JPS63106613A - Plastic optical fiber cord - Google Patents

Abstract

PURPOSE:To improve the heat resistance of a plastic optical fiber cord and to retard the strain of orientation in the stage of coating work by providing a jacket layer comprising specified water-crosslinkable polyolefin on the plastic optical fiber having a core-clad structure. CONSTITUTION:An external layer of core-clad type optical fiber (optical fiber filament) constituted of a core material layer (core 1) and clad material layer (clad 2) is covered by a jacket layer 3 comprising water-crosslinkable polyolefin. The polyolefin crosslinked with water has >=5 and <20 melt index (at 190 deg.C, 2.16kg). The polymer generally used as the above-mentioned polyolefin is the polyethylene or polypropylene which is crosslinkable by the formation of inter- molecular -Si-O-Si linkages due to the condensation reaction between water or the like and the alkoxysilane groups grafted or copolymerized to the principal chain thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic optical fiber cord used for optical fiber cords, optical fiber cables, and the like.

[Conventional technology]

Conventionally, inorganic glass optical fibers have been known as optical fibers that have excellent optical transmission properties over a wide range of wavelengths, but they are not only difficult to process and have low bending stress, but also are expensive, so plastics have not been used. Optical fibers used as base materials have been developed and put into practical use. This plastic optical fiber consists of a core layer made of a polymer such as polymethyl methacrylate (PMMA) or polycarbonate (PC), which has a high refractive index and good light transmittance, and Also, the basic structural unit is a sheath material layer (cladding) whose base material is a transparent polymer such as a fluorine-containing polymer with a low refractive index. The product forms of these core-clad optical fibers (optical fiber wires) are as follows:
This optical fiber wire, bulk fiber such as optical fiber core wire coated with a functional protective layer of optical fiber wire,
Examples include optical fiber cords in which optical fibers are coated with sheathing materials (jacket materials), and optical fiber cables in which bulk fibers or bulk fiber aggregates (teal aggregate fibers) are combined with tension members and the like. Low-density polyethylene, ethylene-vinyl acetate copolymers, etc. have been used as coating materials for these optical fiber cords and as base materials for protective layers of optical fiber cores, but these polymers have low softening points and are not heat resistant. Therefore, it has the disadvantage that it cannot withstand use in high-temperature areas such as the engine room of a vehicle. Therefore, Hikari 7 Eyeper was devised by coating the outer layer with a water-crosslinkable polyolefin with a melt index of about 1 to 3.5, giving it more heat resistance. Due to the orientation distortion, the water-crosslinkable polyolefin layer shrinks at room temperature, causing the problem that the bulk fiber core protrudes in appearance.

Although it is possible to suppress the orientation strain of the water-crosslinkable polyolefin by raising the coating processing temperature, it has the disadvantage 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.
This is a plastic optical fiber cord in which a jacket layer of water-crosslinkable polyolefin having a melt index (190° C., 2.16 kF) of 5 or more and less than 20 is provided on a plastic optical fiber having a sheath structure.

A non-grade transparent polymer is suitable as a base material for the core layer of a plastic optical fiber with a core-sheath structure.
For example, a homopolymer or copolymer of methyl methacrylate is used. In the copolymer, 70% by weight or more of the starting monomer is preferably methyl methacrylate, and 30% by weight or less is a monomer copolymerizable with methyl methacrylate.

Monomers copolymerizable with methyl methacrylate include:
Examples include vinyl monomers such as methyl acrylate and ethyl acrylate. Other polymers used as the core base material include methacrylic acid esters such as cyclohexyl methacrylate, 1-butyl methacrylate, isobornyl methacrylate, adamantyl methacrylate, benzyl methacrylate, phenyl methacrylate, and naphthyl methacrylate; copolymers with copolymerizable monomers, polycarbonate, polystyrene, styrene-methacrylic acid ester copolymers, or deuterated polymers in which all or some of the hydrogen atoms of these polymers are replaced with deuterium atoms. etc. can be mentioned.

As a base material for the cladding, the refractive index is 0.0 lower than that of the core component.
A substantially transparent polymer having a refractive index less than 1 is used, but typically the difference in refractive index from the core component is 0.01.
It is preferable to select from those in the range of ~0.15. There is no particular restriction on the nine types of polymers 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, It is possible to use polymerized esters of methacrylic acid and fluorinated alcohols as disclosed in Japanese Patent Publication No. 1973. 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, and methacrylic acid ester polymers other than polymethyl methacrylate, which are described in No. 5-8978, Japanese Patent Publication No. 56-42260, etc. A methylpentene polymer, a copolymer 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 (9 at 190°C, 2,167) of 5 or more and 2
It is less than 0. If the melt index is less than 5, the orientation strain during coating with the jacket material will be large, and if the processing temperature is raised to suppress the orientation strain, 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, the strength is increased by post-crosslinking, so it is practical to use a melt index of 5 or more and less than 20. No problem. Such water-crosslinkable polyolefins are generally of the type in which an alkoxysilane grafted or copolymerized to a polyethylene or polypropylene chain reacts with water, etc., and forms a -8i-0-8i-bond through condensation and crosslinks. Commercially available water-crosslinkable polyethylene or water-crosslinkable polypropylene such as Linkron and Linkron-X manufactured by Mitsubishi Yuka Co., Ltd. can be used. As the base polymer for water-crosslinkable polyolefin, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, tactical polypropylene, as well as their copolymers, block copolymers, blends, etc. are used. It will be done.

The method for manufacturing the plastic optical fiber of the present invention involves spinning only the core or spinning a core and a cladding together to form the formed product, and adding a water-crosslinkable polyolefin to the formed product by interposing a tension member as necessary. A method of coating the jacket layer and other constituent layers as desired is used.

In addition to the water-crosslinkable polyolefin, the jacket layer can also be filled with inorganic or organic fillers such as anti-aging agents, carbon black, talc, glass fibers, aromatic polyamide fibers, and carbon fibers.

The structure of the optical fiber cord 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 cord of the present invention. Figure 1 shows a core-clad optical fiber (optical fiber strand) consisting of a core layer (core) 1 and a sheath layer (cladding) 2.
This is an optical fiber cord coated with a jacket layer 3 of a single-layer water-crosslinkable polyolefin. 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.

Figure 3 shows that a functional protective layer 4 made of a thermoplastic resin such as polymethyl methacrylate or polycarbonate or a thermosetting resin such as silicone rubber is provided on the outer circumferential surface of an optical fiber wire. This is an optical fiber cord coated with a jacket layer 3 of crosslinkable polyolefin. FIG. 4 basically has the same configuration as the example in FIG. 3, but an appropriate number of tension members made of steel, FRP, etc. are placed at appropriate locations within the fiber, for example, along the outer peripheral surface of the protective layer 4. This is an optical fiber cord in which 5 is arranged. The shape, location, number, etc. of the tension members 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. 6, but a moisture-proof layer 6 is provided 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 cord.

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 cord or the like.

FIG. 7 shows an optical fiber cable in which a plurality of optical fiber cords as shown in FIG. 1 are bundled together and combined with a tension member 5.

Example 1 The core layer is polycarbonate with a diameter of 900 μm, the sheath layer is a copolymer of 2,2,3,3,3-pentafluoropropyl methacrylate and methacrylic acid with a thickness of 10 μm, and the protective layer is polycarbonate with a thickness of 40 μm. Using a three-layer plastic optical fiber core wire, water-crosslinkable polyethylene [density 0
．． 945 i/err? , melt index 7.
Coating processing was carried out for 3,9710 minutes (190°C, 2.16 kp) at a resin temperature of 160°C and a linear speed of 50 TL/min to a thickness of 0.6 in order, and an optical fiber cord with an outer diameter of 2.2 mm was manufactured. Then, it was 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 fiber protrusion on the end face at room temperature in a 5 m cord, and the 180 degrees on the 10111 mandrel.
Changes in appearance after bending 3000 times were measured. The results are shown in the table below.

Example 2 An optical fiber cord was prepared under the same conditions as in Example 1 except that the temperature of the water-crosslinkable polyethylene coating resin was changed to 200° C., and the same evaluation was performed. The results are shown in the table below.

Comparative Example 1 Melt index 1.5 g/10 minutes (190°C, 2.
An optical fiber cord was prepared using water-crosslinkable polyethylene of 160 ml and under the same conditions as in Example 1, and the same evaluation was performed.

Comparative Example 2 Melt index is,? /10 minutes (190℃, 2.
An optical fiber cord was prepared using water-crosslinkable polyethylene (16 kP) under the same conditions as in Example 2, and the same evaluation was performed.

Comparative example 3 Meltings 2223g/10 minutes (190℃,.

An optical fiber cord was prepared using water-crosslinkable polyethylene (2.16 kp) under the same conditions as in Example 2, and the same evaluation was performed.

○: No change X: Craze occurs at the bending part

[Brief Description of the Drawings] Figures 1 to 6 are cross-sectional views of optical fiber cords with various structures according to the present invention. The one coated with a jacket layer, the one in Figure 2 has a thicker jacket layer than the one in Figure 1, and the one in Figure 3 has a functional protective layer on the outer peripheral surface of the optical fiber, which is further coated with water-crosslinkable Figure 4 shows the optical fiber cord shown in Figure 6, with a tension member arranged on the outer peripheral surface of the functional protective layer.
The figure shows the optical fiber cord shown in Figure 6 with a moisture-proof layer provided on the outer peripheral surface of the functional protective layer, Figure 6 shows the optical fiber cord with multiple cores, and Figure 7 shows the optical fiber cord with multiple optical fiber cords and a tension member. In the combination, symbol 1 in the figure indicates a core, 2 indicates a cladding, 6 indicates a water-crosslinkable polyolefin jacket layer, 4 indicates a functional protective layer, 5 indicates a tension member, and 6 indicates a moisture-proof layer. Figure 7 Figure 2 Figure 3 Figure 4121 Figure 5 Figure 6 Figure 7

Claims (1)

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