JP2504760B2 - Heat resistant plastic optical fiber - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a heat-resistant plastic optical fiber which has no deterioration of light guiding performance even in an environment exceeding 90 ° C. and has excellent mechanical strength. is there.

(Prior art) Plastic optical fibers are more flexible than silica optical fibers, have a large diameter and high numerical aperture, and are easy to endface process and connect. Short-distance communication and its application to various fields have begun.

The plastic optical fiber that has been put to practical use has
The core material is a copolymer mainly composed of methyl methacrylate, vinylidene fluoride-tetrafluoroethylene copolymer or a sheath material using a fluorinated methacrylate copolymer, or polystyrene as the core material, For example, there is a sheath material made of polymethylmethacrylate. However, in the former case, the glass transition point of the core material, polymethylmethacrylate, is about 10
Since it is 5 ° C, the latter has a glass transition point of polystyrene, which is the core material, of about 100 ° C.
It can be used only under the environment.

On the other hand, as a plastic optical fiber having a heat resistance of 100 ° C. or more, one using a polycarbonate having a glass transition point of about 150 ° C. as a core material is considered. As the sheath material, there are 4-methylpentene-1, fluorinated methacrylate-based copolymer, and fluorescein of the Institute of Electrical Communication of Japan in 1985, JP-A-60-32004, JP-A-61-6604, and JP-A-61-22313. Vinylidene chloride-based copolymers and the like are disclosed. However, none of them have any adhesiveness to the core material, polycarbonate, so that the heat resistance is not sufficient and the mechanical properties are remarkably deteriorated.

In this way, the plastic optical fiber, which has been considered in the past, does not have sufficient heat resistance and mechanical properties, so it must be installed in the engine room of automobiles / ships and at high temperatures, and used for optical communication waveguides and optical sensors. It has not reached the point where it can be used as.

(Problems to be Solved by the Present Invention) The present invention has extremely good adhesion between the core material and the sheath material, not only has excellent heat resistance only by the two-layer structure of the core / sheath but also has low loss. The present invention provides a heat resistant plastic optical fiber having a high numerical aperture and excellent mechanical properties.

(Means for Solving the Problem) In order to solve the above-mentioned problems, the present inventors have
As a result of earnest research, the present invention has been reached. That is, the present invention uses a polycarbonate as a core material and a perfluoroacetone structural unit represented by the following structural formula (I) as a sheath material in an amount of 1% by weight or more and 30% by weight or less, and a melt index of 10 ( A heat-resistant plastic optical fiber using a resin composition having a load of 3.8 kg or more.

Structural formula (I) As a polycarbonate suitable for the core material, the general formula And R is An aliphatic polycarbonate represented by An aromatic polycarbonate represented by
In addition, copolymers of these with dioxy compounds such as 4,4-dioxyphenyl ether, ethylene glycol, p-xylene glycol, and 1,6-hexanediol, and hetero compounds having ester bonds in addition to carbonate bonds. A bond copolymer or the like can also be used.

A transparent resin having a smaller refractive index than the core material is used for the sheath material. The core material, polycarbonate, has a refractive index of 1.58.
Since it is relatively large, various transparent resins have been considered so far. But each has its drawbacks.

For example, a methylpentene-based copolymer has high transparency and a high glass transition point, but has no adhesiveness with polycarbonate. Further, polymethylmethacrylate has good weatherability and adhesiveness, but its refractive index is 1.49, so the numerical aperture is not large. In order to increase the numerical aperture, when using a fluorinated methacrylate-based copolymer or a vinylidene fluorinated-based copolymer with a refractive index of about 1.40, since there is no adhesiveness with the polycarbonate at all, core-sheath peeling occurs just by bending a little. However, it loses the characteristic of plastic optical fiber, which is excellent in flexibility.

In the present invention, the refractive index is sufficiently low, excellent mechanical properties,
Moreover, as a sheath material with good adhesion to polycarbonate,
Vinylidene fluoride-hexafluoroacetone copolymer,
Vinylidene fluoride-tetrafluoroethylene-hexafluoroacetone copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropene-hexafluoroacetone copolymer, other, blends of these copolymers and polymethylmethacrylate, and , And blends of these copolymers with fluoroalkyl methacrylate-based copolymers. All of them adhere well to polycarbonate and do not lose their advantages if they have excellent mechanical properties characteristic of vinylidene fluoride sheath.

What is important here is that hexafluoroacetone is contained at least 1.0% by weight or more and 30% by weight or less as a monomer of the sheath material which is a copolymer. The proportion of the remaining monomer can be appropriately selected.

On the other hand, in order to have good performance as a plastic optical fiber, the interface between the core and the sheath must be smooth and smooth. To do this, the melt index of the sheath material (ASTM-1238, test temperature 230 ℃, load 3.8Kg, die inner diameter 2.0
955mm) must be at least 2g / 10 minutes or more. It is preferably 20 (load 3.8 kg) or more. If the melt index is less than this range, the core-sheath interface and fiber surface will not be smooth.

As a method for producing the plastic optical fiber of the present invention, a so-called composite spinning method is used in which the pellets of the core material and the sheath material are melted in a clean environment and a core-sheath structure is formed by a special nozzle and an extruder. Is the best. The thickness of the sheath covers from 2/1000 to 300/1000 of the diameter of the core,
Get a bare wire. This bare wire includes cross-linked polyethylene, cross-linked vinyl, polypropylene, polyvinylidene florafide,
Heat resistant coating such as nylon is put into practical use as a cord.

 Specific examples will be shown below.

(Example 1) Panlite, a trade name of Teijin Kasei Co., Ltd., was used for the polycarbonate of the core material. A hexafluoroacetone-vinylidene fluoride-tetrafluoroethylene copolymer (monomer weight ratio 13:72:15) was used as the sheath material. Each physical property value is as follows.

(Melt index) 30g / 10mm (Refractive index) 1.395 (Adhesiveness) Polycarbonate is molded into a plate with a thickness of 3mm, which is then pressure-bonded with a sheath film (thickness 50 to 300μm) press. Then, make cuts with a razor in a grid pattern at 1 mm intervals, and attach cellophane tape from above. When I peeled it off,
The number of peeled pieces out of 100 pieces is counted, and the adhesiveness is evaluated by the ratio.

Peeling rate 10% A sheath material pellet having the above physical properties and a commercially available polycarbonate, "Panlite" pellet made by Teijin Kasei Co., Ltd. are melted at 240 ° C, and a composite spinning die and an extruder are used. Thus, the heat-resistant plastic optical fiber of the present invention having a two-layer structure of core / sheath was produced.

The light guiding performance of the obtained plastic optical fiber was 1100 dB / km at an emission wavelength of 770 nm. And the temperature 13
It was placed in a constant temperature room at 0 ° C and changes in light guiding performance were observed. Result is,
In the first 10 days, the light guide performance changed to 1150 dB / km, but after that, it did not change until 30 days.

(Example 2-5) The same plastic optical fiber as in Example 1 was produced except that the composition and physical properties of the sheath material used were changed as shown in Table 1. Table 1 shows the results of evaluation of these plastic optical fibers by the same method as in Example 1.

(Comparative Example) The polycarbonate of the core material is the same as that of Example 1, and the sheath material does not contain hexafluoroacetone, that is, vinylidene fluoride-tetrafluoroethylene copolymer (VT-100 manufactured by Daikin Industries, Ltd.). , Vinylidene fluoride-tetrafluoroethylene-hexafluoropropene copolymer (prototype manufactured by Asahi Kasei Kogyo Co., Ltd., poly-4-methylpentene-1 (TPX manufactured by Mitsui Petrochemical Co., Ltd.)). The adhesiveness was evaluated in the same manner as in Example 1. As a result, the peeling rate of all three was 100%, and no adhesion was observed to the polycarbonate.

(Effect of the present invention) The plastic optical fiber of the present invention has good adhesion between the core material and the sheath material, and has excellent light guide performance, wet heat resistance, and mechanical properties.
Moreover, it has a high numerical aperture. Since the performance does not deteriorate even under severe conditions such as the engine room of automobiles and ships, it can be used for various purposes in various places.

Claims (5)

(57) [Claims] 1. A resin comprising a polycarbonate as a main component, and a sheath material containing 1% by weight or more and 30% by weight or less of a perfluoroacetone structural unit represented by the following structural formula (I) and having a melt index of Structural formula (I) of heat-resistant plastic optical fiber using resin composition of 10 (load 3.8 kg) or more 2. The heat-resistant plastic optical fiber according to claim 1, wherein the sheath material is a copolymer of vinylidene fluoride and hexafluoroacetone. 3. A heat-resistant plastic optical fiber according to claim 1, wherein the sheath material is a copolymer of vinylidene fluoride, tetrafluoroethylene and hexafluoroacetone. 4. A heat-resistant plastic optical fiber according to claim 1, wherein the sheath material is a copolymer of vinylidene fluoride, tetrafluoroethylene, hexafluoropropene and hexafluoroacetone. 5. The melt index of the sheath material is 20 (load 3.8K.
g) The heat-resistant plastic optical fiber according to claim 1, which is not less than g)