JP2009175683A - Plastic optical fiber and plastic optical fiber cord - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic optical fiber and a plastic optical fiber cord that are well-balanced and superior in properties such as light transmission, heat resistance, moist-heat resistance, bend resistance, and adhesiveness with a coating layer. <P>SOLUTION: In a plastic optical fiber having a core/clad 2-layered structure, the copolymer forming the clad layer contains the following components, and the melt flow rate (MFR) of the copolymer is 5-24 g/10 min., as the characteristic of the plastic optical fiber. (Components): 52-72 mol% vinylidene fluoride, 26-46 mol% tetra fluoro ethylene, and 2-8 mol% hexa fluoro propylene. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention has a good balance of heat resistance, moist heat resistance, bending resistance, adhesion to a coating layer, and the like, and is a plastic optical fiber used for indoor wiring, automobile wiring, and the like, and a plastic optical fiber using the same It is about the code.

  Plastic optical fibers (hereinafter abbreviated as POF) are superior to glass-based optical fibers in terms of processability, handleability, and manufacturing costs, so they can be used for short-distance optical communication transmission, photoelectric sensors, light guides, etc. in use. In particular, recently, a plastic optical fiber cord (hereinafter abbreviated as POF cord) in which a wiring for information communication in an automobile is coated with a thermoplastic resin such as nylon (polyamide) has been proposed.

  The POF is composed of two types of polymers, a core and a clad. For the core, a polymer having excellent transparency and good weather resistance is generally used, as represented by polymethyl methacrylate (hereinafter abbreviated as PMMA). On the other hand, the clad needs to have a lower refractive index than the core in order to confine light inside the core, and fluorine-containing polymers are widely used.

  For indoor wiring and information communication wiring in automobiles, POF is often constructed in a narrow space bent in a hot and humid environment, and requires heat resistance, heat and humidity resistance, bending resistance, bending loss resistance, etc. Is done.

  Furthermore, the POF cord is usually used with a connector attached to the end, but when peeling off the coating layer, it is easy to damage the POF bare wire. A mounting method is performed. When the covering layer is connected and fixed to the connector component, it is necessary that the contact strength between the bare POF wire and the covering layer be high in order to maintain the connection strength between the connector and the POF cord.

  Therefore, it has been studied to polymer blend or copolymerize a clad material with the resin of the coating layer, or to use a special highly adhesive resin.

  By the way, for the purpose of improving the heat resistance, heat-and-moisture resistance, bending resistance, bending loss resistance characteristics, etc. of POF, the cladding is made of vinylidene fluoride (vinylidene fluoride), tetrafluoroethylene, and hexafluoropropylene having a low refractive index. Several techniques have been proposed for improving bending properties using terpolymers.

  For example, as shown in Patent Document 1, as a cladding material, a ternary copolymer having a vinylidene fluoride component of 30 to 50% by weight, a tetrafluoroethylene component of 25 to 55% by weight, and a hexafluoropropylene component of 15 to 25% by weight is used. A POF using a polymer is disclosed.

  Patent Document 2 discloses that the sheath (cladding) material is in the range of 45 to 57 mol% of vinylidene fluoride component, 31 to 35 mol% of tetrafluoroethylene component, and 12 to 20 mol% of hexafluoropropene component. A POF in which a protective layer made of a vinylidene fluoride resin is coated on the outside of a bare POF wire using a terpolymer is disclosed.

  In Patent Document 3, the first cladding is made of a resin having a higher refractive index than that of the second cladding, and the second cladding is composed of 30 to 92 mol% of vinylidene fluoride component, 0 to 55 mol% of tetrafluoroethylene component, hexa A POF comprising a terpolymer in the range of 8-25 mol% of the fluoropropene component is disclosed. Further, (meth) acrylic acid long chain fluoroalkyl ester / (meth) acrylic acid short chain fluoroalkyl ester / (meth) acrylic acid methyl copolymer is exemplified as an optimum material for the first cladding.

  In Patent Document 4, the first clad is a copolymer containing short-chain perfluoroalkyl methacrylate and methyl methacrylate, the second clad is a hexafluoropropylene component of 10 to 25% by weight, and a tetrafluoroethylene component of 35 to 70% by weight. %, A POF comprising a copolymer containing 15 to 45% by weight of a vinylidene fluoride component is disclosed.

In Patent Document 5, the first clad is a copolymer containing a long chain fluoroalkyl methacrylate / short chain fluoroalkyl methacrylate / other copolymerizable monomers, and the second clad is a vinylidene fluoride component. A POF comprising a terpolymer in the range of 01 to 92 mol%, tetrafluoroethylene component 0.01 to 55 mol%, hexafluoropropylene component 4.0 to 7.99 mol% is disclosed.
Japanese Patent No. 2857411 (Claims) Japanese Patent No. 3850961 (Claims) JP 11-101915 A (page 3) JP 2002-156533 A (Claims) JP 2003-139773 A (Claims)

  The POF disclosed in Patent Document 1 has a high numerical aperture and excellent translucency, but there are problems such as the clad material being flexible and sticking at the time of winding, inferior in heat resistance and moist heat resistance, and difficult to put into practical use. Met.

  In addition, the POF disclosed in Patent Document 2 has a problem that heat resistance, moist heat resistance, adhesion to a coating layer, etc. are inferior although the above-mentioned adhesiveness is improved by adopting a two-layer clad structure. It was.

  Further, the second clad in the POF disclosed in Patent Documents 3, 4, and 5 has improved heat resistance and moist heat resistance, but has insufficient adhesion to the coating layer.

  An object of the present invention is a plastic optical fiber used for indoor wiring, automobile wiring, etc., with excellent balance of light leakage resistance, heat resistance, heat and humidity resistance, bending resistance, adhesion to a coating layer, etc. It is to provide a plastic optical fiber cord using the same.

That is, the first invention of the present invention is
(1) Core / cladding two-layer structure having a core made of a polymer mainly composed of methyl methacrylate and a clad layer made of an organic polymer having a refractive index smaller than the refractive index of the core on the outer periphery of the core In the plastic optical fiber, the copolymer forming the clad layer contains the following components, and the melt flow rate (MFR) value of the copolymer is 5 to 24 g / 10 min. Plastic optical fiber.
Vinylidene fluoride: 52-72 mol%
Tetrafluoroethylene: 26-46 mol%
Hexafluoropropylene: 2-8 mol%
It is.

The second invention of the present invention is:
(2) Core / first clad / second clad having a core made of a polymer mainly composed of methyl methacrylate and a clad layer in which the first clad and the second clad are laminated in this order on the outer periphery of the core. In a plastic optical fiber having a three-layer structure, a cladding layer is laminated on the outer periphery of a core in the order of a first cladding and a second cladding, and the first cladding is expressed by the formula (1)
_{CH 2 = C (CH 3)} -COOCH 2 (CF 2) n R (1)
(However, R represents a fluorine atom or a hydrogen atom, and n represents an integer of 1 to 4.)
And a copolymer containing 40 to 90 mol% perfluoroalkyl methacrylate and 10 to 60 mol% methyl methacrylate as a copolymerization component, and the second clad contains the following components, and A plastic optical fiber comprising a copolymer having a melt flow rate (MFR) value of 5 to 24 g / 10 min.
Vinylidene fluoride: 52-72 mol%
Tetrafluoroethylene: 26-46 mol%
Hexafluoropropylene: 2-8 mol%
It is.

Furthermore, the present invention is preferably as follows.
(3) A plastic optical fiber cord, further comprising one or more coating layers on the outer periphery of the plastic optical fiber according to (1) or (2), wherein the coating layer is made of a thermoplastic resin.
(4) The plastic optical fiber cord according to (3) above, wherein the thermoplastic resin is a resin mainly composed of nylon 12 or polypropylene.
(5) The plastic optical fiber cord according to the above (3) or (4), wherein the adhesive force between the plastic optical fiber and the coating layer in contact with the outer periphery thereof is 50 N or more.

  According to the present invention, a plastic optical fiber and a plastic that are excellent in light transmission, heat resistance, moist heat resistance, bending resistance, adhesion with a coating layer, and the like, and are used for indoor wiring, automobile wiring, and the like. An optical fiber cord can be provided.

  The polymer mainly composed of methyl methacrylate (hereinafter abbreviated as MMA) forming the core of POF in the present invention includes polymethyl methacrylate (PMMA) or a copolymer having MMA of 70% by weight or more, For example, (meth) acrylic acid ester, (meth) acrylic acid, (substituted) styrene, (N-substituted) maleimide, etc. are copolymerized, or modified heavy polymers such as glutaric anhydride and glutarimide are polymerized. Examples include coalescence. Examples of (meth) acrylic acid esters include methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, phenyl methacrylate, bornyl methacrylate, adamantyl methacrylate, and the like as substituted styrene. Examples of N-substituted maleimide include N-isopropylmaleimide, N-cyclohexylmaleimide, N-methylmaleimide, N-ethylmaleimide, and N-o-methylphenylmaleimide. A plurality of these copolymer components may be used, and a small amount of other components may be used. Further, a stabilizer such as an antioxidant may be contained in an amount that does not adversely affect the light transmission property. Among these polymers, PMMA is most preferable from the viewpoints of productivity, translucency, environmental resistance and the like.

The clad in the first invention comprises an organic polymer having a refractive index smaller than that of the core, the copolymer contains the following components, and the melt flow rate (MFR) value of the copolymer: Is 5 to 24 g / 10 min.
Vinylidene fluoride: 52-72 mol%
Tetrafluoroethylene: 26-46 mol%
Hexafluoropropylene: 2-8 mol%

  When the copolymerization component is out of this range, low refractive index, low crystallization (low translucency) cannot be achieved, or the core has poor adhesion to the MMA-based (co) polymer, Mechanical properties such as bending resistance are greatly reduced, low crystallization (colorless and transparent) cannot be achieved, mechanical properties such as bending resistance are greatly reduced, and there is stickiness, heat resistance It has problems such as insufficient properties.

  Also, the melt flow rate (hereinafter abbreviated as MFR) value of the above copolymer is in the range of 5 to 24 g / 10 min (conditions: 230 ° C., load 2.16 kg, orifice diameter 2 mm, length 8 mm). It is necessary to be. The range of the melt flow rate of the preferable copolymer is 5 to 22 g / 10 min, and particularly preferably 6 to 22 g / 10 min. When the MFR value is less than 5, the melt viscosity is too high and molding becomes difficult, and the translucency deteriorates. If it exceeds 24, the molecular weight is low and the mechanical properties and heat resistance are poor.

In the second invention, a POF having a two-layer clad structure in which the copolymer is the second clad can be used. In this case, the formula (1) is used as the first cladding.
_{CH 2 = C (CH 3)} -COOCH 2 (CF 2) n R (1)
(However, R represents a fluorine atom or a hydrogen atom, and n represents an integer of 1 to 4.)
From the viewpoint of transparency and heat resistance, it is necessary to use a copolymer containing 40 to 90 mol% perfluoroalkyl methacrylate and 10 to 60 mol% methyl methacrylate as a copolymerization component. . Perfluoroalkyl methacrylates other than those represented by the above formula (1) have a copolymer that becomes cloudy, yellowed, or has extremely poor mechanical properties. When POF is used, translucency, heat resistance, flex resistance, etc. May be insufficient.

  The perfluoroalkyl methacrylate used in the present invention further includes (meth) acrylic acid esters other than MMA, methacrylic acid having an alicyclic hydrocarbon in the ester, (meth) acrylic acid, (substituted) styrene, (N -Substitution) Maleimide or the like may be copolymerized within about 10% by weight.

  Also, the refractive index of the first cladding is usually made of a resin that is lower than that of the core and higher than that of the second cladding. If the second clad has a lower refractive index than the first clad, it is preferable because the POF is bent or functions to reflect and collect the light leaking from the irregular portion of the first clad.

The theoretical numerical aperture of the POF using the first cladding is preferably NA = 0.45 to 0.52. The theoretical numerical aperture NA as: = ((the refractive index of the ^{core) 2} - (refractive index of the first ^{cladding) 2) 1/2}
It is represented by the refractive index difference between the core and the first cladding.

  By setting the numerical aperture to 0.45 to 0.52, it is possible to use the clad having a well-balanced physical property conventionally used in one layer as the first clad of the present invention.

  Hereinafter, the first invention and the second invention will be described together.

  The POF of the present invention can be produced by a conventional method. For example, a composite spinning method in which a core / clad two-layer core-sheath structure or a core / first clad / second clad three-layer core-sheath structure is formed by discharging from a concentric composite composite die is preferably used.

  In the case of a core / cladding two-layer core-sheath structure, the thickness of the cladding layer is preferably 2 to 20 μm, particularly preferably 5 to 15 μm. In the case of a three-layer core-sheath structure of core / first clad / second clad, the thickness of the first and second clads is preferably 2 to 10 μm. Furthermore, it is preferable to make it thin so as not to cause a problem in characteristics, and it is particularly preferable that the total thickness of the first and second claddings is 5 to 15 μm.

  Subsequently, for the purpose of improving mechanical properties, a stretching process of about 1.2 to 3 times is generally performed to form POF. The outer diameter of this POF is usually about 0.1 to 3 mm, and may be appropriately selected according to the purpose, but is preferably 0.5 to 1.5 mm from the viewpoint of handleability.

  The POF of the present invention is preferably a cord having one or more coating layers on the outer periphery thereof. The coating layer is preferably made of a thermoplastic resin. For example, polyethylene, polypropylene or copolymers thereof, blends, olefin polymers containing an organosilane group, ethylene-vinyl acetate copolymer, polyvinyl chloride, Polyamide resins such as vinylidene fluoride and nylon 12, polyester resins, nylon elastomers, polyester elastomers, urethane resins, and fluorine resins are preferably used.

  In particular, when a resin mainly composed of nylon 12 or polypropylene is used for the coating layer in contact with the outer periphery of the POF, it is excellent in oil resistance, wear resistance, heat resistance, impact resistance, etc. preferable.

  In the present invention, the resin mainly composed of nylon 12 refers to a nylon 12 homopolymer or a copolymer or polymer blend containing 50% by weight or more of nylon 12, and includes a plasticizer, a flame retardant, and an antioxidant. It may contain a stabilizer such as an agent, an anti-aging agent, a UV stabilizer, or carbon black for coloring, a pigment, a dye, etc., and has a flexural modulus of 1.0 to 2.0 GPa and a tensile yield point strength. General commercial products with characteristics such as 30 to 55 MPa and deflection temperature under load (0.45 MPa) of 135 to 150 ° C. can be used, but characteristics in other ranges by inclusion of the above additives and polymer blends with other resins. It doesn't matter.

  In the present invention, the polypropylene-based resin refers to polypropylene, a copolymer including a cross-link with polyethylene, or a mixture thereof, in addition to a flame retardant, an antioxidant, and an anti-aging agent. May include a stabilizer, a stabilizer such as a UV stabilizer, or a pigment for coloring, and has a tensile yield strength of 20 to 35 MPa (ASTM D638), a flexural modulus of 1.1 to 1.7 GPa (ASTM D790), General commercial products having characteristics such as Rockwell hardness (R) 80 to 110 (JIS-K7202) and deflection temperature under load of 105 to 130 ° C. (JIS-K7207, 0.45 MPa) can be used. It may have a characteristic in a range other than this by a polymer blend with the above resin.

  In this invention, it is preferable that the adhesive force with the coating layer which touches the outer periphery of a plastic optical fiber is 50 N or more. If the adhesion force is less than 50 N, the POF bare wire and the coating layer may be peeled off when the POF cord is pulled out from the connector, and the POF end face may be retracted to reduce the reliability of optical coupling. Further, there is a concern that pistoning may occur even in environmental changes, and the minimum value is preferably 50 N or more. Further preferable adhesion is 60 N or more.

  In the POF cord of the present invention, a second coating layer may be further covered on the outer periphery of the coating layer. The second coating layer is preferably softer than the (first) coating layer, and is a block containing a nylon 12 plasticizer-containing material, a copolymer with other nylons such as nylon 6, polyether, polyester, etc. Nylon elastomer which is a copolymer can be used preferably, and other elastomers such as polyester elastomer, polyolefin elastomer, polyurethane elastomer, polystyrene elastomer, polyvinyl chloride, acrylate or vinyl acetate and ethylene copolymer. In addition to flame retardants, it may contain antioxidants, anti-aging agents, stabilizers such as UV stabilizers, carbon black for coloring, pigments, dyes, etc. A tension member such as Kevlar may be inserted between them. The coating layer can be formed by a conventional method such as a melt extrusion method using a cross header die.

  Hereinafter, the present invention will be described in more detail with reference to examples. Evaluation was performed by the following method.

  Translucency: Measured by a 30 / 2m cut-back method using halogen parallel light (wavelength 650 nm, incident NA = 0.25).

Heat resistance: Put a plastic optical fiber cord with a test length of 28m in a high-temperature oven (PHH-200 manufactured by Tabai Espec Co., Ltd.). The amount of change was used as an index. (The average value of n = 3. Negative value indicates a decrease in light amount)
Moist heat resistance: Evaluation was similarly performed at a temperature of 85 ° C. and a humidity of 85%.

  Bending loss: Using a 660 nm LED, the amount of light when 360 ° was wound around a metal rod having a radius of 10 mm was measured, and the amount of decrease before and after that was used as an index (average value of n = 3).

  Adhesion force: 60 mm of coating layer is peeled from 90 mm of the primary coating cord, the fiber is exposed, the fiber is passed through a metal plate with a hole of fiber diameter +0.1 mm, and the tensile speed is measured with a commercially available tensile tester. The fiber was pulled out at 50 mm / min, and the lowest yield strength at n = 20 was shown as the adhesion.

  Refractive index: An Abbe refractometer was used as a measuring device, and the measurement was performed in an atmosphere at room temperature of 25 ° C.

  Number of continuous bends: A 500 g load is applied to one end of the primary coated cord, supported by a mandrel with a diameter of 30 mmφ, and the other end of the fiber is bent continuously at an angle of 90 ° around the support point, and the cord is cut The number of times until the measurement was measured (average value of n = 5).

  Melt flow rate (MFR): According to Japanese Industrial Standard JIS K7210, the amount discharged from the nozzle for 10 minutes was measured under the conditions of 230 ° C., load 2.16 kg, nozzle diameter 2 mm, and length 8 mm.

[Example 1]
As a clad material, a vinylidene fluoride (2F) / tetrafluoroethylene (4F) / hexafluoropropylene (6F) copolymer (refractive index: 1.371 MFR12) having the composition shown in Table 1 was supplied to a composite spinning machine. Further, PMMA ((refractive index: 1.492)) produced by continuous soul polymerization is supplied as a core material to a composite spinning machine, and the core and cladding are melt-spun at 235 ° C., and the fiber diameter is 1000 μm (core A POF having a diameter of 980 μm and a cladding thickness of 10.0 μm was obtained.

  Furthermore, 0.25% by weight of carbon black is added to nylon 12 resin (manufactured by Daicel Huls; Daiamide L1640) having a tensile yield point strength of 41 MPa, a flexural modulus of 1.3 GPa, and a deflection temperature under load of 145 ° C. A POF cord having an outer diameter of 1.5 mm was formed by coating at 0 ° C.

  The POF code thus obtained was evaluated by the above evaluation method, and the results are shown in Table 2. As can be seen from Table 2, the adhesion, translucency, repeated flexibility, heat resistance, moist heat resistance, and bending loss were all excellent.

[Examples 2 to 6]
A POF cord was obtained in the same manner as in Example 1 except that the first cladding was changed as shown in Table 1 (however, all the fiber diameters were unified to 1000 μm). These POF codes were used for the same evaluation as in Example 1, and the results are shown in Table 2.

  In Examples 2 to 6 of the present invention, the adhesion between the fiber and the first coating layer was high, and all of the translucency, bending resistance, heat resistance, moist heat resistance, and bending resistance were excellent.

[Comparative Examples 1-4]
A POF cord was obtained in the same manner as in Example 1 except that the first cladding was changed as shown in Table 1 (however, all the fiber diameters were unified to 1000 μm). These POF codes were used for the same evaluation as in the examples, and the results are shown in Table 2.

  In Comparative Examples 1 to 4 having different cladding compositions and MFR values, the adhesion, translucency, bending resistance, and other physical property balances were poor.

[Example 7]
As shown in Table 1, a POF cord was obtained in the same manner as in Example 1 except that a two-layer structure of the first clad and the second clad was used (however, the fiber diameter was unified to 1000 μm). These POF codes were used for the same evaluation as in Example 1, and the results are shown in Table 2.

  In Example 7 of the present invention, the adhesion between the fiber and the first coating layer was high, and all of the translucency, bending resistance, heat resistance, moist heat resistance, and bending resistance were excellent.

[Comparative Examples 5-6]
As shown in Table 1, a POF cord was obtained in the same manner as in Example 1 except that a two-layer structure of the first clad and the second clad was used (however, the fiber diameter was unified to 1000 μm). These POF codes were used for the same evaluation as in Example 1, and the results are shown in Table 2.

  On the other hand, Comparative Examples 5 to 6 having different cladding compositions and configurations had poor adhesion, flex resistance, and other physical property balances.

PMMA: Polymethyl methacrylate MMA: Methyl methacrylate 3FM: 2,2,2-trifluoroethyl methacrylate 4FM: 2,2,3,3-tetrafluoropropyl methacrylate 5FM: 2,2 , 3,3,3-pentafluoropropyl methacrylate 17FM: 1,1,2,2-tetrahydroperfluorodecyl methacrylate 2F: vinylidene fluoride 4F: tetrafluoroethylene 6F: hexafluoropropylene

Claims (5)

Plastic light having a core / cladding two-layer structure having a core made of a polymer mainly composed of methyl methacrylate and a clad layer made of an organic polymer having a refractive index smaller than the refractive index of the core on the outer periphery of the core In the fiber, a plastic optical fiber characterized in that the copolymer forming the cladding layer contains the following components, and the copolymer has a melt flow rate (MFR) value of 5 to 24 g / 10 min. .
Vinylidene fluoride: 52-72 mol%
Tetrafluoroethylene: 26-46 mol%
Hexafluoropropylene: 2-8 mol% Three layers of core / first clad / second clad having a core made of a polymer mainly composed of methyl methacrylate and a clad layer in which the first clad and the second clad are sequentially laminated on the outer periphery of the core. In structure plastic optical fiber,
The first cladding is of formula (1)
_{CH 2 = C (CH 3)} -COOCH 2 (CF 2) n R (1)
(However, R represents a fluorine atom or a hydrogen atom, and n represents an integer of 1 to 4.)
And a copolymer containing 40 to 90 mol% perfluoroalkyl methacrylate and 10 to 60 mol% methyl methacrylate as a copolymerization component, and the second clad contains the following components, and A plastic optical fiber comprising a copolymer having a melt flow rate (MFR) value of 5 to 24 g / 10 min.
Vinylidene fluoride: 52-72 mol%
Tetrafluoroethylene: 26-46 mol%
Hexafluoropropylene: 2-8 mol%   3. The plastic optical fiber cord according to claim 1, further comprising one or more coating layers on the outer periphery of the plastic optical fiber, wherein the coating layer is made of a thermoplastic resin.   The plastic optical fiber cord according to claim 3, wherein the thermoplastic resin is a resin mainly composed of nylon 12 or polypropylene.   The plastic optical fiber cord according to claim 3 or 4, wherein an adhesion force between the plastic optical fiber and the coating layer in contact with the outer periphery thereof is 50 N or more.