JPH10307218A - Plastic optical fiber and plastic optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plastic optical fiber which is usable for a long time in the high-temp. environment and is free from noises from outside by providing the outer side of a sheath layer with a light shielding layer consisting of a specific resin compsn. SOLUTION: A core 1 consists of a polymethyl methacrylate(PMMA) resin. The sheath layer 2 is formed of a transparent fluororesin having the refractive index lower than the refractive index of the PMMA resin used for the core 1. The light shielding layer 3 is formed by tightly coating the sheath layer 2 with a coating resin compsn. prepd. by adding carbon black to a vinylidene fluoride based resin having >=50 wt.% vinylidene fluoride structural unit in such a manner that the thickness attains 3 to 300 μm. While the carbon black may be incorporated into the coating resin compsn. up to about 10 wt.% the content thereof is preferably <=7 wt.% in order to smoothly execute the coating to the sheath layer 2. Further, the sheath layer is provided with an external coating layer 5 consisting of a thermoplastic resin in order to impart mechanical strength, chemical resistance, fashion characteristic, identifiability, etc., to the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an automobile, an aircraft,
Moving objects such as ships, factory automation,
The present invention relates to a plastic optical fiber and a cable used for short-distance optical communication such as office equipment and multimedia.

[0002]

2. Description of the Related Art Plastic optical fibers are more flexible than quartz-based fibers, and have a large diameter and a high numerical aperture. Applications to fields such as sensors and sensors have begun.

Conventionally, plastic optical fibers that have been put into practical use use a resin (PMMA resin) or a polycarbonate resin mainly composed of methyl methacrylate as a core material and a vinylidene fluoride copolymer or a fluoride resin as a sheath material. Some use methacrylate-based copolymers. It is also used as a plastic optical fiber cable in which a sheath layer is coated with low-density polyethylene or polyvinyl chloride.

In an optical fiber cable, the incidence of light from the outside becomes noise and adversely affects signal transmission. As a means for preventing this noise, a plastic optical cable provided with a light-impermeable layer outside a sheath layer is used. A fiber cable is disclosed in JP-A-3-100608.

[0005]

However, the above-mentioned light impermeable layer is formed of a resin having an extrusion temperature of 170 ° C. or lower, for example, polyethylene or polyvinyl chloride. The light-impermeable layer formed of such a resin does not adhere to the sheath layer and can be mechanically peeled off. In such a coating form, the sheath layer and the light-impermeable layer Have individual thermal shrinkage behavior and are inferior in heat resistance. Therefore,
In applications where high heat resistance is required, such as automobiles, applicable places are limited.

An object of the present invention is to solve the above-mentioned problems and to provide a plastic optical fiber wire and a cable which can be used for a long time in a high temperature environment and have no problem of external noise. More specifically, an object of the present invention is to provide a plastic optical fiber wire and cable having high heat resistance and light shielding ability.

[0007]

Means for Solving the Problems A first aspect of the present invention is to provide a core made of a polymethyl methacrylate resin, a sheath layer surrounding the core and made of a transparent fluororesin having a lower refractive index than the core, and a vinylidene layer. 50% by weight of fluoride structural unit
A light shielding layer comprising a coating resin composition obtained by adding carbon black to a vinylidene fluoride-based resin containing the above, and being closely coated with a thickness of 3 μm to 300 μm on the outside of the sheath layer. This is a plastic optical fiber.

A second aspect of the present invention is a plastic optical fiber cable characterized in that an outer coating layer made of a thermoplastic resin is further provided outside the above-mentioned plastic optical fiber strand. As the resin, a polyamide resin is preferably used.

In the plastic optical fiber of the present invention, by providing a light shielding layer made of a specific resin composition on the outside of the sheath layer, sufficient light shielding ability and high heat resistance can be obtained at the same time. Can be used. In addition, the plastic optical fiber cable of the present invention using the plastic optical fiber of the present invention has a sufficient light shielding ability, so that the outer coating layer can be colored in a desired color. In particular, when the outer coating layer is made of polyamide resin, a cable that can withstand both high and low temperature environments and has excellent mechanical strength and chemical resistance can be obtained. can get.

[0010]

FIG. 1 schematically shows a cross section of a plastic optical fiber cable according to the present invention. In the figure, 1 is a core,
Reference numeral 2 denotes a sheath layer, and 3 denotes a light shielding layer. A plastic optical fiber cable 6 of the present invention is further provided with an outer coating layer 5 on the outside of the optical plastic optical fiber strand 4 of the present invention composed of these 1-3. is there.

In the present invention, the core 1 is made of a PMMA resin. The PMMA resin is a transparent polymer containing 80% by weight or more of methyl methacrylate as a monomer component. In addition to a homopolymer of methyl methacrylate, an acrylic ester, a methacrylic ester, acrylic acid, methacrylic acid, A copolymer of one or more components such as maleimide and methyl methacrylate can be used. As the PMMA resin used in the present invention, those having a melt flow index in the range of 0.1 to 45 g / 10 minutes under the conditions of 230 ° C., load 3.8 kg, orifice diameter 2 mm and length 8 mm are preferably used. can do.

In the present invention, the sheath layer 2 is made of P
It is formed of a transparent fluororesin having a lower refractive index than the MMA resin. Specifically, a polymer comprising at least one of fluoroalkyl methacrylate, fluoroalkyl acrylate or α-fluoro-fluoroalkyl acrylate in which the α-position is substituted with fluorine, or a vinylidene fluoride-based transparent resin such as vinylidene fluoride A copolymer of a sulfide and hexafluoroacetone, or a terpolymer or a terpolymer obtained by further adding trifluoroethylene or tetrafluoroethylene to these binary components, and a copolymer of vinylidene fluoride and hexafluoropropene; Alternatively, a terpolymer or terpolymer obtained by further adding trifluoroethylene or tetrafluoroethylene to these binary components, a binary copolymer of vinylidene fluoride and tetrafluoroethylene, or a copolymer of vinylidene fluoride and trifluoroethylene. And the like.

In addition to the above, a mixture of the above-mentioned vinylidene fluoride resin and PMMA or polyethyl methacrylate is used, and those having a melt flow index of about 1 to 200 g / 10 minutes under the above conditions are preferably used.

In the present invention, the light shielding layer 3 is made of a coating resin composition obtained by adding carbon black to a vinylidene fluoride resin containing at least 50% by weight of a vinylidene fluoride structural unit so as to have a thickness of 3 to 300 μm. And the sheath layer 2.

In the light shielding layer 3 according to the present invention, the ratio C [% by weight] of the carbon black in the coating resin composition.
And the product of the thickness D [μm] of the light shielding layer 5 is 100% by weight.
.Mu.m] or more, the effect of noise can be prevented even when the 50 m long strand 4 is exposed to direct sunlight. Also,
If the above product is 20 [wt% · μm] or more, the light shielding layer 3
The optical power that enters the inside of the device through can be made smaller than -40 dBm. Depending on the light noise environment,
In some cases, such as lightning bolts, which are extremely intense, or in a light disturbance environment that is weaker than direct sunlight, the C × D value is usually 5% by weight.
.Mu.m] or more, more preferably 2
0% by weight or more, preferably 100% by weight
μm] or more.

The carbon black can be contained in the coating resin composition up to about 10% by weight, but is preferably not more than 7% by weight, more preferably 5% by weight, in order to smoothly coat the sheath layer. It is as follows.

In the strand of the present invention, for the purpose of handling the strand as a bare wire, for example, when fixing the terminal of the strand to the connector, the outer diameter of the ferrule of the connector is usually small. It is preferable that the thickness of the light shielding layer 3 is not too large. Assuming a bare wire having a diameter of about 0.5 to 1.5 mm, the thickness of the light shielding layer 3 is 3 to 300 μm.
m. The most preferable thickness is 10 μm or more at which the heat resistance imparted by the light shielding layer 3 becomes effective, and the upper limit is preferably about 200 μm for the purpose of making the element wire capable of being handled like a bare wire.

The vinylidene fluoride resin used in the light shielding layer 4 according to the present invention is a resin containing at least 50% by weight of a vinylidene fluoride structural unit, and specifically, a homopolymer of vinylidene fluoride, In addition to the copolymer of vinylidene fluoride and chlorotrifluoroethylene, the above-mentioned vinylidene fluoride resin conventionally used as a sheath material of a plastic optical fiber, for example, a copolymer of vinylidene fluoride and tetrafluoroethylene Polymers, copolymers of vinylidene fluoride and hexafluoropropene, and copolymers of vinylidene fluoride, tetrafluoroethylene and hexafluoropropene. When the resin having a vinylidene fluoride structural unit of 50% by weight or more is coated with a fiber having a sheath layer made of a fluororesin as described above, the resin is well adhered and integrated with the sheath layer, and peeled off with a wire stripper or the like. It is characterized in that it does not shift, and the connector is not peeled off when the light shielding layer is fixed. In addition, the resin can impart chemical resistance and heat resistance to the plastic optical fiber.

The coating resin composition used in the present invention may optionally contain a trace amount of additives such as wax.

In the plastic optical fiber of the present invention, the following two methods are preferably used as a method for coating the light shielding layer around the sheath layer.

The first method is a method of spinning a fiber comprising a core and a sheath layer, and then coating the fiber with a coating resin composition melted by a crosshead die so as to coat the electric wire. It can be easily coated when the thickness of the shielding layer is relatively large.

The second method is a composite spinning method in which a fiber comprising a core and a sheath layer is spun and a light shielding layer is formed at the same time, and a core resin, a sheath resin and a coating resin composition are almost simultaneously formed in a multilayer composite. This is a method in which the wire is supplied to the spinning die and the wire is produced at a stroke.

Comparing the first method and the second method, in the first method, since the resin of the light shielding layer is not stretched, even if the element wire is heated, there is little shrinkage. On the other hand, in the case of the second method, as a process of producing a plastic optical fiber, a normally spun fiber is stretched to about 1.5 to 2 times, and a step of improving strength is performed. The degree of shrinkage due to heating is not so different from that of the strand obtained by the first method, probably because the light shielding layer contains carbon black. In addition, in this case, the sheath layer and the light shielding layer are completely fused and integrated, and furthermore, they are reinforced in a stretched manner, which is advantageous in terms of strength.

The plastic optical fiber of the present invention comprises:
It can completely shield the light from the outside as it is, and the covering strength is sufficient.The light shielding layer and the sheath layer are integrated, so if it is used as it is in the past, there is a problem in weather resistance. It can be used for applications such as light guides and displays that occur, and because it is thinner because there is no outer coating layer, signal wiring in equipment that wants to be wired as compact as possible in dimensions and optical coupling parts such as couplers It is also suitable for applications such as wiring and photoelectric sensors.

Further, in order to impart mechanical strength, chemical resistance, fashionability, discrimination and the like, the plastic optical fiber cable of the present invention in which the above-mentioned wire is further provided with an outer coating layer is preferable. In particular, in order to impart distinctiveness and fashionability, an outer coating layer colored in various clear colors is required.

In the present invention, as the thermoplastic resin forming the outer coating layer, generally used polyvinyl chloride, polyethylene, polyurethane, polyester, thermoplastic polyolefin elastomer and the like can be used, and a coloring agent is appropriately selected according to a desired color. Can be added for coloring. In the present invention, since the light shielding effect is obtained by the light shielding layer constituting the strand, the outer coating layer may be transparent or opaque, and may be colored white to black or any other color.

The plastic optical fiber cable according to the present invention is a cable suitable for wiring inside a moving body such as automobile wiring, marine wiring, aircraft wiring and the like. In the wiring in these moving objects, cables that are colored in many colors are required for identification of individual cables, and therefore, the cable of the present invention, which can be colored in any color, is suitable. In particular, considering the durability in high temperature environment and low temperature environment, the chemical resistance and mechanical strength to withstand gasoline and engine oil, etc.,
It is preferable to use a polyamide resin for the outer coating layer. The polyamide resin has very good compatibility with the strand of the present invention.
When the cable of the present invention in which the outer coating layer is formed of a polyamide resin is placed under the respective environments of 5 ° C., 100 ° C., and 120 ° C., the wire is retracted at the tip of the cable (the wire and the outer coating layer due to heat shrinkage). ) Was within 1.0 mm, a good result was obtained. Here, the polyamide resin is preferably nylon 12 or nylon 11.
The outer coating layer according to the present invention is also formed by coating a resin wire that has been hot-melted with a crosshead die onto a strand.

[0028]

【Example】

Example 1 A core diameter of 940 μm and a sheath diameter of 960 μm using PMMA as a core resin and a copolymer of fluoroalkyl methacrylate and methyl methacrylate as a sheath resin.
m (trade name: Luminous TB-960, manufactured by Asahi Kasei Kogyo Co., Ltd.), and as a coating resin composition for forming a light shielding layer, a copolymer comprising 90% by weight of vinylidene fluoride and 10% by weight of hexafluoropropene A resin composition in which 5% by weight of carbon black was kneaded was used. The melt flow index of the coating resin composition is 230 ° C.
3.8kg load, orifice diameter 2mm, length 8mm
Was 30 g / 10 min.

The above fiber was introduced into a crosshead die, and the coated resin composition was coated to a thickness of 20 μm at 230 ° C. to form a strand having an outer diameter of 1.00 mm. Then
Nylon 12 brightly colored orange as outer coating layer
With a crosshead die at a coating temperature of 220 ° C. to form a cable having a final outer diameter of 2.2 mm.

The above wires and cables were examined for the influence of external light. A wire and a cable each having a length of 50 m were prepared, both ends were fixed to black connectors, and the optical power was measured while passing 657 nm LED light through a toslink tester.

First, in the case of a strand, the light power in a dark room is -28.10 dBm, and then the same strand is exposed to clear direct sunlight, but the light power is -28.10 dBm, and Turned out to be unaffected. Also,
About the cable, almost the same value as the bare wire was obtained.

Next, the reliability of the cable under high temperature was examined. It was left at a high temperature of 85 ° C. and 105 ° C. for 2,000 hours, and a change in transmission loss was measured. As a result, there was no increase in transmission loss. In addition, when the protruding or retracting state of the outer coating layer / light shielding layer / fiber at the tip of the cable was examined, the light shielding layer and the tip of the fiber were uniform in any cable left at any temperature. As for the strands, although the cables left at 85 ° C are ready,
In the cable left at 105 ° C, the strand is 0.3 m
m. This degree of retraction had no problem during actual use, and it was found that the cable of this example had sufficient heat resistance.

Furthermore, even when the cable higher 120 ° C. than the T _g of a core resin PMMA for 24 hours, retraction of the strand remains in 0.5 mm, holding the entire length of the cable to 99.4% And high heat resistance was proved.

Example 2 A PMMA resin was used as the core resin, the same copolymer of fluoroalkyl methacrylate and methyl methacrylate as in Example 1 was used as the sheath resin, and vinylidene fluoride was used as the coating resin composition.
A mixture of 9% by weight and 28.1% by weight of tetrafluoroethylene kneaded with 2% by weight of carbon black was used. The melt flow index of these resins was 1.5 g / 10 min, 40 g / 10 min under the same conditions as in Example 1.
Min, 35 g / 10 min.

The above-mentioned resin is spun at 250 ° C. with a die for simultaneous spinning of three layers, stretched 2.0 times and heat-treated to obtain a core diameter of 950 μm, a sheath diameter of 970 μm, and an outermost diameter of 1.0 mm (that is, a light shielding layer). (Having a thickness of 15 μm).

The above strand was covered with nylon 12 colored bright orange. The coating was performed at 220 ° C. by introducing the above-mentioned wires into a crosshead. The outer diameter of the obtained cable was 2.2 mm.

The optical power of the wire and the cable was measured in the same manner as in Example 1. As a result, the optical power of the wires in a dark room is -28.10 dBm, when exposed to direct sunlight-
At 28.05 dBm, it was a level that did not cause a substantial problem. The cable was -28.10 in a dark room.
dBm was -28.09 dBm under direct sunlight, which was not a problem.

Further, the heat resistance of the cable was examined in the same manner as in Example 1. As a result, there is no increase in transmission loss at any temperature of 85 ° C and 105 ° C, and the protruding and retracting at the cable tip is about 0.1 mm at 85 ° C and about 0.5 mm at 105 ° C, respectively. Sufficient heat resistance was shown only to the extent of being retracted inside the outer coating layer. Further, even at 120 ° C., the retraction of the wire remained at 0.6 mm, and the total length of the cable was kept at 99.3%.

Comparative Example 1 A cable was manufactured in exactly the same manner as in Example 1 except that carbon black was not added to the light shielding layer, and the optical power was measured. As a result, the optical power of the cable in a dark room is -28.10.
dBm, but when exposed to direct sunlight-
It increased to 24.0 dBm, and it was found that external light had a large effect despite the presence of the outer coating layer.

[0040]

As described above, the plastic optical fiber of the present invention has light shielding properties and heat resistance, and in particular, the plastic optical fiber cable of the present invention having an outer coating layer formed thereon. In particular, a cable formed with an outer coating layer made of a polyamide resin is a cable that is less likely to be retracted even at a high temperature, has excellent heat resistance, and is particularly suitable for wiring in a moving body.

[Brief description of the drawings]

FIG. 1 is a sectional view of a plastic optical fiber cable of the present invention.

[Explanation of symbols]

 Reference Signs List 1 core 2 sheath layer 3 light shielding layer 4 plastic optical fiber strand 5 outer coating layer 6 plastic optical fiber cable

Claims (3)

[Claims] 1. A core comprising a polymethyl methacrylate resin, a sheath layer surrounding the core and comprising a transparent fluororesin having a lower refractive index than the core, and a vinylidene fluoride structural unit of 50% by weight or more. A light shielding layer comprising a coating resin composition obtained by adding carbon black to a vinylidene fluoride resin and having a thickness of 3 μm to 300 μm in close contact with the outside of the sheath layer; Strand. 2. A plastic optical fiber cable further comprising an outer coating layer made of a thermoplastic resin outside the plastic optical fiber strand according to claim 1. 3. The plastic optical fiber cable according to claim 2, wherein said thermoplastic resin is a polyamide resin.