JPS6269214A - Light transmitting cable - Google Patents

Abstract

PURPOSE:To obtain light transmitting cable having high heat resistance and plasticity by covering strand wire of light transmitting fiber comprising methacrylic resin as core component with a thermoplastic elastomer. CONSTITUTION:The light transmitting cable is prepd. by covering strand wire of light transmitting fiber comprising methacrylate resin as core component with a thermoplastic elastomer. Since the rate of decrease of light transmitting loss in accompany with the elevation of temp. of this light transmitting cable is small in a temp. range between room temp. and ca. 80 deg.C, the reliability of the cable as a light signal transmitting medium is higher. Preferred methacrylic resin to be used for the core component is one contg. methacrylic ester having 8-20C alicyclic hydrocarbon group in the ester moiety. Suitable thermoplastic elastomer is exemplified by olefinic thermoplastic elastomers or esteric thermoplastic elastomers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical transmission cable with excellent heat resistance, which is made by coating optical transmission fiber strands with a resin.

Optical transmission fibers have traditionally been manufactured using glass-based materials, but recently many attempts have been made to make them from plastic.

The major characteristics of using Plasti-I fiber are that it is light in weight, is strong and highly flexible even with a thick W4 fiber inside diameter, and can therefore be made with an aperture of 7 mm and a large diameter, making it suitable for both light receiving and emitting elements. It has excellent operability, such as being easy to connect with.

A common method for manufacturing such optical transmission fibers using plastic is to use a plastic with a large refractive index and good light transmission as a core component, and a plastic with a smaller refractive index than the core material.
Moreover, the fiber has a core-sheath structure in which the sheath component is transparent plastic.

This method transmits light by reflecting it at the core-sheath interface, and the larger the difference in refraction between the core and the sheath, the better the light transmission. ing.

Amorphous materials are preferable as transparent plastics, and polymethyl methacrylate and polystyrene are attracting attention from an industrial perspective (for example,
No. 8978).

However, the transmission loss of such plastic optical transmission fibers decreases as the temperature rises, and the decrease value is large, making them unreliable as optical signal media. Also, when condoling for robots, etc., there are restrictions on the purpose and place of application.

In other words, the upper limit temperature at which polymethyl methacrylate and polystyrene can be used is approximately 80°C; at temperatures higher than that, thermal contraction increases, deformation occurs, and microstructural fluctuations occur, making them unusable as optical fibers. It has disadvantages such as not being able to achieve the tQll of It could only be used in the area. Therefore, there is a need for the development of plastic optical transmission fibers with excellent heat resistance.

In view of the current situation, the present inventors investigated the development of a 1 m plastic optical transmission device with excellent heat resistance and optical transmission properties, and found that the ester moiety contains an alicyclic hydrocarbon group having 8 or more carbon atoms. 8 to 4 O of methacrylic acid ester present
! 11% of methyl methacrylate as a core component, and a transparent resin or fluororubber having a refractive index that is at least 8% smaller than the core component as a sheath component. We discovered and proposed an optical transmission fiber with excellent flexibility.

In order to apply such optical transmission fiber strands to transmission systems, it is necessary to coat the strands with resin to make optical transmission cables, and the coating material conventionally used is generally black polyethylene. Or polyvinyl chloride.

The optical transmission fiber strands previously proposed by the present inventors had satisfactory heat resistance and flexibility, but optical transmission cables coated with black polyethylene or polyvinyl chloride, on the other hand, When used at high temperatures of 110°C or higher, the surface of the wire is likely to be damaged by external stress, causing light to leak from the damaged area and increasing light guide loss, making it unreliable in practice. This was not completely satisfactory as an optical transmission cable.

Therefore, the present inventors have attempted to improve this drawback.
Although an optical transmission cable using a thermoplastic resin with a glass transition temperature or melting point of 120 to 260° C. as a molding material was proposed, there was still room for improvement in terms of flexibility.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to develop a practically reliable optical transmission cable with excellent heat resistance and plasticity.

That is, the present invention relates to methacrylate fruit trees []iI? The present invention relates to an optical transmission cable with excellent heat resistance, which is made by coating a thermoplastic elastomer on a strand of optical transmission fiber having a core component of.

In the optical transmission cable of the present invention, in the temperature range from room temperature to around 80° C., the rate of decrease in light guiding loss that occurs with increasing temperature is small, and its reliability as an optical signal transmission medium can be improved.

Even at temperatures where the previously proposed optical transmission cables coated with black polyethylene or polyvinyl chloride cannot be used, there is almost no decrease in light guide loss.
Also, in terms of flexibility, it is superior to the previously proposed optical transmission cable using the thermoplastic tree 8j.

In the present invention, a methacrylate resin is used as the core component. Among these, those containing a methacrylic acid ester in which the ester moiety has an alicyclic hydrocarbon group having 8 to 20 carbon atoms are preferred.

Methacrylic acid ester having an alicyclic hydrocarbon group having 8 to 20 carbon atoms is methacrylic acid or its acid chloride,
Created by esterification with a cycloaliphatic hydrocarbon monool of formula R (JH).

Alicyclic hydrocarbons, monools include 2゜6-dimethylcyclohexanol, borneol, isoborneol, t-menthol, femethyl alcohol, p-menthanol-2,1-adamantanol, 3-methyl-1
-adamantanol, 8.5-dimethyl-1-adamane2.8-tanol, tricyclo(5,2,1,0)dec-8-ol, etc.! I! ? Examples include R1 hydrocarbons and monools, and corresponding methacrylic esters.

Among these methacrylic acid esters, particularly preferred are fenthyl methacrylate, t-menthyl methacrylate,
Bornyl methacrylate, isobornyl methacrylate, 1-adamantyl methacrylate, methacrylic acid 3.5
-dimethyl-1-adamantyl methacrylate tricyclo! ! l6 (5, 2, 1, 0)] Decal 8-i can be given.

These methacrylic acid esters are 8I! Core components containing less than 40 MNk%, which mainly consist of methyl methacrylate, have excellent regression properties, but do not contribute much to improving heat resistance, and core components containing more than 40 MNk% have poor heat resistance. Although it is excellent, in practical terms, the improvement in flexibility is small. Compared to the case of vi-type hydrogenated group, aromatic hydrocarbon group, and Ig group, the light guide loss in the optical transmission fiber is small, and it can be widely used as an optical signal transmission medium.

In addition to the monocyclic hydrocarbon group having 8 or more carbon atoms, the monocyclic hydrocarbon group having 10 or more carbon atoms has a high contribution rate to improving heat resistance.

When a methacrylic acid ester having an alicyclic hydrocarbon group having 7 or more carbon atoms is used, the heat resistance is not improved much. or,
Even when the number of carbon atoms is 8 or more, linear hydrocarbon groups, for example,
Methacrylic acid esters such as fentyl methacrylate and n-dodecyl methacrylate have little improvement in heat resistance. It tends to be charcoal.

The methacrylate resin used in the present invention has 1 to 4 carbon atoms.
It is possible to contain an alkyl acrylate having an alkyl group by co-merging. In order to maintain heat resistance, the amount of these copolymerized components should be the minimum necessary, and it is desirable to set it to 5% or less. 8 carbon atoms in the ester part
Methacrylic acid ester having ~20 alicyclic carbon groups 8
~40! A polymer containing methyl methacrylate as a main component exhibits a high refractive index, and therefore has desirable properties as a light transmission fiber.

On the other hand, the pod component is less than the core component (both 8%
A transparent resin or fluororubber having a small refractive index is used. If the difference in refractive index is smaller than 8%, the proportion of light reflected by the sheath component will be small and the light guide loss will be large. Specifically, the refractive index is preferably 1.42 or less, and it is desirable that the polymer be a non-crystalline, nearly amorphous polymer and have good adhesion to the core component.

Preferred transparent resins and fluororubbers include fluororesins,
There are thermoplastic fluororubbers and fluororubbers. Examples of the fluororesin include acrylic or methacrylic polymers and copolymers such as fluoroalkyl α-fluoroacrylates, alkyl α-fluoroacrylates, and fluoroalkyl methacrylates, and fluorine-containing olefins containing fluorine-containing olefins. iI! Mention may be made of polymers and copolymers.

The fluoroalkyl α-fluoroacrylate polymer, the alkyl fluoroacrylate, and the fluoroalkyl methacrylate polymer include those whose homopolymer has a softening temperature of about 50°C or higher and a refractive index of 1.48 or lower. preferable.

Examples of the fluorine-containing olefin polymers include vinylidene fluoride-tetrafluoroethylene copolymer, trifluoroethylene-vinylidene fluoride copolymer, and vinylidene fluoride-tetrafluoroethylene-hexafluoropropene copolymer. be able to.

Thermoplastic fluororubber has a soft segment consisting of a fluororesin phase and a hard segment consisting of a fluororesin phase in its molecule, and has rubber elasticity due to physical crosslinking in the fluororesin phase at room temperature. At high temperatures, it has the same behavior as thermoplastic plastics. A typical example is Daiel Thermoplastic (
Daikin Industries, Ltd.) was taken away.

Preferred fluororubbers include vinylidene fluoride-hexafluoropropene copolymer, vinylidene fluoride-pentafluoropropene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and the like. Particularly preferred is vinylidene fluoride-hexafluoropropene copolymer.

The optical transmission edge m wire of the present invention can be manufactured by a conventional known method. In the case of core component polymers, suspension polymerization uses a large amount of water, which makes it easy for foreign substances to get mixed into the polymer, and there is also a possibility that foreign substances can get mixed in during the dehydration process. There is. Depending on the case, it is preferable to perform polymerization after removing foreign substances such as dust by a transient method or distillation method. In addition, a desirable method is to carry out the manufacturing step of the core component 4-combination and the manufacturing step of the optical transmission pongee in a continuous process, and to carry out the continuous bulk polymerization process of the core component polymer at high temperature and subsequent steps. There is a method for producing it in two steps: continuous fractionation of volatiles using the remaining unreacted monochrome as a living body. A manufacturing method in which a core component is bulk polymerized and then a core component and a sheath component are formed from the obtained polymer by double extrusion is also a popular method. In the case of the sheath component polymer, in the case of the core component polymer, the manufacturing method has no effect on optical transmission properties, so make sure that foreign substances such as dust do not get in, and use the transient method if necessary. The sheath component polymer can be produced by removing foreign substances such as dust.

A thermoplastic elastomer is used for -C as a covering for the light transmission fiber foliage, which is a feature of the present invention. Examples of the thermoplastic elastomer include olefin thermoplastic elastomers and ester thermoplastic elastomers. Preferred olefinic thermoplastic elastomers include those in which vulcanized fine particles of EPDM are dispersed in polyolefin, such as Santoblane (manufactured by Monsando Co., Ltd.).
Examples of the ester-based thermoplastic elastomer include polyester in which polybutylene terephthalate is used as a hard segment and aliphatic polyester is used as a soft segment.

An example of a polyester type copolymer is Perbrene (Ityobo R Co., Ltd.).

If necessary, 1 to 30% of carbon black, glass a, talc, calcium carbonate, mica, potassium titanate, etc. can be added to these thermoplastic elastomers.

The method for coating the thermoplastic elastomer on the optical transmission i* element is carried out using an extruder in the same manner as in coating a conventional single wire with a thermoplastic resin.

Since the optical transmission cable of the present invention can have a normal operating temperature of 110° C. or higher, it can be applied to, for example, automobiles, ships, aircraft, robots, and the like. Furthermore, the range of application can be expanded by relaxing temperature conditions for communication within premises and buildings.

Moreover, compared to the case where a thermoplastic resin having a glass transition temperature or melting point of 120 to 260° C. is used as a covering material, it has a characteristic that it has excellent connectability, which is a practically important physical property of an optical transmission cable.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. The light guide loss was measured using a diffraction grating spectrometer using a halogen tungsten lamp as a light source, and reading the output intensities of the measured light transmission fiber and the reference light transmission fiber at a wavelength of 650 nm with a silicon photodiode. The light guide loss α of Ll+) was determined.

Further, the heat resistance test was conducted by heating the obtained optical transmission fiber for a predetermined period of time, and then measuring and comparing the light guide loss at the initial stage and after heating.

Example 1 Monomer purified by vacuum distillation and suspension stabilizer (hydroxyethyl cellulose, 0.08% based on monomer)
, an organic peroxide (lauroyl peroxide, 0.3% based on the monomer), a molecular weight regulator (n-dodecyl mercaptan, 0.16% based on the monomer) and water were filtered through a porous 1 (0.1βmφ). Bornyl methacrylate:Methyl methacrylate:Methyl acrylate=25nia 4:1 (wt%), which was polymerized by suspension polymerization method by blending the obtained product in a nitrogen atmosphere without containing additives, [
[Chloroform, 25 tl:) 0.70. The polymer in the form of a strand with a refractive index diameter of 7 mm is discharged as a core component, and while being drawn down, α-fluoroacrylic acid 2,2,8°8-tetrafluoropropyl-methyl methacrylate-acrylic is added as a sheath component. A methyl acid copolymer (copolymer composition = 87:10:8% by weight), refractive index 1.41, melt viscosity 8 x 10' poise (210°C)) was melt-coated as a sheath component, and a core with a diameter of 1 cm was formed. The strands have a sheath structure. The thickness of the pod was 10 μm.

When the light guide losses of this optical transmission Iam were measured at 25° C. and 90° C., they were 220 dB/h and 220 dB/lla, respectively, at a wavelength of 65 Q nm.

An olefin-based thermoplastic elastomer heated to 200°C (Sand Breno, 201-64., Monsand Co., Ltd.)
m1) with an outer diameter of 2.0 mm at a speed of 50 m/min using an extruder.
An optical transmission cable with excellent flexibility was obtained by coating the cable so as to have a thickness of 2. After heating this cable at 120° C. for 10 days, the light guide loss was measured to be 280 dB/lII, indicating excellent heat resistance.

Examples 2 to 3 Optical transmission fiber wires were obtained by the same operations as in Example 1, and then coated with thermoplastic elastomer to obtain optical transmission cables with excellent flexibility. All exhibited excellent heat resistance (Table 1).

Comparative Examples 1 and 2 For comparison, optical transmission cables were obtained in the same manner as in Example 1 using various optical transmission fiber wires and thermoplastic resins having different core components.

After heat treatment, all exhibited transmission loss of 700 to 1000 dB/Km or more, and were inferior in heat resistance (Table 2).

Repeated bending test An optical transmission cable was wrapped around a cylinder with a diameter of 10M, and
After repeating the bending process 60,000 times, the appearance of the optical transmission cable was observed.

Claims (3)

[Claims] (1) An optical transmission cable made by coating a thermoplastic elastomer on a strand of optical transmission fiber whose core component is methacrylate resin. (2) The optical transmission cable according to claim 1, wherein the thermoplastic elastomer is an olefin thermoplastic elastomer or an ester thermoplastic elastomer. (3) Methacrylic acid ester 8-8 whose core component has an alicyclic hydrocarbon group consisting of 8 to 20 carbon atoms in the ester moiety
The optical transmission cable according to claim 1 or 2, which is a polymer mainly composed of methyl methacrylate containing 40% by weight.