JP2000231045A - Plastic optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic optical fiber cable having satisfactory flame resistance as well as solvent resistance. SOLUTION: A primary coating layer comprising a nylon resin having <=200 deg.C melting point is disposed on the periphery of a plastic optical fiber and a secondary coating layer comprising a resin having an oxygen index of >=25 is disposed on the periphery of the primary coating layer. The thickness of the primary coating layer is >=100 μm and the thickness (t2) of the secondary coating layer and the average outside diameter (d1) of the primary coating layer satisfy the relation of 0.1<=t2/d1<=1.6.

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 cable which is excellent in oil resistance and flame retardancy and is suitable for communication in a moving vehicle such as a vehicle and a railway.

[0002]

2. Description of the Related Art Plastic optical fibers have a large diameter and are easy to process, and precise processing accuracy is not required for peripheral devices such as connectors. Therefore, plastic optical fibers themselves, their peripheral devices, and construction costs, etc. Are inexpensive, and thus are being used for short-distance communication media of 100 m or less, sensors, and the like. In recent years, it has been further used as a communication medium for high-speed communication. Incidentally, in communication applications, generally, a plastic optical fiber cable (hereinafter simply referred to as an optical cable) in which various molten resins are coated on the outer periphery of a plastic optical fiber having a core-sheath structure or a core-sheath-protection layer structure. Is also used). As a coating material for such an optical cable, a nylon (polyamide) resin, a polyolefin resin such as polyethylene, a vinyl chloride resin, or the like is used.

[0003] In particular, nylon resins are solvent-resistant and are useful in an environment where machinery and control oils such as vehicles and machinery are used, but they have a complaint of insufficient flame retardancy. Polyolefin-based resins are inexpensive, but do not have sufficient flame retardancy like nylon resins. Although vinyl chloride resin is inexpensive and excellent in flame retardancy, it is necessary to add about 10 to 100 parts by weight of a plasticizer to 100 parts by weight of resin in order to enable melt molding. However, there is a problem that the plasticizer migrates to the plastic optical fiber and reduces the transmission loss and the mechanical strength of the plastic optical fiber. From these facts, at present, a plastic optical fiber cable suitable for use in communication, particularly for use in communication of vehicles and the like, has not yet been developed.

[0004]

SUMMARY OF THE INVENTION In addition, Japanese Patent Application Laid-Open No. Hei 3-10
No. 0610 discloses an optical cable in which the outer periphery of an optical fiber is coated with a flame-retardant resin such as chlorinated polyethylene having an oxygen index (OI) of 38 or more to improve flame retardancy. However, this optical cable had poor solvent resistance and could not be used in an environment using oil. The present invention has been made in view of the above circumstances, and is capable of preventing deterioration of a plastic optical fiber in an oil-existing environment such as a vehicle, which has solvent resistance, and has sufficient flame retardancy. The purpose is to provide a cable.

[0005]

According to the present invention, a primary coating layer made of a nylon resin having a melting point of 200 ° C. or less is provided on the outer circumference of a plastic optical fiber, and an oxygen index of 25 is provided on the outer circumference of the primary coating layer. A secondary coating layer made of the above resin is provided, and the thickness of the primary coating layer is 100 μm.
m or more, and the thickness (t ₂ ) of the secondary coating layer and the average outer diameter (d ₁ ) of the primary coating layer satisfy a relationship of 0.1 ≦ t ₂ / d ₁ ≦ 1.6. Can be solved by a plastic optical fiber cable. In particular, it is preferable that the plastic optical fiber is provided with a core material made of a polymer containing 70% by weight or more of a methyl methacrylate unit. For the secondary coating layer, one or a mixture of two or more selected from the group consisting of vinyl chloride resin, chlorinated polyethylene resin, nylon resin, polyethylene resin, polypropylene resin, urethane resin, and fluororesin is preferably used. .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the plastic optical fiber cable of the present invention, a primary coating layer and a secondary coating layer are formed on the outer periphery of the plastic optical fiber. The plastic optical fiber may have a two-layer structure in which a sheath made of a resin having a lower refractive index than the core is made around a core made of a transparent resin, or a protection made of a functional resin is further provided on the outer periphery of the sheath. 3 with layers
It may have a multilayer structure of more than two layers. Further, an optical fiber having a core portion in which a plurality of (co) polymers having different refractive indices are multilayered so that the refractive index gradually decreases from the center toward the outer peripheral portion, the refractive index from the center to the outer peripheral portion. It is also possible to use an optical fiber that gradually drops toward the bottom, or a sea-island type optical fiber in which a plurality of islands each having a core are integrated with each other while being separated from each other by a sea.

The core material is composed of a polymer containing at least 70% by weight of methyl methacrylate units, and polymethyl methacrylate and a copolymer thereof are preferably used. Examples of monomers that can be copolymerized with poly (methyl methacrylate) include, but are not limited to, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. When the content of the methyl methacrylate unit in the resin constituting the core material is less than 70%, light scattering is increased due to variation in the copolymer composition, and the transmission loss of the optical fiber tends to deteriorate. Examples of the resin constituting the sheath material include a copolymer containing polyvinylidene fluoride as a main component, a fluorinated methacrylate ester and its copolymer, a methacrylate ester polymer, a silicone resin, an α-fluoroacrylate resin, and polymethylpentene. And the like, but are not limited thereto. Examples of the resin constituting the protective layer include, for example, a copolymer containing vinylidene fluoride as a main component, a fluorinated methacrylate, an amorphous fluorine resin, a polycarbonate, a nylon resin, a polyester, a vinyl chloride resin, a vinylidene chloride resin, and a poly (vinylidene chloride) resin. Oxymethylene and the like are exemplified, and an appropriate resin is used depending on required properties such as heat resistance, solvent resistance, and flexibility.

[0008] The primary coating layer is composed of an oil-resistant resin, and a nylon resin is used. Oil-resistant resins other than nylon resins include fluororesins, polyoxymethylene resins, and ethylene-vinyl alcohol copolymer resins.These resins have a high coating temperature, and ethylene-vinyl alcohol copolymer resins absorb water. Occasionally a shape change occurs to cause an increase in transmission loss due to microbending in the plastic optical fiber, whereas nylon resin is preferable because it does not have these problems. In the present invention, the nylon resin constituting the primary coating layer has a melting point of 200 ° C.
It must be: If the melting point exceeds 200 ° C., it is necessary to heat the plastic optical fiber so that the resin temperature becomes 200 ° C. or higher when melt-coating the outer periphery of the plastic optical fiber. Transmission loss may increase. Examples of the nylon resin having a melting point of 200 ° C. or less include nylon 12, nylon 11, and nylon 12 elastomer. The nylon resin constituting the primary coating layer may contain a filler such as glass fiber or talc.

The secondary coating layer is composed of a resin having an oxygen index of 25 or more, and preferably a resin having an oxygen index of 27 or more, more preferably 30 or more. When the oxygen index of the secondary coating layer is less than 25, the flame retardancy of the optical cable is not sufficient, and when it is burned by a fire source such as a burner, it may spread. In the present invention, even when the resin constituting the core material and the primary coating layer is a polymethyl methacrylate and a nylon resin having a small oxygen index as described above, the oxygen index of the secondary coating layer is 25 or more. By doing so, sufficient flame retardancy as an optical cable can be obtained. As the secondary coating material having an oxygen index of 25 or more, a vinyl chloride resin, a chlorinated polyethylene resin, a fluororesin, or a nylon resin, a polyethylene resin, a polypropylene resin, or a urethane resin, which is obtained by adding a flame retardant to an oxygen index of 25 or more. Those made of a flammable resin are preferably used. These resins exert their functions sufficiently when used alone or as a mixture of two or more. As a flame retardant,
For example, halogen-based flame retardants such as tetrabromoethane, chlorinated paraffin, tetrabromobisphenol A, hexachlorobenzene, perchlorocyclopentadecane, triethyl phosphate, tributyl phosphate,
Phosphorus compounds such as bis (2,3 dibromopropyl) phosphate, metal hydroxides such as magnesium hydroxide, or antimony dioxide, talc and the like are preferable, and these are used alone or in combination of two or more. Can be

[0010] The plastic optical fiber cable of the present invention
, The thickness of the primary coating layer is 100 μm or more
It is necessary. If it is less than 100 μm, the engine
It is not possible to obtain sufficient durability in an environment where oil such as il exists.
For example, when used at high temperatures in the presence of oil, plastic
The shape change such as breakage or shrinkage of the optical fiber
You. The thickness of the primary coating layer is preferably 150 μm or more,
It is more preferably at least 200 μm. In addition, the present invention
And the average outer diameter of the primary coating layer (d₁) And the thickness of the secondary coating (t
_Two) Must satisfy the following equation. 0.1 ≦ t_Two/ D₁≦ 1.6 These ratios (t_Two/ D₁) Is less than 0.1, it is flammable
Optical fiber and primary coating made of different materials
Flame-retardant optical cables by applying a secondary coating to the layers
Optical fiber has low flame retardancy.
It becomes (T _Two/ D₁) Is preferably at least 0.2
More preferably, it is 0.25 or more. Also these
Ratio (t_Two/ D₁) Is larger than 1.6, outside the optical cable
The diameter becomes too large, and the flexibility is impaired.
Always difficult to handle. (T_Two/ D₁) Is preferably 1.2 or less
Lower, more preferably 1.0 or less. One more
At least one of the primary coating layer and the secondary coating layer is an optical cable.
To prevent the transmission of light from inside and outside the
Preferably, it is colored black. Primary
Coating layer and secondary coating layer can be colored as desired
May be.

The optical cable of the present invention is prepared by preparing a plastic optical fiber by a known method such as a melt spinning method, and forming a primary coating layer and a secondary coating on the periphery thereof by a method using, for example, a crosshead type extrusion coating apparatus. It can be manufactured by forming a layer. For example, 3 consisting of a core, a sheath, and a protective layer
When manufacturing an optical fiber having a layer structure by a melt spinning method,
Using a composite spinning nozzle in which a core resin outlet, a sheath resin outlet, and a protective layer resin outlet are arranged concentrically in order from the inside, the resin forming the core material, the sheath material, and the protective layer in this spinning nozzle Is supplied in a molten state, and a core material, a sheath material,
And the protective layer can be spun simultaneously to produce a plastic optical fiber. The primary coating layer and the secondary coating layer may be formed one by one sequentially using two crosshead type extrusion coating apparatuses, or the constituent resins of both layers may be formed using an apparatus capable of simultaneously forming both layers. It can also be extrusion coated at the same time.

[0012]

EXAMPLES Hereinafter, the effects of the present invention will be clarified by showing specific examples. In the following Examples and Comparative Examples, while actually producing a plastic optical fiber cable, the measurement of the oxygen index of the secondary coating material, the measurement of the transmission loss of the optical cable, the combustion test of the optical cable, and the solvent resistance test of the optical cable were performed. Each was evaluated by going. First, each evaluation method will be described. (1) Oxygen index measurement: It was measured by a test method according to JIS K7201. (2) Transmission loss measurement: The optical cable to be evaluated was dried at 50 ° C. for 48 hours to remove water absorbed in the plastic optical fiber, and then measured. For the measurement, white light was set to a wavelength of 650 nm using an interference filter, and the numerical aperture (NA) =
After narrowed by 0.1 lens, it enters the plastic optical fiber of the optical cable, to measure the amount of light emitted by the length 50 m (measured values and I _1). Next, the same optical cable was cut into a length of 25 m with the incident side fixed, and the amount of emitted light was measured (the measured value is I ₂ ). The transmission loss was calculated by the following equation. Incidentally, both ends of the plastic optical fiber were polished in advance. Transmission loss (dB / km) = 10 × log (I ₂ / I ₁ ) /
(0.05-0.025)

(3) Combustion test: A test was conducted by a cable combustion test method corresponding to UL1581 VW-1. The test was performed on 20 optical cables, and the number of passed optical cables was recorded. (4) Solvent resistance test: A plastic optical fiber cable to be evaluated was wound around a rod having a diameter of 100 mm, immersed in unleaded gasoline adjusted to a temperature of 50 ° C. for 500 hours, and then cooled for 25 hours.
After storage in a temperature controlled room at 24 ° C. for 24 hours, the optical cable (reference numeral 1 in the figure) was sandwiched between rods (diameter 2 in the figure) having a diameter of 30 mm and bent 90 ° to the left and right as shown in FIG. Before bending, and each time bending was performed once on each of the left and right sides, light from a light source (reference numeral 3 in the drawing) was made to enter the optical cable 1 and the amount of emitted light was measured. The number of bends (one time for each of the right and left sides) until the amount of light became half of the initial output light amount before bending was recorded. The greater the solvent deterioration of the plastic optical fiber, the smaller the number of times of bending, so that the solvent resistance of the optical cable can be evaluated.

Example 1 Preparation of core resin: 100 parts by weight of methyl methacrylate
0.19 parts by weight of n-butyl mercaptan and 0.0018 parts by weight of di-tert-butyl peroxide were uniformly mixed, and the dissolved oxygen was replaced with nitrogen. % Of a monomer-polymer mixture, and then continuously supplied to a vented devolatilizing extruder to remove volatile components such as monomers, and quantitatively fed by a core material spinning gear pump. It was supplied to the core material inlet of the sheath composite spinning nozzle. Preparation of sheath material resin: 3FM (2,2,2-trifluoroethyl methacrylate) / 17FM (1,1,2,2-
Tetrahydroperfluorodecyl methacrylate) / M
A copolymer obtained from a monomer composition having a ratio of MA (methyl methacrylate) / MAA (methyl acrylate) of 45/40/14/1 (% by weight) is supplied to an extruder and melted. The mixture was fed through a spinning gear pump to the sheath material inlet of a core / sheath composite spinning nozzle set at 220 ° C. Production of plastic optical fiber: core material and sheath material are simultaneously discharged from the core / sheath composite spinning nozzle, spun, cooled, taken up at a speed of 10 m / min, and further heated at 140 ° C.
After stretching twice in a stretching machine at a temperature of, and measuring the in-line transmission loss, the average diameter is 1000 µm and the sheath thickness is 10 µm
The plastic optical fiber was wound up. The transmission loss of the obtained plastic optical fiber is 1 at a wavelength of 650 nm.
It was 28 dB / km.

Primary Coating: Nylon 12 (manufactured by Daicel Huls Co .; Diamid L-1640B, melting point: 178 ° C.) is coated on the outer periphery of the plastic optical fiber obtained above using a crosshead type extrusion coating apparatus. A primary coating layer was formed. The crosshead die temperature was 205 ° C. The average outer diameter of the primary coating layer was 1400 μm, and the thickness was 200 μm. Secondary coating: Using a crosshead extrusion coating device,
The outer periphery of the primary coating layer formed above was coated with a vinyl chloride resin to form a secondary coating layer to obtain an optical cable. The vinyl chloride resin used contained 20 parts by weight of TOTM (tri-2-ethylhexyl trimellitate) as a plasticizer, and had an oxygen index of 32. The crosshead die temperature was 160 ° C. The average outer diameter of the secondary coating layer is 22
It was 00 μm. The thickness t _{2 of the} secondary coating of the obtained optical cable is 400 μm, and the average outer diameter d ₁ of the primary coating layer is 140 μm.
0 μm, the value of these ratios t ₂ / d ₁ is 0.28
It was 6. The transmission loss of the obtained optical cable is 13
It was as good as 2 dB / km, and in the combustion test, 18 out of 20 passed and were good. The results of the solvent resistance and the comprehensive evaluation are as shown in Table 2. Regarding the comprehensive evaluation, those having no particular problems were marked with "O", and those having problems were described with their problems.

(Examples 2 to 9, Comparative Examples 1 to 5) Material of primary coating layer, thickness of primary coating layer, average outer diameter d of primary coating layer
₁ , primary coating temperature (ie crosshead die temperature),
The conditions such as the material of the secondary coating layer, the thickness t _{2 of the} secondary coating layer, the average outer diameter of the secondary coating layer, and the secondary coating processing temperature (that is, the crosshead die temperature) were changed as shown in Table 1 below. An optical cable was manufactured in the same manner as in Example 1 above. Evaluation was performed in the same manner as in Example 1. Table 1 also shows the melting point of the primary coating material, the oxygen index of the secondary coating material, and the value of t ₂ / d ₁ . In addition, the measurement results of optical cable transmission loss,
Table 2 shows the results of the combustion test, the results of the solvent resistance evaluation, and the overall evaluation.

Example 10 An optical cable was manufactured and evaluated in the same manner as in Example 1 except that the following points were changed. The main parameters and the results of each evaluation are shown in Tables 1 and 2 below. Changes: The composition of the core resin was changed to methyl methacrylate 9
0 parts by weight, methyl acrylate 10 parts by weight, n-butyl mercaptan 0.22 parts by weight, and azooctane (trade name: VR-110, manufactured by Wako Pure Chemical Industries, Ltd.) 0.0035 parts by weight. Further, the temperature of the polymerization vessel was set to 130 ° C, and the weight ratio was set to 4 ° C.
3%. In the above, the composition of the sheath resin was changed to 5FM (2, 2, 3,
3,3-pentafluoropropyl methacrylate) / 1
7FM / MMA / MAA ratio of 30/50/18/2
(% By weight).・ The take-up speed was 20 m / min, the average diameter of the plastic optical fiber was 750 μm, and the sheath thickness was 8 μm.
m. The transmission loss of the obtained plastic optical fiber was 137 dB / km. (1) In (1) and (2), a primary coating layer and a secondary coating layer were simultaneously formed using a crosshead type extrusion coating apparatus capable of simultaneously extrusion coating two layers. The constituent resin of the secondary coating layer was changed to chlorinated polyethylene (critical oxygen index: 38), and the crosshead die temperature was 205 ° C. The average outer diameter of the primary coating layer was measured after stopping the supply of the secondary coating material.
It was 150 μm.

Example 11 and Comparative Example 6 Example 10 above
In Table 1, an optical cable was manufactured by changing the thickness of the primary coating layer and / or the thickness of the secondary coating layer as shown in Table 1, and was evaluated. Table 2 shows the evaluation results.

Example 12 An optical cable was manufactured and evaluated in the same manner as in Example 1 except that the following points were changed. The main parameters and the results of each evaluation are shown in Tables 1 and 2 below. Changes: The composition of the core resin was changed to methyl methacrylate 8
0 parts by weight, 20 parts by weight of ethyl acrylate, 0.2 parts by weight of n-butyl mercaptan, and 0.0018 parts by weight of dibutyl butyl peroxide. The temperature of the polymerization vessel was set to 130 ° C., and the weight ratio was set to 45%. In the composition of the sheath resin, 5FM / 17FM / M
The MA / MAA ratio was 30/50/18/2 (% by weight). The core / sheath / protection layer composite spinning nozzle was used in and. -As 'new', a copolymer obtained from a composition having a vinylidene fluoride / tetrafluoroethylene ratio of 80/20 (mol%) was supplied to an extruder and melted, and then passed through a protective material spinning gear pump. Core / sheath set at 220 ° C
The protective layer was fed to the protective layer material inlet of the composite spinning nozzle.・ In the core material from the core / sheath / protection layer composite spinning nozzle,
The sheath material and the protective layer material were simultaneously discharged and spun. The take-up speed was 42 m / min, the stretching machine temperature was 150 ° C., the stretching ratio was 2.2 times, and the average diameter of the plastic optical fiber was 5
00 μm and a sheath thickness of 6 μm. The transmission loss of the obtained plastic optical fiber was 146 dB / km. (1) In (1) and (2), a primary coating layer and a secondary coating layer were simultaneously formed using a crosshead type extrusion coating apparatus capable of simultaneously extrusion coating two layers. Crosshead die temperature is 2
05 ° C. The average outer diameter of the primary coating layer was 900 μm when measured while the supply of the secondary coating material was stopped.

Comparative Examples 7 and 8 In Example 12, as shown in Table 1, the primary coating material, the primary coating layer thickness,
An optical cable was manufactured by changing the thickness of the secondary coating layer and / or was evaluated. Table 2 shows the evaluation results.

[0021]

[Table 1]

[Table 2]

In Table 1, POF means plastic optical fiber. Further, 1) to 7) represent the following materials, respectively. 1) Nylon 11: Rilsan BECNO TL (manufactured by Toray Industries, Inc.) 2) Nylon elastomer: DAIAMID-PAE E4
0 (manufactured by Daicel Huls) 3) Nylon 66: Amilan CM3007 (manufactured by Toray Industries) 4) Chlorinated PE (polyethylene): Eraslen 303C
(Showa Denko KK) 5) Flame retardant urethane: Elastollan VP1185A10F
(Takeda Birdish Urethane Industry Co., Ltd.) 6) ETFE (ethylene / tetrafluoroethylene copolymer): NEOFLON ETFE (Daikin Industry Co., Ltd.) 7) Flame retardant PE (polyethylene): low density polyethylene 1
Chlorinated paraffin / antimony oxide / magnesium hydroxide = 10/6/30 parts by weight based on 00 parts by weight

From the above Tables 1 and 2, Examples 1 to 12
In both cases, good results have been obtained,
In Comparative Examples 1, 6, and 7 in which the value of t ₂ / d ₁ was smaller than 0.1, the flame retardancy was poor, and in Comparative Example 4 in which the value of t ₂ / d ₁ was larger than 1.6, the handleability was poor. In Comparative Examples 2 and 8 in which the melting point of the primary coating layer was higher than 200 ° C., the transmission loss of the optical cable was large because the primary coating processing temperature was high. In Comparative Example 3 in which the oxygen index of the secondary coating layer was smaller than 25, none of the samples passed the combustion test. The thickness of the primary coating layer is 100μ
In Comparative Example 5 smaller than m, the solvent resistance was poor.

[0024]

As described above, according to the present invention, a plastic optical fiber cable having a small optical transmission loss, excellent flame retardancy and solvent resistance, sufficient flexibility and easy handling can be obtained. Can be This plastic optical fiber cable does not cause deterioration of the plastic optical fiber in an oil-existing environment such as a vehicle and has sufficient flame retardancy, and is suitably used for in-vehicle communication such as a vehicle and a railway. be able to. In particular, if the plastic optical fiber has a core material made of a polymer containing 70% by weight or more of a methyl methacrylate unit, transmission loss is small and long-distance transmission is possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a bending test evaluation method according to an example of the present invention.

[Explanation of symbols]

 1. Optical cable, 2. Rod, 3. Light source

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yoshihiro Uozu 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory F-term (reference) 2H050 AB43X AB44Y AB46Y AB47Y AB50X BA02 BA34 BB03R BB03S BB08Q BB08S BB09Q BB09S BB13Q BB15Q BD03

Claims (3)

[Claims] A primary coating layer made of a nylon resin having a melting point of 200 ° C. or less is provided on an outer periphery of a plastic optical fiber, and a secondary coating made of a resin having an oxygen index of 25 or more is provided on the outer periphery of the primary coating layer. And the thickness of the primary coating layer is 100 μm or more, and the thickness (t ₂ ) of the secondary coating layer and the average outer diameter (d ₁ ) of the primary coating layer are 0.
A plastic optical fiber cable which satisfies a relationship of 1 ≦ t ₂ / d ₁ ≦ 1.6. 2. The plastic optical fiber cable according to claim 1, wherein the plastic optical fiber has a core material made of a polymer containing at least 70% by weight of methyl methacrylate units. 3. The secondary coating layer is one or a mixture of two or more selected from the group consisting of vinyl chloride resin, chlorinated polyethylene resin, nylon resin, polyethylene resin, polypropylene resin, urethane resin, and fluororesin. The plastic optical fiber cable according to claim 1, wherein the cable comprises: