JP2009237571A - Plastic optical fiber cable and signal transmitting method - Google Patents

Abstract

A plastic optical fiber cable excellent in heat resistance is provided.
In a plastic optical fiber cable having a core made of polymethyl methacrylate or a copolymer mainly composed of methyl methacrylate, a clad and a coating layer, the clad is a layer made of a specific fluorine-containing olefin resin. At least on the outermost layer, and the coating layer is composed of a light shielding coating layer and a functional coating layer in order from the inside. The functional coating layer contains a brominated polymer flame retardant, has a specific crystal melting point, and transmits oxygen. The light blocking coating layer is made of a nylon resin composition that is uncolored or colored with an inorganic pigment, with a rate P (cm ³ · cm / (cm ² · sec · Pa)) satisfying a specific relationship. And nylon 12 as a main component, and the total content of the monomer compound and oligomer compound derived from the nylon resin is special. It is formed from a resin composition in a certain range.
[Selection] Figure 1

Description

  The present invention relates to a plastic optical fiber cable capable of stably transmitting signals over a long period of time in a high temperature environment of about 100 to 110 ° C., and visible light emission having a light emission center in the range of 500 nm to 600 nm. The present invention relates to a signal transmission method using a combination of diodes.

  Conventionally, as an optical fiber, a silica-based optical fiber capable of performing excellent optical transmission over a wide wavelength region has been put into practical use mainly in a trunk line system, but this silica-based optical fiber is expensive and has low workability. Therefore, a plastic optical fiber (hereinafter abbreviated as POF) having advantages such as lower cost, lighter weight, large diameter, and easy end face processing and handling can be used for lighting applications, sensor applications, FA, OA. It has been put to practical use in the field of indoor wiring applications such as LAN.

  In particular, a POF cable having a coating layer formed on the outer periphery of a step index type (SI type) POF having a core-clad structure with polymethyl methacrylate (PMMA) as a core material enables high-speed data communication. From the standpoint of weight reduction, cost reduction of the communication system, countermeasures against electromagnetic noise, etc., it is being put into practical use as a wiring for LAN communication in an automobile.

  When a POF cable is used in an engine room or a ceiling part of an automobile, it is desired that a signal can be stably transmitted over a long period of time in a high temperature environment of about 100 to 110 ° C.

  On the other hand, a light emitting diode (LED) having an emission center wavelength near 650 nm, which has been used as a POF light source, has a problem that heat resistance at 100 ° C. or higher is insufficient. The reason is that such an LED is formed from a GaAlAs-based material, and if the content of the Al component is large, the heat resistance of the LED itself tends to be reduced.

  As a signal transmission system excellent in heat resistance at 100 ° C. or higher, Patent Document 1 (Japanese Patent Laid-Open No. 2001-74945) discloses an LED having a light emission center at 930 to 990 nm and a POF having a norbornene resin as a core material. A signal transmission system consisting of an LED having an emission center of 750 to 850 nm and a POF having a polycarbonate resin as a core material is disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2001-21737). It is disclosed. Such an LED having an emission center in the near-infrared wavelength region has a low Al component composition ratio, and therefore the heat resistance of the LED itself at 100 ° C. or higher is excellent. Furthermore, when the POF is placed in such a high temperature environment, as a general phenomenon, the electron transition absorption increases due to the thermal oxidation deterioration of the POF strand portion, or the low molecular weight compound contained in the coating material is POF. Rayleigh scattering increases by moving into the strand, but the transmission loss value in the near infrared wavelength region is hardly affected. Therefore, in the signal transmission quality system described in the above-mentioned patent document, the change over time of the transmission loss is small even under a high temperature environment of 100 ° C. or higher, and it was possible to stabilize the transmission loss for a sufficiently long period. .

  However, the transmission loss at 930 to 990 nm of the POF having the norbornene resin described in Patent Document 1 as a core material is on the order of 6000 dB / km, and the polycarbonate resin described in Patent Document 2 is used as a core material. The transmission loss of POF at 750 to 850 nm is in the 1000 dB / km range, and the POF transmission loss described in both patent documents is extremely high, which is insufficient for practical use as a wiring for LAN communication in an automobile. .

  On the other hand, as a visible light LED having an emission center wavelength of 600 nm or less, an InGaN system (emission center wavelength 505 nm, 520 nm), a PGaN system (emission center wavelength 565 nm), an InGaAlP system (emission center wavelength 590 nm), and the like are known. Since the composition ratio is small even if it does not contain an Al component that causes a decrease in the heat resistance of the LED, or has been included, the heat resistance of the LED itself at 100 ° C. or higher has reached a level at which it can be practically used. Furthermore, POF whose core material is PMMA resin has a transmission loss window (80 to 90 dB / km) in the vicinity of a wavelength of 570 nm, and a transmission loss value compared with a window in the vicinity of a wavelength of 650 nm (about 130 to 140 dB / km). There is also a feature that is extremely low.

  However, in such a short wavelength region, when the POF is placed in a high temperature environment of 100 ° C. or higher, it is easily affected by the above-described increase in electronic transition absorption and Rayleigh scattering, so that POF transmission loss increases. There is a problem that it is easy. Therefore, it has been considered difficult to put into practical use a signal transmission system using POF and an LED having a light emission center in the wavelength range of 500 to 600 nm in a high temperature environment such as in an automobile.

JP 2001-74945 A Japanese Patent Laid-Open No. 2001-21737

  An object of the present invention is to provide a plastic optical fiber cable excellent in heat resistance and a signal transmission method using the same.

According to the present invention, there is provided a plastic optical fiber cable having a core and a clad layer composed of one or more layers formed on the outer periphery of the core, and a plastic optical fiber cable having a coating layer on the outer periphery thereof.
The core is made of polymethyl methacrylate or a copolymer mainly composed of methyl methacrylate,
The clad layer has at least an outermost layer comprising a fluoroolefin-based resin containing a tetrafluoroethylene unit and having a heat of crystal melting in differential scanning calorimetry (DSC) of 40 mJ / mg or less,
The coating layer is composed of a light shielding coating layer and a functional coating layer in order from the inside,
The functional coating layer contains a bromine-based polymer flame retardant, has a crystal melting point by differential scanning calorimetry (DSC) in the range of 240 ° C. or higher and 280 ° C. or lower, and is defined in ISO 14663-2: 1999 (Annex C). The oxygen permeability P (cm ³ · cm / (cm ² · sec · Pa)) at the temperature T (K) measured by the above method is expressed by the following general formula (1)
P <8 × 10 ⁻² × exp (−5600 / T) (1)
Satisfying, formed from a non-colored or pigmented nylon resin composition with an inorganic pigment,
The light shielding coating layer contains at least one nylon resin of nylon 11 and nylon 12 as a main component, and the total content of monomer compounds and oligomer compounds derived from the nylon resin contained is 1.5% by mass or less. There is provided a plastic optical fiber cable formed from a resin composition in the range of

  According to the present invention, there is provided the plastic optical fiber cable, wherein the functional coating layer is formed from a nylon resin composition having a crystallinity in the range of 30% to 55%.

  According to the invention, any one of the above plastics, wherein the functional coating layer is formed from a nylon resin composition having an average diameter of spherulite size by microscopic observation in the range of 0.01 μm to 40 μm. A fiber optic cable is provided.

  In addition, according to the present invention, there is provided any one of the above plastic optical fiber cables, wherein the functional coating layer is formed from a nylon resin composition mainly composed of nylon 66.

  Further, according to the present invention, the functional coating layer contains bromine-substituted polystyrene or poly (brominated benzyl acrylate) as the brominated polymer flame retardant, and the bromine atom content is 1.5% by mass or more and 30% by mass or less. The plastic optical fiber cable according to any one of the above is provided, which is formed from a nylon-based resin composition containing the antimony oxide in the range of 0 to 20% by mass.

  According to the invention, the plastic according to any one of the above, wherein the functional coating layer is formed from a nylon resin composition containing an inorganic pigment in a range of 0.1% by mass to 10% by mass. A fiber optic cable is provided.

  According to the present invention, a polybutylene terephthalate resin, a (meth) methyl acrylate resin, a styrene resin, a vinylidene fluoride homopolymer, between the plastic optical fiber and the light shielding coating layer, Any one of the above plastic optical fiber cables having a protective coating layer made of a resin selected from a copolymer containing ethylene units and vinyl alcohol units is provided.

  According to the invention, a signal transmission is characterized in that the plastic optical fiber cable according to any one of the above is combined with a visible light emitting diode having an emission center in a wavelength range of 500 nm to 600 nm. A method is provided.

  According to the present invention, it is possible to provide a plastic optical fiber cable excellent in heat resistance and a signal transmission system using the same.

It is sectional drawing of an example of the plastic optical fiber cable by this invention. It is sectional drawing of the other example (when it has a protective coating layer) of the plastic optical fiber cable by this invention. It is sectional drawing of an example of the coating | coated apparatus used for this invention. The total wavelength transmission loss of the POF cable at the initial stage of Reference Example 1 and after 105 hours at 105 ° C. is shown. The total wavelength transmission loss of the POF cable at the initial stage of Reference Example 3 and after 105 hours at 105 ° C. is shown. The total wavelength transmission loss of the POF cable of Example 2 after the initial stage and 105 degreeC and 5000 hours is shown.

  The present inventors have found that the reason why the transmission loss of a plastic optical fiber cable (POF cable) increases in a high-temperature (or high-temperature and high-humidity) environment is that the low-molecular compound contained in the coating material is a plastic optical fiber element. Rayleigh scattering increases by moving into the wire (POF strand), and oxygen in the environment where the POF cable is left passes through the coating material and penetrates and diffuses into the POF strand to cause oxidative degradation. It has been found that this is due to the increase in electronic transition absorption. Further, in the structure of the coating layer of the POF cable, the amount of low-molecular compounds (monomers and oligomers) transferred to the POF strand is suppressed, and the oxygen transmission rate is reduced by the coating layer made of a nylon resin composition having low oxygen permeability. It was found that by suppressing the increase in Rayleigh scattering and electronic transition absorption, it is possible to suppress not only the transmission loss of POF wavelength 650 nm but also the increase of transmission loss of wavelength 600 nm or less.

  The preferred embodiments of the POF cable of the present invention will be described below.

[Basic structure of POF cable]
As shown in FIG. 1, the POF cable of the present invention includes a core, a POF strand 101 having a core / cladding structure formed of at least one clad formed on the outer periphery thereof, and an inner layer side provided on the outer periphery thereof. In order, the light-blocking coating layer 102 and the functional coating layer 103 are provided.

[POF strand]
In the POF cable of the present invention, the material (core material) constituting the core of the POF strand is not particularly limited, but from the viewpoint of satisfying long-term heat resistance at around 105 ° C., polymethyl methacrylate (PMMA) and copolymers having methyl methacrylate (MMA) units as main components are preferred (hereinafter referred to as PMMA resins). The copolymer is preferably a copolymer comprising methyl methacrylate (MMA) units and one or more types of vinyl monomer units. Among PMMA-based resins, PMMA excellent in balance between transparency and mechanical strength is particularly preferable. When the core material is a copolymer having MMA as a main component, the content of the MMA unit is preferably 50% by mass or more, more preferably 60% by mass or more, from the viewpoint of sufficiently ensuring transparency. The mass% or more is more preferable. As a copolymerization component for MMA, a component used in a material proposed so far as a raw material for a core material for POF, such as methacrylic acid ester and acrylic acid ester, can be appropriately selected.

  The clad formed on the outer periphery of the core may be formed from one layer or may be formed from a plurality of layers of two or more layers. This clad has optical properties such as mechanical properties, heat resistance, chemical resistance, impact resistance, and low refractive index that can sufficiently reduce optical loss during bending to function as a protective material for the core or inner layer clad. From the viewpoint of characteristics, at least the outermost layer has a layer made of a fluorine-containing olefin resin. As this fluorine-containing olefin resin, a fluorine-containing olefin polymer having at least a tetrafluoroethylene (TFE) unit and a crystal melting heat of 40 mJ / mg or less is used.

  The fluorine-containing olefin polymer containing a TFE unit is at least one of a TFE unit, a vinylidene fluoride (VdF) unit, a hexafluoropropylene (HFP) unit, and a perfluoro (fluoro) alkyl vinyl ether (FVE) unit. A copolymer obtained by copolymerizing, a copolymer of VdF unit, TFE unit and hexafluoroacetone unit, a copolymer of TFE unit, HFP unit and ethylene unit, etc. Is not to be done. As a copolymerization component for TFE, a VdF unit, an HFP unit, or an FVE unit is particularly preferable from the viewpoint of cost, transparency, and heat resistance.

  In addition, a resin containing at least one of a VdF unit and an HFP unit in a fluorine-containing olefin polymer containing a TFE unit is preferable in terms of excellent stability during POF melt spinning.

  Specific examples of the fluorine-containing olefin polymer containing the TFE unit include a binary copolymer composed of 60 to 90% by mass of VdF units and 10 to 40% by mass of TFE units, 10 to 60% by mass of VdF units, A terpolymer comprising 20 to 70% by mass of TFE units and 5 to 35% by mass of HFP units, 5 to 25% by mass of VdF units, 50 to 80% by mass of TFE units, and 5 to 25% by mass of FVE units. A terpolymer comprising 5 to 60% by mass of ethylene units, 25 to 70% by mass of TFE units, and 5 to 45% by mass of HFP units, and 10 to 30% by mass of VdF units. A quaternary copolymer comprising 40 to 80% by mass of TFE units, 5 to 40% by mass of HFP units and 0.1 to 15% by mass of FVE units, 40 to 90% by mass of TFE units, and 10 to 10% of FVE units. 60% by mass 2 terpolymer, consisting of TFE units 30 to 75 wt%, HFP units 25 to 70 wt% bipolymer, and the like.

The FVE _{unit, CF 2 = CFOCF 3, CF} 2 = CFOCF 2 CF 3, CF 2 = CFOCF 2 CF 2 CF 3, CF 2 = CFOCH 2 CF 3, CF 2 = CFOCH 2 CF 2 CF 3, CF 2 = The unit of at least one compound selected from the group consisting of CFOCH ₂ CF ₂ CF ₂ CF ₃ , CF ₂ = CFOCH ₃ , CF ₂ = CFOCH ₂ CH ₃ and CF ₂ = CFOCH ₂ CH ₂ CH ₃ This is preferable because it can be obtained at low cost.

  Furthermore, in the present invention, it is necessary to use a resin having a crystal melting heat value of 40 mJ / mg or less by differential scanning calorimetry (DSC) as a fluorine-containing olefin polymer forming at least the outermost clad layer. A resin of mg or less is preferred, and a resin of 15 mJ / mg or less is more preferred. If the heat of crystal fusion is too high, especially if it exceeds 40 mJ / mg, the resin crystallinity will be high, and the transparency of the resin will be reduced in a high-temperature environment, and the POF cable will be transmitted in the initial and high-temperature environments. This causes an increase in loss. As the fluorine-containing olefin polymer constituting at least the outermost layer of the clad, a resin having a crystal melting heat within the above range, for example, 1 mJ / mg or more can be used.

  When the clad is formed of a plurality of layers, the resin that forms the inner clad on the inner layer side is a material proposed as a clad material for POF, such as a fluorinated methacrylate polymer or a vinylidene fluoride polymer. It can be selected appropriately. In particular, a fluorinated methacrylate polymer is preferable because it is easy to adjust the refractive index, has excellent transparency and heat resistance, and is excellent in flexibility and workability.

As the fluorinated methacrylate-based polymer, for example, as a polymer excellent in flexibility and workability while having good transparency and heat resistance,
The following general formula (6)
_{CH 2 = CX-COO (CH} 2) m -R 1f (6)
(Wherein, X represents a hydrogen atom, a fluorine atom, or a methyl group, R _1f represents a (fluoro) alkyl group having 1 to 12 carbon atoms, and m represents an integer of 1 or 2).
15 to 90% by mass of the (meth) acrylic acid fluorinated alkyl ester unit represented by the formula (B) and 10 to 85% by mass of the monomer unit (B) copolymerizable with the monomer of the unit (A). %, And a copolymer having a refractive index in the range of 1.39 to 1.475 can be used.

  As the unit (A) of the (meth) acrylic acid fluorinated alkyl ester, (meth) acrylic acid-2,2,2-trifluoroethyl (3FM), (meth) acrylic acid-2,2,3,3- Tetrafluoropropyl (4FM), (meth) acrylic acid-2,2,3,3,3-pentafluoropropyl (5FM), (meth) acrylic acid-2,2,3,4,4,4-hexafluoro Butyl (6FM), (meth) acrylic acid-1H, 1H, 5H-octafluoropentyl (8FM), (meth) acrylic acid-2- (perfluorobutyl) ethyl (9FM), (meth) acrylic acid-2- (Perfluorohexyl) ethyl (13FM), (meth) acrylic acid-1H, 1H, 9H-hexadecafluorononyl (16FM), (meth) acrylic acid-2- (perfluoroio Cyl) ethyl (17FM), (meth) acrylic acid-1H, 1H, 11H- (icosafluoroundecyl) (20FM), (meth) acrylic acid-2- (perfluorodecyl) ethyl (21FM), etc. However, it is not particularly limited.

  On the other hand, as a monomer unit (B) copolymerizable with the monomer of the unit (A), (meth) methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, etc. Examples of the unit include compounds such as alkyl acrylates and methacrylic acid, but are not particularly limited.

  From these, one or more kinds of compounds may be appropriately selected so as to satisfy the transparency and heat resistance of the clad material. Among them, methyl (meth) acrylate is preferable from the viewpoint that the transparency and heat resistance of the clad material and the mechanical strength can be improved in a well-balanced manner by copolymerizing with (meth) acrylic acid fluorinated alkyl ester. . Moreover, by including the methacrylic acid unit in the range of 0.5 to 5% by mass in the fluorinated methacrylate polymer, the adhesion to both the core material of the POF and the resin of the clad outermost layer can be improved. .

  When low bending loss is required for POF, the unit of 10 to 40% by mass of (meth) acrylic acid-2- (perfluorooctyl) ethyl (17FM) and (meth) acrylic acid-2,2,2 -Trifluoroethyl (3FM), (meth) acrylic acid-2,2,3,3-tetrafluoropropyl (4FM), (meth) acrylic acid-2,2,3,3,3-pentafluoropropyl (5FM) ) Is preferably a copolymer having 40 to 90% by mass of at least one unit and 0 to 20% by mass of methyl methacrylate and having a refractive index in the range of 1.39 to 1.43.

  When high transmission bandwidth is required for POF, (meth) acrylic acid-2,2,2-trifluoroethyl (3FM), (meth) acrylic acid-2,2,3,3-tetrafluoropropyl ( 4FM), (meth) acrylic acid-2,2,3,3,3-pentafluoropropyl (5FM), at least one unit of 15 to 30% by mass, and methyl methacrylate unit of 70 to 95% by mass. A copolymer having a refractive index in the range of 1.45 to 1.475 is preferred.

  As described above, the clad layer may be formed of a plurality of layers of two or more layers, but from the viewpoint of reducing the manufacturing cost, only the first clad is provided as the inner clad between the outermost clad and the core, It is preferable to have a two-layer structure including a first cladding and a second cladding layer as an outermost cladding around the first cladding.

[Light blocking coating layer]
Next, the light shielding coating layer constituting the POF cable of the present invention will be described.

  The POF cable of the present invention is made of a nylon resin (polyamide resin) containing a light shielding agent such as carbon black around the outer periphery of the POF strand having the core-clad structure described above to prevent the incidence of external light. A light blocking coating layer is provided.

  When the POF cable is laid in a high-temperature environment such as in the vicinity of the engine room of an automobile as wiring for LAN communication in an automobile, there is a flammable substance such as oil, electrolyte, gasoline, etc. At the same time, excellent chemical resistance is also required. Therefore, nylon 11 (homopolymer) or nylon 12 (homopolymer) excellent in heat resistance, flex resistance, chemical resistance, etc. is suitable as a nylon resin as a coating material for the POF cable. Nylon 11 and nylon 12 have good moldability in the coating process and have an appropriate melting point. Therefore, POF strands can be easily used without degrading the transmission performance of POF cables using PMMA resin as a core material. Can be coated.

  The light blocking coating layer may be formed from one nylon resin of nylon 11 and nylon 12, or a mixture of both may be used. Further, if necessary, other polymers and compounds can be added and used. Thus, when mix | blending other components, such as another polymer and a compound, it is preferable to add another component within the range of 50 mass% or less. When the amount of other components is more than 50% by mass, the characteristics of nylon 11 and nylon 12 become insufficient, so that the battery fluid resistance tends to decrease and the thermal dimensional stability of the POF cable tends to decrease. The material constituting the light shielding coating layer in the present invention is mainly composed of a nylon resin, and the content of the nylon resin component (the total content when both nylon 11 and nylon 12 are included) is 50% by mass or more. Is preferable, 70 mass% or more is more preferable, and 80 mass% or more is more preferable.

  In general, nylon resins such as nylon 12 are industrially obtained by a polycondensation reaction of an amine and a carboxylic acid. However, since polymerization of nylon resin is a chemical equilibrium reaction, it is inevitable that monomers and oligomers derived from the raw material of nylon resin remain in the produced polymer.

  According to the study by the present inventors, a POF cable provided with a primary coating layer made of nylon 11 or nylon 12 so as to be in contact with a POF strand is POF when left in a high temperature environment of 105 ° C. for a long time. There was a phenomenon that transmission loss increased significantly.

  The present inventors have conducted a detailed analysis of this cause, and as a result, the above-mentioned increase in transmission loss is caused by the residual monomers and oligomers derived from these raw materials from the primary coating layer and the secondary coating layer. It has been found that it has dissolved and diffused inside the wire, causing an increase in POF transmission loss.

  Furthermore, this phenomenon occurs when the outermost clad layer is a fluorine-containing olefin resin containing a tetrafluoroethylene (TFE) unit and the heat of crystal melting is a certain value or more. It was found that the increase in

  Examples of the monomer derived from the above-mentioned nylon resin raw material include an aliphatic diamino acid compound, an aliphatic dicarboxylic acid compound, an amino aliphatic carboxylic acid compound and the like constituting the nylon resin. -Aminoundecanoic acid, nylon 12 includes 12-aminododecanoic acid. Furthermore, by-products such as cyclic lactam compounds in which the molecular chain terminal of the aminocarboxylic acid compound is ester-cyclized in the molecule and an amide bond (—CONH—) is included in the ring, specifically, Nylon 12 includes lauryl lactam. Here, the monomer derived from the raw material includes a low molecular compound produced as a by-product during the raw material synthesis.

On the other hand, as the oligomer derived from the above-mentioned nylon resin raw material, the above-mentioned raw material monomers (the above-mentioned aliphatic diamino acid compound, aliphatic dicarboxylic acid compound, aminoaliphatic compound) in the process of condensation polymerization reaction at the time of nylon resin production Two or more molecular chain ends of the carboxylic acid compound, etc. are ester-bonded between the molecules, and both the amino group (—NH ₂ ) and the carboxyl group (—COOH) or one of the functional groups at the molecular chain terminal Or a cyclic lactam compound in which the end of the molecular chain of the compound has an ester cyclization bond in the molecule and an amide bond (-CONH-) in the ring, and an intermolecular ester bond of the above compound Furthermore, compounds generated by causing a side reaction (deamination reaction or decarboxylation reaction) between molecules / molecules are listed.

  When the monomer or oligomer is linear, the terminal amino group has a high affinity with the fluorinated olefin polymer and tends to stay inside the clad layer made of the fluorinated olefin polymer. For this reason, the transparency of the clad material is lowered, and the transmission characteristics of the POF cable tend to be remarkably lowered. On the other hand, when the monomer or oligomer is a cyclic lactam compound, it easily moves to the vicinity of the interface on the inner layer side (core or first cladding layer) of the cladding layer to form a particulate structure. Therefore, when the POF core-cladding interface or the clad is a multilayer, structural irregularities at the cladding-cladding interface increase, and the transmission characteristics of the POF cable tend to be remarkably deteriorated.

  The above-mentioned oligomer tends to be dissolved and diffused into the POF strand as the molecular weight is low, and the influence is particularly remarkable at a molecular weight of 2000 or less.

  As described above, the POF cable is required to have excellent heat resistance, and particularly when the POF cable is used in an automobile, the increase in transmission loss over a long period exceeding 5000 hours in a 105 ° C environment. Is required to be small.

  In the POF cable of the present invention, in order to make the long-term heat resistance of the POF cable higher, the light shielding coating layer is a resin material mainly composed of at least one nylon resin of nylon 11 and nylon 12. And the total content of the monomer compound derived from the nylon resin contained in this material and an oligomer compound needs to be formed with the resin material which exists in the range of 1.5 mass% or less. The total content of the monomer compound and the oligomer compound is preferably in the range of 1.3% by mass or less, more preferably in the range of 1.0% by mass or less, and in the range of 0.8% by mass or less. Is particularly preferred. If the content of the monomer compound and oligomer compound in the light shielding coating layer is too large, especially if it is more than 1.5% by mass, the amount of the monomer compound and oligomer compound in the light shielding coating layer transferred to the POF strand is large. As a result, the transmission loss is significantly reduced. As described above, when the total content of the monomer compound and the oligomer compound in the light blocking coating layer is within the above range, the migration amount of the monomer compound and the oligomer compound in the light blocking coating layer to the POF strand can be kept low. .

  The above-mentioned oligomer compound tends to be dissolved and diffused into the POF strand as the molecular weight is low. Since the influence is particularly noticeable at a molecular weight of 2000 or less, the oligomer compound and monomer having a molecular weight of 2000 or less. The total content of the compounds is preferably 1.5% by mass or less, more preferably in the range of 1.3% by mass or less, still more preferably in the range of 1.0% by mass or less. If it is the range of 8 mass% or less, it is especially preferable.

  As a method for reducing the monomer compound and oligomer compound in the nylon resin, there are a method for controlling the temperature, moisture content, raw material / product concentration in the reaction system of the nylon resin, and nylon after polymerization. Known techniques such as a method of supplying a resin to a hot water extraction tower and counter-current extraction with hot water, and a method of removing a molten nylon resin under a high temperature and a high vacuum can be used.

  As a nylon resin having a total content of the monomer compound and oligomer compound as described above of 1.3% by mass or less, for example, in nylon 12, Daiamide-L1600, L1640 (trade name), nylon 11 manufactured by Daicel-Evonik Then, Rilsan BMF-0 (trade name) of Arkema Co., etc. may be mentioned.

[Protective coating layer]
As shown in FIG. 2, the POF cable of the present invention may be provided with a protective coating layer 104 described below between the POF strand 101 and the light shielding coating layer 102. By providing this protective coating layer, the transfer of the monomer compound and / or oligomer compound derived from the raw material contained in a small amount in the nylon resin forming the above-described light blocking coating layer to the POF strand is blocked. By suppressing the increase in scattering, it is possible to further reduce the increase in transmission loss at wavelengths of 500 nm to 600 nm.

  Examples of the resin for forming such a protective coating layer include polybutylene terephthalate resin, (meth) methyl acrylate resin, styrene resin, vinylidene fluoride homopolymer, copolymer containing ethylene unit and vinyl alcohol unit. Resins selected from coalescence are preferred.

  Hereinafter, various resins that can be preferably used as a material for the protective coating layer of the POF cable of the present invention will be described.

  As the (meth) methyl acrylate resin constituting the protective coating layer, known resins can be used. For example, a homopolymer of methyl (meth) acrylate (such as PMMA) or methyl (meth) acrylate (MMA) Etc.) and other monomers. The content of methyl (meth) acrylate units in the methyl (meth) acrylate resin is preferably 10% by mass or more, more preferably 50% by mass or more, and further preferably 60% by mass or more.

As copolymerization components for methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, tert-butyl (meth) acrylate, (meth) acrylic acid n-Butyl, other (meth) acrylic acid alkyl esters, and the following general formula (9)
_{CH 2 = CX-COO (CH} 2) m (CF 2) nY (9)
(In the formula, X represents a hydrogen atom or a methyl group, Y represents a hydrogen atom or a fluorine atom, m represents 1 or 2, and n represents an integer of 1 to 12.)
(Meth) acrylic acid fluorinated alkyl ester represented by

  In the above general formula (9), if the structure of the fluorinated alkyl group becomes bulky, the polymerization property at the time of copolymerization and the heat resistance of the copolymer are lowered. Therefore, the fluorinated alkyl group has 1 to 12 carbon atoms. It is preferable that

  The (meth) acrylic acid fluorinated alkyl ester represented by the general formula (9) includes (meth) acrylic acid-2,2,2-trifluoroethyl (3FM), (meth) acrylic acid-2,2 , 3,3-tetrafluoropropyl (4FM), (meth) acrylic acid-2,2,3,3,3-pentafluoropropyl (5FM), (meth) acrylic acid-2,2,3,4,4 , 4-Hexafluorobutyl (6FM), (meth) acrylic acid-1H, 1H, 5H-octafluoropentyl (8FM), (meth) acrylic acid-2- (perfluorobutyl) ethyl (9FM), (meth) Acrylic acid-2- (perfluorohexyl) ethyl (13FM), (meth) acrylic acid-1H, 1H, 9H-hexadecafluorononyl (16FM), (meth) acrylic acid-2- ( -Fluorooctyl) ethyl (17FM), (meth) acrylic acid-1H, 1H, 11H- (icosafluoroundecyl) (20FM), (meth) acrylic acid-2- (perfluorodecyl) ethyl (21FM), etc. (Meth) acrylic acid fluorinated ester and the like.

  (Meth) methyl acrylate resin is (meth) from the viewpoint of mechanical strength as a protective coating layer and the dissolution and diffusion of monomers and oligomers contained in the above-mentioned nylon resin into POF strands. A copolymer containing 70 to 95% by mass of methyl acrylate units and 5 to 30% by mass of (meth) acrylic acid alkyl ester units (n-butyl (meth) acrylate or ethyl (meth) acrylate); ) A copolymer containing 60 to 90% by mass of methyl acrylate units and 10 to 40% by mass of (meth) acrylic acid fluorinated alkyl ester units is preferred.

  Further, the methyl (meth) acrylate resin constituting the protective coating layer preferably has a glass transition temperature of 70 ° C. or higher, measured by a differential scanning calorimeter (DSC), of 80 ° C. or higher. Is more preferable, and it is more preferable that it is 90 degreeC or more. If the glass transition temperature is too low, the effect of blocking the transfer of the monomer compound and / or oligomer compound derived from the nylon resin of the light blocking coating layer to the POF strand becomes insufficient.

  A styrenic resin may be used as the resin constituting the protective coating layer. Here, the styrene resin refers to a resin containing 80% by mass or more of styrene units in the resin, and examples thereof include styrene homopolymers and copolymers containing 80% by mass or more of styrene units. As the styrene homopolymer, atactic polystyrene is preferred. Atactic polystyrene is an amorphous polymer having a glass transition temperature around 100 ° C., and has a clear melting point, so it has a relatively low temperature (220 ° C. or lower) and a POF strand having PMMA as a core. It is possible to coat directly. On the other hand, isotactic polystyrene and syndiotactic polystyrene have a melting point of 240 ° C. or higher, and a high coating temperature (260 ° C. or higher) is required when a protective coating layer is coated on the outer periphery of the POF strand. It is preferable that the coating temperature is lower because the influence on the POF strand can be suppressed. In addition, as a copolymerization component with respect to styrene, the various monomer components mentioned as a copolymerization component with respect to the methyl (meth) acrylate mentioned above can be used.

  Examples of such styrenic resins include HF10, NF20, HT52, HF77, 679 (trade name) manufactured by PS Japan, Japan Polystyrene G120K, G440K, G430 (trade name) manufactured by Nippon Polystyrene. You can choose.

  When a vinylidene fluoride resin is used as the resin constituting the protective coating layer, it must be a resin consisting only of vinylidene fluoride (VdF) units (vinylidene fluoride homopolymer: PVDF). Commercially available vinylidene fluoride resins include copolymers containing VdF units, TFE units, HFP units, FVE units (fluorovinyl ether units), etc., and these materials are used as protective coating layers. Even if it uses, the sufficient heat resistance improvement effect of a POF cable cannot be acquired.

  Examples of such PVDF resins include KYNAR710 and 720 (trade name) manufactured by Arkema, HYLAR-MP10 and MP20 (trade name) manufactured by Augmont, and KF polymer (trade name) manufactured by Kureha Chemical Co., Ltd. You can choose from.

  The protective coating layer formed from the resin described above has a sufficient function of blocking the transfer of the monomer compound and / or oligomer compound derived from the nylon resin constituting the light blocking coating layer to the POF strand. In addition, since the POF cable having such a protective coating layer has low adhesion (pullout strength) between the POF strand and the light blocking coating layer, the light blocking coating layer can be easily removed. Therefore, these POF cables can be used for the purpose of peeling a part of the light shielding coating layer from the end portion of the POF cable and fixing the plug thereon.

  On the other hand, in some POF cables for mounting on automobiles, the light shielding coating layer of the POF cable is directly connected to the plug using an adhesive or a laser fusion method without peeling off the light shielding coating layer at the end portion from the POF cable. In this case, strong adhesion (pullout strength) is required between the POF strand and the light shielding coating layer.

  A polybutylene terephthalate resin is preferable as the protective coating layer material capable of exhibiting such strong adhesion.

  The polybutylene terephthalate resin (hereinafter abbreviated as PBT resin) constituting the protective coating layer is an esterification reaction of 1,4-butanediol (tetramethylene glycol) and terephthalic acid, or 1,4 butanediol and terephthalate. Bishydroxybutyl terephthalate (BHT) obtained by transesterification of dimethyl acid or an oligomer thereof synthesized by polycondensation is represented by the following general formula (10)

The polymer which contains the unit of the oligo poly 1, 4- butylene terephthalate shown by this as a main structural unit.

  More specifically, the PBT resin suitable for the present invention contains oligopoly 1,4-butylene terephthalate represented by the above general formula (10) as a hard segment unit (crystalline phase), and a soft segment unit (amorphous). Phase) as an aliphatic polyether having a molecular weight in the range of 200 to 5000 (for example, polytetramethylene glycol (PTMG)), terephthalic acid, dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, and dibutyl terephthalate. The following general formula (11) synthesized by polycondensation with at least one of them

(In the formula, p represents an integer of 4 to 12, and q represents an integer of 2 to 20.)
The PBT resin which is a block copolymer containing the block unit containing an aliphatic polyether unit shown by these is mentioned.

  Alternatively, the oligopoly 1,4-butylene terephthalate represented by the above general formula (10) is contained as a hard segment unit (crystalline phase), and poly (ε-caprolactone) (PCL) or poly (poly) as a soft segment unit (amorphous phase). The following general formula (12), such as butylene adipate (PBA)

The PBT resin which consists of a block copolymer containing the block unit of the aliphatic polyester shown by these is mentioned.

  Among the above PBT resins, the aliphatic polyether unit represented by the above general formula (11) is particularly preferable in that the durability of the optical performance of the POF cable and the pull-out strength of the coating layer is maintained under high temperature and high humidity. A PBT resin having a block unit as a soft segment unit is preferable. In particular, a hard segment part (A) composed of oligopoly 1,4-butylene terephthalate (structure represented by formula (10)) and terephthalic acid or terephthalate and polytetramethylene glycol (PTMG) having a molecular weight in the range of 200 to 600 PBT resin, which is a block copolymer containing a soft segment part (B) composed of a polycondensate with (a structure in the case of p = 4 in the formula (11)), is an optical fiber for POF cables under high temperature and high humidity. It is preferable because of its excellent performance and durability of the pulling strength of the coating layer.

  Further, in the PBT resin, the total number of moles (a) of 1,4-butylene terephthalate units contained in the hard segment part (A) and 1,4-butylene terephthalate units contained in the soft segment part (B). The ratio (a / b) of the total number of moles (b) is preferably in the range of 15/85 to 30/70. If this ratio (a / b) is too small, the number of ether bond units in the polymer main chain will increase, so that the PBT resin will be susceptible to degradation due to hydrolysis under high temperature and high humidity, and the soft segment content will increase. Therefore, since the material itself is flexible and easily deformed, the pulling strength is reduced, and the effect of blocking the monomer or oligomer derived from the nylon resin constituting the light blocking coating layer is reduced. Conversely, if this ratio (a / b) is too large, the hard segment content increases, so the melting point increases, the coating stability of the protective coating layer decreases, and the POF strands in the coating process There exists a tendency for the heat-sealing property between a protective coating layer and / or between a protective coating layer and a light-shielding coating layer to fall. The ratio (a / b) is more preferably 18/82 or more, and further preferably 22/78 or more. On the other hand, this ratio is more preferably 27/73 or less, and further preferably 25/75 or less.

  Furthermore, the melting point of the PBT resin is preferably in the range of 155 ° C. or higher and 205 ° C. or lower. If the melting point is too low, the function of blocking the transfer of monomers and oligomers to the POF strands may be insufficient. On the other hand, if the melting point is too high, there is a risk that the molding stability when a protective coating layer is provided on the outer periphery of the POF strand using a coextrusion coating apparatus as will be described later is lowered. The melting point of the PBT resin is more preferably 195 ° C. or less, and further preferably 185 ° C. or less. The melting point of the PBT resin is more preferably 165 ° C. or higher, and further preferably 175 ° C. or higher.

  Further, the PBT resin preferably has a Shore D hardness of 38 to 65 measured according to JIS K7215 standard. If the Shore D hardness is too low, the fluidity at high temperatures tends to increase, so that the coating stability tends to decrease, and the material itself tends to be flexible and easily deformed. The pull-out strength between the barrier coating layer decreases. If the Shore D hardness is too high, the thermal fusion between the POF strand and the protective coating layer and / or between the protective coating layer and the light shielding coating layer in the coating process is reduced. The pull-out strength between the barrier coating layer decreases. The Shore D hardness is more preferably 40 or more, and further preferably 45 or more. The Shore D hardness is more preferably 60 or less, and even more preferably 55 or less.

  The melting point and Shore D hardness of such a PBT resin can be adjusted by adjusting the composition ratio of the hard segment unit and the soft segment unit, the molecular weight of each, or the molecular weight of the entire polymer.

  Examples of such PBT resins include Hytrel 2551, 2474, 4047, 4057, 4767 (trade name) manufactured by Toray DuPont, DYURANEX 400LP (trade name) manufactured by Polyplastics, and Teijin Chemicals Ltd. It can be selected from Nouvelan 4400 series (trade name) manufactured by Toyobo Co., Ltd., Perprene S type, P type (P150M) (trade name) manufactured by Toyobo Co., Ltd., and Primalloy B series (trade name) manufactured by Mitsubishi Chemical Corporation.

  By using the PBT resin as described above for the protective coating layer, it becomes possible to increase the pull-out strength between the POF strand and the light shielding coating layer to 30 N or more, and when the POF cable is placed in a high temperature environment. The occurrence of pistoning can be further suppressed. In addition, when the plug is fixed to one end of the POF cable and connected to other devices through the plug and then subjected to mechanical action such as vibration, the adhesion between the POF strand and the light shielding coating layer is poor. When sufficient, an excessive force acts on the POF strand and the POF strand is easily broken, but such breakage can be prevented.

  In addition, as a resin constituting the protective coating layer capable of exhibiting a strong adhesion effect, there is a copolymer containing ethylene units and vinyl alcohol units (hereinafter abbreviated as EVAL copolymer). This EVAL copolymer is preferably a copolymer in which the content ratio of ethylene units to vinyl alcohol units is in the range of 20 to 70 mol% ethylene units and 30 to 80 mol% vinyl alcohol units. In particular, the copolymer has a melting point of 195 ° C. or lower, more preferably 180 ° C. or lower, and a melt flow index measured at 210 ° C. and a load of 5 kgf (49 N) in a range of 25 to 80 g / 10 minutes. The monomer and oligomer contained in the above-mentioned nylon resin are preferable because they are excellent in the effect of preventing dissolution and diffusion into the POF strand and are excellent in the molding stability of the POF cable.

  Further, since the EVAL copolymer has a high oxygen barrier property, it is possible to suppress an increase in transmission loss due to oxidation degradation of POF in a high temperature environment.

  Examples of the EVAL copolymer include Eval E105, G156, F104, FP104, EP105, EU105 (trade name) manufactured by Kuraray Co., Ltd., and the like.

  Various resins as described above can be mentioned as preferred materials for forming the protective coating layer of the POF cable of the present invention. In order to prevent the outside light from entering the POF strand, Similarly to the light shielding coating layer, a light shielding agent such as carbon black may be contained, and in order to obtain a sufficient light shielding effect, the protective coating layer has an intrinsic effect of, for example, 0. You may contain 1 mass% or more.

[Functional coating layer]
One of the features of the POF cable of the present invention is that a functional coating layer made of a nylon resin composition having an oxygen transmission rate in a specific range is provided on the outer periphery of the light shielding coating layer so that the POF cable can be used in a high temperature environment. It is to suppress an increase in electronic transition absorption when used in the above. By making this functional coating layer contain a brominated polymer flame retardant described later, it is possible to impart flame retardancy and to further improve heat resistance. In addition, by including an inorganic pigment described later in this functional coating layer, it is possible to impart distinguishability to the POF cable without impairing the heat resistance, and in some cases, the heat resistance can be further improved.

  The above-mentioned POF cable (primary coated cable) in which a light shielding coating layer or a protective coating layer and a light shielding coating layer are formed on the outer periphery of the POF strand described above has the following heat resistance in a 105 ° C. environment. It is insufficient. If only the transmission loss in the vicinity of the wavelength of 650 nm is observed, it is stable for a long time even in the environment of 105 ° C., but the increase in the POF transmission loss is large in the wavelength region shorter than 600 nm, and in the wavelength region of 500 to 600 nm. It was difficult to use for signal transmission.

  On the other hand, in a POF cable used in an in-vehicle LAN or the like, a nylon-based resin composition colored on the outer periphery of the light shielding coating layer of the primary coated cable for further identification in order to enhance discrimination and flame retardancy. It is required to form a functional coating layer made of

  As described above, since the polymerization of the nylon resin is a chemical equilibrium reaction, it is inevitable that monomers and oligomers derived from the nylon resin raw material remain in the polymer. Furthermore, according to the examination results of the present inventors, a POF cable in which a certain type of nylon resin is provided as a functional coating layer on the outer periphery of a primary coated cable that is excellent in durability at a high temperature environment of 105 ° C. When left in a high temperature environment of 105 ° C. for a long time, oxygen in the environment where the POF cable is placed and residual monomers and oligomers in the functional coating layer pass through the light shielding coating layer and the protective coating layer. It has been found that it dissolves and diffuses inside the POF strand, causing an increase in electronic transition absorption, Rayleigh scattering, and the like, resulting in an increase in POF transmission loss.

  Therefore, as a result of intensive studies on a nylon resin composition that does not impair the heat resistance of a POF cable (primary coated cable) even when used in a functional coating layer, the present inventors have determined the crystalline melting point and oxygen permeability. It has been found that by using a nylon resin composition in the range of <1>, an increase in transmission loss at a wavelength of 600 nm or less can be remarkably suppressed without impairing transmission characteristics at a wavelength of 650 nm in a high temperature environment of 105 ° C.

That is, as a nylon-based resin composition for forming this functional coating layer, the crystal melting point by differential scanning calorimetry (DSC) is 240 ° C. or higher and 280 ° C. or lower, and is defined in ISO 14663-2: 1999 (Annex C). The oxygen permeability P (cm ³ · cm / (cm ² · sec · Pa)) at the temperature T (K) measured by the method is represented by the following general formula (1)
P <8 × 10 ⁻² × exp (−5600 / T) (1)
A nylon resin composition satisfying the above is used.

  In addition, the range of temperature T (K) where General formula (1) is materialized here is 283K (10 degreeC) or more and 333K (60 degreeC) or less. It is well known that the oxygen permeability of a polymer material has Arrhenius dependence on temperature, and the Arrhenius dependence changes before and after the glass transition temperature. The glass transition temperature of the nylon 66 resin composition in the present invention is in the range of 55 to 65 ° C. Therefore, the upper limit of the temperature T (K) is 333K (60 ° C.). On the other hand, the lower limit is 283 K (10 ° C.) or more from the viewpoint of measurement accuracy of oxygen permeability.

  As such a nylon resin composition, a nylon resin composition mainly composed of nylon 66 is preferable from the viewpoint of obtaining a higher heat resistance improvement effect (particularly, a wavelength of 600 nm or less), and in particular, its oxygen permeability ( P) preferably satisfies any condition obtained by substituting T = 296K (23 ° C.) into general formula (1) and general formulas (2) to (4) described later.

  First, the necessity for the crystalline melting point of the nylon resin composition forming the functional coating layer to be 240 ° C. or higher and 280 ° C. or lower will be described.

  It is known that a temperature called a Brill transition temperature exists in a nylon resin. At this Brill transition temperature, the phenomenon called the Brill transition, that is, the torsional motion between the methylene-amide groups of the polymer main chain becomes active, and the hydrogen bonds of the amide groups are maintained, but the conformational fluctuations and regularity of the methylene chains are maintained. A phenomenon in which a large movement with disturbance starts to occur (Polymer, 44 (2003), p6407-6417).

  The Brill transition phenomenon is a phenomenon that occurs over a temperature range of about 40 ° C., and the temperature of the peak maximum value is called the Brill transition temperature. Nylon 12 (melting point: about 180 ° C.) has a Brill transition temperature of about 140 to 150 ° C., and nylon 6-12 (melting point: about 155 to 160 ° C.) has a Brill transition temperature of about 120 to 130 ° C. ing. According to the study by the present inventors, when a nylon resin composition containing nylon 12 or nylon 6-12 is used as a material for the functional coating layer, the POF cable is left in an environment of 100 ° C. for a long period of time. In this case, it has been found that the residual monomer or residual oligomer derived from the nylon resin contained in nylon 12 or nylon 6-12 migrates into the POF strand, and the optical transmission performance is significantly reduced. In these nylon 12 and nylon 6-12, since the Brill transition temperature exists in the vicinity of about 120 to 145 ° C., it is considered that bleeding of residual monomers and residual oligomers easily occurs, and has a higher Brill transition temperature. It was thought that this problem could be improved if a nylon resin composition was used as the material for the functional coating layer.

  However, the Brill transition temperature is not an index value that can be easily measured because a special apparatus is used for the measurement. Therefore, the present inventors examined the use of a crystal melting temperature (crystal melting point) measured by a differential operation calorimeter (DSC) as an index value that can be measured relatively easily. As a result, it was found that by setting the crystal melting point of the nylon resin composition used for the functional coating layer in a certain temperature range, the durability performance of the POF cable can be made sufficient, and the present invention was completed. .

  That is, if the crystalline melting point of the nylon resin composition constituting the functional coating layer is lower than 240 ° C., the raw material of the nylon resin constituting the functional coating layer when the POF cable is placed in an environment of 105 ° C. for a long period of time. There is a possibility that the phenomenon that the residual monomer or oligomer derived from bleed out from the functional coating layer and migrate to the POF strand cannot be suppressed. On the other hand, if the crystal melting point is higher than 280 ° C., the temperature at which the functional coating layer is formed must be set high. Therefore, when the crystal melting point is set at 300 ° C. or more, the core is made of a copolymer mainly composed of PMMA or MMA. Light-shielding coating layer made of a nylon resin having a relatively low melting point such as nylon 11 and nylon 12 is likely to be thermally deformed, and the optical characteristics and heat shrink characteristics of the POF cable may be impaired. is there. The crystalline melting point of the nylon resin composition constituting the functional coating layer is preferably 240 ° C. or higher, more preferably 250 ° C. or higher, and further preferably 260 ° C. or higher. The crystal melting point is preferably 280 ° C or lower, more preferably 275 ° C or lower, and further preferably 270 ° C or lower.

  As the nylon resin contained in the nylon resin composition having a crystal melting point of 240 ° C. or higher and 280 ° C. or lower, specifically, a homopolymer of nylon 66 or nylon 66 as described below is a main component. Mention may be made of nylon resin compositions. Here, the main component means that when the total amount of the nylon resin composition is 100% by mass, it means that nylon 66 is contained by 50% by mass or more, preferably 60% by mass or more, and preferably 70% by mass or more. Is more preferable.

Nylon 66 (Brill temperature has a maximum value of about 150 to 160 ° C., Polymer, 42 (2001), p10119-10132) has a melting point of 265 ° C., and the oxygen permeability at a temperature of 23 ° C. is P = about 3 × 10 ⁻¹⁰ to 4 × 10 ⁻¹⁰ cm ³ · cm / (cm ² · sec · Pa), the oxygen permeability at a temperature of 105 ° C. is P = about 1 × 10 ⁻⁸ to 2 × 10 ⁻⁸ cm ³ · cm / (Cm ² · sec · Pa).

  As for the total content of the monomer compound and oligomer compound derived from the nylon resin contained in the functional coating layer, the POF cable according to the present invention has sufficient heat resistance as long as it is at the level of nylon resin that is generally industrialized. Can be obtained. The total content of the monomer compound and oligomer compound in the functional coating layer is preferably in the range of 15% by mass or less, more preferably in the range of 10% by mass or less, and in the range of 5.0% by mass or less. Is particularly preferred. There is no particular limitation on the lower limit of the total content of these compounds. When the total content of the monomer compound and oligomer compound in the functional coating layer is within the above range, a POF cable having more sufficient heat resistance can be obtained. For example, a POF cable having sufficient heat resistance can be obtained even if the total content of the monomer compound and oligomer compound in the functional coating layer is 0.1% by mass or more, further 0.5% by mass or more. .

  The monomer compound and oligomer compound derived from the nylon resin are as described above. Specifically, in the case of nylon 66, the monomer is hexamethylenediamine and adipic acid, and the oligomer is hexamethylenediamine and adipine. It means a cyclic oligomer or a chain oligomer having a tetramer or less of a condensation compound composed of an acid.

  As nylon 66, UBE nylon 2015B, 2020B, 2026B (trade name) manufactured by Ube Industries, Ltd., Amilan CM3007, CM3001-N, CM3006, CM3301, CM3304, CM3004 (trade name) manufactured by Toray Industries, Inc., manufactured by Asahi Kasei Chemicals Corporation Leona 1200S, 1300S, 1500, 1700 (trade name), Ultramid 1000, 1003, A3, N322, A3X2G5 (trade name) manufactured by BASF, GRILON AS series, AZ series, AR, manufactured by EMS / CHEMIE AG The AT series (trade name) and Zytel 101, 103, 42A, and 408 (trade name) manufactured by DuPont can be mentioned.

  The transmission loss value of the POF cable described above at a wavelength of 650 nm is stable for a long period of time even under a high temperature environment of 105 ° C.

  Next, the oxygen permeability (P) of the nylon resin composition forming the functional coating layer will be further described.

  When the oxygen permeability (P) of the nylon resin composition forming the functional coating layer is higher than the value on the right side of the above formula (1), when the POF cable is placed in a high temperature environment of 105 ° C. for a long time, Oxygen in the environment where the POF is placed passes through the light shielding coating layer and the protective coating layer, dissolves and diffuses inside the POF strand, and the tendency of the POF strand to undergo oxidative degradation increases. As a result, the electronic transition absorption in the core part and the clad part of the POF strand increases, and the transmission loss at a wavelength of 600 nm or less increases. If the oxygen transmission rate (P) satisfies the above formula (1), an increase in transmission loss of POF wavelength of 600 nm or less can be suppressed.

The oxygen permeability (P) of the nylon resin composition forming the functional coating layer is represented by the following general formula (2) from the viewpoint of suppressing an increase in transmission loss at a wavelength of 600 nm or less.
P <8 × 10 ⁻² × exp (−5800 / T) (2)
More preferably,
The following general formula (3)
P <8 × 10 ⁻² × exp (−6000 / T) (3)
More preferably,
The following general formula (4)
P <8 × 10 ⁻² × exp (−6300 / T) (4)
It is particularly preferable to satisfy

  As a method for lowering the oxygen permeability of the nylon resin composition, it is preferable to use a method for controlling the crystallinity within a certain range or a method for controlling the spherulite size within a certain range.

  The crystallinity of the nylon resin composition forming the functional coating layer is preferably in the range of 30% to 55%. By controlling the crystallinity in such a range, a nylon resin composition having a desired oxygen permeability can be easily obtained. If the degree of crystallinity is too small, post-crystallization occurs when the POF cable is processed at a high temperature, so that the dimensional change of the POF cable occurs or the desired oxygen permeability cannot be obtained. When placed in an environment for a long time, it may be difficult to suppress an increase in transmission loss at a wavelength of 600 nm or less. If the degree of crystallinity is too high, the flexural modulus of the POF cable will increase, making it difficult to handle the POF cable, and if the POF cable is wound around a bobbin and stored for a long period of time, it will be prone to wrinkles. Such problems arise. The lower limit side of the preferred range of the crystallinity of the nylon-based resin composition forming the functional coating layer is more preferably 35% or more, the upper limit side is more preferably 50% or less, and further preferably 45% or less.

  The crystallinity (X) is calculated from the density according to the following general formula.

Crystallinity (X) = (ds−da) / (dc−da)
(Da: amorphous density, dc: crystalline density, ds: sample density).

  In the present invention, the nylon resin composition forming the functional coating layer preferably has an average diameter of spherulite size by microscopic observation in the range of 0.01 μm or more and 40 μm or less.

  Here, the spherulite size is obtained by preparing an ultrathin section from the functional coating layer of the POF cable, observing the section with a microscope, taking a photograph of the spherulite, and then taking the number average of the diameter of the spherulite with an image analyzer. Is a value obtained by calculating.

  If the spherulite size is too small, the mechanical strength (particularly, tensile strength) of the POF cable tends to decrease. If the spherulite size is too large, the desired oxygen transmission rate cannot be obtained. Therefore, when the POF cable is placed in an environment of 105 ° C. for a long period of time, the transmission loss at a wavelength of 600 nm or less increases, or the POF cable. There is a tendency that the heat-resistant dimensional stability is impaired. The lower limit side of the preferred range of the spherulite size (average diameter) is more preferably 1.0 μm or more, further preferably 5 μm or more, and the upper limit side is more preferably 30 μm or less, further preferably 20 μm or less, and particularly preferably 10 μm or less.

  Examples of a method for controlling the crystallinity and spherulite size of a nylon-based resin such as nylon 66 within a certain range include a method for controlling a molding temperature, a cooling rate, and the like during production to an appropriate range. . However, it is difficult to control to a desired crystallinity and spherulite size within the range of conditions that can be manufactured without impairing the performance of the POF cable. Therefore, in the POF cable of the present invention, it is preferable that the nylon resin composition forming the functional coating layer contains a crystallization accelerator (nucleating agent) or a specific flame retardant described later. The size can be reduced and the crystallinity can be increased.

  As the crystallization accelerator, a compound that migrates into the POF strand and does not affect the optical performance of the POF cable is preferable. Examples of such crystallization accelerators include metal oxides such as magnesium oxide, aluminum oxide, zinc oxide, copper oxide and iron oxide, inorganic fine particles such as talc, silica, graphite and silicon carbide, nylon 6T, nylon 66 / Although high melting point polyamides, such as 6T, can be mentioned, it is not limited to these.

  The content of the crystallization accelerator in the nylon resin composition forming the functional coating layer can be appropriately set within a range that does not impair the heat resistance of the POF cable at 105 ° C., but the nylon resin composition 100 It is preferable that it exists in the range of 0.01-10 mass% with respect to the mass%, The range of 0.05-5 mass% is more preferable, The range of 0.3-3 mass% is further more preferable.

[Flame retardant for functional coating layer]
By incorporating a specific flame retardant into the nylon resin composition forming the functional coating layer, the oxygen permeability of the functional coating layer can be reduced.

  Since high flame retardance is required for POF cables used for in-car communication applications, it is preferable to include a flame retardant in the functional coating layer. When the functional coating layer contains a flame retardant, it is preferable that the POF cable of the present invention does not contain a flame retardant in the POF strand made of PMMA resin, the protective coating layer, and the light shielding coating layer. Since the material of the coating layer does not have self-extinguishing properties, the functional coating layer preferably has a flame retardant function.

  As flame retardants generally used for nylon resins, phosphorus compounds, bromine compounds, chlorine compounds, triazine compounds, and hydrated metal compounds are well known and are used in various applications. .

  However, according to the study by the present inventors, certain flame retardants pass through the light shielding coating layer and the protective coating layer when the POF cable is placed in a high temperature environment of 105 ° C. for a long time. Since it moves to the strand part, it causes a significant increase in transmission loss, causes deterioration of the coating material itself, or requires a considerably high blending amount to achieve sufficient flame retardancy. It has been found that the mechanical strength of is significantly reduced.

  As a result of searching and examining a flame retardant capable of solving such problems, the present inventors have found that a high molecular weight type brominated flame retardant (brominated polymeric flame retardant) is used alone or a high molecular weight type brominated flame retardant. It has been found that it is optimum for the POF cable of the present invention to use a flame retardant and antimony oxide in combination and add an amount within a specific range to the nylon resin.

  That is, when the total amount of the nylon resin composition constituting the functional coating layer is 100% by mass, the bromine flame retardant is an amount in which the bromine atom content in the resin composition is in the range of 1.5 to 30% by mass. , And antimony oxide are preferably contained in an amount ranging from 0 to 20% by mass. If the bromine atom content is too small, it is difficult to impart sufficient flame retardancy to the POF cable. If the bromine atom content is too large, the wear resistance and mechanical strength of the POF cable will decrease, or the POF cable will be bent. There is a possibility that the elastic modulus becomes too high and the handleability is lowered. The bromine atom content is more preferably 5% by mass or more, further preferably 8% by mass or more, and particularly preferably 10% by mass or more. The bromine atom content is more preferably 25% by mass or less, further preferably 20% by mass or less, and particularly preferably 15% by mass or less.

  Among such brominated flame retardants, polystyrene brominated products having a number average molecular weight in the range of 900 to 60,000, brominated polystyrene (brominated polystyrene) such as polydibromostyrene, and poly (pentabromobenzyl acrylate). At least one selected is particularly preferred. In addition, a number average molecular weight (Mn) means Mn of the polystyrene conversion molecular weight measured by gel permeation chromatography (GPC) here.

  If the molecular weight of the brominated flame retardant is too small, the brominated flame retardant may be used when the POF cable is placed in a high temperature environment at 105 ° C. for a long time, even if the material of the functional coating layer has a high melting point as described above. Bleeds out from the functional coating layer, passes through the light shielding coating layer and the protective coating layer, and shifts to POF strands, causing a significant increase in transmission loss, or bromine on the surface of the functional coating layer of the POF cable. The flame retardant of the type may bleed out and the flame retardancy of the POF cable may decrease.

  If the molecular weight of the brominated flame retardant is too large, the fluidity of the brominated flame retardant and the solubility / dispersibility in the nylon resin composition will decrease, resulting in the flame retardancy and mechanical strength of the POF cable. Tends to decrease or the appearance of the cable is impaired.

  As polystyrene bromide (BrPS) or polydibromostyrene (PDBS), the following general formula (17)

(M = 2 for polydibromostyrene, m = 2 to 5 for polystyrene bromide, n is an integer)
The compound of molecular weight 900-60,000 shown by can be mentioned. For example, FR-803P (trade name) manufactured by Bromochem, SAYTEX-HP-7010, HP-3010, PYROCHEK-68PB (trade name) manufactured by Albemarle, PB-411, PBDS-80, PBS- manufactured by GLC 64HW, CP-411 (trade name), and Manufactured plastic safety-1200 (trade name).

  Even if it uses a brominated flame retardant alone, the improvement effect of a flame retardance will be acquired, but a flame retardance can be improved further by using together with an antimony oxide. Antimony oxide is suitable for the POF cable of the present invention because it does not shift to a POF strand even when the POF cable is placed in a high temperature environment for a long period of time. Examples of such antimony oxide include antimony trioxide and antimony pentoxide, but antimony pentoxide is preferred from the viewpoint of low cost. The content of antimony oxide is a brominated flame retardant in an amount such that the bromine atom content is in the range of 1.5 to 30% by mass when the entire nylon resin composition constituting the functional coating layer is 100% by mass. On the other hand, it is preferable to add antimony oxide so that it may become 20 mass% or less. If the content of antimony oxide is too large, the wear resistance and mechanical strength of the POF cable may be reduced, or the bending elastic modulus of the POF cable may be too high and the handleability may be reduced. The content of antimony oxide is more preferably 15% by mass or less, and further preferably 10% by mass or less. When a brominated flame retardant and antimony oxide are used in combination, the mass ratio of brominated flame retardant to antimony oxide (brominated flame retardant / antimony oxide) should be in the range of 1/1 to 4/1. It is preferable to set. If this mass ratio is too high, the synergistic effect of flame retardancy due to the addition of antimony oxide is insufficient, and if this mass ratio is too low, excessive antimony oxide is added, resulting in flame retardancy. However, there is a possibility that the wear resistance and mechanical strength of the POF cable are lowered, or the bending elastic modulus of the POF cable is increased. The mass ratio between the brominated flame retardant and antimony oxide is more preferably 1.5 / 1 or more, and further preferably 2/1 or more. Further, this mass ratio is more preferably 3/1 or less, and further preferably 2.5 / 1 or less.

  Antimony trioxide can include PATOX series (CZ, etc.) manufactured by Nippon Seiko Co., Ltd., STOX series (trade name), FCP AT-3, AT-3CN (trade name) manufactured by Suzuhiro Chemical Co., Ltd., etc. Examples of antimony pentoxide include San Epoch (trade name) manufactured by Nissan Chemical Co., Ltd.

[Colorant for functional coating layer]
In the POF cable of the present invention, by adding a specific colorant to the nylon resin composition forming the functional coating layer, or by adding a combination of the above-mentioned flame retardant and the specific colorant, The oxygen permeability can be controlled by increasing the crystallinity of the material or reducing the spherulite size. As a result, when the POF cable is used in a high temperature environment, not only can the transmission characteristics at a wavelength of 650 nm be stably maintained, but an increase in transmission loss at a wavelength of 600 nm or less can be remarkably suppressed.

  Organic pigments and inorganic pigments are widely used as colorants for general thermoplastic resins, but chromatic inorganic pigments are used as colorants for identifying functional coating layers.

  According to the study by the present inventors, when a POF cable containing an organic dye in the functional coating layer is placed in a high temperature environment at 105 ° C. for a long time, these organic dyes are protected from the light blocking coating layer. It has been found that it moves through the coating layer into the POF strand, causing a significant increase in transmission loss. On the other hand, when an inorganic pigment is used, such a transition phenomenon is not observed, and it is clear that even if the POF cable is placed in a high temperature environment of 105 ° C. for a long time, the transmission loss is not affected. I made it.

  The content of the inorganic pigment is preferably in the range of 0.1% by mass or more and 10% by mass or less when the entire nylon resin composition constituting the functional coating layer is 100% by mass. If the content of the inorganic pigment is too small, the coloring effect is insufficient and it becomes difficult to produce a vivid color. If the content is too large, the mechanical strength of the covering material is lowered, and the wear resistance and the scratch resistance may be lowered. The content of the inorganic pigment is more preferably 0.5% by mass or more, further preferably 1% by mass or more, and particularly preferably 3% by mass or more. Further, the content of the inorganic pigment is more preferably 7% by mass or less, and further preferably 5% by mass or less.

  As an inorganic pigment, for example, when a green color is required, a rare metal compound containing at least one of cerium or lanthanum, when blue, ultramarine blue, bitumen, when yellow, yellow iron oxide, when red In the case of a petal (diiron trioxide), white, titanium oxide, talc, kaolin, and black, carbon black, black iron oxide and the like can be mentioned. Among these, at least one colorant selected from ultramarine, bitumen, iron oxide, dial, titanium oxide, rare metal compound, and carbon black can be preferably used.

[PoF cable structure]
Next, the thickness of each layer constituting the POF cable of the present invention will be described.

  In the present invention, the outer diameter of the POF strand having a core-cladding structure is a (μm), the thickness of the light shielding coating layer (or the combination of the light shielding coating layer and the protective coating layer) is b (μm), When the thickness of the coating layer is c (μm), it is preferable to set the values of a, b, and c within a range satisfying the following formula from the viewpoint of achieving both mechanical characteristics and heat resistance characteristics.

900 ≦ a ≦ 1100
200 ≦ b ≦ 350
500 ≦ b + c ≦ 660
If the thickness b of the light shielding coating layer is too small, the chemical resistance of the POF cable may be reduced. Conversely, if it is too large, residual monomers and oligomers derived from the light shielding coating layer may contribute to the optical properties of the POF strand. May have an effect.

  If the thickness (b + c) of the entire coating layer is too small, the effects of each layer, such as vibration in the automobile and the effect of protecting the POF strand from a hot and humid environment, may be insufficient. On the other hand, if it is too large, the flexural elasticity of the POF cable becomes large, and the handleability during cable processing decreases.

[PoF cable manufacturing method (coating method)]
Next, a method for forming the coating layer of the POF cable of the present invention will be described.

  The covering step in the POF cable manufacturing process of the present invention can be performed by covering the outer periphery of the POF strand with a covering material using an extrusion coating apparatus equipped with a crosshead die.

  In the case of the protective coating layer and the light shielding coating layer, the range of the coating temperature T when coating the POF strand is preferably 190 ° C. or higher and 230 ° C. or lower. When the coating temperature is lower than 190 ° C., the resin to be coated is not sufficiently melted and becomes a lump, resulting in a large fluctuation in the thickness of the coating, or the flow of the coating resin in the coating apparatus piping is deteriorated, resulting in insufficient resin discharge. The desired thickness control becomes difficult. When the coating temperature is higher than 230 ° C., the POF strands are likely to melt, and there is a possibility that the outer diameter fluctuates due to the coating resin supply pressure in the coating process, or the transmission loss increases due to thermal degradation. In order to control the thickness of the coating layer to be thinner and more uniform and maintain the optical characteristics of the POF strand, the coating temperature T is more preferably in the range of 200 ° C. to 220 ° C.

  When covering the functional coating layer, although depending on the main material of the nylon resin composition, when the melting point of the functional coating material is M ° C., it is preferably M + 3 ° C. or higher and M + 15 ° C. or lower. When the coating temperature is lower than M + 3 ° C., the resin to be coated is not sufficiently melted and becomes a lump, resulting in a large fluctuation in the thickness of the coating, and the flow of the coating resin in the coating apparatus piping is deteriorated, resulting in insufficient resin discharge. The desired thickness control becomes difficult. When the coating temperature is higher than M + 15 ° C., the POF strand or the primary coated cable is likely to melt, and there is a possibility that the outer diameter fluctuates due to the coating resin supply pressure in the coating process, or the transmission loss increases due to thermal degradation. . In order to control the thickness of the coating layer thinner and more uniformly and to maintain the optical characteristics of the POF strand, the coating temperature T is more preferably in the range of M + 5 ° C. or higher and M + 10 ° C. or lower.

  The POF strand can be coated as follows.

  First, in accordance with a normal method, a core and at least one or more layers of clad formed on the outer periphery thereof are composite-spun to form a POF strand. After that, a light blocking coating layer is formed on the outer periphery of the POF strand using a coating device equipped with a crosshead die to obtain a POF primary cable. Thereafter, a functional coating layer is formed on the outer periphery of the POF primary cable by using a coating apparatus having another crosshead die.

  When a protective coating layer is provided, the POF strand can be coated according to the following method.

  First, the core, at least one clad formed on the outer periphery thereof, and a protective coating layer formed on the outer periphery thereof are composite-spun to integrally form the POF strand and the protective coating layer. After that, a light shielding coating layer is formed on the outer periphery of the protective coating layer using a coating device equipped with a crosshead die to obtain a POF primary cable. Thereafter, a functional coating layer is formed on the outer periphery of the POF primary cable by using a coating apparatus having another crosshead die.

  Moreover, when providing a coating layer, a POF strand can be coat | covered also with the following method.

  First, a POF strand consisting of a core and at least one clad formed on the outer periphery thereof is formed by composite spinning. After that, using a coating apparatus equipped with a crosshead die, the outer periphery of the POF strand is simultaneously coated with a protective coating layer and a light blocking coating layer by coextrusion to obtain a POF primary cable. Thereafter, a functional coating layer is formed on the outer periphery of the POF primary cable by using a coating apparatus having another crosshead die.

  As the coating apparatus, an apparatus (crosshead die) having a crosshead as shown in FIG. 3 can be used. The POF strand or the POF primary cable passes through a path along the axis 204 provided in the dies 202 and the nipple 202 of the crosshead, and after being covered, the POF cable is opened to the outside from the opening of the front end surface 201a of the die 201. Extruded. At this time, in the cross head, the resin from the coated resin flow path 203 is coated on the outer periphery of the POF strand (or the POF primary cable). It is preferable that the angle θ (the taper angle of the die-nipple) formed by the coating resin flow path 205 and the axis 204 at the die-nipple portion is 20 degrees to 70 degrees. That is, the POF strand (or POF primary cable) and the material forming the coating layer are in contact with each other when the angle between the central axis of the POF strand and the flow direction of the flow path 205 of the coating material is in the range of 20 degrees to 70 degrees. It is preferable to do. If θ is less than 20 degrees, it is difficult to form a coating layer on the POF strand (or POF primary cable) with a uniform thickness, while if it exceeds 70 degrees, the coating material heated to a high temperature. Increases the heat and stress applied to the POF strand, and the optical properties of the POF strand may deteriorate. When forming a light shielding coating layer or a protective coating layer, the angle θ is preferably 30 to 45 degrees, and when forming a functional coating layer, the angle θ is 30 to 60 degrees. It is preferable that it is formed so as to have a degree.

  When the functional coating layer is formed, the nylon resin composition used for the functional coating layer includes, for example, a nylon resin mainly composed of nylon 66 and at least the above-described bromine-based polymer flame retardant (an additional oxidation if necessary). A nylon resin composition containing antimony) and a nylon resin composition containing the inorganic pigment described above are mixed in a non-molten state to form a nylon resin mixture, and this nylon resin mixture is attached to the coating device. It is possible to melt and knead using a conventional extruder to form a molten resin mixture. Immediately thereafter, the molten resin mixture can be introduced into a crosshead die and continuously coated on the outer periphery of the POF strand. .

[Signal transmission method using POF cable]
Next, a signal transmission system using the POF cable of the present invention will be described.

  As described above, visible LEDs having an emission center wavelength in the vicinity of 650 nm are widely used as POF light sources, but have a problem of insufficient heat resistance at 100 ° C. or higher. The reason for this is that such an LED is formed from a GaAlAs-based material and is easily oxidized due to a large proportion of Al components.

  On the other hand, as a visible light LED having an emission center wavelength of 600 nm or less, an InGaN system (emission center wavelengths 505 nm and 520 nm), a PGaN system (emission center wavelength 565 nm), an InGaAlP system (emission center wavelength 590 nm), and the like are known. Although it does not contain Al components that cause the heat resistance of the LED to decrease, or the content is small even if it contains, the heat resistance of the LED itself at 100 ° C or higher has reached a level where it can be practically used. Yes.

  On the other hand, as described above, the POF cable of the present invention has a barrier coating layer and a functional coating layer made of a specific material on the outer peripheral portion of the POF strand, and is made of a specific material as necessary. By further including the protective coating layer, an increase in POF transmission loss is significantly suppressed even in a wavelength region of 600 nm or less in a high temperature environment of 100 ° C. or higher.

  Thus, by combining the POF cable of the present invention and a visible light LED having a light emission center in a wavelength range of 500 nm or more and 600 nm or less, a field where long-term heat resistance at 100 ° C. or higher is required, such as an in-vehicle communication field. However, good signal transmission has become possible.

  As such a visible light LED, an LED selected from an InGaN LED having an emission center near 520 nm, a PGaN LED having an emission center near 565 nm, and an AlGaInP LED having an emission center near 590 nm is used. However, it is not particularly limited.

  Hereinafter, the present invention will be described with reference to examples.

  Various evaluations performed on each example of the present invention were performed according to the evaluation methods described below. The configuration and evaluation results of the POF cable of each example are shown in each table together with comparative examples.

[Measurement of crystal melting heat (ΔH) and crystal melting point (Tm)]
The measurement was performed using a differential scanning calorimeter (DSC) (trade name: DSC-220, manufactured by Seiko Instruments Inc.). The sample was heated to 200 ° C. at a heating rate of 10 ° C./min, held for 5 minutes to melt, then cooled to 0 ° C. at 10 ° C./min, and again increased at a heating rate of 10 ° C./min. The temperature was maintained for 5 minutes, and the temperature was lowered at 10 ° C./minute, and the heat of crystal melting (ΔH) at this time was determined. The maximum point of the crystal melting peak was defined as the crystal melting point.

[Measurement of refractive index]
A 200 μm-thick film-shaped test piece was formed by a melt press, and the refractive index ( _n D ₂₃ ) of sodium D-line at room temperature of 23 ° C. was measured using an Abbe refractometer.

[Quantitative and qualitative analysis methods for low molecular weight compounds (monomer compounds and oligomeric compounds) in nylon resins]
50 g of nylon resin pellets and 100 ml of methanol were placed in a 300 ml eggplant flask and refluxed for 24 hours with stirring. After the reflux, the methanol was transferred to a beaker, and fresh methanol was added to the eggplant flask and refluxed for another 24 hours. After the reflux, a total of 200 ml of the extracted methanol solution was dried and the mass (Xg) of the obtained dried product was measured.

  This dried product was subjected to qualitative analysis using a mass spectrometer (MS) (manufactured by JEOL Ltd., trade name: SX-102), heat extraction GC-MS (manufactured by Agilent, trade name: HP5890 / 5972). It was.

  In addition, an appropriate amount of this dried product is dissolved again in methanol, and the dried product is separated by molecular weight by preparative size exclusion chromatography (SEC) (trade name: LC-10, manufactured by Nihon Analytical Industries, Ltd.). And collected. Furthermore, the qualitative analysis by nuclear magnetic resonance spectrum measurement (NMR) (The JEOL Co., Ltd. make, brand name: EX-270) was performed with respect to the extract.

  The content of low molecular weight compounds contained in the nylon resin pellets (total content of monomer compounds and oligomer compounds) was calculated by the following formula (iX).

    [Content] = X / 50 × 100 (mass%) (iX).

[Measurement of crystallinity (X)]
A density gradient tube made of n-heptane and carbon tetrachloride is prepared in a constant temperature water bath controlled at 25 ° C., and a sample is sampled and put into a size of about 5 mm × 5 mm, and read after 24 hours. The density ds was determined. Next, the crystallinity (X) was calculated according to the following general formula using this density ds.

Crystallinity (X) = (ds−da) / (dc−da)
(Where da: amorphous density, dc: crystalline density, ds: sample density)
The values of ds and dc were obtained from an X-ray diffraction method or an infrared spectrum. In the case of nylon 66, da = 1.09 and dc = 1.24 were used.

[Measurement of spherulite size]
Cut an ultrathin section from the functional coating layer of the POF cable with a microtome, observe the section with a polarizing microscope, take a photograph of the spherulite, measure the diameter of the spherulite with an image analyzer, and calculate the number average. This was calculated as the spherulite size.

[Measurement of full-wavelength transmission loss spectrum]
Using a light of excitation NA = 0.1, the transmission loss of the initial POF cable and the transmission loss of the POF cable after heat treatment at 105 ° C. for 5000 hours by the cut-back method of 25-1 m are measured at a wavelength of 400 nm. It measured in the range of -710nm.

[Heat resistance test method]
After leaving the POF cable or the POF strand in an oven at 105 ° C. for 5000 hours, the transmission loss is reduced by the cut-back method of 25-1 m using the light having the measurement wavelengths of 520 nm, 570 nm, 650 nm, and the excitation NA = 0.1. It was measured.

[Measurement of oxygen permeability]
In accordance with the method defined in ISO 14663-2: 1999 (Annex C), the oxygen transmission rate of the coating material was measured as follows.

A nylon resin composition for forming a functional coating layer is compression-molded by heating with a compression molding machine to produce a film-shaped test piece having a thickness of 100 μm, and an oxygen transmission rate manufactured by MOCON, USA Using a measuring apparatus (model name: OXTRAN (registered trademark)), the oxygen transmission rate [cm ³ · cm / (cm ² · sec · Pa)] was measured under the conditions of a temperature of 23 ° C. and a humidity of 0% RH.

[Reference Example 1]
A copolymer (refractive index of 1.50) having a core material of PMMA (refractive index 1.492) and a first cladding material of 3FM / 17FM / MMA / MAA (composition ratio 51/31/17/1 (mass%)). 416 to 1.417), VdF / TFE / HFP (composition ratio 43/48/9 (mass%), refractive index 1.375, crystal melting heat (ΔH) 14 mJ / mg) as the second cladding material. Each copolymer was used. These polymers are melted, supplied to a spinning head at 220 ° C., subjected to composite spinning using a concentric composite nozzle, and then stretched twice in the fiber axis direction in a hot air heating furnace at 140 ° C. A POF strand having a thickness of 10 μm and a diameter of 1 mm was obtained (abbreviated as “POF (A)” in Tables 1 and 2). The obtained POF strand had a good transmission loss of 130 dB / km at a wavelength of 650 nm.

  Cloth made of commercially available nylon 12 (manufactured by Daicel-Evonik Co., Ltd., trade name: Daiamide-L1640) in which 1% by mass of carbon black is added as a light-shielding coating layer on the outer periphery of the produced POF strand, and set at 210 ° C. A POF primary cable having an outer diameter of 1.50 mm having a light shielding coating layer (thickness: 250 μm) was obtained by coating with a crosshead cable coating apparatus using a head die.

  The obtained POF primary cable had a good initial transmission loss of 134 dB / km at a wavelength of 650 nm. However, the transmission loss after the heat test was 560 dB / km, and a decrease in the optical transmission performance was observed. Also, the transmission loss at a wavelength of 520 nm and a wavelength of 570 nm after the heat resistance test was 1000 dB / km or more and 980 dB / km, respectively, which was remarkably increased with respect to the initial transmission loss.

  The total content of monomers and oligomers contained in nylon 12 of the light shielding coating layer was 1.18% by mass. A qualitative analysis was conducted on a sample obtained from the methanol solution after extraction. As a result, the extract was obtained from monomer monomers (12-aminododecanoic acid and ω-laurolactam) which are raw materials of nylon 12, and two monomers. It was a multimer (amino aliphatic carboxylic acid compound and cyclic lactam compound).

[Reference Example 2]
On the outer periphery of the POF strand (POF (A)) prepared in Reference Example 1, as a protective coating layer, boribylene terephthalate (PBT) resin (Toray DuPont, trade name: Hytrel 4047), light shielding coating As a layer, a protective coating layer (thickness of 40 μm) was prepared in the same manner as in Reference Example 1 except that a commercially available nylon 12 (manufactured by Daicel Degussa, trade name: Daiamide-L1640) to which 1% by mass of carbon black was added was provided. And a POF primary cable having an outer diameter of 1.51 mm having a light shielding coating layer (thickness: 215 μm).

  The molecular weight of the polytetramethylene glycol unit constituting the soft segment part (B) of the PBT resin is 430, the total number of moles of polybutylene terephthalate units (a) contained in the hard segment part (A), and The ratio (a / b) of the total number of moles (b) of the polybutylene terephthalate units contained in the soft segment part (B) is 25/75, the Shore D hardness is 47, the melting point is 199 ° C., and the melt flow index is 22 g / 10. Minutes.

  The obtained POF primary cable had a good initial transmission loss of 134 dB / km at a wavelength of 650 nm. Furthermore, the transmission loss after the heat test was as good as 185 nm. Moreover, the transmission loss of wavelength 520nm and wavelength 570nm after a heat test was 1000 dB / km or more and 460 dB / km, respectively.

  The transmission loss spectrum when the obtained POF primary cable is left at 105 ° C. for 5000 hours is shown in FIG. 4 in comparison with the initial case. It can be seen that the transmission loss on the short wavelength side is remarkably increased.

[Reference Example 3]
On the outer periphery of the POF primary cable having an outer diameter of 1.51 mm produced in Reference Example 2, a cross head die set with nylon 66 (product name: UBE nylon 2015B, manufactured by Ube Industries, Ltd.) as a functional coating layer at 275 ° C. The POF secondary cable having an outer diameter of 2.31 mm having a functional coating layer (thickness: 400 μm) was obtained by covering with the crosshead cable coating apparatus used.

  The obtained POF secondary cable had a good initial transmission loss of 136 dB / km at a wavelength of 650 nm, and a good transmission loss of 205 dB / km after the heat resistance test. Moreover, the transmission loss of wavelength 520nm and wavelength 570nm after a heat test was 1000 dB / km or more and 662 dB / km, respectively.

  The transmission loss spectrum when the obtained POF secondary cable is left at 105 ° C. for 5000 hours is shown in FIG. 5 in comparison with the initial case.

[Reference Example 4]
Reference Example, except that nylon 66 resin composition containing 98% by mass of nylon 66 (product name: UBE nylon 2015B) and 2.0% by mass of ultramarine is used as the functional coating layer. A POF secondary cable was obtained in the same manner as in No. 3.

  The obtained POF secondary cable had good initial transmission loss of 136 dB / km at a wavelength of 650 nm and 197 dB / km after the heat resistance test. Moreover, the transmission loss of wavelength 520nm and wavelength 570nm after a heat test was 1000 dB / km or more and 506 dB / km, respectively.

[Example 1]
As a functional coating layer, nylon 66 (manufactured by Ube Industries, trade name: UBE nylon 2015B) is 85% by mass, brominated polystyrene (trade name: HP-3010, trade name: HP-3010, polystyrene-converted molecular weight 50,000 measured by GPC). A nylon 66 resin composition containing 10% by mass of bromine atom content of 68.5% by mass and antimony pentoxide (manufactured by Nissan Chemical Co., Ltd., trade name: Sun Epoch) at a ratio of 5% by mass was used. Except for the above, a POF secondary cable was obtained in the same manner as in Reference Example 3. In addition, content of the bromine atom in this functional coating layer is equivalent to 6.85 mass%.

  The obtained POF secondary cable had good initial transmission loss at a wavelength of 650 nm of 134 dB / km and a transmission loss after a heat resistance test of 187 dB / km. Moreover, the transmission loss of wavelength 520nm and wavelength 570nm after a heat test was 1000 dB / km or more and 351 dB / km, respectively.

[Example 2]
As the functional coating layer, 83% by mass of nylon 66 (manufactured by Ube Industries, trade name: UBE nylon 2015B), 10% by mass of brominated polystyrene (trade name: HP-3010, manufactured by Albemarle), antimony pentoxide (Nissan) POF secondary cable in the same manner as in Reference Example 3 except that a nylon 66 resin composition containing 5% by mass of Chemical Company, trade name: Sun Epoch) and 2.0% by mass of ultramarine was used. Got.

  The obtained POF secondary cable had a very good initial transmission loss at a wavelength of 650 nm of 134 dB / km and a transmission loss after a heat resistance test of 140 dB / km. Furthermore, the transmission loss at a wavelength of 520 nm and a wavelength of 570 nm after the heat test was 165 dB / km and 104 dB / km, respectively, which were very good.

  The transmission loss spectrum when the obtained POF secondary cable is left at 105 ° C. for 5000 hours is shown in FIG. 6 in comparison with the initial case. It can be seen that the increase in transmission loss on the short wavelength side is significantly suppressed as compared with FIG. 4 (Reference Example 2, POF primary cable) and FIG. 5 (Reference Example 3).

[Example 3]
On the outer periphery of the POF primary cable having an outer diameter of 1.51 mm prepared in Reference Example 1, 83% by mass of nylon 66 (manufactured by Ube Industries, trade name: UBE nylon 2015B) as a functional coating layer, brominated polystyrene (Albemarle) Product name: HP-3010, polystyrene conversion molecular weight 50,000 measured by GPC, bromine atom content 68.5% by mass) 10% by mass, antimony pentoxide (manufactured by Nissan Chemical Co., Ltd., product name: Sun) A nylon 66 resin composition containing 5% by mass of epoch and 2.0% by mass of ultramarine is coated with a crosshead cable coating apparatus using a crosshead die set at 275 ° C., and a functional coating layer ( A POF secondary cable having an outer diameter of 2.31 mm having a thickness of 400 μm was obtained.

  The obtained POF secondary cable had a good initial transmission loss at a wavelength of 650 nm of 136 dB / km and a good transmission loss of 164 dB / km after the heat resistance test. Moreover, the transmission loss of wavelength 520nm and wavelength 570nm after a heat test was 899 dB / km or more and 292 dB / km, respectively.

[Example 4]
A POF secondary cable was obtained in the same manner as in Example 3 except that the nylon 66 resin composition described in Table 2 was used as the functional coating layer. The evaluation results of the obtained POF secondary cable are shown in Table 3.

[Examples 5 to 8]
A POF secondary cable was obtained in the same manner as in Reference Example 3 except that the material described in Table 2 was used as the protective coating layer and the nylon 66 resin composition described in Table 2 was used as the functional coating layer. The evaluation results of the obtained POF secondary cable are shown in Table 3.

[Examples 9, 10 and Comparative Example 1]
Except for the use of the materials described in Table 1 for the first and second claddings of POF strands (Example 9 is POF (B), Example 10 is POF (C), and Comparative Example 1 is POF (D)). Produced a POF strand having a thickness of 10 μm and a diameter of 1 mm in the same manner as in Reference Example 2.

  Next, a POF secondary cable was obtained in the same manner as in Reference Example 3 except that the materials described in Table 2 were used as the protective coating layer and the functional coating layer on the outer periphery of these POF wires. The evaluation results of the obtained POF secondary cable are shown in Table 3.

[Example 11]
As a light shielding coating layer, a functional nylon coating (manufactured by Arkema, trade name: Rilsan BMF-0, total content of monomer and oligomer is 0.95% by mass) to which 1% by mass of carbon black is added is used as a light shielding coating layer. A POF secondary cable was obtained in the same manner as in Reference Example 3 except that the nylon 66 resin composition described in Table 2 was used as the layer. The evaluation results of the obtained POF secondary cable are shown in Table 3.

[Comparative Example 2]
Other than using commercially available nylon 12 (manufactured by EMS / CHEMIE AG, trade name: Grilamide L16A, total content of monomer and oligomer is 1.69% by mass) to which 1% by mass of carbon black is added as the light shielding coating layer Obtained a POF secondary cable in the same manner as in Example 2. The evaluation results of the obtained POF secondary cable are shown in Table 3.

[Comparative Examples 3 to 4]
Reference Example, except that the nylon 66 resin composition described in Table 2 using a phthalocyanine compound (Comparative Example 3) and an anthraquinone compound (Comparative Example 4), which are organic pigments, was used as a functional coating layer. A POF secondary cable was produced by the same method as in FIG. The evaluation results of the obtained POF secondary cable are shown in Table 3.

[Comparative Examples 5-6]
As a functional coating layer on the outer periphery of the POF primary cable produced in Reference Example 2, commercially available nylon 12 (manufactured by Daicel-Evonik Co., Ltd., trade name: Daiamide-L1640) is used as a functional coating layer, and in Comparative Example 6, this nylon 12 is used. The resin composition described in Table 2 as a main component is coated with a crosshead cable coating apparatus using a crosshead die set at 220 ° C., and a POF having an outer diameter of 2.31 mm having a functional coating layer (thickness 400 μm). A secondary cable was produced. The evaluation results of the obtained POF secondary cable are shown in Table 3.

[Comparative Examples 7-8]
In Comparative Example 7, the POF primary cable produced in Reference Example 1 was used, and in Comparative Example 8, the POF cable produced in Reference Example 2 was used. On the outer periphery of these POF primary cables, a commercially available nylon 612 ( Daicel-Evonik Co., Ltd., trade name: Daiamide-N1901) is coated with a crosshead cable coating apparatus using a crosshead die set at 210 ° C., and has an outer diameter of 2.31 mm having a functional coating layer (thickness 400 μm). A POF secondary cable was produced. The evaluation results of the obtained POF secondary cable are shown in Table 3.

[Example 12]
A PGaN-based LED having a light emission center near 565 nm is attached to the end of the POF secondary cable manufactured in Example 2 and used as a signal transmission cable, and left in an environment of 105 ° C. for 5000 hours even in the initial stage. Later, it was confirmed that signals could be sent stably.

[Example 13]
An InGaN-based LED having a light emission center near 520 nm is attached to the end of the POF secondary cable manufactured in Example 2 and used as a signal transmission cable, and left in an environment of 105 ° C. for 5000 hours at an initial stage. Later, it was confirmed that signals could be sent stably.

[Example 14]
An AlGaInP LED having a light emission center near 590 nm is attached to the end of the POF secondary cable manufactured in Example 2 and used as a signal transmission cable, and left at a temperature of 105 ° C. for 5000 hours even in the initial stage. Later, it was confirmed that signals could be sent stably.

[Example 15]
A PGaN-based LED having a light emission center near 565 nm is attached to the end of the POF secondary cable manufactured in Example 7 and used as a signal transmission cable, and is left in an environment of 105 ° C. for 5000 hours at an initial stage. Later, it was confirmed that signals could be sent stably.

[Example 16]
An AlGaInP LED having a light emission center near 590 nm was attached to the end of the POF secondary cable produced in Example 8 and used as a signal transmission cable. The device was left in an environment of 105 ° C. for 5000 hours even in the initial stage. Later, it was confirmed that signals could be sent stably.

[Example 17]
An InGaN-based LED having a light emission center near 520 nm was attached to the end of the POF secondary cable manufactured in Example 11 and used as a signal transmission cable, which was left in an environment of 105 ° C. for 5000 hours even in the initial stage. Later, it was confirmed that signals could be sent stably.

[Comparative Example 9]
A PGaN-based LED having a light emission center near 565 nm was attached to the end of the POF secondary cable produced in Comparative Example 3 and used as a signal transmission cable. Although the signal could be sent stably at the initial stage, the signal could not be sent stably after being left in a 105 ° C. environment for 5000 hours.

[Comparative Example 10]
A PGaN-based LED having a light emission center near 565 nm was attached to the end of the POF secondary cable produced in Comparative Example 6 and used as a signal transmission cable. Although the signal could be sent stably at the initial stage, the signal could not be sent stably after being left in a 105 ° C. environment for 5000 hours.

  The abbreviations in the table indicate the following compounds.

VdF: vinylidene fluoride,
TFE: tetrafluoroethylene,
HFP: hexafluoropropylene,
PFPVE: perfluoropentafluoropropyl vinyl ether (CF ₂ = CFOCH ₂ CF ₂ CF ₃ ),
MMA: methyl methacrylate,
MAA: methacrylic acid,
3FM: 2,2,2-trifluoroethyl methacrylate,
17FM: 2- (perfluorooctyl) ethyl methacrylate,
PBT resin: polybutylene terephthalate resin (Toray DuPont, trade name: Hytrel 4047),
PSt-based resin: polystyrene resin (manufactured by Nippon Polystyrene Co., Ltd., trade name: Nippon Polystyrene G120K),
Acrylic resin: MMA and butyl acrylate (BA) copolymer (composition ratio 80/20, manufactured by Mitsubishi Rayon Co., Ltd.)
PVdF: polyvinylidene fluoride resin (Arkema, trade name: KYNAR710),
EVAL resin: ethylene-vinyl alcohol copolymer (composition ratio 32/68 mol%, manufactured by Kuraray Co., Ltd., trade name: EVAL F104),
PA12: nylon 12 (manufactured by Daicel-Evonik, trade name: Daiamide-L1640),
PA12 (B): nylon 12 (manufactured by EMS / CHEMIE, trade name: Grilamide L16A),
PA11: nylon 11 (made by Arkema, trade name: Rilsan BMF-0),
PA66: nylon 66 (made by Ube Industries, trade name: UBE nylon 2015B),
PA612: nylon 612 (manufactured by Daicel-Evonik, trade name: Daiamid-N1901),
BrPSt: Brominated polystyrene (manufactured by Albemarle, trade name: HP-3010),
AnOx: antimony pentoxide (manufactured by Nissan Chemical Co., Ltd., trade name: Sun Epoch),
Phthalocyanine compound (colorant): (Ciba Specialty Chemicals, trade name: IRGALITE Blue-GBP),
Anthraquinone compound (colorant): (Bayer, trade name: Pigment Yellow 193).

101 Plastic optical fiber (POF)
DESCRIPTION OF SYMBOLS 102 Light shielding coating layer 103 Functional coating layer 104 Protective coating layer 201 Dice 201a Tip surface 202 Nipple 203 Flow path of coating material 204 Axis line of path through which POF strand 1 passes 205 Flow path of coating material at die-nipple portion

Claims (8)

A plastic optical fiber cable having a core and a clad layer composed of one or more layers formed on the outer periphery of the core, and a plastic optical fiber cable having a coating layer on the outer periphery thereof,
The core is made of polymethyl methacrylate or a copolymer mainly composed of methyl methacrylate,
The clad layer has at least an outermost layer comprising a fluoroolefin-based resin containing a tetrafluoroethylene unit and having a heat of crystal melting in differential scanning calorimetry (DSC) of 40 mJ / mg or less,
The coating layer is composed of a light shielding coating layer and a functional coating layer in order from the inside,
The functional coating layer contains a bromine-based polymer flame retardant, has a crystal melting point by differential scanning calorimetry (DSC) in the range of 240 ° C. or higher and 280 ° C. or lower, and is defined in ISO 14663-2: 1999 (Annex C). The oxygen permeability P (cm ³ · cm / (cm ² · sec · Pa)) at the temperature T (K) measured by the above method is expressed by the following general formula (1)
P <8 × 10 ⁻² × exp (−5600 / T) (1)
Satisfying, formed from a non-colored or pigmented nylon resin composition with an inorganic pigment,
The light shielding coating layer contains at least one nylon resin of nylon 11 and nylon 12 as a main component, and the total content of monomer compounds and oligomer compounds derived from the nylon resin contained is 1.5% by mass or less. A plastic optical fiber cable formed from a resin composition in the range of   2. The plastic optical fiber cable according to claim 1, wherein the functional coating layer is formed of a nylon resin composition having a crystallinity of 30% to 55%.   3. The plastic optical fiber cable according to claim 1, wherein the functional coating layer is formed of a nylon resin composition having an average diameter of spherulite size by microscopic observation in a range of 0.01 μm to 40 μm.   The plastic optical fiber cable according to any one of claims 1 to 3, wherein the functional coating layer is formed of a nylon resin composition containing nylon 66 as a main component.   The functional coating layer contains bromine-substituted polystyrene or poly (brominated benzyl acrylate) as the brominated polymer flame retardant so that the content of bromine atoms is in the range of 1.5 mass% to 30 mass%. Furthermore, the plastic optical fiber cable according to any one of claims 1 to 4, wherein the plastic optical fiber cable is formed from a nylon resin composition containing 0 to 20% by mass of antimony oxide.   The plastic optical fiber cable according to any one of claims 1 to 5, wherein the functional coating layer is formed of a nylon resin composition containing an inorganic pigment in a range of 0.1 mass% to 10 mass%. .   Contains polybutylene terephthalate resin, (meth) methyl acrylate resin, styrene resin, vinylidene fluoride homopolymer, ethylene unit and vinyl alcohol unit between the plastic optical fiber and the light shielding coating layer The plastic optical fiber cable according to any one of claims 1 to 6, further comprising a protective coating layer made of a resin selected from copolymers to be made.   8. A signal transmission method comprising transmitting a signal by combining the plastic optical fiber cable according to claim 1 with a visible light emitting diode having a light emission center in a wavelength range of 500 nm to 600 nm.

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