JPH1195044A - High na plastic optical fiber and cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten NA and reduce a light quantity loss caused by bending so as to increase the light receiving quantity by using specific sheath resin with a low refractive index to form a high NA plastic optical fiber. SOLUTION: An uncovered high NA plastic optical fiber 5 has a core 1 formed of polymethyl methacrylate resin, and a sheath 2 formed of resin containing a vinylidene fluoride component at 30-92 mol.%, a tetrafluoroethylene component at 0-55 mol.% and a hexafluoropropylene component at 8-25 mol.%, with a refractive index measured at 25 deg.C by a sodium D-line being 1.350-1.380, the Shore D hardness value at 23 deg.C being 30-55, and a melt flow index (under the conditions of 230 deg.C, 3.8 kg in load, 2 mm in orifice diameter and 8 mm in length) showing a fluidity of 5 g/10 min.-100 g/10 min. The outside of a bare optical fiber 5 of a high NA plastic optical fiber with theoretical NA of 0.57 is covered with a protection layer formed of vinyliden fluoride resin with a fusing point of 120 deg.C or higher and a Vicat softening point of 110 deg.C or higher, in close contact in a thickness of 2 μm-300 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical fiber used for optical signal transmission such as on-vehicle wiring, mobile wiring, FA equipment wiring, personal computer wiring, and photoelectric sensors.

[0002]

2. Description of the Related Art As a sheath resin of a plastic optical fiber having a core of a polymethyl methacrylate resin (hereinafter referred to as "PMMA resin"), a fluoroalkyl methacrylate copolymer is known. Tokuhei 7-1
Japanese Patent Application Laid-Open No. 1605 discloses such a sheath resin, whose refractive index is at most about 1.40. Further, a copolymer of vinylidene fluoride and tetrafluoroethylene,
Particularly, a binary copolymer having a copolymer composition of 80 mol% / 20 mol% and a refractive index of 1.403 is famous. Vinylidene fluoride, tetrafluoroethylene and hexafluoropropene copolymers are also known, and are disclosed in JP-B-62-340.
No. 1 proposes a copolymer comprising vinylidene fluoride, tetrafluoroethylene, and an unsaturated polymerizable compound, but plastic optical fiber products actually using these sheaths are still in practical use in the market. It has not been.

[0003]

In recent years, many plastic optical fibers have been used for relatively short distances, such as light guides, photoelectric sensors, short-distance wiring in automobiles, audio wiring, and FA wiring. However, the problem is that the theoretical N
Since A is about 0.55 or less, there is a problem that the loss when the plastic optical fiber is bent is large. In addition, when used for light guides and photoelectric sensors,
There is a problem that the amount of received light is small. In the case of wiring in automobiles and network wiring, in addition to the problem of optical loss due to bending wiring when laying, the problem of coupling loss when branching or coupling optical fibers is closed. It is up, but N of plastic optical fiber
In fact, no special review of A has been made in the last 10 years.

[0004]

According to the present invention, there is firstly provided a core comprising a polymethyl methacrylate resin, a terpolymer comprising vinylidene fluoride, tetrafluoroethylene and hexafluoropropene or vinylidene fluoride and hexafluoropropene. A binary copolymer of fluoropropene,
The vinylidene fluoride component is in the range of 30 to 92 mol%, the tetrafluoroethylene component is in the range of 0 to 55 mol%, and the hexafluoropropene component is in the range of 8 to 25 mol%. .350 to 1.38
Shore D hardness at 23 ° C. (AST
MD2240) is in the range of 30 to 55, and the melt flow index (230 ° C., load 3.8 kg, orifice diameter 2 mm, length 8 mm condition) is 5 g / 10.
Having a melting point of 120 ° C. or more and outside of a high NA plastic optical fiber bare wire having a theoretical NA of 0.57 or more, having a melting point of 120 ° C. or more. Softening temperature (ASTM D1525) is 1
This is a high NA plastic optical fiber coated with a protective layer made of vinylidene fluoride resin at a temperature of 10 ° C. or higher in close contact with a thickness of 2 μm to 300 μm.

In a second aspect of the present invention, the resin for forming the sheath contains 40 to 62 mol% of a vinylidene fluoride component,
The tetrafluoroethylene component is in the range of 28 to 40 mol%, the hexafluoropropene component is in the range of 8 to 22 mol%,
It is a plastic optical fiber having a Shore D hardness at 3 ° C. (ASTM D2240) in the range of 35 to 45.

In a third aspect of the present invention, there is provided a high NA plastic optical fiber in which a protective layer made of nylon 12 or nylon 11 is coated on the outside of the bare high NA plastic optical fiber in a thickness of 2 μm to 300 μm. It is a fiber strand.

In a fourth aspect of the present invention, the resin forming the sheath comprises 40 to 62 mol% of a vinylidene fluoride component, 28 to 40 mol% of a tetrafluoroethylene component, and 8 to 22 mol% of a hexafluoropropene component. % Shore D hardness at 23 ° C. (ASTM D224
0) is a plastic optical fiber in the range of 35 to 45.

A fifth invention is a high NA plastic optical fiber in which the protective layer resin is a black light shielding resin in the above element.

A sixth invention is a high-NA plastic optical fiber cable in which a coating layer made of polyethylene is formed outside the bare wire.

In a seventh aspect, the resin forming the sheath is as follows:
The vinylidene fluoride component is in the range of 40 to 62 mol%, the tetrafluoroethylene component is in the range of 28 to 40 mol%, the hexafluoropropene component is in the range of 8 to 22 mol%, and the Shore D hardness at 23 ° C. (ASTM D2240) is 35 to
45 is a plastic optical fiber cable in the range of 45.

An eighth invention is a high NA plastic optical fiber cable in which a coating layer made of a thermoplastic resin is formed outside the above-mentioned wire, and a ninth invention is that the thermoplastic resin is made of a polyamide resin. A tenth aspect of the present invention is a high NA plastic optical fiber cable having a coating layer formed thereon, wherein the polyamide resin coated cable is used for in-vehicle wiring.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS It is known that the PMMA resin used in the present invention has high reliability as a core of a plastic optical fiber. The PMMA resin used in the present invention is a homopolymer of methyl methacrylate (PMMA) or a copolymer containing 50% by weight or more of methyl methacrylate, and as copolymerizable components, methyl acrylate, ethyl acrylate, acrylic acid Acrylates such as butyl, ethyl methacrylate, propyl methacrylate,
Methacrylates such as cyclohexyl methacrylate, maleimides such as isopropylmaleimide,
There are acrylic acid, methacrylic acid, styrene and the like, and one or more of them are appropriately selected and copolymerized.

As a sheath resin, a fluoroalkyl methacrylate copolymer has been used in communication applications and FA applications since it maintains a stable transmission loss value with heat resistance. However, the refractive index of these sheath resins is 1.42-1.
It is around 40. The theoretical NA is represented by the square root of the difference between the square of the refractive index of the core resin and the square of the refractive index of the sheath resin.
When the refractive index measured with the sodium D line in the above is used as an index, the upper limit of NA is about 0.52. On the other hand, a resin practically used as a vinylidene fluoride resin is a copolymer comprising 80 mol% of vinylidenefluoride and 20 mol% of tetrafluoroethylene and having a refractive index of 1.40.
3 or a copolymer of vinylidene fluoride, trifluoroethylene and hexafluoroacetone having a refractive index of 1.4.
The resin had a NA of about 0.52.

A plastic optical fiber cable using the above-described sheath resin is formed by attaching one rod to a rod having a bending radius of 10 mm.
The current situation is that a loss of about 2 dB is generated only by winding the wire twice. Therefore, in the case of wiring to a network in an automobile, for example, the fiber is routed in a very narrow space, and the optical loss due to the bending is a serious problem.

It has been found that raising the NA is effective in reducing the optical loss due to bending of the fiber, but the attempt has not been successful, and currently a low NA fiber is still used. . On the other hand, there is also a demand for increasing the amount of received light as much as possible in applications such as light guides and photoelectric sensors. It is also known that the amount of light that can be received by an optical fiber is roughly proportional to the square of NA. Therefore, a plastic optical fiber with a high NA is desired. However, a plastic optical fiber having a core made of PMMA resin has been put into practical use. There is a reality that none of the above-mentioned fibers has an NA exceeding 0.55.

An object of the present invention is to provide a plastic optical fiber which has a small bending loss and which can withstand use in a severe environment. Specifically, it has a large theoretical NA and is excellent in heat resistance and chemical resistance. Plastic optical fibers and cables.

The present inventors have conducted intensive studies to develop an optical fiber having a high NA. As a result, a terpolymer composed of vinylidene fluoride, tetrafluoroethylene and hexafluoropropene or a terpolymer composed of vinylidene fluoride and hexafluoropropene has been developed. A binary copolymer having a vinylidene fluoride component content of 30 to 92 mol%, a tetrafluoroethylene component content of 0 to 55 mol%, and a hexafluoropropene component content of 8 to 55 mol%;
25% and the melt flow index (23
A resin exhibiting a fluidity of 5 g / 10 min to 100 g / 10 min at 0 ° C., load 3.8 kg, orifice diameter 2 mm and length 8 mm) has a refractive index of 1.350 measured at 20 ° C. with sodium D line. It was found that a plastic optical fiber having a very high NA of about 0.60 can be obtained when the sheath is formed with the resin and the core is a PMMA-based resin. However, since the sheath resin has low hardness and inferior heat resistance, the bare wire formed using the sheath resin cannot withstand actual use. Therefore, as a result of further study by the present inventors, if this is coated with polyethylene resin and used as a cable,
At least 80 ° C and 95% humidity
It has been found that transmission loss does not increase over a long period of about 00 hours.

In order to withstand use as a plastic optical fiber, the sheath resin cannot be put to practical use if it is too soft. If the sheath resin is too soft, the sheath is sticky and the bare wires are fused together, cannot be wound around a bobbin, the sheath flows due to mechanical tightening, and the reliability of the fiber is impaired. Therefore, the Shore hardness (ASTM D2240) of the sheath resin used in the present invention is in the range of 30 to 55 at 23 ° C. In addition, a preferred resin that satisfies the refractive index, transparency, and hardness more preferably has a vinylidene fluoride component of 40 to 62 mol%, a tetrafluoroethylene component of 28 to 40 mol%, and a hexafluoropropene component of 8 to 22 mol%. Shore D at 23 ° C
A resin having a hardness (ASTM D2240) in the range of 35 to 45.

In the present invention, when the above-mentioned resin having a Shore hardness of less than 35 is used as the sheath resin, when the core and the sheath are compositely spun and the bare wire is wound, the bare wire is difficult to unwind. The cable of the present invention can be manufactured without any trouble by continuously coating with a polyethylene resin without removing the cable.

The content of each component of the sheath resin used in the present invention can be measured by NMR. In particular,
A sample solution was prepared by dissolving an appropriate amount of the sheath resin sample in a mixed solvent of acetone-d6 and α, α, α-trifluorotoluene. The observation frequency was 400 MHz for ¹ H and 37 F for ¹⁹ F.
6 MHz, ¹ H-NM
R is converted based on tetramethylsilane, ¹⁹ F-NMR
Was converted based on trichlorofluoromethane. The calculation of the concentration of each component from the spectrum is performed by converting the composition of weight% obtained by the following equation into mol%.

[0021]

(Equation 1)

In the above formula, A: the number of mmol of trifluorotoluene in the sample solution B: 2.2 to 2.7 ppm and 3.0 to 3.0 ppm by ¹ H-NMR.
3.8 ppm total integrated value C: 7.0-8.5 ppm integrated value by ¹ H-NMR D: mg number of sample in sample solution E: -67 to -78 ppm integrated value by ¹⁹ F-NMR F: Integrated value of -62 to -66 ppm by ¹⁹ F-NMR

FIG. 1 is a schematic sectional view of one embodiment of the plastic optical fiber cable of the present invention. In the figure, 1 is a core, 2 is a sheath, 4 is a coating layer, 5 is a bare plastic optical fiber, and 7 is a plastic optical fiber cable.
In the cable, the diameter of the core 1 is 200 to 3000.
μm, the thickness of the sheath 2 is 2 to 50 μm, and the thickness of the coating layer 4 is 2 μm.
Preferably, the core 1 has a diameter of 4 to 1000 μm.
The thickness of the sheath 2 is preferably 80 to 1480 μm, the thickness of the sheath 2 is 5 to 25 μm, and the thickness of the coating layer 4 is preferably 100 to 1000 μm.

Further, in the present invention, a specific heat-resistant resin is composed of a core made of a PMMA resin and a sheath made of the above specific resin so that the sheath and the protective layer are fused and strongly adhered to each other so that pistoning does not occur. If the cable is coated with a thermoplastic resin on the outside of the bare wire to be thinly protectively coated, and the cable is coated with a thermoplastic resin, the change in dimension is small even at a temperature of 100 ° C to 110 ° C, and the transmission loss value is stable. The inventors have also found that a heat-resistant cable can be obtained and completed the present invention.

FIG. 2 is a schematic sectional view of one embodiment of the plastic optical fiber cable. The same members as those in FIG. 1 are denoted by the same reference numerals. In the drawing, reference numeral 3 denotes a protective layer, and reference numeral 6 denotes a plastic optical fiber. Also in this cable, preferable ranges of the diameter of the core 1 and the thickness of the sheath 2 are the same as those of the cable shown in FIG.

The first of the plastic optical fiber strands of the present invention is that, outside the bare plastic optical fiber of the present invention,
It has a melting point of 120 ° C or higher and has a Vicat softening temperature (AS
A protective layer of a vinylidene fluoride-based resin having TMD 1525) of 110 ° C. or higher is coated to a thickness of 2 μm to 300 μm. Here, the Vicat softening temperature is ASTM D1
This refers to the temperature when the needle is pierced at a depth of 1 mm at a load of 1.0 kg and a heating rate of 2 ° C./min according to 525.

In the strand of the present invention, as the vinylidene fluoride resin as the protective layer resin, vinylidene fluoride was grafted onto polyvinylidene fluoride or a random copolymer of polyvinylidene fluoride-chlorotrifluoroethylene. Copolymer, polyvinylidene fluoride-tetrafluoroethylene copolymer, polyvinylidene fluoride-hexafluoropropene copolymer, polyvinylidene fluoride-tetrafluoroethylene-hexafluoropropene copolymer, polyvinylidene fluoride-chloro Melting point of 120 ° C among trifluoroethylene copolymers
A heat-resistant resin having the above crystallinity, the copolymer of which has a vinylidene fluoride structural component more preferably of 50% by weight or more, protects the optical fiber by bonding the sheath layer and the protective layer together. . In other words, the high melting point of the protective layer and the resin with a high heat distortion temperature closely adhere to the bare wire of the plastic optical fiber and reinforce it, suppressing dimensional shrinkage due to heating,
Plays a role in protecting bare wires from external mechanical damage.

The plastic optical fiber of the present invention is not only safely protected from dimensions and structural damage such as deformation from the side by the protective layer, but also optically has the original sheath resin. Since the crystallinity is essentially low and the transparency is high, the transmission loss is stable, and the protective layer resin itself has excellent oil resistance, so the influence of external plasticizers and additives should be reduced. Can be done. for that reason,
A plastic optical fiber can withstand a temperature of 100 ° C. to 110 ° C., which cannot be expected from the low hardness and low heat deformation temperature of the original sheath resin.

The second of the plastic optical fiber strands of the present invention has a protective layer formed of nylon 12 and nylon 11, similarly to the first strand, and has heat resistance and close adhesion with the sheath layer. Is shown. Nylon resin also adheres firmly to the sheath of the bare wire of the present invention, and if it is to be peeled off, the fiber will be stretched, and it is effective as a protective layer resin.

There are two methods for producing the strand of the present invention. One is that the core, the sheath and the protective layer are simultaneously spun by composite spinning. In this case, the heat-resistant resin of the protective layer is 1.3 to 5 times for increasing the strength of the PMMA resin fiber. A degree of stretching and annealing are performed. Although this method is excellent in productivity, since the heat-resistant resin is stretched, in the case of a resin having an extremely high melting point, the stretching distortion is large, and the fiber may be contracted by heating. Therefore, the melting point of the protective layer resin is 12
It is preferable to use a vinylidene fluoride resin having a relatively low melting point of about 0 ° C to 140 ° C.

The second method is to obtain a bare wire, and then coat the bare wire with a protective layer in the same manner as in covering an electric wire. In this case, since the protective layer is not stretched, the protective layer resin is a vinylidene fluoride resin having a melting point of 150 to 180.
It is convenient to coat a protective layer of a heat-resistant resin having a relatively high temperature of about ° C, for example, nylon 12 or nylon 11.

The protective layer is usually used without special coloring, but it is also possible to color this layer with a pigment. Above all, when colored black with a pigment such as carbon black so that light can be shielded, a colored coating layer other than black, such as yellow, red, or white, is formed thereon to obtain a colorful cable. When light shielding is performed using carbon black, the thickness (μm) of the light shielding layer and the carbon black content (pp
If the product of m) is 10000 ppm · μm or more, the invasion of the direct sunlight can be substantially prevented, and a colorful coating can be freely applied thereon to facilitate identification and enhance fashionability.

The strand of the present invention can be used as it is as a cable with a thin coating as it is, but it is thicker to impart mechanical strength such as stepping on, to insert a tension member, and to enhance fashionability. By providing a coating layer, the cable can be used as a more complete cable. Examples of the thermoplastic resin for forming the coating layer include a polyethylene resin, a halogen-free flame-retardant polyethylene resin, a polyvinyl chloride resin, a polyester resin, a polyurethane resin, a polyamide resin, and a polyolefin elastomer resin. Can be used. In the present invention, the thickness of the coating layer is preferably from 20 to 1000 μm, and more preferably from 100 to 1000 μm.

Above all, a polyamide resin is preferable for imparting heat resistance and oil resistance to the cable.

In particular, a cable in which nylon 12 or nylon 11 is coated on a wire having a protective layer made of vinylidene fluoride resin has extremely high durability against vehicle oils such as gasoline, light oil and engine oil. high,
It is suitable for wiring in automobiles because it has a high mechanical tensile strength with stable transmission loss value even at heat resistance and 105 ° C., very strong against repeated bending, and little light loss due to bending.

A cable in which nylon is further coated on a strand having a protective layer made of nylon 12 or 11 is similarly used as a cable having excellent oil resistance for use in automobiles and FA.
It is suitable for applications or for sensors. Also, the cable coated with vinyl chloride resin on the strand having a protective layer made of vinylidene fluoride resin has a protective layer made of vinylidene fluoride resin that prevents plasticizer from migrating and has excellent transmission loss value. Guarantee the quality.

[0037]

Embodiments will be described below with reference to embodiments.

Example 1 The refractive index n _d20 was 1.492,
Melt flow index 230 ° C, load 3.8K
g, orifice diameter 2 mm, length 8 mm,
Polymethyl methacrylate resin (PMMA) of 1.5 g / 10 min was used as the core resin. As sheath resin,
A copolymer consisting of 57 mol% of vinylidene fluoride, 31% of tetrofluoroethylene and 12% of hexafluoropropene, and has a melt flow index at 230 ° C. and a load of 3.8 Kg of 30 g / 10 min and a refractive index of 1.364 at a load of 3.8 kg. Shore D hardness at ℃ (ASTM D2240)
Was used. This sheath resin was excellent in transparency. Regarding the content of each component of the sheath resin, 9 to 100 parts by weight of a mixed solvent composed of 91 parts by weight of acetone-d6 and 9 parts by weight of α, α, α-trifluorotoluene was added with 9 to 10 parts by weight of the sheath resin.
Using the sample solution prepared by precisely weighing and dissolving 10 parts by weight, as described above, the above core resin and sheath resin determined by NMR were supplied to the composite spinning die, and the strand discharged from the die was subjected to 2 It was stretched twice and heat-treated to obtain a bare plastic optical fiber having a core diameter of 980 µm and a sheath outer diameter of 1000 µm. Further, the bare wire was coated with black polyethylene in a continuous cable forming step without winding it up on a bobbin to obtain a plastic optical fiber cable having a diameter of 2.2 mm.
The theoretical NA of this cable is 0.60.

The transmission loss of this plastic optical fiber cable was 129 dB / km when measured at an incident NA of 0.15 at a wavelength of 650 nm. Place this plastic optical fiber cable in an oven at 80 ° C and 95% humidity.
The transmission loss value when left for 00 hours is 165 dB / km
And was stable. The projecting retraction of the bare wire of this cable and the polyethylene jacket was a retraction of 0.5 mm.

As another experiment, a Shore D hardness at 23 ° C., a tensile elongation at break of 400%, and a melting point of 170 were obtained outside the bare plastic optical fiber of this example.
A vinylidene fluoride resin having a Vicat softening temperature of 125 ° C and a coating material was coated to a thickness of 200 µm to obtain a plastic optical fiber having a diameter of 1.4 mm. A heat-resistant vinyl chloride resin is coated on the wire, and the diameter is 2.2.
mm plastic optical fiber cable was obtained.

Place the above cable in a thermostat at 110 ° C. for 100
The transmission loss when left for 0 hours is 13 before the test.
In contrast to 0 dB / km, it was stable at 150 dB / km after the test. In addition, the element wire and the bare wire were in close contact and integrated with each other, and the projecting and retracting of the tip portion was 0. The projecting retraction between the strand and the vinyl chloride resin jacket was only a protrusion of 0.2 mm, and the heat resistance of the plastic optical fiber cable was sufficiently secured.

[Example 2] The core resin and the sheath resin were obtained in Example 1.
The same one was used. The protective layer is a copolymer of vinylidene fluoride 80 mol% and tetrafluoroethylene 20 mol%, and has a melt flow index of 30 g / 10.
Minutes of resin was used. The melting point of this resin was 127 ° C, and the Vicat softening temperature was 119 ° C.

The three resins of the core resin, the sheath resin, and the protective layer resin were introduced into a three-layer composite spinning die, and the obtained strand was stretched by a factor of two and further annealed to obtain a core diameter of 970.
A plastic optical fiber having a diameter of μm, a sheath outer diameter of 985 μm, and a strand outer diameter of 1000 μm was obtained. The transmission loss of this wire was 650 nm and was measured at an incident NA of 0.15.
It was 5 dB / km. Further, the transmission loss value when the present plastic optical fiber was left in an oven at 80 ° C. and a humidity of 95% for 1000 hours was stable at 160 dB / km.

Next, nylon 12 was coated on the strand to obtain a cable having a diameter of 2.2 mm. The transmission loss value of this cable was 135 dB / km. The transmission loss after leaving this cable in a thermostat at 105 ° C. for 1000 hours was 145 dB / km, which was almost the same as before the test.

Further, the projecting and retracting of the strand and the nylon jacket at the end of the cable was only 0.1 mm. Furthermore, the overall cable dimensions are 99.4
% Retained.

To further examine the oil resistance, the tip was immersed in light oil and gasoline for 500 hours at 23 ° C. without touching the oil directly. There was no. Thus, this cable was preferable as an in-vehicle cable.

Comparative Example 1 A copolymer consisting of 80 mol% of vinylidene fluoride and 20 mol% of tetrofluoroethylene having a refractive index of 1.403 and a Shore D hardness of 60 was used as the sheath resin. A plastic optical fiber cable coated with polyethylene was obtained in the same manner as in Example 1.
The transmission loss was 130 dB / km measured at a wavelength of 650 nm and an incident NA of 0.15.

This plastic optical fiber cable is
The transmission loss value when left in an oven at 95 ° C. and a humidity of 95% for 1000 hours increased to 380 dB / km.

Example 3 The loss of light amount due to bending of the plastic optical fiber cable of Example 2 and the plastic optical fiber cable of Comparative Example 1 and the difference in the amount of light received from the LED were measured.

Each optical fiber cable was taken 2 m, and the center was a standard rod (radius: 5 mm, 10 mm, 15 mm).
(mm, 20 mm) at 360 ° once. For the measurement, Hakutronics (Hakut
(photonics 205 manufactured by Ronics). One of the light sources is an LED with an incident NA of 0.6 or more built into the power meter, and the other is an LED with an incident NA of 0.2 ("NL2" manufactured by NEC Corporation).
100 "). Table 1 shows the results.

[0051]

[Table 1]

Example 4 On the bare plastic optical fiber obtained in Example 1, black nylon 12 containing 500 ppm of carbon black was protectively coated to a thickness of 50 μm by a wire coating method to obtain a diameter of 1 μm. A .1 mm strand was obtained. The transmission loss of this strand was 129 dB / km when measured at an incident NA of 0.15 at a wavelength of 650 nm. Place this plastic optical fiber in an oven at 100 ° C.
The transmission loss value when left for 000 hours is 145 dB / k
m and stable. In this element wire, the nylon coating adhered firmly to the sheath like an enameled wire and did not peel off. Therefore, it has been found that this thin wire can be suitably used for a photoelectric sensor as a thin heat-resistant cable having a light shielding layer.

Example 5 One piece of black nylon 12 containing 500 ppm of carbon black was coated on the plastic optical fiber obtained in Example 2 by an electric wire coating method.
Protective coating was applied to a thickness of 50 μm to obtain a 1.3 mm-diameter coated nylon small-diameter cable. Further, a yellow nylon 12 resin was coated thereon by an electric wire coating method, and the diameter was 2.
A 2 mm cable was obtained. The transmission loss of this cable is 13
It was 5 dB / km. When the coating of the cable was peeled off with a wire stripper, the yellow and black nylon layers could be peeled off. However, in the case of Example 4, the nylon directly coated on the sheath layer was not capable of peeling because of strong adhesion to the sheath, whereas in the present embodiment, the protective layer was formed of vinylidene fluoride 80 This is because it is a copolymer composed of mol% and 20 mol% of tetrafluoroethylene and is not fused to the nylon layer.

The cable was taken 50 m, black connectors were connected to both ends thereof, and the cable was exposed to direct sunlight using a toslink tester, and the amount of light received by the sample cable from outside the coating was measured. During this time, the power was measured without turning on the LED. As a result, -40 dBm
It was just the following light leakage. Next, this cable was immersed in light oil and gasoline at 23 ° C. for 500 hours, but there was no change in the transmission loss of the plastic optical fiber and no corrosion of the cable.

Using this cable at 105 ° C. for 1000
A heat resistance test was performed for a long time, but the transmission loss was 140 dB /
It was stable at km.

This cable was preferable as a cable for a vehicle.

Example 6 A core diameter of 940 μm and a sheath outer diameter of 960 μm were obtained using the same core resin and sheath resin as in Example 1.
A black plastic wire containing 1000 ppm of carbon black, a Shore D hardness at 23 ° C. of 74, a tensile elongation at break of 400%, a melting point of 170 ° C., and a Vicat softening temperature by a wire coating method on a bare plastic optical fiber. Is 1
A coating of a vinylidene fluoride resin at 25 ° C. was applied to a thickness of 20 μm to obtain a plastic optical fiber having a diameter of 1.0 mm. A yellow nylon 12 resin is coated on the wire by a wire coating method to have a diameter of 2.2 mm.
Got the cable. The transmission loss of this cable is 133dB
/ Km. When the coating of the cable was peeled off with a wire stripper, the yellow nylon layer was peeled off and the black protective layer remained.

The above cable was taken 50 m, black connectors were connected to both ends of the cable, and the cable was exposed to direct sunlight using a toslink tester, and the amount of light received by the sample cable from outside the coating was measured. During this time, the power was measured without turning on the LED. The result is -35 dBm
It was just the following light leakage. Next, this cable was immersed in light oil and gasoline for 500 hours at 23 ° C., but there was no change in the transmission loss of the plastic optical fiber.
There was no corrosion of the cable. 10 using this cable
A heat resistance test was performed at 5 ° C. for 1000 hours, and the transmission loss was stable at 138 dB / km.

This cable was preferable as an in-vehicle cable.

Example 7 The refractive index n as the core resin
_{A d20} 1.492 PMMA having a melt flow index of 1.5 g / 10 min was used. As the sheath resin, vinylidene fluoride 45 mol%, tetrafluoroethylene 35 mol%, hexafluoropropene 20 mol%,
The melt flow index is 25 g / 10 min, the refractive index is 1.355, and the Shore D hardness at 23 ° C. (ASTM)
D2240) was used. This resin was excellent in transparency. The content of each component of the sheath resin was measured according to the measurement method described in Example 1.

As the protective layer, vinylidene fluoride 8
A sheath resin containing 0 mol% and 20 mol% of tetrafluoroethylene and having a melt flow index of 30 g / 10 min was used. The melting point of this resin is 127 ° C and the Vicat softening temperature is 1
19 ° C.

The core resin, the sheath resin and the protective layer resin are introduced into a three-layer composite spinning die, the obtained strand is stretched by a factor of two, and annealed, and the core diameter is 970 μm, the sheath outer diameter is 985 μm, and the strand is A plastic optical fiber having an outer diameter of 1000 μm was obtained. The transmission loss of this wire was 135 dB / km measured at an incident NA of 0.15 at a wavelength of 650 nm.
Met. The transmission loss when this strand is left in an oven at 80 ° C. and 95% humidity for 1000 hours is 170 dB / km.
And was stable.

The outside of the strand was covered with nylon 12 to obtain a 2.2 mm cable. The transmission loss of this cable was 140 dB / km. When this cable was left in a thermostat at 105 ° C. for 1000 hours, the transmission loss was 146 dB / km, which was almost the same as before the test. Further, the projecting retraction between the strand and the nylon jacket at the end of the cable was only 0.2 mm. In addition, the overall cable dimensions were maintained at 99.4%. To further examine the oil resistance, the tip was immersed in light oil and gasoline for 500 hours at 23 ° C. without touching the oil directly, but there was no change in the transmission loss of the plastic optical fiber and no corrosion of the cable. . As described above, the cable of the present embodiment was preferable as a cable for a vehicle.

[0064]

As described above, since the plastic optical fiber and the cable of the present invention are formed by using a sheath resin having a low refractive index, a conventional fiber using a PMMA resin as a core can be used. Compared with this, the NA was greatly increased, the loss of light amount due to bending was significantly reduced, and the amount of received light was able to be increased. As described above, the sheath resin has low hardness and low heat resistance, but by forming a cable formed with a coating layer of a polyethylene resin, it prevents deformation, increases heat resistance, and withstands use. I was able to. Also, vinylidene fluoride resin or nylon 11, 12
By using a wire having a protective layer made of a heat-resistant resin such as a cable, or a cable provided with a coating layer made of a thermoplastic resin on the wire, a wire having high heat resistance, moisture resistance, and chemical resistance can be obtained. Wiring that can withstand use even in harsh and narrow environments such as in an automobile is realized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of one embodiment of a high NA plastic optical fiber cable of the present invention.

FIG. 2 is a schematic sectional view of another embodiment of the high NA plastic optical fiber cable of the present invention.

[Explanation of symbols]

 Reference Signs List 1 core 2 sheath 3 protective layer 4 coating layer 5 bare plastic optical fiber 6 plastic optical fiber bare wire 7 plastic optical fiber cable

Claims (10)

[Claims] 1. A core comprising a polymethyl methacrylate resin and a terpolymer comprising vinylidene fluoride, tetrafluoroethylene and hexafluoropropene or a copolymer comprising vinylidene fluoride and hexafluoropropene
A copolymer having a vinylidene fluoride component of 30
９２92 mol%, tetrafluoroethylene component in the range of 0-55 mol%, hexafluoropropene component in the range of 8-25 mol%, and a refractive index of 1.350-1.380 measured at 25 ° C. with sodium D line. And the value of the Shore D hardness at 23 ° C. (ASTM D2240) is 30 to 5
5 and the melt flow index (230
° C, load 3.8Kg, orifice diameter 2mm, length 8
mm condition) having a sheath made of a resin having a flowability of 5 g / 10 min to 100 g / 10 min, and a high NA plastic optical fiber bare wire having a theoretical NA of 0.57 or more.
It has a melting point of 120 ° C or higher and has a Vicat softening temperature (AS
TM D1525) is a high NA plastic optical fiber coated with a protective layer made of a vinylidene fluoride resin having a temperature of 110 ° C. or higher in a thickness of 2 μm to 300 μm. 2. The resin forming the sheath is in the range of 40 to 62 mol% of vinylidene fluoride component, 28 to 40 mol% of tetrafluoroethylene component and 8 to 22 mol% of hexafluoropropene component, The plastic optical fiber according to claim 1, wherein the Shore D hardness at 23 ° C (ASTM D2240) is in the range of 35 to 45. 3. A core comprising a polymethyl methacrylate resin and a terpolymer comprising vinylidene fluoride, tetrafluoroethylene and hexafluoropropene or a copolymer comprising vinylidene fluoride and hexafluoropropene.
A copolymer having a vinylidene fluoride component of 30
９２92 mol%, tetrafluoroethylene component in the range of 0-55 mol%, hexafluoropropene component in the range of 8-25 mol%, and a refractive index of 1.350-1.380 measured at 25 ° C. with sodium D line. And the value of the Shore D hardness at 23 ° C. (ASTM D2240) is 30 to 5
5 and the melt flow index (230
° C, load 3.8Kg, orifice diameter 2mm, length 8
mm condition) having a sheath made of a resin having a flowability of 5 g / 10 min to 100 g / 10 min, and a high NA plastic optical fiber bare wire having a theoretical NA of 0.57 or more.
2 μm to 3 μm of protective layer made of nylon 12 or 11 resin
High NA plastic optical fiber coated in close contact with a thickness of 00 μm. 4. The resin forming the sheath is in the range of 40 to 62 mol% of vinylidene fluoride component, 28 to 40 mol% of tetrafluoroethylene component, and 8 to 22 mol% of hexafluoropropene component, The plastic optical fiber according to claim 3, wherein the Shore D hardness at 23 ° C (ASTM D2240) is in the range of 35 to 45. 5. The high NA plastic optical fiber according to claim 1, wherein said protective layer is made of a black light shielding resin. 6. A core comprising a polymethyl methacrylate resin and a terpolymer comprising vinylidene fluoride, tetrafluoroethylene and hexafluoropropene or a terpolymer comprising vinylidene fluoride and hexafluoropropene.
A copolymer having a vinylidene fluoride component of 30
９２92 mol%, tetrafluoroethylene component in the range of 0-55 mol%, hexafluoropropene component in the range of 8-25 mol%, and a refractive index of 1.350-1.380 measured at 25 ° C. with sodium D line. And the value of the Shore D hardness at 23 ° C. (ASTM D2240) is 30 to 5
5 and the melt flow index (230
° C, load 3.8Kg, orifice diameter 2mm, length 8
mm condition) having a sheath made of a resin having a flowability of 5 g / 10 min to 100 g / 10 min, and a high NA plastic optical fiber bare wire having a theoretical NA of 0.57 or more.
A high NA plastic optical fiber cable having a coating layer made of polyethylene. 7. The resin forming the sheath is in the range of 40 to 62 mol% of vinylidene fluoride component, 28 to 40 mol% of tetrafluoroethylene component, and 8 to 22 mol% of hexafluoropropene component, The plastic optical fiber cable according to claim 5, wherein the Shore D hardness at 23 ° C (ASTM D2240) is in the range of 35 to 45. 8. A high-NA plastic optical fiber cable in which a coating layer made of a thermoplastic resin is formed on the outside of the plastic optical fiber strand according to claim 1. 9. The plastic optical fiber cable according to claim 8, wherein said thermoplastic resin is a polyamide resin. 10. The plastic optical fiber cable according to claim 9, which is used as wiring in an automobile.