JP2005148373A - Frp made tension member and drop optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an FRP made tension member which is hardly broken when it is bent by a large radius. <P>SOLUTION: A cable 1 is provided with a coated optical fiber 2, coated tension members 3 and a messenger wire 4. Each of the coated tension members 3 is formed into a flat rectangular cross section in which a fiber-reinforced thermosetting resin made tension member 5 is coated by a thermoplastic resin coating layer 6. A pair of the coated tension members 3 is arranged coaxially above and below the coated optical fiber 2 at prescribed intervals to interpose the coated optical fiber 2 therebetween. As a reinforcing fiber of the tension member 5, an appropriate one is selected from the followings, for example, aramid fiber, polyarylate fiber and polyparaphenylene benzobisoxazole (PBO) fiber or the like provided that the elastic modulus in tension is equal to or greater than 360 cN/dtex and the degree of stretching at the breaking point is equal to or greater than 3.5%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical fiber cable in which an optical fiber core wire and a tensile body are collectively covered with a thermoplastic resin, in particular, a non-metallic drop that is lightweight, can be reduced in diameter, has a small bending radius, that is, has excellent layability. The present invention relates to an FRP tensile member suitable for an optical fiber cable and a drop optical fiber cable using the same.

  With the arrival of an information society, the transmission information capacity of the Internet and the like has increased, and the FTTH system in which optical fiber cables are laid to subscribers such as buildings and houses is rapidly progressing.

  As a drop optical fiber cable for FTTH, one using a metal wire as a strength member has been proposed. However, if a metal wire is used as the strength member, grounding is required to cope with a lightning surge.

  In order to take the ground, it takes time for the construction, and the burden of the construction cost accompanying it, which becomes an obstacle to the spread to each home. Therefore, there has been a demand for a non-metallic drop optical fiber cable that employs a non-metallic tensile body that eliminates the need for grounding work.

  As a non-metallic type tensile body used for this type of optical fiber cable, a fiber reinforced synthetic resin (FRP) made of linear material can be raised, but instead of using a metal wire tensile body, simply using an FRP wire. , It is difficult to bond the main body coating with the thermoplastic resin, and if the bonding is insufficient, it will cause an increase in optical transmission loss due to thermal history and abnormalities such as disconnection, and it will not function sufficiently as a drop optical fiber cable. .

  In this case, it is possible to reinforce the adhesive force by applying an adhesive to the outer periphery of the cured FRP wire or by covering with an adhesive resin, but this increases the man-hours and material costs. Incurs an increase in cost, is not a good idea, and if the adhesion to the FRP is too strong, it is difficult to peel off the covering portion for securing to the termination cabinet at the time of connection work.

  By the way, the present applicant has previously disclosed a method for producing a rod-shaped article made of a thermoplastic resin-coated fiber-reinforced synthetic resin in which an FRP interface and a thermoplastic resin coating are anchored. (See Patent Document 2)

  In this manufacturing method, an uncured reinforcing core portion obtained by impregnating a reinforcing fiber bundle with an uncured thermosetting resin is coated with a molten thermoplastic resin, and then the coating layer of the thermoplastic resin is immediately cooled. After solidifying, lead this to a curing tank of pressurized high-temperature steam, soften the interface part of the reinforcing core and the coating layer, heat and cure the thermosetting resin while in contact in a fluid state, The coated thermoplastic resin is cooled to anchor-bond the core interface made of fiber reinforced thermosetting resin (FRP) and the coated thermoplastic resin.

  However, when the rod-like material obtained by such a manufacturing method is used as a strength member of a drop optical fiber cable, there is a technical problem described below.

According to the manufacturing method disclosed in the above-mentioned publication, for example, when glass fiber is used as a reinforcing fiber, unsaturated polyester is used as a thermosetting resin, and it is covered with polyethylene, the rod-like product is 106 kg / cm ^2. Although an adhesive strength of about (10 MPa) is obtained, there is a problem that the coated surface is not necessarily smooth and it is difficult to obtain a uniform and thin diameter.

  Accordingly, the present applicant is particularly interested in a drop optical fiber cable in which an optical fiber core wire and a fiber reinforced thermosetting resin (hereinafter sometimes referred to as FRP) tensile body are collectively covered with a thermoplastic resin. A non-metallic drop optical fiber cable having characteristics suitable for a drop wire has been developed, and this is proposed in Japanese Patent Application No. 2002-326513.

However, according to subsequent studies, the invention according to this application also has the technical problems described below.
JP 2001-337255 A Japanese Examined Patent Publication No. 63-2772

  That is, the strength body made of FRP has a technical problem that it easily breaks with a larger bending diameter than that of a metal body. In order to reduce the bending diameter leading to breakage, the FRP diameter may be reduced. However, when the reinforcing fibers are the same, there is a problem that the tensile strength decreases.

  In this case, improvement in tensile strength alone can be solved by replacing the reinforcing fiber with a high-strength and high-modulus type, but it also has a function (anti-shrinkage) that suppresses the shrinkage of the resin that constitutes the main body due to changes in environmental temperature. Therefore, as a means for reducing the contact area with the main body resin (anti-shrinkage property is difficult to function), it is not preferable to reduce the diameter, and the FRP tensile strength body having the same diameter and a small bending radius as before. Necessity was requested.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an FRP strength member and a drop optical fiber cable that are not easily broken at a large bending diameter. is there.

  In order to achieve the above object, according to the present invention, in a tensile strength body made of FRP in which reinforcing fibers are bound with a thermosetting resin, the tensile elastic modulus of the reinforcing fibers is 360 cN / dtex or more and elongation at break is obtained. The degree was set to 3.5% or more.

The thermosetting resin can be composed of a vinyl ester resin.
Drop light having a coated tensile body in which a coating layer made of a thermoplastic resin is applied to the FRP tensile body, and a main body covering portion that collectively coats the optical fiber core and the coated tensile body with a thermoplastic resin. In the fiber cable, the outer periphery of the covering layer and the body covering portion are fused and bonded to each other, and the inner periphery of the covering layer and the outer periphery of the strength member are anchored.
The thermoplastic resin coating layer can be composed of LLDPE.

  According to the FRP tensile body according to the present invention, an FRP tensile body having a small bending radius can be obtained without lowering the required tensile strength and compressibility. By using this FRP tensile body, laying can be performed. A drop optical fiber cable excellent in performance can be obtained.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.

  1 and 2 show an embodiment of an FRP strength member according to the present invention and a drop optical fiber cable using the strength member. The drop optical fiber cable 1 shown in these drawings includes an optical fiber core wire 2, a coated tensile body 3, and a messenger wire 4.

  The coated tensile body 3 is formed in a flat rectangular cross section in which a tensile body 5 made of fiber reinforced thermosetting resin is coated with a coating layer 6 made of a thermoplastic resin, and the pair of coated tensile bodies 3 are optical fibers. The core wire 2 is arranged coaxially with a predetermined interval in the vertical direction so as to sandwich it.

  The messenger wire 4 is disposed above and below one of the coated tensile bodies 3, and the optical fiber core wire 2, the coated tensile body 3, and the messenger wire 4 are configured to be collectively covered with a main body coating portion 7 made of a thermoplastic resin. I have. A pair of notches 8 are formed on the body covering portion 7 so as to face each other on both sides of the optical fiber core wire 2. Further, the messenger wire 4 is connected by a narrow width portion 9 so as to be separable from other portions.

  The drop optical fiber cable 1 constructed as described above is installed between utility poles using the messenger wire 4, and when pulling into the subscriber's house, first, the narrow portion 9 is cut as shown in FIG. Then, the messenger wire 4 is separated, then cut off from the notch 8 portion, the optical fiber core wire 2 is taken out, and the subscriber side and the core wire 2 are connected.

  In the case of this example, the coated tensile body 3 is obtained by applying a thermoplastic resin coating layer 6 to a tensile body 5 made of a fiber reinforced thermosetting resin (hereinafter referred to as FRP).

  In this case, the reinforcing fiber of the tensile body 5 is, for example, an aramid fiber, a polyarylate fiber, a polyparaphenylene benzobisoxazole (PBO) fiber, etc., and has a tensile elastic modulus of 360 cN / dtex or more and at the time of breaking. Those having an elongation of 3.5% or more are appropriately selected.

  Further, in this case, when the tensile elastic modulus is 360 cN / dtex or less, the tensile strength for protecting the optical fiber core wire 2 cannot be sufficiently obtained and the role cannot be achieved.

  In addition, when the elongation at break is 3.5% or less, the FRP is difficult to bend, and it is difficult to reduce the bending radius when the drop optical fiber cable is formed.

  That is, the allowable bending radius for continuous use becomes large, and it is unavoidable to lay with a large bending radius when laying. (Indirectly, the smaller the minimum bending diameter, the smaller the bending radius {diameter} when laying can be made). The more preferable tensile elastic modulus is 480 cN / dtex or more.

  As the reinforcing fiber to be used, a so-called multifilament-shaped fiber having a single fiber diameter of 10 to 15 μm and not twisted with a plurality of yarns is desirable, and 500 to 3500 dtex is used.

  In this case, when a reinforcing fiber having a large count, that is, a reinforcing fiber exceeding 3500 dtex is used, the roundness of the FRP is adversely affected, and a uniform coating is performed in the subsequent thin-wall coating molding process using a thermoplastic resin. Becomes difficult.

  Further, the alignment of the single yarn becomes worse, and there is a possibility that the tensile performance becomes insufficient when it is made into FRP. On the other hand, yarns of 500 dtex or less are also commercially available, but the process becomes complicated and the cost increases, which is not economical.

  The thermosetting resin that can be used for binding the reinforcing fiber of the present invention is generally a terephthalic acid-based or isophthalic acid-based unsaturated polyester resin, a vinyl ester resin (such as an epoxy acrylate resin), or an epoxy resin. These are used by adding a curing catalyst or the like, and vinyl ester resins (such as epoxy acrylate resins) are particularly preferred from the viewpoint of physical properties such as heat resistance.

  When the thermoplastic resin used for the coating layer 6 of the uncured reinforcing core portion is selected from resins compatible with the thermoplastic resin of the main body covering portion 7, and when using a flame retardant resin for the main body covering portion 7, In order to improve compatibility with the resin, it is desirable to use an adhesive resin, or add an adhesive resin masterbatch, and add a coloring masterbatch according to the color of the body cover. It may be colored.

  Moreover, the thermoplastic resin used for the coating layer 6 may have been subjected to various modifications for imparting flame retardancy in accordance with the flame resistance of the main body coating portion 7. Further, the thermoplastic resin used for the coating layer 6 is desirably an at least inner periphery in a molten or soft state when the thermosetting resin is heat-cured in order to obtain an anchor adhesion structure with the FRP portion, and a curing temperature of 110 A polyolefin-based resin having a melting point or a softening point in a range of ˜150 ° C. is more preferable.

  In addition, when the glass fiber is used as the reinforcing fiber, the FRP part is desirably a fiber-reinforced thermosetting resin cured product having an outer diameter of 0.9 mm or less from the viewpoint of bending resistance and diameter reduction (more preferably 0.6 mm or less), the point of reducing the diameter, and the case where flame resistance is not imparted to the coating layer 6, and when flame resistance is required for the main body resin, the coating thickness more than necessary is flame retardant. Therefore, the coating layer 6 is desirably 0.3 mm or less.

  Furthermore, the thickness of the coating layer 6 is preferably 0.08 mm or more before the diameter adjustment, and by adjusting the diameter of the surface layer for the purpose of reducing the diameter, the thickness is about 0.07 to 0.2 mm. It is more desirable to do.

  For thinning of the coating thickness before diameter adjustment, a resin with good thin film moldability is desirable, and for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and the like are suitable.

  The shape of the FRP coated tensile strength body 3 of the present invention is not particularly limited, but it is formed in a flat cross section such as an ellipse or a rectangle, and in particular, the direction in which the drop optical fiber cable 1 is bent (in FIG. The bending radius can be made smaller and the laying performance can be further improved by arranging the thickness of the FRP strength member 3 small (see FIGS. 1 and 2).

  FIG. 4 shows another embodiment of the FRP strength member according to the present invention and a drop optical fiber cable using the strength member. The same or corresponding parts as those in the above embodiment are given the same numerals. In the following, only the feature points will be described in detail.

  The drop optical fiber cable 1a shown in the figure includes an optical fiber core wire 2a, a coated tensile body 3a (3b), and a messenger wire 4a.

  The coated tensile body 3a (3b) is formed in a circular cross section in which a tensile body 5a made of fiber reinforced thermosetting resin is covered with a coating layer 6a made of a thermoplastic resin, and a pair of coated tensile bodies 3a (3b). However, they are arranged on the same axis with a predetermined interval above and below the optical fiber core wire 2a so as to sandwich this.

  The messenger wire 4a is arranged above and below one of the coated tensile members 3a (3b), and the optical fiber core wire 2a, the coated tensile member 3a (3b), and the messenger wire 4a are made of a thermoplastic resin body covering portion 7a. It is equipped with the structure which covered by lump. A pair of notches 8a are formed on the body covering portion 7a so as to face each other on both sides of the optical fiber core wire 2a.

  Further, the messenger wire 4a is connected by a narrow width portion 9a so as to be separable from other portions, and such a configuration is substantially the same as the above embodiment.

  As the reinforcing fiber of the tensile body 5a, for example, an aramid fiber, a polyarylate fiber, a polyparaphenylene benzobisoxazole (PBO) fiber, etc., the tensile elastic modulus is 360 cN / dtex or more, and the elongation at break Is selected as appropriate. Even in the embodiment configured as described above, the same effects as the above-described embodiment can be obtained.

  Specific examples of the present invention will be described below, but the present invention is not limited to the above-described examples or the following specific examples.

Example 1

Elongation at break in a resin impregnation tank in which a thermosetting catalyst (manufactured by Kayaku Akzo, Cadox B-CH50: 4 parts, Kayabutyl B: 1 part) is added to vinyl ester resin (manufactured by Japan Composite: Esther H8100) One multifilament of 4.6%, para-aramid fiber with a tensile modulus of 520 cN / dtex (Teijin: Technora T240, single yarn diameter 12 μm, 1670 dtex) is guided through a guide, and then the inner diameter is stepped. Then, the uncured resin is drawn by drawing it to a squeezed nozzle, and a thin rod-shaped product having an outer diameter of 0.5 mm is obtained. LLD with MI = 2.4 with master batch added, density 0.921 g / cm ³ , 1% modulus by 30 μm cast film is 170 MPa A PE resin (manufactured by Nihon Unicar Co., Ltd .: TUF2060) was coated in a ring shape with a coating thickness of 0.25 mm, and immediately led to a cooling water bath to cool and solidify the surface coating.

  Subsequently, the coated uncured linear material is guided at a speed of 15 m / min to a pressurized steam curing tank having a length of 18 m provided with pressure seal portions at the inlet and outlet, and at a steam pressure of 32.5 Pa (145 ° C.). Cured and subsequently led to a diameter adjuster equipped with diameter adjusting dies having an inner diameter of 1.0 mm and a diameter of 0.8 mm heated stepwise to 210 ° C. to 250 ° C. A coated tensile strength body 3a having a circular cross section of 0.8 mm was obtained and continuously wound around a bobbin. Subsequently, the bobbin was subjected to a drying heat treatment (secondary heat treatment) for 40 hours in a constant temperature room at 40 ° C.

  The coated tensile strength body 3a has a reinforcing fiber content of the FRP portion of 61.5 VOL%, and has a minimum bending diameter (the coated tensile strength body is looped and bent so that the loop becomes smaller, and bending fracture occurs. The immediately preceding loop diameter was 6 mm.

Example 2

  Except for the use of one multifilament of para-aramid fiber (manufactured by Toray DuPont: Kevlar 29, single yarn diameter 12 μm, 1670 dtex) having a breaking elongation of 3.6% and a tensile elastic modulus of 490 cN / dtex as the reinforcing fiber. A coated tensile body 3b having a circular cross section was obtained in the same manner as in Example 1.

  In this coated tensile body 3b, the reinforcing fiber content of the FRP portion is 58.9 VOL%, and the minimum bending diameter (the coated tensile body is made into a loop shape and bent so that the loop becomes smaller, bending breakage occurs. The immediately preceding loop diameter was 5 mm.

  The coated tensile strength members 3a and 3b obtained in Examples 1 and 2 were each subjected to a heat-resistant bending diameter test for 24 hours at 80 ° C., and 30 mm was cleared, and a sample length of 1000 mm was −30 ° C.-80. The heat cycle test at 0 ° C. was repeated three times, and the adhesion state between the coating layers 6a and 6b of the coated tensile members 3a and 3b and the FRP tensile members 5a and 5b was observed. Good results were obtained.

  Next, as a messenger wire 4a, a Φ1.2mm bluing single steel wire, two coated tensile members 3a obtained in Example 1, and a 0.25mm single-mode fiber as an optical fiber core wire 2a are crossheaded. A hot water cooling tank which is led to a die, is made of flame-retardant PE (manufactured by Nihon Unicar: NUC9739) as a forming resin of the main body covering portion 7a, and is extruded and covered with a base having a shape as shown in FIG. Then, the secondary cooling was performed in a water-cooled tank to obtain a drop cable 1a having a cross-sectional structure as shown in FIG.

  In order to confirm the layability of the obtained drop cable 1a, as shown in FIG. 5, when it was laid at the corner of the wall at r = 15 mm (diameter 30 mm), the problem such as breakage of FRP did not occur and it was good. Showed a good result.

Comparative Example 1

  Except for using one multifilament of para-aramid fiber (Toray DuPont: Kevlar 129, single yarn diameter 12 μm, 1670 dtex) having a breaking elongation of 3.3% and a tensile elastic modulus of 670 cN / dtex as the reinforcing fiber. A coated tensile member was obtained in the same manner as in Example 1.

  This coated tensile body has a reinforcing fiber content of 58.9 VOL% in the FRP part, and has a minimum bending diameter (just before the bending fracture occurs by bending the coated tensile body into a loop shape and making the loop smaller). The loop diameter was 8 mm.

Comparative Example 2

  Except for using one multifilament of a para-aramid fiber (Toray DuPont: Kevlar 49, single yarn diameter 12 μm, 1580 dtex) having a breaking elongation of 2.4% and a tensile modulus of 780 cN / dtex as the reinforcing fiber A coated tensile body was obtained in the same manner as in Example 1.

  This coated tensile body has a reinforcing fiber content of 55.8 VOL% in the FRP part, and has a minimum bend diameter (just before the bending fracture occurs when the coated tensile body is looped and bent so that the loop becomes smaller). The loop diameter was 10.5 mm.

Comparative Example 3

  Except for the use of 14 glass yarns (manufactured by Nitto Glass Fiber: ECE2251 / 0 1.0Z R41 T, 22.5 tex / piece) having a breaking elongation of 4.0% and a tensile elastic modulus of 250 cN / dtex as the reinforcing fibers. A coated tensile body was obtained in the same manner as in Example 1.

  This coated tensile body has a reinforcing fiber content of the FRP portion of 63.2 VOL%, and has a minimum bending diameter (just before the bending fracture occurs by bending the coated tensile body into a loop shape and making the loop smaller). The loop diameter was 11 mm.

  According to the FRP tensile body according to the present invention, an FRP tensile body having a small bending radius can be obtained without lowering the required tensile strength and compressibility. By using this FRP tensile body, laying can be performed. Since a drop optical fiber excellent in performance can be obtained, it can be effectively used when laying in a subscriber house.

It is sectional drawing which shows an example of the drop optical fiber cable using the strength member made from FRP concerning the present invention, and the strength member. It is explanatory drawing at the time of laying the drop optical fiber cable shown in FIG. It is explanatory drawing of a nozzle | cap | die used when forming the main body coating | coated part of the drop optical fiber cable shown in FIG. It is sectional drawing which shows the other example of the drop optical fiber cable using the strength member made from FRP concerning the present invention, and the strength member. It is explanatory drawing at the time of confirming the bending layability of the drop optical fiber cable concerning this invention.

Explanation of symbols

1, 1a drop optical fiber cable 2, 2a optical fiber core wire 3, 3a coated tensile body 4, 4a messenger wire 5, 5a tensile body 6, 6a coating layer 7, 7a main body coating portion

Claims (4)

In the FRP tensile body in which the reinforcing fiber is bound with a thermosetting resin,
A tensile strength member made of FRP, wherein the reinforcing fiber has a tensile modulus of elasticity of 360 cN / dtex or more and an elongation at break of 3.5% or more.   The FRP tensile strength body according to claim 1, wherein the thermosetting resin is a vinyl ester resin. A coated tensile body obtained by coating the FRP tensile body according to claim 1 or 2 with a coating layer made of a thermoplastic resin, and an optical fiber core and the coated tensile body are collectively coated with the thermoplastic resin. A drop optical fiber cable having a main body covering portion,
A drop optical fiber cable, wherein an outer periphery of the covering layer and the body covering portion are fused and bonded to each other, and an inner periphery of the covering layer and an outer periphery of the strength member are anchored.   The drop optical fiber cable according to claim 3, wherein the thermoplastic resin coating layer is LLDPE.

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