JPS61252507A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To provide a plastic optical fiber which is free from structural defects and has improved heat resistance and the resistance to repetive flexural operations and to make possible the low optical transmission loss thereof by using a core material layer, sleeve material layer and protective layer as the basic constituting units and establishing the specific relation among the respective melt flows of the three layers. CONSTITUTION:The core material layer consisting of a polymer consisting essentially of methyl methacrylate, the sleeve material layer consisting of a polymer having at least one repeating unit expressed by the formulas as the component and the protective layer consisting of polycarbonate are used as the basic constituting units. The melt flow rate (MFR)1 of the polymer of the core material layer, the melt flow rate (MFR)2 of the polymer of the sleeve material layer and the melt flow rate (MFR)3 of the polycarbonate of the protective layer measured respectively under the conditions of 230 deg.C test temp. and 5kg test load are made to attain the values satisfying the relation (MFR)1<=(MFR)2<=(MFR)3<=40g/10min. The coating layer 4 constituted of a jacket material consisting of an org. polymer is coated on the optical fiber core having the three-layered structure to constitute the optical fiber cable having the four-layered structure. The optical fiber which has the excellent heat resistance and the good resistant to the repetitive flexural operation, is free from the structural defects and has the low optical transmission loss is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic optical fiber that can be used as an optical fiber, a cored optical fiber, an optical fiber cord, an optical fiber cable, or the like.

[Conventional technology]

Conventionally, inorganic glass optical fibers have been known as optical fibers for optical transmission, which have excellent optical transmission properties over a wide range of wavelengths, but they have poor processability, are weak against bending stress, and are expensive. Glass optical fibers based on synthetic resin have been developed. Synthetic resin optical fibers have a core-sheath structure, with a core made of a polymer with a high refractive index and good light transmission, and a sheath made of a transparent polymer with a low refractive index. Obtained by manufacturing. The polymer useful as a core component with high light transparency is preferably an amorphous material, and methyl methacrylate or polystyrene is generally used.

Among these, polymethyl methacrylate has excellent transparency, mechanical properties, weather resistance, etc., and is used industrially as a core material for high-performance plastic optical fibers.

However, plasti with a core of polymethyl methacrylate,
The optically transmitting fiber has a glass transition temperature (Tg) of polymethyl methacrylate of 100°C and an environmental condition of use of 100°C.
It cannot be used at all if the temperature exceeds ℃, and this limitation in heat resistance limits the uses of glass optical fibers.

For this reason, for example, in Japanese Patent Application Laid-Open No. 58-18608, three layers of engineering plastics having heat resistance and high strength, such as I liquor, nate, polyamide, and polyacetal, are used to surround the sheath material. It has been proposed to improve the mechanical properties and heat resistance of optical fibers with the above structure, but even if such materials are used, the heat resistance is not sufficient and the optical transmission loss deteriorates at high temperatures. Wake up,
This has significantly delayed its use as a means of optical communication or as a means of optical sensors installed in high-temperature areas such as the engine rooms of automobiles and ships.

Furthermore, if an attempt was made to improve the heat resistance using this glaze material, it would not impair other properties desired for the optical fiber, and for example, problems would arise, such as increased loss due to repeated bending.

In addition, as a manufacturing problem, when forming the three layers of the core, sheath, and protective layer integrally by melt composite spinning, if the fluidity of the material constituting each layer is not optimized, the fiber to be formed will This resulted in problems such as structural defects such as thread spots, adversely affecting optical transmission characteristics, and interfering with fiber connections.

[Problems to be solved by the invention]

The present invention aims to solve the heat resistance problems, mechanical problems, housing problems, and manufacturing problems associated with the conventional plastic optical fibers described above. By optimizing the combination, the present invention provides a plastic optical fiber that is free from structural defects, has excellent heat resistance, has excellent resistance to repeated bending operations, and has low optical transmission loss.

[Failure to solve the problem]

That is, the plastic optical fiber of the present invention, which was discovered as a means to solve the above problems, has a core material layer made of a polymer containing methyl methacrylate as a main component, and a core material layer made of a polymer having the following general formula [I].
1 whose component is at least one of the repeating units shown in
(MFRI , , Melt 70-ray of sheath material layer polymer) (Melt 70-ray of MFRI2 and protective layer polycarbonate) [MFR] 1 is [MF
R〕1≦(MFR132≦[MFR]1≦40 fP/
It is characterized by taking a value that satisfies a 10-minute relationship.

〔Example〕

FIGS. 1 to 3 are cross-sectional views for explaining configuration examples of the plastic optical fiber of the present invention. The example shown in FIG. 1 is an optical fiber core wire having a three-layer structure: a core material layer (core) 1, a sheath material layer (cladding) 2, and a protective layer 303.

Hereinafter, the same elements as in Fig. 1 will be represented by the same symbols. The example in Fig. 2 is composed of a core 1, a cladding 2, a protective layer 3 made of an organic polymer, and a jacket material made of an organic polymer. This is an optical fiber cable having a four-layer structure with a covering layer 404.

In the example shown in FIG. 3, a plurality of optical fiber cores 5 having a three-layer structure consisting of a core 1, a core 1, a fiber 2, and a protective layer 3 made of an organic polymer are connected to a coating layer 4 made of a jacket material made of an organic polymer. It is a multi-core optical fiber cord coated with

The configuration of the plastic optical fiber of the present invention is not limited to the examples shown in FIGS. 1 to 4, and at least the basic structural unit is
Core and core used in the present invention.

It is sufficient if it consists of a code. Furthermore, a fiber configuration may be adopted in which, for example, a tension member made of steel or FRP or a metal coating is incorporated into the optical fiber, or a configuration may be adopted in which the coating is further layered in a desired number of layers.

In the present invention, the melt flow sheet) [MFR].

and (MFR)2 are, for example, Japanese Industrial Standards JIS K7
210-1976, American Materials Testing Standard A8TM D12
38-82, sb at a melt flow rate that can be measured in accordance with the international standard ISO 1133, e.g. JI
When complying with S K 7210-1976, use method A (manual cutting υ method), test temperature 230℃, test load 5k
It is measured in g. In addition, as other test conditions, the length of the die is determined to be s, ooo±0.025mm, and the inner diameter is 2.095±0.005mm.

Is the sample photoresistance 5? In the case of method A, the sample collection time is approximately 30 seconds.

Also, ASTM D 1238-82, ISO11
When measuring in accordance with 33, these test conditions and measurement conditions are also adopted. Furthermore, the equipment and tools used for measurement, as well as the measurement procedure, can be determined within the range specified by each standard.

As the base material for the cores 1, 1', non-grade transparent polymers are suitable, such as homopolymers or copolymers of methyl methacrylate, of which 70 to 1 of the starting monomers are used.
Preferably, 00% by weight is methyl methacrylate and 30 to 0% by weight is a monomer copolymerizable with methyl methacrylate. Examples of monomers that can be copolymerized with methyl methacrylate include vinyl monomers such as methyl acrylate and ethyl acrylate.

Also usable are deuterated polymers in which all or some of the hydrogen atoms of these polymers containing methyl methacrylate as a main component are replaced with deuterium atoms.

The general formula (
In the repeating unit of 1), the number of carbon atoms represented by R is 1 to
Examples of the alkyl group in 5 include methyl group, ethyl group,
n-f propyl group, 1-easy O-propyl group, n-ethyl group,
Examples include l-methyl group, I@C-butyl group, tart-butyl group, and the like. The fluorinated alkyl group having 1 to 5 carbon atoms represented by R is -C(CF,), -CH,CH
, CF2CF2CF, .

-CH2CF, CF2CF2CF2H, -CM2CF2
There are CF2CF2CF, etc. Number of carbon atoms represented by R is 3
Examples of the cycloalkyl group of -6 include a cycloalkyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. One or more of the hydrogen atoms constituting these alkyl groups, fluorinated alkyl groups, and cycloalkyl groups may be substituted with, for example, a halodane atom, a monovalent organic group, or the like.

In the repeating unit of general formula (1), R is preferably an alkyl group having 1 to 3 carbon atoms or a fluorinated alkyl group having 1 to 3 carbon atoms.

Further, the structure of the sheath material layer polymer may be composed of only one type or two or more types of repeating units of the general formula (1), or one of the repeating units of the general formula [I]. In addition to the species or two or more, other repeating units or functional groups may be introduced as described below in the production method, and in this case, one of the repeating units of the general formula CI) Alternatively, it is desirable to contain 10 mol or more of two or more types.

Furthermore, when two or more types of repeating units of the general formula [I] with different R are used, these repeating units can be used in any ratio. For example, a repeating unit in which R is an alkyl group having 1 to 3 carbon atoms and a repeating unit in which R is a fluorinated alkyl group having 1 to 3 carbon atoms may be combined in any blending ratio.

The polymer constituting the sheath material layer includes α-fluoroacrylic acid alkyl ester, α-fluoroacrylic acid fluorinated alkyl ester, and - One or two selected from cycloalkylnysteel fluoroacrylate
One or more kinds of seven monomers and, if necessary, other copolymerizable monomers (such as methacrylic acid, alkyl methacrylates such as methyl methacrylate, etc.) ester, methacrylic acid 2
, 2,3,3.3-hentafluoroprobil and other fluorinated alkyl methacrylates, vinylidene fluoride, and the like. ], and can be obtained by polymerizing according to a conventionally known polymerization method.

(MFR)2 of the sheath material layer polymer is as follows: [MFR]1≦[:MFR]2≦[:MFR],≦40
p710 minutes. (MFRI2 is [MFR
If the value is less than 1, the flow of the polymer in the nozzle is not likely to be disturbed, and optical transmission loss due to core-sheath interfacial asymmetry, that is, structural asymmetry, increases, which is undesirable.

If the MFRI2 exceeds 40/10 minutes, it is not preferable because the coating of the sheath becomes large, the degree of polymerization of the sheath material is too low, and the bending characteristics of the optical fiber deteriorate.

A more preferable range of [MFR]2 is: [MFR]1≦[MFR]223307710 minutes, and an even more preferable range is: 5p710 minutes≦(MFR,l,≦20p710 minutes).

Suitable polycarbonates constituting the protective layer 3 include:
General formula (-0-R, -0-C+ +1
”, where R1 is an alicyclic polycarbonate represented by O, aromatic polycargonate represented by O, and 4,4'-dioxydiphenyl ether, ethylene glycol, p- xylylene glycol, 1
．． Copolymers with dioxy compounds such as 6-hexanediol can also be used, but from the viewpoint of heat resistance, those with a heat distortion temperature of 120° C. or higher are preferred.

Here, heat distortion temperature is defined by the American Standard for Materials Testing (STMD).
-648, the measured value at a load of 4.6 k5F/-.

In particular, in the plastic optical fiber of the present invention, the protective layer polycarbonate (melt flow layer) [MFR
], must be equal to or larger than (MFR)2. That is, [:MFR)2> [:MFR3g
If this is the case, the flow of the polymer in the nozzle will be disturbed, which will have a significant adverse effect on yarn unevenness, which is not preferable.

Furthermore, considering the fluidity of the protective layer polycarnate in the molten state, the intrinsic viscosity (in methylene chloride, 20°C
) is preferably 0.6 dl/y- or less. The intrinsic viscosity is preferably in the range of 0.3 to 0.5 dl/P, and if it is less than 0.3 dj/p, it becomes extremely difficult to control yarn diameter unevenness.

The thickness of the protective layer is not particularly limited, but it is preferably in the range of 10 to 250 μm, taking into consideration the thermal shrinkage characteristics of the optical fiber, distortion suppression, and optical transmission loss when subjected to thermal history. Furthermore, 10 to 100 μm, even more still 30 to 100 μm
It is preferable to set it to 50 micrometers.

Furthermore, in order to increase the stability of the fiber, for example, an ultraviolet absorber or an ultraviolet absorber is added to the preservation layer to prevent deterioration caused by ultraviolet light.
Carden plastic to improve heat resistance and mechanical strength,
In addition, fillers such as glass fibers, antioxidants, etc. can be contained in order to improve flame retardancy.

In the plastic optical fiber of the present invention, the organic polymer constituting the coating layer 4 is intended to improve the properties of the plastic optical fiber in addition to the properties that the present invention aims to improve. can be arbitrarily selected as desired.

For example, in order to improve the heat resistance, heat shrinkage resistance, and mechanical properties of the optical fiber, the coating layer 4 can be made of an organic polymer having a heat distortion temperature of 100° C. or higher. Heat distortion temperature 1
Examples of organic polymers having a temperature of 00°C or higher include polyester, ? Lyamide, poly4-methylpentene-1, vinylidene litz, polyacetal, polysulfone, ? So-called engineering plastics such as poly(ethylene terephthalate, polypropylene, polyoxymethylene, polybutene, polytetramethylene ethylene terephthalate), ABS, polyphenylene oxide, and polycarbonate can be used.

Further, for example, water-crosslinked polyolefins can be selectively used for the purpose of improving the heat resistance, heat shrinkage characteristics, light transmission characteristics, etc. of the optical fiber.

In the present invention, melt composite spinning is used as a method for shaping the glass optical fiber.

For example, when producing an optical fiber having a three-layer structure by melt composite spinning, a composite spinning machine consisting of a core layer component melt extrusion machine, a sheath material layer component melt extrusion machine, and a protective layer component melt extrusion machine is used. The core component is melted in a melt extrusion manner and fed to the metering spinning head with a metering pump, and the composition and protective layer components are each fed to the spinning head in a similar manner. It is shaped into a three-layer structure using a spinneret in a spinning head and discharged, and after being cooled and solidified, it is wound up and optionally subjected to stretching or annealing treatment. In Figure 2, from (4) to the core material layer components, (
The sheath material layer component is supplied from B), the protective layer component is supplied from Q, and is discharged from (B).In addition, when shaping a core-sheath two-layer fiber, the shape of the spinneret must be adjusted. The rest is shaped in the same way as in the case of a three-layer structure.In addition, in the case of a structure with four or more layers as shown in Figure 3, for example, up to the third layer can be shaped by melt composite spinning. , a method is adopted in which the fourth layer is shaped by a coating process such as extrusion or coating.

In the present invention, when shaping the core-sheath protective layer, which is a basic structural unit, by melt composite spinning, the spinning temperature is set at 215 to
The temperature is preferably 245°C. This is because if the spinning temperature is less than 215° C., the melt viscosity is too high and the yarn diameter becomes extremely uneven. This is because if the temperature exceeds 245° C., the sheath material will thermally decompose within the nozzle, resulting in poor loss due to heat banding and foaming. A more preferable spinning temperature is 220-2
It is in the range of 30°C.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 100 parts of methyl dimethacrylate was produced by continuous bulk polymerization using a volatile matter separator consisting of a reaction tank equipped with a Spiral Lime 7 type stirrer and a twin-screw one-vent type extruder.
A monomer mixture consisting of 0.40 parts of t-butyl mercaptan and 0.0017 parts of di-t-butylno-9-oxide was reacted at a polymerization temperature of 155°C and an average residence time of 4.0 hours, and then the temperature of the pent extruder was adjusted to The pent part was set at 240° C. and the extrusion part was set at 230 tl, and the degree of vacuum at the vent part was set to 4 imHg, and the volatile part was separated to obtain a core component polymer.

3-(3,5-t-butyl-4-hydroxyphenyl)propione) (trade name: IRGANOX1076) was added to 100 parts of this core component polymer (PMMA) in acetone and purified by filtration with a 0.1μ Teflon filter.
and dilaurylthiodiglopionate at 0.2 each.
After kneading 0.1 part and 0.1 part, the mixture was supplied to a core-sheath two-component composite spinning head at 225°C through a gadging section maintained at 225°C.

On the other hand, a copolymer obtained from a heptamer mixture obtained by mixing methyl α-fluoroacrylate and 2,2,3,3,3-pentafluoropropyl α-fluoroacrylate in equimolar amounts was used as a sheath component polymer. It was supplied to a core-sheath two-component composite spinning head.

In addition, as a component polymer for the protection layer, commercially available Telikanate (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name H-4000) was melted and supplied to a core-sheath protective layer three-component composite spinning head.

The molten polymer fed at the same time was
It is discharged at 25℃, after cooling and solidifying, it is rolled up and the core material layer diameter is 9.
A plastic optical fiber having a thickness of 20 μm, a sheath member thickness of 4 μm, and a protective layer thickness of 36 μm was obtained.

The heat resistance, optical transmission loss, cyclic bendability, and thread unevenness of the shaped fiber were evaluated using the following evaluation methods, and the results are shown in Table 1.

[Fiber characteristics evaluation method]

(1) Optical transmission loss Measured according to the method disclosed in Japanese Patent Application Laid-Open No. 58-7602. The measurement light wavelength was 650 nm, and the numerical aperture of the fiber incident light was 0.6. The unit is dB/-0 (2) Repeat bendable fiber is placed on a mandrel with a diameter 5 times the fiber diameter.
It was bent repeatedly, and the number of bends when the light intensity retention rate was 50 degrees was read.

(3) Increase in optical transmission loss (dB/la) after heating the heat-resistant fiber at 1-15°C for 30oO hours.

(4) Thread unevenness Thread unevenness was measured on a length of 500 wt using a Rede wire diameter measuring machine.

Examples 2-4. Comparative Examples 1 to 3 The same plasti as in Example 1, except that the spinning temperature or the composition of the sheath components were changed to those shown in Table 1.

An optical fiber was obtained. The properties of these fibers were evaluated using the same method as in Example 1, and the results are shown in Table 1.

Note) Polymer A: A copolymer of methyl α-fluoroacrylate and 2,2,3,3゜3-e-entafluoroprovir α-fluoroacrylate at a molar ratio of 250.

Polymer B: Homopolymer of methyl α-fluoroacrylate.

PC is polycarbonate), PE is polyethylene, 3FM
represents polyfluoroethyl methacrylate (2,2,2-).

Examples 9-11. Comparative Examples 12-13 The spinning temperature was 230°C, 240°C, and 210°C.

The same optical fiber as in Example 1 was obtained except that the temperature was 250°C. Similarly, thread spotting (loss) was evaluated and the results are shown in Table 2.

Table 2 Example 12 The optical fiber formed up to the protective layer according to Example 1 was further coated with commercially available water-crosslinked polyethylene (trade name Linkron MP-
70ON, density 0.945 P/a (manufactured by Mitsubishi Yuka ■)
A plastic optical fiber cable with a diameter of 2.2 m was obtained.

The cable thus obtained was further excellent in heat resistance, heat shrinkage characteristics, light transmission characteristics, and the like.

〔Effect of the invention〕

The plastic optical fiber manufactured according to the present invention can be used for all kinds of purposes as an optical transmission fiber, and has excellent heat resistance so that it can be used even under harsh conditions such as in the engine room of automobiles and ships. has
Furthermore, it has good resistance to repeated bending operations, has no structural defects, and has low optical transmission loss.

[Brief explanation of drawings]

FIGS. 1 to 3 are cross-sectional views for explaining configuration examples of the glass optical fiber of the present invention. In more detail, Fig. 1 shows an example of the configuration of an optical fiber core, Fig. 2 shows an example of the configuration of an optical 7-iper cable, and Figure 3 shows an example of the configuration of a multi-core optical fiber cord. It is a front view. Figure 4 is a sectional view of a spinneret for shaping the plastic optical fiber of the present invention. 1... Core material layer (core), 2... Sheath material layer (cladding)
3... Protective layer, 4... Covering layer.

Claims (3)

[Claims] (1) Consisting of a core material layer made of a polymer whose main component is methyl methacrylate, a sheath material layer made of a polymer whose component is at least one of the repeating units represented by the following general formula [I], and polycarbonate. The melt flow rate of the core layer polymer [M
FR]_1, Melt flow rate of sheath material layer polymer [MF
R]_2 and the melt flow rate [MFR]_3 of the protective layer polycarbonate are [MFR]_1≦[MFR]_2
A plastic optical fiber characterized by having a value satisfying the relationship: ≦[MFR]_3≦40g/10 minutes. [Note] General formula [I] ▲ Numerical formulas, chemical formulas, tables, etc. (represents a cycloalkyl group) (2) The plastic optical fiber according to claim (1), wherein the protective layer has a thickness of 10 to 250 μm. (3) The plastic optical fiber according to claim (1) or (2), wherein the spinning temperature is 215 to 245°C.