JP2006343536A - Spacer for plastic optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To approximate a coefficient of linear thermal expansion to that of a POF. <P>SOLUTION: The spacer for a plastic optical fiber cable is equipped with a tension body arranged in the center and a plurality of optical fiber storing grooves that are formed on the outer circumference of the tension body by extrusion forming of a thermoplastic resin and that are extending along the longitudinal direction. Also, the spacer has an inflection point in the tensile modulus of elasticity determined from the cross section of the tension body, wherein this inflection point exists in 0.02-0.5% which is an allowable ductility of a POF in the state of cable formation. The spacer has a coefficient of linear thermal expansion of 1×10<SP>-5</SP>to 7×10<SP>-5</SP>(1/°C), and the tensile modulus of elasticity is made smaller in the section reaching the inflection point than in the section beyond the point. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plastic optical fiber (hereinafter abbreviated as POF) cable spacer, and more particularly to a plastic optical fiber cable spacer in which the thermal expansion coefficient in the longitudinal direction is equal to or approximate to that of POF.

  With the spread of the Internet in recent years, the need to transmit high-capacity information at a high speed has increased, and the movement to install optical fibers not only in trunk lines and relay systems but also in buildings and homes has become active. ing.

  Also. In order to exchange information such as moving images at high speed in a building or at home, an optical fiber such as a LAN (local area network) has been studied.

  Conventionally, silica-based optical fibers that have been used for trunk systems and the like have excellent characteristics of low loss and wide bandwidth, but the core diameter is 8 to 10 μm for single mode fiber, and 50 to 62 for graded index fiber. .5 μm, which is very small, requires advanced technology for connection, and is expensive.

  In consideration of such conditions, among the above-mentioned technical trends, the ease of connection and low cost are evaluated, and attention is focused on POF. In the case of POF, since the core diameter is as large as 100 to 1000 μm, the cost required for connection is small, and since it is a plastic, it is highly flexible and has good handling properties and good workability.

  By the way, the form of the optical fiber cable in Japan mainly has a structure using a polyethylene optical fiber cable spacer (abbreviated as PE spacer) in order to safely accommodate and protect the optical fiber against various external forces. It has become.

  PE spacers include unidirectionally twisted and SZ twisted ones whose direction reverses at a predetermined angle. However, when the tension is applied to the cable, the tensile strength is kept so that the optical fiber does not break. The body is placed.

Further, for example, as a known technique, it is proposed that the thermal expansion coefficient of a tensile body is made close to that of a silica-based optical fiber so that the optical fiber does not break due to thermal expansion and contraction strain of the PE spacer itself. (See Patent Document 1).
Japanese Utility Model Publication No. 63-43441

  For the reasons mentioned above, the tensile strength of PE spacers used in silica-based optical fiber cables includes steel wires with high tensile modulus, glass fiber reinforced plastics (GFRP), carbon fiber reinforced as more suitable materials. Fiber reinforced synthetic resins (hereinafter referred to as FRP) such as plastics (CFRP) and aramid fiber reinforced plastics (AFRP) are often used.

  However, in the case of POF, the coefficient of thermal expansion is about two orders of magnitude larger than that of silica-based optical fiber, and if a tensile body for silica-based optical fiber is used as it is, there will be inconvenience when the spacer is thermally expanded and contracted. Development of a suitable spacer has been desired.

  The present invention has been made in view of such problems, and an object thereof is to provide a plastic optical fiber cable spacer (hereinafter simply referred to as a spacer) having a linear expansion coefficient close to that of POF.

In order to achieve the above object, the present invention includes a tensile body disposed in the center, and a spacer body formed of a thermoplastic resin and having a plurality of optical fiber housing grooves extending along the longitudinal direction on the outer periphery. In the plastic optical fiber cable spacer, the spacer has an inflection point in a load-elongation curve, and the inflection point exists in a range of allowable elongation of the plastic optical fiber in a cabled state, The tensile elastic modulus calculated from the cross-sectional area of the tensile body is smaller than the portion exceeding the inflection point until reaching the inflection point, and the coefficient of thermal expansion of the spacer is 1 × 10 ^{−5 to} 7 × 10 ⁻⁵ (1 / ° C.).

  In general, a material having a large coefficient of thermal expansion in an organic material has low tensile performance, and when this is used as a tensile strength body, the cross-sectional area must be increased in order to satisfy the required performance. Under such conditions, as a result, the outer diameter of the spacer becomes thick, which is not preferable.

  Therefore, the present inventors have a low tensile elastic modulus in the range of the allowable elongation of POF, that is, in the region where the elongation is within 0.02 to 0.5%, but the coefficient of thermal expansion is large. In the range exceeding the allowable elongation, that is, in the region where the elongation exceeds 0.5%, a spacer having a large tensile elastic modulus has been developed.

  According to the spacer having such properties, the thermal linear expansion coefficient can be approximated to that of POF, and tensile performance can be ensured without increasing the diameter of the spacer.

When the thermal linear expansion coefficient is lower than the lower limit, that is, 1 × 10 ⁻⁵ , there is a problem that the thermal expansion of POF cannot be followed, and when the upper limit of 7 × 10 ⁻⁵ is exceeded, strain in the tensile direction is added to POF. There is a problem that.

  In the present invention, the tensile elastic modulus until the elongation in the load-elongation curve reaches the inflection point is smaller than the portion where the elongation exceeds the inflection point. In a range where the load acting on the cable is small (substantially corresponding to the use range), the spacer is allowed to increase in elongation.

  That is, an area where strength is weak is provided. However, for example, when a large load acts on the cable due to an unexpected accident or the like, it is expected that the allowable elongation of POF will be exceeded.

  In the present invention, in order to deal with such a case, after the inflection point, the tensile elastic modulus is increased so that the POF carried on the spacer does not expand even in the case of an accident.

  Moreover, in this invention, the said inflection point can be set so that it may exist in the elongation range of 0.02-0.5%. In this case, if the elongation at the inflection point is below the lower limit value, there is a problem that the expansion and contraction of the POF cannot be followed. If the upper limit value is exceeded, an external force is directly applied to the POF. There is a problem that it cannot be protected effectively.

  In the present invention, the tensile modulus calculated from the cross-sectional area of the tensile body until the elongation reaches the inflection point is 63700 to 127400 MPa, and the elongation exceeds the inflection point. The tensile elastic modulus calculated from the cross-sectional area of the tensile strength body at can be set to exceed 127400 MPa.

  In this case, if the tensile elastic modulus is less than 63700 MPa, the cross-sectional area of the tensile body must be increased to effectively protect the optical fiber against the tensile force acting on the cable, resulting in the large diameter of the cable. This is not preferable.

  The tensile body is composed of a continuous reinforcing fiber made of polyparaphenylene benzobisoxazole fiber and a fiber reinforced synthetic resin rod made of a synthetic resin matrix. The outer periphery of the tensile body is made by extrusion molding of a thermoplastic resin. A pre-coating layer formed, and a spacer main body formed by extruding a thermoplastic resin on the outer periphery of the pre-coating layer to form a plurality of optical fiber housing grooves extending along the longitudinal direction. When the cross-sectional area of the preliminary coating layer is S1 and the cross-sectional area of the tensile body is S2, the ratio of S1 and S2 (S1 / S2) can be 3 or more.

  According to this configuration, FRP using polyparaphenylene benzobisoxazole fibers as continuous reinforcing fibers has a low compressive elastic modulus, and is melt coated with a material having a large coefficient of thermal expansion such as polyethylene around the preliminary coating layer or When the spacer body coating is provided, the phenomenon that the FRP contracts due to the thermal contraction of the coating resin appears. When the FRP contracts, the thermal expansion coefficient of the coated resin becomes dominant, and as a result, suitable for POF cables. A spacer is obtained.

  When the ratio of S1 and S2 (S1 / S2) is less than 3, the FRP characteristics are dominant and the POF cannot be effectively protected.

  As described above in detail, the plastic optical fiber cable spacer according to the present invention has a linear expansion coefficient close to that of POF.

  Hereinafter, preferred embodiments of the present invention will be described in detail. FIG. 1 shows an embodiment of a plastic optical fiber cable spacer according to the present invention. The spacer 10 shown in the figure has a tensile body 12 disposed in the center, and a plurality of optical fiber housing grooves 14 and ribs 15 formed by extrusion molding of a thermoplastic resin on the outer periphery of the tensile body and extending along the longitudinal direction. And a spacer main body 16 provided with.

  The tensile body 12 is made of, for example, FRP in which polyparaphenylene benzobisoxazole fibers are preferably used as continuous reinforcing fibers, and these fibers are integrally bound with a matrix made of a cured product of a thermosetting resin.

  In the example shown in FIG. 1, a thermoplastic resin preliminary coating layer 22 is provided on the outer periphery of the tensile body 12, and this preliminary coating layer 22 is uncured heat before becoming the tensile body 12 or the tensile body. A primary coating layer 18 obtained by extruding a thermoplastic resin into a rod-shaped article of continuous reinforcing fibers impregnated with a curable resin, and a secondary coating layer 20 formed to have a predetermined outer diameter in order to increase the accuracy of the groove shape. Formed from.

However, in the case of a spacer having a small number of cores and a thin outer diameter, the secondary coating layer 20 is not necessary, and the preliminary coating layer 22 composed only of the primary coating layer 18 may be used.
The thermosetting resin impregnated in the reinforcing fiber is preferably cured under pressure at a temperature near the softening point of the thermoplastic resin forming the primary coating layer after the primary coating layer 18 is formed.

  As shown in FIG. 2, the spacer 10 of the present embodiment has a tensile elasticity calculated from the cross-sectional area of the strength member 12 in the region where the elongation is within 0.02 to 0.5% in the load-elongation curve. From the modulus (63700 to 127400 MPa), the tensile modulus (greater than 127400 MPa) calculated from the cross-sectional area of the strength member 12 in the region where the elongation exceeds it is larger.

  In other words, in the spacer 10 of the present embodiment, the inflection point A is within the upper limit of 0.5% of the elongation range, and the cross-sectional area of the strength member 12 in the region before the inflection point A is present. From the tensile elastic modulus (63700 to 127400 MPa) calculated from the above, the tensile elastic modulus (exceeding 127400 MPa) calculated from the cross-sectional area of the strength member 12 in the region beyond the inflection point A is larger.

  Here, the elongation of 0.02 to 0.5% is within the range of 0.01 to 1.0% of the allowable elongation in POF. The POF optical fiber within the allowable elongation is an elongation range in which the plastic optical fiber cable has no loss fluctuation.

  The thermoplastic resin, which is the material for the pre-coating layer and spacer, has low-temperature brittleness, and so on, and therefore, high-density, medium-density, low-density polyethylene, polypropylene, and other polyolefin-based single resins and various copolymers thereof Are selected from various resins according to the mechanical properties and heat resistance required for plastic optical fiber cables, and examples include polycarbonate resin and polybutylene terephthalate resin. it can.

  In one aspect of the present invention, a continuous reinforcing fiber is moderately tensioned and impregnated with an uncured thermosetting resin, drawn to a predetermined diameter, and then the outer periphery thereof is annularly formed with a molten thermoplastic resin. Pre-coating and immediately cooling and solidifying the pre-coating thermoplastic resin, and then heat-curing by introducing it into a high-pressure steam heat curing tank, so that the inner periphery of the pre-coating layer and the outer periphery of the FRP layer are in fluid contact under pressure. As a result, FRP as a tensile strength body after curing and the preliminary coating layer are anchor-bonded. Therefore, the FRP and the preliminary coating layer integrally behave such as thermal expansion and thermal contraction.

  In this case, the thermal expansion coefficient differs greatly between the preliminary coating layer made of thermoplastic resin and the cured FRP, and that of the preliminary coating layer is one digit or more larger. Therefore, the thermal expansion coefficient of the entire spacer can be adjusted by changing the thickness of each preliminary coating layer to one layer or a plurality of layers on the outer periphery of the tensile body and appropriately changing the thickness of each layer. By selecting as appropriate, a pre-coated tensile member that can follow the thermal expansion and contraction behavior of the plastic optical fiber can be obtained.

  In the present invention, when providing a plurality of preliminary coating layers of thermoplastic resin, the resin between the layers is selected from those having compatibility with each other, and generally the same resin is used, and the coating layers are separated when coating the outer layer. It is melt bonded and similarly coated with a spacer body.

  Therefore, in the spacer of the present invention, the tensile strength member, the preliminary coating layer thereof, and the spacer main body coating provided on the outer periphery thereof are bonded (heat fusion) to such an extent that thermal expansion and contraction can be at least integrated, and the inflection point is Since the tensile modulus is low before and the tensile modulus is high after the inflection point, it is possible to effectively protect and carry the plastic optical fiber as a whole spacer by adding to the thermal behavior of the plastic optical fiber.

  In the present invention, the load-elongation curve was obtained by using “Instron universal testing machine, Model: TCM-5000C” manufactured by Minebea, at a tensile speed of 5 mm / min and a chart feed speed of 50 mm / min. The tensile modulus was determined from the slope of this load-elongation curve.

Moreover, the measurement of the thermal linear expansion coefficient was measured by Shimadzu Corporation TMA-40.
Hereinafter, more specific examples of the present invention will be described together with comparative examples.

  Uses 26 texes of polyparaphenylene benzobisoxazole fiber (PBO fiber, manufactured by Toyobo Co., Ltd., trade name ZYLON) as a continuous reinforcing fiber, and vinyl containing a peroxide catalyst as a thermosetting resin. An uncured vinyl ester resin-containing fiber rod was manufactured by impregnating an ester resin (trade name Esther H-8100, manufactured by Mitsui Chemicals, Inc.) and drawing it with a nozzle having an inner diameter of φ2.0 mm.

  Subsequently, the fiber rod is led to the head portion of the melt extruder, and a linear low density polyethylene (LLDPE) (trade name NUCG5350, manufactured by Nihon Unicar Co., Ltd.) for forming a primary coating layer on the outer periphery of the fiber rod is die-molded. It was extruded into a more annular shape and coated (18) with an outer diameter of φ3.0 mm, which was immediately cooled to obtain a rod-like intermediate product in which the vinyl ester resin was uncured.

  Next, the intermediate product is guided to a heat curing tank having a length of 6 m filled with high-pressure steam at 145 ° C. at a take-off speed of 5 m / min, and after curing the vinyl ester resin, it is guided to the head portion of the melt extruder, LLDPE (trade name Neozex 2015M manufactured by Mitsui Chemicals Co., Ltd.) is extruded and secondary coated (20), and a pre-coated outer diameter φ7.4 mm and FRP diameter φ2.0 mm cross-section coated tensile strength wire (strength body) 12 having a preliminary coating layer 22 formed on the outer periphery thereof.

At this time, the cross-sectional area S1 of the ^two pre-coating layers 22 of 18 and 20 is 12.69πmm ² , the cross-sectional area S2 of the tensile body 12 is 1πmm ² , and the ratio S1 / S2 thereof is 12.69. Met.

  Further, the coated tensile strength wire is preheated to 60 ° C. and introduced into a rotating die corresponding to the cross-sectional shape of the spacer 10 to be manufactured, and high density polyethylene (HDPE) (Japan) is used as a resin for forming the spacer body 16. Polyolefin Co., Ltd., trade name J-Rex KKZ51C) was rotationally extrusion coated in the vertical direction, and then inserted into a stainless steel pipe having an inner diameter of 75 mm and a length of 1 m, while a surfactant (Matsumoto Yushi Co., Ltd., A spacer 10 having a diameter of 12.5 mm was obtained by introducing hot water having a temperature of 40 ° C. added with a trade name of Marpon FL-30) to a concentration of 0.1% from below and cooling by overflowing from above.

  The obtained spacer 10 has eight substantially U-shaped storage grooves 14 with a groove depth of 2.3 mm and a groove width of 2.75 mm, and these grooves 14 are reversed at a reversal pitch of 200 mm. It had a helical structure twisted in an SZ shape at an angle of 275 °, had a target dimensional shape, and satisfied various specifications.

  When the tensile performance of the spacer 10 was confirmed, the tensile elastic modulus calculated from the cross-sectional area of the tensile body 12 in the region where the elongation was up to 0.11% was 100940 MPa, and the elongation strain was 0.11%. The tensile elastic modulus in the exceeding region was 134260 MPa.

  That is, in the case of Example 1, the inflection point exists at an elongation of 0.11%, and the tensile modulus calculated from the cross-sectional area of the tensile body 12 is 100940 MPa in the previous region. The tensile modulus calculated from the cross-sectional area of the tensile body 12 in the region where the elongation of 0.11%, which is the inflection point, exceeded 134260 MPa.

Further, when the coefficient of thermal expansion of the spacer 10 of Example 1 was measured, it was 1.3 × 10 ⁻⁵ (1 / ° C.), which was a value approximated to that of POF.

  Uses 26 polyparaphenylene benzobisoxazole fibers (PBO fiber, manufactured by Toyobo Co., Ltd., trade name ZYLON) as continuous reinforcing fibers, and a vinyl ester resin containing a peroxide catalyst as a thermosetting resin. (Mitsui Chemicals Co., Ltd., trade name Esther H-8100) was impregnated and drawn with a nozzle having an inner diameter of 2.0 mm, then led to the head of the melt extruder, and the primary coating layer on the outer periphery LLDPE (made by Nihon Unicar Co., Ltd., trade name NUCG5350) is extruded from a die in a ring shape, coated to an outer diameter of 3.0 mm, cooled immediately, and the vinyl ester resin is uncured in a rod shape Intermediate product was obtained.

  Next, the intermediate product is guided to a heat curing tank having a length of 6 m filled with high-pressure steam at 145 ° C. at a take-off speed of 5 m / min, and after curing the vinyl ester resin, it is guided to the head portion of the melt extruder, LLDPE (trade name Neozex 2015M, manufactured by Mitsui Chemicals Co., Ltd.) is extruded and secondarily coated, and the coated outer tensile wire (outer circumference of the tensile body 12 ′) having a substantially circular cross section with a coated outer diameter of 11.6 mm and an FRP diameter of 2.0 mm To form a primary coating layer 18 ′ and a secondary coating layer 20 ′).

  The spacer of Example 2 is different in cross-sectional shape, number of grooves, and dimensions of each part as shown in FIG. 1, but the configuration is the same. To do.

At this time, the cross-sectional area S1 ′ of the two-layer preliminary coating layer 22 ′ is 32.64πmm ² , the cross-sectional area S2 ′ of the tensile body 12 ′ is 1πmm ² , and the ratio S1 ′ / S2 ′ is 32 .64.

  Further, this coated tensile strength wire is preheated to 60 ° C. and introduced into a rotating die corresponding to the cross-sectional shape of the spacer 10 ′ to be manufactured, and HDPE (Nippon Polyolefin Co., Ltd.) is used as a resin for forming the spacer body 16 ′. ), Product name: J-Rex KKZ51C) was coated by rotary extrusion as described above, and then inserted into a stainless steel pipe with an inner diameter of 75 mm and a length of 1 m, and a surfactant (made by Matsumoto Yushi Co., Ltd., product name Marpon FL). Hot water having a temperature of 40 ° C. added with −30) to a concentration of 0.1% was introduced from below, and was cooled by overflowing from above to obtain a spacer 10 ′ having a diameter of 16.4 mm.

  The obtained spacer 10 ′ has 15 substantially U-shaped storage grooves 14 ′ having a groove depth of 2.2 mm and a groove width of 2.7 mm, and these grooves 14 ′ have an inversion pitch of 350 mm. Thus, it has a spiral structure twisted in an SZ shape at an inversion angle of 275 °, has a target dimensional shape, and satisfies various specifications.

  When the load-elongation curve is confirmed by the tensile test of the spacer 10 ', an inflection point exists at an elongation of 0.35%, and the inflection point is calculated from the cross-sectional area of the tensile body 12'. The tensile elastic modulus was 88200 MPa, and the tensile elastic modulus in the region where the elongation exceeded 0.35% was 142100 MPa.

  That is, in the case of the second embodiment, 0.35% existing in the region where the elongation is within 0.02 to 0.5% is taken as the inflection point, and the tensile strength body 12 'in the region before that is Tensile modulus (142100 MPa) calculated from the cross-sectional area of the tensile body 12 ′ in a region where the elongation exceeds 0.35%, which is the inflection point, than the tensile modulus (88200 MPa) calculated from the cross-sectional area Is getting bigger.

In addition, the spacer 10 ′ of Example 1 was measured for the coefficient of thermal expansion,
The value is 2.5 × 10 ⁻⁵ (1 / ° C.), which is a value approximate to that of POF.

Comparative Example 1

  Spacers were obtained in the same manner as in Example 1 except that 16 aramid fibers of 1420 denier (1576 dTex) were used as the continuous reinforcing fibers. When a load-elongation curve was obtained by a tensile test of this PE spacer, there was no inflection point, and the tensile elastic modulus was 66640 MPa constant regardless of the elongation.

The spacer of Comparative Example 1 was measured for the coefficient of thermal expansion. The value was 1.5 × 10 ⁻⁷ (1 / ° C.), which was about 1/100 of that of POF.

Comparative Example 2

  A spacer was obtained in the same manner as in Example 1 except that 17 glass fibers of 280 dTex were used as the continuous reinforcing fiber. In the load-elongation curve by the tensile test of this spacer, the tensile elastic modulus was constant and 44100 MPa regardless of the elongation.

Further, the spacer of the present Comparative Example 2 was measured for the coefficient of thermal expansion, and was 6.0 × 10 ⁻⁶ (1 / ° C.), which was about ½ of that of POF.

It is sectional drawing which shows one Example of the spacer for plastic optical fiber cables concerning this invention. It is explanatory drawing of the load-elongation curve by the tension test of the spacer for plastic optical fiber cables concerning Example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Spacer 12 Strength body 14 Storage groove 15 Rib 16 Spacer main body 18 Primary coating layer 20 Secondary coating layer 22 Preliminary coating layer

Claims (4)

In a plastic optical fiber cable spacer having a tensile body disposed in the center and a spacer body formed of a thermoplastic resin and having a plurality of optical fiber housing grooves extending along the longitudinal direction on the outer periphery,
The spacer has an inflection point in the load-elongation curve,
The inflection point exists in the range of allowable elongation of the plastic optical fiber in a cabled state,
The tensile modulus calculated from the cross-sectional area of the tensile strength body is smaller than the portion exceeding the inflection point until reaching the inflection point, and the thermal linear expansion coefficient of the spacer is 1 ×. A spacer for a plastic optical fiber cable, wherein the spacer is 10 ^{−5 to} 7 × 10 ⁻⁵ (1 / ° C.).   2. The plastic optical fiber cable spacer according to claim 1, wherein the inflection point has an elongation in a range of 0.02 to 0.5%.   The tensile modulus calculated from the cross-sectional area of the strength member until the elongation reaches the inflection point is 63700 to 127400 MPa, and the strength member in the region where the elongation exceeds the inflection point. The spacer for a plastic optical fiber cable according to claim 1 or 2, wherein the tensile elastic modulus calculated from the cross-sectional area of the spacer exceeds 127400 MPa. The tensile body is composed of a continuous reinforcing fiber made of polyparaphenylene benzobisoxazole fiber and a fiber reinforced synthetic resin rod made of a synthetic resin matrix,
A pre-coating layer formed by extrusion molding of a thermoplastic resin on the outer periphery of the tensile body, and a plurality of optical fiber housing grooves extending along the longitudinal direction by extruding the thermoplastic resin to the outer periphery of the pre-coating layer A spacer body formed with
The ratio of S1 and S2 (S1 / S2) is set to 3 or more when the cross-sectional area of the preliminary coating layer on the outer periphery of the tensile body is S1 and the cross-sectional area of the tensile body is S2. The plastic optical fiber cable spacer according to any one of claims 1 to 3, wherein

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