JP2013091575A - Method for manufacturing optical fiber and optical fiber obtained by the manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing optical fiber, which can obtain an optical fiber having excellent adhesion while maintaining efficient productivity and to provide the optical fiber obtained by the manufacturing method.SOLUTION: There is provided the method for manufacturing optical fiber for coating the optical fiber obtained by drawing a heated and melted glass preform by a resin composition containing a silane coupling agent. The method includes steps of: (a) heating and melting the glass preform in a furnace and drawing the glass preform to obtain the optical fiber; (b) cooling the obtained optical fiber and applying it with an acidity imparting material; and (c) coating the optical fiber to which the acidity imparting material is applied with the resin composition for curing.

Description

  The present invention relates to a method of manufacturing an optical fiber in which a coating layer is formed by coating a resin composition on the outer periphery of an optical fiber made of quartz glass, and an optical fiber obtained by the method.

  The optical fiber strand usually has a structure in which an optical fiber made of silica glass is coated with a resin layer. Generally, such an optical fiber is manufactured by drawing an optical fiber by drawing a quartz glass base material heated and melted in a furnace, and then passing the optical fiber through a coating die containing a resin. For example, the curable resin composition is applied to the outer periphery thereof and cured.

  As described above, the optical fiber after drawing is coated with the resin composition, but if the temperature of the optical fiber is too high, it is difficult to apply the resin composition. A process is in place. For example, Patent Document 1 proposes a method for efficiently cooling an optical fiber after drawing, and an optical fiber cooling device therefor.

On the other hand, in the optical fiber, an interface adhesion force between the coating resin layer and the optical fiber is required. Therefore, a silane coupling agent is added to the resin composition to improve the adhesion between the optical fiber and the glass surface (for example, Patent Document 2).

JP 2004-250292 A JP 59-92947 A

  An object of the present invention is to provide an optical fiber manufacturing method capable of obtaining an optical fiber with good adhesion between glass and a resin coating layer while maintaining efficient productivity, and manufacturing thereof. It is to provide an optical fiber obtained by the method.

  The inventors of the present invention focused on the fact that the silane coupling agent in the resin composition forms a protective layer on the glass surface of the optical fiber by performing a hydrolysis reaction and a dehydration condensation reaction. And in these hydrolysis reaction and dehydration condensation reaction, as shown in FIG. 2, the knowledge that the reaction rate is increased on the acid and base sides is obtained, and in order to improve adhesion, a resin composition used for coating is used. It was considered to be acidic.

However, when the resin composition is acidified, the viscosity becomes very high. For example, when application is attempted through a coating die containing the resin through an optical fiber, the resin is cut at the time of application, so the resin composition is uniformly applied to the optical fiber There was a bug that it was not possible. Accordingly, the inventors of the present invention have found that the surface of the optical fiber that is the coated surface is made acidic, instead of making the resin composition itself acidic.
The present invention has been achieved based on the above findings.

That is, the present invention is as follows.
[1] An optical fiber manufacturing method for coating an optical fiber obtained by drawing a heated and melted glass preform with a resin composition containing a silane coupling agent,
(A) a step of heating and melting a glass base material in a furnace and drawing the glass base material to obtain an optical fiber;
(B) cooling the obtained optical fiber and applying an acidifying substance; and
(C) A method for producing an optical fiber, comprising a step of coating and curing a resin composition on an optical fiber coated with an acid-imparting substance.

[2] The method for producing an optical fiber according to [1], wherein in the step of applying the acid imparting substance, a liquid containing acetic acid or formic acid is sprayed.

[3] An optical fiber that is manufactured by the method for manufacturing an optical fiber according to [1] or [2].

  According to the method for manufacturing an optical fiber of the present invention, by applying an acid-imparting substance to the surface of an optical fiber obtained by drawing, adhesion between glass and a coating resin layer is maintained while maintaining efficient productivity. An optical fiber having good properties can be obtained.

It is a schematic diagram which shows an example of the apparatus which concerns on the manufacturing method of the optical fiber strand of this invention. It is a graph which shows the relationship between the rate of hydrolysis reaction of a silane coupling agent, and dehydration condensation reaction, and pH.

As described above, the optical fiber strand manufacturing method of the present invention is an optical fiber strand that covers an optical fiber obtained by drawing a heated and melted glass preform with a resin composition containing a silane coupling agent. It is a manufacturing method, Comprising: The following processes are included.
(A) A step of heating and melting a glass base material in a furnace and drawing the glass base material from the lower end of the furnace to obtain an optical fiber. (B) Cooling the obtained optical fiber and applying an acid-imparting substance. Step (c) A step of coating and curing a resin composition on an optical fiber coated with an acid-imparting substance

  Hereinafter, a preferred embodiment of a method for manufacturing an optical fiber according to the present invention will be described in detail with reference to a schematic diagram (FIG. 1) of an example of an apparatus used in the method for manufacturing an optical fiber according to the present invention. explain.

  As shown in FIG. 1, in the apparatus according to this embodiment, an optical fiber cooling device 14 is disposed below a drawing furnace 11 that heats a glass base material 12, and an acid imparting substance application unit 16 is disposed below the apparatus. Is provided. A coating die 17 storing an curable resin composition and an ultraviolet irradiation device 18 are disposed immediately below the acid imparting substance application unit 16. The optical fiber 1 before coating with the resin composition and the optical fiber 4 after coating with the resin composition are also shown in FIG.

1. Step (a) In the manufacturing method of the present embodiment, first, the optical fiber preform 12 heated and melted in the drawing furnace 11 is drawn out by a conventional method, and the high-temperature optical fiber 1 is obtained. The temperature of the optical fiber 1 at this time is about 800-1000 degreeC, for example.

2. Step (b) The high-temperature optical fiber 1 obtained in the step (a) is sent to the optical fiber cooling device 14 and cooled to, for example, room temperature to about 50 ° C. by the cooling gas. As the cooling gas, helium gas having a large heat transfer coefficient is preferably used, and the cooling gas is preferably supplied after cooling to room temperature or lower. Further, the cooling device has a mechanism that can efficiently cool by removing the traction flow accompanied by heat from the drawing furnace 11, for example, the flow path of the cooling gas in the cooling cylinder is rapidly expanded to A device having a mechanism capable of generating a turbulent flow and efficiently separating the traction flow accompanying the traveling of the optical fiber from the optical fiber by the turbulent flow is preferably used from the viewpoint of production efficiency.
The cooled optical fiber 1 is sent to the acid imparting substance applying unit 16 to apply the acid imparting substance. The acidity-imparting substance may contain an organic acid such as acetic acid or formic acid or may contain an inorganic acid such as hydrochloric acid. Moreover, an acid generator may be sufficient. Examples of the acid generator include a diazosulfone photoacid generator and a triarylsulfonium photoacid generator. The photoacid generator is preferably used after being dissolved in a solvent such as propylene carbonate. The acid imparting substance is preferably applied to an optical fiber so that the pH of the glass surface is 5 or less, more preferably 4 or less. For example, a 1M aqueous acetic acid solution can be preferably used. The method for applying the acid imparting substance to the optical fiber is not particularly limited, such as spraying or dipping, but spraying is preferred from the viewpoint of workability.

3. Step (c) The optical fiber coated with the acid-imparting substance in step (b) is introduced into the coating die 17 and the curable resin composition is applied. The curable resin composition is not particularly limited as long as it contains a silane coupling agent, but preferably contains a urethane acrylate ultraviolet curable resin as a main component. More specifically, it preferably contains a polymerizable oligomer having both a repeating unit structure having a urethane bond and a (meth) acryl group as a main component, and particularly, a polyol compound, a diisocyanate compound and a hydroxyl group-containing (meth) acrylate are used. More preferably, the main component is a polymerizable oligomer obtained by reacting the isocyanate group of the diisocyanate with the hydroxyl group of the polyol compound and the hydroxyl group of the hydroxyl group-containing (meth) acrylate.

  The silane coupling agent is not particularly limited as long as it does not hinder the effects of the present invention, and any silane coupling agent including publicly known ones can be used. Silicate, tetraethyl silicate, mercaptopropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxy-ethoxy) silane, β- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, γ-glycid Xylpropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) ) -Γ-aminopropyltrimethyldimethyl Xysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, bis- [3- (triethoxysilyl) propyl] Examples thereof include tetrasulfide, bis- [3- (triethoxysilyl) propyl] disulfide, γ-trimethoxysilylpropyldimethylthiocarbamyl tetrasulfide, and γ-trimethoxysilylpropylbenzothiazyl tetrasulfide.

The optical fiber coated with the resin composition is introduced into the ultraviolet irradiation device 18, and the resin composition is cured by ultraviolet irradiation. Thereby, the optical fiber 4 is manufactured.
In addition, one Embodiment of the optical fiber strand of this invention is the optical fiber strand manufactured in this way.

  Hereinafter, the result of an evaluation test is shown about Example 1 and Comparative Examples 1 and 2 which concern on this invention, and this invention is demonstrated further in detail. The present invention is not limited to these examples.

[Fabrication of optical fiber]
The resin composition used in Example 1 and Comparative Examples 1 and 2 is a resin composition containing the following urethane acrylate ultraviolet curable resin and a silane coupling agent, and all are common. In addition, the “conventional optical fiber manufacturing method” described below is to cool an optical fiber obtained by drawing a heated and melted glass base material, and then coat the optical fiber with the above resin composition. It refers to a production method that cures by ultraviolet irradiation.

[Urethane acrylate UV curable resin composition]
As urethane acrylate, polytetramethylene glycol, isophorone diisocyanate, and hydroxyethyl acrylate are reacted at a ratio of approximately 1: 2: 2. As reactive monomers, N-vinylpyrrolidone, isobornyl acrylate, EO-modified bisphenol are used. The base resin was obtained by adding the contained diacrylate. To this base resin, 3% by mass of hydroxyethylacrylamide as an amide monomer and 1% by mass of 2,4,4-trimethylpentylphosphine oxide as a photoinitiator were added to prepare a resin composition.

Example 1
An optical fiber was produced by the same method as the conventional optical fiber production method except that a step of spraying a 1M aqueous acetic acid solution on the cooled optical fiber was added.
(Comparative Example 1)
An optical fiber was produced by the same method as the conventional optical fiber production method except that a step of adjusting the pH of the resin composition to 4 by adding acetic acid to the resin composition was added (resin composition) Since the work could not be continued due to the thickening of things, it was interrupted.)
(Comparative Example 2)
An optical fiber was produced by a conventional optical fiber manufacturing method.

[Evaluation]
About Example 1 and Comparative Examples 1-2, the evaluation test was done as follows about the viscosity of the resin composition at the time of preparation, and the adhesiveness and dynamic fatigue characteristic of the obtained optical fiber. The results are shown in Table 1.
(Test method)
1. Viscosity of the resin composition The viscosity of the resin composition is observed from the viewpoint of workability, and the one that can be uniformly applied to the optical fiber with a certain thickness (viscosity of 5.0 Pa or less at 35 ° C.) Those that cannot be applied to the film (viscosity exceeding 5.0 Pa at 35 ° C.) were evaluated as x.
2. Adhesiveness The resin coating layer of the optical fiber is cut with a razor at a depth that the blade edge does not reach the glass surface, one resin coating layer sandwiched between the cuts is affixed to the mount, and the mount is fixed. The optical fiber was gripped and pulled. Measure the tensile strength when the optical fiber (glass part) is pulled out from the resin coating layer fixed to the mount, x less than 0.5kg, ○ from 0.5 to 1.5kg, and more than 1.5kg Was marked with x.
3. Dynamic fatigue characteristics Measured and evaluated according to the provisions of Teccordia GR-20-CORE.

  As shown in the results of Table 1 above, an optical fiber manufactured by an optical fiber manufacturing method in which an acid imparting substance (1M aqueous acetic acid solution) was applied to the cooled optical fiber (Example 1) ) Was superior in adhesion and dynamic fatigue properties as compared with an optical fiber (Comparative Example 2) produced by a conventional manufacturing method. Moreover, since it will thicken when acidifying a resin composition, the optical fiber strand was not able to be manufactured (comparative example 1).

DESCRIPTION OF SYMBOLS 1 Optical fiber, 4 Optical fiber strand, 11 Wire drawing furnace, 12 Glass base material, 14 Optical fiber cooling device, 16 Acid imparting substance application part, 17 Coating dice, 18 Ultraviolet irradiation device

Claims (3)

An optical fiber obtained by drawing a heated and melted glass base material with a resin composition containing a silane coupling agent.
(A) a step of heating and melting a glass base material in a furnace and drawing the glass base material to obtain an optical fiber;
(B) cooling the obtained optical fiber and applying an acidifying substance; and
(C) A method for producing an optical fiber, comprising a step of coating and curing a resin composition on an optical fiber coated with an acid-imparting substance.   The method for producing an optical fiber according to claim 1, wherein in the step of applying the acid imparting substance, a liquid containing acetic acid or formic acid is sprayed.   An optical fiber element manufactured by the method for manufacturing an optical fiber element according to claim 1 or 2.

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