JP5755916B2 - Multi-core plastic optical fiber and cable - Google Patents

Description

  The present invention relates to a plastic optical fiber.

  A plastic optical fiber has a structure in which a core fiber made of a transparent resin is surrounded by a sheath layer made of a resin having a lower refractive index than the transparent resin, and light is reflected at the boundary between the core and the sheath layer. A medium for transmitting an optical signal in the core. A plastic optical fiber is superior in flexibility to a quartz glass optical fiber, and a fiber having a large diameter that can be easily aligned during connection can be used.

  In the single-core plastic optical fiber, when the diameter of the core fiber is increased in order to increase the amount of light transmitted, the occurrence of light loss due to bending increases. In contrast, a multi-core plastic optical fiber reduces the diameter of each core fiber and suppresses the occurrence of the above optical loss, and then combines the light transmitted through each core fiber to increase the total amount of light. It has the advantage that it can be made larger. For this reason, in recent years, multi-core plastic optical fibers have been adopted for various applications.

  For example, each core fiber is surrounded by a transparent first sheath resin having a refractive index lower than that of the core resin, and the outside of the first sheath layer surrounding each core fiber is surrounded by the first sheath resin. A multi-core plastic optical fiber is proposed that is surrounded by a second sheath resin having a lower refractive index and is manufactured by a composite spinning method so that they are formed into a bundle of fibers (see, for example, Patent Document 1).

  Moreover, in order to protect more reliably from physical or chemical damage, a coating resin layer made of a thermoplastic resin is formed on the outer side of the multi-core plastic optical fiber to form a multi-core plastic optical fiber cable. Often used.

  One application of a plastic optical fiber is a light emitting decoration. The light-emitting decorative body makes light incident from one end of the optical fiber, and the incident light is transmitted through the optical fiber and emitted from the other end, thereby causing the end of the optical fiber to emit light.

WO1998 / 035247

  By the way, when the multi-core plastic optical fiber is used as a light emitting decoration, the multi-core plastic optical fiber on the light emitting end face side is easily assembled with individual core fibers and the first sheath layer (hereinafter referred to as “single”). It is also referred to as a “core plastic optical fiber.”) If it is solved one by one, a small light emitting decoration consisting of a small light emitting surface becomes possible. However, if the multi-core plastic optical fiber described in Patent Document 1 is used for light-emitting decoration, it is difficult to easily break the multi-core plastic optical fiber into individual single-core plastic optical fibers one by one. There's a problem.

  Therefore, the present invention can easily unravel each single-core plastic optical fiber one by one, and can provide a multi-core plastic optical fiber strand with good optical transmission of each single-core plastic optical fiber. The purpose is to provide.

  As a result of studying the above problems, the present inventor has found that a plurality of cores made of resin, a first sheath layer made of a first sheath resin surrounding the core, and an outer periphery of the first sheath layer are in contact with each other. In a multi-core plastic optical fiber wire including a second sheath layer made of a two-sheath resin, each single-core plastic light can be easily formed by forming the first sheath layer and the second sheath layer from a specific resin. Based on this finding, the present inventors have completed the present invention.

  That is, this invention is the following multi-core plastic optical fiber strands and cables.

[1]
A multi-core including a plurality of cores made of resin, a first sheath layer made of a first sheath resin surrounding the core, and a second sheath layer made of a second sheath resin in contact with the outer periphery of the first sheath layer A plastic optical fiber,
The first sheath resin is composed of a copolymer mainly composed of the following components (a) and (b):
The mass ratio ((b) / (b)) between the component (b) and the component (b) in the first sheath resin is 2 to 10,
The second sheath resin is made of a copolymer having the following units (A), (B) and (C) as the main component of the polymerization unit,
The mass ratio ((B) / (A)) of the unit (A) and the unit (B) in the copolymer of the second sheath resin is 1.4 to 1.7,
The mass ratio ((C) / (A)) of the unit (A) to the unit (C) in the copolymer of the second sheath resin is 0.75 to 0.95, and
A multicore plastic optical fiber in which the copolymer of the second sheath resin contains at least one of a carbonate group and a haloformyl group;
(A) a fluoroalkyl methacrylate represented by the following formula (i):
(In the formula (i), n is 1 or 2, m ₁ is 0 or an integer of 1 to 4, and X is a hydrogen atom or a fluorine atom)
(B) methyl methacrylate,
(A) ethylene units,
(B) tetrafluoroethylene unit,
(C) Hexafluoropropylene unit.

[2]
The multi-core plastic optical fiber according to [1], wherein the copolymer of the second sheath resin contains at least one of a carbonate group and a haloformyl group at an end thereof.

[3]
The multi-core plastic according to [1] or [2], wherein the copolymer of the second sheath resin contains 3-1000 at least one of a carbonate group and a haloformyl group per 1 × 10 ⁶ carbon atoms. Optical fiber strand.

[4]
The copolymer of the second sheath resin has a melting point in the range of 150 to 200 ° C., the refractive index measured at 20 ° C. with sodium D line is 1.37 to 1.41, and the melt flow rate (230 The multi-core plastic optical fiber according to any one of [1] to [3], wherein the temperature is 5 to 100 g / 10 min.

[5]
The multicore plastic according to any one of [1] to [4], wherein the copolymer of the second sheath resin has a Shore D hardness value (measured according to ASTM D2240) at 23 ° C. of 50 to 90. Optical fiber strand.

[6]
The multi-core plastic optical fiber according to any one of [1] to [5], wherein the resin constituting the core is a polymethyl methacrylate resin.

[7]
[1] to [6] the multi-core plastic optical fiber according to any one of
A multi-core plastic optical fiber cable having a coating layer containing a thermoplastic resin formed on the outside of the multi-core plastic optical fiber.

  Since the multi-core plastic optical fiber and cable of the present invention can be easily peeled at the interface between the first sheath layer and the second sheath layer, the bundle of the core fiber and the first sheath layer (single-core plastic) Optical fibers) can be used one by one. The multi-core plastic optical fiber of the present invention can be used by easily unwinding each single-core plastic optical fiber, and the optical transmission of each single-core plastic optical fiber is good. Therefore, it is most suitable for electric decoration use.

It is a schematic diagram which shows an example of the multi-core plastic optical fiber strand of this invention.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The following embodiment is an exemplification for explaining the present invention, and is not intended to limit the present invention only to this embodiment. And this invention can be deform | transformed suitably and implemented within the range of the summary.

≪Multi-core plastic optical fiber strand≫
The multi-core plastic optical fiber of the present embodiment includes a plurality of cores made of resin, a first sheath layer made of a first sheath resin surrounding the core, and an outer periphery of the first sheath layer. A multi-core plastic optical fiber including a second sheath layer made of a two-sheath resin, wherein the first sheath resin is made of a copolymer having the following components (A) and (B) as main components: The mass ratio ((b) / (b)) between the component (b) and the component (a) in the first sheath resin is 2 to 10, and the second sheath resin is the following unit (A) , (B) and (C) are the main components of the polymerized unit, and the mass ratio ((B) of the unit (A) to the unit (B) in the copolymer of the second sheath resin. / (A)) is 1.4 to 1.7, and the mass ratio ((C) / (A)) of the unit (A) to the unit (C) in the copolymer of the second sheath resin is 0.75 0.95, and a copolymer of the second sheath resin contains at least one carbonate group and haloformyl group.
(A) a fluoroalkyl methacrylate represented by the following formula (i):
(In the formula (i), n is 1 or 2, m ₁ is 0 or an integer of 1 to 4, and X is a hydrogen atom or a fluorine atom)
(B) methyl methacrylate,
(A) ethylene units,
(B) tetrafluoroethylene unit,
(C) Hexafluoropropylene unit.

  In the present embodiment, the multi-core plastic optical fiber has a plurality of bundles (single-core plastic optical fibers) surrounding the core with a first sheath layer made of a first sheath resin. A structure in which one sheath layer is surrounded so as to be in direct contact with a second sheath layer made of a second sheath resin.

  As the multi-core plastic optical fiber of the present embodiment, specifically, a group of individual cores 1 and a first sheath layer 2 surrounding the core 1 as shown in FIG. Is preferably a multi-core plastic optical fiber 10 having a structure in which the sea 3 is formed by fusion with each other (hereinafter referred to as a sea-island structure).

  In the present embodiment, the multi-core plastic optical fiber cable refers to one having a structure in which a coating layer is provided outside the multi-core plastic optical fiber.

<Core resin>
The resin constituting the core (hereinafter also referred to as “core resin”) is not particularly limited, but is preferably a resin having as high a transmissivity as possible, for example, a polymethyl methacrylate resin. The polymethyl methacrylate resin refers to a homopolymer of methyl methacrylate or a copolymer containing 50% by mass or more of a methyl methacrylate component. Examples of components copolymerizable with the methyl methacrylate component include acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate, methacrylate esters such as ethyl methacrylate, propyl methacrylate, and cyclohexyl methacrylate, and isopropyl maleimide. Such as maleimides, acrylic acid, methacrylic acid, styrene and the like, and one or more of these may be appropriately selected and copolymerized. The molecular weight of the polymethyl methacrylate resin is preferably about 80,000 to 200,000 as the weight average molecular weight from the viewpoint of fluidity, and is preferably 100,000 to 120,000. The core resin may contain an additive or the like as long as the transparency is not impaired.

<First sheath resin>
1st sheath resin consists of a copolymer obtained by copolymerizing the raw material component containing the specific (ii) fluoroalkylmethacrylate mentioned later and (ro) methylmethacrylate.

  Component (I) is a fluoroalkyl methacrylate represented by the following formula (i).

In formula (i), n is 1 or 2, m ₁ is 0 or an integer of 1 to 4, and X is a hydrogen atom or a fluorine atom. m ₁ is preferably 0 or an integer of 1 to 3, and m ₁ is particularly preferably an integer of 1 or 2. When m ₁ is in the above range, the interface state between the first sheath layer and the second sheath layer is less disturbed especially when the multi-core plastic optical fiber is unwound, and the interface state is more suitable for unraveling by hand. preferable.

  In the first sheath resin, the mass ratio ((b) / (b)) between the component (b) and the component (b) is 2 or more, more preferably 3 or more, and still more preferably 3.5 or more. It is. Further, the mass ratio ((ii) / (ii)) between the component (b) and the component (a) is 10 or less, more preferably 8 or less, still more preferably 6 or less, and particularly preferably 5 or less. is there.

  In the first sheath resin, the first sheath layer and the second sheath layer when the multi-core plastic optical fiber is unwound when the blending amount of the component (A) and the component (B) is within the above range. The interface state is less disturbed and the interface state is more suitable for solving by hand.

  In addition to component (a) and component (b), monomers copolymerizable therewith may be copolymerized and included in the first sheath resin. Examples of the copolymerizable monomer include fluoroalkyl acrylate, alkyl methacrylate, alkyl acrylate, methacrylic acid, acrylic acid, and the like other than component (a) and component (b). More specifically, examples of the fluoroalkyl acrylate include trifluoroethyl acrylate, tetrafluoropropyl acrylate, and octafluoropentyl acrylate, examples of the alkyl methacrylate include ethyl methacrylate, and examples of the alkyl acrylate include methyl acrylate. And acrylate monomers such as ethyl acrylate and butyl acrylate.

  The first sheath resin is made of a copolymer mainly composed of component (a) and component (b). Here, “main component” means that the amount of components other than the component (A) and the component (B) is relatively small. Specifically, the total content of the component (I) and the component (B) in the copolymer constituting the first sheath resin is preferably 75% by mass or more, more preferably 80% by mass. Above, more preferably 85% by mass or more, particularly preferably 90% by mass or more, but other monomers copolymerizable with Component (A) and Component (B) as long as the effects of the present invention are not impaired. May be copolymerized.

<Second sheath resin>
The second sheath resin is a copolymer having (A) an ethylene unit, (B) a tetrafluoroethylene unit, and (C) a hexafluoropropylene unit as main components of the polymerization unit, and the copolymer A copolymer containing at least one of a carbonate group and a haloformyl group is used. In addition, also when it contains at least one of a carbonate group and a haloformyl group only in the terminal of a copolymer, it shall be included in the copolymer which contains at least one of a carbonate group and a haloformyl group in a copolymer. Moreover, the case where it has both a carbonate group and a haloformyl group is included with at least one of a carbonate group and a haloformyl group.

  Here, “main component” means that the amount of components other than the units (A) to (C) is relatively small, and (A) in the copolymer constituting the second sheath resin. The total content of ethylene units, (B) tetrafluoroethylene units and (C) hexafluoropropylene units is preferably 70% by mass or more. The total content of the units (A) to (C) in the copolymer is more preferably 80% by mass or more, still more preferably 85% by mass or more, and particularly preferably 90% by mass or more. As long as the above is not impaired, the units (A) to (C) may be copolymerized with other monomers copolymerizable with the units (A) to (C). Examples of other monomers copolymerizable with the units (A) to (C) include hexafluoroisobutene, propylene, 1-butene, 2-butene, vinyl chloride, vinylidene chloride, vinylidene fluoride, and chlorotrifluoro Examples thereof include olefins such as ethylene, vinyl fluoride, hexafluoroisobutene, and perfluoro (alkyl vinyl ether).

  Furthermore, in this Embodiment, in the copolymer of the 2nd sheath resin which forms a 2nd sheath layer, the mass ratio (B) of (A) ethylene unit and (B) tetrafluoroethylene unit in this copolymer ) / (A) is 1.4 to 1.7, and the mass ratio (C) / (A) of (A) ethylene units to (C) hexafluoropropylene units is 0.75 to 0.95. . The mass ratio (B) / (A) is more preferably 1.5 to 1.6. When the mass ratio (B) / (A) is within the above range, the obtained multi-core plastic optical fiber can be easily separated into individual single-core plastic optical fibers at the interface between the first sheath layer and the second sheath layer. It can be solved one by one, and the optical transmission of each single-core plastic optical fiber is improved. The mass ratio (C) / (A) is more preferably 0.80 to 0.90. When the mass ratio (C) / (A) is within the above range, the obtained multi-core plastic optical fiber can be easily broken into individual single-core plastic optical fibers one by one. The optical transmission of each single-core plastic optical fiber is improved.

  The copolymer of the second sheath resin contains at least one of a carbonate group and a haloformyl group, and the mass ratio of (A) to (C) in the copolymer of the second sheath resin is in the above range. When the copolymer is used as the second sheath layer, it becomes possible to easily unravel each individual single-core plastic optical fiber at the interface between the first sheath resin and the second sheath resin.

  Furthermore, the adhesion between the first sheath resin and the second sheath resin described above has sufficient adhesion to allow the light incident on and penetrating the first sheath resin to be totally reflected at the boundary surface of the second sheath resin. The light loss when the optical fiber is bent can be greatly suppressed. In particular, when a carbonate group is contained in the copolymer of the second sheath resin, the obtained multi-core plastic optical fiber is excellent in workability for individual single-core plastic optical fiber, and also has bending properties. Excellent and preferred. Further, when at least one of a carbonate group and a haloformyl group is present at the terminal of the copolymer of the second sheath resin, the resulting multi-core plastic optical fiber is unwound into individual single-core plastic optical fibers. Excellent in bending properties and bending properties are preferable.

  Introduction of a carbonate group or a haloformyl group into the copolymer of the second sheath resin or at the end of the copolymer can be carried out by a known method. For example, a method using a polymerization initiator capable of introducing a carbonate group or a haloformyl group can be used as a polymerization initiator for obtaining a copolymer of the second sheath resin. It is preferable that the usage-amount of such a polymerization initiator is 0.05-20 mass parts of this polymerization initiator with respect to 100 mass parts of copolymers of 2nd sheath resin. For example, a carbonate group can be easily introduced by using peroxycarbonate as a polymerization initiator during polymerization. The haloformyl group can be obtained by heating and thermally decomposing a copolymer having a carbonate group obtained by the above-described method.

  The carbonate group or haloformyl group may be introduced into the main chain of the second sheath resin copolymer, or may be introduced into the side chain of the second sheath resin copolymer. The carbonate group or haloformyl group may be introduced at the terminal of the main chain of the copolymer of the second sheath resin, or may be introduced at the terminal of the side chain of the copolymer of the second sheath resin. . In particular, the second sheath layer in which a carbonate group or a haloformyl group is introduced at one end of the copolymer of the second sheath resin is excellent in adhesion and peelability with the first sheath layer, and has a multi-core described later. A plastic optical fiber cable is preferred because of its excellent adhesion to the coating layer when the coating layer is formed. From the same viewpoint, it is particularly preferable that the carbonate group and the haloformyl group are introduced at both ends of the main chain of the copolymer of the second sheath resin. The copolymer of the second sheath resin may introduce both groups of carbonate groups and haloformyl groups.

There are no particular restrictions on the number of carbonate groups and haloformyl groups contained in the copolymer of the second sheath resin, but the copolymer of the second sheath resin has a carbonate group and haloformyl per 1 × 10 ⁶ carbon atoms. It is preferable to contain 3 to 1000 of at least one of the groups.

When carbonate groups are used, when the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the second sheath resin copolymer is 3 to 1000, the resulting multi-core plastic optical fiber strand Is preferable because it is excellent in workability for individual single-core plastic optical fibers. The copolymer of the second sheath resin contains 20 to 800, more preferably 50 to 700, and particularly preferably 100 to 600 carbonate groups per 1 × 10 ⁶ carbon atoms. .

When haloformyl groups are used, when the number of haloformyl groups contained per 1 × 10 ⁶ carbon atoms of the second sheath resin copolymer is 3 to 1000, the resulting multi-core plastic optical fiber Is preferable because it is excellent in workability for each individual single-core plastic optical fiber, and further, a decrease in transmission loss due to heat treatment is reduced. The copolymer of the second sheath resin contains 20 to 800, more preferably 50 to 700, particularly preferably 100 to 600 haloformyl groups per 1 × 10 ⁶ carbon atoms. .

In particular, when both carbonate groups and haloformyl groups are used, it is obtained when the total number of carbonate groups and haloformyl groups contained per 1 × 10 ⁶ carbon atoms of the copolymer is 3 to 1000. A multi-core plastic optical fiber is preferable because it is excellent in workability for each single-core plastic optical fiber and further reduces transmission loss due to heat treatment. The copolymer of the second sheath resin has more preferably 20 to 800, more preferably 50 to 700, and particularly preferably 100 to 600 carbonate groups and haloformyl groups per 1 × 10 ⁶ carbon atoms. Contains.

The number of carbonate groups and haloformyl groups contained per 1 × 10 ⁶ carbon atoms of the copolymer of the second sheath resin is determined by the polymerization initiator used when introducing the carbonate groups or haloformyl groups into the copolymer. It can be adjusted by adjusting the amount.

In the present embodiment, the number of carbonate groups and haloformyl groups contained per 1 × 10 ⁶ carbon atoms of the copolymer of the second sheath resin can be measured by the method described in the examples below. it can.

  The melting point of the second sheath resin copolymer is preferably in the range of 150 ° C. to 200 ° C., more preferably in the range of 155 to 200 ° C., and still more preferably in the range of 155 to 195 ° C. . When the melting point of the copolymer of the second sheath resin is in the above temperature range, the thermal decomposition of the resin constituting the core, for example, polymethyl methacrylate resin, is suppressed when the multi-core plastic optical fiber is formed. It is preferable because molding is possible at a molding temperature of 300 ° C. or less.

  In the present embodiment, the melting point of the copolymer of the second sheath resin can be measured by differential scanning calorimetry (DSC).

  The second sheath resin copolymer has a melting point in the range of 150 ° C. to 200 ° C. and a melt flow rate of 5 to 100 g / 10 min. It is preferable because it can be molded at a molding temperature of 300 ° C. or lower that can suppress thermal decomposition of a resin constituting the core, for example, polymethyl methacrylate resin.

  The melt flow rate of the copolymer of the second sheath resin is more preferably 6 to 80 g / 10 minutes, and further preferably 7 to 50 g / 10 minutes.

  In the present embodiment, the melt flow rate is a value measured under conditions of 230 ° C., a load of 3.8 kg, an orifice diameter of 2 mm, and a length of 8 mm in accordance with ASTM D1238.

  The refractive index of the copolymer of the second sheath resin is more preferably 1.37 to 1.41, and further preferably 1.375 to 1.405.

  In the present embodiment, the refractive index is a value measured at 20 ° C. using a sodium D line.

  The copolymer of the second sheath resin preferably has a melting point in the range of 150 to 200 ° C., a refractive index of 1.37 to 1.41, and a melt flow rate of 5 to 100 g / 10 minutes. .

  The copolymer of the second sheath resin preferably has a Shore D hardness value at 23 ° C. in the range of 50 to 90, more preferably in the range of 55 to 85, and in the range of 60 to 80. Is more preferable.

  In the present embodiment, the value of Shore D hardness at 23 ° C. is a value measured according to ASTM D2240.

  The number average molecular weight of the copolymer of the second sheath resin is preferably 1000 to 1000000, and more preferably 1500 to 500000.

  In the present embodiment, the number average molecular weight is a value measured by gel permeation chromatography GPC. Specifically, by gel permeation chromatography GPC, Tosoh Corporation GPCHLC-8020 was used, Shodex column (one GPC KF-801, one GPC KF-802, one GPC KF- 806M is used in series, and tetrahydrofuran is used as a solvent, and tetrahydrofuran is used as a solvent, and the flow rate is 1 ml / min.

  The weight average molecular weight of the copolymer of the second sheath resin is preferably 1400 to 1400000, and more preferably 2100 to 700000.

  In the present embodiment, the weight average molecular weight is a value measured by the gel permeation chromatography GPC.

<Additive component>
The core resin, the first sheath resin, and the second sheath resin described above may contain an additive component other than the copolymer as long as the effects of the present invention are not impaired. Depending on the purpose of use, additives such as antioxidants, ultraviolet absorbers, light stabilizers, metal deactivators, lubricants, flame retardant (auxiliary) agents, fillers and the like can be used.

<Structure of multi-core plastic optical fiber>
In the multi-core plastic optical fiber of the present embodiment, preferable application ranges such as the number of cores, the diameter of the core, and the diameter of the multi-core plastic optical fiber are described below.

  If the number of the cores is at least 7, it is possible to arrange them in a circular shape, and the maximum number is not particularly limited, but is preferably about 30000 because of the ease of manufacturing the multi-core plastic optical fiber. More preferably, it is 19 to 10000, and particularly preferably 19 to 3000.

  The diameter of the core is preferably 5 μm to 500 μm. More preferably, they are 20 micrometers-250 micrometers, More preferably, they are 50 micrometers-200 micrometers. The smaller the diameter of the core, the smaller the light loss due to bending, but the greater the transmission loss as an optical fiber. Since the multi-core plastic optical fiber of the present embodiment has a two-layer sheath structure as described above, even if the core diameter is increased, the light quantity loss due to bending can be relatively suppressed. Therefore, the multi-core plastic optical fiber strand of this Embodiment can suppress the loss of light quantity and can also reduce the transmission loss value as an optical fiber.

  The diameter of the multi-core plastic optical fiber wire of the present embodiment is preferably 0.1 mm to 3 mm. If it is less than 0.1 mm, it is too thin and difficult to handle, and if it exceeds 3 mm, it becomes rigid and difficult to handle. More preferably, it is 0.5 to 1.5 mm.

  Next, the ratio of the total cross-sectional area of the core, the total cross-sectional area of the first sheath layer, and the total cross-sectional area of the second sheath layer to the multi-core plastic optical fiber strand cross-sectional area will be described.

  The ratio of the total cross-sectional area of the core is preferably 60% to 90%, more preferably 70% to 85%. If it is less than 60%, the amount of light tends to decrease. If it exceeds 90%, the core is deformed from a circular shape, so that transmission loss tends to increase.

  The total cross-sectional area of the first sheath layer is preferably 3% to 30%, more preferably 5% to 15%. The first sheath layer has a role as a light transmission layer in addition to the role as a reflection layer. If the total cross-sectional area of the first sheath layer is too large, the light absorption loss tends to increase. From such a viewpoint, when the first sheath layer is formed in a substantially ring shape around the core, it is preferable to cover the first sheath layer with a thin thickness of about 0.8 μm to 3 μm.

  The ratio of the total cross-sectional area of the second sheath layer is preferably 3% to 30%, more preferably 7% to 20%. The thickness is preferably about 1 μm to 20 μm.

≪Multi-core plastic optical fiber cable≫
The multi-core plastic optical fiber cable of the present embodiment includes the above-described multi-core plastic optical fiber, and a coating layer containing a thermoplastic resin formed outside the multi-core plastic optical fiber. Have.

  The above-described multi-core plastic optical fiber can be used as it is. However, by using a multi-core plastic optical fiber cable in which a coating layer is formed on the outer periphery of the multi-core plastic optical fiber, the machine The chemical and chemical durability can be improved. As the resin to be contained in the coating layer, thermoplastic resins such as polyethylene resin, polyvinyl chloride resin, polypropylene resin, polyester resin, polyurethane resin, polyamide resin, and polyolefin elastomer resin can be used. When a multi-core plastic optical fiber cable is used as a light emitting decoration, the covering portion may be peeled off and the multi-core plastic optical fiber may be unwound. Of course, the multi-core plastic optical fiber cable can also be used for applications other than light-emitting decoration, communication, and the like.

  When the coating layer is formed, the copolymer of the second sheath resin that constitutes the multicore plastic optical fiber is particularly preferably a copolymer containing a carbonate group. The carbonate group can be easily introduced by using peroxycarbonate as a polymerization initiator at the time of polymerization, has excellent adhesiveness with a wide range of resins, especially excellent adhesiveness with polyamide resins such as nylon 12 etc. Have advantages. As a result, excellent chemical resistance, heat resistance, etc. can be imparted to the multicore plastic optical fiber. In coating the coating layer, a method of forming the coating layer on the multi-core plastic optical fiber using a crosshead die can be preferably used.

[Evaluation method]
(1) Refractive index measurement The value measured at 20 ° C. using sodium D line was adopted.

(2) Melt flow rate measurement In accordance with ASTM D1238, measurement was performed under the conditions of 230 ° C., load 3.8 kg, orifice diameter 2 mm, and length 8 mm.

(3) Measurement of the number of carbonate groups A piece of melt-extruded pellets of the obtained sheath resin was compression-molded at room temperature to prepare a film having a thickness of 0.1 mm. From the infrared absorption spectrum analysis of this film, a peak to which the carbonyl group of the carbonate group [—OC (═O) O—] belongs appears at an absorption wavelength of 1809 cm ⁻¹ (νC═O), and the absorbance of the νC═O peak. Was measured. The measured absorption spectrum was compared with the infrared absorption spectrum of a known film, and the number (N) of carbonate groups per 1 × 10 ⁶ carbon atoms was calculated from the difference spectrum by the following formula.

N = (L × K) / t
N: Number of carbonate groups per 1 × 10 ⁶ carbon atoms
L: Absorbance of ν (C═O) peak derived from carbonate group [—OC (═O) O—] K: Correction coefficient t: Film thickness (mm)
The correction coefficient K was calculated by the following calculation formula.

K = 500W / εd
W: Average molecular weight of monomer calculated from copolymer composition ε: Molar absorbance coefficient of ν (C═O) peak derived from carbonate group [—OC (═O) O—]. From the model compound, ε = 170 (l · cm ⁻¹ · mol ⁻¹ ) was set.

d: film density (g / cm ³ )
The infrared absorption spectrum analysis was performed by scanning 40 times using a Perkin-Elmer FTIR spectrometer 1760X (manufactured by Perkin Elmer). The obtained IR spectrum was analyzed using Perkin-Elmer Spectrum for Windows (registered trademark) Ver. The baseline was automatically determined at 1.44 C, and the absorbance at the peak at 1809 cm ⁻¹ was measured. The film thickness was measured with a micrometer.

[Solving test]
A multi-core plastic optical fiber is cut to a length of 1 m and bent 10 reciprocally about 10 mm from one end with a finger at +90 degrees to 90 degrees, and multi-core at the interface between the first sheath layer and the second sheath layer. It was tested whether the plastic optical fiber could be unwound one by one.

  In the case of a multi-core plastic optical fiber, a case where all the single-core plastic optical fibers are unwound one by one at the interface between the first sheath layer and the second sheath layer, and the first sheath layer and the second sheath The case where there was a single-core plastic optical fiber that could not be unwound at the interface with the layer was taken as x.

[Optical transmission test]
With respect to the multi-core plastic optical fiber after the unraveling test, LED light having a wavelength of 650 nm and an incident NA of 0.6 was incident from the end surface on the opposite side to the unraveled side, and the end surface on the unraveled side was visually observed. In the case where light was transmitted through all the cores, it was marked as ◯, and in the case where light was not transmitted through some cores, it was marked as x.

<Example 1>
Polymethylmethacrylate having a refractive index of 1.492, a weight average molecular weight of 110,000, and a melt flow rate of 1.5 g / 10 min as a resin constituting the core (hereinafter also referred to as “core resin”) Resin was used.

  As the first sheath resin, a copolymer obtained by cast polymerization of 20% by mass of tetrafluoropropyl methacrylate (4FM), 60% by mass of pentafluoropropyl methacrylate (5FM), and 20% by mass of methyl methacrylate (MMA) is used. It was.

  As the second sheath resin, a copolymer obtained by polymerizing each monomer component of (A) ethylene, (B) tetrafluoroethylene, and (C) hexafluoropropylene with di-n-propyl peroxydicarbonate. used. The copolymer had a carbonate group introduced at the terminal (hereinafter referred to as a carbonate group-containing copolymer). The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer is 1.56, and the mass ratio of (A) and (C) (C) / ( A) was 0.86.

The total content of (A) to (C) in the carbonate group-containing copolymer is 97% by mass, and the content of the carbonate group-containing copolymer in the second sheath resin is 100% by mass. Met. The number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer was 253.

  As the composite spinning die, there was used a die having 19 cores, each of which has a structure in which the first sheath and the second sheath cover the core in two layers. The composite spinning die is fed so that the volume ratio of the core resin, the first sheath resin, and the second sheath resin is 80:10:10 in order, and the strands discharged from the die are converged to double To produce a two-sheath multi-core plastic optical fiber having a diameter of 1.00 mm.

  When a transmission loss test was performed with this multi-core plastic optical fiber, it was 128 dB / km. Next, when the obtained multi-core plastic optical fiber was unwound as described above, all the single-core plastic optical fibers were easily unwound one by one. Next, when an optical transmission test was performed, all the 19 cores passed light, and each core functioned as an optical fiber.

<Examples 2 to 9>
The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer and the mass ratio (C) / (A) of (A) and (C) are shown. A multi-core plastic optical fiber was prepared in the same manner as in Example 1 except that the number was changed to 1. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 1. The “number of carbonate groups” in Table 1 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Comparative Examples 1-8>
The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer and the mass ratio (C) / (A) of (A) and (C) are shown. A multi-core plastic optical fiber was prepared in the same manner as in Example 1 except that the number was changed to 1. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 1. The “number of carbonate groups” in Table 1 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Example 10>
The multicore plastic optical fiber element is the same as in Example 1 except that the blending amounts (mass%) of 4FM, 5FM, and MMA in the first sheath resin are changed to 17 mass%, 50 mass%, and 33 mass% in this order. Created a line. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 2. The “number of carbonate groups” in Table 2 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Examples 11 to 18>
The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer and the mass ratio (C) / (A) of (A) and (C) are shown. A multi-core plastic optical fiber was prepared in the same manner as in Example 10 except that the change was made as in 2. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 2. The “number of carbonate groups” in Table 2 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Comparative Examples 9-16>
The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer and the mass ratio (C) / (A) of (A) and (C) are shown. A multi-core plastic optical fiber was prepared in the same manner as in Example 10 except that the change was made as in 2. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 2. The “number of carbonate groups” in Table 2 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Example 19>
A multi-core plastic optical fiber element in the same manner as in Example 1 except that the blending amounts (mass%) of 4FM, 5FM, and MMA in the first sheath resin were changed to 30 mass%, 60 mass%, and 10 mass% in this order. Created a line. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 3. The “number of carbonate groups” in Table 3 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Examples 20 to 27>
The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer and the mass ratio (C) / (A) of (A) and (C) are shown. A multi-core plastic optical fiber was prepared in the same manner as in Example 19 except that the change was made as in 3. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 3. The “number of carbonate groups” in Table 3 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Comparative Examples 17-24>
The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer and the mass ratio (C) / (A) of (A) and (C) are shown. A multi-core plastic optical fiber was prepared in the same manner as in Example 19 except that the change was made as in 3. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 3. The “number of carbonate groups” in Table 3 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Comparative Example 25>
The multicore plastic optical fiber element is the same as in Example 1 except that the blending amounts (mass%) of 4FM, 5FM, and MMA in the first sheath resin are changed to 20 mass%, 40 mass%, and 40 mass% in this order. Created a line. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 4. The “number of carbonate groups” in Table 4 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Comparative Examples 26-27>
The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer and the mass ratio (C) / (A) of (A) and (C) are shown. A multi-core plastic optical fiber was prepared in the same manner as in Comparative Example 25 except that the change was made as in 4. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 4. The “number of carbonate groups” in Table 4 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Comparative Example 28>
A multi-core plastic optical fiber element in the same manner as in Example 1 except that the blending amounts (mass%) of 4FM, 5FM, and MMA in the first sheath resin were changed to 35 mass%, 60 mass%, and 5 mass% in this order. Created a line. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 4. The “number of carbonate groups” in Table 4 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Comparative Examples 29-30>
The mass ratio (B) / (A) of (A) and (B) in the carbonate group-containing copolymer and the mass ratio (C) / (A) of (A) and (C) are shown. A multi-core plastic optical fiber was prepared in the same manner as in Comparative Example 25 except that the change was made as in 4. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 4. The “number of carbonate groups” in Table 4 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

<Comparative Examples 31-57>
A multicore plastic optical fiber as in Examples 1 to 27 except that ammonium persulfate was used in place of di-n-propyl peroxydicarbonate as a polymerization initiator in the production of the second sheath resin copolymer. A strand was created. The produced multi-core plastic optical fiber had no carbonate group introduced therein. When the unwinding test and the optical transmission test were performed in the same manner as in Example 1 using the prepared multicore plastic optical fiber, the unwinding test was performed with all the multicore plastic optical fibers of Comparative Examples 31 to 57. As a result, an optical transmission test x was obtained.

<Examples 28 to 34>
When producing the copolymer of the second sheath resin, the blending amount of di-n-propyl peroxydicarbonate is adjusted, and the carbonate group contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer. A multi-core plastic optical fiber was produced in the same manner as in Example 1 except that the number was changed as shown in Table 5. Using the prepared multi-core plastic optical fiber, the unwinding test and the optical transmission test were performed in the same manner as in Example 1. The results are shown in Table 5. The “number of carbonate groups” in Table 5 refers to the number of carbonate groups contained per 1 × 10 ⁶ carbon atoms of the carbonate group-containing copolymer.

  The multi-core plastic optical fiber and cable according to the present invention can be used by easily detaching each single-core plastic optical fiber, and the optical transmission of each single-core plastic optical fiber is good. Therefore, it is optimal for use as an electrical decoration and has industrial applicability.

10 Multi-core plastic optical fiber 1 Core fiber 2 Sheath layer 3 Sea part

Claims (7)

A multi-core including a plurality of cores made of resin, a first sheath layer made of a first sheath resin surrounding the core, and a second sheath layer made of a second sheath resin in contact with the outer periphery of the first sheath layer A plastic optical fiber,
The first sheath resin is composed of a copolymer mainly composed of the following components (a) and (b):
The mass ratio ((b) / (b)) between the component (b) and the component (b) in the first sheath resin is 2 to 10,
The second sheath resin is made of a copolymer having the following units (A), (B) and (C) as the main component of the polymerization unit,
The mass ratio ((B) / (A)) of the unit (A) and the unit (B) in the copolymer of the second sheath resin is 1.4 to 1.7,
The mass ratio ((C) / (A)) of the unit (A) to the unit (C) in the copolymer of the second sheath resin is 0.75 to 0.95, and
A multicore plastic optical fiber in which the copolymer of the second sheath resin contains at least one of a carbonate group and a haloformyl group;
(A) a fluoroalkyl methacrylate represented by the following formula (i):
(In the formula (i), n is 1 or 2, m ₁ is 0 or an integer of 1 to 4, and X is a hydrogen atom or a fluorine atom)
(B) methyl methacrylate,
(A) ethylene units,
(B) tetrafluoroethylene unit,
(C) Hexafluoropropylene unit.   2. The multi-core plastic optical fiber according to claim 1, wherein the copolymer of the second sheath resin contains at least one of a carbonate group and a haloformyl group at a terminal thereof. 3. The multi-core plastic optical fiber according to claim 1, wherein the copolymer of the second sheath resin contains 3 to 1000 at least one of a carbonate group and a haloformyl group per 1 × 10 ⁶ carbon atoms. Strands.   The copolymer of the second sheath resin has a melting point in the range of 150 to 200 ° C., the refractive index measured at 20 ° C. with sodium D line is 1.37 to 1.41, and the melt flow rate (230 The multi-core plastic optical fiber according to any one of claims 1 to 3, wherein a temperature (° C, a load of 3.8 kg, an orifice diameter of 2 mm, a length of 8 mm) is 5 to 100 g / 10 minutes.   The multi-core plastic according to any one of claims 1 to 4, wherein the copolymer of the second sheath resin has a Shore D hardness value (measured in accordance with ASTM D2240) at 23 ° C of 50 to 90. Optical fiber strand.   The multi-core plastic optical fiber according to any one of claims 1 to 5, wherein the resin constituting the core is a polymethyl methacrylate resin. The multi-core plastic optical fiber according to any one of claims 1 to 6,
A multi-core plastic optical fiber cable having a coating layer containing a thermoplastic resin formed on the outside of the multi-core plastic optical fiber.