JPS60205403A - Plastic optical fiber having superior heat resistance - Google Patents

Abstract

PURPOSE:To provide superior heat resistance to a plastic optical fiber having a core-sheath structure by using a copolymer of alkyl (meth)acrylate with an alpha- methylstyrene compound as a core component resin. CONSTITUTION:An alpha-methylstyrene compound having a methyl group at the alpha- position for improving oxidation resistance and heat resistance is copolymerized with alkyl (meth)acrylate. For example, a mixture consisting of 3 parts methyl acrylate, 27 parts methyl methacrylate, 70 parts alpha-methylstyrene, 0.05 part 1,1'- azobis(cyclohexane-1-carbonitrile) and 0.05 part n-butylmercaptan is polymerized at 100 deg.C and fed to a multistage bent extruder to remove unpolymerized alpha- methylstyrene. The resulting polymer is introduced into a composite melting device, where the polymer as a coer component resin and a copolymer consisting of 85mol% vinylidene fluoride and 15mol% tetrafluoroethylene as a sheath component resin are subjected to composite melt spinning to obtain a plastic optical fiber having a core-sheath structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a plastic optical fiber having excellent heat resistance and oxidation resistance, which is characterized by using an improved core component resin.

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"Compared to inorganic glass 7 eyeglass fiber, especially quartz glass fiber, 7-7 steel fiber has less flexibility even if it has a population of f6, and has a high amount of eaves: jt or 1." Because it is easy to obtain optical fibers, there is less connection loss with optical
It has the characteristic of being extremely inexpensive due to its f-capacity, and it is short-range r! ! Used for transmission systems.

t, #) L tx or la plastic (pudical 7a, f bar has the disadvantage that the transmission loss increases to 11) at operating humidity above 80~Il, so automatic 1 (,
When used in moving objects such as 4" aircraft and ships, its use is limited due to its 1.P capacity temperature, which prevents the expansion of the use of plastic fibers. Therefore, many attempts have been made to improve the heat resistance of plastic fibers.

For example, JP-A-58-54404, JP-A-58-
221808 proposes the use of aryl methacrylate or alkyl methacrylate as the core component resin. In order to improve the heat resistance of plastic optical fibers, these materials use alkyl methacrylates with a large number of carbon atoms and bulky alkyl groups as core component resins, and alfurs with aromatic rings as alfurs constituting the esters. The glass transition point (T,) of the polymer was determined using aryl methacrylate produced by
It is based on the technical philosophy of improving the However, this technical idea was developed as the core component resin of Plastic Optical 7 Aino 5-.
Alkyl methacrylates as exemplified in Japanese Patent Publication No. 8978, Japanese Patent Publication No. 53-42261, etc.;
Among the aryl methacrylates exemplified in Japanese Patent No. 49415, only 14 aryl methacrylates having a high T when made into a polymer are used.

According to the studies of the present inventors, when a polymer of alkyl methacrylate having a bulky alkyl group with a large number of carbon atoms as described above or a polymer of aryl methacrylate having an aromatic ring is used for plastic optical fibers, It has been found that even if a stretching treatment is performed, the flexibility and bending properties are poor, and it is almost impossible to make the material suitable for practical use.

=)i, 4';i Japanese Patent Publication No. 58-65402 exemplifies the use of a copolymer of Nisder methacryoctatate and a styrene derivative as a core component resin.

This is because a polymer having a substituent on an aromatic ring has a high T, tg. It is based on the technical idea of using styrene derivatives that can However, this technical concept is based on the use of styrene derivative polymers and their co-polymer exemplified in JP-A-49-1276576J as core component resins of blast optical fibers.
This simply means that the one with the highest T) among the n% bodies was used.

Furthermore, when a lk polymer consisting of styrene or styrene derivatives is used as a core component resin, water, atoms, and halogen atoms at the α position are extremely easily oxidized, and oxidation progresses during use, resulting in yellowing. It has a serious drawback that the transmission loss increases to a large I11. Therefore the length 1υj
It has the disadvantage that it cannot be used for intermediate applications, especially at high temperatures of 80°C or higher.

[(development of) invention]

The inventors of the present invention have conducted intensive studies to improve the fatal defects of plastic optical fibers according to the conventional technology as described above. , developed a plastic optical fiber with dramatically improved oxidation resistance, and completed the present invention.

In other words, the present invention provides IH using a copolymer of a (meth)acrylic acid alkyl ester and an α-methylstyrene compound as a core component resin in a plastic A-butical fiber having a core-sheath structure. Regarding plastic optical fibers with excellent heat resistance.

The present invention uses an α-meil styrene thread compound having a methyl group at the α-position to improve the m-resistance and heat resistance of the fR polymer, and further improves (meth)'rcryl I'R
By combining 1n alkyl esters,
"11 f'; It is based on the technical idea of improving mechanical properties such as A property and bending.

In addition, in Unknown J'llll j4, (meth)acrylic acid alkyl ester means acrylic acid alkylene ester and methacrylic acid alkylnisder.

[Practice of the invention III! 1] The term methacrylic alkyl ester used in this invention is a varnish produced from an alcohol having 7 argyl groups with a prime number of 1 or more and methacrylic. methyl acrylate, ethyl acrylate,
Examples include, but are not limited to, acrylic (it alkyl esters such as acrylic n2-propyl), methacrylic acid alkyl esters such as mebble methacrylate, eyl methacrylate, 11-propyl methacrylate, and butyl methacrylate.

As the α-methylstyrene compound used in the present invention,
Ritoeke α-methylstyrene, p-fluoro-α-methylstyrene, p-chloro-α-methyl7-restyrene, p-
Examples include, but are not limited to, methyl-α-methylstyrene and p-trifluoromethyl(-methylstyrene).

All or some of the hydrogen atoms in the methanoacrylic acid alkyl ester or α-methylstyrene compound used in the present invention may be substituted with deuterium atoms and/or fluorine atoms.

In the copolymer of (meth)acrylic acid alkyl ester and α-methylstyrene compound used in the present invention, the type of each monomer and the lii ratio satisfy the desired heat resistance, numerical aperture, mechanical properties, etc. You can select and use it as appropriate. From the viewpoint of J-music, a copolymer of acrylic acid alkyl ester, methyl methacrylate, and α-methylstyrene is preferable, and from the viewpoint of improving heat resistance, α-methylstyrene content is preferably 311 mol. %
The content is preferably at least 40% by mole, more preferably at least 40% by mole, and particularly preferably at least 507% by mole. Examples of the acrylic alkyl ester include methyl acrylate, ethyl acrylate, etc.
Qf is preferable in terms of flexibility, direction of bending, etc.

One body of +1 used in the present invention is removed by removing impurities in a distiller with a high distillation efficiency 41, or by further distilling after performing appropriate pretreatment to remove dust, transition gold, coloring impurities, etc. It is a highly pure memorial body.

Any combination initiator used in the present invention may be selected depending on the desired fraction, polymerization temperature, and if1 combination rate, such as azobisisobutyronitrile, 1.1'
-Azobis(diclohexane-1-carbonitrile,
Examples include benzoyl peroxide and t-butyl peroxide. There is no particular limitation on the use of h1, and it is sufficient to use an appropriate polymerizable funtrol within the range that can be used.

The molecular weight regulator used in the present invention may be selected from any arbitrary one as long as it does not have an adverse effect such as coloring on the final polymer, such as n-butyl mercaptan, t-butyl mercaptan, n-dodecyl mercaptan, Examples include t-dodecyl mercaptan.There are no particular limitations on its use, and it is preferable to use it so that the weight average molecule ut of the final polymer is in the range of 80,000 to 1,500 units.

Polymerization initiator and molecule used in the present invention! As a charging method for tA saving, it is preferable to dissolve it in a small amount of monomer under environmental conditions free from dust and the like and charge it into a polymerization vessel, since there are few companies using it.

In order to avoid unexpected contamination with dust, etc., use a distillable polymerization initiator such as t-butyl peroxide or n-octyl azobutane, and use a distillable molecular weight regulator such as n-butyl mercaptan. It is preferable to use mebutyl mercaptan or the like, and when such a combination initiator or molecule is used with a regulator, it becomes possible to employ a distillation charging method. It is also possible to add a small amount of polymerization initiator and molecular weight regulator to the polymer, and then pass it through a filter and charge it into the mixing vessel. The above method is sufficient for purifying the simple compound, polymerization initiator, and Shibunshacho strawberry agent used in the process, but apart from preventing the contamination of dust,
I+ which produces polymers above all else? combination d; & in 1
-J The method of thoroughly removing dust is to remove it, and as a method for this purpose, the patent application filed in 1986-4 by the present inventors
11. As stated in the specification of No. 2761, the specification of Japanese Patent Application No. 58-42762, etc. However, it is preferable to remove dust in the polymerization vessel to the extent possible by rifling before polymerization.

From the viewpoint of light transmission efficiency, the core component resin used in the present invention is preferably polymerized in bulk jl<legal.

Mata α-methylstyrene compounds have poor radical homopolymerizability and poor copolymerizability under general conditions, so if it is necessary to produce a copolymer with a uniform composition, if (
It is also possible to adopt a method in which methanoacrylic acid alkyl ester is polymerized at 111 times. In addition, the existing single α-methylstyrene compound is devolatilized and removed using a vent extruder to obtain the desired compound. Can move through polymers.

In the present invention, the material forming the sheath structure is not particularly limited as long as it has a lower refractive index than the core component methyl methacrylate polymer and has relatively excellent enclosing properties, and has a desired numerical aperture. , any one may be selected depending on the spinnability. Examples of the sheath component resin that forms such a sheath structure include fluorine-containing polymers, specific examples of which include homopolymers or copolymers with tetrafluoroethylene, hynylidene fluoride, and hexafluoro-tetrapropylene; Examples include homopolymers of fluorinated alcohol esters of methacrylic acid, and copolymers of these with methacrylic esters such as methyl methacrylate, acrylic esters such as methyl acrylate, acrylic acid, methacrylic acid, and the like. Among these fluorine-containing 1R combinations, price, manufacturing method, spinnability,
From the viewpoint of heat resistance, etc., a co-11 polymer of tetrafluoroethylene and vinylidene fluoride is preferable, and a copolymerizable polymer is added as a third component to these monomers to form a co+11 polymer.
Ij combined co+r (combination is also preferable. On the other hand, from the viewpoint of optical transmission efficiency, f of the fluorine-containing Nff1 combined
homopolymerization of fluorinated alcohol ester of methacrylic acid (preferably, methacrylic i'42 Noah
IH, IH, 5H-4 copolymer of methacrylate-like lopentyl methacrylate and methacrylate-like lopentyl methacrylate, IH
, IH, 2H, 2H-Hebutadecafluorodecyl methacrylate and methyl methacrylate Ju Ilr synthesis 1
A copolymer of 2,2,3,5.3-pentafluor 40propyl methacrylate and meblutomethacrylate is particularly preferred. In addition, the fluorinated alcohol Nisder of methacrylic acid and the covalent value of methyl methacrylate n + iJ flll:
Co-1 (co-1) which is copolymerized with the sixth single compound II "Japan" is also preferable.

The plus book i physical fiber of the present invention has a core component 1σV obtained by 'F'j j'sj as described above.
! III and a sheath component resin.

As for the manufacturing method, there are commonly used methods such as spinning a core component resin and then coating the sheath component resin thereon, or joining and melt-spinning the core component resin and the sheath component resin. It can be adopted without particular limitation.

The plastic optical fiber thus obtained has a core-sheath structure with a sheath having a thickness of 5 to 20 μm, and preferably has a diameter of 0.6 to 6 rrn from the viewpoint of connection with the fiber and connection with a light source. , 0.5
-2 threshold is more preferable, and 0.8-1.2 mm is particularly preferable.

The plastic optical fiber obtained as described above uses the above-mentioned resin with excellent heat resistance and oxidation resistance as the core component resin, so compared to conventional plastic optical fiber, it can withstand temperatures of 80°C or more. Since there is no decrease in optical transmission loss even when used for long periods of time in high-temperature products, it is possible to greatly expand the applicable temperature range, and as a result, it is possible to use the product in automobiles, ships, aircraft, and robots.
r Tohe (1) J function can be made tiJ function, and furthermore, the range of 11 Yukawa to ii + i bt tc inside the building can be dramatically expanded.

Hereinafter, the optical fiber of the present invention will be explained based on an example. Evaluation was made using the transmission loss calculated from the following equation from (0) and the output intensity f, [).

Transmission loss (dB/km) = 10 log
(I/Io)/L Example 1 6 parts of methyl acrylate (parts of jfj j+, hereinafter the same)
, 27 Ffl+ of methyl methacrylate, 70 Ffl+ of α-methylstyrene, 501 jus of a mixture of 40/15 parts of Ll'-A Polymerization made of glass lining: Charge in bulk to t3, 1
When polymerization was carried out at 00°O, the polymer concentration was changed to 50% polymer solution overnight.

The obtained polymer solution is supplied to a multistage vent extruder to remove unpolymerized α-methylstyrene, and then introduced to a composite melting device, where 85 mol% of vinylidene fluoride and 15 mol% of tetrafluoroethylene are added as sheath component resins. A plastic optical fiber having a core-sheath structure with a diameter of 1 mm was obtained by composite melt spinning using a copolymer consisting of the following.

The transmission loss at 100°0 was measured using the obtained plastic optical fiber.

The results are shown in FIG. As shown in Figure 1, 660
The transmission loss in nm was 200 dB/km.

Examples 2 to 7 The sheath component resin, polymerization method, demonomer removal, and composite melt spinning were the same as in Example 1, but only the single shell composition when producing the core component resin was changed as shown in Table 1. , produced plastic optical fiber.

Transmission (H loss) at 100 qD and 660 nm was measured using a plastic optical fiber that had been erected. The results are shown in Table 1.

Example 8 Plastic A butical fiber was produced in the same manner as in Example 1 except that a copolymer consisting of perfluorinated L-butyl methacrylate 90111fi, 8 parts of methyl methacrylate, and 2 parts of methyl acrylate was used as the sheath component resin. I got it.

When we measured the transmission loss at 100% at 66 onm using the obtained plastic optical fiber, we found that
It was 195 dB/km.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between transmission loss and wavelength at 1oooO of the plastic optical fiber obtained in Example 1.

Claims (1)

[Scope of Claims] 1. In a 7-last optical fiber having a core-sheath structure, (meth-1 acrylic acid alkyl ester and α-methylstyrene compound common name) A butyl fiber, a plastic with excellent heat resistance, characterized in that it can be used as a polymer. Special r+'t' If t of request
lfi No. IL & Plastic A butical fiber. 3+? 11. The plastic A physical fiber according to claim 1, wherein the J marking sheath 41 is formed from a fluorine-containing claw assembly. 4. The plastic optical fiber according to claim 1, wherein the tp+1 sheath structure is formed from a copolymer of tetrafluoroethylene and vinyl fluoride. 5. Special Iyl-B, wherein the sheath structure is formed from a homopolymer or copolymer of fluorinated alcohol ester of methacrylic acid and (meth)acrylic acid ester or (methaneacrylic acid); range 1
Plastic optical fibers as described in Section. 6[7fJ (meth)acrylic ester fQb<C methyl meth)acrylate Claim 5 m
l plastic A butical afiba-0