JPH08310841A - Coated optical fiber and its production - Google Patents

Abstract

PURPOSE: To increase the cure rate of a resin and consequently to increase the fiber drawing speed by coating an optical fiber with a UV-curing resin through a photopolymerization initiator such as bisacylphosphine oxide. CONSTITUTION: An optical fiber preform 41 is introduced into a wire drawing furnace 42, heated, melted and drawn into a glass optical fiber 1, the optical fiber is sent to a resin coating device 43a and coated with a UV-curing resin through a photopolymrization initiator such as bisacylphosphine oxides and then irradiated with UV in a UV irradiation device 44a to cure the coating layer, and a resin-coated optical fiber 48 is formed. The resin-coated optical fiber is pulled and taken up on a winder 49.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated optical fiber using an ultraviolet curable resin mixture and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, optical fibers used for optical communication are not limited to optical glass fibers and silica glass fibers, and it is said that it is desirable to apply a plastic coating to the outer periphery of each of the optical fibers immediately after they are made into fibers.

This is said to prevent the strength of the fiber from deteriorating due to scratches on the surface of the fiber caused by forming the fiber or growth of cracks due to exposure to air in the bare fiber state.

As a plastic layer used for this purpose, a thermosetting silicone resin or an ultraviolet curable resin is generally used. In recent years, from the viewpoint of workability, the technique of coating with the ultraviolet curable resin is particularly used. The importance of is increasing.

The mixture for obtaining the UV-curable resin has a basic composition of acrylic oligomer, reactive diluent,
And a photopolymerization initiator.

[0006]

Photopolymerization initiation which greatly affects the curing rate depending on the type of photopolymerization initiator, and therefore enhances the curing rate of this resin in the coating process and consequently the production line speed. The choice of agent is important.

Therefore, development of a coating layer coating method using a photopolymerization initiator having an extremely high curing rate is important for speeding up the manufacturing process and improving quality.

Further, in the conventional production of an optical fiber having a multilayer coating structure, the photopolymerization initiator for forming the outer layer absorbs light energy, and the photopolymerization initiator for forming the inner layer works sufficiently. There was a problem that I couldn't.

For this reason, a plurality of coating steps may be provided, which causes problems in workability and economy.

In order to solve the above problems, the inventors of the present invention have diligently studied, and by using a bisacylphosphine oxide-based photopolymerization initiator as an essential component of the ultraviolet curable resin mixture, the curing rate can be improved. The inventors have found that a great improvement is possible, and have completed the present invention.

[0011]

The present invention provides a coated optical fiber using a mixture containing a bisacylphosphine oxide-based photopolymerization initiator as an essential component of an ultraviolet curable resin mixture, as a coating material for an optical fiber. It is a thing.

Further, the present invention provides a method for producing a coated optical fiber, which uses a mixture containing a bisacylphosphine oxide-based photopolymerization initiator as an essential component of an ultraviolet curable resin mixture, as a coating material for an optical fiber. is there.

More specifically, the present invention will be described in more detail below.

The present invention relates to an optical fiber coated with an ultraviolet curable resin, wherein the resin contains at least a photopolymerization initiator of bisacylphosphine oxides.

The present invention further provides at least a coating resin,
The present invention relates to an optical fiber comprising an acrylate oligomer, a reactive diluent, and at least a photopolymerization initiator of bisacylphosphine oxides.

Further, the present invention is characterized by containing at least a polyol, an isocyanate and an acrylate as the acrylate oligomer.

Furthermore, the present invention is characterized in that the polyol is polyoxytetramethylene glycol.

Further, the present invention is characterized in that the isocyanate is tolylene diisocyanate.

Further, the present invention is characterized in that the acrylate is 2-hydroxyethyl acrylate.

The present invention is also characterized in that it contains at least 2-ethylhexyl acrylate or trimethylolpropane triacrylate as the reactive diluent.

Further, in the present invention, the photopolymerization initiator is represented by the following formula:

[0022]

Embedded image

(Here, when R'is a 2,4,4-trimethylpentyl group, R is further a 2,6-dimethoxyphenyl group, 2,6-dichlorophenyl group, 2,4,6.
-Trichlorophenyl group, 2,4,6-trimethoxyphenyl group, 2,6-dimethylphenyl group, 2,4,6-trimethylphenyl group, phenyl group, methyl group; R'is phenyl If it is a group, then R
Represents a methyl group or a phenyl group; when R ′ is a 4-methylphenyl group, then R is a methyl group, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl group,
2,4,6-trichlorophenyl group, 2,4,6-trimethoxyphenyl group, 2,6-dimethylphenyl group,
Represents a group selected from a 2,4,6-trimethylphenyl group; when R'is a methyl group, R represents a methyl group; R '
Is an ethyl group, R represents a methyl group; and R'is a propyl group, R represents a methyl group).

Further, the present invention further comprises at least benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one as a photopolymerization initiator. -Hydroxy-2-methyl-1-phenyl-pyropan-1-one.

Further, the present invention is characterized in that, of the coating layers of the optical fiber coated with a plurality of coating layers, at least one coating resin contains at least a photopolymerization initiator of bisacylphosphine oxides. The present invention relates to a manufacturing method of.

In the present invention, at least one layer coating resin of the coating layers of the optical fiber coated with a plurality of coating layers is
The present invention relates to a method for producing an optical fiber, which comprises an acrylate oligomer, a reactive diluent and at least a photopolymerization initiator of bisacylphosphine oxides.

The present invention also provides a coated optical fiber having a coating layer of an inner layer and an outer layer, wherein the inner coating layer is formed by using bisacylphosphine oxides as a photopolymerization initiator. It is about fiber.

Furthermore, the present invention is a method for producing a coated optical fiber having a coating layer of an inner layer and an outer layer, characterized in that the inner coating layer is formed using a bisacylphosphine oxide as a photopolymerization initiator. The present invention relates to a coated optical fiber manufacturing method.

The present invention also relates to a method for producing an optical fiber, wherein the coating layers of the inner layer and the outer layer are simultaneously cured by irradiation with ultraviolet rays.

The present invention further relates to a coated optical fiber characterized in that the bisacylphosphine oxides as a photopolymerization initiator is contained in an amount of 0.1 to 10 parts by weight.

The present invention also relates to a method for producing an optical fiber, wherein the bisacylphosphine oxides as the photopolymerization initiator is 0.1 to 10 parts by weight.

The present invention will be described in more detail below.

(Acrylic Oligomer) The acrylic oligomer (or (meth) acrylic oligomer) according to the present invention
The essential components of the polyol component, isocyanate component,
And an acrylate component. Although various components described below can be used, the preferable molecular weight of the oligomer is 1,000 to 100,000.

In the present invention, the polyol component is not particularly limited, but examples of suitable polyol components include, for example, polyether polyols such as polyoxytetramethylene glycol, polypropylene glycol, polyethylene glycol, or polyolefin glycol, polyester polyol, polycarbonate. Examples thereof include polyols and polycaprolactone polyols.

In the present invention, the isocyanate component is not particularly limited, but as the isocyanate component which can be preferably used, tolylene diisocyanate, diphenylmethane diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, etc. Is.

In the present invention, the acrylate component is not particularly limited, but the acrylate component that can be preferably used is a hydroxyalkyl group such as 2-hydroxyethyl (meth) acrylate or 2-hydroxypropyl (meth) acrylate. It has about 2 to 4 carbon atoms.

(Reactive Diluent) The reactive diluent that can be used in the present invention is not particularly limited, but a reactive diluent that can be preferably used is 2-ethylhexyl acrylate tetrahydrofurfuryl alcohol caprolactone adduct ( (Meth) acrylate, nonylphenol ethylenoxide adduct (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bisphenol diethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, penta Erythritol tri (meth) acrylate, mono- or poly (meth) acrylates such as epoxy (meth) acrylate synthesized from bisphenol diglycidyl ether,
Acrylic esters such as diallyl adipate, diallyl phthalate, triallyl trimellitate and triallyl isocyanurate, styrene, vinyl acetate, N-vinylpyrrolidone, N, N'-dimethylacrylamide,
N, N'-dimethylaminopropyl acrylamide,
A vinyl compound such as N, N′-dimethylaminoethyl acrylate.

(Photopolymerization Initiator) One of the photopolymerization initiators that can be preferably used in the present invention is a bisacylphosphine oxide type (JP-A-5-345790), which is a photopolymerization initiator having good curability. There is no particular limitation on the molecular structure as long as it is an agent, but especially the following formula,

[0039]

Embedded image

(Here, when R'is a 2,4,4-trimethylpentyl group, R is further a 2,6-dimethoxyphenyl group, 2,6-dichlorophenyl group, 2,4,6.
-Trichlorophenyl group, 2,4,6-trimethoxyphenyl group, 2,6-dimethylphenyl group, 2,4,6-trimethylphenyl group, phenyl group, methyl group; R'is phenyl If it is a group, then R
Represents a methyl group or a phenyl group; when R ′ is a 4-methylphenyl group, then R is a methyl group, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl group,
2,4,6-trichlorophenyl group, 2,4,6-trimethoxyphenyl group, 2,6-dimethylphenyl group,
Represents a group selected from a 2,4,6-trimethylphenyl group; when R'is a methyl group, R represents a methyl group; R '
Is an ethyl group, R represents a methyl group; and R ′ is a propyl group, R represents a methyl group).

Further, in the present invention, as a photopolymerization initiator, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one,
2-Hydroxy-2-methyl-1-phenyl-pyropan-1-one can be preferably used.

It is also possible to use a mixture of two or more of these photopolymerization initiators, or to use in combination with a small amount of sensitization aid such as amines.

The amount of the photopolymerization initiator added to the mixture according to the present invention is preferably 0.1 part by weight or more and 10 parts by weight or less.

That is, if it is 0.1 or less, it is difficult to obtain a sufficient curing rate, and if it is 10 parts or more, problems such as precipitation of a photopolymerization initiator may occur.

(Preparation Method of UV-Curable Resin Mixture) The UV-curable resin of the present invention contains the above-mentioned acrylic oligomer, reactive diluent and photopolymerization initiator as essential components. Resin, polyether resin, polyurethane resin, polyamide-imide resin,
You may mix | blend various modifying resins, such as a silicone resin and a phenol resin, and various additives, such as an organosilicon compound, a surfactant, and a sensitizer.

From the viewpoint of workability, the viscosity of the whole mixture is
Usually, it is desirable that the composition is prepared in the range of 1,000 to 10,000 centipoise (25 ° C).

In the present invention, the method for preparing the mixture is not particularly limited. A normal heating and stirring device is good.
The progress of the reaction can be monitored by the infrared absorption spectrum method by the disappearance of characteristic absorption (for example, 2270 cm ⁻¹ ) by isocyanate.

The amount of each component is not particularly limited in the present invention and can be optimized depending on the type of components used, the required physical and chemical properties of the coating layer, and the like.

(Optical Fiber Coating Step) The method for producing the coated optical fiber of the present invention is not particularly limited. Conventionally known fiberizing devices and ultraviolet irradiation type resin coating forming devices can be suitably used.

For example, the optical fiber preform 1 shown in FIG.
Is sent to a drawing furnace 2, heated and melted, drawn into an optical fiber (glass fiber) 3, and sent to a coating device 4 or 5 for coating an ultraviolet curable resin, which is then irradiated with ultraviolet light by an ultraviolet irradiation device 6. By irradiating with, the coating layer is cured to form the coated optical fiber 7, and the winding device 9 is pulled while pulling this.
It is possible to wind it up.

In the present invention, the material and composition of the optical fiber are not particularly limited.

The physical properties and coating thickness of the formed coating resin are not particularly limited.

Further, the coating resin may be a single layer or multiple layers,
A structure provided with a colored layer may be used. The photopolymerization initiator of the present invention can also be used in the colored layer.

In the present invention, the method for forming the multilayer resin coating layer is not particularly limited. A general coater (see, for example, JP-A-1-148733) can be preferably used.

In the present invention, the ultraviolet irradiation device is not particularly limited, and a normal device can be preferably used. For example, an irradiation wavelength of 200 to 600 and an irradiation energy density of 365 nm of 200 mW / cm ² or more can be preferably used.

[0056]

The UV-curable resin mixture for coating an optical fiber according to the present invention contains a photopolymerization initiator having a bisacylphosphine oxide skeleton to improve the curing rate in the optical fiber coating step, resulting in Increase the drawing speed.

Further, in the multi-layer coating process of the optical fiber, the coating can be performed all at once without impairing the curability.

[0058]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 (Mitsubishi Chemical P
TMG1000) and tolylene diisocyanate (2 mol) were stirred and mixed at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

The resulting urethane acrylate oligomer (60 parts) was added with 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 2,4,4-trimethylpentyl bis (2,6-) as a photopolymerization initiator. Dimethoxybenzoyl) (3 parts) was added to prepare an ultraviolet curable resin mixture.

The resin mixture thus obtained was coated and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 1 to produce a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 300
It was m / min.

Example 2 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were mixed with stirring at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

The resulting urethane acrylate oligomer (60 parts) was mixed with 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 2,4,4-trimethylpentyl bis (2,6-) as a photopolymerization initiator. Dichlorobenzoyl) (3 parts) was added to produce a UV curable resin mixture.

The obtained resin mixture was applied and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing device shown in FIG. 1 to produce a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, and the maximum speed for the coating resin to cure is 310
It was m / min.

(Example 3) Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were stirred and mixed at 60 to 70 ° C for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

The resulting urethane acrylate oligomer (60 parts) was added with 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 2,4,4-trimethylpentyl-bis (2,4,4) as a photopolymerization initiator. 6-Trichlorobenzoyl) (3 parts) was added to prepare an ultraviolet curable resin mixture.

The resin mixture thus obtained was coated and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 1 to manufacture a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 330
It was m / min.

Example 4 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were stirred and mixed at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

The resulting urethane acrylate oligomer (60 parts) was mixed with 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 2,4,4-trimethylpentyl bis (2,6-) as a photopolymerization initiator. An ultraviolet-curable resin mixture was prepared by adding dimethoxybenzoyl) (3 parts) and benzyl dimethyl ketal (1 part).

The resin mixture thus obtained was coated and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 1 to manufacture a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 350
It was m / min.

Example 5 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were mixed with stirring at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

The resulting urethane acrylate oligomer (60 parts) was mixed with 2-ethylhexyl acrylate (40 parts) as a reactive diluent and 2,4,4-trimethylpentyl-bis (2,6- Dimethoxybenzoyl) (3 parts) was added to prepare an ultraviolet curable resin mixture. The obtained resin mixture was used as an inner layer coating layer.

Further, to this urethane acrylate oligomer (60 parts), trimethylolpropane triacrylate (40 parts) as a reactive diluent and benzyl dimethyl ketal (3 parts) as a photopolymerization initiator were added, and an ultraviolet curable resin mixture was added. Was manufactured. The obtained resin mixture was used as an outer layer coating layer.

The obtained two kinds of resin mixtures were coated and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 2 to manufacture a coated optical fiber.

At this time, the thickness of the obtained inner coating layer was 3
The outer coating layer had a thickness of 30 μm.
The maximum speed for the coating resin to cure was 290 m / min.

Comparative Example 1 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were mixed with stirring at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

To the obtained urethane acrylate oligomer (60 parts), 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and benzyl dimethyl ketal (3 parts) as a photopolymerization initiator (Ciba-Geigy, Irgacure 651) Was added to produce an ultraviolet curable resin mixture.

The resin mixture thus obtained was coated and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 1 to manufacture a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 180
It was m / min.

Comparative Example 2 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were mixed with stirring at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

To the obtained urethane acrylate oligomer (60 parts), 2-ethylhexyl acrylate (40 parts) was added as a reactive diluent, and 1 part was added as a photopolymerization initiator.
-Hydroxycyclohexyl phenyl ketone (3 parts)
(Irgacure 184 manufactured by Ciba-Geigi Co., Ltd.) was added to produce an ultraviolet-curable resin mixture.

The resin mixture thus obtained was coated and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 1 to manufacture a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 160
It was m / min.

Comparative Example 3 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were mixed with stirring at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

To the obtained urethane acrylate oligomer (60 parts), 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 2 as a photopolymerization initiator were added.
-Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (3 parts) (IRGACURE 907 manufactured by Ciba-Geigy Co., Ltd.) was added to prepare an ultraviolet-curable resin mixture.

The resin mixture thus obtained was coated and cured around a fiber having a diameter of 125 μm using the drawing apparatus shown in FIG. 1 to produce a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 170
It was m / min.

Comparative Example 4 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were stirred and mixed at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

To the obtained urethane acrylate oligomer (60 parts), 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 2 as a photopolymerization initiator were added.
-Hydroxy-2-methyl-phenyl-propan-1-one (3 parts) (Darocur 1173 manufactured by Ciba-Geigy Co., Ltd.) was added to prepare an ultraviolet-curable resin mixture.

The obtained resin mixture was applied and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 1 to produce a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 170
It was m / min.

Comparative Example 5 Polyoxytetramethylene glycol having an average molecular weight of 1000 (1 mol) and tolylene diisocyanate (2 mol) were mixed with stirring at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

To the obtained urethane acrylate oligomer (60 parts), 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 4 as a photopolymerization initiator were added.
-Trimethylpentylbis (2,6-dimethoxybenzoyl) (0.07 parts) was added to prepare an ultraviolet curable resin mixture.

The resin mixture thus obtained was coated and cured around a quartz glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 1 to manufacture a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 160
It was m / min.

Comparative Example 6 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were mixed with stirring at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

To the resulting urethane acrylate oligomer (60 parts), 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 4 as a photopolymerization initiator were added.
-Trimethylpentylbis (2,6-dimethoxybenzoyl) (13 parts) was added to prepare a UV-curable resin mixture.

The resin mixture thus obtained was coated and cured around a silica glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 1 to manufacture a coated optical fiber.

At this time, the thickness of the obtained coating layer was 30 μm.
m, the maximum speed for the coating resin to cure is 350
It was m / min.

Comparative Example 7 Polyoxytetramethylene glycol (1 mol) having an average molecular weight of 1000 and tolylene diisocyanate (2 mol) were stirred and mixed at 60 to 70 ° C. for about 2 hours. 2-Hydroxyethyl acrylate (2 mol) was further added and mixed with stirring to complete the reaction while monitoring the characteristic absorption of infrared rays (2270 cm ^-1 ) by the isocyanate group.

To the resulting urethane acrylate oligomer (60 parts) was added 2-ethylhexyl acrylate (40 parts) as a reactive diluent, and 1 part as a photopolymerization initiator.
-Hydroxycyclohexyl phenyl ketone (3 parts)
(Irgakyoa 184 manufactured by Ciba-Geigy Co., Ltd.) was added to produce an ultraviolet curable resin mixture. The obtained resin mixture was used as an inner layer coating layer.

Further, to this urethane acrylate oligomer (60 parts), trimethylolpropane triacrylate (40 parts) as a reactive diluent and benzyl dimethyl ketal (3 parts) as a photopolymerization initiator were added, and an ultraviolet curable resin mixture was added. Was manufactured. The obtained resin mixture was used as an outer layer coating layer.

The obtained two kinds of resin mixtures were coated and cured around a silica glass fiber having a diameter of 125 μm by using the drawing apparatus shown in FIG. 2 to manufacture a coated optical fiber.

At this time, the thickness of the obtained inner coating layer was 3
The outer coating layer had a thickness of 30 μm.
The maximum speed for curing the coating resin was 150 m / min.

[0109]

According to the present invention, the ultraviolet curable resin is
Inclusion of a photopolymerization initiator of bisacylphosphine oxides improves the curing rate in the optical fiber coating process, and consequently increases the drawing speed of the optical fiber.

Further, in the multi-layer coating process of the optical fiber, the coating can be carried out all at once without impairing the curability.

[Brief description of drawings]

FIG. 1 shows a method for producing a coated optical fiber by melting an optical fiber preform in a drawing furnace, applying an ultraviolet-curable resin mixture for coating an optical fiber layer by layer, curing by ultraviolet irradiation, and winding the mixture. FIG.

FIG. 2 shows a method for producing a coated optical fiber by melting an optical fiber preform in a drawing furnace, simultaneously applying a plurality of ultraviolet-curable resin mixtures for coating an optical fiber, curing by ultraviolet irradiation, and winding. It is a figure.

[Explanation of symbols]

1 ... Glass optical fiber, 41 ... Optical fiber base material, 42 ...
Drawing furnace, 43a, 43b ... Single resin layer coating device, 43c ...
Multiple resin layer coating device, 44a, 44b ... UV irradiation device, 46a, 46b ... UV irradiation lamp, 47a, 47
b ... Reflecting mirror, 48 ... Resin coated optical fiber, 49 ... Winding machine.

Claims (16)

[Claims] 1. An optical coated fiber coated with an ultraviolet curable resin, wherein the resin contains at least a photopolymerization initiator of a bisacylphosphine oxide. 2. An optical fiber coated with an ultraviolet curable resin, wherein the resin contains at least an acrylate oligomer, a reactive diluent, and at least a photopolymerization initiator of a bisacylphosphine oxide. fiber. 3. The optical fiber according to claim 2, wherein the acrylate oligomer contains at least a polyol, an isocyanate, and an acrylate. 4. The optical fiber according to claim 3, wherein the polyol is polyoxytetramethylene glycol. 5. The optical fiber according to claim 3, wherein the isocyanate is tolylene diisocyanate. 6. The optical fiber according to claim 3, wherein the acrylate is 2-hydroxyethyl acrylate. 7. The reactive diluent comprises at least 2-ethylhexyl acrylate or trimethylolpropane triacrylate.
The optical fiber described in. 8. The photopolymerization initiator is represented by the following formula: (Here, when R ′ is a 2,4,4-trimethylpentyl group, R is a 2,6-dimethoxyphenyl group,
2,6-dichlorophenyl group, 2,4,6-trichlorophenyl group, 2,4,6-trimethoxyphenyl group,
Represents a group selected from a 2,6-dimethylphenyl group, a 2,4,6-trimethylphenyl group, a phenyl group and a methyl group; when R ′ is a phenyl group, R further represents a methyl group or a phenyl group; When R ′ is a 4-methylphenyl group, R is a methyl group, 2,6-dimethoxyphenyl group, 2,6-dichlorophenyl group, 2,4,6-trichlorophenyl group, 2,4,6-trimethoxyphenyl group Represents a group selected from a 2,6-dimethylphenyl group, a 2,4,6-trimethylphenyl group; when R'is a methyl group, R represents a methyl group; and when R'is an ethyl group, R represents Represents a methyl group; when R'is a propyl group, R
Represents a methyl group), and the optical fiber according to claim 2. 9. The photopolymerization initiator further comprises at least benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 as a photopolymerization initiator. An optical fiber according to claim 1, comprising one of 2-one, 2-hydroxy-2-methyl-1-phenyl-pyropan-1-one. 10. A method for producing an optical fiber, wherein at least one layer of the coating layer of an optical fiber coated with an ultraviolet curable resin contains at least a photopolymerization initiator of bisacylphosphine oxides. Method. 11. A coating layer of an optical fiber coated with an ultraviolet curable resin, wherein at least one layer of the resin comprises an acrylate oligomer, a reactive diluent, and at least a photopolymerization initiator of bisacylphosphine oxides. A method for manufacturing an optical fiber, comprising: 12. A coated optical fiber having a coating layer of an inner layer and an outer layer, wherein the inner coating layer comprises a bisacylphosphine oxide as a photopolymerization initiator. A coated optical fiber, which is formed by using an ultraviolet curable resin mixture for coating. 13. A method of manufacturing a coated optical fiber having a coating layer of an inner layer and an outer layer, wherein the inner coating layer comprises a bisacylphosphine oxide as a photopolymerization initiator. A method for producing a coated optical fiber, which is formed by using the ultraviolet-curable resin mixture for coating an optical fiber. 14. The coating layer of the inner layer and the outer layer is simultaneously cured by irradiation with ultraviolet rays.
1. The optical fiber manufacturing method described in 1. 15. The coated optical fiber according to claim 1, wherein the bisacylphosphine oxides as the photopolymerization initiator is 0.1 to 10 parts by weight. 16. The optical fiber according to claim 10, wherein the bisacylphosphine oxides as the photopolymerization initiator is 0.1 to 10 parts by weight. Production method.