consumption while significantly improving precision.
R&D Strength: High-Intensity Investment Driving Innovation
The inventors of this patent are Wei Libin, Hu Miao, Deng Rulei, Liu Qian, and Zhao Dongke. The patent agency is Huajin United Patent & Trademark Agency Co., Ltd.
Wanhua Chemical continues to increase its R&D investment: its full-year 2025 R&D expenditure reached RMB 4.865 billion, up 6.92% year-on-year. So far this year, the company has been granted 445 new patents, a significant increase of 55.59% compared to the same period last year. According to big-data analysis from Tianyancha, Wanhua Chemical holds a total of 7,186 patent records.
Industry Context: The Global TDI Leader’s “Technology Moat”
Wanhua Chemical has become the world's largest TDI supplier, with a total capacity of 1.47 million tonnes per year, accounting for more than 40% of the global total. The company's current MDI capacity stands at 3.80 million t/a and TDI capacity at 1.47 million t/a, both ranking among the global top tier.
This patent comes at a time when Wanhua Chemical's Hungarian subsidiary, BorsodChem, began a 35-day scheduled maintenance shutdown of its 250,000 t/a TDI plant on July 17. Securing this core process patent during a period of supply-side contraction further consolidates Wanhua’s technological moat in the global TDI field.
From MDI to TDI, Wanhua Chemical is replicating its technology self-sufficiency strategy across the isocyanate sector – leveraging sustained, high-intensity R&D investment to drive process innovation and build an increasingly deep technology moat in the global polyurethane raw material competition.
