Our company is Yixing Wencheng Chemical Co., Ltd., a manufacturer of polyol series fine chemicals. We have been engaged in the production and sales of polyol series and their derivatives for 30 years. 1,4-Butanediol, as an important part of the polyol series, is one of our company's core products. Globally, 40% to 45% of BDO is used to produce tetrahydrofuran (THF). THF repolymerization yields polytetrahydrofuran ether PTMEG, which is the sole raw material for spandex (spandex elastic fiber). Spandex is a material used to produce polyurethane elastomers, artificial leather, waterproof coatings, medical catheters, and seals. Below, I will share some key points about this supply chain based on our domestic and international production and sales experience, hoping to help those who need it.
In actual large-scale production, 1,4-butanediol is first used as the core raw material. Under the action of a specific catalyst, an intramolecular dehydration cyclization reaction is carried out to generate tetrahydrofuran (THF). After the crude THF is refined and purified, high-purity THF monomer is obtained. Then, polytetrahydrofuran ether (PTMEG) is synthesized through cationic ring-opening polymerization. Finally, PTMEG is subjected to chain extension and polymerization reactions with auxiliary materials such as diisocyanate to finally prepare spandex products with excellent elastic properties. The entire production process has high requirements for process parameters, production environment and raw material quality, and several key points need to be controlled during the production process. Firstly, the dehydration and cyclization reaction of 1,4-butanediol requires precise control of reaction temperature, pressure, and catalyst dosage to effectively suppress side reactions, reduce impurity formation, and ensure the purity of THF products. Secondly, THF is volatile, flammable, and explosive, necessitating a closed-loop operation throughout the production process. Strict control of open flames and static electricity generation is required, along with adequate explosion-proof ventilation in the workshop to prevent accidents. Thirdly, the PTMEG polymerization reaction is highly sensitive to raw material purity. THF raw materials must undergo thorough dehydration and impurity removal to prevent impurities and moisture from affecting the polymer molecular weight, which could lead to substandard elasticity, mechanical strength, and other core properties of spandex. Fourthly, temperature, feed rate, and reaction rate must be steadily controlled at each stage of the reaction to prevent excessively vigorous reactions, eliminate safety risks, and ensure stable and uniform product quality.
In the BDO→THF→PTMEG→spandex production chain, 1,4-butanediol is the source raw material, and its quality indicators will affect the performance of intermediate products and finished products step by step. Therefore, production has strict restrictions on the purity, moisture, acidity, metal ions and various impurities of BDO. The process requires the use of high-quality BDO with a purity of ≥99.5%. Impurities such as alcohols, esters, and olefins introduced due to insufficient purity will induce side reactions, increase the THF purification load, and reduce product yield and purity. The moisture content of BDO needs to be controlled within 0.03%. Excessive moisture will damage the THF polymerization catalytic system, resulting in a lower molecular weight and wider distribution of PTMEG, which will reduce the elasticity and strength of spandex, while also aggravating equipment corrosion and increasing energy consumption. BDO color must be ≤10# and acidity ≤0.002%. Trace amounts of acidic substances will accelerate catalyst deactivation, while colored unsaturated impurities will cause a difference in yellowing between PTMEG and spandex, affecting the appearance quality. Metal ions such as iron, sodium, and potassium must be kept at ppm levels; they not only catalyze BDO oxidation—generating harmful impurities—but also poison polymerization catalysts, causing system instability and product performance fluctuations. At the same time, it is necessary to strictly control high-boiling-point heavy components and unsaturated impurities to prevent heavy components from clogging distillation equipment and unsaturated components from causing polymer branching and cross-linking, which would degrade the PTMEG structure and the fatigue resistance of spandex. Furthermore, BDO ash content must be below 0.001% with no mechanical impurities to avoid safety hazards such as equipment wear, catalyst bed clogging, and system pressure fluctuations. Therefore, exceeding the standards for various BDO indicators will have a chain of negative effects along the process. Thus, high-purity, low-impurity high-quality BDO is the core prerequisite for ensuring stable spandex production and finished product quality. Yixing Wencheng Chemical Co., Ltd. is a high-quality BDO manufacturer, and our BDO has been widely and long-term used in this production chain.
Given the numerous stages in this production chain, we recommend utilizing by-products and recyclable materials throughout the entire process. Therefore, each section can be equipped with a complete material and energy recycling system. At the raw material end, unreacted BDO can be recovered, and BDO can be regenerated through the cracking of dibutyl butylene glycol for reuse. The THF production section can recycle crude THF fraction and process water, and regenerate the dehydration catalyst for reuse. The PTMEG production section can recover free THF monomers, alkane extractants, and unconsumed acetic acid/acetic anhydride. It can also depolymerize unqualified PTMEG to regenerate THF, and the polymerization catalyst can be recycled after regeneration. The spandex spinning section mainly realizes the closed-loop circulation of DMF/DMAc spinning solvent, and recovers PTMEG and THF materials through the depolymerization of waste fibers. In addition, the entire production line can use light fusel oil as fuel gas and tar for heating, while recovering waste heat from the entire production process, realizing the dual recycling of production materials and energy, effectively reducing production losses and energy costs.
Global annual BDO production capacity exceeds 3.5 million tons, with China accounting for more than 70% of the global capacity, making it a core region for global production and export. Our company's high-quality BDO and other polyol series products are stable in performance and excellent in quality. They are exported to many countries around the world and are widely used in the polyester industry, tetrahydrofuran (THF), biodegradable plastics, engineering plastics and other industries. With 30 years of experience in the industry, we have always adhered to quality and stable production capacity. We sincerely welcome customers from all walks of life to consult, discuss, and cooperate with us!
