JPS59136704A - Optical transmission fiber - Google Patents

Abstract

PURPOSE:To improve heat stability, workability, adhesion between a core and a sheath, etc. by using a polymer composed essentially of a specified methacrylate for a core component, and a thermoplastic fluororubber for a sheath component. CONSTITUTION:A polymer composed essentially of methacrylate represented by the formula shown in a figure (R is 1-6C alkyl or 8-20 alicyclic hydrocarbon) is used for a core component and a thermoplastic fluororubber is used for a sheath component. This rubber is composed of a fluororubber phase and a fluororesin phase as follows: As the rubber phase, 10-95pts.wt. polymer having 30- 120 thousand mol.wt. selected from a polymer made from vinylidene fluoride (VDF)/hexafluoropropene or pentafluoropropene/tetrafluoroethylene (TFE) (45-90: 5-50:0-35 molar ratio) and a polymer made from perfluoroalkyl vinyl ether/ TFE/VDF (15-75:0-85:0-85 molar ratio), and as the fluororesin, 5- 95pts.wt. polymer having 10-400 thousand mol.wt. selected from a polymer made from VDF/TFE (0-100:0-100 molar ratio) and a polymer made from ethylene/TFE (40-60:60-40 molar ratio).

Description

[Detailed description of the invention] The present invention relates to a light transmission fiber having a core-sheath structure.

Optical transmission fibers have traditionally been manufactured using glass-based materials, and are widely used as optical signal transmission media for measurement control between and within devices, data transmission, medical use, decoration, and image transmission. . However, optical transmission fibers based on glass-based materials have the disadvantage of poor flexibility unless the fibers are made with a thin inner diameter, are easily broken, have a high specific gravity, and are expensive, including connectors. For these reasons, various attempts have been recently made to make them from plastic.

The main characteristics of using plastic are that it is lightweight, and even fibers with a thick inner diameter are strong and flexible.Therefore, high apertures and large diameters are possible, and it is easy to combine with light receiving and emitting elements. It has excellent operability. The general method for manufacturing such optical transmission fibers using plastic is to use a plastic with a high refractive index and good light transmission as the core component, and a transparent plastic with a lower refractive index than this. The fiber has a core-sheath structure as a sheath component. This method transmits light by reflecting it at the core-sheath interface, and the larger the difference in refractive index between the plastics that make up the core and sheath, the better the light transmission properties.

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

When manufacturing optical transmission fibers, it is basically important to increase the difference in refractive index between the core and sheath, but it is also important to increase the adhesion state at the interface between the core and sheath, as well as the possibility of dust, bubbles, or polymers. The influence of contamination with foreign matter and the physical and mechanical properties of the polymer forming the optical transmission fiber are also important factors.

From this point of view, it has been proposed in Japanese Patent Publication No. 48-8978. A combination of polystyrene resin and polymethyl methacrylate resin, or.

Light transmitting fibers made of a combination of polymethyl methacrylate resin and certain fluorine-containing polymethacrylate resins are noteworthy. However, polyethylene has the disadvantage that the transmitted light has a yellowish tinge, its optical transmission properties are particularly poor in the short wavelength region, and it is easily degraded by light, and the flexibility of the resin, which is poor in flexibility, is further reduced. However, there is also the problem that the adhesion between the pod and the core material is not good.

In addition, certain fluorine-containing polymethacrylate resins, as disclosed in the same publication, have the ability to provide mechanical strength and are especially adaptable to the melt composite spinning method, which is one of the important manufacturing methods for optical transmission fibers. It has the disadvantage of being low. In addition, fluorine-containing alcohols, which are the raw material for these polymers, require advanced technology to synthesize and purify, and are expensive and economically disadvantageous, or have a high refractive index, making it difficult for optical transmission. In addition, these polymers have insufficient heat resistance above 220'O, and have poor flexibility, which impairs flexibility.

As a method to improve these drawbacks, optical transmission fibers using a copolymer of vinylidene fluoride and hexafluoropropylene as a sheath component (Japanese Patent Publication No. 1989-8978) and vinylidene fluoride having a specific copolymer composition have been developed. Optical transmission fibers whose sheath component is a resin which is a copolymer of tetrafluoroethylene (Japanese Patent Publication No. 58-21660, JP-A No. 52-154645, and JP-A No. 54-80)
No. 758) has been proposed. However, the copolymer of vinylidene fluoride and hexafluoropropylene is sticky, has insufficient adhesion to the core component methacrylic resin, lacks stability in interfacial reflectance, and It has drawbacks such as being easily decomposed and difficult to melt and mold, and has extremely little practical value.

In addition, the resin, which is a copolymer consisting of vinyl fluoride, redene, and tetrafluoroethylene, has mechanical toughness such as a low refractive index, bending resistance, and abrasion resistance, but is somewhat crystalline in this composition. However, due to heat treatment, crystallization progresses, resulting in insufficient transparency and low F light transmission, and insufficient adhesion at the interface between the core and sheath components, resulting in large light reflection losses. There are still some points that require improvement. In addition, vinylidene fluoride has insufficient thermal stability, and copolymers containing 60 to 80% vinylidene fluoride have a narrow processing temperature range when coating the core component using the melt composite spinning method. However, there are still many points that need to be improved industrially.Methacrylic acid esters, which are 0° core components, generally have low impact resistance and absorb external impact energy), and it is hoped that a transparent coating material with good adhesion will emerge. was.

In view of the current situation, the present inventors have developed a product with excellent thermal stability,
As a result of extensive research into sheath components that have good processability, flexibility, transparency, and excellent adhesion between the core component and the sheath component, the present invention was arrived at.

The present invention always relates to the general formula (in the formula, an alkyl group having 1 to 8 carbon atoms or an alkyl group having 8 carbon atoms)
- Represents 20 alicyclic hydrocarbon groups. The present invention provides an optical transmission fiber characterized in that the core component is a polymer mainly composed of methacrylic acid ester represented by the formula (2), and the sheath component is thermoplastic fluororubber.

The features of the present invention can be summarized in the following points.

l) As the sheath component, thermoplastic fluororubber is used which has the processability of a thermally conductive resin during melt processing and has the properties of fluororubber in its normal state.

2) Melt composite spinning of the sheath component and core component is possible, and a transparent sheath component can be stably formed.

3) The sheath component has a small refractive index and good adhesion with the core component, and has excellent bending strength and impact strength, so it has excellent light transmission properties.

4) When a methacrylic acid ester having an alicyclic hydrocarbon group having 8 to 20 carbon atoms is used as a core component, heat resistance is significantly improved.

The polymer mainly composed of a methacrylic ester having an alkyl group having 1 to 6 carbon atoms represented by the general formula used as the core component in the present invention contains at least 70% or more of repeating units of the methacrylic ester. A single or copolymer of methacrylic esters containing methacrylic esters, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate,
Homopolymers such as cyclohexyl methacrylate or copolymers thereof, and copolymers thereof with 80% or more of methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, etc. are useful. Among these, polymethyl methacrylate and methyl methacrylate are particularly
% or more of the copolymer is highly pure and extremely transparent,
It is also a preferred core component because it is easily available.

In addition, the methacrylic acid ester having an alicyclic hydrocarbon group having 8 to 20 carbon atoms represented by the general formula A) is a methacrylic acid ester or more preferably an acid chloride thereof, which is represented by the formula ROH
It is produced by esterification with an alicyclic hydrocarbon/monol.

Examples of alicyclic 8-hydrocarbon 11 monools include l-ada7tanol, 2-adamantyl, 8-methyl-1-adamantanol, 3,5-dimethyl-1-adamantanol, and 3-ethyladamantanol. , 3-methyl-5-
Ethyl-1-ada7tanol, 8,5.8-1 ethyl-1-ada7tanol and 8,5-dimethyl-8
-ethyl 1-adantano J, octahydro-
4,7-mentunoinden-5-ol, octahydro-4,7-mentunoinden-1-ylmethanol, p
-menthanol 8, p-menthanol-2,8-hydroxy-2゜6.6-drimethyl-bidiclo(8,1,1
) Heptane, 8,7,7-drimethyl-4-hydroxy-bicycloc411'tO) Hebutane, borneol, isoborneol, 2-methylcamphanol, ethyl alcohol, L-menthanol, 2,2.5-
Examples include alicyclic hydrocarbon monools such as 1-limethyl dichlorohexano-1, and corresponding polymers or copolymers of methacrylic acid esters. The reason why it is limited to alicyclic hydrocarbon groups is that aromatic hydrocarbon groups cause large light guide loss in optical transmission fibers, which limits their use as optical signal transmission media.

Among the alicyclic hydrocarbon groups having 8 or more carbon atoms, alicyclic hydrocarbon groups having 10 to 18 carbon atoms are particularly preferred, as they have a particularly high contribution rate to improving heat resistance.

Among these methacrylic acid esters, particularly preferred 1ζ are 1-adamantyl methacrylate, 2-adamantyl methacrylate, 8,5-dimethyl-1-adamantyl methacrylate, bornyl methacrylate, isobornyl methacrylate, and 1ζ methacrylate. p-menthane, methacrylic acid 2
Examples include polymers or copolymers of methyl camphane, fentyl methacrylate, -L-menthyl methacrylate, and 2,2,5-trimethylcyclohexane methacrylate.

Since the polymer made of the methacrylic acid ester exhibits a high refractive index, it has particularly favorable properties as a light transmission fiber.

The component copolymerized with these methacrylic esters is selected from alkyl acrylates or alkyl methacrylates having an alkyl group having 1 to 6 carbon atoms,
For example, methyl, ethyl, n-propyl, lobethyl,
Alkyl acrylates or alkyl methacrylates having an alkyl group such as cyclohexyl can be effectively used.

The sheath component, which is the most important element constituting the present invention, is a transparent thermoplastic fluororubber that has the processability of a thermoplastic resin during melt processing and has the characteristics of a fluororubber in its normal state.

The thermoplastic fluororubber has a soft segment made of a fluororubber phase and a hard segment made of a fluororesin phase in its molecules, and has rubber elasticity due to physical crosslinking in the fluororesin phase at room temperature. At high temperatures, it behaves similar to thermoplastics.

゛The fluororubber phase forming the soft segment is vinylidene fluoride/hexafluoropropylene or pentafluoropropylene/tetrafluoroethylene (
molar ratio 45-90:5-50:0-35) porin- and perfluoro(alkyl vinyl ether)/tetrafluoroethylene/vinylidene fluoride (molar ratio 15
~75:0~85:O~85) As the fluororesin phase forming the hard segment, vinylidene fluoride/ Tetrafluoroethylene (Mo1L4t, 0-100:O-100) Poly 7
- and ethylene/tetrafluoroethylene (molar ratio 4
Fluororesin 5-90 with a molecular weight of 10,000 to 400,000 selected from poly7-0-60:60-40)
Examples include thermal OJ plastic fluororubber in which parts are bonded together.

These thermoplastic fluororubbers can be blended with conventional fluororubbers, and the processing temperature can be changed.

These thermoplastic fluororubbers are
It can also be blended with rubber, making it a useful means to expand processing temperatures.

The thermoplastic fluororubber is, for example,
No. 786, JP-A-58-86787 and JP-A-58
It is possible to manufacture it by the method described in publications such as No.-86788. In addition, the pond can be manufactured by the method IC of kneading fluororubber and fluororesin. For example, base rubber selected from vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, vinylitine fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, etc. : 10 to 55 parts and a fluororesin 7 selected from vinylidene fluoride-tetrafluoroethylene copolymer, ethylene-tetrafluoroethylene comonomer, etc.
90 to 45 parts at a temperature of 10 to 50°C above the melting point of the fluororesin.
It can be produced by kneading it with a Bamba'J-E mixer or the like at high temperature and pelletizing it.

Preferred examples of these thermoplastic fluororubbers include Guyer Thermoplastic (manufactured by Daikin Industries, Ltd.).

In the case of the core component polymer, these manufacturing methods for the sheath component polymer have no effect on optical transmission properties, so
In particular, the sheath component polymer may be manufactured with care taken to avoid contamination with foreign matter such as dust.

Conventional optical transmission fibers made of plastic have generally been produced by synthesizing a core component using a suspension polymerization method and supplying this to fiber manufacturing equipment. In this method, since a large amount of water is used, foreign substances contained therein are likely to be mixed into the polymer, and there is also a possibility that foreign substances may be mixed in during the dehydration step.

Furthermore, the process of turning the produced polymer into fibers requires a step of pelletizing it for melt spinning, and since the polymer manufacturing equipment and the fiber manufacturing process are located separately, foreign matter can be mixed in. It has disadvantages such as being easily oxidized by air and causing discoloration because it is placed in an environment where it is oxidized by air.

Therefore, a desirable method for manufacturing the optical transmission fiber of the present invention is to carry out the manufacturing step of the core component polymer and the manufacturing step of the optical transmission fiber in a continuous process, and to increase the A two-step production method is preferred: a continuous bulk polymerization step at a temperature of F, followed by a continuous separation step of volatiles mainly consisting of residual unreacted monomers. A desirable manufacturing method is one in which the core component is bulk polymerized, and then both the core component and the component are formed from the obtained polymer by a melt composite spinning method using a double extrusion method.

In the bulk polymerization method, as a radical polymerization initiator, for example, 2,2'-azo-bis(isobutyronitrile), l,
1'-azobis(cyclohexanecarbonitrile), 2
．． 2'-Azobis (2°4-dimethylvurronitrile)
, azo compounds such as azobisisobutanol diacetate, and di-tert-butyl peroxide, dicumyl peroxide, methyl ethyl peroxide, di-tert-butyl perphthalate, di-tert-butyl peroxide,
Examples include organic peroxides such as L-butyl peracetate and di-tert-amyl peroxide.

Further, in order to control the molecular weight, tert-butyl, lobetyl, n-octyl, rhododecyl mercaptan, etc. are added as a chain transfer agent to the polymerization system in an amount of about 1 mol % or more based on the monomer mono 7-.

As described above, the present invention provides an optical transmission fiber having a core-sheath structure, in which the core component has the general formula % (wherein R represents an alicyclic hydrocarbon group having 8 to 20 carbon atoms). When using a polymer whose main component is methacrylic acid ester shown above, and using a thermoplastic fluorine comb as the sheath component, the heat resistance can greatly expand the applicable temperature range of conventional plastic optical transmission fibers. It provides an excellent optical transmission fiber, and its industrial value is extremely high. Since the normal temperature can be 110'C or higher, it can be applied to, for example, automobiles, ships, aircraft, or robots. Also,
The scope of application will also be expanded by relaxing temperature conditions for on-premises and in-building communications.

The present invention will be explained in more detail with reference to uninvented embodiments, but the present invention is not limited thereto.

The light guide loss in the examples was measured using a diffraction grating spectrometer with a halogen tungsten lamp as the light source at 650 nm.
The output intensities of the measured optical transmission fiber and the reference optical transmission fiber at a wavelength of m are read using a silicon photodiode, and from the following formula t, the light guide loss α for the fiber length L (&g) can be calculated from the intensities II and I2. I asked for it.

This formula shows that the smaller the α value, the better the optical transmission performance.

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

Example 1 Polymer ([η], 25
°C, measured in chloroform, 0.70) as the core component,
Using Daiel Thermoplastic T-580 (manufactured by Daikin Industries, Ltd., thermoplastic fluororubber) as a sheath component, melt composite spinning was carried out at a spindle temperature of 260"C and a winding speed of 50sy/mi to produce fibers with a diameter of 1 fl. The blending ratio of the discharged material was set at 90:10 (weight ratio).

Daiel Thermoplastic 1'-580 has a melting point of approximately 22
0°C, specific gravity (d) 1.89. Hardness 5' (JISA) 67, Jll (25C+1.859) (
7) It is thermoplastic fluororubber.

When the light guide loss of this optical transmission fiber was measured, it was found to be 650n.
It was 840 dB/b at m(7) wavelength. Furthermore, this fiber is bent at room temperature with a bending radius of 5 mm and a bending angle of 90 degrees.
1000 bends ζ 1 time/sec) L/Tane, when we observed the peeling state of the core-sheath interface, we found no peeling at all, and the light guide loss retention rate was 100% and no low F was observed. .

Example 2 Butyl acrylate 2096 produced by continuous bulk polymerization method
A polymer mainly composed of fentyl methallylate containing (
[η), 25'C, measured in chloroform, 0.90) as the core component, Daiel Samo Plastic T-510 (manufactured by Daikin Industries, Ltd., thermoplastic fluororubber) as the sheath component, and the base temperature was 260 °C. Melt composite spinning was performed at a winding speed of 93 m/mi to obtain fibers with a diameter of 0.8H.

The blending ratio of the discharged material was set at 85:15 (weight ratio).

The light guide loss of this optical transmission fiber was measured to be -650n.
It was 860 dB/btt at a wavelength of m. Furthermore, when this fiber was heat treated at 180°C for 7 hours and the light guide loss was measured, it showed excellent heat resistance of 8'1 OdB/btr.

Example 3 1.5% methyl acrylate produced by continuous bulk polymerization method
Polymers mainly composed of polymethyl methacrylate ([
η]25℃, chloroform, 0.75) as the core component,
Daiel Thermoplastic T-680 (manufactured by Daikin Industries, Ltd., thermoplastic fluororubber) was used as a sheath component, and melt composite spinning was carried out at a spindle temperature of 225''C and a winding speed of 50 m/mi, and then at 150゛C. The fibers were drawn 1.5 times to obtain a final fiber with a diameter of 0.8 fl.The blending ratio of the extrudate was set at 90:10 (weight ratio).

Daiel Thermoplastic T-680 has a melting point of approximately 160
'c, specific gravity (d) 1.89. It is a thermoplastic fluororubber with a hardness of 5 jJIs A) 61 and a refractive index (25° C.) of 1.87.

When the light guide loss of this optical transmission fiber was measured, it was found that (i 5
It was 800 dt3/kM at a wavelength of Q nm. The fibers also had extremely good bending strength.

Example 4 A fluororubber phase (vinylidene fluoride/hexafluoropropylene = 78/22 molar ratio) was used as a thermoplastic rubber.
55 parts) and polyvinylidene fluoride as a fluororesin phase (45 parts) for the core component of Example 1 using a thermoplastic fluororubber as the sheath component, at a mouth temperature of 280°C and a winding speed of 5 Q 111 / rnl n Melt composite spinning was performed to obtain fibers with a diameter of I NM. The blending ratio of the discharged material was set to 15:95 (weight ratio).

When the light guide loss of this optical transmission fiber was measured, it was found to be 650n.
mcy) wavelength is 870 dB/kar.

Example 5 Polymer mainly composed of bornyl methacrylate containing 10% butyl acrylate produced by continuous bulk polymerization method (
[η], 25°C, measured in chloroform, 0.95) as the core component, Daiel Thermoplastic T-580 (
Melt composite spinning was carried out under the same conditions as in Example 2 using thermoplastic fluororubber (manufactured by Daikin Industries, Ltd.) as the sheath component to obtain fibers with a diameter of 1.0 mm.

When the light guide loss of this optical transmission fiber was measured, it was found to be 650n.
mc+) wavelength was 400 dB/km.

Furthermore, when this fiber was heat-treated at 40'C for 24 hours to 9 hours, the shear light guide loss was measured, and it was found that 400 d
It showed excellent heat resistance with B/b. .

Procedural amendment (voluntary) August 1'1, 1980 Director of the Patent Office Kazuo Wakasugi 1, Indication of the case 1988 Patent Application No. 11007-2, Title of invention Optical transmission fiber 3, Make amendments Relationship with the Patent Case Patent Applicant Address 5-15 Kitahama, Higashi-ku, Osaka Name (2
09) Sumitomo Chemical Co., Ltd. Representative Hijikata
Take 4, Agent Address: 6, Sumitomo Chemical Co., Ltd., 5-15 Kitahama, Higashi-ku, Osaka, Japan Contents of the amendment (1) ``Proposed on page 4 of the specification, line 7 from the bottom.''

``Polystyrene'' is referred to as ``Proposed Polystyrene.''

(2) ``1-methacrylic acid ester'' on the 4th to 5th lines from the top of page 9 of the specification is referred to as ``methyl methacrylate.''

(3) In the third line from the bottom on page 17 of the specification, after "in the formula, R is", "an alkyl group having 1 to 6 carbon atoms or" is added.

that's all 21

Claims (2)

[Claims] (1) An optical transmission fiber characterized in that a core component is a polymer mainly composed of a methacrylic acid ester represented by the general formula %, and a sheath component is a thermoplastic fluororubber. (2) Thermal 0Jfvi fluororubber is a fluororubber phase containing vinylidene fluoride/hexafluoropropene or pentafluoropropene/tetrafluoroethylene (mole ratio 45-90:5 50:0-35) poly7-
and fluororubber 10 with a molecular weight of 80.000-1, 200.000 selected from perfluoro(alkyl vinyl ether)/tetrafluoroethylene/vinylidene fluoride (molar ratio 15-76:θ-85:0-85) polyline. ~95 parts and vinylidene fluoride/tetrafluoroethylene as the fluororesin phase (molar ratio θ ~100
:0-100) and polymers of ethylene/tetrafluoroethylene (molar ratio 40-60:60-40) with a molecular weight of 10.000-400,000.
Thermoplastic fluorine resin combined with 5 to 90 parts of fluororesin
The optical transmission fiber according to claim 1, which is a fiber.