JPS60201304A - Light transmittable optical fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention Technical Field The present invention relates to a light transmitting fiber, and more specifically, to a plastic light transmitting fiber having a core-sheath dual structure and having excellent heat resistance. It is.

TECHNICAL BACKGROUND Conventionally, as light transmitting fibers, inorganic glass-based optical fibers having poor light transmitting properties over a wide range of wavelengths have been known. However, glass fibers have poor processability, are susceptible to bending stress, and are also expensive, so light transmitting fibers based on synthetic resins have been developed. Light transmitting fibers made of synthetic resin have a core component that is a polymer with a high refractive index and good original transparency, and a sheath component that is a transparent polymer that has a lower refractive index than the core component polymer. It is obtained by producing a fiber having a core-sheath dual structure. The polymer useful as a core component with high light transparency is preferably an amorphous material, and polymethyl methacrylate or polystyrene is generally used.

Among these, polymethyl methacrylate has excellent not only transparency but also mechanical properties and weather resistance, and is therefore used industrially as a core material for high-performance plastic optical fibers, and is used in short-distance optical communications, optical fibers, etc. Application development is progressing in the following fields. However, polymethyl methacrylate has a heat deformation temperature of around 100°C on the negative side, and does not have sufficient heat resistance.Therefore, there are many fields in which its application is restricted, and therefore there is a demand for improved heat resistance. Highly desired.

To date, many studies have been conducted to improve the heat resistance of methacrylic resins, and several reports and proposals have been made.One of them is the copolymerization of α-methylstyrene with methyl methacrylate as a heat-resistant component. There is a method, but α-
The polymerization rate of methylstyrene is extremely slow, and the mechanical strength of the resulting polymer is low (also, the molded product becomes noticeably discolored, although heat resistance has been improved to some extent, it has major drawbacks. Although a copolymer of maleic anhydride and methyl methacrylate has been reported in J. Polymer Science [J, PolymarSet], Vol. 5, p. 253 (1950), it has not been put to practical use. Furthermore, Japanese Patent Publication No. 45-31953 proposes copolymerizing methyl methacrylate with α-methylstyrene and maleic anhydride, but this method is difficult to control the polymerization reaction because it involves a multicomponent system. The resulting copolymer also has the disadvantage that it is difficult to obtain a uniform composition.

Object of the Invention The object of the present invention is to not only have excellent optical properties, mechanical properties, weather resistance, and moldability comparable to polymethacrylic acid ester resins (but also excellent heat resistance and moldability). An object of the present invention is to provide a light transmitting fiber having excellent light transmitting properties, which is composed of a core component polymer having good properties and productivity, and a sheath component polymer having excellent heat resistance and thermal stability.

Structure of the Invention The light transmitting fiber of the present invention has 67 to 67 methyl methacrylate units.
99% by weight and 1-33mt% of maleic anhydride units, and has an intrinsic viscosity of 0.99% by weight when measured in chloroform at 25°C.
35-2.0 di/p, residual monomer content 1.
0! a core component comprising a methacrylic resin having an amount of 1% or less, and a sheath component covering the core component and comprising a polymer having a refractive index 1% or more lower than the refractive index of the core component copolymer. It is characterized by ε comprising.

3. Detailed Description of the Invention In the light transmitting fiber of the present invention, the core component methacrylic resin is characterized in that it essentially consists of two units: a methyl methacrylate unit and a maleic anhydride unit, Without introducing a third component, it has a higher heat deformation temperature than methacrylic resin, has excellent heat decomposition resistance, has better uniformity than multi-component systems, exhibits excellent optical transmission and mechanical properties, and is easy to manufacture. A core component with good properties was obtained.

By using a core component polymer having such excellent properties, it was possible to obtain an excellent light transmitting fiber with balanced performance.

In the light transmitting fiber of the present invention, the core component polymer consists essentially of 67 to 99 weight percent of methyl methacrylate units and 1 to 33 weight percent of maleic anhydride units, and the content of maleic anhydride units in the resin is If it exceeds 33% by weight, not only will productivity drop significantly, but it will also be difficult to maintain the excellent weather resistance, hot water resistance, etc. as a methacrylic resin, and if the content of maleic anhydride units exceeds 1% by weight. If the amount is less than 500, no substantial improvement in heat resistance can be expected.

Further, the core component polymer of the present invention has an intrinsic viscosity value of 0.35 to 2.0 dl/, measured in chloroform at 25°C.
It is desirable that it be in the range of / . Intrinsic viscosity is 0.3
If the intrinsic viscosity is less than 5 dl/l, the mechanical properties will be insufficient for practical use, while if the intrinsic viscosity exceeds 2.0 dlIP, molding will become difficult. A more preferable value of intrinsic viscosity is 0
．． It ranges from 40 to 5 dl/y.

Further, the amount of residual monomer in the core component polymer of the present invention is 1.0
It is desirable that the weight is less than 0.7 weight, preferably less than 0.7 weight. Residual monomer in core component polymer is 1.0 wt%
If the temperature exceeds this value, the heat deformation resistance decreases, and in extreme cases, the foaming phenomenon caused by volatilization during heat processing may impair transmission properties.

Furthermore, since the residual maleic anhydride monomer in the core component polymer greatly affects water resistance, the residual amount should be reduced to 0.
It is desirable that the weight ratio be 3 or less, preferably 0.15 or less.

The core component copolymer used in the present invention consists essentially of the aforementioned methyl methacrylate units and maleic anhydride units, but in addition to these component units, a small amount, preferably 20% by weight or less, of a copolymer is also present. It may also contain a polymeric component. This copolymerization component is composed of one or more monomers having an ethylenic double bond, such as methacrylic acid, acrylic acid, methyl acrylate, ethyl acrylate R, and vinyl acetate, depending on the purpose. It may be something.

In addition, the core component is a mixture of a polymer containing a dominant amount of the above-mentioned copolymer, preferably 80' or more, and a minor amount, preferably 20% by weight or less, of methyl methacrylate of 80 or more by weight. It may be. 1 The core component copolymer of the present invention can be produced by bulk or solution polymerization of a monomer mixture of methyl methacrylate and maleic anhydride.

Examples of the solvent used in producing the core component copolymer of the present invention by solution polymerization include benzene, toluene, xylene, ethylbenzene, acetone, methyl ethyl ketone, and tetrahydrofuran.

The polymerization temperature in bulk polymerization R and solution polymerization is 100-1
80°C is preferred. It is also advantageous to use a radical polymerization initiator. Examples of the radical polymerization initiator used include organic peroxides such as di-tart-butyl peroxide and dicumyl peroxide, and azo compounds such as azobisisobutanol diacetate and 1,1-azobiscyclohexanecarbonitrile. It will be done. These radical polymerization initiators may be used alone or in combination of two or more.

The amount of radical polymerization initiator used is 0 based on the total monomer.
．． 0001 to 10% by weight, preferably 0.0002 to 1
He is in charge of weight. Further, when producing the core component copolymer of the present invention, a chain transfer agent such as mercaptaf can be used for the purpose of controlling the molecular weight. Examples of mercaptans used as chain transfer agents include primary, secondary and tertiary mercaptans with alkyl or substituted alkyl groups, such as n-butylmercaptan, n-octylmercaptan, n-dodecylmercaptan. Kaptahu, tert
- Examples include dodecyl mercaptan. When mercaptan is used, it is used in an amount of 1 mole or less based on the monomer.

The polymerization apparatus used to produce the core component copolymer of the present invention is not particularly limited, and may include various types such as seed type, tower type, pipe type, duct type, etc.
From the viewpoint of maintaining the uniformity of the polymerization reaction within the polymerization reactor, a reactor selected from a complete mixing type reactor, a plug flow type reactor, and a combination thereof is preferable.

When using these polymerization apparatuses, either a batch method or a continuous method can be applied to the polymerization.

The composition ratio of methyl methacrylate and maleic anhydride supplied to the polymerization reactor when producing a copolymer by a batch method or a continuous method has a large influence on the physical properties S and polymerization reactivity of the resulting copolymer. Therefore, it is necessary to appropriately select the polymerization method in consideration of the polymerization method to be employed and the polymerization rate to be achieved. The composition ratio of methyl methacrylate and maleic anhydride when obtaining the copolymer of the present invention is preferably 20 or less in terms of molar ratio of maleic anhydride to methyl methacrylate in the polymerization reactor, whether it is a batch method or a continuous method. 0. It is preferable to maintain the unreacted monomer ratio within a range of O1 to O10. If the molar ratio of maleic anhydride monomer to methyl methacrylate monomer in the reactor exceeds 20, the polymerization rate will drop significantly and only a colored, low molecular weight copolymer will be obtained.

Since the core component copolymer of the present invention produced by the method described above contains volatile components such as unreacted monomers and/or solvents, it is subsequently heated under reduced pressure to remove volatile components. Separate and remove the majority, or dissolve, reprecipitate,
Depending on the drying method, a predetermined amount of residual monomer content is achieved.

Equipment used to remove volatiles includes, for example, pent extruders or other devolatizers as known in the art. The volatilized and separated copolymer is extruded in a molten state through a die or the like, molded into a desired shape, and used.

In the core component copolymer of the present invention, a small amount of other comonomers, a plasticizer, a crosslinking agent, a heat stabilizer 8, a mold release agent, etc. may be added as necessary depending on the product type and quality requirements. You can also do it.

In the light transmitting fiber of the present invention, the core component is.

Covered by a sheath component. The sheath component is formed by a polymer having a refractive index that is at least 11 less than the refractive index of the core component copolymer. This polymer has a glass transition point of 80°C or higher and is preferably substantially transparent. Special Publication No. 56-8322,
Japanese Patent Publication No. 56-8323 and Japanese Patent Publication No. 53-60243
Polymers of fluorinated alcohol esters of methacrylic acid and Japanese Patent Publication No. 53-422, as described in No.
Copolymers of vinylizo fluoride/and tetrafluoroethylene as described in No. 60, polymethyl methacrylate, polysiloxane and ethylene-vinyl acetate copolymers 1
You can choose from combinations etc.

The above-mentioned meth, acrylic acid-7-fluorinated alcohol ester has the following general formula: [However, in the above formula, X represents H, F or CI atom, and n is 1
represents an integer of ~6, m represents an integer of 1 to 10, l represents 1
It represents an integer of ~10, and R, g and town are each an H atom or OH (Ct)Is or CF.

There is a compound represented by [representing a group]. Such methacrylic acid fluoroalkyl ester may be x-polymerized alone, or may be copolymerized with other polymerizable vinyl monomers.

Such vinyl monomers include methyl methacrylate, ethyl methacrylate, propyl methacrylate,
Butyl methacrylate, cyclohexyl methacrylate, glycidyl methacrylate, methacrylic acid, acrylic acid, maleic anhydride, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, be/dyl acrylate, glycidyl methacrylate, glycidyl acrylate, styrene , α-methylstyrene, vinylpytolz
, z, 4-dimethylstyrene, p-chlorostyrene,
2.4-dichlorostyrene, p-methoxystyrene,
Acrylonitrile, methacrylate trile, vinyl acetate,
Examples include methyl vinyl ketone, hydromutipropyl acrylate, hydromutidiethyl acrylate, and the like. Two or more of these monomers may be copolymerized in combination.

Among them, methyl methacrylate is particularly preferred from the standpoint of providing a transparent copolymer.

The sheath component polymer is produced by radical polymerization of polymerization components by a conventional method. As the polymerization catalyst at this time, a usual radical polymerization initiator can be used, and specific examples include di-tert-butyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, tart-butyl verphthalate, and tert-butyl peroxide. Berbenzoate, methylimbutylketone peroxide, lauroylperoxide, cyclohexane peroxide, 2,5-dimethyl-2゜5-di-tart-butylberogysihexane, tert-butylberoctanoate, tert-butylperymptylate) ,te
Organic peroxides such as rt-butylperoxyingropyl carbonate, methyl 2,2'-azobisisobutyrate, 1,1'-azobiscyclohexane carbonitrile, 2-phenylazo 2,4-dimethyl-4-methoxyvalero Examples include azo compounds such as nitrile, 2-carbamoyl-azobisinbutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, and 2,2'-azobisinbutyronitrile.

τ Polymerization methods include emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization, but bulk polymerization is preferred in order to obtain a highly pure polymer.

In the light transmitting fiber of the present invention, the refractive index value of the sheath component must be at least 1 inch smaller than that of the core component. If the difference in refractive index between the two components is less than 1%, the openings of the resulting light-transmitting fiber will be too small, making it difficult to use practically. In addition, if the refractive index of the sheath component is thicker than that of the core component, the resulting fiber will not be able to transmit the original (O). It is preferable to have good durability under such conditions.For this purpose, the sheath component polymer should have a heat distortion temperature as high as possible, preferably 70°C or higher, more preferably 90°C or higher. For this reason, it is preferable that the combined sheath component 1 has a glass transition point of 80° C. or higher.

The core-sheath dual structure transmission fiber of the present invention is produced by the following method.

(1) Core component copolymer? This composite spinning method involves melting the and sheath component polymers and extruding them into a core-sheath structure through a special nozzle.

(2) Coating method O in which a core component fiber is formed from a core component copolymer, coated with a solution of a combined sheath component 1, and then the solvent is removed from this coating layer. The core component polymer may be continuously bulk polymerized according to a method such as that disclosed in No. 131,391 and subsequently spun to form the core component fiber.

This method is effective in reducing the loss of optical transmission performance of the core component.

Effects of the Invention The light transmitting fiber of the present invention is significantly superior in heat resistance and durability compared to conventional plastic light transmitting fibers containing conventional polymethyl methacrylate or polystyrene as a core component. .

In addition, the optically transmitting fiber of the present invention has far superior optically transmitting performance compared to conventional optically transmitting fiber whose core component is polycarbonate (its optical transmission distance is only about several meters). .

Furthermore, the light transmitting fiber of the present invention has good handling properties and is extremely good in various properties.

Therefore, the optically transmitting fiber of the present invention can be used as it is in the form of a single fiber, or can be used as a three-layer structure fiber or original fiber cable with a coating layer further provided on the outer peripheral surface of the fiber. can. It is also possible to arrange a plurality of fibers in parallel and adhere or fuse them to form a sheet-like body for use.

Therefore, the optically transmitting fiber of the present invention can be used for wiring inside a car or an engine room, and therefore has extremely high industrial significance and value as it can respond to the advancement of car electronics. be.

The features and effects of the present invention as described above will be further explained with reference to Examples.

Embodiments of the invention In the examples, the optical transmission performance of the fiber is
Measurement and evaluation were carried out using the apparatus shown in Figure M4 of Publication No. 602. The measurement conditions are as follows: Interference filter (main wavelength) 650 μm Io (total length of fiber) 5 m (cutting length of fiber) 4 m D (diameter of bobbin) 190 mm In the examples, % means weight, parts means parts by weight. show.

Example 1 Methyl methacrylate 2.8 kg, maleic anhydride 1,
2) I! , tert-dodecylmerkabuta: /121
and g tert-petille pao side 0.25
P was mixed to prepare a polymerization stock solution, which was charged into a pressure-resistant polymerization reactor equipped with a 5-inch stirrer. Next, after purging the inside of the polymerization reactor with nitrogen, the temperature inside the polymerization reactor was maintained at 160°C and the temperature was increased to 70°C.
Allowed to react for minutes. The polymerization rate of the obtained polymer was 62%.

Next, this polymer was heated to 200°C with a heater and heated to 230°C.
The volatile components were removed by feeding the mixture twice into a small twin-screw extruder maintained at a temperature of .degree. C. and a pent hole pressure of 51111 HJl to obtain a colorless and transparent pellet-shaped core component copolymer. As a result of analysis by acid titration, infrared absorbance analysis, etc., the obtained copolymer consisted of 83% methyl methacrylate units and 17% maleic anhydride units, and had an intrinsic viscosity of 0.58 di/p and an intrinsic viscosity of 0.1 % methyl methacrylate and 0.1
It contained residual monomers of phosphoric anhydride.

Further, the refractive index (rLD) was 1.499, and the heat distortion temperature (Bickert softening point) was 128°C.

The monomers and mercaptan used in the core component copolymer were purified by conventional methods.

On the other hand, 2.2.2-) Lifluoroethyl methacrylate v-
), 50 parts by weight of methyl methacrylate, and 0.3 parts by weight of n-octyl mercaptan were mixed and dissolved, and then 0.3 parts by weight of azobisbutyronitrile was added as a polymerization catalyst.
0'25 parts by weight was added and dissolved, and the above mixture was poured into a cell formed by two tempered glass plates facing each other at a spacing of 5111 via a polyvinyl chloride gasket, and heated at 70°C.
It was immersed in warm water to polymerize and harden. Thirty minutes after reaching the peak temperature due to polymerization exotherm, the cell was taken out of the hot water and then heat treated in an air heating furnace at 130°C for 2 hours. After cooling, the cell was removed, and the resulting resin plate was crushed in a free/box and the Ml value (230°C load: 3.8Y) was 5.
OP/10 minutes, refractive index 1.445, heat distortion temperature 98
A sheath component polymer at ℃ was obtained.

The obtained core component and sheath component polymers were fed to a pent-type composite spinning machine having a core-sheath double structure spinning machine, and the spinning temperature was 235°C and the spinning speed was 3 m/1 nin. The film was stretched 2.0 times at 168°C and wound up.

The obtained fiber had a core component diameter of 980 μm and a sheath component thickness of 10 μm.
It was a light-transmitting fiber with a concentric structure in which the weight ratio of the core component to the sheath component was 96:4. The optical transmission loss of this optical transmission fiber was 840 dB/km, and the original signal could be sufficiently transmitted with a length of 10 ffl.

The obtained optically transmitting fiber was coated with carbon black-containing polyethylene as a first jacket using a crosshead type cable processing machine to have an outer diameter of 1.6 mm, and then carbon black-containing polyester was coated as a second jacket. An optical cable having an optical transmission loss of 865 dB/km was obtained by coating the elastomer with an outer diameter of 2.2 mm.

Cut this original cable 10n@, fix one end to a light source (650+IR interference filter used), connect and fix the other end to a photodiode, and connect the middle part of the original cable to 5m.
was exposed to a hot air heating furnace at 105°C, changes in the amount of light transmitted were tracked, and heat resistance and durability were evaluated.

As a result, even after 1000 hours had elapsed, the light intensity of this original cable decreased by only 14%, showing very little change, and showed stable heat resistance and durability.

Comparative Examples 1 to 3 For comparison, methyl methacrylate, α-methylstyrene,
Comparative Examples 1 to 30 cables were obtained in the same manner as in Example 1 except that the styrene composition was as shown in Table 1, and a polymerization stock solution was prepared.

Example 1 shows the optical transmission performance and heat resistance durability of this original cable.
The results are shown in Table 2.

As is clear from the results in Table 2 (Table 2), the optically transmitting fiber of the present invention has a low light loss sufficient to enable communication of 107,711-length optical signals, and also has excellent heat resistance and durability. was.

On the other hand, those other than the present invention shown in Comparative Examples 1 to 3,
Heat resistance and durability were unsatisfactory.

Regarding the bending resistance of light transmitting fibers, see Example 1 and Comparative Example 1.
~3 All were strong without any problems.

Example 2 To 100 parts of a 20% mixture, 0.005 parts of di-tert-butyl peroxide and 0.15 parts of n-octyl mercaptan were added, and the polymerization stock solution prepared was poured into a glass tube with an inner diameter of 6 mm. After charging, it was cooled and solidified in a dry ice-methanol refrigerant, replaced with nitrogen, and sealed in a vacuum tube.

Next, this sealed glass tube was placed in an oil path bath at 160°C and polymerized for 1 hour.

The polymerization rate of the obtained polymer was 68%.

After dissolving this polymer in chloroform, the polymer was precipitated in methanol, filtered, and dried to obtain a colorless and transparent powder. °This powder consists of 88% methyl methacrylate units and 12 maleic anhydride units, and has a yield of 0.79 dl/p.
It had an intrinsic viscosity of , and a Bicat softening point of 126°C. Further, the amount of residual monomer was 0.1% or less.

An original cable was obtained in the same manner as in Example 1 except that this powder was used as a core component polymer.

The optical transmission loss of the original cable obtained was 26 in 650 hours.
Example 3 A system consisting of a storage tank, a continuous feed pump, a reaction tank equipped with a paddle spiral stirrer, a reactant Sakaide pump, and a volatile matter separator was used in series. The component polymers were manufactured. The internal volume of the reaction tank was 40 cm, and a twin-screw one-vent extruder was used as the volatile matter separator.

The stock solution for core component copolymer No. 1 was circulated in advance through a 0.1 μm polytetrafluoroethyl L/7# filter (Fluorobor FPOIO manufactured by Sumitomo Electric Industries, Ltd.) to remove impurities.

The composition of this combined stock solution is 76 parts of methyl methacrylate, 17 parts of maleic anhydride, 7 parts of toluene, 0.2 parts of tert-butyl mercaptan, and 0.0017 parts of di-tert-butyl peroxide. A feed pump was used to feed the reactor into a reaction tank with an internal pressure of 7 kll/cm gauge pressure and a temperature of 165°C.
Filtration was carried out by stacking 31 μm polytetrafluoroethylene filters (Fluorobor FPOIO manufactured by Sumitomo Electric Industries, Ltd.), and the continuously supplied mixture was thoroughly stirred in the reaction tank. Polymerization occurred while

The average residence time of the mixture in the reaction tank was 4.4 hours, and the average polymerization rate was 53% by weight.

The reaction mixture was heated from 165°C to 210°C between the reactor and the volatile separator.

The temperature of the vented extruder, which also serves as a volatile separator, is 240℃ at the vent section, 245℃ at the extrusion section, and the degree of vacuum at the vent section is 5.
yxxHl.

The core component polymer discharged from the vented extruder was introduced into a spinning head directly connected thereto.

Separately, a sheath component polymer is introduced into a spinning head from another extruder installed in parallel with the above-mentioned pet/to extruder, and here the core component polymer and the sheath component polymer form a core-sheath structure. Composite spinning was carried out at 240°C.

The sheath component polymer used was the same as in Example 1. The residual amount of monomer in the core component copolymer is 0.1% or less, the refractive index is D1.496, the intrinsic viscosity is 0.62 di/p,
90 units of methyl methacrylate, 1 unit of maleic anhydride
It consisted of 0%.

In addition, the ratio of the core component to the sheath component of the obtained core-sheath structured fiber was 90:10, and the outer diameter was 1. The optical transmission property of the fiber thus obtained was 810 dB/km for light with a wavelength of 650 μm.
It was extremely good. The cable made of this composite fiber showed extremely excellent heat resistance and durability, with a decrease in the amount of transmitted light of only 18 degrees after heat treatment at 105° C. for 1000 hours.

Claims (1)

[Claims] ■ Consists of 67 to 99% by weight of methyl methacrylate units and 1 to 33 maleic anhydride units, and has an intrinsic viscosity of 0.35 to 2.0 d when measured in chloroform at 25°C.
7! /J, a core component comprising a methacrylic resin with a residual monomer content of 1.0 weight or less, and a core component that covers the core component and has a refractive index of 1% higher than the refractive index of the core component copolymer. and a sheath component made of a polymer having a low refractive index. (2) The light transmitting fiber according to claim 1, wherein the sheath component polymer is a transparent polymer having a glass transition point of 80° C. or higher. (ii) The sheath component polymer is one selected from the group consisting of a polymer of fluorinated alcohol ester of methacrylic acid, vinylidene fluoride-tetrafluoroethylene copolymer, and polymethyl methacrylate. , a light transmitting fiber according to claim 1.