JP2004053707A - Plastic optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute a covering layer whose strength is not lowered even under a high-temperature and high-humidity condition, and which is excellent in flame retardance, abrasion resistance and flexibility in a plastic optical fiber cable. <P>SOLUTION: The cable is constituted by coating a bare plastic optical fiber with a coating resin composition constituted by kneading a polyolefin resin compound obtained by dispersing and kneading magnesium hydroxide in a polyolefin resin, a polyamide resin and a maleinated polymer. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a flexible plastic optical fiber cable suitable for use in an automobile or a factory.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an in-vehicle plastic optical fiber cable (hereinafter, referred to as “cable”) used in an automobile, a core is made of polymethyl methacrylate (PMMA) resin, and a sheath layer surrounding the core is made of fluororesin. There has been proposed a configuration in which nylon 12 is coated on the outside of the bare plastic optical fiber thus formed, and then a resin called soft nylon having low hardness, such as polyetheramide or polyetheresteramide, is coated on the outer layer.
[0003]
[Problems to be solved by the invention]
However, as a result of an examination by the present inventor of the above-mentioned cable, the above-mentioned resin called soft nylon shows that the resin required for a long-term exposure under the high temperature and high humidity conditions of 85 ° C. and 85% relative humidity, which are the required characteristics of an in-vehicle cable. It has been found that a problem of strength reduction due to hydrolysis occurs.
[0004]
The present inventor has found that the above problem can be solved by using a nylon 6-12 copolymer for the outer layer coating instead of the soft nylon. However, although the above nylon 6-12 copolymer has a lower hardness than nylon 12 used as an inner layer coating, it has insufficient flexibility in handling when assembling a cable into a wire harness. .
[0005]
Examples of the material for the outer layer coating include vinyl chloride resin and polyolefin resin in addition to nylon. However, vinyl chloride resins are not welcome from an environmental standpoint. In addition, polyolefin resin has strong flammability, and from the viewpoint of environmental pollution, in order to add flame retardant that does not contain chlorine or bromine to impart flame resistance, a large amount of metal hydroxide such as magnesium hydroxide must be used. It has to be used, and when a large amount of metal hydroxide is added to the polyolefin resin, there is a problem that the wear resistance and the mechanical strength are reduced.
[0006]
An object of the present invention is to provide a cable having characteristics that can withstand use in a severe environment such as in an automobile. Specifically, the cable has a strength even when exposed to high temperature and high humidity for a long time. An object of the present invention is to provide a plastic optical fiber cable, which comprises a coating material which does not decrease, has flame resistance and abrasion resistance and has sufficient flexibility.
[0007]
[Means for Solving the Problems]
The present invention is a plastic optical fiber cable characterized in that it is coated with a coating resin composition containing at least a polyamide resin, a maleated polymer, a polyolefin resin and magnesium hydroxide.
[0008]
In a preferred embodiment, the cable of the present invention is such that the coating resin composition is obtained by kneading a polyolefin resin compound in which magnesium hydroxide is dispersed and kneaded in advance with a polyolefin resin, a polyamide resin, and a maleated polymer. Including.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The cable of the present invention is a plastic optical fiber cable that withstands use under severe environments such as in automobiles, and has excellent flexibility, heat resistance, chemical resistance, moisture and heat resistance, flame retardancy, and abrasion resistance. Cables with excellent overall characteristics are completely new.
[0010]
The cable of the present invention achieves the above characteristics by using a specific coating resin composition comprising at least a polyamide resin, a maleated polymer, a polyolefin resin, and magnesium hydroxide for the outer layer coating. This will be described in detail below.
[0011]
The polyolefin resin is excellent in chemical resistance, and has a lower flexural modulus than the polyamide resin. By blending the polyolefin resin with the polyamide resin, flexibility can be obtained. However, the polyolefin resin has high flammability as described above, and in the present invention, the cable is provided with flame retardancy by adding magnesium hydroxide as a flame retardant to the polyolefin resin.
[0012]
In general, the flame retardant effect cannot be obtained unless magnesium hydroxide is added to the polyolefin resin in a large amount of 40 to 70% by weight. However, the polyolefin resin compound to which the magnesium hydroxide is added in such a large amount has a low abrasion resistance. It will be inferior.
[0013]
In the present invention, by kneading the polyolefin resin with the polyamide resin, the wear resistance is remarkably improved. It is considered that the reason is that the coating resin composition of the present invention containing a polyolefin resin and a polyamide resin as components has a structure in which a polyamide resin having excellent wear resistance surrounds the polyolefin resin. . That is, it is considered that a particularly preferred microstructure of the coating resin composition is a sea-island alloy having a sea of polyamide resin and islands of polyolefin resin.
[0014]
In order to secure the flame retardancy of the coating resin composition, it is particularly preferable that the above-mentioned polyolefin resin component and polyamide resin component constituting the coating resin composition have flame retardancy independently. Therefore, magnesium hydroxide needs to be mainly dispersed in the polyolefin resin. However, when magnesium hydroxide is blended in the presence of the polyamide resin and the polyolefin resin, the magnesium hydroxide is easily dispersed in the polyamide resin. Therefore, before kneading the polyolefin resin with the polyamide resin, it is desirable to disperse magnesium hydroxide in the polyolefin resin in advance to adjust the polyolefin resin compound, and to knead the polyolefin resin compound with the polyamide resin.
[0015]
A polyolefin resin compound containing a large amount of magnesium hydroxide has a low fluidity at the time of melting, and when kneaded with a polyamide resin, the polyamide resin tends to become a sea component and the polyolefin resin compound tends to become an island component. As described above, the polyamide resin is excellent in abrasion resistance, and the sea-island structure reflects the abrasion resistance of the polyamide resin in the coating resin composition. Therefore, the tendency is more effective in the present invention.
[0016]
In the present invention, magnesium hydroxide is an essential component, and is preferably contained in the polyolefin resin compound in an amount of 40 to 70% by weight, more preferably 50 to 70% by weight. As an auxiliary flame retardant, it is also possible to add another metal hydroxide compound or a phosphorus compound as appropriate, so that the oxygen index of the polyolefin resin compound is preferably 30 or more, more preferably 35 or more. Add flame retardant.
[0017]
On the other hand, the polyamide resin is also preferably used as a polyamide resin compound to which a flame retardant has been added. Before kneading with the polyolefin resin compound, it is preferable to knead the polyamide resin with melamine cyanurate as a flame retardant in advance. When melamine cyanurate is added, it is preferably added in an amount of 1 to 20% by weight, more preferably 5 to 15% by weight, based on the polyamide resin.
[0018]
As the polyamide resin used in the present invention, nylon 6-12, nylon 6-11, etc. are preferably used in addition to nylon 12, nylon 11, nylon 6, and the like. Among them, nylon 6-12 having a low flexural modulus is particularly preferable. These resins may be used alone or in combination of two or more. Incidentally, even in the case of the polyamide resin, polyetheramide or polyetheresteramide called soft nylon described above has a low flexural modulus, but is deteriorated by hydrolysis under high-temperature and high-humidity conditions, and is not preferable as in the above specific examples. .
[0019]
Examples of the polyolefin resin used in the present invention include a polyolefin elastomer resin, a polypropylene resin, a polyethylene resin, an ethylene-ethyl acrylate copolymer, an ethylene-vinyl acetate copolymer, an ethylene-α-olefin copolymer, and a polymerization type TPO type polypropylene. Resins, propylene-α olefin copolymers, ethylene-α olefin copolymers and the like. These polyolefin resins may be used alone or as a mixture of two or more. Further, in addition to one or more of these polyolefin resins, an elastomer other than the polyolefin resin may be contained.
[0020]
Since the polyolefin resin component used in the present invention is a component for imparting flexibility, its flexural modulus is preferably 50 to 1000 MPa lower than that of the polyamide resin, and particularly preferably 200 to 600 MPa. preferable.
[0021]
By the way, since the dispersion between the resins by kneading the polyamide resin and the polyolefin resin is unstable, a compatibilizer is required. In the present invention, a maleated polymer is used as a compatibilizer. As the maleated polymer used in the present invention, for example, a maleated polyolefin resin or a maleated hydrogenated diene resin is preferably used.
[0022]
The maleated polyolefin resin can be selected from a polypropylene-based resin, a polyethylene-based resin, and an ethylene / propylene copolymer-based resin. These maleated polyolefin resins are sold, for example, by Mitsui Chemicals, Inc. under the trade name “Admer”.
[0023]
Examples of the maleated hydrogenated diene-based resin include a maleated hydrogenated conjugated diene polymer, a maleated hydrogenated aromatic vinyl / conjugated diene block, and a random copolymer. Butadiene and isoprene include styrene and α-methylstyrene as aromatic vinyl. For example, the resin can be selected from resins sold by Asahi Kasei Corporation under the trade name “ToughTech M Series”.
[0024]
In the present invention, a preferable mixing ratio of the polyamide resin, the polyolefin resin compound, and the maleated polymer is as follows: P / A is 2/8 to 8/2, where A, P, and M are mixed parts by weight, respectively. (A + P) is 2/95 to 50/50. In addition, P indicates a mixed part by weight of a polyolefin resin compound in which magnesium hydroxide is added to a polyolefin resin, and when a flame retardant is dispersed in a polyamide resin, the above A is a polyamide resin compound containing a flame retardant. Means mixed parts by weight.
[0025]
As a preferred embodiment of the cable of the present invention, it is possible to adopt a configuration in which a coating layer made of the above-mentioned coating resin composition according to the present invention is provided on a bare plastic optical fiber consisting of a core and a sheath layer. . Further, the present invention relates to an inner coating layer comprising a polyamide resin, a polyolefin resin, a polyolefin elastomer resin, a polyvinyl chloride resin, a vinylidene fluoride resin, a polyurethane resin, a polyester elastomer resin, etc., which have been conventionally used as a coating material. And a cable having a multilayer coating structure having an outer coating layer made of the coating resin composition according to the above. FIG. 1 shows a schematic cross-sectional view of an example of the cable having the multilayer coating structure. In the figure, 1 is a core, 2 is a sheath layer, 3 is a bare plastic optical fiber, 4 is an inner coating layer, and 5 is an outer coating layer.
[0026]
Above all, a preferred form as a cable for a vehicle is a plastic optical fiber bare wire coated with a strong polyamide resin having a tensile modulus and a flexural modulus of 1000 to 1500 MPa such as nylon 12 and an outer layer having a flexural modulus of elasticity. The outer layer is coated with the coating resin composition according to the present invention, which has a lower value, and the cable is flexibly configured. In particular, by disposing an inner coating layer made of a polyamide resin inside the outer coating layer made of the coating resin composition according to the present invention, the bare plastic optical fiber and the inner coating layer can be integrally attached to the connector. Is preferable.
[0027]
The bare plastic optical fiber used in the present invention comprises a core and a sheath layer surrounding the core, and the core resin constituting the core comprises a transparent resin such as polymethyl methacrylate (PMMA) resin or polycarbonate resin, and constitutes the sheath layer. Preferably, the sheath resin is made of a fluororesin having a lower refractive index than the resin constituting the core. Further, the sheath layer may have a single layer structure or a multilayer structure of two or more layers.
[0028]
The cable of the present invention and the diameter of the bare wire constituting the cable are as follows: the diameter of the core of the bare wire is about 0.9 to 1.0 mm; the outer diameter of the bare wire is about 0.95 to 1.1 mm; It is preferably applied to those having a diameter of about 1.2 to 4.0 mm. In a conventional vehicle cable, the outer diameter of the bare wire is 1.0 mm, the outer diameter of the inner coating layer is 1.5 mm, and the outer diameter of the outer coating layer is 2.3 mm.
[0029]
【Example】
A PMMA resin having a refractive index of 1.492 at 23 ° C. at a sodium D line was used as a core resin, a fluorinated methacrylate resin having a refractive index of 1.410 was used as a sheath resin of the first layer (inside), and vinylidene fluoride 40 was used. A copolymer composed of mol%, 48 mol% of tetrafluoroethylene and 12 mol% of hexafluoropropene and having a refractive index of 1.36 and a melting point of 155 ° C. was used as a sheath resin for the second layer (outside). By composite spinning, a plastic optical fiber bare wire having a core diameter of 0.96 mm, an outer diameter of the first sheath layer of 0.98 mm, and an outer diameter of the second sheath layer of 1.0 mm was obtained.
[0030]
The obtained bare wire was coated with black nylon 12 so as to have an outer diameter of 1.5 mm to form an inner coating layer. Further, 50 parts by weight of a resin containing 10% by weight of melamine cyanurate in a nylon 6-12 copolymer having a flexural modulus of 800 MPa (defined by ISO 178), and maleated hydrogenated aromatic vinyl / conjugated A coating resin composition was prepared by kneading 10 parts by weight of a diene block copolymer ("ToughTech M1943" manufactured by Asahi Kasei Corporation) and 40 parts by weight of flame-retardant polyethylene as a polyolefin resin compound using a twin-screw extruder. An outer layer was coated on the outer side of the inner layer so as to have an outer diameter of 2.3 mm to obtain a cable. The flame-retardant polyethylene was a compound comprising 40 parts by weight of a polyethylene-1 butene copolymer and 60 parts by weight of magnesium hydroxide, had an oxygen index of 34, and had a flexural modulus of the coated resin composition of 560 MPa.
[0031]
In order to evaluate the ease of bending of the obtained cable, the bending strength of the cable was measured. The measuring method is as follows. A cable having a length of 10 cm is laid at a temperature of 23 ° C. with a distance of 15 mm between the chucks, the cable at the center between the chucks is pressed with a spatula at a pressing speed of 50 mm / min, and the initial cable deflection (mm ) Was used to determine the bending strength. As a result, the bending strength of the cable of this example was 9 N / mm. This was much more flexible than the 15 N / mm of the conventionally used in-vehicle plastic optical fiber cable.
[0032]
Next, the flame resistance of the cable of this example was evaluated by a combustion test. The combustion test was performed by wrapping a cable around a copper wire inclined at 45 ° C. and irradiating a burner flame for 10 seconds. As a result, the flame went out between 15 and 20 seconds. This satisfies the flame-retardant condition of 30 seconds or less for self-extinguishing property, which is a specification for a vehicle-mounted cable.
[0033]
Next, a wear test of the plastic optical fiber cable of this example was performed. The test was carried out according to the following method according to DIN72551. A horizontal groove is cut at the tip of the spatula that repeatedly wears, and the upper half of a stainless steel wire having a diameter of 0.256 mm is fixed so that it protrudes. A 7N load is applied to the spatula, and the plastic optical fiber is cycled at 55 rpm. A 15 mm reciprocating motion was performed 500 times on the cable. As a result, the outer coating layer was worn as shown in the schematic cross-sectional view of FIG. 2, and the wear thickness (t) was 290 μm. However, the outer coating layer did not reach the inner coating layer. It turned out to withstand use. In FIG. 2, 2a is a first sheath layer, 2b is a second sheath layer, and the same members as those in FIG.
[0034]
Furthermore, the moisture and heat resistance of the cable of this example was evaluated. The evaluation method was as follows. After leaving the plastic optical fiber cable in an environment of a temperature of 85 ° C. and a relative humidity of 85% for 3000 hours, the transmission loss was measured with monochromatic light of 650 nm at an incident NA of 0.6. As a result, the transmission loss was stable at 200 dB / km. In addition, the elongation at break of the cable was 90%, which was sufficient performance.
[0035]
【The invention's effect】
As described above, according to the present invention, it exhibits a long-term stable strength even in a high-temperature and high-humidity environment, has excellent flame retardancy and abrasion resistance, and is easy to handle even when assembled into a wire harness. A plastic optical fiber cable is provided that exhibits improved flexibility.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of one embodiment of a plastic optical fiber cable of the present invention.
FIG. 2 is a schematic cross-sectional view of a plastic optical fiber cable after a wear resistance test in an example of the present invention.
[Explanation of symbols]
Reference Signs List 1 core 2 sheath layer 2a first sheath layer 2b second sheath layer 3 plastic optical fiber bare wire 4 inner coating layer 5 outer coating layer

Claims (2)

A plastic optical fiber cable which is coated with a coating resin composition containing at least a polyamide resin, a maleated polymer, a polyolefin resin and magnesium hydroxide. The plastic optical fiber cable according to claim 1, wherein the coating resin composition is obtained by kneading a polyolefin resin compound in which magnesium hydroxide is dispersed and kneaded in a polyolefin resin in advance, a polyamide resin, and a maleated polymer.

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