JPH04139038A - Method and device for producing optical fiber - Google Patents

Abstract

PURPOSE:To produce a coated optical fiber having a uniform-thickness coating by extruding a coating material-contg. soln. from an orifice by liq. pressure and spraying the fine-particle coating material on the drawn optical fiber. CONSTITUTION:An optical fiber glass preform 1 is heated, melted and drawn into an optical fiber 3 by a drawing furnace 2, and the optical fiber 3 leaving the furnace 2 is immediately introduced into a spray coating vessel 10. An airless spray gun 4 having an orifice 13 is set in the vessel 10 and communicated with a resin composition supplying and pressurizing tank 8. The resin composition soln. is pressurized to about 1-100kg/cm<2> by N2 gas, etc., in the tank 8, supplied to the spray gun 4 through a line 12, depressurized, sprayed as the fine particle 14 and uniformly applied on the optical fiber 3. The coated optical fiber 3 is introduced into a resin curing furnace 5 to cure the coating layer and wound on a winder 6. Meanwhile, the diameter of the orifice of the spray gun 4 is controlled to about 50mu to 1mm, and the size of the sprayed fine particle is uniformly adjusted to about 0.2mu.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for manufacturing an optical fiber, and more particularly to a novel method for coating an optical fiber with resin and an apparatus therefor.

[Prior Art] Optical fibers are about to be put into practical use as a new transmission method because of their excellent transmission characteristics such as large capacity and low loss, as well as their non-rusting and lightweight properties. Optical fibers are made of glass and are processed to have a diameter of 200 μm or less, so mechanical strength is one of the most important properties.

In order to improve this mechanical strength, a so-called tandem primary is applied and cured immediately after the optical fiber base material is molten and drawn to maintain the virgin strength of the glass and prevent subsequent scratches. -The coat method is used.

[Problem to be solved by the invention] Conventionally, die dipping method, felt method, spray method, etc. have been used to apply this resin composition, but each method has advantages and disadvantages. In this respect, the die tipping method and the spray method are superior and are most commonly used. However, the die dipping method cannot form a coating film with a thickness of 2 to 3 μm or less, and although the spray method can achieve a thin film, it is difficult to obtain a uniform coating on the optical fiber, that is, to control the coating thickness of the resin composition. It has the disadvantage of being difficult.

Figure 3 shows a part of the conventional one-spray system, which uses compressed gas at a fairly high pressure of 50 kg/as' to 100 kg/cm'' to atomize the coating material (resin composition). , the size of the particles of the coating material is not uniform,
The coating film applied to the surface of the glass fiber was uneven, making it impossible to achieve a uniform thickness.

Additionally, when compressed gas at a fairly high pressure atomizes the coating material, a large amount of fog is generated and the coating material particles are blown away at high velocity.
There was also a drawback that about 50% of the coating material was scattered to the surroundings, resulting in a low adhesion efficiency of the coating material fine particles.

In addition, because the coating condition is not good, it is necessary to apply an extra number of times, which increases the process time, and because the adhesion efficiency is low, material costs are high.Furthermore, equipment to prevent scattering to the surrounding area is required, which requires equipment. The high cost also led to disadvantages not only in terms of quality but also in terms of shipping costs.

The present invention provides a new method and apparatus for coating optical fibers with resin, which can improve the various drawbacks of the conventional methods described above, realize a thin film with a uniform coating thickness, and reduce the cost compared to the conventional methods. This was done as a challenge.

[Means for Solving the Problems] The present inventors have found that although the one-sided spray method has a problem with uniform application, it has the advantage of being able to apply to a thickness of 2 to 3 μm or less, so it solves the problem particularly in atomization. (As a result of our research efforts, we have developed a method and device that uses the hydraulic pressure of the coating material itself to extrude and spray it from a small-diameter orifice (hereinafter referred to as the airless spray method), without the use of fairly high-pressure compressed air. The present invention was completed.

The present invention provides a method for producing an optical fiber having a coating layer by spraying coating material fine particles onto the outer periphery of a drawn glass fiber. The above problem is solved by a method characterized by spraying as fine particles.

Further, the present invention provides an apparatus for realizing the above method (a)
A drawing furnace, (11) a spray coating device comprising a spray coating device container having a through hole for passing the drawn glass fiber, and one or more sprayers provided around the outer periphery of the passing glass fiber in the container; I) Covering material curing means, (A) ~
In an optical fiber manufacturing apparatus provided in the order of (8),
The sprayer communicates with a coating material-containing solution supply device,
An optical fiber manufacturing apparatus is provided, characterized in that the coating material-containing solution is forced out of an orifice and sprayed by the hydraulic pressure of the solution.

The apparatus of the present invention enables recycling of the coating material by providing an exhaust hole for collecting unattached particles of the coating material at a position opposite to the atomizer relative to the optical fiber in the spray applicator container. .

To explain the present invention in detail with reference to the drawings, FIG. 1 is a schematic diagram showing an embodiment of the present invention, in which a glass preform (preform) for an optical fiber is heated and melted in a drawing furnace 2. The optical fiber 3 is drawn into an optical fiber 3, and the optical fiber 3 exiting the drawing furnace 2 is immediately introduced into a spray coating container. The interior of the spray application container IO is equipped with one or more sprayers (airless spray guns) 4 having an orifice 12 whose cross-sectional view is shown in FIG. composition) is connected to the supply pressurized tank 8. The resin composition supply pressurized tank 8 is supplied with N, gas, air, etc.] kg/am! When a resin composition solution pressurized to about 100 kg 7 cm' is supplied to the airless spray gun 4 through the line 12, the resin composition fine particles 14 are sprayed from the grating 13 due to the liquid pressure and are applied to the outer periphery of the optical fiber 3. Applied evenly. Subsequently, the fiber on which the coating layer has been formed is introduced into the resin curing furnace 5, and the coating layer is cured by heating or ultraviolet irradiation to form a coating layer,
It is wound up with a winding device 6. Further, the resin composition that did not adhere to the fiber in the spray coating container 10 is collected into the storage tank 9 through the collection hole 7 at the bottom of the container, and the resin composition is supplied and added via the resin composition supply/recycle line 11. Return it to the pressure tank 8 and use it repeatedly. Recovery may be done by exhausting with a pump or the like.

The orifice diameter of the airless spray gun 4 of the present invention is 5
The diameter is approximately 0 μm to 1 mm, and although one orifice is shown for simplicity in the figure, it may have a large number of orifices.

Regarding the coating material used in the present invention, materials used for coating this type of optical fiber, such as urethane acrylic,
There is no particular restriction as long as the liquid contains various resin compositions such as silicone-based, epoxy-based, fluorine-based, etc., but even the resin composition itself can be prepared by dissolving a high-viscosity resin composition in a solvent to lower the viscosity. It may be a substance or a substance dispersed in a dispersion medium. The resin composition is preferably one that can be cured by reaction with heat, ultraviolet rays, electron beams, etc., and includes, for example, urethane-acrylic, silicone-based, epoxy-based, and fluorine-based resin compositions. Further, in order to be able to spray using hydraulic pressure, the viscosity of the coating material supplied to the orifice is preferably about 500 cps or less.

In the present invention, in order to make the coating layer formed on the surface of the glass fiber a smooth thin film with no unevenness and uniform thickness, (1) use a coating material whose viscosity is lowered to about 500 cps or less by dissolving it in a solvent; (2) Spray painting by dispersing an emulsion containing fine particles of a coating material that does not dissolve in a solution through an orifice.■Use a liquid coating material that can be used as is without dissolving or dispersing it in a solvent. , etc., by various means.

[Operation] According to the present invention, coating material fine particles are attached to a drawn glass optical fiber by an airless spray method to form a coated optical fiber. By spraying only with the hydraulic pressure of the coating material without using compressed air, the size of the coating material particles can be reduced to 0.
Since it can be made into a uniform layer of about 2 μm, the coating layer formed on the surface of the glass fiber is a smooth thin film with a uniform thickness, and according to experiments by the present inventors, it is ~5 μm5.
We were able to create a thin film with a thickness of approximately μm.

In addition, since the spray is performed using only hydraulic pressure, there is no problem of scattering as in conventional methods, and the adhesion efficiency is high, reducing coating time and equipment costs. Furthermore, recovery and repeated use of the covering material are easy, and manufacturing costs can be reduced in this respect as well.

[Example] The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

Example 1 A coated optical fiber was manufactured using the apparatus configuration of the present invention shown in FIG. A glass preform is drawn at a linear speed of 200 m/inch to obtain a glass fiber 3 with an outer diameter of 125 μm, and a urethane acrylate ultraviolet curing type fiber having a diameter of about 1 μm or less is drawn from a sub-L/-tin 4 in a spray coating container 10. A coated optical fiber having a coating layer with a thickness of about 5 μm was obtained by spraying fine particles of the resin composition and then passing it through an ultraviolet curing oven. In addition, the hydraulic pressure of the coating material is 40 kg/cs
'Met.

Regarding the obtained coated optical fiber of 30 km, it was confirmed that the resin coating was formed to have a uniform thickness over the entire length in the longitudinal direction.

Comparative Example 1 A coated optical fiber was manufactured under the same conditions as in Example 1, except that in the apparatus shown in FIG. 1, a conventional spray device using compressed air was used in place of the spray gun 4 and the resin supply pressurized tank system. did. When we investigated the obtained coated optical fiber 3Qkm, we found that the resin coating covers the entire length,
The coating was uneven, with many irregularities on the surface, and there were some areas where the resin did not adhere.

[Effects of the Invention] As explained above, according to the present invention, fine particles of coating material having a uniform and stable size can be attached to the surface of a drawn glass fiber by an airless spray method, so that a smooth coating with a uniform thickness can be applied unevenly. It is possible to produce a coated optical fiber formed without the need for a coated optical fiber. The apparatus of the present invention is advantageous in that it can produce coated optical fibers with simple equipment, with good adhesion efficiency and recovery rate of the coating material, and at reduced costs.

[Brief explanation of the drawing]

1st rI! J is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a cross-sectional view schematically showing the spray gun portion of the airless spray device of the present invention, and FIG. 3 is a cross-sectional view showing a conventional spray method. In the figure, 1 nib form, 2: drawing furnace, 3: optical fiber, 4: airless spray gun, 5: If oil curing furnace, 6
: Winder, 7 Resin composition recovery device, 8/## Fat composition supply pressurized tank, 9: Resin composition storage tank, IO: Spray coating container, 11: Resin composition supply/recycle line, 12: Pressurized resin composition supply line, 13: Niorifice, 14:41 Fat composition fine particles, 15: Conventional method sprayer,
shows.

Claims (3)

[Claims] (1) In a method of manufacturing an optical fiber having a coating layer by spraying coating material fine particles onto the outer periphery of a drawn glass fiber, the coating material is formed by extruding a solution containing the coating material from an orifice using the liquid pressure of the solution. A method for manufacturing an optical fiber, characterized by spraying it as fine particles. (2) (a) a drawing furnace; (b) a spray applicator container having a through hole for passing the drawn glass fiber; and one or more sprayers provided in the container around the outer periphery of the passing glass fiber. In an optical fiber manufacturing apparatus comprising a spray coating device and (c) a coating material curing means in the order of (a) to (c), the sprayer communicates with a coating material-containing solution supply device, and the coating material-containing solution supply device An optical fiber manufacturing apparatus characterized in that the solution is forced out of an orifice and sprayed by the hydraulic pressure of the solution. (3) The optical fiber according to claim (2), wherein the spray coating device container has an exhaust hole for collecting coating material fine particles that have not adhered to the optical fiber at a position opposite to the sprayer. Fiber manufacturing equipment.