JPS63249112A - Optical fiber - Google Patents

Abstract

PURPOSE:To obtain a shell material having a low refractive index, high transparency, superior mechanical characteristics, and high heat resistance by using a specified long-chain fluoroalkyl (meth)acrylate and a specified short-chain fluoroalkyl (meth)acrylate as a base material. CONSTITUTION:A compsn. consisting of 1-50wt.% long-chain fluoroalkyl (meth) acrylate expressed by formula I, 50-90wt.% short-chain fluoroalkyl (meth) acrylate expressed by formula II, 1-20wt.% crosslinking monomer having >=2 polymerizable functional groups in a molecule, and 0.1-10wt.% photopolymn. initiator, is used for a photosetting compsn. constituting a shell component. In formulas, Y is H or CH3; X is H or F; l is an integer >=1; n is formula I is an integer 6-12; n in formula II is an integer 1-3. By this constitution, optical fiber having superior heat resistance and superior bending strength is provided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has a core made of quartz, polymethyl methacrylate, polystyrene, polyglutarimide, polycarbonate, or other plastics, and a sheath made of a photocurable resin composition. This invention relates to an optical fiber made of a hardened material.

[Conventional technology]

The physical properties required for optical fiber sheath materials include having a lower refractive index than the core material, good transparency and heat resistance, excellent mechanical properties, and good compatibility with stone. . Up until now, the sheath materials that meet these requirements have been shown in Japanese Patent Publication No. 43-3878, for example, using the general formula % (%) (in the formula, X is H, ? or OL, and n is 1 to 6). integer,
(m is an integer from 2 to 10) as a polymer or copolymer of fluoroalkyl methacrylate as a T-sheath material, and trifluoroethyl (meth) as shown in JP-A-49-107730. A sheath material made of an acrylate polymer, a sheath material made of an α-fluoroacrylate polymer as shown in JP-A No. 59-228604, and a sheath material made of an α-fluoroacrylate polymer as shown in Japanese Patent Publication No. 53-216750. Those using a copolymer of vinylidene fluoride and tetrafluoroethylene are known.

[Problem that the invention seeks to solve]

Polymers or copolymers of fluoroalkyl methacrylate and polymers of trifluoroethyl methacrylate are poor quality polymers that lack transparency and have a low refractive index, but their mechanical properties and heat resistance are not sufficient and they cannot be used with light. It is insufficient as a fiber sheath material.

Vinylidene fluoride polymer has excellent mechanical properties, but this polymer is crystalline, and even if it is a transparent film, when exposed to a high temperature atmosphere, crystallization will be promoted and it will become opaque, making it difficult to use as an optical fiber. It has the disadvantage that it degrades the optical transmission characteristics of .

α-Fluoroacrylate polymer film has excellent mechanical properties, heat resistance, transparency, etc., but has a strong tendency to thermally decompose when subjected to melt spinning, which causes problems in the optical fiber manufacturing process. The problem is that it is easy to cause

[Means to solve the problem]

In view of the above-mentioned current situation, the present inventors completed the present invention as a result of studies aimed at providing a sheath material with a low refractive index and excellent transparency, mechanical properties, and heat resistance for film-like materials. The gist of this is that crosslinkable monomers having at least two or more polymerizable functional groups in one molecule based on long-chain fluoroalkyl (meth)acrylates and short-chain fluoroalkyl (meth)acrylates, and The optical fiber has a sheath material R1 formed by adding a polymerization initiator, coating the core surface with the composition, and curing the core by irradiating it with light.

The long-chain fluoroalkyl(meth)ac+)V-to monomer used in the present invention has a structure represented by the general formula (1) as described above, and specific examples include, for example, 1.1.2. .2-Tetrahydroperfluorododecyl (meth)acrylate, f, 1.2.2-Tetrahydroperfluorodecyl (meth)acrylate, 1.1
-dihydroperfluoroptyl (meth)acrylate and the like are exemplified. The long-chain fluoroalkyl (meth)acrylate mentioned above can be mentioned, and the content of the compound is preferably less than 10% by weight in the composition for forming a sheath material. The resulting cured polymer has a high refractive index, and it is difficult to make the mechanical properties too high, impairing its suitability as an optical fiber sheath material. The compatibility with other components such as polyfunctional monomers and photopolymerization initiators deteriorates, and as a result, the cured polymer becomes cloudy, impairing its suitability as a sheath material.

Short-chain fluoroalkyl (
Specific examples of meta) azirylate include the column (Ha2,2,
3.3-Tetrafluoropropyl (meth)acrylate, trifluoroethyl (meth)acrylate% 2.2
．． & 3.5-pentafluoropropyl (meth)acrylate, 1-trifluoromethyl-2,2,2-1-
Lifluoroethyl (meth)acrylate, 1-trifluoromethyl-1,2゜2.2-tetrafluoro a(meth)
acrylate, 2,2.44.4.4-hexafluorobutyl(meth)acrynote, 1-methyl-42,he4
．． 4.4-Hexafluorobutyl (meth)acrynote, 1-dimethyl-2,2,5,3-tetrafluoropropyl (meth)acrylate, 1.1-dimethyl-2゜2
, 3.4.4.4-hexafluorobutyl (meth)acrylate, etc., and the content of these short-chain fluoroalkyl (meth)acrylates in the photocurable composition is 50 to 90% by weight. It is desirable to use it within a range of 11%. A composition containing less than 50% by weight and 1t% will be less compatible with other components such as polyfunctional monomers and photopolymerization initiators, resulting in turbidity in the cured polymer and impairing its suitability as a sheath material. Conversely, a cured polymer obtained from a composition containing 90% by weight or more of the compound has a high refractive index and cannot have a large difference in refractive index with the core material, making it easy to form an optical fiber with a small number of openings. Practical characteristics of optical fiber deteriorate.

That is, the long chain fluoroalkyl (meth)acrylate component serves to lower the refractive index and improve the mechanical properties of the cured polymer, while the short chain fluoroalkyl (meth)acrylate component serves to lower the refractive index and improve the mechanical properties of the cured polymer.
The acrylate component functions to improve the compatibility of polyfunctional monomers, photopolymerization initiators, etc. and to improve the transparency of the cured polymer.

The polyfunctional crosslinkable monomer used in the present invention includes, for example, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, neo Pentyl glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, hydroxypivalic acid ester neopentyl glycol diacrylate, hydroxypivalic acid ester neopentyl glycol derivative diacrylate, neopentyl glycol modified trimethio-propane diacrylate 3 Trimethylolpropane triacrylate, pentaerythritol triacrylate as functional ones, dipentaerythritol monohydroxypentaacrylate V as pentafunctional ones
- and hexa-functional ones include dipentaerythritol hexaacrylate and the like. The above polyfunctional crosslinking monomers can be used alone or in combination of two or more, and the proportion in the total composition is 1 to 20% by weight/i%.
It is desirable to use it within the range of . A cured polymer made from a composition having a weight of less than 1 weight will not provide a sufficient crosslinking density, while a composition having a weight of 20 weight or more will result in poor compatibility and a turbid Dt.

As the photopolymerization initiator, various kinds of materials that are generally used as initiators and sensitizers for ultraviolet curable paints can be used.
For example, benzoin, pentuin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, 2-methylbenzoin.

Examples include benzophenone, Michler's ketone, benzyl, benzyl dimethyl ketal, benzyl diethyl ketal, anthraquinone, methyl anthraquinone, diacetyl, acetophenone, diphenyl disulfide, anthracene, and those used in combination with small amounts of sensitizing aids such as amines.

The amount of these photopolymerization initiators used is 0 in the photocurable composition.
．． It is preferably contained in a range of 1 to 10 parts by weight.

Further, it is desirable to add 5 to 50 weight Q 1 of an oligomer or polymer having good compatibility with the monomer composition to the sheath component resin composition used in the present invention in order to adjust the viscosity of the composition.

Further, additives other than those mentioned above can be mixed into the sheath component resin composition used in the present invention within the allowable range of curing conditions, compatibility, etc.

For example, by adding an oligomer component containing a polymerizable unsaturated group, it is possible to adjust the viscosity e of the resin composition to 1.1 and simultaneously improve the curing speed. It is also possible to add an improving agent to improve the adhesion to the optical fiber core component.

[Effects of the present invention].

The optical fiber of the present invention uses a conventional fluoroalkyl methacrylate polymer as a sheath material, and has superior heat resistance and bending resistance compared to optical fibers obtained by melt-spinning cores made of other polymers with good light guiding properties. In addition, since the composition for forming the sheath component is a photopolymerizable resin that is cured in a short time by ultraviolet rays, the productivity of optical fibers is high and the production management thereof is easy.

The present invention will be explained in detail below with reference to Examples.

Example 1 20 parts by weight of 1.1.2.2-tetrahydroperfluorodecyl acrylate as a long-chain fluoroalkyl (meth)acrylate monomer, 80 parts by weight of trifluoroethyl acrylate as a short-chain fluoroalkyl (meth)acrylate monomer Parts by weight, 7 parts by weight of 1,6-hexanethiol diacrylate as a polyfunctional monomer, and benzyl dimethyl ketal (manufactured by Ciba Geigy) as a photopolymerization initiator.
A photocurable resin composition CAI was obtained by mixing 3 parts by weight of Irgacure (trade name: Irgacure 651) at room temperature. This resin composition [A
] was cast onto a glass plate to a thickness of 100 μm and tightly covered with a polyester film to prepare a sample. This sample was exposed to light at B OW / cm for about 1 second using an ultraviolet exposure device f fr: equipped with a high-pressure mercury lamp to obtain a cured product.

This cured product was a transparent and flexible film with a refractive index of 1.589. Even after this film was treated at t-150° C. for 100 hours, the transparency did not change.

A quartz core fiber with an outer diameter of about 200 μm was passed through a coating bath made of the photocurable resin composition [A] at a speed of about 1 m/sec, and was exposed to an ultraviolet light exposure device with a built-in high-pressure mercury lamp at 80 W/cm. A polymer-clad quartz optical fiber with an outer diameter of 300 μm was obtained by irradiating ultraviolet light at an irradiation energy level of m. This optical fiber had a good optical transmission loss of 84 B/km at a wavelength of 850 nm, and the transmission loss did not change even after being treated at 150° C. for 20 hours.

Examples 2 to 6 A photocurable composition was prepared by adding the photopolymerization initiator used in Example 1 to the photocurable composition shown in Table 1. Example 1
A film-like cured product was obtained in the same manner as above. The refractive index of this film-like cured product is also shown. The films of all photocurable resin compositions were transparent and flexible.

Similarly to Example 1, a core clad optical fiber was made by coating quartz fiber and its optical transmission loss, heat resistance, etc. were evaluated. As in Example 1, the optical fiber had low transmission loss and had excellent heat resistance characteristics. 'r: I confirmed that it was 4 meters higher.

Table 1 Example 7 A polycarbonate core fiber with an outer diameter of about 1000 μm was taken through a bath made of the photocurable resin composition of Example 3 at a speed of about 1 m/sec using an ultraviolet i exposure device equipped with a built-in high-pressure mercury lamp. , an optical fiber with an outer diameter of 1050 μm was obtained by irradiation at an irradiation energy level of 80 W/cWK. This optical fiber has a loss of 10 at a wavelength of 770 nm.
00dB/km. This was heated to 130℃ for 300 minutes.
When the loss is measured after time treatment, it is 1 at a wavelength of 770 nm.
The speed was good at 0.050 an/km.

An optical fiber with an outer diameter of 300 μm was obtained by using vinylidene fluoride resin from a quartz core fiber with a comparative exception diameter of 200 μm. This optical fiber has a loss of 100 at a wavelength of 800°C.
4B/km, but when this was treated at 100°C for 100 hours, the loss was 3o an/km at a wavelength of 800 nm.
km.

Claims (2)

[Claims] (1) The sheath component of an optical fiber with a core-sheath structure is (a) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) [In the formula, Y is H or CH_3 X is H or F l is 1 or more Integer n is an integer from 6 to 12] At least one long-chain fluoroalkyl (meth)acrylate represented by (b) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (2) [In the formula, Y is H or CH_3, X is H or F n is an integer of 1 to 3] At least one short chain fluoroalkyl (meth)acrylate (c) Crosslinkable having at least two or more polymerizable functional groups in one molecule An optical fiber comprising a cured product of a photocurable composition comprising at least one monomer (d) photopolymerization initiator. (2) 1 to 50% by weight of a long-chain fluoroalkyl (meth)acrylate represented by general formula (1) and 50 to 90% by weight of a short-chain fluoroalkyl (meth)acrylate represented by general formula (2) as a photocurable composition Weight% and crosslinkable monomers having two or more polymerizable functional groups in one molecule 1 to 20
% by weight and a photopolymerization initiator from 0.1 to 10% by weight.