JPS61137112A - Plastic optical fiber cable superior in wet heat resisting characteristics - Google Patents

Abstract

PURPOSE:To enhance wet heat resisting characteristics by forming an electron beam-bridgeable resin coating layer on the surface layer of a plastic optical fiber core. CONSTITUTION:The electron beam-bridgeable resin coating layer 2 is formed on the outer surface of the plastic optical fiber 1. The layer 2 is manufactured by irradiating electron beams on an electron beam-self bridgeable thermoplastic resin, such as low-melting polyethylene, or a thermoplastic resin contg. an electron beam-bridgeable monomer, such as multifunctional monomer. Electron beam irradiation conditions are set to acceleration voltage and irradiation quantity so as to enhance wet heat resistance without deteriorating light transmittance of the plastic optical fiber, thus permitting such characteristics to be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a plastic optical fiber cable with excellent moisture and heat resistance properties.

[Prior art] In general, both optical fibers made of glass and plastic acid have problems in heat and humidity resistance, bending resistance, abrasion resistance, heat and humidity resistance, etc. Therefore, the optical fiber is integrally coated with thermoplastic resin around the optical fiber. It is used in the form of a standardized cable. In particular, in the case of plastic optical fibers, there are concerns about damage and adverse effects from heat, so when making cables, there is a restriction that the fibers must be coated with a thermoplastic resin that can be extruded at low temperatures. Therefore, the thermoplastic resin is generally low melting point polyethylene, and a cable using this resin is a plastic optical fiber cable disclosed in Japanese Patent Application Laid-Open No. 59-9603 by the present applicant.

[Problems to be Solved by the Invention] However, the above-mentioned plastic optical fiber cables have a drawback in terms of moisture and heat resistance, and a moisture and heat resistant plastic optical fiber cable suitable for applications that require high moisture and heat resistance, such as automotive wiring, has been developed. development was requested. It is an object of the present invention to provide a highly practical heat-and-moisture resistant plastic optical fiber cable that solves these conventional problems.

[Means for Solving the Problems] The plastic optical fiber cable of the present invention is characterized in that an electron beam crosslinked resin coating layer is formed on the surface layer of the plastic optical fiber/core wire, and is moisture resistant. The present invention provides an optical fiber cable with significantly improved thermal properties.

Generally, it is a well-known technique to improve the heat resistance of electric wire coatings made of metal conductors (e.g., polyethylene) by irradiating them with electron beams, but directly irradiating plastic or optical fibers with electron beams is not a good technique. Since the core is polymethyl methacrylate, which is a polymer that breaks down by main chain cleavage when exposed to electron beam irradiation, monochain cleavage occurs, resulting in poor thermal and mechanical properties and poor optical transparency. It was considered a difficult technology and had not been implemented.

However, the present inventors coated a plastic optical fiber with a specific thermoplastic resin, and the electric current was
When irradiated with radiation, the plastic optical fiber described in -1- shows no deterioration in light transmittance and its moisture and heat resistance is significantly improved.
We have discovered that this is the case, and have arrived at the present invention.

Hereinafter, the plastic optical fiber cable of the present invention will be explained with reference to the drawings.

The drawing is a cross-sectional view showing an example of a plastic optical fiber cable with excellent moisture and heat resistance according to the present invention, in which an electron beam crosslinked resin coating layer (2) is formed on the outer periphery of a plastic optical fiber (1).
is formed.

The electron beam crosslinked resin coating layer of the present invention is produced by irradiating an electron beam self-crosslinkable thermoplastic resin or a thermoplastic resin containing an electron beam crosslinkable monomer with an electron beam. Specific examples of the above-mentioned electron beam self-crosslinking thermoplastic resin include polyethylene, polyvinylidene fluoride, ethylene-vinyl acetate copolymer, etc.; It is necessary that the material can be extruded at a low temperature when it is made into a cable, and it must not cause the problem of migration of additives such as plasticizers to plastic optical fibers, and low-melting point polyethylene is preferred. Examples of electron beam crosslinkable molecules include a wide variety of polyfunctional molecules.

Examples of polyfunctional monomers include bifunctional monomers that have a side chain (CH3) in the main chain (branched bifunctional monomers), bifunctional monomers that have a linear side chain (CH3), and bifunctional monomers that have a linear side chain (CH3) in the main chain. There are difunctional monomers), and trifunctional monomers 1,
The crosslinking promoting effect is in the following order: S-functional monomer>branched bifunctional monomer>straight chain bifunctional monomer. Examples of the trifunctional toner 1- include [-rimethylolpropane triacrylate, pentaerythritol hexaacrylate, and 1,2,4-trimelin llI allyl ester.

Regarding the electric R-ray irradiation conditions, plastic optical fibers showed a significant improvement in moisture and heat resistance without deterioration in optical transparency.
We found the accelerating voltage and irradiation dose.

As mentioned above, the present invention provides a plastic optical fiber cable having high heat and humidity resistance, and makes it possible to irradiate the plastic optical fiber cable with an electron beam, which has been considered difficult in the past.

[Example] Hereinafter, as an example of the present invention, a prototype plastic optical fiber cable and its heat and humidity resistance evaluation results will be described.

The optical fiber is a plastic optical fiber manufactured by Ichimitibishi Rayon Co., Ltd. (3-layer structure in which a core of polymethyl methacrylate is surrounded by a thin sheath of special fluororesin, and the surrounding area is protected with polymethyl methacrylate), and is 1 m + wφ (Ess. EXTRA EK-40 (trade name) was used as an electron beam self-crosslinking thermoplastic resin for coating, made by Nippon Unicar Co., Ltd. as a thermoplastic resin containing high-pressure process low-density polyethylene, uniball process polyethylene, and electron beam crosslinking type monomer. A cable was manufactured using electron beam crosslinked polyethylene NUC9022.

The manufacturing conditions are: when the coating resin is high-pressure low-density polyethylene and NUC902,2, the processing speed is 30 mmZ, the resin extrusion temperature is 140°C, and the extrusion screw rotation speed is 27 rpm.
The Nimble has a hole diameter of 1.15 mwφ, and the die has a hole diameter of 2.
211IIIφ was used. In the case of uniball low density polyethylene, the processing speed is 30+u++/min.
Resin extrusion temperature 150℃, extrusion screw rotation speed 23 r
pm, the nipple used had a hole diameter of 1.2 mmφ, and the die used had a hole diameter of 2.2 mmφ.

These cables were subjected to electron beam irradiation using an electron beam irradiation device EPS manufactured by Shin High Voltage Co., Ltd. at an acceleration voltage of 300 KV and a beam of 1 ton to 50 Mrad to obtain cables.

The light transmission current value of these cables before and after electron beam irradiation is L
The results of the comparison are shown in Table 1.

The light source for measuring the amount of light is a red light emitting diode,
A photodiode was used as the light receiving section.

From this result, it was confirmed that the effect of electron beam irradiation at a dose of 1 to 50 Mrad on the light transmittance was relatively small, and there was no particular problem.

Next, from these results, a dose of 20.30.35 Mrad was selected as a condition, and the cables irradiated with the electron beam and the cables that were not irradiated with the electron beam were placed in a constant temperature and humidity chamber at 85°C x 95%.
R) (The samples were left to stand under the following conditions, and changes in light transmission current values were measured. The results are shown in Table 2.

Margins below Table 1 Table 2 (Sample length: 12 m, moist heat treatment length: 10 m) From these results, it was confirmed that the plastic optical fiber cable irradiated with an electron beam had excellent moist heat resistance performance. However, at an electron beam irradiation dose of 35 Mrad, the light intensity retention rate tends to decrease slightly, and the appropriate irradiation dose is preferably less than 35 Mrad at an accelerating voltage of 300 KV (7).

This irradiation effect is thought to be due to the fact that crosslinking improves the strength of the coating layer, and at the same time improves the ability to inhibit the permeation of water molecules, and at the same time prevents the plastic optical fiber from shrinking due to moist heat.

[Effects of the Invention] The plastic optical fiber cable of the present invention has excellent heat-and-moisture resistance and can be used in applications requiring high heat-and-moisture resistance.

[Brief explanation of the drawing]

The drawing is a cross-sectional view of the plastic optical fiber cable of the present invention. 1 Niblast optical fiber

Claims (1)

[Claims] A plastic optical fiber cable with excellent moisture and heat resistance, characterized by an electron beam crosslinked resin coating layer formed on the surface layer of a plastic optical fiber core.