| 摘要 |
PURPOSE:To obtain optical fiber cores with low optical attenuation, low water absorbing property and high wear resistance by using crystal polypropylene with a specific melt flow index (MFI) as the outer covering of an optical fiber core which is coated with plural plastic layers. CONSTITUTION:After coating an optical fiber (quartz) with a primary plastic covering (silicons resin or the like) 2, isotactic polypropylene (crystal polypropylene) whose MFI is 3-15g/10min at 230 deg.C 2.16kg and 8 times of the MFI of 230 deg.C at 290 deg.C 2.16kg is used as a secondary plastic covering to coat the primary covering 2. If necessary, a buffer layer 4 is applied between the coverings 2 and 3. The polypropylene with the above-mentioned characteristics has superior workability, making it possible to obtain superior optical fiber cores which are uniformly coated, have no distortion and scars on the covering layers and do not increase optical loss even if temperature and pressure are variously changed. |
