JP2570217B2 - Optical transmission fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a light source comprising an active energy ray-curable resin composition which gives a tough and transparent cured resin having a low refractive index by irradiation with an active energy ray such as an electron beam or an ultraviolet ray. Related to transmission fiber.

[0002]

2. Description of the Related Art Fluoropolymers have been used as highly functional materials in various fields because they generally have high chemical resistance, weather resistance, water / oil repellency, surface lubricity and the like. In recent years, its optical properties, that is, low-refractive-index properties, have been noted,
Use of optical transmission fibers as sheath materials and low-reflection coatings has been active.

[0003] Optical transmission fibers are broadly classified into inorganic glass-based and synthetic resin-based ones, each of which is composed of a core portion having high transparency and a high refractive index, and a sheath portion having a relatively low refractive index. I have. Conventionally, as a method of forming a sheath portion,
Coatings of silicone-based compounds or fluoropolymers with a low refractive index have been proposed and practiced. For example, 1) a method of applying a silicone resin composition to a drawn quartz core wire and forming a sheath portion of the silicone resin by thermosetting, 2) a core material such as poly (methyl methacrylate) or poly (styrene). And a copolymer of a fluorinated alkyl group-containing (meth) acrylate and a fluorinated alkyl group-containing (meth) acrylate obtained by a polymerization method such as solution polymerization, bulk polymerization, or emulsion polymerization. Coalescing or poly (tetrafluoroethylene),
A method of spinning a composite with a fluorinated polymer such as poly (vinylidene fluoride / tetrafluoroethylene) or poly (vinylidene fluoride / hexafluoropropylene) to form a sheath portion composed of a fluorinated polymer (Japanese Patent Publication No. 43-43) No. 8978, JP-B-56-8321, JP-B-56-8322, JP-B-56-8323, JP-A-59-84203, JP-A-59-84204, JP-A-59-98116, JP-A-59-147011, JP-A-59-204002
No.), 3) A quartz or plastic core formed into a fibrous form is coated with a melt or solution of a fluoropolymer such as poly (vinylidene fluoride / tetrafluoroethylene) to form a sheath. Method (Japanese Patent Publication No. 53-21660)
No. 56-41966).

However, among these proposals, the silicone resin described in 1) is excellent in heat resistance, but is poor in mechanical strength and oil resistance. In particular, the silicone resin swells when immersed in mineral oil or the like, and changes in refractive index or changes from the core wire. There is a disadvantage that peeling occurs. For this reason, optical transmission fibers using a silicone resin as a sheath material are limited in application, and are unsuitable for use in oils such as transformers and thyristors.

[0005] In addition, since the silicone resin composition before curing has a short pot life and increases in viscosity over time, the coating speed and the temperature of the atmosphere are controlled in order to apply a constant thickness to the core wire. There was a work drawback that had to be done.

[0006] Further, the refractive index of silicone resin is limited to about 1.40, and it is insufficient in performance as a sheath material of a large-diameter optical transmission fiber required with an increase in communication capacity. There is a disadvantage that.

On the other hand, the fluoropolymers described in 2) and 3) have a low refractive index of about 1.36, so that
The sheath material of the large-diameter optical transmission fiber is more suitable than the silicone resin.

However, in the conventional method of forming the sheath portion with a fluoropolymer as described in 2) and 3), the core wire and the sheath portion are subjected to composite spinning at a high temperature, or into a fibrous form. Since the shaped core is coated with the melt or solution of the fluoropolymer, the diameter of the core and the thickness of the sheath also tend to be non-uniform.

For this reason, there is a problem that light is scattered at a locally bent portion at the interface between the core portion and the sheath portion, and transmission loss is increased. Further, in the optical transmission fiber formed by these conventional methods, the adhesion between the core portion and the sheath portion is not always sufficient, and delamination is easily caused by various external factors such as bending, pressure change, temperature change, and the like. , Durability and the like.

Further, in the method for producing an optical transmission fiber by applying a melt or solution of a fluoropolymer as described in 2) and 3), it takes a long time to cure the sheath, and The coating method has drawbacks in productivity, safety, economy, etc., particularly in the necessity of completely removing the solvent out of the system, which complicates the production process and equipment.

In view of these problems, recently, attention has been paid to rapid curing of acrylate monomers by a photopolymerization reaction, and the use of highly fluorinated monoacrylates and trifunctional or higher acrylate monomers as a crosslinking agent has been reported. There is a proposal for an optical transmission fiber using an ultraviolet-curable resin made of
4,511,209).

However, according to the findings of the present inventors, the UV-curable composition comprising only a monomer component as proposed in the present invention has too low a viscosity and cannot be applied to the core wire by the current production method. There are drawbacks. Furthermore, since the cured resin after the irradiation of the ultraviolet rays has poor transparency, there is a problem that the optical transmission fiber obtained has a large optical transmission loss.

[0013]

DISCLOSURE OF THE INVENTION The present invention relates to a sheath material which is satisfactory in terms of performance such as mechanical strength and adhesion, and is satisfactory in terms of productivity, safety, economy and the like in the production of optical transmission fibers. It is another object of the present invention to provide an optical transmission fiber having a sheath material having a lower refractive index, which enables a higher numerical aperture and a larger diameter.

[0014]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, as described below, a certain fluorine-containing polymer and a certain fluorine-containing acrylate or methacrylate [ And a combination thereof, referred to as a (meth) acrylate], and a resin composition comprising a non-fluorine-based (meth) acrylate monomer, which is cured by an active energy ray. Compared to the material, it was found to be superior in mechanical strength, adhesion to the core wire, and transparency.

Furthermore, in the resin composition according to the present invention, the viscosity of the resin composition can be arbitrarily controlled by adjusting the degree of polymerization and / or the content of the fluoropolymer. A higher numerical aperture of the optical transmission fiber can be easily achieved by easily preparing a resin composition having a viscosity corresponding to the required coating thickness, and further increasing the fluorine atom content in the fluoropolymer.
The inventors have discovered advantages such as the possibility of increasing the diameter and obtaining a sheath material having a refractive index of about 1.33, and have completed the present invention.

That is, the present invention provides the following general formula:

[0017]

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(Wherein, Rf is a fluorinated aliphatic group having 1 to 20 carbon atoms, n is 0 or an integer of 1 to 6,
Is H, CH ₃ or F. ) And a mono (meth) acrylate (B) having one or more kinds of mono (meth) acrylates having an ester substituent having 3 or more carbon atoms (B). Combined (I), the following general formula

[0019]

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(Wherein Rf, n and R are the same as those described above), and one or more ester substituents having three or more carbon atoms having 3 or more carbon atoms are represented by the following formula (II): Mono (meth) acrylate (II
The present invention provides an optical transmission fiber comprising, as a sheath component, a resin composition of (I) and a polyfunctional monomer (IV) containing two (meth) acryloyl groups in a molecule and having a fluorine atom content of 30% by weight or more.

The fluorinated (meth) acrylate (A), which is a constituent monomer of the fluorinated copolymer, and the fluorinated (meth) acrylate (II) used in the resin composition of the present invention in monomer form A fluorinated aliphatic group R is a perfluoroalkyl group or a partially fluorinated aliphatic group, which is linear, branched, or has a main chain in which an oxygen atom intervenes;
For example

[0022]

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Any of these may be used. Specific examples of the fluorinated (meth) acrylates (A) and (II) include the following compounds.

[0024]

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[0025]

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[0026]

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[0027]

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The fluorinated (meth) acrylates (A) and (II) may each be a mixture of two or more compounds having different structures. The fluorinated (meth) acrylates (A) and (II) may be the same or different. Note that, needless to say, the present invention is not limited by the above specific examples.

In the fluorine-containing copolymer (I) according to the present invention, one or more mono (meth) acrylates (B) having an ester substituent having 3 or more carbon atoms are substituted.
Is to improve the transparency of the fluorinated copolymer (I), the fluorinated (meth) acrylate (II), the mono (meth) acrylate (III), and two or more (meth) acryloyl groups in the molecule. Improvement of compatibility with the contained polyfunctional monomer (IV), improvement of adhesion to a quartz core wire or plastic core wire, and a cured resin obtained by irradiating the resin composition according to the present invention with active energy rays, that is, a sheath. It is extremely important for improving the transparency and flexibility of the material.

When the number of carbon atoms in the ester substituent of the mono (meth) acrylate (B) is less than 3, or when the mono (meth) acrylate
When the acrylate (B) is missing, the transparency, compatibility, adhesion, and transparency of the cured resin of the fluorinated copolymer (I) become poor. The proportion of the mono (meth) acrylate (B) in the fluorinated copolymer (I) is as follows:
It is 0.5 to 50% by weight, and 2 to 30% by weight is particularly preferred.

Specific examples of the mono (meth) acrylate (B) include n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t- -Butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and isostearyl (meth) acrylate Such as aliphatic ester (meth) acrylate, glycerol (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxy (meth) acrylate, glycidyl (meth) acrylate,
Allyl (meth) acrylate, butoxyethyl (meth)
Acrylate, butoxyethylene glycol (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, γ-methacryloxypropyltrimethoxysilane,
2-methoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, nonylphenoxypolypropylene glycol (meth) acrylate, Aronix M-5700 (Toa Gosei) Phenoxyethyl (meth) acrylate, phenoxypropylene glycol (meth) acrylate,
Phenoxydipropylene glycol (meth) acrylate, phenoxypolypropylene glycol (meth) acrylate, and AR-206, MR-260, AR-
200, AR-204, AR-208, MR-200,
Phosphate ester group-containing (meth) acrylates such as MR-204 and MR-208 (all manufactured by Daihachi Chemical Co., Ltd.), and Biscoat 2000 and Biscoat 2308 (all manufactured by Osaka Organic Co., Ltd.), polybutadiene (meth) acrylate
Polyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, polyethylene glycol-polybutylene glycol (meth) acrylate, polystyrylethyl (meth) acrylate, Light ester HOA-MS, light ester HOMS (manufactured by Kyoeisha Yushi), benzyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, isobornyl (meth) acrylate, methoxylated cyclodecatriene (meta) ) Acrylate, phenyl (meth) acrylate, and FA-512A and FA-5 manufactured by Hitachi Chemical
12M and the like. It is needless to say that the present invention is not limited by these specific examples.

Among the specific examples of the above-mentioned mono (meth) acrylate (B), those which improve the transparency and compatibility of the fluorinated copolymer and the transparency of the cured resin by introducing a small amount thereof include an ester moiety. Benzyl (meth) acrylate (b-1), cyclohexyl (meth) acrylate (b-2), dicyclopentanyl (meth) acrylate (b-3), dicyclopentenyl (meth), wherein the substituent has a cyclic structure Acrylate (b-4), isobornyl (meth) acrylate (b-5), methoxylated cyclodecalin (meth) acrylate (b-6), phenyl (meth)
Acrylate (b-7) and FA-5 manufactured by Hitachi Chemical
12A (b-8) and FA-512M (b-9) are preferred.

Among them, dicyclopentenyl (meth) acrylate (b-4) and isobornyl (meth) acrylate (b-5) are used to improve the adhesion of the optical transmission fiber to the quartz core wire and plastic core wire. Is particularly preferred.

Further, from the viewpoint of the temperature stability with respect to the transparency of the cured resin, that is, the transparency of the sheath portion of the optical transmission fiber, dicyclopentenyl (meth) acrylate (b-
4) and isobornyl (meth) acrylate (b-5)
Is preferably simultaneously contained as a component in the fluorinated copolymer (I).

The molecular weight of the fluorinated copolymer (I) is not particularly limited. However, it is preferable that the molecular weight of the fluorinated copolymer (I) be such that the resin composition according to the present invention has such a viscosity that it can be applied to the optical transmission fiber core. The average molecular weight Mn is preferably 1,000 or more.

The fluorinated copolymer (I) is indispensable for imparting the resin composition according to the present invention with such a viscosity that it can be applied to the core fiber of the optical transmission fiber. Lack of I) makes application extremely difficult,
Optical transmission fibers are also poor.

In the resin composition according to the present invention, one or two or more mono (meth) acrylates (III) having an ester substituent having 3 or more carbon atoms can be used to improve the transparency of the cured resin, This is essential from the viewpoint of adhesion to the transmission fiber core. In addition, when the number of carbon atoms of the ester substituent of the mono (meth) acrylate (III) is less than 3, or when the mono (meth) acrylate (III) is missing, the transparency and adhesion of the resin after curing are reduced. Is poor.

Specific examples of the mono (meth) acrylate (III) include the same compounds as the specific examples of the mono (meth) acrylate (B). It is needless to say that the present invention is not limited by these specific examples.

Among the specific examples of the mono (meth) acrylate (III), the substituent at the ester moiety has a cyclic structure as one which can effectively improve the transparency and adhesion of the cured resin by adding a small amount thereof. , The aforementioned b-1, b-2,
b-3, b-4, b-5, b-6, b-7, b-8 and b-9 are preferred.

Among them, dicyclopentenyl (meth) acrylate (b-4) and isobornyl (meth) acrylate (b) are used to effectively improve the adhesion of the optical transmission fiber to the quartz core wire and the plastic core wire. -5) is particularly preferred.

Furthermore, from the viewpoint of temperature stability concerning the transparency of the cured resin, dicyclopentenyl (meth)
It is preferable that the acrylate (b-4) and the isobornyl (meth) acrylate (b-5) are simultaneously contained in the resin composition according to the present invention.

The polyfunctional monomer (IV) containing two or more (meth) acryloyl groups in the molecule is one in which two or more (meth) acrylic acids are linked to a dihydric or higher polyhydric alcohol by an ester bond. Flexibility to the cured resin,
It is indispensable for the resin composition according to the present invention to impart mechanical toughness and the like.

Specific compounds include, for example, the following compounds. c-1 ethylene glycol di (meth) acrylate c-2 diethylene glycol di (meth) acrylate c-3 triethylene glycol di (meth) acrylate c-4 polyethylene glycol di (meth) acrylate (number average molecular weight 150 to 1000) c- 5 Propylene glycol di (meth) acrylate c-6 Dipropylene glycol di (meth) acrylate c-7 Tripropylene glycol di (meth) acrylate c-8 Polypropylene glycol di (meth) acrylate (number average molecular weight 200 to 1000) c- 9 neopentyl glycol di (meth) acrylate c-10 1,3-butanediol di (meth) acrylate c-11 1,4-butanediol di (meth) acrylate c-12 1,6-hexanediol di ( Data) acrylate c-13 hydroxypivalic acid ester neopentyl glycol di (meth) acrylate

[0044]

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C-16 Bisphenol A di (meth)
Acrylate c-17 Trimethylolpropane tri (meth) acrylate c-18 Pentaerythritol tri (meth) acrylate c-19 Dipentaerythritol hexa (meth) acrylate c-20 Pentaerythritol tetra (meth) acrylate c-21 Trimethylolpropanedi (Meth) acrylate c-22 dipentaerythritol monohydroxypenta (meth) acrylate Other specific examples include Neomer NA-305 (c
-23), Neomer BA-601 (c-24), Neomer TA-505 (c-25), Neomer TA-401
(C-26), Neomer PHA405X (c-27),
Neomer TA705X (c-28), Neomer EA40
0X (c-29), Neomer EE401X (c-3
0), Neomer EP405X (c-31), Neomer H
B601X (c-32), Neomer HB605X (c-
33) [Made by Sanyo Chemical Industries, Ltd.], KAYARAD
HY-220 (c-34), HX-620 (c-3
5), D-310 (c-36), D-320 (c-3)
7), D-330 (c-38), DPHA (c-3)
9), DPCA-20 (c-40), DPCA-30
(C-41), DPCA-60 (c-42), DPCA
-120 (c-43) [all manufactured by Nippon Kayaku Co., Ltd.] and the like.

According to the findings of the present inventors, from the viewpoint of transparency of the cured resin, among the above specific examples, the polyfunctional monomer (IV) containing two or more (meth) acryloyl groups is , Those containing a methyl group in the molecule are preferred,
c-5, c-6, c-7, c-8, c-9, c-13,
c-14, c-15, c-17, c-21, c-23,
c-25 and the like are particularly preferred. In addition, polyfunctional monomers (I
As V), a single compound may be used, or two or more compounds having different structures may be used. Note that, needless to say, the present invention is not limited by the above specific examples.

In the resin composition of the present invention, a fluorinated copolymer (I), a fluorinated (meth) acrylate (II),
The composition ratio of the mono (meth) acrylate (III) and the polyfunctional monomer (IV) can be arbitrarily selected according to the desired viscosity and refractive index. (III): (IV) = 1: 1000 to 95: 5, (II): [(III) + (IV)] = 50:50 to 100
0: 1, (I): [(II) + (III) + (IV)] = 1:99 to 10
000: 1 is preferred.

The fluorinated copolymer (I) according to the present invention comprises
It is produced by a polymerization method known in the art, for example, a method such as radical polymerization or anion polymerization, using heat, light, an electron beam, or radiation as a polymerization initiation energy.
Alternatively, radical polymerization using light as a polymerization initiation energy is preferable. As a polymerization form by these polymerization methods, both bulk polymerization and solution polymerization can be adopted. In the case of using heat as the polymerization initiation energy, a catalyst-free or a polymerization initiator such as azobisbutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide-cobalt naphthenate, Known so-called photopolymerization initiators (for example, VI-1 to VI
11) and, if necessary, a photosensitizer such as an amine compound or a phosphorus compound, whereby the polymerization can be further accelerated.

In these radical polymerizations, lauryl mercaptan, octyl thioglycolate, γ-mercaptopropyltrimethoxysilane,
By using a mercapto group-containing chain transfer agent such as C ₁₈ F ₁₇ CH ₂ CH ₂ SH in combination, the degree of polymerization of the fluorinated copolymer (I) can be adjusted. When polymerization is performed by electron beam or radiation, addition of a polymerization initiator or the like is not particularly required.

When the fluorinated copolymer (I) is obtained by solution polymerization, the solvent is not limited as long as it does not adversely affect the polymerization reaction. In the resin composition according to the present invention, the fluorinated (meth) acrylate (A) and the mono (meth) acrylate (B), which are constituent monomers of the fluorinated copolymer (I), are each fluorinated (meth) When equal to the acrylate (II) and the mono (meth) acrylate (III), the polymerization of the fluorine-containing copolymer (I) is carried out by reacting the unreacted fluorine-containing (meth) acrylate (A) and the mono (meth) acrylate ( The resin composition of the present invention can be obtained by stopping at the stage where B) remains and then adding and mixing a predetermined amount of the polyfunctional monomer (IV).

The resin composition of the present invention comprises a fluorine-containing copolymer (I), a fluorine-containing (meth) acrylate (II),
In addition to the essential components of the mono (meth) acrylate (III) and the polyfunctional monomer (IV), various additives (V) and a photopolymerization initiator (VI) can be contained as necessary.

As the additive (V), a solvent for adjusting viscosity, a light stabilizer, a coloring agent, a coupling agent for improving the adhesion to the optical transmission fiber core, and a coating agent for uniformly coating the core are used. Examples include an antifoaming agent, a leveling agent, a surfactant, and a surface modifier for controlling the adhesion between the optical transmission fiber and the primary coating agent.

Examples of the coupling agent include silane-based, titanium-based, and zircoaluminate-based ones. Of these, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, dimethylvinylmethoxysilane, phenyltrimethoxysilane Silane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ
-Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropylmethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-acryloxypropylmethyltrimethoxysilane, γ-acryloxy Silanes such as propylmethyldimethoxysilane are particularly preferred.

The antifoaming agent, leveling agent and surfactant are preferably fluorine-based. When the active energy ray-curable resin composition according to the present invention is used for the purpose of reducing the refractive index, improving the transparency, and plasticizing the resin obtained by curing, the additive (V) Other than the above, a non-polymerizable fluorine compound such as HO- (C
_{H 2) r -C s F 2s} + 1 (r is an integer from 1 to 4, s is 1
Is an integer of up to 20. HO)
_{OC- (CH 2) t -C u} F 2u + 1 (t is an integer of 0 or 1 to 4, u is an integer from 1 to 20.) Such as fluorinated carboxylic acids, referred colloquially fluorine oil Fluorinated polyethers used, and compounds commonly called fluorinated inert liquids such as N (C ₄ F ₉ ) ₃ , perfluorodecalin, C ₈ F ₁₇ OC ₄ F ₉ and C ₉ F ₂₀ can be used. . The proportion of this non-polymerizable fluorine compound additive in the active energy ray-curable resin composition is preferably 30% by weight or less, and more preferably 20% by weight or less because the strength of the cured resin is reduced if added excessively. More preferred.

The optical transmission fiber according to the present invention is obtained by applying or impregnating the active energy ray-curable resin composition to the core of the optical transmission fiber, and then irradiating the active energy ray such as light, electron beam, or radiation. By polymerizing and curing to form a sheath. In some cases, heat can also be used as energy rays.

When light such as ultraviolet light is used as the active energy source, a photopolymerization initiator (IV) known in the art, for example, IV-1: benzophenone, IV-2: acetophenone, IV-3: benzoin, IV -4: benzoin ethyl ether, IV-5: benzoin isobutyl ether, IV-
6: benzyl methyl ketal, IV-7: azobisisobutyronitrile, IV-8: 1-hydroxycyclohexyl phenyl ketone, IV-9: 2-hydroxy-2-methyl-1-phenyl-1-one, IV- 10: 1- (4'-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, IV-11: 1- (4'-dodecyl-
Phenyl) -2-hydroxy-2-methylpropane-1
It is preferable to use -one or the like as a catalyst.

Further, if necessary, a photosensitizer such as an amine compound or a phosphorus compound may be added to further accelerate the polymerization. The preferred ratio of the photopolymerization initiator in the active energy ray-curable resin composition according to the present invention is 0.1%.
It is from 0.1 to 10% by weight, more preferably from 0.1 to 7% by weight.

In the case of polymerizing and curing with an electron beam or radiation, addition of a polymerization initiator or the like is not particularly required. As described above, the solvent can be blended to control the viscosity, coatability, and film thickness of the resin composition of the present invention. Such a solvent is not particularly limited as long as it does not adversely affect the polymerization reactivity of the composition of the present invention. However, alcohols such as methanol, ethanol and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, Methyl acetate, ethyl acetate, ester systems such as butyl acetate, chloroform, dichloroethane, chlorine systems such as carbon tetrachloride, and benzotrifluoride, chlorobenzotrifluoride, m-xylene hexafluoride, tetrachlorodifluoroethane, 1,1,2-trichloro-
Low boiling point solvents such as 1,2,2-trifluoroethane and trichloromonofluoromethane are preferred from the viewpoint of workability.

When the active energy ray-curable resin composition of the present invention is applied or impregnated on a core fiber of an optical fiber as a solution dissolved in a solvent, it may be heated at room temperature or, if necessary, before starting the polymerization curing. A step of removing the solvent under reduced pressure is required. When the solvent is removed by heating, it is preferable to carry out the heating at a temperature of 80 ° C. or lower so as not to cause the polymerization of the monomer or the like by heating.

As a method for applying the energy ray-curable resin composition according to the present invention to a substrate, various methods known in the art, for example, by brushing, an applicator, a bar coater, a roller brush, a roll coater, etc. A coating method, a spray coating method using an air spray or airless spray coating machine, a flow coating method (flow coating) using a shower coater or a curtain flow coater, a dipping method, a casting method, a spinner coating method, and the like can be used. It is desirable to properly use them according to the material of the optical transmission fiber core wire and the like.

When the resin composition of the present invention is applied to the core of the optical transmission fiber of the present invention and cured, the core of the optical transmission fiber is immersed continuously in a storage tank containing the resin composition and pulled up. In accordance with the method of removing the solvent, irradiating the active energy ray to cure the sheath portion, or continuously applying the resin composition through a core of an optical transmission fiber to a base capable of continuously supplying the resin composition, and optionally removing the solvent. After removing, a method of irradiating active energy rays to cure the sheath portion, etc., such as DT2,459,320, JP-A-53-1395
For example, a method known in the art such as that described in No. 45 can be used.

When the sheath portion of the optical transmission fiber of the present invention is polymerized and cured, a germicidal lamp, a fluorescent lamp for ultraviolet rays, a carbon arc, a xenon lamp, a high-pressure mercury lamp for copying, a medium or high-pressure mercury lamp, an ultra-high pressure, known in the art. In the case of ultraviolet curing of a coating layer having a thickness of 5 μm or less, a mercury lamp, an electrodeless lamp, a metal halide lamp, ultraviolet light using natural light as a light source, or an electron beam using a scanning type or curtain type electron beam accelerating path can be used. Irradiation is preferably performed in an atmosphere of an inert gas such as nitrogen gas from the viewpoint of increasing the efficiency of polymerization.

Examples of the core fiber of the optical transmission fiber in the present invention include quartz and plastics such as polymethyl methacrylate, deuterated polymethyl methacrylate, polyethyl methacrylate, polystyrene and polycarbonate.

In the formation of the sheath component of the optical transmission fiber, when a conventional thermosetting silicone resin or a hot melt of a fluorinated polymer is used as described above, the light transmission fiber is shrunk due to shrinkage of the sheath component after curing. The disadvantage is that microbending occurs in the fiber, resulting in significant transmission loss. However, if the resin composition according to the present invention is used, there is no such a problem as described above, and therefore, there is an economical advantage such as improvement in quality and yield of the optical transmission fiber.

Further, the optical transmission fiber of the present invention is remarkably excellent in the adhesion between the core portion and the sheath portion as compared with the conventional one, so that it can withstand the use conditions accompanied by severe vibration and bending. There is an advantage.

Further, by using the resin composition according to the present invention, the drawing speed of the optical transmission fiber becomes 3 to 6 m / sec, and the production speed of the optical transmission fiber becomes 3 to 5 times the conventional one. There is.

In the optical transmission fiber of the present invention, a transparent resin having a refractive index of about 1.33 can be obtained by adjusting the ratio of each component of the resin composition of the present invention. Large diameter is possible.

[0068]

Next, a preferred embodiment of the present invention will be described. Is first allowed to react with _{CH 2 = CHCOOCH 2 CH 2 C} 8 F 17 fluorinated (meth) acrylate and isobornyl such (meth) acrylate and / or dicyclopentenyl (meth) acrylate in the presence of a photopolymerization initiator A fluorinated copolymer is obtained.

The fluorinated copolymer (I) has CH ₂ ＣＨCH
Fluorine-containing (meth) acrylates (II) such as COOCH ₂ CH ₂ C ₈ F ₁₇ , isobornyl (meth) acrylate and / or dicyclopentenyl (meth) acrylate (II)
I), a resin composition is produced by mixing with a polyfunctional monomer (IV) such as propylene glycol di (meth) acrylate containing a methyl group in the molecule.

The mixing ratio in this case is (III) :( IV)
Is 1: 1000 to 95: 5, and (II): [(III)
+ (IV)] is 50:50 to 1000: 1,
(I): [(II) + (III) + (IV)] is 1:99 to 10
000: 1. The photopolymerization initiator is added in an amount of 0.1 to 7% by weight in the resin composition.

In addition, a chain transfer agent, a light stabilizer, a colorant, a coupling agent, an antifoaming agent, a leveling agent, a surfactant and the like can be appropriately blended into the resin composition. A solution obtained by dissolving this resin composition in a solvent is coated or impregnated on an optical fiber core such as quartz, heated to room temperature or 80 ° C. or lower, desolvated by decompression, irradiated with active energy rays, and cured to a sheath component. Thus, an optical transmission fiber can be obtained.

[0072]

EXAMPLES Next, specific synthesis examples and examples of the present invention will be described. However, it is needless to say that the present invention is not limited by the description. "Part" in the sentence,
“%” Is based on weight.

The performance of the cured resin obtained by irradiation with active energy rays was evaluated by the following method. Evaluation of adhesion Polymethyl methacrylate plate [Acrylite (trade name) -L- # 001, plate thickness 2 mm, manufactured by Mitsubishi Rayon Co., Ltd.], polystyrene plate [Stylon (trade name, Dow Chemical Company)
The active energy ray-curable resin according to the present invention was applied to a [plate thickness of 2 mm] and a glass plate (plate thickness of 5 mm) so that the cured film thickness became 100 μm.

As the active energy ray source, a high-pressure mercury lamp 160 W / cm 2 lamp condensing type was used, and the conveyor speed was 2
Cured at 00 m / min. In the case of the comparative hot-melt type fluorine-containing resin, a film having a thickness of 100 μm was obtained from a hot press at a pressure of 100 kg / cm ² at 200 ° C. for 5 minutes, and this was overlaid on each base material surface. 5kg / cm ²
Under pressure and laminated.

The adhesion test of the sample thus obtained was evaluated according to JIS 5400 evaluation criteria.

[0076]

[Table 1]

Evaluation of optical transmission performance The optical transmission performance of the optical transmission fiber is the same as that of the apparatus shown in FIG.
/ Km) was measured and evaluated. The measurement conditions are as follows.

Interference filter (main wavelength) 650 μm Total length of optical transmission fiber 5 m Cutting length of optical transmission fiber 4 m Diameter of bobbin 190 mm Mandrel test In order to evaluate the adhesion and toughness of the sheath material to the optical transmission fiber core, a diameter of 5 mm was used. An optical transmission fiber was wound around a mandrel, and it was enlarged under a microscope. The adhesion between the optical transmission fiber core wire and the sheath material and the presence or absence of cracks in the sheath material were observed, and evaluated in the following three grades.

Evaluation point 3: No change in adhesion between the core portion and the sheath portion, and no occurrence of cracks or the like in the sheath portion was observed. 2: A change in adhesion between the core portion and the sheath portion and / or a slight occurrence of cracks or the like in the sheath portion is recognized.

1: Peeling between the core portion and the sheath portion and / or occurrence of cracks in the sheath portion are observed. Hereinafter, all the abbreviations of the compounds indicate the aforementioned compounds. A after the abbreviation indicates that it is an acrylate compound and M is a methacrylate compound.

Synthesis Example 1 a-1 / b-5 (A) / b-4 (A) = 90/8/2
(%) Synthesis of copolymer a-1 was placed in a 500 ml four-necked round bottom flask equipped with a cooling condenser, a thermometer and a stirrer.
180 g, 18 g of b-5 (A), 2 g of b-4 (A) and 1 g of azobisisobutyronitrile (hereinafter referred to as AIBN) are weighed, and are weighed at 70 ° C. in an N ₂ gas atmosphere at 150 ° C. for 15 minutes.
Stirred for minutes. The hot viscous bulk polymer was taken out of the system.

The molecular weight determined by GPC was 460,000 in terms of styrene. Under an atmosphere at 25 ° C., the polymer was transparent and had a refractive index nD ²⁵ of 1.370. Synthesis Examples 2 to 14 Hereinafter, the molecular weight and the refractive index of the fluoropolymer synthesized in the same manner as in Synthesis Example 1 are collectively shown in Tables 2 and 3.

[0083]

[Table 2]

[0084]

[Table 3]

*) Appearance A: transparent B: slightly turbid

C: There is considerable turbidity. D: Opaque Synthesis Example 15 a-1 / b-5 (A) / n-butyl acrylate = 90
Synthesis of / 5/5 (%) copolymer 500 m equipped with cooling condenser, thermometer and stirrer
l in a four-necked round bottom flask, 90 g of a-1 and b-5
(A) 5 g, n-butyl acrylate 5 g, octyl thioglycolate 0.5 g, AIBN 0.3 g and 1,
230 g of 1,1-trichloroethane was weighed out and reacted at 80 ° C. for 10 hours in an N ₂ gas atmosphere. The solvent was distilled off under reduced pressure to obtain the desired transparent polymer. Mn = 120,000,
nD ²⁵ = 1.373.

Synthesis Examples 16 to 18 The molecular weight and the refractive index of the fluoropolymer synthesized in the same manner as in Synthesis Example 15 are summarized in Table 4.

[0088]

[Table 4]

Note: Evaluation criteria for appearance are the same as those in Table 1. Synthesis Example 19 Synthesis of a-1 / b-3 (M) = 93/7 (%) Copolymer In a 500 ml glass cylindrical flask equipped with a stirrer,
372 g of a-1 and 28 g of b-3 (M) and 0.72 g of IV-9 as a photopolymerization initiator were weighed out, and irradiated with a high-pressure mercury lamp 80 W / cm1 from the side while stirring at 60 ° C. for 16 seconds. Reacted. By this operation, at 50 ° C., 100
A viscous polymer of 00 cps was obtained. The polymer was transparent in an atmosphere at 25 ° C., the molecular weight Mn by GPC was 36,000, and the refractive index nD ²⁵ was 1.365. Further, the remaining unreacted monomer by gas chromatography was 17% of the total amount.

Synthesis Examples 20 to 28 Table 5 summarizes the viscosities, unreacted monomer residual ratios, and the like of the fluorine-containing copolymer synthesized in the same manner as in Synthesis Example 19.

[0091]

[Table 5]

Production Examples 1 to 15 and Comparative Production Examples 1 to 10
(Production of active energy ray-curable resin composition) The fluorinated copolymer (I), fluorinated (meth) acrylate (II), mono (meth) acrylate (III), Functional monomer (I
V), an additive (V) and a photopolymerization initiator (VI) were used to prepare an active energy ray-curable resin composition.

Examples 1 to 15 and Comparative Examples 1 to 10 The adhesion of this resin composition to a polymethyl methacrylate plate, a polystyrene plate, and a glass plate, and various characteristics when used as a sheath material of an optical transmission fiber are shown. 6, Table 7, Table 8, Table 9, Table 10, Table 11 and Table 12 are shown together.

When the active energy ray-curable resin composition was used, the core of the optical transmission fiber was immersed continuously in a bath of the resin composition and pulled up, and at a drawing speed of 300 m / min, 160 W / cm. Ultraviolet light was irradiated by three high-pressure mercury lamp condensing lamps to form an optical transmission fiber.

The optical transmission fiber shown in the comparative example was formed by applying a fluorinated polymer melted at the temperature shown in the table to the optical transmission fiber core wire and air cooling. The curing of the silicone resin shown in the comparative example was performed at 150 ° C., 1
Minutes. In this case, the drawing speed of the optical transmission fiber is 3 m / min.

In an optical transmission fiber having polymethyl methacrylate and polystyrene as core components, the diameter of the core wire is 5 mm.
The thickness of the sheath portion was set to 40 μm. In an optical transmission fiber having quartz as a core component, the core wire has a diameter of 250 mm.
μm, and the thickness of the sheath portion was 30 μm.

In the table, RM and PS indicate optical transmission fibers having polymethyl methacrylate and polystyrene as cores, respectively, and G indicates an optical transmission fiber having quartz as a core.

[0098]

[Table 6]

[0099]

[Table 7]

[0100]

[Table 8] *) Fluorinated surfactant from Dainippon Ink and Chemicals, Inc.

[0101]

[Table 9]

[0102]

[Table 10]

[0103]

[Table 11]

[0104]

[Table 12]

[0105]

As is clear from Tables 6 to 12, the optical transmission fiber using the active energy ray-curable resin according to the present invention for the sheath material has a much higher optical transmission property than the conventional one. .

Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08L 33/16 LHV C08L 33/16 LHV

Claims (3)

(57) [Claims] (1) The following general formula: (Wherein, Rf is a fluorinated aliphatic group having 1 to 20 carbon atoms, n is 0 or an integer of 1 to 6, and R is H, CH ₃
Or F. ) And a mono (meth) acrylate (B) having one or more kinds of mono (meth) acrylates having an ester substituent having 3 or more carbon atoms (B). Combined (I), the following general formula: (In the formula, Rf, n and R are the same as described above.) Fluorine-containing (meth) acrylate (II) represented by the formula (1), one or more mono (meth) acrylates having an ester substituent having 3 or more carbon atoms ( Optical transmission fiber comprising, as a sheath component, a resin composition containing meth) acrylate (III) and a polyfunctional monomer (IV) having two (meth) acryloyl groups in the molecule and having a fluorine atom content of 30% by weight or more. . 2. A resin composition containing isobornyl (meth) acrylate as one or more mono (meth) acrylates (B) and / or (III) having an ester substituent having 3 or more carbon atoms. The optical transmission fiber according to claim 1, wherein an object is used. 3. Mono- (meth) acrylate (B) and / or (III) having one or two or more ester substituents having 3 or more carbon atoms, containing dicyclopentenyl (meth) acrylate. The optical transmission fiber according to claim 1, wherein a resin composition is used.