JP5787927B2 - Overcoat core wire and optical fiber cable provided with the overcoat core wire - Google Patents

Description

  The present invention relates to an overcoat core wire and an optical fiber cable including the overcoat core wire. More specifically, in addition to having good overcoat layer coating removal power, an overcoat core wire excellent in coating removal performance under low temperature conditions after aging, and an optical fiber cable including the overcoat core wire About.

  The optical fiber is coated with a two-layer structure of a primary coating layer (primary layer) and a secondary coating layer (secondary layer), and a colored layer is provided around it, or the secondary coating layer is colored. By forming a layer, the outermost layer is an optical fiber colored core. In addition, for example, an overcoat core wire reinforced so that an outer diameter is 500 μm by providing an overcoat layer on an optical fiber colored core wire having an outer diameter of 250 μm is the visibility and identification of the core wire in a dark place. This contributes to improving operability and handling, simplifying laying work and shortening laying time.

  For such an overcoat core wire, it is necessary to remove the overcoat layer in connection or the like, but in the case of removing the overcoat layer, materials such as a silicone oil layer and a polyol are used as the overcoat layer and the colored layer. Therefore, a certain length can be removed. However, when connecting with a mechanical splice, it is necessary to remove a coating of 50 mm or more. On the other hand, the conventional overcoat core has a problem that it is difficult to remove the overcoat layer having such a length. In addition, the conventional overcoat core wire is coated at a low temperature (−20 ° C.) after aging for a long time (for example, a high temperature and humidity condition of 30 days at 85 ° C. × 85% RH, the same applies hereinafter). There was also a problem of poor removal.

  In view of such problems, overcoat core wires that can efficiently remove the overcoat layer, including low temperature conditions after aging, have been studied. For example, a primary coating layer that coats a glass optical fiber on an optical fiber, and a primary coating In the overcoat core wire in which a further resin layer is coated on the outermost layer on the optical fiber colored core wire in which the colored layer is coated on the secondary coating layer that coats the layer, in order to improve the coating removability of the overcoat layer, A technique is known in which the range of Young's modulus of the overcoat layer and the degree of cure of the inner surface of the overcoat layer are defined within a specific range (see, for example, Patent Document 1).

Japanese Patent No. 4500740

  In Patent Document 1, the range of Young's modulus of the overcoat layer and the degree of cure of the inner surface of the overcoat layer are defined, which is good in the state after manufacture, but at -20 ° C. after aging (after aging). As a result of the coating removal test, satisfactory results were not obtained.

  This invention is made | formed in view of the said subject, In addition to the coating removal force for removing the overcoat layer 50 mm or more being favorable, in addition to the coating removability at -20 degreeC after aging. An object is to provide an excellent overcoat core and an optical fiber cable including the overcoat core.

In order to solve the above-mentioned problem, the overcoat core wire according to the present invention has at least two coating layers covering the glass optical fiber formed on the outer periphery of the glass optical fiber, and the outermost layer of the coating layers is colored. An overcoat core wire in which an overcoat layer is formed on the outer periphery of an optical fiber colored core wire configured as described above, wherein the overcoat layer contains a polyol having a weight average molecular weight of 3000 to 4000, and the entire overcoat layer containing 25 to 33 wt% with respect to the Young's modulus at 23 ° C. of the overcoat layer, 40～130MPa der is, coating removal force of the overcoat layer is Ru 1.4~2.7N der It is characterized by that.

  The overcoat core wire according to the present invention is characterized in that, in the above-described present invention, the polyol is polypropylene glycol.

  An optical fiber cable according to the present invention includes the above-described overcoat core wire of the present invention.

In the overcoat cord according to the present invention, the overcoat layer contains a polyol having a weight average molecular weight of 3000 to 4000 in a specific range with respect to the entire overcoat layer, and the Young's modulus at 23 ° C. is in a specific range. It is said. As a result, when the overcoat layer of the overcoat core wire is removed, the maximum value of the coating removal force can be set within an appropriate range ( 1.4 to 2.7 N), and the overcoat layer can be an optical fiber colored core. Even if the length is 50 mm or more, the coating can be removed efficiently. Further, the present invention provides an overcoat core wire that can maintain excellent coating removal performance even at a low temperature of -20 ° C. after aging, and in addition, can prevent the occurrence of an optical fiber colored core wire after aging. Become.

  In addition, since the optical fiber cable according to the present invention includes the overcoat core wire of the present invention described above, the above-described effect can be enjoyed, and the construction can be easily performed from the taken overcoat core wire after the cable is laid. In addition, the overcoat layer can be removed, so that the optical fiber cable has excellent workability in the field.

It is sectional drawing which showed an example of the structure of the overcoat core wire which concerns on this invention. It is sectional drawing which showed the other example of the structure of the overcoat core wire which concerns on this invention.

  Hereinafter, one embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing an example of the structure of an overcoat core wire 1 according to the present invention. FIG. 2 is a sectional view showing another example of the structure of the overcoat core wire 1 according to the present invention. 1 and 2, 1 is an overcoat core wire, 10 is a glass optical fiber, 11 is a primary coating layer, 12 is a secondary coating layer, 12a is a colored secondary coating layer (FIG. 2 only), 13 is The colored layer (FIG. 1 only), 2 represents an optical fiber colored core, and 3 represents an overcoat layer.

  The overcoat core wire 1 according to the present invention includes at least two coating layers (a primary coating layer 11, a secondary coating layer 12, and a colored secondary coating layer 12a) covering the glass optical fiber 10 around the glass optical fiber 10. A colored layer 13) is formed, and an overcoat layer 3 is formed around the optical fiber colored core wire 2 formed by coloring the outermost layer of the coating layer.

  In the configuration of FIG. 1, a primary coating layer 11 (also referred to as a primary layer; hereinafter the same) around the glass optical fiber 10, and a secondary coating layer 12 (also referred to as a secondary layer) around the primary coating layer 11. The same is true), and a colored layer 13 colored around the secondary coating layer 12 is formed in this order, and constitutes the optical fiber colored core 2. The colored layer 13 is the outermost layer of the optical fiber colored core wire 2.

  On the other hand, in the configuration of FIG. 2, the primary coating layer 11 and the secondary coating layer 12 a colored around the primary coating layer 11 are formed in this order around the glass optical fiber 10. It becomes the core wire 2. Further, the colored secondary coating layer 12 a becomes the outermost layer of the optical fiber colored core wire 2.

(A) Overcoat layer 3:
The overcoat layer 3 in the overcoat core wire 1 according to the present invention is a layer formed around the optical fiber colored core wire 2. The overcoat core wire 1 reinforces the optical fiber color core wire 2 by providing an overcoat layer 3 around the optical fiber color core wire 2 so that the core wire is visible, distinguishable and easy to handle in the dark. It is intended to improve and simplify the laying work and shorten the time.

In the overcoat core wire 1 according to the present invention, the component constituting the overcoat layer 3 includes a polyol having a weight average molecular weight (M _w ) of 3000 to 4000. A polyol having such a weight average molecular weight (hereinafter sometimes simply referred to as “molecular weight”) can be present in the overcoat layer 3 without reacting with the network of the ultraviolet curable resin constituting the overcoat layer 3, The polyol swells in the dense network structure of the curable resin, and plays a role of a plasticizer for the ultraviolet curable resin. As a result, the Young's modulus of the overcoat layer 3 can be reduced, and flexibility can be imparted to the overcoat layer 3 even under low temperature conditions. In addition, the polyol bleeds to the interface between the colored layer 13 in contact with the overcoat layer 3 and the overcoat layer 3 to make the interface slip easily when the overcoat layer 3 is removed even under low temperature conditions. And if it is the range of this weight average molecular weight, since it becomes larger than the molecular weight of the colored layer 13, it does not pass through the mesh | network of the colored layer 13, and it does not transfer. Moreover, since the molecular weight of the polyol is as large as 3000 to 4000, the Young's modulus can be controlled by increasing the content of the polyol. In this way, by making the overcoat layer 3 have a polyol, it is possible to efficiently remove the coating even when the length is 50 mm or more, and the coating removal property is maintained even at a low temperature of −20 ° C. after aging. It will help you to do what you can.

  Examples of the polyol include polypropylene glycol, polyethylene glycol, and polytetramethylene glycol. Among these, those having no branched structure such as polyethylene glycol and polytetramethylene glycol are crystallized at low temperatures. There are cases where bending due to crystals occurs at the interface between the colored layer 13 and the overcoat layer 3 and causes an increase in loss. On the other hand, polypropylene glycol having a branched structure does not crystallize even at a low temperature of −60 ° C., and the effects of the above-described polyol can be reliably obtained. Therefore, it is preferable to use polypropylene glycol as the polyol.

  The weight average molecular weight of the polyol contained in the overcoat layer 3 is set to 3000 to 4000 as described above. If the weight average molecular weight of the polyol is less than 3000, the polyol may pass through the colored layer 13 in contact with the overcoat layer 3 or may be easily transferred to the sheath layer in contact with the overcoat layer 3 in the case of an optical fiber cable. There is a case where the above-mentioned effect is not achieved due to such a migration of the polyol. On the other hand, when the weight average molecular weight exceeds 4000, the viscosity increases when mixed with the ultraviolet curable resin, so that the coating amount when the overcoat layer 3 is applied is lowered, which may cause the outer diameter fluctuation. is there. Also, in order to increase the amount of coating, the viscosity can be lowered by increasing the heating temperature, etc., but if the heating temperature is increased too much, the volatilization amount of the ultraviolet curable resin will increase, causing contamination of the quartz tube etc. It may be a factor. In addition, what is necessary is just to employ | adopt the measured value by the method of measuring the molecular weight distribution, average molecular weight distribution, etc. of conventionally well-known polymeric substances, such as a gel permeation chromatograph (GPC), for the weight average molecular weight of a polyol.

  Content of the polyol contained in the overcoat layer 3 shall be 25-33 mass% with respect to the whole overcoat layer 3 (all the components which comprise the overcoat layer 3). If the content of the polyol is within such a range, the Young's modulus of the overcoat layer 3 can be easily maintained within the range of 40 to 130 MPa, and the coating removal force of the overcoat layer 3 is in an appropriate range (generally 1.4 to 3.5N) and the coating removal property after aging is also improved. In addition, protrusion of the optical fiber colored core wire 2 after aging can be prevented. On the other hand, when the polyol content is less than 25% by mass, the removability after aging is poor, and particularly when the content is less than 20% by mass, the coating removal force is in an appropriate range (1.4 to 3.5 N). ) May be higher. On the other hand, if the content exceeds 33% by mass, the coating removal force may be smaller than the proper range, and in addition, the protruding property after aging may be adversely affected.

  In the overcoat layer 3 of the overcoat cord 1 according to the present invention, the coating removal force can be set to an appropriate range by keeping the polyol in the above-described range, and is generally maintained at 1.4 to 3.5 N. be able to. The coating removal force means that the overcoat layer 3 of the overcoat core wire 1 is overcoated with a commercially available microstrip (for example, a 0.016 inch hole diameter blade manufactured by Microelectronics Inc.) with a length of 50 mm (5 cm). This refers to the force required to remove the overcoat layer 3 (coating) when removing the layer 3. Specifically, a microstrip blade is cut to a depth of 0.05 mm at a location 50 mm from the end of the overcoat core wire 1 to fix the blade, and the blade is directed toward the end of the colored optical fiber core wire 2. It moves along the axis of the colored optical fiber core 2 so that the 50 mm overcoat layer 3 is removed. In the present invention, the maximum value of the force applied at the time of coating removal is defined as the coating removal force.

  In the overcoat core wire 1 according to the present invention, the coating removal force of the overcoat layer 3 can be maintained at approximately 1.4 to 3.5 N. In the overcoat core wire 1, the maximum value of the coating removal force of the overcoat layer 3 is generally required to be 1.3 N or more. In the present invention, the maximum value is 1.4 N or more with a margin. . On the other hand, when it exceeds 3.5 N, the various characteristics after aging may be adversely affected.

  As other components constituting the overcoat layer 3, for example, UV curable resin that coats the optical fiber (glass optical fiber 10) and components generally used as an additive component thereof can be used. For example, oligomers, dilution monomers, photoinitiators, silane coupling agents, sensitizers, pigments, and other various additives can be used.

As the oligomer, for example, polyether urethane acrylate, epoxy acrylate, polyester acrylate, silicone acrylate and the like can be used. These may be used alone or in combination of two or more. The Young's modulus and glass transition temperature (T _g ) of the overcoat layer can be adjusted by the skeleton structure and molecular weight of the oligomer, and the type and addition amount of the dilution monomer described later. As will be described later, Young's modulus and glass transition temperature (T _g ) can be adjusted by reducing the molecular weight of the oligomer or increasing the functional group of the monomer.

  When using polyether-based urethane acrylate as an oligomer, for example, a polyol such as polypropylene glycol, polyethylene glycol or polytetramethylene glycol can be used as the intermediate block, but a polypropylene glycol having a branched structure should be used. Preferably, such a polypropylene glycol is used as an intermediate block, and a hydroxy compound having an unsaturated double bond that is reactive to ultraviolet rays is bonded to the hydroxyl groups at both ends thereof as aromatic components through an aromatic diisocyanate. It is preferable to use the above oligomers.

  Further, by using polypropylene glycol as a polyol and using an oligomer having polypropylene glycol as an intermediate block as an oligomer, crystallization at a low temperature of −60 ° C. is prevented, so that crystallization at a low temperature can be efficiently prevented. .

  As the oligomer to be used, those having a weight average molecular weight of 500 to 2500 are preferred, and those having a weight average molecular weight of 1000 to 2000 are particularly preferred.

  As the aromatic isocyanate, for example, aromatic diisocyanates such as tolylene diisocyanate (TDI) and isophorone diisocyanate (IPDI) can be used. Moreover, as a hydroxy type compound, hydroxyethyl acrylate (HEA) etc. can be used, for example.

  Since the viscosity of the oligomer alone may be too high, a dilution monomer can be blended mainly for viscosity adjustment. As a dilution monomer, a monofunctional monomer, a bifunctional monomer, a polyfunctional monomer, etc. can be used, for example.

  As a diluting monomer that can be added, in the monofunctional monomer, for example, PO-modified nonylphenol acrylate, isobornyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, isodecyl acrylate, polyethylene glycol acrylate, N-vinylpyrrolidone, N-vinyl Examples include caprolactam. Examples of the bifunctional monomer and polyfunctional monomer include 1-6 hexane diacrylate, bisphenol A epoxy acrylate, tripropylene glycol diacrylate, and tricyclodecane dimethylol diacrylate. One of these may be used alone, or two or more thereof may be used in combination.

  Note that the monofunctional monomer has a greater effect of lowering the Young's modulus than the bifunctional monomer and the polyfunctional monomer. This is because the monofunctional monomer has a greater effect of reducing the crosslinking points in the molecular structure than the bifunctional monomer and the polyfunctional monomer.

  When the photoinitiator absorbs ultraviolet rays, the photoinitiator is radicalized, and the unsaturated double bond of the reactive oligomer and the reactive monomer can be continuously polymerized. As the photoinitiator, for example, an alkylphenone photopolymerization initiator or an acyl phosphine oxide photopolymerization initiator can be used. These may be used individually by 1 type, or can be used in combination of 2 or more type.

  Examples of the sensitizer include triethylamine, diethylamine, N-methyldiethanolamine, 4-dimethylaminobenzoic acid, etc., and these may be used alone or in combination of two or more. can do.

  In the case of coloring the overcoat layer 3, examples of the pigment to be added include organic pigments such as phthalocyanine, quinacridone, dioxan, and benmidimidazolone, and inorganic pigments such as carbon black and titanium oxide. In addition, you may make it use the coloring material which mixed the pigment and the ultraviolet curable resin represented by the above-mentioned material as a coloring component. The content of the colorant may be appropriately determined depending on the content of the pigment contained in the colorant, the type of other components such as an ultraviolet curable resin, etc., but the entire overcoat layer 3 (components constituting the overcoat layer 3) It is preferable to set it as 2.0-3.0 mass% with respect to the whole.

  Other additives that can be added include, for example, antioxidants, ultraviolet absorbers, light stabilizers, deterioration inhibitors such as thermal polymerization inhibitors, silane coupling agents, leveling agents, hydrogen absorbers, chain transfer agents, Examples include lubricants.

  In the overcoat core wire 1 according to the present invention, the Young's modulus at 23 ° C. of the overcoat layer 3 is 40 to 130 MPa. By setting the Young's modulus at 23 ° C. in such a range, the coating removal force of the overcoat layer 3 is in an appropriate range (approximately 1.4 to 3.5 N) and the coating removal property after aging is also improved. . On the other hand, when the Young's modulus is less than 40 MPa, the external stress is affected by the protrusion and lateral pressure after aging, and when the Young's modulus is 130 MPa or more, the -20 ° C coating removal property after aging is affected. Therefore, the Young's modulus at 23 ° C. of the overcoat layer 3 is 40 to 130 MPa.

In order to adjust the Young's modulus of the overcoat layer 3 to the above-described range, for example, the component constituting the overcoat layer 3 can be adjusted. Specifically, the type of polyol constituting the overcoat layer 3, the weight average molecular weight and content, the type of oligomer, the molecular weight and content, the type and addition amount of the diluted monomer, or the type and content of other components, The Young's modulus (and glass transition temperature (T _g )) of the overcoat layer 3 can be adjusted depending on the ultraviolet curing conditions such as the irradiation amount.

For example, as a general tendency, it is possible to increase the Young's modulus or increase the glass transition temperature (T _g ) by decreasing the weight average molecular weight of the polyol or decreasing the content, and the molecular weight of the oligomer is increased. reducing and, by increasing the content or functionality of the diluent monomer to be added, it is possible to increase the high or T _g of the Young's modulus. On the other hand, if this is done, the crosslink density increases, shrinkage increases, and the coating removal force may be adversely affected. Therefore, it is preferable to adjust the balance in consideration of the balance.

In addition, it is preferable to make it the glass transition temperature ( _Tg ) of the overcoat layer 3 to be 50-70 degreeC on the high temperature side, for example, and it is especially preferable to set it as 55-65 degreeC.

  In order to maintain the characteristics of the optical fiber colored core wire 2 and the overcoat core wire 1 in general, the outer diameter of the overcoat layer 3 in the overcoat core wire 1 is also the outer diameter of the overcoat core wire 1. It is preferable to be in the range of 470 μm to 530 μm.

(B) Primary coating layer 11, secondary coating layer 12 and colored layer 13:
As described above, in the optical fiber (glass optical fiber 10), since transmission loss increases due to various external stresses and microbends generated thereby, it is necessary to protect the optical fiber from such external stresses. In general, a coating having a two-layer structure of a primary coating layer 11 and a secondary coating layer 12 is applied. The primary coating layer 11 is an inner layer that comes into contact with the quartz glass constituting the glass optical fiber 10, and a soft resin having a relatively low Young's modulus is used, and a hard resin having a relatively high Young's modulus is used for the outer layer. The secondary coating layer 12 was coated.

  Resin material that is a constituent material of the primary coating layer 11 (primary layer) and the secondary coating layer 12 (secondary layer) of the overcoat core wire 1 according to the present invention, and a constituent material of the color layer 13 of the optical fiber colored core wire 2 As mentioned above, the ultraviolet curable resin mentioned as the component constituting the overcoat layer 3 and its additives, oligomer, dilution monomer, photoinitiator, silane coupling agent, sensitizer, pigment, various additives Etc. can be preferably used. Of the additives described above, the lubricant may be added to the secondary coating layer 12 or the colored layer 13 as necessary.

  As the oligomer, for example, as the primary coating layer 11 and the secondary coating layer 12, an oligomer in which an aromatic isocyanate and hydroxyethyl acrylate are added to a polyol using polypropylene glycol, which is the same as the above-described overcoat layer 3. The Young's modulus can be adjusted by changing the molecular weight of the polyol (polypropylene glycol) in the intermediate block. The weight average molecular weight of the oligomer used is preferably 1000 to 4000 when used as the primary coating layer 11, and 500 to 2000 when used as the secondary coating layer 12. It is preferable to use 500 to 2000 when used as the colored layer 13, and 500 to 2000 when used as the colored secondary coating layer 12a. Is preferred.

  Moreover, as the oligomer which comprises the colored layer 13, the oligomer which added the aromatic isocyanate and hydroxyethyl acrylate to the polyol which uses polypropylene glycol similarly to the above-mentioned primary coating layer 11 and the secondary coating layer 12 is used. It is preferable that the Young's modulus can be adjusted by changing the molecular weight of the polyol (polypropylene glycol) in the intermediate block by using a bifunctional monomer or a polyfunctional monomer. Moreover, toughness can be raised by adding bisphenol A epoxy acrylate etc. to resin which comprises the colored layer 13, for example.

  In addition, as shown in FIG. 2, when the colored secondary coating layer 12a is the outermost layer of the optical fiber colored core wire 2 and the secondary coating layer 12 also serves as the colored layer 13, a pigment or the above-described By adding a coloring material to the secondary coating layer 12, a colored secondary coating layer 12a can be obtained.

  The Young's modulus at 23 ° C. of the primary coating layer 11 is preferably in the range of approximately 0.3 to 1.5 MPa. Moreover, it is preferable that the Young's modulus in 23 degreeC of the secondary coating layer 12 shall be about 500-1500 Mpa. The Young's modulus at 23 ° C. of the colored layer 13 is preferably in the range of about 1000 to 2500 MPa. In addition, when the secondary coating layer 12 serves also as the colored layer 13, it is preferable that the Young's modulus at 23 degreeC of this colored secondary coating layer 12a shall be 500-1500 Mpa.

  The outer diameter of each layer in the optical fiber colored core wire 2 is generally 80 μm to 125 μm in outer diameter of the primary coating layer 11 in order to maintain the characteristics as an optical fiber (see below). The diameter is preferably 120 μm to 200 μm, the outer diameter of the secondary coating layer 12 is preferably 165 μm to 242 μm, and the outer diameter of the colored layer 13 is preferably in the range of 135 μm to 255 μm. Further, as shown in FIG. 2, when the secondary coating layer 12 also serves as the colored layer 13, the colored secondary coating layer 12a preferably has an outer diameter in the range of 135 μm to 255 μm. .

(C) Manufacturing method of overcoat core wire 1:
An example of the manufacturing method of the overcoat core wire 1 which concerns on this invention is demonstrated. In the following, an optical fiber made of silica glass (glass optical fiber 10) coated with the primary coating layer 11 and the secondary coating layer 12 is called an optical fiber.

  In order to manufacture the overcoat core wire 1 according to the present invention, for example, first, a preform mainly composed of quartz glass is heated and melted in a drawing furnace to obtain an optical fiber made of quartz glass (glass optical fiber 10). To do. Next, a component containing a liquid ultraviolet curable resin is applied to the glass optical fiber 10 using a coating die, and then ultraviolet rays are applied to the component containing the ultraviolet curable resin applied by the ultraviolet irradiation device (UV irradiation device). Irradiate to cure such components. In this way, an optical fiber strand in which the glass optical fiber 10 is coated with the primary coating layer 11 and the secondary coating layer 12 is manufactured. In this way, after drawing, the outer periphery of the glass optical fiber 10 is immediately coated with a component containing an ultraviolet curable resin to form the primary coating layer 11 and the secondary coating layer 12, thereby reducing the strength of the obtained optical fiber strand. Can be prevented.

  In the next step, the optical fiber colored core wire 2 is manufactured by covering the outer periphery of the obtained optical fiber with the colored layer 13. In addition, as described above, the secondary coating layer 12 may be colored to form the optical fiber colored core wire 2 as the secondary coating layer 12 in which the outermost layer is colored.

  Then, by coating and curing the components constituting the overcoat layer 3 on the outer periphery of the obtained optical fiber colored core wire 2, the overcoat core wire 1 covered with the overcoat layer 3 is formed. Manufactured. In order to coat the overcoat layer 3 around the optical fiber colored core wire 2, for example, it is fed out from a bobbin wound with the optical fiber colored core wire 2, and pressure is applied to the components containing the polyol and the ultraviolet curable resin that are kept warm in advance. In such a state, the component is applied by passing it through a die and passing through the optical fiber colored core wire 2, and when passing through the ultraviolet irradiation device (UV irradiation device), it is irradiated with ultraviolet rays and cured. And the overcoat core wire 1 in which the overcoat layer 3 was formed can be manufactured by winding up to a bobbin with a taking-up apparatus.

  In the overcoat core wire 1 according to the present invention described above, the overcoat layer 3 contains a polyol having a weight average molecular weight of 3000 to 4000 in a specific range with respect to the entire overcoat layer 3, and at 23 ° C. Young's modulus is in a specific range. Thereby, when the overcoat layer 3 of the overcoat core wire 1 is removed, the maximum value of the coating removal force can be within an appropriate range (approximately 1.4 to 3.5 N), and the overcoat layer 3 It is quickly removed between the fiber colored core wire 2 and the coating removal of 50 mm or more can be carried out efficiently. In addition, the removability is maintained even at a low temperature of −20 ° C. after aging, and in addition, the overcoated core wire 1 can prevent the optical fiber colored core wire 2 from protruding after aging.

  The overcoat core wire 1 according to the present invention has a transmission loss (loss level) after the heat cycle and after aging of the heat cycle (for example, 10 cycles of −40 ° C. to + 80 ° C. in which one cycle is 6 hours). The same applies hereinafter) and the transmission loss after aging can be suppressed to a small level, and the transmission loss can be generally suppressed to 0.05 dB / km or less at a wavelength of 1550 nm.

  And the optical fiber cable provided with the overcoat core wire 1 according to the present invention enjoys the effect of the overcoat layer 3 described above, and the sheath such as a sheath after aging or even in a high temperature and high humidity environment. Stable coating that can prevent migration of substances between layers of the overcoat core wire 1 and the overcoat layer 3 and the overcoat layer 3 of the overcoat core wire 1 taken out from the optical fiber cable is not different from that of the cable. Removability etc. can be maintained. Therefore, the overcoat layer 3 can be easily removed from the taken overcoat core wire 1 in the construction after the cable is laid, and the optical fiber cable is excellent in workability at the site.

  The configuration of the optical fiber cable is not particularly illustrated, but is not particularly limited as long as it includes the overcoat core wire 1 according to the present invention. For example, the overcoat core wire 1 and the overcoat core wire 1 The configuration is arbitrary, such as a configuration of an optical fiber cable or the like composed of a tension member arranged in parallel with the overcoat core wire 1 on both sides in the longitudinal direction and a sheath covering the overcoat core wire 1 and the like. It can be set as the structure of a conventionally well-known optical fiber cable also including a structure other than this. In addition, for example, a so-called optical fiber drop cable configuration in which a pair of notches formed in the longitudinal direction is formed on both sides of the optical fiber cable, and a support portion with a built-in support line is disposed as necessary. I do not care.

  The configuration of the optical fiber cable is not limited to the above configuration. For example, the type and thickness of the sheath, the number and size of the overcoat core wire 1, the type, number and size of the tension member, etc. , You can choose freely. Further, the outer diameter and cross-sectional shape of the optical fiber cable, the shape and size of the notch, whether or not the notch is formed, and the like can be freely selected.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example and a comparative example, this invention is not limited to these.

[Example 1 to Example 8, Comparative Example 1 to Comparative Example 6]
Production of overcoat core:
Using the components shown in Table 1 and below, the overcoat cords shown in FIGS. 1 and 2 were produced by the methods shown in (1) and (2) below.

(1) Production of optical fiber colored core:
The outer diameter of the primary coating layer (primary layer) is 195 μm and the outer diameter of the secondary coating layer (secondary layer) is 242 μm around a glass optical fiber made of quartz glass and having an outer diameter of 125 μm. An optical fiber was coated with the composition shown. With respect to the obtained optical fiber, a colored layer was coated around the secondary coating layer in a separate process to obtain an optical fiber colored core wire having an outer diameter of 255 μm (in a configuration corresponding to FIG. 1, Example 1, Example 2, Example 5 to Example 7, and Comparative Example 1 to Comparative Example 5 are applicable).

  When the secondary coating layer (secondary layer) is colored and the secondary coating layer also serves as the colored layer, the outer diameter of the primary coating layer (primary layer) is 185 μm, and the outer diameter of the secondary coating layer is 242 μm. Each layer was coated to form an optical fiber colored core wire (in the configuration corresponding to FIG. 2, Examples 3, 4, 8, and Comparative Example 6 corresponded).

(2) Manufacture of overcoat core:
From the bobbin around which the optical fiber colored core obtained in (1) is wound, the optical fiber colored core is fed out, the direction is changed in the vertical direction by the upper guide roll, and the polyol having the content shown in Table 1 is kept warm in advance. Contains UV curable resin containing polyol around optical fiber colored core by applying pressure to component containing UV curable resin, sending to die through hose, and passing optical fiber colored core through this The ingredients were applied. In addition, after applying such a component, when passing through an ultraviolet irradiation device (UV irradiation device), the ultraviolet ray is irradiated to cure the component including the ultraviolet curable resin containing the applied polyol, did. It should be noted that the number of lamps of the UV irradiation device is increased as necessary according to the linear velocity. Then, the direction was changed by the lower guide roll, the direction was changed five times by the pass line, and the bobbin was wound by the take-up device, and the overcoat cords shown in FIGS. 1 and 2 were obtained.

In Table 1, for the overcoat layer, as the polyol, polypropylene glycol is used as a polyol having a weight average molecular weight and content (mass% with respect to the entire overcoat layer) listed in Table 1, and the other components are as follows: As an ultraviolet curable resin, an oligomer (polypropylene glycol as an intermediate block, and as a skeleton component, an oligomer in which hydroxyethyl acrylate is bonded to hydroxyl groups at both ends via tolylene diisocyanate. Hereinafter, an oligomer using polypropylene glycol is used. ), Dilutable monomer, photoinitiator, and additives are mixed in appropriate amounts, and the molecular weight and content of the oligomer so that the Young's modulus and glass transition temperature (T _g ) vary as shown in Table 1. , Type and number of functional groups in dilutable monomers, content, Use varied conditions of the ultraviolet curing amount such like, respectively, and the Examples and Comparative Examples. Moreover, as a coloring component, it added as content (mass% with respect to the whole overcoat layer) which exists in Table 1 as a coloring material (mixture composition of a pigment and an ultraviolet curing resin).

  In addition, the primary coating layer, the secondary coating layer, and the colored layer are also used by mixing appropriate amounts of oligomers, diluting monomers, photoinitiators, and additives using the above-mentioned polypropylene glycol as an ultraviolet curable resin. For the secondary coating layer and the colored layer, ultraviolet rays such as molecular weight, content, type and number of functional groups in the dilutable monomer, content, irradiation amount, etc. so that the Young's modulus varies as shown in Table 1. The curing conditions and the like were changed and used as examples and comparative examples. In addition, the coloring material containing an appropriate amount of pigment was added to the colored secondary coating layer when the colored layer and the secondary coating layer also serve as the colored layer.

[Test Example 1]
About the overcoat core wire of obtained Examples 1 to 8 and Comparative Examples 1 to 6, using the measurement method and test method shown below, “(1) Young's modulus”, “(2) “Glass transition temperature (T _g )”, “(3) coating removal power”, “(4) coating removal test under low temperature environment after aging”, “(5) visibility”, “(6) after heat cycle and Each test of “Transmission loss after aging” and “(7) Presence / absence of aging after aging” was performed for comparison and evaluation. The results are shown in Table 1.

(1-1) Young's modulus (overcoat layer):
A sample was obtained by removing the coating of the overcoat layer from the overcoat core wire with a removal tool (trade name: Microstrip, manufactured by Microelectronics) using a blade having a hole diameter of 0.016 inches. The end portion of the sample was adhered and fixed to an aluminum plate with a gel-like instantaneous adhesive (trade name: Aron Alpha (registered trademark), manufactured by Toagosei Co., Ltd.). Then, the aluminum plate part was chucked by a Tensilon universal tensile tester in an atmosphere of 23 ° C. × 55% RH, and the force at 2.5% elongation was measured at a marked line interval of 25 mm and a tensile speed of 1 mm / min. From this, the Young's modulus (tensile Young's modulus) was calculated.

(1-2) Young's modulus (colored layer + secondary coating layer, etc.):
While immersing the optical fiber colored core wire in about 7 cm fiber stripper (trade name: MILLER FO-103-S Fiber Optical Stripper, manufactured by Ripley Company) in liquid nitrogen, slowly glass with the fiber stripper. A tubular sample of a colored layer + secondary coating layer + primary coating layer or a colored secondary coating layer + primary coating layer was produced by drawing. Then, under the same conditions as in (1-1), a force at 2.5% elongation was measured at a tensile speed of 1 mm / min using a Tensilon universal tensile tester, and the Young's modulus was calculated from the measured value.

  In the tensile test, the primary coating layer is pulled together with the secondary coating layer (and the colored layer), but since the elastic modulus at room temperature of the primary coating layer is 1 MPa or less, the secondary coating layer And the Young's modulus of the colored layer is different by about three orders of magnitude, so that the influence is considered to be an error range even if the primary coating layer is present. As described above, even if the primary coating layer is combined, its existence is within an error range, and therefore, the Young's modulus was calculated using the values of only the secondary coating layer and the colored layer as the cross-sectional area.

(2) Glass transition temperature (T _g ) (overcoat layer):
Similarly to the measurement of the (1-1) Young's modulus, a sample was obtained by removing the coating of the overcoat layer of the overcoat cord using a removal tool. The tubular sample was subjected to a tensile method measurement using a DMA dynamic viscoelasticity test (trade name: RSA3, manufactured by TA) under the conditions of a frequency of 1 Hz, a distance between marked lines of 20 mm, and a temperature increase rate of 3 ° C./min. In this case, the peak values appearing on the low temperature side and the high temperature side of tan δ were measured as the glass transition temperature (T _g ).

(3) Cover removal power:
Removal tool (trade name: Microstrip, manufactured by Microelectronics) Using a blade with a hole diameter of 0.016 inches, fix the core wire to the chuck of the Tensilon Universal Tensile Tester while sandwiching the overcoat core wire with the removal tool. The other side of the wire was fixed to the chuck. Then, the length of 50 mm was measured, and the maximum value of the force required to remove the 50 mm overcoat layer was measured as the coating removal force in a 23 ° C. × 55% RH atmosphere at a tensile rate of 100 mm / min. The case where the maximum value of the coating removal force was 1.4 to 3.5 N was regarded as acceptable, and the case where it was out of the range was regarded as unacceptable.

(4) Coating removal test under low temperature environment after aging:
The overcoat core wire was aged at 85 ° C. × 85% RH for 30 days and then removed with a removal tool (trade name: Microstrip, manufactured by Microelectronics) in an atmosphere of −20 ° C.
Using a blade having a hole diameter of 016 inches, 100 coating removal tests were performed. “○” indicates that all 100 pieces have been removed, and “×” indicates that even one of the 100 pieces has not been removed.
Judged as. In addition, it was set as "x" when 50 mm removal was not able to be performed, or when the colored layer and the overcoat layer were closely_contact | adhered and the colored layer turned up or when the colored layer surface cracked.

(5) Visibility:
When the overcoat cord was left in a dark room and checked with a flashlight, etc., it was confirmed whether white and gray judgments and other colors could be judged at a glance. The case where it was able to confirm was set as "(circle)", and the case where it was not able to be confirmed was set as "x".

(6) Transmission loss after heat cycle and after aging:
Heat cycle from -40 ° C to + 80 ° C using the overcoat core wire for 10 cycles (1
(Cycle: 6 hours) The transmission loss after execution and the transmission loss after aging at 85 ° C. × 85% RH for 30 days were measured. The transmission loss is measured by using an optical pulse tester (trade name: MW9076B, manufactured by Anritsu Co., Ltd.) and measuring the transmission loss at a wavelength of 1.55 μm in the longitudinal direction by the optical backscattering loss coefficient (OTDR). Was done. Both are 15
The criterion was that the transmission loss (loss level) at a wavelength of 50 nm was 0.05 dB / km or less.

(7) Extrusion after aging:
After the aging of (6), the presence or absence of protrusion of the optical fiber colored core was confirmed from the end of the overcoat core. The case where the protrusion was 0.2 mm or less was determined as “◯”, and the case where the protrusion exceeded 0.2 mm was determined as “x”.

  In addition, regarding “overall determination”, (1-1) the Young's modulus of the overcoat layer is in the range of 40 to 130 MPa at 23 ° C., (3) the coating removal force is in the range of 1.4 to 3.5 N, ( 4) Cover removal test after aging is “◯”, (5) Visibility is “◯”, (6) Transmission loss is 0.05 dB / km or less, (7) Optical fiber colored core wire is protruding after aging The case where the presence / absence of all “◯” was satisfied was determined as “◯”, and even one of the above-mentioned items was determined as “X”.

(Composition and results)

  As shown in Table 1, the optical fiber cables of Examples 1 to 8 passed (“◯”) in the overall evaluation.

  On the other hand, in Comparative Examples 1 to 8, the Young's modulus at 23 ° C. is outside the range of 40 to 130 MPa, and the coating removal force in an atmosphere of 23 ° C. × 55% RH is 1.4 to 3.5 N. In addition, there was nothing satisfying both of the above and the ability to remove the coating under a low temperature environment after aging, and the overall evaluation was also rejected ("x").

  In addition to having good coating removal power, the present invention has excellent coating removal performance at -20 ° C. after aging, and can be effectively used as an overcoat core without protruding glass optical fiber during aging. The industrial applicability is high.

DESCRIPTION OF SYMBOLS 1 ... Overcoat core wire 10 ... Glass optical fiber 11 ... Primary coating layer (primary layer)
12 …… Secondary coating layer (secondary layer)
12a ... Colored secondary coating layer 13 ... Colored layer 2 ... Optical fiber colored core wire 3 ... Overcoat layer

Claims (3)

At least two coating layers covering the glass optical fiber are formed on the outer periphery of the glass optical fiber, and an overcoat layer is formed on the outer periphery of the optical fiber colored core wire formed by coloring the outermost layer of the coating layers. An overcoat cord,
The overcoat layer contains 25 to 33 mass% of a polyol having a weight average molecular weight of 3000 to 4000 with respect to the entire overcoat layer,
Young's modulus at 23 ° C. of the overcoat layer, Ri 40~130MPa der,
Overcoat core wire coating removal force of the overcoat layer is characterized 1.4~2.7N der Rukoto.   The overcoat core wire according to claim 1, wherein the polyol is polypropylene glycol.   An optical fiber cable comprising the overcoat core wire according to claim 1.

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