JPH0416085B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a plastic optical fiber bar cord used for optical fiber bar cords, optical fiber cables, and the like. [Prior Art] Conventionally, inorganic glass optical fibers have been known as optical fibers, which have excellent optical transmission properties over a wide range of wavelengths, but they have poor workability and low bending stress, as well as poor product quality. Because of the high cost, optical fibers based on plastic have been developed and put into practical use. This plastic optical fiber consists of a core layer made of polymers such as polymethyl methacrylate (PMMA) and polycarbonate (PC), which have high flexibility and good light transmission, and a The basic structural unit is a sheath material layer (clad) whose base material is a transparent polymer such as a fluorine-containing polymer with low flexibility. The product forms of these core-clad optical fibers include bulk fibers such as optical fibers, optical fibers coated with a functional protective layer, and optical fibers. Examples include optical fiber barcodes coated with a jacket material, optical fiber cables that combine bulk fibers, and aggregate fibers that are aggregates of bulk fibers with tension members and the like. Low-density polyethylene, ethylene-vinyl acetate copolymers, etc. have been used as coating materials for optical fiber barcodes and as base materials for protective layers of optical fiber cores, but these polymers have low softening points and low heat resistance. Because of this, it has the disadvantage that it cannot withstand use in high-temperature areas such as the engine room of a vehicle. Therefore, an optical fiber was devised in which heat resistance was imparted by coating the outer layer with a water-crosslinkable polyolefin having a melt index of about 1 to 3.5. However, depending on the coating processing temperature of the water-crosslinkable polyolefin, Due to the orientation strain, the water-crosslinkable polyolefin layer contracts at room temperature, causing the problem that the bulk fiber core protrudes visually. Although it is possible to suppress the orientation strain of the water-crosslinkable polyolefin by increasing the coating processing temperature, it has the drawback of causing thermal deterioration of the fiber core.
Further, it is not preferable to suppress the coating processing speed because productivity decreases. [Means for Solving the Problems] The present invention solves the above-mentioned problems, and provides a plastic optical fiber having a core-sheath structure with a melt index (190°C, 2.16 kg) of 5 or more.
A plastic optical fiber barcode with a jacket layer of water-crosslinkable polyolefin. As a base material for the core of a plastic optical fiber having a core-sheath structure, an amorphous transparent polymer is suitable, such as a homopolymer or copolymer of methyl methacrylate. Preferably, the copolymer contains 70% by weight or more of the starting monomers of methyl methacrylate and 30% by weight or less of the starting monomers of monomers copolymerizable with methyl methacrylate. Examples of monomers copolymerizable with methyl methacrylate include vinyl monomers such as methyl acrylate and ethyl acrylate. Other polymers used as the core base material include cyclohexyl methacrylate, t-butyl methacrylate, isobornyl methacrylate, adamantyl methacrylate,
Benzyl methacrylate, phenyl methacrylate,
Copolymers of methacrylic esters such as naphthyl methacrylate and monomers copolymerizable with these;
Examples include polycarbonate, polystyrene, styrene-methacrylate copolymers, and deuterated polymers in which all or some of the hydrogen atoms of these polymers are replaced with deuterium atoms. As the base material of the cladding, a substantially transparent polymer having a refractive index that is 0.01 or more lower than the refractive index of the core component is used, but usually the difference in refractive index from the core component is in the range of 0.01 to 0.15. It is preferable to choose from. There is no particular restriction on the type of polymer constituting the cladding. For example, when a homopolymer or copolymer of methyl methacrylate is used as the core material, Japanese Patent Publication No. 43-8978, Japanese Patent Publication No. 56-8321,
Special Publication No. 56-8322, Special Publication No. 56-8323 and Japanese Patent Publication No. 1983
Polymerized esters of methacrylic acid and fluorinated alcohols as disclosed in Japanese Patent No. 53-60243 and the like can be used. Further, when polycarbonate or polystyrene is used as the core material, for example, polymethyl methacrylate can be used as the sheath material. Other examples of sheath materials include, for example,
Vinylidene fluoride polymers, vinylidene fluoride-hexafluoropropylene copolymers, methacrylic acid ester polymers other than polymethyl methacrylate, and methylpentene polymers described in Japanese Patent Publication No. 53-42260, etc. Copolymers of esters made of α-fluoroacrylic acid and fluorinated alkyl alcohol, etc. are used. The water-crosslinkable polyolefin used in the present invention has a melt index (190°C, 2.16 kg) of 5.
20 or above and less than 20. If the melt index is less than 5, the orientation will be greatly distorted during the coating process of the jacket material, and if the processing temperature is raised to suppress the orientation distortion, thermal deterioration of the fiber core will occur. Furthermore, if a material with a melt index of 20 or more is used, the jacket material will have extremely low strength, resulting in inconvenience in use. Generally, the melt index of polyethylene for electric wire coating is 0.1 to 3.5, but in the case of water-crosslinkable polyolefin, its strength is increased by post-crosslinking, so there is no practical problem with melt index of 5 or more but less than 20. do not have. Such water-crosslinkable polyolefins contain -Si-
Types that crosslink by forming O-Si- bonds are common, and commercially available water-crosslinkable polyethylene or water-crosslinkable polypropylene such as Linkron and Linkron-X manufactured by Mitsubishi Yuka Co., Ltd. can be used. can. Base polymers for water-crosslinkable polyolefins include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, isotactic polypropylene, and copolymers, block copolymers, and blends thereof. used. The method for manufacturing the plastic optical fiber of the present invention involves spinning only the core or spinning the core and cladding together to shape the fiber, and if necessary, interposing a tension member to add water to the shaped product. A method of coating the crosslinkable polyolefin jacket layer and optionally other constituent layers is used. In addition to water-crosslinkable polyolefin, the jacket layer contains anti-aging agents, carbon black, talc,
Inorganic or organic fillers such as glass fibers, aromatic polyamide fibers, carbon fibers, etc. can also be filled. The structure of the optical fiber barcode of the present invention will be explained with reference to the drawings. 1 to 6 are cross-sectional views showing the structure of the plastic optical fiber barcode of the present invention. FIG. 1 shows an optical fiber in which the outer layer of a core-clad optical fiber (optical fiber wire) consisting of a core layer 1 and a sheath layer 2 is coated with a jacket layer 3 made of water-crosslinkable polyolefin. It is a code. FIG. 2 shows an optical fiber cord having basically the same structure as the example shown in FIG. 1, but with an increased thickness of the jacket layer 3 of water-crosslinkable polyolefin. In Figure 3, a functional protective layer 4 made of other thermoplastic resin such as polymethyl methacrylate or polycarbonate or thermosetting resin such as silicone rubber is provided on the outer peripheral surface of the optical fiber wire, and this is further water-crosslinked. The optical fiber bar code is coated with a jacket layer 3 of polyolefin. FIG. 4 basically has the same configuration as the example shown in FIG. 3, but an appropriate number of steel, FRP, etc. This is an optical fiber bar code in which a section member 5 is arranged. The shape, location, number, etc. of the tension member 5 are not limited to the illustrated example, and can be arbitrarily determined as desired. 5 has basically the same configuration as the example shown in FIG. 3, but a moisture-proof layer 6 is added along the outer peripheral surface of the protective layer 4 by wrapping with a thin metal plate such as aluminum foil or by metal plating. This is an optical fiber barcode installed. FIG. 6 shows an assembled fiber in which a plurality of cores 1, 1 are sequentially covered with a cladding 2 and a jacket layer 3 of water-crosslinkable polyolefin, and is used as an optical fiber bar code or the like. FIG. 7 shows an optical fiber cable in which a plurality of optical fiber bar codes as shown in FIG. 1 are bundled together and combined with a tension member 5. Example 1 The core material layer is polycarbonate with a diameter of 900 μm, and the sheath material layer is methacrylic acid-2,2,3, with a thickness of 10 μm.
A three-layered plastic optical fiber core consisting of a copolymer of 3,3-pentafluoropropyl and methacrylic acid and a protective layer of polycarbonate with a thickness of 40 μm was used, and a crosshead cable processing machine was used to create water-crosslinkable polyethylene [density 0.945g/ ^cm3 ,
Melt index 7.3g/10 minutes (190℃, 2.16
Kg)] was coated at a resin temperature of 160℃ and a linear speed of 50m/min.
An optical fiber bar cord with an outer diameter of 2.2 mm was produced by coating to a thickness of 0.6 mm, and then immersed in hot water at 98°C for 3 hours to perform water crosslinking treatment. The transmission performance of the optical fiber cord obtained in this way after cable processing, the amount of protrusion of the core wire on the end surface of the 5 m cord at room temperature, and the change in appearance after being bent 3000 times at 180 degrees on a 10 mm mandrel were measured. The results are shown in the table below. Example 2 Water-crosslinkable polyethylene coating resin temperature 200
An optical fiber barcode was prepared under the same conditions as in Example 1 except that the temperature was changed to .degree. C., and the same evaluation was performed. The results are shown in the table below. Comparative example 1 Melt index 1.5g/10 minutes (190℃, 2.16
An optical fiber barcode was prepared using water-crosslinkable polyethylene of Kg) under the same conditions as in Example 1, and the same evaluation was performed. Comparative example 2 Melt index 1.5g/10 minutes (190℃, 2.16
An optical fiber barcode was prepared using water-crosslinkable polyethylene of Kg) under the same conditions as in Example 2, and the same evaluation was performed. Comparative example 3 Melt index 23g/10 minutes (190℃, 2.16
An optical fiber barcode was prepared using water-crosslinkable polyethylene of Kg) under the same conditions as in Example 2, and the same evaluation was performed.

[Table] ○: No change
×: Craze occurs at the bent part

[Brief explanation of drawings]

1 to 6 are cross-sectional views of optical fiber bar codes of various structures according to the present invention, and FIG. 1 shows a core clad type optical fiber (optical fiber strand).
Fig. 2 shows a case in which the jacket layer is thicker than that in Fig. 1, and Fig. 3 shows a case in which a functional protective layer is provided on the outer peripheral surface of the optical fiber. is further covered with a jacket layer of water-crosslinkable polyolefin, Fig. 4 shows the optical fiber bar code shown in Fig. 3 with a tension member arranged on the outer circumferential surface of the functional protective layer, and Fig. 5 shows the structure shown in Fig. 3. A moisture-proof layer is provided on the outer surface of the functional protective layer of an optical fiber barcode. Figure 6 shows an optical fiber code with multiple cores. Figure 7 shows a combination of multiple optical fiber barcodes and a tension member. Symbol 1 in the diagram
2 is a core, 2 is a cladding, 3 is a water-crosslinkable polyolefin jacket layer, 4 is a functional protective layer, 5 is a tension member, and 6 is a moisture-proof layer.

Claims (1)

[Claims] 1. A core-sheath plastic optical fiber with a melt index (190°C, 2.16 kg) of 5 or more 20
A plastic optical fiber barcode with a jacket layer of water-crosslinkable polyolefin. 2. The plastic optical fiber bar code according to claim 1, wherein the water-crosslinkable polyolefin is water-crosslinkable polyethylene.