JP2007003670A - Coated optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated optical fiber excellent in water resistance and fatigue resistance. <P>SOLUTION: A dense coating layer 2 composed of particulate titanium oxide is provided on the outer circumference of an optical fiber 1 made of fused quartz. Coating layers 3, 4 composed of organic materials are then provided on the outer circumference of such dense coating layer 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coated optical fiber using a quartz glass strand, and relates to a coated optical fiber excellent in water resistance and fatigue resistance.

  A coated optical fiber is known in which a coating layer made of an organic material is provided on the outer periphery of a glass fiber strand (hereinafter referred to as a quartz glass strand) mainly composed of quartz glass. A coated optical fiber is used in which a primary coating layer made of a relatively soft organic material is provided on the outer periphery, and a secondary coating layer made of a relatively hard organic material is provided on the outer periphery of the primary coating layer.

  The organic material is preferably an ultraviolet curable resin or a thermosetting resin from the viewpoint of coating speed and thin film formation. Particularly preferred is an ultraviolet curable resin.

  The ultraviolet curable resin is not particularly limited in terms of composition, but a urethane acrylate ultraviolet curable resin is preferable in terms of versatility and cost. Examples of the urethane acrylate ultraviolet curable resin include polyester urethane (meth) acrylate, polyether (meth) acrylate, and polycarbonate (meth) urethane acrylate. In particular, the organic material for the primary coating layer is preferably a urethane acrylate UV curable resin having no ethylene oxide structure in the oligomer structure.

  Although it does not specifically limit as thermosetting resin, There exist silicone type thermosetting resin, urethane type thermosetting resin, polyester type thermosetting resin, a polyimide, etc.

  Such a coated optical fiber is used for general purposes as well as the field of information communication. In addition, a plurality of coated optical fibers are gathered in various forms to form a cable, and this cable has been laid in various environments in the sinus.

  Patent Document 1 describes a method of reducing the dynamic fatigue of a quartz glass strand by limiting the water absorption rate of a coating material.

  In Patent Document 2, the tensile strength of quartz glass strands is maintained with respect to alkaline water by limiting the water absorption rate of the coating material and keeping the adhesion between the coating layer and the quartz glass strands within a certain range. A method for increasing the rate is described.

  Patent Document 3 describes a method of increasing the strength retention rate of a quartz glass strand by specifying the fiber drawing force and the antioxidant used for the coating material.

  Patent Document 4 describes a method for improving the fatigue characteristics of a quartz glass strand by limiting the moisture permeability of the secondary coating layer.

  Patent Document 5 describes a method of suppressing the strength deterioration of a quartz glass strand by limiting the pH and turbidity of an ultraviolet curable resin.

  Patent Document 6 prevents an increase in transmission loss when immersed in water by using a specific adhesion monomer as the pulling force at the interface between the quartz glass element wire and the primary coating layer or the material of the primary coating layer. A method is described.

  Patent Document 7 describes a method for improving moisture resistance and water resistance by limiting the water absorption rate, water absorption swelling rate, and heat loss of the coating layer.

  Patent Document 8 describes a method for improving water resistance by limiting the adhesion between the secondary coating layer and the colored layer (the colored layer is provided on the outer periphery of the secondary coating layer) and the pigment concentration of the colored layer. Has been.

  In addition, hermetic coated fibers are known in which carbon or metal is coated on the outer periphery of a quartz glass strand to improve hydrogen resistance, fatigue resistance, and the like.

Japanese Patent Laid-Open No. 7-215738 Japanese Patent No. 2768674 JP 2000-180676 A JP 2000-275483 A JP 2001-64040 A Japanese Patent Application Laid-Open No. 9-5587 JP 9-33773 A JP 11-31723 A

  However, maintaining stable dynamic fatigue characteristics and transmission characteristics of optical fibers over a long period of time in high temperature and high humidity or in warm water is that the water absorption rate, moisture permeability, pH, silica glass strand and primary coating of the coating material It could not be achieved by the method disclosed in the above-mentioned patent document in which the adhesion strength with the layer was devised.

  In addition, since the carbon-coated fiber uses a hydrocarbon-based gas at the time of manufacture, there is a problem that an auxiliary facility such as an exhaust gas facility is required. In addition, in carbon coated fiber, the adhesion between the carbon layer and the resin coated on the outer periphery of the carbon layer is difficult to obtain, and since the color of the carbon layer is black, the concealability by the colored layer provided for identification is weak And there is a problem that the appearance of the colored layer becomes dull.

  Accordingly, an object of the present invention is to solve the above-described problems and provide a coated optical fiber having excellent water resistance and fatigue resistance.

  In order to achieve the above object, in the present invention, a dense coating layer made of fine particle titanium oxide is provided on the outer periphery of a quartz glass strand, and a coating layer made of an organic material is provided on the outer periphery of the dense coating layer.

  It is desirable that the dense coating layer has a thickness of 1 μm or less.

  It is desirable that the fine particle titanium oxide has an average particle size of 50 nm or less.

  The organic material is preferably an ultraviolet curable resin.

  According to the present invention, a coated optical fiber excellent in water resistance and fatigue resistance can be realized.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As a result of various studies to solve the above-mentioned problems, the present applicant can fill the surface defects of the quartz glass wire and easily form a dense film to shield the contact with moisture. It has been found that it is effective to provide a dense coating layer made of fine-particle titanium oxide on the outer periphery of the quartz glass strand.

The structure of fine particle titanium oxide is not particularly limited. For example, TiO ₂ , TiO _2-X (Marukatsu Sangyo Co., Ltd.), TiO _2-X N _X (Ishihara Sangyo Co., Ltd.) and ceramics are partially covered with ceramic. Titanium oxide hybrid (Taihei Chemical Industry Co., Ltd., Showa Denko Co., Ltd.).

  The thickness of the dense coating layer is desirably 1 μm or less. When the dense coating layer is thicker than 1 μm, there is a problem that the bending loss of the coated optical fiber tends to increase. Preferably, the dense coating layer has a thickness of 10 to 500 nm, more preferably the dense coating layer has a thickness of 20 to 200 nm.

  The average particle size of the fine particle titanium oxide is desirably 50 nm or less. The average particle size of the fine particle titanium oxide is 50 nm or less. When the average particle size exceeds 50 nm, an increase in light transmission loss due to a lateral pressure or the like is promoted, and the denseness is reduced to obtain a water shielding effect. This is because it becomes difficult.

  As shown in FIG. 1, the coated optical fiber according to the present invention is provided with a dense coating layer 2 made of fine-particle titanium oxide on the outer periphery of a quartz glass strand 1 and made of an organic material on the outer periphery of the dense coating layer 2. A primary coating layer 3 is provided, and a secondary coating layer 4 made of an organic material is provided on the outer periphery of the primary coating layer 3. The organic material of the primary coating layer 3 is relatively soft. The organic material of the secondary coating layer 4 is relatively hard.

  The effect of the coated optical fiber of FIG. 1 will be described. Since the dense coating layer 2 made of fine particle titanium oxide is provided on the outer periphery of the quartz glass strand 1, the dense coating layer 2 is impermeable to water. The waterproofness of the strand 1 can be improved.

  In addition, the coated optical fiber of FIG. 1 has the dense coating layer 2 that is a dense film formed on the surface of the quartz glass element wire 1 that is glass, thereby preventing or preventing water from entering the glass. Reduced strength of glass is suppressed.

  Hereinafter, in order to confirm the effect of the present invention, coated optical fibers referred to as Example I and Example II were prepared, and for comparison, conventional coated optical fibers referred to as Comparative Example I and Comparative Example II were prepared. Thus, these samples were subjected to various tests described later to evaluate basic characteristics.

In Example I, first, photocatalytic titanium oxide (STS-01 Ishihara Sangyo Co., Ltd .; TiO ₂₎ having a particle diameter of 7 nm at a speed of 1200 m / min as a dense coating layer 2 is formed on the outer periphery of a quartz glass strand 1 having a diameter of 125 ± 1 μm. The coating was about 25 nm thick with a concentration of 30 wt% and the solvent was alcohol), and was dried by passing through a heating furnace. After that, the primary coating layer 3 is coated with a urethane acrylate UV curable resin having a Young's modulus of 1.0 ± 0.2 MPa to a thickness of 35 μm and passed through an ultraviolet irradiation device (Fusion 6 kW × 1 lamp: output 80%). The coating layer 3 was cured. Next, the secondary coating layer 4 is coated with a urethane acrylate ultraviolet curable resin having a Young's modulus of 700 ± 100 MPa to a thickness of 25 μm and passed through an ultraviolet irradiation device (Fusion 6 kW × 4 lamps: output 90%) for secondary coating. Layer 4 was cured to obtain a coated optical fiber of the present invention.

In Example II, first, photocatalytic titanium oxide (NTB-13 Showa Denko KK) having a particle diameter of 10 to 35 nm as a dense coating layer 2 at a speed of 1200 m / min on the outer periphery of a quartz glass element wire 1 having a diameter of 125 ± 1 μm; TiO ₂ concentration 3 wt%, solvent was a mixture of water and alcohol) was coated to a thickness of about 50 nm and dried by passing through a heating furnace. After that, the primary coating layer 3 is coated with a urethane acrylate UV curable resin having a Young's modulus of 1.0 ± 0.2 MPa to a thickness of 35 μm and passed through an ultraviolet irradiation device (Fusion 6 kW × 1 lamp: output 80%). The coating layer 3 was cured. Next, the secondary coating layer 4 is coated with a urethane acrylate ultraviolet curable resin having a Young's modulus of 700 ± 100 MPa to a thickness of 25 μm and passed through an ultraviolet irradiation device (Fusion 6 kW × 4 lamps: output 90%) for secondary coating. Layer 4 was cured to obtain a coated optical fiber of the present invention.

  In Comparative Example I, a conventional coated optical fiber was obtained by excluding only the step of forming the dense coating layer 2 from the step of Example I.

  In Comparative Example II, first, a carbon layer was coated in a thickness of about 20 nm on the outer periphery of a quartz glass strand 1 having a diameter of 125 ± 1 μm by using chemical vapor deposition (CVD). Then, the primary coating layer 3 and the secondary coating layer 4 were formed similarly to Example II, and the conventional carbon coat fiber was obtained.

  The tests to be performed are a bending test, initial loss test, temperature characteristic test, wet heat test, hot water test, dynamic fatigue test, and ironing test.

  In the bending test, an increase in optical transmission loss when a coated optical fiber is wound 10 times around a cylinder having a radius of 15 mm is measured with an optical power meter.

  In the initial loss test, three 1000 m bundles of coated optical fibers were prepared, and in accordance with IEC 60793-1-40 established by IEC (International Electrotechnical Commission), using an OTDR (Optical Time Domain Refractometer) method, wavelength 1 Measure optical transmission loss at .31 μm and 1.55 μm.

  In the temperature characteristic test, three bundles of 1000 m of coated optical fiber were prepared, and 10 cycles were performed at a temperature cycle of −60 ° C. to 70 ° C. (temperature change rate: 1 ° C./min) in accordance with IEC 60793-1-52. It measures changes in optical transmission loss before and after.

  For the wet heat test, three 1000m bundles of coated optical fiber were prepared, and after measuring the change in optical transmission loss before and after it was placed in an environment of 85 ° C-85% RH for 30 days in accordance with IEC 60793-1-50. To do.

  In the hot water test, three bundles of 1000 m of coated optical fiber are prepared, immersed in warm water at 60 ° C. and 80 ° C., and the change in optical transmission loss before and after that is measured.

  In the dynamic fatigue test, the dynamic fatigue coefficient (n value) of a coated optical fiber placed in an environment of 85 ° C.-85% RH for 30 days is measured by a test method based on IEC 893-1, and the n value is 20 or more. (As defined in the Bellcore standard) was accepted.

  In the ironing test, as shown in FIG. 2, two coated optical fibers 5 having a length of 100 mm are arranged on the flat plate 7 with an interval of about 20 cm, and both ends of each coated optical fiber 5 are flattened by fixing portions 8. The stainless steel rod 6 having a diameter of 5 mm is placed on the coated optical fiber 5 and adjusted so that the total weight is 200 g. The section of the coated optical fiber 5 in the longitudinal direction as shown in the figure is 30 mm. After the stainless steel rod 6 is reciprocated 50 times at a speed of 10 mm / sec, the peeling at the interface between the quartz glass element wire 1 and the coating layer (the dense coating layer 2, the primary coating layer 3, etc.) in the section where the ironing is applied The presence or absence is observed with an optical microscope.

  Table 1 shows the evaluation results of the various experiments. In the item column, the test name, conditions, measurement unit, etc. are entered. In the criteria column, criteria that can be evaluated as acceptable are entered. The measured values are written in the columns of Example I, Example II, Comparative Example I, and Comparative Example II.

  As shown in Table 1, the results of the bending test, the initial loss test, and the temperature characteristic test all satisfy the acceptance criteria for Example I, Example II, Comparative Example I, and Comparative Example II, and are compared with Examples I and II. There is no difference from Examples I and II. Moreover, although the result of 60 degreeC of a moist heat test and a warm water test has some differences in Example I and II and Comparative Examples I and II, all satisfy the acceptance criteria. However, in the result of the hot water test at 80 ° C., Examples I and II and Comparative Example I satisfy the acceptance criteria, but Comparative Example II fails. Further, in the results of the dynamic fatigue test, Examples I and II and Comparative Example II satisfy the acceptance criteria, but Comparative Example I fails. As a result of the ironing test, Examples I and II and Comparative Example I satisfy the acceptance criteria, but Comparative Example II fails.

  Thus, Examples I and II passed all the tests, Comparative Example I failed the dynamic fatigue test, and Comparative Example II failed the hot water test and ironing test. From this, the coated optical fiber of the present invention can maintain stable transmission characteristics over a long period even in warm water, and can maintain stable dynamic fatigue characteristics over a long period even under high temperature and high humidity. I can conclude.

  In addition, the coated optical fiber of the present invention does not appear dark like the carbon-coated fiber because the particulate titanium oxide is colorless and transparent.

It is sectional drawing of the coated optical fiber which shows one Embodiment of this invention. It is a block diagram of the test apparatus for an ironing test.

Explanation of symbols

1 Wire made of quartz glass 2 Dense coating layer 3 Primary coating layer 4 Secondary coating layer

Claims (4)

  A coated optical fiber, wherein a dense coating layer made of fine particle titanium oxide is provided on the outer periphery of a quartz glass element wire, and a coating layer made of an organic material is provided on the outer periphery of the dense coating layer.   The coated optical fiber according to claim 1, wherein the dense coating layer has a thickness of 1 μm or less.   The coated optical fiber according to claim 1 or 2, wherein the fine particle titanium oxide has an average particle size of 50 nm or less. The coated optical fiber according to claim 1, wherein the organic material is an ultraviolet curable resin.

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