PBT Industry Outlook: New Paradigms for Growth Driven by Bio-based Materials, Circular Economy And New Energy

PBT Industry Outlook: New Paradigms for Growth Driven by Bio-based Materials, Circular Economy And New Energy

PBT (polybutylene terephthalate), one of the five major engineering plastics and a member of the polyester family, is primarily produced through the condensation of terephthalic acid (PTA) and 1,4-butanediol (BDO). Known for its high heat resistance, though not resistant to strong acids and bases, PBT is widely used in the production of spandex, masterbatches, food packaging films, iris membranes, and more. With the expanding demands of downstream industries and successive new capacity additions by enterprises, China's PBT industry has achieved remarkable growth. In 2023, China's PBT output reached 920,000 tons, with a demand of 750,000 tons, primarily driven by the electronics, electrical, and automotive sectors.

I. PBT Overview

PET, commonly known as polyethylene terephthalate or polyester, is a thermoplastic resin that, along with PBT (polybutylene terephthalate), falls under the category of thermoplastic or saturated polyesters. PET is synthesized by ester exchange of dimethyl terephthalate with ethylene glycol or by esterification of terephthalic acid with ethylene glycol, followed by polycondensation to form polyethylene terephthalate. It is a crystalline, saturated polyester, appearing as milky white or pale yellow with a highly crystalline structure and a smooth, glossy surface. PBT is a common resin in daily life, exhibiting excellent physical and mechanical properties across a wide temperature range. It can be used at temperatures up to 120°C, has good electrical insulation properties, and maintains relatively stable electrical performance even at high temperatures and frequencies. However, it has poor resistance to corona discharge, and its anti-creep, fatigue, wear resistance, and dimensional stability are all relatively good.

1. Production Processes

There are two main methods for producing PBT: the transesterification process and the direct polycondensation process. The catalysts used include tetraisopropyl titanate, tetrabutyl titanate, zirconium alkoxide, stannous alkoxide, and others.

• Transesterification Process

The transesterification process uses dimethyl terephthalate (DMT) as the raw material, which first undergoes transesterification with 1,4-butanediol to form bis(2-hydroxyethyl) terephthalate, which is then polycondensed to form polybutylene terephthalate. The transesterification process uses an excess molar ratio of 1,4-butanediol to DMT, ranging from 1:1.3 to 1:1.7. The reaction temperature is approximately 200°C, which favors the equilibrium towards the formation of bis(2-hydroxyethyl) terephthalate and reduces side reactions. The subsequent polycondensation reaction is carried out at a temperature of about 250–260°C under a reduced pressure of 0.1–1 mm Hg. The transesterification process can be conducted either batch-wise or continuously. Its advantages include relatively simple equipment, mild reaction conditions, and easy control of the transesterification and polycondensation steps separately. However, batch production is less efficient.

• Continuous Direct Esterification Process

The continuous direct esterification and polycondensation technology is relatively complex, as the process involves materials in a high-temperature, high-vacuum molten state, posing challenges in terms of equipment materials, structure, material conveyance, and reaction condition control. Consequently, several patented technologies have been developed. Notable examples include the Lurgi Zemmer technology, which features three reactors for esterification, pre-polycondensation, and polycondensation. The polycondensation reactor is a horizontal disc-type reactor, with a single production line capable of reaching an annual capacity of 120,000 tons. This technology yields high-quality products, and the byproduct tetrahydrofuran can be directly used in the production of polytetrahydrofuran. The Hitachi technology in Japan comprises four different types of reactors and can simultaneously produce high-viscosity and medium-viscosity products, with a single production line capacity of up to 60,000 tons per year. The Uhde Inyenta Fischer technology employs a tower-type reactor where esterification and polycondensation can be completed in a single reactor. It can produce PBT products with a polymerization degree of 20–35. For products with a polymerization degree of 80–150, the process can be shifted to another reactor called DISCAGE for horizontal polycondensation.

2. Industrial Chain

3. Performance Advantages

In terms of mechanical properties: PBT demonstrates high strength, high rigidity, and good toughness. Modified PBT can withstand significant external forces without deformation or breakage and exhibits excellent fatigue resistance. After multiple cyclic loadings, it can maintain structural integrity, making it suitable for manufacturing various parts with high mechanical property requirements.

In terms of heat resistance: PBT has a high heat distortion temperature and can be used across a wide temperature range. It can typically be used long-term at temperatures of 120°C–140°C, and short-term use can even reach above 180°C. This enables it to maintain good performance stability in high-temperature environments, meeting the material requirements for heat-generating components in electronics, electrical, and automotive applications.

In terms of chemical properties: PBT also has excellent chemical stability and shows good resistance to most chemical reagents. It is not prone to chemical reactions in general acidic, alkaline, or organic solvent environments. It only undergoes partial hydrolysis under extreme conditions such as strong acids, strong bases, and high-temperature steam. This provides reliable assurance for its applications in chemical and automotive fields, effectively resisting the erosion of various chemicals and extending the service life of components.

In terms of electrical properties: PBT has excellent electrical properties, with high insulation and stable dielectric constant. It can maintain good electrical performance even in humid or high-temperature environments, making it an ideal material for manufacturing electronic and electrical parts. It is widely used in electronic connectors, relays, switches, and other components, ensuring the safe and stable operation of electronic devices.

Other characteristics: PBT has low water absorption, and moisture absorption has minimal impact on its physical properties and dimensional stability. It can maintain relatively stable performance in different humidity environments, reducing dimensional changes and performance degradation caused by water absorption. This ensures product precision and reliability.

In terms of processing: PBT also has good processability, with fast crystallization and good fluidity. It can be easily processed into various complex shapes through injection molding, extrusion, and other forming methods. It has a short forming cycle and high production efficiency, meeting the demands of large-scale industrial production and reducing production costs.

II. Current Status of the PBT Industry

Global PBT production capacity is mainly concentrated in Asia, Europe, the Americas, and the Middle East, including countries such as China, the United States, Germany, Japan, and Saudi Arabia.

China began developing PBT technology in the 1970s and successively established small-scale production facilities ranging from hundreds to thousands of tons. However, due to immature process technologies and raw material supply issues, the operating rates of these facilities remained relatively low. In 1997, Yizheng Chemical Fiber built a 20,000-ton-per-year PBT engineering plastic production facility, introducing technology and equipment from Germany's Gima Company. It also adopted the compounding equipment and formulations from Switzerland's Buss Company. Combining foreign advanced technologies with the company's self-produced PTA advantages, this marked a significant step forward for China's PBT industry.

With the expanding demands of downstream industries and new capacity additions by enterprises, China's PBT industry has achieved significant growth. In 2023, China's PBT output reached 920,000 tons, with a demand of 750,000 tons. The electronics, electrical, and automotive sectors are the primary consumption areas. By 2025, China's PBT production capacity plus planned capacity will exceed 1.5 million tons. The main production capacity is concentrated in coastal eastern regions such as Jiangsu, Zhejiang, and Guangdong, which leverage their well-developed PBTrochemical industries and geographical advantages to become the largest PBT production bases in the country.

During this period, the electronics and electrical sector, as one of the main application fields for PBT, has seen continuous growth in PBT demand driven by the popularity and upgrading of smartphones, tablet computers, wearable devices, and other electronic products, thereby expanding the market size. The development of the automotive industry, particularly the rise of new energy vehicles, has also increased the demand for lightweight and high-performance materials, expanding the application of PBT in automotive components and further driving market growth.

In 2023, China accounted for approximately 45% of the global PBT market share, a figure that continues to rise and is currently nearing 50%. This growth is mainly attributed to policy support, technological advancements, and market demand drivers, with explosive growth in new energy vehicles, 5G base stations, and consumer electronics supply chains.

III. Development of PBT Downstream Applications

1. Electronics and Electrical Sector

In the electronics and electrical field, PBT (polybutylene terephthalate) is undergoing dual transformations of technological iteration and application expansion, driven by emerging demands such as 5G communication, smart homes, and consumer electronics upgrades.

In electronic devices, PBT is commonly used to manufacture components such as connectors, switches, relays, and transformers. For instance, connectors, as key components for transmitting electronic signals, require materials with good mechanical properties, electrical insulation, and dimensional stability. By adding glass fibers and other reinforcing materials, PBT can meet these requirements, ensuring stable and reliable signal transmission in electronic devices. In switches and relays, PBT's heat resistance and chemical corrosion resistance enable it to maintain good performance during long-term use, preventing material aging and performance degradation caused by high temperatures and chemical substances.

As the world's largest producer and consumer of consumer electronics, China's demand for high-performance plastics continues to grow with the widespread adoption of 5G technology, the accelerated replacement of smartphones, and stable market demand for products such as tablet computers and notebook computers. PBT, with its excellent heat resistance, dimensional stability, and electrical insulation properties, is widely used in internal components, structural parts, circuit boards, and connectors of these devices, with future demand expected to increase. For example, the emergence of foldable smartphones imposes higher requirements on the flexibility and strength of PBT materials, driving technological innovation and demand growth in PBT materials.

2. Automotive Sector

PBT is widely used in automotive manufacturing for interior and exterior trim, engine components, and electronic and electrical systems. In new energy vehicles (especially pure electric vehicles), PBT is in high demand for battery systems, motor controllers, and electric drive modules. For example, battery connectors and battery housings (which need to withstand electrolyte corrosion) show a significant increase in demand for PBT. Meanwhile, PBT composites can replace metal components (such as aluminum alloys), reducing vehicle weight and improving driving range. Under the premise of ensuring performance, PBT composites are gradually replacing metals (such as zinc alloys and cast iron), reducing costs and simplifying processing procedures. For instance, engine intake manifolds are transitioning from aluminum alloys to glass fiber-reinforced PBT. Additionally, the trend towards modular integration of automotive components is met by PBT's high molding precision and capability for complex structural molding (such as thin-walled and precision injection molding), satisfying design requirements.

As the world's largest automotive producer and a key market for new energy vehicles, China's automotive manufacturers are leading global PBT demand growth. Particularly in the context of localized supply chains for new energy vehicles, domestic PBT producers (such as Jiangsu Sfangxiang and Xiamen International Trade) are gradually increasing their market share.

3. Industrial Machinery Sector

PBT is used to manufacture various mechanical parts, such as gears, cams, bearings, and chains. Its high strength, rigidity, and wear resistance enable it to withstand friction and impact forces during mechanical operation, extending the service life of components and enhancing the efficiency and reliability of machinery. In industries such as textile machinery, packaging machinery, and printing machinery, PBT components are widely applied. With the continuous improvement of industrial automation, the demand for high-performance engineering plastics is expected to grow steadily, providing broad application prospects for PBT in this field.

However, the demand for PBT in China's industrial machinery sector may be influenced by factors such as raw material price fluctuations, which can impact PBT production costs and market prices. Additionally, intense market comPBTition, overcapacity of mid-to-low-end PBT products, and insufficient self-sufficiency in high-end products may lead to increased focus on cost-effectiveness and performance improvements in PBT products when selected for industrial machinery applications.

4. Optical Cable Sector

PBT (polybutylene terephthalate) is utilized in the optical cable industry to manufacture critical components such as sheaths, loose tube sleeves, and cable reinforcement members. Its excellent mechanical properties, chemical corrosion resistance, and environmental adaptability make it a key material in the optical cable sector.

During the "Twelfth Five-Year Plan" period, rapid economic development spurred demand for information transmission bandwidth, and the advantages of optical communication technology became increasingly evident. Driven by policies such as the construction of 4G networks by operators, FTTH, and the "triple network convergence" initiative, as well as national strategies like Internet Plus and Intelligent Manufacturing, the optical cable industry gained significant development opportunities. Furthermore, the demand for optical fibers and cables is expected to surge, creating a market space of hundreds of billions of yuan. The optical fiber and cable industry will be the first sub-sector to benefit from the construction of communication infrastructure and is poised to enter a new developmental phase.

With the continuous advancement of global optical fiber network construction, the demand for PBT as a core material for optical cables is projected to grow at an annual rate of 8%-10%. In particular, in high-end markets such as 5G, FTTR, and submarine optical cables, technological innovation in high-performance PBT and domestic substitution will become key drivers for industry development.

5. Other Fields

In addition to the aforementioned application areas, PBT holds promising prospects in bio-based and medical applications.

• Medical Devices

Bio-compatible PBT, such as HX260HPR from Sabic Innovative Plastics, has passed ISO 10993 certification and can withstand steam sterilization at 121°C. It is used for surgical instrument housings and biodegradable cardiovascular stents. By 2025, the global market size for biodegradable medical devices is expected to reach 12 billion US dollars, with PBT accounting for over 15%.

• Aerospace

Bio-based PBT composites, such as those in aviation temperature-controlled boxes developed by Chinasing Biotech in collaboration with Haier Biomedical, feature lightweight properties (density of 1.31 g/cm³) and can withstand extreme temperatures ranging from -50°C to 120°C. They have obtained airworthiness certification from the Civil Aviation Administration of China and are applied in cold chain logistics.

• Eco-friendly Packaging

Bio-based PBT nonwovens, such as those modified with titanium-based catalysts, are used in food packaging to replace traditional PE. Their compost degradation rate exceeds 90%, meeting the requirements of the European Union's "New Plastic Strategy." By 2025, the global market size for bio-based packaging is expected to surpass 50 billion US dollars, with PBT accounting for 8%.

YINSU Flame Retardant Company offers flame retardant products suitable for PBT, including halogen-free flame retardant agents such as PBT-WL-20M and YS-22E, as well as red phosphorus flame retardant agents like FRP-604H. These products provide excellent flame retardancy while maintaining the mechanical and thermal properties of PBT materials, meeting the safety and performance requirements of various applications. They are widely used in electronics, electrical, automotive, and other fields where flame retardancy is critical for PBT materials.