After years of development, the manufacturing technology of optical cables has become very mature. In addition to the well-known characteristics of large information capacity and good transmission performance, optical cables are also required to have the advantages of small size and light weight. These characteristics of the optical cable are closely related to the performance of the optical fiber, the structural design of the optical cable and the manufacturing process, and are also closely related to the various materials and properties that constitute the optical cable.
In addition to optical fibers, the main raw materials in optical cables include three categories:
1. Polymer material: tight tube material, PBT loose tube material, PE sheath material, PVC sheath material, filling ointment, water blocking tape, polyester tape
2. Composite material: aluminum-plastic composite tape, steel-plastic composite tape
3. Metal material: steel wire
Today we talk about the characteristics of the main raw materials in the optical cable and the problems that are prone to occur, hoping to be helpful to the optical cable manufacturers.
1. Tight tube material
Most of the early tight tube materials were use of nylon. The advantage is that it has certain strength and wear resistance. The disadvantage is that the process performance is poor, the processing temperature is narrow, it is difficult to control, and the cost is high. At present, there are more high-quality and low-cost new materials, such as modified PVC, elastomers, etc. From the development point of view, flame retardant and halogen-free material are the inevitable trend of tight tube materials. Optical cable manufacturers need to pay attention to this.
2. PBT loose tube material
PBT is widely used in the loose tube material of optical fiber due to its excellent mechanical properties and chemical resistance. Many of its properties are closely related to molecular weight. When the molecular weight is large enough, the tensile strength, flexural strength, impact strength are high. In actual production and use, attention should be paid to controlling the pay-off tension during cabling.
3. Filling ointment
The optical fiber is extremely sensitive to OH–. Water and moisture will expand the micro-cracks on the surface of the optical fiber, resulting in a significant decrease in the strength of the optical fiber. The hydrogen generated by the chemical reaction between the moisture and the metal material will cause the hydrogen loss of the optical fiber and affect the quality of the optical fiber cable. Therefore, hydrogen evolution is an important indicator of ointment.
4. Water blocking tape
The water blocking tape uses an adhesive to adhere the water-absorbent resin between the two layers of non-woven fabrics. When water penetrates into the inside of the optical cable, the water-absorbent resin will quickly absorb water and expand, filling the gaps of the optical cable, thereby preventing water from flowing longitudinally and radially in the cable. In addition to good water resistance and chemical stability, the swelling height and water absorption rate per unit time are the most important indicators of water blocking tape
5. Steel plastic composite tape and aluminum plastic composite tape
The steel plastic composite tape and aluminum plastic composite tape in the optical cable are usually longitudinal wrapping armored with corrugated , and form a comprehensive sheath with the PE outer sheath. The peel strength of the steel tape/aluminum foil and the plastic film, the heat sealing strength between the composite tapes, and the bonding strength between the composite tape and the PE outer sheath have a great influence on the comprehensive performance of the optical cable. Grease compatibility is also important, and the appearance of the metal composite tape must be flat, clean, free of burrs, and free from mechanical damage. In addition, since the metal plastic composite tape must be longitudinally wrapped through the sizing die during production, the thickness uniformity and mechanical strength are more important to the optical cable manufacturer.