1. Overview
With the rapid development of information and communication technology, optical cables, as the core carrier of modern information transmission, have increasingly higher requirements for performance and quality. Polybutylene terephthalate (PBT), as a thermoplastic engineering plastic with excellent comprehensive performance, plays an important role in the manufacturing of optical cables. PBT is formed by the condensation polymerization of dimethyl terephthalate (DMT) or terephthalic acid (TPA) and butanediol after esterification. It is one of the five general-purpose engineering plastics and was initially developed by GE and industrialized in the 1970s. Although it started relatively late, it has developed extremely rapidly. Due to its excellent comprehensive performance, strong processability and high cost performance, it is widely used in electrical appliances, automobiles, communications, home appliances and other fields. Especially in the manufacturing of optical cables, it is mainly used in the production of optical fiber loose tubes and is an indispensable type of high-performance cable material in the raw materials of optical cables.
PBT is a milky white semi-transparent to opaque semi-crystalline polyester with excellent heat resistance and processing stability. Its molecular structure is [(CH₂)₄OOCC₆H₄COO]n. Compared with PET, it has two more methylene groups in the chain segments, giving its main molecular chain a helical structure and better flexibility. PBT is not resistant to strong acids and strong alkalis, but can resist most organic solvents and will decompose at high temperatures. Thanks to its excellent physical properties, chemical stability and processing performance, PBT has become an ideal structural material in the optical cable industry and is widely used in various PBT products for communication cables and optical cables.
2. Characteristics of PBT Materials
PBT is usually used in the form of modified blends. By adding flame retardants, reinforcing agents and other modification methods, its heat resistance, electrical insulation and processing adaptability can be further improved. PBT has high mechanical strength, good toughness and wear resistance, and can effectively protect the optical fibers inside the optical cable from mechanical stress damage. As one of the common raw materials for optical cables, PBT resin ensures that optical cable products have good flexibility and stability while maintaining structural strength.
Meanwhile, it has strong chemical stability and can resist various corrosive media, ensuring the long-term stable operation of optical cables in complex environments such as humidity and salt spray. PBT material has excellent thermal stability and can maintain stable performance even in high-temperature environments, making it suitable for optical cable applications in different temperature zones. It has excellent processing performance and can be formed by extrusion, injection molding and other methods. It is suitable for optical cable assemblies of different shapes and structures and is a high-performance engineering plastic widely used in cable manufacturing.
3. Application of PBT in Optical Cables
In the process of optical cable manufacturing, PBT is mainly used in the production of loose tubes for optical fibers. Its high strength and toughness can effectively support and protect optical fibers, preventing damage caused by physical factors such as bending and stretching. In addition, PBT material has excellent heat resistance and anti-aging performance, which helps to enhance the stability and reliability of optical cables during long-term operation. It is one of the mainstream PBT materials used in optical cables at present.
PBT is also often used as the outer sheath of optical cables. The sheath not only needs to have a certain mechanical strength to cope with changes in the external environment, but also needs to have excellent wear resistance, chemical corrosion resistance and UV aging resistance to ensure the service life of the optical cable during outdoor laying, in damp or Marine environments. The optical cable sheath has high requirements for the processing performance and environmental adaptability of PBT, and PBT resin shows good application compatibility.
In optical cable joint systems, PBT can also be used to manufacture key components such as joint boxes. These components need to meet strict requirements for sealing, waterproofing and weather resistance. PBT material, with its excellent physical properties and structural stability, is an extremely suitable choice and plays an important structural support role in the optical cable raw material system.
4. Processing Precautions
Before injection molding processing, PBT needs to be dried at 110℃ to 120℃ for about 3 hours to remove the adsorbed moisture and avoid the formation of bubbles or brittleness during the processing. The molding temperature should be controlled between 250℃ and 270℃, and the mold temperature is recommended to be maintained at 50℃ to 75℃. Because the glass transition temperature of PBT is only 22℃ and the cooling crystallization rate is fast, its cooling time is relatively short. During the injection molding process, it is necessary to prevent the nozzle temperature from being too low, which may cause the flow channel to be blocked. If the barrel temperature exceeds 275℃ or the molten material stays for too long, it may cause thermal degradation and embrittlement.
It is recommended to use a larger gate for injection. The hot runner system should not be used. The mold should maintain a good exhaust effect. PBT sprue materials containing flame retardants or glass fiber reinforcement are not recommended to be reused to avoid performance degradation. When the machine is shut down, the barrel should be cleaned in time with PE or PP material to prevent the carbonization of residual materials. These processing parameters have practical guiding significance for optical cable raw material manufacturers in large-scale cable material production.
5. Application Advantages
The application of PBT in optical cables has significantly improved the overall performance of optical cables. Its high strength and toughness enhance the impact resistance and fatigue resistance of the optical cable, and extend its service life. Meanwhile, the excellent processability of PBT materials has enhanced production efficiency and reduced manufacturing costs. The excellent anti-aging and chemical corrosion resistance of the optical cable enable it to maintain stable operation for a long time in harsh environments, significantly enhancing the reliability and maintenance cycle of the product.
As a key category in the raw materials of optical cables, PBT resin plays a role in multiple structural links and is one of the thermoplastic engineering plastics that optical cable manufacturers give priority to when choosing cable materials.
6. Conclusions and Prospects
PBT has become an indispensable important material in the field of optical cable manufacturing due to its outstanding performance in mechanical properties, thermal stability, corrosion resistance and processability. In the future, as the optical communication industry continues to upgrade, higher requirements will be put forward for material performance. The PBT industry should continuously promote technological innovation and green environmental protection development, further enhancing its comprehensive performance and production efficiency. While meeting performance requirements, reducing energy consumption and material costs will help PBT play a more important role in optical cables and a wider range of application fields.
Post time: Jun-30-2025