JP4242802B2 - Optical fiber cord - Google Patents

Description

  The present invention relates to an optical fiber cord having a structure in which an optical fiber is protectively coated with a reinforcing coating layer composed of a reinforcing fiber and a thermoplastic resin matrix for integrally bonding the reinforcing fiber.

  An optical fiber cord having a structure in which an optical fiber is protected with a reinforcing coating layer composed of a reinforcing fiber and a thermoplastic resin matrix to which the reinforcing fiber is bonded has an optical fiber cord diameter smaller than that of a conventional loose type structure. The cost can be reduced by reducing the amount of the tensile strength fiber used, and further improvement in convenience at the time of attaching the connecting connector is expected.

  The optical fiber cord having such a structure has advantages of superior flexibility and less increase in transmission loss due to microbending compared to the same tight fiber-reinforced thermosetting synthetic resin coating (FRP coating) type. .

  By the way, this type of optical fiber cord is stipulated to reduce fluctuations in transmission loss due to temperature changes on the assumption that it will be used in various environments. An optical fiber cord having a structure coated with a reinforcing coating layer composed of a fiber and a thermoplastic resin matrix to which the fiber is bonded has a tight structure, and thus has a problem that fluctuation in optical transmission loss due to heat cycle increases. It was.

  Therefore, in order to solve such a problem, the present applicant has developed an optical fiber cord having a new structure, and has proposed this in Patent Document 1. An optical fiber cord disclosed in Patent Document 1 includes an optical fiber strand disposed in the center, and a non-binding reinforcing fiber layer that is coated on the outer periphery of the optical fiber strand and vertically attached with a reinforcing fiber bundle. The non-reinforcing reinforcing fiber layer is coated on the outer periphery, and has a reinforcing covering layer in which reinforcing fibers are integrally bound with a thermoplastic resin.

According to the optical fiber cord configured as described above, the optical transmission loss due to the heat cycle can be reduced, but there is also a technical problem described below.
JP 2003-75693 A

  That is, since the optical fiber cord disclosed in Patent Document 1 has a structure in which a reinforcing coating layer composed of a reinforcing fiber and a thermoplastic resin matrix for binding the reinforcing fiber is provided, the optical fiber cord is included in the coating layer. There is a problem that the gap is small and the weight of the cable is increased as compared with, for example, a foamed polyethylene coating.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an optical fiber cord capable of reducing the weight.

In order to achieve the above object, the present invention comprises an optical fiber disposed in the center,
In the optical fiber cord including a coating layer formed on the outer periphery of the optical fiber, the coating layer includes a heat-adhesive composite filament and a circular shape that does not have heat-adhesiveness with the heat-adhesive composite filament. The heat-adhesive composite filament includes a mixed filament mixed with filaments having a cross-section, and the core portion has a sheath core structure having a melting point higher than that of the sheath portion, and the filament is the heat-adhesive composite filament The melting point is higher than that of the sheath portion, and is arranged in a multifilament state in which a plurality of bundles are bundled, and the coating layer is bonded to the outer periphery of the optical fiber strand with the mixed filament vertically. By melting the sheath of the conductive composite filament , it was formed by heat bonding.

According to the optical fiber cord having such a configuration, the coating layer is heat-adhesive composite filaments, and includes a mixed filament mix without Filament the heat adhesive composite filaments and heat-adhesive covering layer Is formed by thermally bonding the heat-adhesive composite filament with the mixed filament vertically attached to the outer periphery of the optical fiber. At this time, since the filament has a circular cross section, in the multifilament bundled in plural, there are many voids around each filament, and these voids are not completely filled even when the heat-adhesive resin is melted. As a result, voids are formed on the outer periphery of the filament that does not have thermal adhesiveness, and the overall weight can be reduced by the voids.

Further, the present invention provides an optical fiber cord comprising an optical fiber strand disposed in the center and a coating layer formed on the outer periphery of the optical fiber strand, wherein the coating layer is a heat-adhesive composite filament And a mixed filament mixed with the thermoadhesive composite filament and a filament having a circular cross section having no thermal adhesiveness, and the core portion has a higher melting point than the sheath portion. a sheath-core structure, the filament is a higher melting point than the sheath portion of the heat-adhesive composite filaments, are arranged in the form of multi-filament bundling a plurality, the covering layer, said optical fiber element The sheath of the thermoadhesive composite filament is melted in a state where the filament is densely arranged on the outer periphery of the wire and the mixed filament is vertically attached to the outer periphery of the filament. It is to, formed by thermal bonding.

  The thermoadhesive composite filament has a sheath-core structure, and the melting point of the sheath component can be lower by 20 ° C. or more than the melting points of the core component and the filament.

  In the heat-adhesive composite filament, the sheath component is high-density polyethylene, the core component is made of isotactic polypropylene, and the filament is made of a single component of isotactic polypropylene.

  The sheath-core ratio of the heat-adhesive composite filament can be set such that the sheath: core ratio is within the range of 3: 7 to 7: 3.

  The blending ratio of the heat-adhesive composite filament and the heat-adhesive composite filament and the filament not having thermal adhesiveness is a cross-sectional area ratio, and the ratio of the filament having no thermal adhesiveness is in the range of 5 to 50%. Can be set within.

  One or both of the heat-adhesive composite filament and the heat-adhesive composite filament and the filament not having heat-adhesiveness can be crimped.

  According to the optical fiber cord of the present invention, the coating layer includes a heat-adhesive composite filament, and a mixed filament in which the heat-adhesive composite filament and a filament not having heat adhesive properties are mixed. Since the heat-adhesive composite filament is thermally bonded in a state where it is vertically attached to the outer periphery of the optical fiber, a void is formed on the outer periphery of the filament not having the heat-adhesive property, and the overall weight can be reduced by the amount of the void. .

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

  FIG. 1 shows a first embodiment of an optical fiber cord according to the present invention. The optical fiber cord 10 shown in the figure includes an optical fiber strand 12 disposed in the center and a coating layer 14.

  The coating layer 14 includes a heat-adhesive composite filament 16 and a mixed filament in which the heat-adhesive composite filament 16 and a filament 18 that does not have thermal adhesiveness are mixed. In a state of being vertically attached to the outer periphery, the heat-adhesive composite filament 16 is thermally bonded to form an annular shape having a predetermined thickness.

  The optical fiber 12 is illustrated as a single core in FIG. 1, but may be a tape core having a plurality of cores, or a plurality of stacked tape cores. The heat-adhesive composite filament 16 can be composed of a composite fiber having a sheath core structure having a high melting point component and a low melting point component, for example.

  In this case, the heat-adhesive composite filament 16 has a reinforcing fiber 160 as a core part as a high melting point component and a sheath part as a low melting point component, and a thermoplastic resin matrix 161 or an adhesive intersection. In this case, the sheath is selected to have a melting point that is 20 ° C. lower than the melting points of the reinforcing fiber 160 serving as the core and the filament 18 having no adhesiveness.

  In FIG. 1, the white portion of the coating layer 14 is a portion of the heat-adhesive composite filament 16 shown partially enlarged in the drawing, and this portion is also shown in the enlarged view. There are voids.

  In the case of the present embodiment, as the heat-adhesive composite filament 16, a composite fiber having a sheath-core structure in which the sheath component is high-density polyethylene and the core component is isotactic polypropylene can be suitably employed.

  In this case, the thermoadhesive composite filament 16 and the filament 18 having no thermal adhesiveness can be composed of a single component of isotactic polypropylene. When such a combination is adopted, the porosity is high, It is possible to make a very lightweight optical fiber cord.

  In addition, in the example shown in FIG. 1, the filament 18 is comprised from the multifilament which bundled multiple pieces. In the case of a composite fiber having a sheath core structure in which the sheath component is high-density polyethylene and the core component is isotactic polypropylene, the sheath-core ratio is sufficient when the sheath component ratio is less than 3/10. Therefore, FRTP conversion becomes insufficient, and if the ratio of the core component is less than 3/10, a sufficient reinforcing effect cannot be obtained, so the range of 3: 7 to 7: 3 is preferable.

  Further, when tensile strength is required, the filament 18 may be mixed with reinforcing fibers having high strength and high elastic modulus such as aramid fiber, glass fiber, and polyester fiber.

  The heat-adhesive composite filament 16 and the filament 18 not having heat-adhesion are vertically mixed with the outer periphery of the optical fiber 10 in a mixed filament state, and thereafter, a thermoplastic resin matrix having a low melting point component. 161 is melted to integrally bind the reinforcing fibers 160 having a high melting point component.

  The mixing means in this case may be a known interfacing method in addition to a method of arranging multi-filament bundles divided into small deniers when they are vertically attached to the outer periphery of the optical fiber 10 and mixing them at the time of assembly. It is also possible to use a mixed filament produced by the Mingle (Comingle) method.

  FIG. 3 is a schematic diagram of an example in which mixed filaments are produced by the intermingle method. In the mixed filaments shown in FIG. 3, a single filament 18 is randomly formed on a part of the thermoadhesive composite filament 16. It is also possible to form the coating layer 14 shown in FIG. 1 with such a mixed filament.

  As the heat-adhesive composite filament 16 constituting the mixed filament and the filament 18 having no heat-adhesiveness, at least one of them or both of them can be used which has crimps. There is no limitation on the method of imparting crimp.

  When the filaments 16 and 18 are crimped, the entanglement between the filaments 16 and 18 is increased, or when the fibers 16 are converged to form the optical fiber coating layer 14, the voids are easily formed by the repulsion. Effects such as can be obtained.

  A preferable blending ratio of the heat-adhesive composite filament 16 and the filament 18 having no heat-adhesiveness is a cross-sectional area ratio, and the filament 18 is 5% or more and 50% or less. In this case, if it is less than 5%, sufficient light weight effect cannot be obtained, and if it exceeds 50%, FRTP conversion becomes insufficient.

  If further weight reduction is desired, hollow filaments can be used for either one or both of the thermoadhesive composite filament 16 and the filament 18 having no thermal adhesiveness.

  In this case, the hollow filament is selected from, for example, those having a donut cross-section or lotus-like or rice-shaped voids, and the hollow fiber is polyethylene homopolymer, polypropylene, or various co-components mainly composed of these. Polymers, various modified resins, various fluororesins, and the like can be used.

  According to the optical fiber cord 10 configured as described above, the coating layer 14 is a mixture in which the heat-adhesive composite filament 16 and the heat-adhesive composite filament 16 and the filament 18 not having heat adhesiveness are mixed. The filament 14 and the coating layer 14 are formed by thermally bonding the heat-adhesive composite filament 16 with the mixed filament vertically attached to the outer periphery of the optical fiber 12. A void is formed on the outer periphery, and the overall weight can be reduced by the amount of the void.

  FIG. 2 shows a second embodiment of the optical fiber cord according to the present invention, and the same or corresponding parts as those in the above embodiment are denoted by the same reference numerals. The optical fiber cord 10a shown in the figure includes an optical fiber strand 12a disposed in the center and a coating layer 14.

  The coating layer 14a includes a heat-adhesive composite filament 16a and a mixed filament in which the heat-adhesive composite filament 16a and a filament 18a that does not have heat adhesive properties are mixed, and the mixed filament is used as the optical fiber strand 12a. In a state of being vertically attached to the outer periphery, the thermoadhesive composite filament 16a is thermally bonded to form an annular shape having a predetermined thickness.

  In the case of the present embodiment, in the coating layer 14a, the filaments 18a are densely arranged on the outer periphery of the optical fiber 12a, and the thermoadhesive composite filament 16a is arranged on the outer periphery thereof.

  In this case, the heat-adhesive composite filament 16a has a reinforcing fiber 160a serving as a core part as a high melting point component and a thermoplastic resin matrix 161a serving as a sheath part as a low melting point component. The matrix 161a is a reinforcing fiber serving as a core part. Those having a melting point of 20 ° C. or more lower than the melting points of 160a and the filament 18a having no thermal adhesiveness are selected.

  If the thickness of the outer layer portion formed of the heat-adhesive composite filament 16a is 0.2 mm or less, the strength of the FRTP portion becomes insufficient. Further, in the case of the present embodiment, for example, when moisture intrusion into the optical fiber cord 10a is predicted, it is desirable to mix water-absorbing fibers in a portion where the filaments 18a are densely arranged.

In the second embodiment configured as described above, in addition to the effects of the first embodiment, the dense filament 18a provided on the outer periphery of the optical fiber strand 12a serves as an appropriate cushion, and the optical fiber strand 12a is bent or impacted. Can be effectively protected from.
Hereinafter, more specific examples of the present invention will be described together with comparative examples.

Example 1

  Around the φ0.25 mm UV optical fiber 12, the core component is isotactic polypropylene having a melting point of 163 ° C., the sheath component is high-density polyethylene having a melting point of 131 ° C., and the cross-sectional area ratio between the core and the sheath is 1. 1 and 8 conjugated fibers with a fineness of 444 dtex (60 filaments, single yarn diameter 32 μm) (heat-adhesive composite filament 16), isotactic polypropylene fibers with a fineness of 222 dtex and a melting point of 163 ° C. (number of filaments) 150 ° C., which is the temperature at which only the sheath component melts after being longitudinally attached as a mixed filament in which 5 pieces (60 pieces, single yarn diameter: 24 μm) (thermal adhesive composite filament 16 and filament 18 having no adhesiveness) are mixed. Introduced into a thermoformed nozzle with an inner diameter of φ0.9 mm, which is temperature-controlled, and continuously taken out at 30 m / min. A 0.89 mm fiber-reinforced thermoplastic resin-coated optical cord 10 was obtained.

  The ratio of the voids in the cross-sectional area of the fiber-reinforced thermoplastic coating portion of the obtained fiber-reinforced thermoplastic resin-coated optical cord 10 was calculated by measuring the apparent specific gravity using a specific gravity bottle and found to be 12.5%.

  The fiber-reinforced thermoplastic resin-coated optical cord 10 was confirmed to be able to take out an optical fiber. The fiber-reinforced thermoplastic resin coating layer 14 and the optical fiber 12 were not adhered, and the take-out property was good. .

  Further, the optical fiber 12 is not decentered and is located at the center of the coating layer 14, and the position of the optical fiber 12 is not shifted even if it is bent. The optical transmission performance was also good at 0.35 dB / km.

Example 2

  An isotactic polypropylene fiber having a fineness of 55 dtex and a melting point of 163 ° C. around the Φ0.25 mm UV optical fiber 12a (multifilament, 15 filaments, single filament diameter 22 μm) (adhesiveness to the thermoadhesive composite filament 16a) The filaments 18a) which do not have are vertically attached, the core component is isotactic polypropylene having a melting point of 163 ° C., the sheath component is high-density polyethylene having a melting point of 131 ° C., and the cross-sectional area ratio between the core portion and the sheath portion is Conjugate fiber (multifilament, 60 filaments, single filament diameter 32 μm) (thermoadhesive composite filament 16a) with 1: 1 and fineness of 444 dtex, isotactic polypropylene with fineness of 222 dtex and melting point of 163 ° C. Fiber (60 filaments, single yarn diameter 24μm) (thermal bonding An inner diameter φ0... Is adjusted to 150 ° C., which is a temperature at which only the sheath component melts. This was introduced into a 9 mm thermoforming nozzle and continuously taken at 30 m / min to obtain a fiber reinforced thermoplastic resin-coated optical cord 10a having an outer diameter of φ0.89 mm.

  The ratio of voids in the cross-sectional area of the fiber-reinforced thermoplastic coating layer 14a of the obtained fiber-reinforced thermoplastic resin-coated optical cord 10a was calculated by measuring the apparent specific gravity using a specific gravity bottle and found to be 9.5%. It was.

  When the fiber-reinforced thermoplastic resin-coated optical cord 10a was confirmed to be able to take out an optical fiber, the fiber-reinforced thermoplastic resin-coated layer 14a and the optical fiber 12a were not adhered, and the take-out property was good. .

  Further, the optical fiber 12a is not decentered and is located in the center of the coating layer 14a, and the position of the optical fiber 12a is not shifted even if it is bent. The optical transmission performance was also good at 0.30 dB / km.

Comparative Example 1

  Around the φ0.25 mm UV optical fiber 12, the core component is isotactic polypropylene having a melting point of 163 ° C., the sheath component is high-density polyethylene having a melting point of 131 ° C., and the cross-sectional area ratio between the core and the sheath is 1. The inner diameter was adjusted to 150 ° C., which is the temperature at which only the sheath component melts after 21 conjugate fibers (multifilament, 30 filaments, single filament diameter: 32 μm) with a fineness of 222 dtex are longitudinally attached. It was introduced into a thermoforming nozzle having a diameter of 0.9 mm and continuously taken out at 30 m / min to obtain a fiber-reinforced thermoplastic resin-coated optical cord having an outer diameter of 0.88 mm.

  The ratio of voids in the cross-sectional area of the fiber reinforced thermoplastic coating of the obtained optical cord was calculated by measuring the apparent specific gravity using a specific gravity bottle, which was 5.1%. The effect was small.

Comparative Example 2

  The fiber to be used is isotactic polypropylene whose core component is melting point 163 ° C., the sheath component is high density polyethylene having a melting point 131 ° C., the cross-sectional area ratio of the core portion and the sheath portion is 1: 1, and the fineness is 444 dtex. 5 conjugate fibers (multifilament, 60 filaments, single filament diameter 24 μm) and isotactic polypropylene fiber (multifilament, 60 filaments, single filament diameter 24 μm) with fineness of 222 dtex and melting point of 163 ° C. 11 A fiber reinforced thermoplastic resin-coated optical cord was obtained by a method substantially similar to that of Example 1 except that the optical fiber was used, but the optical fiber jumped out due to insufficient FRTP conversion.

  As described above in detail, according to the optical fiber cord according to the present invention, the weight can be reduced and the weight can be reduced. Therefore, in addition to the application to the conventional optical fiber cord, for example, a pre-laid plastic It can be effectively used for applications that require particularly light weight, such as components of pneumatic fiber cords that are fed into a tube line at a flow rate of air.

It is sectional drawing which shows 1st Example of the optical fiber cord concerning this invention. It is sectional drawing which shows 2nd Example of the optical fiber cord concerning this invention. It is a schematic diagram at the time of mixing a filament by the intermingle method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,10a Optical fiber cord 12,12a Optical fiber strand 14,14a Coating layer 16,16a Thermal adhesive composite filament 160,160a Reinforcing fiber 161,161a Thermoplastic resin matrix 18,18a Non-thermal adhesive filament

Claims (7)

An optical fiber disposed in the center;
In an optical fiber cord comprising a coating layer formed on the outer periphery of the optical fiber,
The coating layer includes a heat-adhesive composite filament, and a mixed filament in which the heat-adhesive composite filament and a filament having a circular cross section that does not have thermal adhesiveness are mixed,
The thermoadhesive composite filament has a sheath core structure in which the core has a higher melting point than the sheath,
The filament has a higher melting point than the sheath part of the thermoadhesive composite filament, and is arranged in a multifilament state in which a plurality of bundles are bundled,
The light is characterized in that the coating layer is formed by heat bonding by melting the sheath of the thermoadhesive composite filament in a state where the mixed filament is vertically attached to the outer periphery of the optical fiber. Fiber cord. An optical fiber disposed in the center;
In an optical fiber cord comprising a coating layer formed on the outer periphery of the optical fiber,
The coating layer includes a heat-adhesive composite filament, and a mixed filament in which the heat-adhesive composite filament and a filament having a circular cross section that does not have thermal adhesiveness are mixed,
The thermoadhesive composite filament has a sheath core structure in which the core has a higher melting point than the sheath,
The filament has a higher melting point than the sheath part of the thermoadhesive composite filament, and is arranged in a multifilament state in which a plurality of bundles are bundled,
By melting the sheath of the thermoadhesive composite filament in a state where the filament is densely arranged on the outer periphery of the optical fiber and the mixed filament is vertically attached to the outer periphery of the filament. An optical fiber cord formed by thermal bonding . The reinforcing according to claim 1 or 2, wherein the heat-adhesive composite filament has a sheath-core structure, and the melting point of the sheath component is 20 ° C or lower than the melting points of the core component and the filament. Fiber optic cord. The heat-adhesive composite filament has the sheath component made of high-density polyethylene and the core component made of isotactic polypropylene,
The optical fiber cord according to any one of claims 1 to 3, wherein the filament having no thermal adhesiveness is made of a single component of isotactic polypropylene. 5. The optical fiber cord according to claim 4, wherein the sheath-core ratio of the heat-adhesive composite filament is set such that a sheath: core ratio is within a range of 3: 7 to 7: 3. The blending ratio of the heat-adhesive composite filament and the heat-adhesive composite filament and the filament not having thermal adhesiveness is a cross-sectional area ratio, and the ratio of the filament having no thermal adhesiveness is in the range of 5 to 50%. The optical fiber cord according to any one of claims 1 to 5, wherein the optical fiber cord is set within the range. 7. The crimp according to claim 1, wherein the thermal adhesive composite filament and the thermal adhesive composite filament and the filament not having thermal adhesiveness are provided with crimps. Fiber optic cord.

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