JP3091239B2 - Plastic optical fiber cord - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In the present invention, when an end of an optical fiber cord is connected to various devices, the flame-retardant jacket layer of the optical fiber cord can be easily removed. The present invention also relates to an optical fiber cord having characteristics that do not cause a change in the optical transmission characteristics of the optical fiber cord and has good end face processing properties.

[0002]

2. Description of the Related Art Conventionally, plastic optical fiber cords are made of low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, soft vinyl chloride resin or the like as a jacket material. Particularly, in recent years, demand for an optical fiber cord using a soft vinyl chloride resin as a jacket material has been increased due to a demand for a flame retardant market. However, in order to use the vinyl chloride resin as a coating material for the optical fiber cord, it is necessary to soften the vinyl chloride resin, and for that purpose, it is necessary to contain a plasticizer in an amount of 20 to 200% by weight based on the vinyl chloride resin. As a plasticizer, di (2-ethylhexyl) phthalate (DOP) is most frequently used. When these soft vinyl chloride resins are coated on the plastic optical fiber, the plasticizer in the vinyl chloride resin migrates into the fiber, causing cracks in the optical fiber and the mechanical strength. However, there is a drawback that the optical transmission loss is reduced and the optical transmission loss is increased, which causes a serious problem in practical use. Japanese Patent Laid-Open No. 63-113 discloses a solution to this problem.
No. 511 discloses an invention in which a functional protective layer with less migration of a plasticizer is provided.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a method for coating a plasticized vinyl chloride resin on an optical fiber coated with a nylon-based polymer or an ethylene-vinyl alcohol-based polymer having a plasticizer transfer preventing effect as a protective layer substrate. However, it is difficult to pull out the vinyl chloride resin layer at the time of treating the end face of the optical fiber cord, which is a serious problem when the optical fiber cord is actually used.

[0004]

The present inventors have SUMMARY OF THE INVENTION As a result of investigations to find a plastic optical fiber cord obtained by solving the above problems, which the present invention has been completed, and its gist, plastic The outer layer of the optical fiber is coated with a polymer having a solubility parameter of 10 or more (No.
One coating layer) , and further, the outer layer has a fluorine content of 10 wt%.
The above polymer (A) is coated with 0.1 to 10 μm (second coating).
Cover layer ) and a soft vinyl chloride resin coating layer on the outer layer.
(Third coating layer) .

The core material of the optical fiber used in carrying out the present invention is preferably an amorphous transparent polymer, for example, a homopolymer or a copolymer of methyl methacrylate. As a copolymer of methyl methacrylate, 70% by weight or more of the starting monomer is methyl methacrylate, 30w
Preferably, t% or less is a monomer copolymerizable with methyl methacrylate. Examples of monomers copolymerizable with methyl methacrylate include vinyl monomers such as methyl acrylate and ethyl acrylate. Other polymers used as a core material include, for example, cyclohexyl methacrylate, t-butyl methacrylate, isobornyl methacrylate, adamantyl methacrylate, benzyl methacrylate, phenyl methacrylate, naphthyl methacrylate, and the like. Homopolymer of methacrylic acid ester or copolymer with monomer copolymerizable with them, polycarbonate, polystyrene, styrene-methacrylic acid ester copolymer, or all or a part of hydrogen atoms of these polymers are deuterium atoms A deuterated polymer substituted by the general formula (1)

Embedded image A polymer consisting of 2% by weight or more of the ring structural unit represented by the formula and 98% by weight or less of the monomer unit containing methyl methacrylate as a main component, or the fluorine content in the structural unit for applications requiring low loss. Is preferably 30% by weight or more. Specific examples thereof include a polymer having the following general formula (2) as a main monomer.

Embedded image

Further, Japanese Patent Application Laid-Open No. 63-261204 or US Pat.
A perfluoropolymer having a ring structure as exemplified in Japanese Patent Publication No. 4 (JP-A) No. 4 can be used.

[0007] sheath material of the optical fiber used in the present invention has substantially transparent polymer having 0.01 or more refractive index smaller than the refractive index of the core material is used, usually the difference in refractive index between the core material Is preferably in the range of 0.01 to 0.15.
The type of the sheath material is not particularly limited and may be a conventionally known material . For example, when a homopolymer or copolymer of methyl methacrylate is used as a core, JP-B-43-8978, JP-B-56-8321 No. 56-8322, JP-B-56-8323 and JP-A-53-60243, which are obtained by polymerizing esters composed of methacrylic acid and fluorinated alcohols. Can be used.

Further, polycarbonate or polystyrene is used.
When used as a core material , for example, polymethyl methacrylate can be used as a sheath material. Examples of other sheath materials include vinylidene fluoride-based polymers, vinylidene fluoride-hexafluoropropylene-based copolymers described in, for example, JP-B-43-8978 or JP-B-53-42260. Examples thereof include methacrylic acid ester-based polymers other than the above-mentioned polymethyl methacrylate, methylpentene-based polymers, and (co) polymers of esters composed of α-fluoroacrylic acid and fluorinated alkyl alcohol or alkyl alcohol. Further, a perfluoropolymer having a ring structure as described in U.S. Pat. No. 3,980,030 and JP-A-63-261204 can also be used.

The polymer for forming the first coating layer of the optical fiber cord of the present invention has the effect of preventing the plasticizer in the soft vinyl chloride resin disposed on the outer layer from migrating to the optical fiber . In order to exhibit this effect efficiently, a polymer having an SP value apart from the solubility parameter (SP) of the plasticizer is preferable. Solubility parameter of the plasticizer is mostly 7-9, first recording
As the covering polymer, aliphatic polyamide, aromatic polyamide (SP value: 12 to 16), polyvinyl alcohol (SP)
Value 19) and vinyl alcohol and ethylene, vinyl acetate, vinyl acrylate, acrylonitrile polymer
-And the like .

[0010] The second object covers the outer layer of the first coating layer
As the polymer (A) forming the cover layer, a fluorine-based polymer having poor adhesion to a soft vinyl chloride resin, particularly a polymer having a fluorine content of 10 wt% or more is preferable. Second coating layer formed by the polymer of less than fluorine content 10 wt% is not sufficient non-stick properties of its surface, when the end face machining of the optical fiber cord having a third coating layer constituted by a soft vinyl chloride, the strong pull-out strength of the three coating layers, the third at the end face
When the coating layer is pulled out, inconveniences such as stretching of the optical fiber and scratching of the optical fiber surface occur.

As the polymer which can be used as the polymer (A), a homopolymer of vinylidene fluoride or vinylidene fluoride and ethylene, tetrafluoroethylene, chlorotrifluoroethylene, propylene hexafluoride, perfluorovinyl ether, or the like can be used. A copolymer, a fluorinated alkyl ester acrylate or methacrylate polymer,
Typical examples thereof include an α-fluoroacrylate polymer, a tetrafluoroethylene-ethylene copolymer, a propylene hexafluoride-based polymer, and a perfluorovinyl ether-based polymer, but are not limited thereto.

An optical fiber cord obtained from an optical fiber having a second coating layer having a thickness of less than 0.1 μm has a third coating layer.
The pullout strength is very strong, and, since the formation of the uniform layer of the polymer (A) becomes difficult, resulting in variations in the pullout strength of the third coating layer.

On the other hand, the thickness of the second coating layer is 10 μm.
When bending the optical fiber beyond the limit, the polymer (A) is easily peeled off, and the optical transmission characteristic of the optical fiber cord is liable to change.

As a method for producing the plastic optical fiber cord of the present invention, there are a method using only a melt spinning method, a method using an optical fiber strand by a melt spinning method, and a combination with a coating process such as coating. Can be
Melt spinning only methods include core, sheath, first coating
The so-called composite spinning method, in which the base material of each of the layer, the second coating layer and the third coating layer is arranged in a molten state in a concentric five-layer structure by a special nozzle, discharged and shaped, is preferred. is there. Further, as a method of combining spinning and coating processing, a method of spinning only the core or a composite spin of the core and the sheath, shaping, and sequentially coating other constituent layers on the shaped material, etc. Is used.

[0015] The optical fiber cord of the present invention is an optical fiber outside
With a first coating layer of a polymer having a specific SP value around the circumference ,
In addition, since a second coating layer of a fluororesin having a specific thickness is provided on the outside thereof, the plasticizer is used despite the structure in which a soft vinyl chloride resin is provided as a third coating layer . There is no deterioration in the optical transmission characteristics of the optical fiber cord due to migration into the inside, and further, the handleability is excellent, in which the peeling treatment of the third coating layer at the time of processing the end face can be easily performed.

[0016]

The present invention will be described in more detail with reference to the following examples.

[0017]

Example 1 100 parts of methyl methacrylate and 0.40 part of t-butyl mercaptan were obtained by a continuous bulk polymerization method using a reaction tank equipped with a spiral ribbon type stirrer and a volatile substance separation apparatus comprising a twin screw vent type extruder. And di
A monomer mixture consisting of 0.00017 parts of t-butyl peroxide was reacted at a polymerization temperature of 155 ° C. and an average residence time of 4.0 hours.
The volatile part was separated at 60 ° C., the extruded part 250 ° C., and the vent part vacuum degree was 4 mmHg, and the core-sheath- first coating at 230 ° C. was passed through a gear pump part kept at 230 ° C. as a core component polymer.
The layer was fed to a three component composite spinning head.

On the other hand, a sheath component comprising a copolymer of 2,2,2-trifluoroethyl methacrylate / 1H, 1H, 2H, 2H-fluorodecyl methacrylate / methyl methacrylate / methacrylic acid = 40/40/19/1% by weight. The polymer was fed to a composite spinning head at 230 ° C via a gear pump by a screw melt extruder set at 220 ° C.

As the first coating layer outside the sheath material,
The 12 nylon resin was fed to the composite spinning head at 230 ° C via a gear pump by a screw melt extruder set at 240 ° C. The molten polymer of the core-sheath and the first coating layer supplied at the same time is subjected to spinning using a spinneret (nozzle hole diameter: 3 mm).
After being discharged at 30 ° C., cooled and solidified, it was taken up at a speed of 3 m / min and wound up to obtain a plastic optical fiber having an outer diameter of 980 μm, a sheath material thickness of 8 μm, and a first coating layer thickness of 10 μm. . In addition, vinylidene fluoride /
A solution prepared by dissolving a copolymer of hexafluoropropylene = 90/10 mol% in acetone at 20% by weight is applied and dried.
The second coating layer was coated to a thickness of 5 μm to obtain a fiber core.

Next, a soft vinyl chloride resin was coated as a third coating layer on the fiber core wire with a crosshead die cable processing machine to obtain an optical fiber cord having an outer diameter of 2.0 mm. The composition of the soft vinyl chloride resin used for the coating material was 100 parts of vinyl chloride, 50 parts of DOP, 2 parts of dioctyltin mercapto, 0.5 part of butyl stearate, and 0.3 part of stearyl alcohol.

The obtained optical fiber cord is
A migration test of the plasticizer was performed by exposing to a high temperature of 100 ° C. for 100 hours, and the repetitive flexibility of the following optical fiber cord and the optical transmission loss after these tests were evaluated by the following evaluation methods.
Table 1 shows the results.

[Evaluation Method] A repetitively bendable optical fiber cord was sandwiched between two mandrels having a diameter of 10 mmφ and bent 90 ° each left and right, and the number of bends at which the light amount holding ratio became 50% was read.

Optical transmission loss Measured according to the method described in JP-A-58-7602. The measurement wavelength was 650 nm, and the fiber incident light used was a light having a numerical aperture of 0.6.

Jacket pull-out characteristics The third coating layer was pulled out from a position 40 mm from the end face of the optical fiber cord using a wire stripper. At this time, the results of visual observation of the appearance damage and change of the fiber core wire are shown in Table 1. Was.

[0025]

Examples 2-3 and Comparative Examples 1-4 For forming the first coating layer
The polymer shown in Table 1 was used for forming the second coating layer, and the light was coated with the vinyl chloride resin in the same manner as in Example 1 except for the above.
Fiber cord was obtained. Table 1 shows the evaluation results.

[0026]

[Table 1]

[0027]

Example 4 A bisphenol A-type polycarbonate having an average viscosity of 22,000 was melted by a vent extruder having a vent portion of 260 ° C., an extruding portion of 240 ° C., and a vent portion vacuum of 50 mmHg. Was supplied to the core-sheath- first coating layer three-component composite spinning head at 230 ° C. through a gear pump section maintained at a temperature of 650 ° C.

On the other hand, perfluoro (2,2-dimethyl-
1,3-dioxole) / tetrafluoroethylene = 6
0/40 mol% of a copolymer as a sheath component forming polymer
It was melted at an extrusion temperature of 30 ° C and fed to the spinning head via a gear pump kept at 230 ° C. Further, as a first coating layer on the outer side of the sheath material, an ethylene-vinyl alcohol copolymer (ethylene / vinyl alcohol = 32/68 mol%) was melted at an extrusion temperature of 220 ° C, and a gear pump kept at 230 ° C was used. After that, it was supplied to the spinning head.

The molten polymer of the core-sheath and the first coating layer supplied at the same time is discharged at 230 ° C. using a spinneret (nozzle diameter of 3 mm), cooled and solidified, and then taken out at a speed of 3 m / min. Then, a plastic optical fiber having an outer diameter of 980 μm, a sheath portion thickness of 8 μm, and a first coating layer thickness of 10 μm was obtained. Further, a liquid obtained by dissolving 20% by weight of a copolymer of vinylidene fluoride / tetrafluoroethylene = 80/20 mol% in acetone was applied to the outer layer and dried.
The second coating layer was coated to a thickness of 5 μm to obtain a fiber core.

Next, a soft vinyl chloride resin was coated as a third coating layer on the core fiber with a crosshead die cable processing machine to obtain an optical fiber cord having an outer diameter of 2.0 mm. The composition of the soft vinyl chloride resin used for the coating material was 100 parts of vinyl chloride, 50 parts of DOP, 2 parts of dioctyltin mercapto, 0.5 part of butyl stearate, and 0.3 part of stearyl alcohol. The optical fiber cord thus obtained was exposed to a high temperature of 125 ° C. for 100 hours to conduct a migration test of a plasticizer to evaluate the repetitive flexibility and increase in light transmission loss. The results are shown in Table 2.

[0031]

Examples 5 and 6, Comparative Examples 5 and 6 First coating layer and second coating layer
A vinyl chloride-coated optical fiber cord was obtained in the same manner as in Example 4, except that the polymers shown in Table 2 were used for forming the cover layer . Table 2 shows the evaluation results.

[0032]

[Table 2]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-113511 (JP, A) JP-A-57-71830 (JP, A) JP-A-61-198112 (JP, A) JP-A-61-1981 196211 (JP, A) Japanese Patent Laid-Open No. 3-50511 (JP, A) Japanese Utility Model Publication No. 58-7362 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/00-6 / 54

Claims (1)

(57) [Claims] 1. A polymer (A) in which the outer layer of a plastic optical fiber is coated with a polymer having a solubility parameter of 10 or more, and the outer layer has a fluorine content of 10 wt% or more.
A plastic optical fiber cord, which is coated with a soft vinyl chloride resin coating layer on its outer layer.