JP2007272013A - Plastic optical fiber cord and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic optical fiber cord having small diameter used for an optical waveguide or the like, which is made by coating the outside of a plastic optical fiber having a small diameter with polyamide resin having a high melting temperature, and to provide a method of manufacturing the same. <P>SOLUTION: The plastic optical fiber cord is obtained by forming a coating layer on an optical fiber composed of a core and a clad. The plastic optical fiber cord is characterized in that the diameter of the plastic optical fiber is 500 μm or smaller and the coating layer is formed of at least two layers of polyamide resin composed of the same polymer composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plastic optical fiber cord and a manufacturing method thereof, and more particularly to a small-diameter plastic optical fiber cord used for an optical waveguide and the like and a manufacturing method thereof.

  Plastic optical fibers are superior to glass-based optical fibers in terms of processability, handleability, and manufacturing cost, and are widely used for short-distance optical signal transmission, lighting light guides, and the like. For the purpose of protecting plastic optical fibers, plastic optical fiber cords with a coating layer on the outer periphery of plastic optical fibers are known, and are used in fields such as photoelectric sensors, optical signal transmission, and recently in-vehicle information communication applications. Has been. As the plastic optical fiber core wire used for the plastic optical fiber cord, one having a diameter of about 1,000 μm is generally used as shown in Patent Documents 1 to 3, for example, from the viewpoint of the amount of light received and handling properties. Yes. Moreover, as a thin plastic optical fiber cord using a plastic optical fiber having a diameter of 500 μm or less, a thin plastic optical fiber cord as disclosed in Patent Document 4 has been proposed.

  On the other hand, flexible printed circuits are used as signal transmission media in various electrical devices such as cameras, printers, personal computers, mobile phones, and liquid crystal displays. However, in recent years, with the increase in the amount of data to be transmitted, an optical waveguide or the like as in Patent Document 5 has been proposed as a communication medium that replaces a flexible printed circuit. Further, a technique for connecting each printed wiring board with a single optical fiber as described in Patent Document 6 has been proposed. A film-shaped optical waveguide has a transmission loss of about 20 dB / m at a wavelength of 1,310 nm, whereas a plastic optical fiber has a transmission loss of about 0.3 dB / m at a wavelength of 650 nm compared to the optical waveguide. And very small. For this reason, attention has been focused on the use of plastic optical fibers for optical waveguides in optical waveguide applications where an optical transmission system with a low-output light source is assumed. Applications of these technologies are expected to expand in the future, and can be applied to mobile phones and notebook computers. However, in order to use a plastic optical fiber cord, for example, when connecting a printed wiring board of a foldable mobile phone and a liquid crystal display, it must be wired in a slight gap and bend flexibly. The characteristic that it has to be needed. Therefore, it has become important to develop plastic optical fiber cords with the smallest possible diameter.

On the other hand, in order to connect an optical member such as a light source and a plastic optical fiber cord, it is necessary to attach connectors to both ends of the plastic optical fiber cord. The connector includes a metal, a resin, and a ceramic, and can be attached to the plastic optical fiber cord by adhesion, fusion, caulking, or the like. In recent years, as a method of connecting a connector to both ends of a plastic optical fiber cord, there is a method of laser welding a nylon resin connector and a plastic optical fiber cord coated with a nylon resin, as it can be realized in a small size, light weight, and simplification. It has been adopted. The plastic optical fiber cords described in Patent Documents 1 to 3 have also been developed with this connection method in mind. The laser fusion method is considered to be the best for connector connection in the application to the mobile phone described above. However, in the thin plastic optical fiber cord described in Patent Document 4 described above, the coating material is a polyolefin resin, and is not suitable for laser fusion with a nylon connector.
JP 11-242142 A JP 2002-098865 A Japanese Patent Laid-Open No. 10-319281 JP 2005-326501 A JP 2003-227951 A JP 09-270751 A

  For these reasons, it has become necessary to develop a thin plastic optical fiber cord in which the outer periphery of the thin plastic optical fiber is coated with a nylon resin connector and a polyamide resin capable of laser fusion.

  However, in the conventional technology, when trying to coat a polyamide resin with a high melting temperature on a small-diameter plastic optical fiber, the plastic optical fiber core wire is disconnected at the time of coating due to the influence of the melting heat of the polyamide resin, so that coating is possible. There was a problem that I couldn't.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and to coat a plastic optical fiber with a resin that can be laser-fused around the outer periphery of the plastic optical fiber, and to manufacture a small-diameter plastic optical fiber cord used for optical waveguide applications and the like. It is to provide a method.

In order to achieve the above object, the present invention mainly has the following configuration.
That is, the present invention is a plastic optical fiber cord in which a coating layer is provided on an outer layer of a plastic optical fiber composed of a core and a cladding, and the diameter of the plastic optical fiber is 500 μm or less, and the coating layer is A plastic optical fiber cord formed of a polyamide resin composed of at least two layers of the same polymer component.

  According to another aspect of the present invention, there is provided a plastic optical fiber cord characterized in that a coating layer in contact with a plastic optical fiber among two or more coating layers is coated so that the thickness thereof is not more than 0.25 times the diameter of the optical fiber. is there.

  The present invention also provides a plastic optical fiber that is passed through a die nipple having a hollow structure to form a coating layer, and then the coated plastic optical fiber cord is cooled with a water temperature of 10 ° C. or less within 0.4 seconds. After cooling with a die nipple having a hollow structure, a coating layer is further formed on the outer periphery of the plastic optical fiber, and then the coated plastic optical fiber cord is coated with a water temperature within 0.4 seconds after coating. A method for producing a plastic optical fiber cord, wherein the plastic optical fiber cord is brought into contact with cooling water of 10 ° C. or lower.

  According to the plastic optical fiber and the manufacturing method thereof of the present invention, a thin plastic optical fiber cord for use in an optical waveguide or the like, in which a polyamide resin having a high melting temperature is coated on the outside of a thin plastic optical fiber. Can be manufactured.

  FIG. 1 shows a schematic cross-sectional view of one embodiment of the plastic optical fiber cord of the present invention. In the figure, 1 is a plastic optical fiber, 2 is a coating layer A in contact with the plastic optical fiber, and 3 is a coating layer B coated on the outer periphery of the coating layer.

  The core material of the plastic optical fiber effective in the present invention is a (co) polymer mainly composed of methyl methacrylate, and is a copolymer containing polymethyl methacrylate (hereinafter referred to as PMMA) or 70% by weight or more of methyl methacrylate. For example, a methyl methacrylate copolymer containing, for example, (meth) acrylic acid ester, (meth) acrylic acid, (substituted) styrene, (N-substituted) maleimide as a copolymer component, or glutar obtained by polymerizing them. Examples thereof include polymers modified with acid anhydrides, glutarimide and the like. Examples of (meth) acrylic acid esters include methyl acrylate, ethyl methacrylate, butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, phenyl methacrylate, bornyl methacrylate, and adamantyl methacrylate. Substituted styrene includes methyl styrene. Α-methylstyrene, N-substituted maleimides include N-isopropylmaleimide, N-cyclohexylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-o-methylphenylmaleimide and the like. A plurality of these copolymer components may be used, and a small amount of other components may be used. Further, a stabilizer such as an antioxidant may be contained in an amount that does not adversely affect the light transmission property. Among these polymers, PMMA is most preferable from the viewpoints of productivity, translucency, environmental resistance and the like.

  Copolymers forming the cladding of the plastic optical fiber effective in the present invention are vinylidene fluoride / tetrafluoroethylene copolymer, vinylidene fluoride / hexafluoroacetone copolymer, vinylidene fluoride / hexafluoropropylene copolymer, And vinylidene fluoride-based (co) polymers such as vinylidene fluoride homopolymer. The thickness of the clad is preferably 2 to 20 μm. The thickness is preferably thin enough not to cause a problem in characteristics, and more preferably 3 to 10 μm.

  In the present invention, a polyamide resin is coated on a plastic optical fiber having a diameter of 500 μm or less among the plastic optical fibers as described above. If the diameter of the plastic optical fiber exceeds 500 μm, the outer diameter after coating becomes too thick, which is not preferable. The diameter is usually 10 μm or more.

  A polyamide resin is coated on the outer periphery of the plastic optical fiber so as to be in contact with the plastic optical fiber. At this time, the thickness of the polyamide resin coating layer is preferably 0.25 times or less the diameter of the plastic optical fiber. The temperature at the time of coating with the polyamide resin is close to 200 ° C., whereas the heat resistance temperature of the plastic optical fiber is from 70 ° C. to about 115 ° C. at the highest, so if the thickness of the coating layer becomes too thick, There may be a problem that the light transmission loss is extremely deteriorated or that the plastic optical fiber is disconnected at the time of coating.

  Examples of the polyamide resin used in the present invention include nylon 6, nylon 66, nylon 11, nylon 12, and the like, those containing a plasticizer in nylon 12, copolymers of nylon 12 and other nylons such as nylon 6, poly Nylon elastomer which is block copolymerization with ether, polyester and the like. Among these, nylon 12 is particularly preferable from the viewpoints of bending resistance, bending resistance, environmental resistance, laser fusion with a connector, and the like.

  The coating layer needs to be at least two layers, and the coating layer A that contacts the optical fiber and the coating layer B that covers this outer peripheral portion must be coated with the same polyamide resin. The coating is performed so that the outer diameter of the plastic optical fiber cord is a desired outer diameter. If the desired outer diameter is not reached once, the outer layer may be further coated in the same manner. By coating the coating layer a plurality of times, it is possible to create a coating thickness that is optimal for laser fusion.

  Covering a plastic optical fiber having a diameter of 500 μm or less with a polyamide resin, as described above, the plastic optical fiber core wire is broken during coating due to the heat of fusion of the polyamide resin, and cannot be coated. However, the method of the present invention, that is, a plastic optical fiber, was made possible only by forming a thin layer of polyamide first and then forming a further layer of polyamide on the outside. Each layer constituting the coating is made of polyamide with the same polymer component, so that the inner coating layer and the outer coating layer are firmly adhered to each other, and the plastic optical fiber cord can be stably stabilized without shifting or breaking the coating. Can be manufactured.

  FIG. 2 is a schematic side sectional view showing one embodiment of a coating process which is a production method of the present invention. The coating process for coating the coating layer 2 of the plastic optical fiber cord of this embodiment is by melt extrusion using a crosshead. Here, the die 5 and the nipple 4 of the crosshead have a hollow structure. If the die and nipple have a solid (pressurized) structure, the plastic optical fiber is disconnected during coating, which is not preferable.

  The manufacturing method of the present invention includes a cooling step of cooling the coated plastic optical fiber cord with the cooling water in the cooling water tank 6. The water temperature of the cooling water at this time is preferably 10 ° C. or lower, and it is preferable to start cooling with the cooling water within 0.4 seconds after coating. If the temperature of the cooling water is higher than 10 ° C., the cooling effect is poor, and as a result, the light transmission loss of the plastic optical fiber cord is deteriorated, or the plastic optical fiber is disconnected during coating. Further, if the time until cooling after coating exceeds 0.4 seconds, it is not preferable because deterioration of light transmission loss and disconnection at the time of coating occur.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
A plastic optical fiber core wire having a diameter of 250 μm, in which the core material is PMMA (refractive index 1.492) and the clad material is a copolymer of hexafluoropropylene / tetrafluoroethylene (refractive index 1.378) is obtained by melt compound spinning. Manufactured. Next, a coating resin in which nylon 12 (L1640 made by Daicel Degussa) and black color master (PAM (F) 138 (D) made by Dainichi Seika) were mixed at a ratio of 10: 1 to this optical fiber core wire was used with a crosshead. Using a melt extrusion molding machine, the molten resin was discharged so as to have a thickness of 50 μm (0.2 times the fiber diameter) to form a coating layer A. At this time, the die nipple during coating had a hollow structure, and the coating resin temperature during coating was 195 ° C. Further, the coating linear velocity of the plastic optical fiber core wire was 60 m / min, the cooling water temperature for cooling the coating layer A was 10 ° C., and the distance from the crosshead end surface to the cooling water was 10 cm. The time until cooling after coating at this time was 0.1 seconds in calculation.

  Next, the outer circumference of the coating layer A was coated by discharging nylon 12 resin so that the outer diameter of the plastic optical fiber cord was 500 μm. The coating linear velocity, the cooling water temperature, and the distance to the cooling water were the same as those of the coating layer A. By the above manufacturing method, a nylon 12-coated plastic optical fiber cord having a plastic optical fiber diameter of 250 μm and a coating outer diameter of 500 μm could be obtained. When the transmission loss of the obtained plastic optical fiber cord was measured by a 30 m / 2 m cutback method using halogen parallel light (wavelength 650 nm), a good result of 0.25 dB / m was obtained. .

[Comparative Example 1]
In order to obtain a nylon 12-coated plastic optical fiber cord having a plastic optical fiber diameter of 250 μm and a coated outer diameter of 500 μm, similar to that of Example 1, a plastic optical fiber core wire similar to that of Example 1 is used, which is a conventional manufacturing method 1 The coating was attempted so as to have a coating outer diameter of 500 μm by only one coating. Coating was attempted under the same conditions as in Example 1 except for the resin discharge amount, but the plastic optical fiber core wire was broken and could not be coated.

[Comparative Example 2]
In order to obtain a nylon 12-coated plastic optical fiber cord having a plastic optical fiber diameter of 250 μm and a coated outer diameter of 500 μm, the same as in Example 1, a plastic optical fiber core wire similar to that in Example 1 is used, and the die nipple has a full structure The coating was attempted under the same conditions as in Example 1 except that. When the resin was discharged to cover the coating layer A, the plastic optical fiber core wire was broken and could not be coated.

[Comparative Example 3]
In order to obtain a nylon 12-coated plastic optical fiber cord having a plastic optical fiber diameter of 250 μm and a coated outer diameter of 500 μm as in Example 1, the same plastic optical fiber core as in Example 1 was used, and the coated wire speed was 10 m / min. Coating was attempted under the same conditions as in Example 1 except that. The time until cooling after coating at this time was 0.6 seconds in calculation. When the resin was discharged to cover the coating layer A, the plastic optical fiber core wire was broken and could not be coated.

[Comparative Example 4]
In order to obtain a nylon 12-coated plastic optical fiber cord having a plastic optical fiber diameter of 250 μm and a coating outer diameter of 500 μm similar to that in Example 1, the same plastic optical fiber core wire as in Example 1 was used, and the cooling water temperature was set to 50 ° C. The coating was attempted under the same conditions as in Example 1 except that. As the coating layer A in contact with the optical fiber, nylon 12 was coated so as to have a thickness of 50 μm (20% of the fiber diameter). The outer periphery of the obtained plastic optical fiber cord was coated with a coating layer B with nylon 12 so that the outer diameter of the plastic optical fiber cord was 500 μm. The coating linear velocity, the cooling water temperature, and the distance to the cooling water were the same as those for the coating layer A. When the transmission loss of the obtained plastic optical fiber cord was measured by a 30 m / 2 m cutback method using halogen parallel light (wavelength 650 nm), it was as bad as 1.22 dB / m.

It is typical sectional drawing which shows the one aspect | mode of the plastic optical fiber cord in this invention. It is a side cross-sectional schematic diagram which shows the one aspect | mode of the coating process which is a manufacturing method of the plastic optical fiber cord in this invention.

Explanation of symbols

1 Plastic optical fiber 2 Coating layer A
3 Coating layer B
4 Die 5 Nipple 6 Cooling water tank

Claims (5)

  A plastic optical fiber cord in which a coating layer is provided on an outer layer of a plastic optical fiber composed of a core and a clad, wherein the plastic optical fiber has a diameter of 500 μm or less, and at least two coating layers are the same A plastic optical fiber cord formed of a polyamide resin composed of a polymer component of   2. The plastic light according to claim 1, wherein the thickness of the coating layer in contact with the plastic optical fiber among the two or more coating layers is coated so as to be not more than 0.25 times the diameter of the plastic optical fiber. Fiber cord.   3. The plastic optical fiber cord according to claim 1, wherein the polyamide resin contains nylon 12 as a main component.   The plastic optical fiber is passed through a die nipple having a hollow structure to form a coating layer in contact with the plastic optical fiber on the outer periphery of the plastic optical fiber, and then the coated plastic optical fiber cord is coated for 0.4 seconds. The manufacturing method of the plastic optical fiber cord according to any one of claims 1 to 3, wherein the plastic optical fiber cord is brought into contact with cooling water having a water temperature of 10 ° C or less.   After a plastic optical fiber is passed through a die nipple having a hollow structure to form a coating layer, the coated plastic optical fiber cord is cooled with cooling water having a water temperature of 10 ° C. or less within 0.4 seconds. After passing through a die nipple having a hollow structure again to form a coating layer on the outer periphery of the plastic optical fiber, the coated plastic optical fiber cord is coated and cooled to a water temperature of 10 ° C. or less within 0.4 seconds. The method for producing a plastic optical fiber cord according to claim 1, wherein the plastic optical fiber cord is brought into contact with water.

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