KR101234997B1 - Method for manufacturing multi-layer light transmission medium and plastic optical fiber - Google Patents

Abstract

The first layer raw material 21a containing the polymerizable compound and the polymerization initiator is supplied to the cylindrical first member 12. The first member is then rotated around the center of its circular cross section to polymerize the polymerizable compound to form the first layer 21. The reaction temperature TE1 (° C) in this polymerization step is determined to satisfy the formula represented by TE2-20 ≦ TE1 ≦ TE2 + 25, and TE2 (° C) represents the 10 hour half-life temperature of the polymerization initiator. Thereafter, the second layer raw material 22a is supplied to the hollow portion of the first layer. The first member is then rotated to polymerize the polymerizable compound at the reaction temperature of TE1 to form the second layer 22. The supply step and the polymerization step are alternately repeated several times to form a second member 16 composed of a plurality of layers in the first member.

Plastic optical fiber, optical transmission medium

Description

METHOD FOR MANUFACTURING MULTI-LAYER LIGHT TRANSMISSION MEDIUM AND PLASTIC OPTICAL FIBER}

The present invention relates to a method for producing a multilayer optical transmission medium and a method for producing a plastic optical fiber.

Optical transmission media such as optical fibers generally consist of a cover portion and a light guide portion, each having a different refractive index. Once entering the light guide, the optical signal is continuously reflected at the border of the cover, traveling along the axis of the optical transmission medium. Usually, a plastic optical transmission medium is formed by the stretching of a preform. However, the preform sometimes contains the residue of the polymerizable compound which failed to react in the polymerization step of the preform production process. These preforms foam as they are stretched, degrading their light transmission properties.

In view of the above problem, Japanese Patent Application Laid-Open No. 11-344623 discloses that a preform formed of a set of decreasing size cylindrical polymers disposed inside one of them has a reduced air pressure at a temperature above the glass transition temperature (Tg) of the polymer. Disclosed is a method for producing a plastic optical fiber which is heated under. By this manufacturing method, foreign matter is effectively removed from the preform, and thus hardly foamed when drawn. In addition, Japanese Patent Laid-Open No. 10-96825 discloses a method for producing a preform in which several polymer layers each layer contains a specific amount of unreacted monomers are disposed on top of each other. With this manufacturing method, the polymerization reaction in each polymer layer is continued before the polymerization initiator comes out. Thus, the polymerizable compound is effectively polymerized and the productivity of the preform is improved.

However, the manufacturing method of Unexamined-Japanese-Patent No. 11-344623 can deform | transform a preform according to the kind of material in the heating process of heating a preform at the temperature more than Tg. On the other hand, in the manufacturing method of JP-A-10-96825, the preform foams fairly easily because some unreacted monomers remain intentionally in the polymer layer. As a result, the productivity of the plastic optical fibers is reduced.

It is therefore a main object of the present invention to provide a method for producing a multilayer light transmission medium in which a polymerizable compound is polymerized effectively and efficiently.

Another object of the present invention is to provide a method for producing a bubble-free optical transmission medium having excellent optical transmission characteristics.

DISCLOSURE OF INVENTION

In order to achieve the above objects and other objects, the method for producing a multilayer light transmission medium according to the present invention is a supplying step of supplying a polymerizable compound and a polymerization initiator to a tubular container, the circular cross section of the tubular container until the polymerizable compound is polymerized. And a polymerization step of rotating the tubular vessel around the center, and a multilayer optical transmission medium forming step of alternately performing the supplying and polymerization steps several times to form a multilayer optical transmission medium composed of a plurality of concentric layers in the tubular vessel. The polymerization step is carried out at a reaction temperature TE1 (° C.) determined to satisfy the equation represented by:

TE2-20 ≤ TE1 ≤ TE2 + 25

In formula, TE2 (degreeC) shows the 10-hour half life temperature of a polymerization initiator. Preferably, the formula is TE2 ≦ TE1 ≦ TE2 + 20, more preferably TE2 ≦ TE1 ≦ TE2 + 10.

The polymerization step can preferably last from 0.5 hours to 5 hours.

The method for producing a plastic optical fiber according to the present invention includes the supplying step, the polymerization step, the multilayer optical transmission medium forming step, and also the first heating step, the second heating step and the stretching step. In the first heating step, the multilayer light transmission medium is heated for 24 to 72 hours. In the subsequent second heating step, when the Tg is the glass transition temperature of the polymer formed in the polymerization step, under air pressure reduced by 0.05 MPa to 0.1 MPa relative to atmospheric pressure, the multilayer optical transmission medium is subjected to (Tg- 10) It is heated at a heating temperature of at least C and less than Tg. In the stretching step, the multilayer light transmission medium is heated and stretched.

The heating temperature in the second heating step is preferably (Tg-8) ° C or more and less than Tg, and more preferably (Tg-5) ° C or more and less than Tg.

According to the present invention, the polymerizable compound polymerizes effectively and efficiently and hardly remains unreacted in the optical transmission medium. In addition, the polymerization reaction period can be shortened as compared with the conventional method, and an optical transmission medium having excellent transmission characteristics is effectively produced.

1 is a flowchart of a plastic optical fiber manufacturing process according to the present invention.

2 is a cross-sectional view of the preform.

3 is a cross-sectional view of the polymerization vessel in the first layer forming step.

4 is a schematic view of a rotary polymerization apparatus.

5 is an exemplary view showing the operation of the rotary polymerization apparatus.

6 is a cross-sectional view of the polymerization vessel in the second layer forming step.

Optimal for carrying out the present invention mode

1 and 2, a method 10 for producing a plastic optical fiber (hereinafter optical fiber) 19 forms a first member that forms a cylindrical first member 12 as an outer cover of the preform 11. Step (13), which heats the second member formation step (17) and the preform (11) in which the second layer (16) is formed as a light guide portion in the hollow portion of the first member (12) and constitutes the preform (11). The heating process 18 and the extending process in which the preform 11 is extended along the long side and becomes the optical fiber 19 are included.

The second member 16, which is composed of a plurality of layers laminated from the outside to the inside, has an n-layer concentric structure when viewed in cross section. Where n is a natural number greater than one. The second member 16 is composed of the first layer 21, the second layer 22, ....., the (nl) layer 23 and the nth layer 24 from the outside to the inside, These layers are respectively formed by the first layer forming process 31, the second layer forming process 32,..., The (nl) layer forming process 33, and the nth layer forming process 34, respectively. Is formed.

Each of the layers 21 to 24 has a uniform thickness along the long side and may or may not be the same thickness. The preform 11 of FIG. 2 has a hollow portion 27 in the middle of its circular cross section, and the hollow portion 27 may not be formed under constant forming conditions of the nth layer 24.

In this embodiment, the first member 12 is used as a container for the formation of the second member 16, and the single member first member 12 and the n layer second member 16 are integrally formed. To form (n + 1) preforms 11 with layers. The number of layers, the method of forming the first member 12, and the method of integrating the first member 12 and the second member 16 are not limited to the above. For example, a cylindrical first member may be formed first in the tubular container, and then (n-1) second members in the hollow portion of the first member may be formed to obtain a preform having n layers. . Alternatively, the cylindrical first member and the second member may be separately formed in the tubular container, and then the second member may be inserted into the first member to obtain a preform. To obtain the first member, the polymerizable compound is rotated in a tubular vessel to polymerize, or the polymer is processed by a melt-extrusion method.

The first layer forming process 31 includes a supplying step 37 for supplying the material for the first layer 21 into the hollow portion of the first member 12, and a polymerization step 38 for polymerizing the supplied material. Include. This forming process also applies to other layers, i.e., the second layer 22 to the nth layer 24, so in FIG. 1 only the first layer forming process 31 is supplied with the feeding step 37 and the polymerization step 38. Note that it is shown with. By alternately repeating the feeding step and the polymerization step, the layers of the second member 16 are formed sequentially from the outside.

The first member 12 is as low as 5 × 10 ⁻³ and has a higher refractive index than the adjacent first layer 21. In addition, the outer layer of the two adjacent layers in the second member 16 is as low as 5 × 10 ⁻³ , and has a higher refractive index than the adjacent inner layer. That is, the refractive index of the second member 16 increases toward the center of its circular cross section. In addition, the refractive index of the 1st layer 21, ie, the outermost layer of the 2nd member 16 is 1.4 or more and 1.5 or less. This structure serves to reduce transmission loss. Note that the refractive index of the second member 16 may vary continuously or stepwise.

The first member 12 is composed of a crystalline polymer. This polymer improves the ductility, strength, and other physical properties of the first member 12, and the optical fiber formed hardly deforms when it is banded. The polymerizable compound for the first member 12 is preferably selected from those having a crystalline structure and containing fluorine atoms. The first member 12 composed of such a polymerizable compound, when formed of optical fibers, becomes harder than the prior art and has a low refractive index. The polymerizable compound for the first member 12 is preferably polyvinylidene fluoride (PVDF), tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer (THV), tetrafluoroethylene hexafluoro propylene It may be a copolymer (FEP), or polytetrafluoroethylene perfluoro alkylvinyl ether (PFA), the most preferred of which is THV because of its low refractive index.

The second member 16 is composed of an amorphous polymer to prevent light diffusion, and these polymers are formed from a polymerizable compound capable of putting the layers together. It is more preferable to use a polymerizable compound having excellent mechanical properties and excellent heat and moisture resistance. An exemplary polymer for the first layer 21 is one having a low refractive index among ordinary polymers.

The polymerizable compound for the first layer 21 to the nth layer 24 may be, for example, (meth) acrylate [(a) fluorine-free (meth) acrylate, (b) fluorine-containing (meth) acrylate ], (c) styrene compounds, (d) vinyl esters, and (e) fluorine-containing backbone cyclic polymer forming monomers. Polymers for layers 21-24 include amorphous fluoro-type polymers (e.g., Teflon® AF (manufactured by EIdu Pont de Nemours & Company Inc.), AVA resins, norbornene-type resins (e.g. For example, it may be a polymer formed of ZEONEX (registered trademark, manufactured by ZEON corporation), a functional norbornene-type resin (eg, ARTON (registered trademark, manufactured by JSR)), or bisphenol-A. Affinity and refractive index Note that the conditions between two adjacent layers, such as difference, should be taken into account when selecting the polymerizable compound of each layer.

(A) Fluorine-free methacrylates listed above include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, tert-butyl methacrylate, benzyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate Latex, diphenylmethyl methacrylate, adamantyl methacrylate, isobornyl methacrylate, or norbornyl methacrylate, and (a) fluorine free acrylates are methyl acrylate, ethyl acrylate, tert- Butyl acrylate or phenyl acrylate.

(B) Fluorinated (meth) acrylates listed above include 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,3 , 3,3-pentafluoropropyl methacrylate, 1-trifluoromethyl-2,2,2-trifluoroethyl methacrylate, 2,2,3,3,4,4,5,5- Octafluoropentyl methacrylate, or 2,2,3,3,4,4, -hexafluorobutyl methacrylate.

The (c) styrene compound listed above may be styrene, alpha-methylstyrene, chlorostyrene, or bromostyrene, and (d) the vinyl ester is vinyl acetate, vinyl benzoate, vinyl phenylacetate, or vinyl chloroacetate. It may be. (e) The fluorine-containing main chain cyclic polymer forming monomer may be a monomer having a cyclic structure or a copolymer copolymerized to form a fluoro polymer having a cyclic structure in the amorphous main chain. The monomer has, for example, an aliphatic ring or a heterocyclic ring in the main chain as shown in polyperfluorobutanyl vinyl ether (known as CYTOP (registered trademark)), Japanese Patent Application Laid-Open No. 8-334634. A monomer which forms a polymer, or the monomer shown in Unexamined-Japanese-Patent No. 2004-186199. However, the selection of the polymerizable compound is not limited to the above. In addition, the type and amount of the polymerizable compound should be determined such that the polymer or copolymer formed can have a desired refractive index distribution as the light transmission medium.

In addition to those listed above, the polymer for the first member 12 is methyl methacrylate (MMA), trifluoroethyl methacrylate (3FM), hexafluoroisopropyl methacrylate, pentafluorophenyl meta It may be a copolymer with one of methacrylate and fluoro (meth) acrylate, or alternatively (meth) acrylate having a branched structure such as MMA and tert-butyl methacrylate, or isobornyl methacrylate It may be a copolymer with any one of cycloaliphatic (meth) acrylates such as late, norbornyl methacrylate and tricyclodecanyl methacrylate. Also for this purpose, polycarbonate (PC), norbornene-type resins (e.g., ZEONEX (registered trademark, manufactured by ZEON corporation)), functional norbornene-type resins (e.g., ARTON (registered trademark) , JSR)), a fluorine polymer (eg polytetrafluoroethylene (PTFE)), or polyvinylidene fluoride (PVDF). It is also possible to use fluorocopolymers (eg PVDF-based copolymers), tetrafluoroethylene perfluoro (alkyl vinyl ether (PFA)) random copolymers, or chlorotrifluoroethylene (CTFE) copolymers. It is possible.

When hydrogen atom (H) is included in the polymer, it should preferably be substituted with deuterium atom (D). This substitution reduces transmission losses, especially in the near infrared spectrum.

If optical fiber 19 is used in near infrared applications, any C-H bonds in the polymer can cause transmission loss. Therefore, as described in Japanese Patent No. 3333322 and Japanese Unexamined Patent Publication No. 2003-192708, it is preferable to replace the hydrogen atom at the C-H bond in the polymer with deuterium atom or fluorine. The polymer serves to move the transmission loss region to the long wavelength region, thereby reducing the loss of transmission signal light. Preferred polymers of this type are, for example, deuterated polymethyl methacrylate (PMMA-d8), polytrifluoroethyl methacrylate (P3FMA), and polyhexafluoroisopropyl-2-fluoroacrylics. Rate (HFIP2-FA). In addition, for better transparency of the formed polymer, impurities and foreign matters that may cause light diffusion must be removed from the polymerizable compound in advance.

The second member 16 will have a change in refractive index or refractive index distribution along its radial direction, for example, by one of the following two methods. The first method is to copolymerize two kinds of polymerizable compounds for two monopolymers having different refractive indices at different mixing ratios for different layers. An increase in the amount of the polymerizable compound for monopolymer having a high refractive index causes the formed copolymer to exhibit a high refractive index. Thus, the copolymer formed consists of several layers with different refractive indices. In this way, the layer of copolymer comprises a component having a general structural unit. This increases the affinity between the layers and minimizes irregularities at the interface. The second method is to mix the polymerizable compound for each layer with a refractive index regulator having a different refractive index than the polymerizable compound at different mixing ratios for the different layers. Adding more reagents to the inner layer gives the same refractive index distribution as in the first method. The refractive index regulator is described later in detail.

Preferred polymeric compounds for the first method are, for example, 2,2,2-trifluoromethyl methacrylate (3FMd7) forming a polymer having a refractive index of 1.41 and deuterated penta forming a polymer having a refractive index of 1.49. Fluorophenyl methacrylate (PFPMAd5). In the use of 3FMd7 and PFPMAd5, some of the hydrogen atoms are replaced by deuterium atoms to reduce transmission loss. Therefore, as mentioned above, it is preferable to select a polymeric compound so that the 2nd member 16 may consist of a polymer which has an amorphous part.

A polymerization initiator is used in the polymerization step 38. Preferably, the polymerization initiator should be one that forms a radical. The polymerization initiator and the polymerization reaction temperature are determined to satisfy the following formula (1):

TE2-20 ≤ TE1 ≤ TE2 + 25 ... (1)

In the formula, TE1 is a polymerization reaction temperature (° C), and TE2 is a 10 hour half-life temperature (° C) of the polymerization initiator.

Under the conditions for satisfying formula (1), the polymerization reaction proceeds effectively and efficiently. Therefore, productivity of the preform 11 is remarkably improved, and foaming is prevented in the stretching process 20.

Preferably, formula (1) is TE2 <TEl <TE2 + 20, more preferably TE2 <TEl <TE2 + 10. If several types of polymerization initiators are used, the lowest of those 10 hour half-life temperatures should be used as TE2.

The polymerization initiator is, for example, benzoyl peroxide (BPO), tert-butylperoxy-2-ethylhexanate (PBO), di-tert-butylperoxide (PBD), tert-butylperoxyisopropyl carbonate ( PBI), and one or a mixture of peroxide compounds such as n-butyl-4,4-bis (tert-butylperoxy) valerate (PHV). Alternatively, the polymerization initiator may be 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile) , 2,2'-azobis (2-methylpropane), 2,2'-azobis (2-methylbutane), 2,2'-azobis (2-methylpentane), 2,2'-azobis (2,3-dimethylbutane), 2,2'-azobis (2-methylhexane), 2,2'-azobis (2,4-dimethylpentane), 2,2'-azobis (2,3 , 3-trimethylbutane), 2,2'-azobis (2,4,4-trimethylpentane), 3,3'-azobis (3-methylpentane), 3,3'-azobis (3-methyl Hexane), 3,3'-azobis (3,4-dimethylpentane), 3,3'-azobis (3-ethylpentane), dimethyl-2,2'-azobis (2-methylpropionate) And azo compounds such as diethyl-2,2'-azobis (2-methylpropionate) and di-tert-butyl-2,2'-azobis (2-methylpropionate).

As described in JP-A-2003-192714 and 2003-246813, in addition to the above compounds, azo compounds without a nitrile group are also preferable. Azo compounds may generally be the preferred polymerization initiators for (meth) acrylic ester monomers, but if they contain nitrile groups, they may be deeply colored by heat to provide little light transmission properties required for optical members such as optical fibers. This is especially noticeable when mercaptans are used as chain transfer agents. Thus, an azo compound without a nitrile group is used, and an uncolored optical member having excellent light transmission characteristics can be produced. Preferred azo compounds without a nitrile group are represented by the following general formula (2).

[Formula 2]

In the formula (2), the symbols R ¹ , R ² , and R ³ represent an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 1 to 6 carbon atoms, -COOR ⁴ , or -CONR ⁵ R ⁶ . R ⁴ represents an alkyl group having 1 to 5 carbon atoms, and R ⁵ and R ⁶ represent an alkyl group having 1 to 9 carbon atoms or a cycloalkyl group having 3 to 6 carbon atoms. R ⁵ and R ⁶ may be linked to form a ring. The alkyl group represented by R ¹ and R ² may have a straight or branched chain. The alkyl group is, for example, a methyl group, an ethyl group, an n-propyl group, a tert-butyl group, an n-pentyl group, or a neopentyl group, and more preferably, a methyl group, tert-butyl group, or neopentyl group. The cycloalkyl group represented by R ¹ to R ³ , R ⁵ and R ⁶ may preferably be a cyclohexyl group.

Azo compounds represented by the formula (2) include 2,2'-azobis (2-methylpropane), 2,2'-azobis (2-methylbutane), 2,2'-azobis (2-methylpentane ), 2,2'-azobis (2,3-dimethylbutane), 2,2'-azobis (2-methylhexane), 2,2'-azobis (2,4-dimethylpentane), 2, 2'-azobis (2,3,3-trimethylbutane), 2,2'-azobis (2,4,4-trimethylpentane), 3,3'-azobis (3-methylpentane), 3, 3'-azobis (3-methylhexane), 3,3'-azobis (3,4-dimethylpentane), 3,3'-azobis (3-ethylpentane), dimethyl-2,2'-azo Bis (2-methylpropionate), diethyl-2,2'-azobis (2-methylpropionate), or di-tert-butyl-2,2'-azobis (2-methylpropionate May be It is noted that the polymerization initiator is not limited to the compound, and two or more kinds of the compound may be used together.

In order to control the degree of polymerization, a chain transfer agent may be added. In this case, the kind of chain transfer agent should be determined according to the kind of polymerizable compound. The chain transfer coefficient of the chain transfer agent for the polymerizable compound comes from, for example, "Polymer Handbook, 3rd Edition" (J. BRANDRUP & E.H. IMMERGUT EDIT, JOHN WILEY & SON). Alternatively, the chain transfer coefficient can be calculated through the experiment described in "Experimental Method of Polymer" (Takayuki Ohtsu and Masayoshi Kinoshita, edited by Kagakudojin, 1972).

Preferred chain transfer agents are alkyl mercaptans (e.g., n-butyl mercaptan, n-pentyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, or tert-dodecyl mercaptan) or thiophenols ( Thiophenol, m-bromothiophenol, p-bromothiophenol, m-toluenethiol or p-toluenethiol). More preferred are alkyl mercaptans such as n-octyl mercaptan, n-lauryl mercaptan, or tert-dodecyl mercaptan. It is also possible to use chain transfer agents in which the hydrogen atoms at the C-H bonds can be substituted with deuterium atoms or fluorine atoms. It is noted that the chain transfer agent is not limited to the above, and two or more kinds of chain transfer agents may be mixed.

If necessary, the non-polymerizable compound is preferably a refractive index regulator. The amount of the refractive index regulator is preferably 0.01% by weight to 25% by weight, more preferably 1% by weight to 20% by weight relative to the main component of the second member 16. Adjusting the amount of reagent in this manner facilitates the formation of the refractive index distribution described above.

The refractive index regulator should exhibit at least one of the following properties; High refractive index, large molecular volume, independent of polymerization reaction of polymerizable compound, low molecular weight compound which can diffuse at constant rate in molten polymer. Note that the refractive index regulator is not limited to monomers, and may be oligomers (including dimers and trimers).

Nonpolymerizable compounds for the refractive index regulators are, for example, benzyl benzoate (BEN), diphenyl sulfide (DPS), triphenyl phosphate (TPP), benzyl phthalate-n-butyl (BBP), diphenyl phthalate (DPP) , Diphenyl (DP), diphenylmethane (DPM), tricresyl phosphate (TCP), or diphenyl sulfoxide (DPSO). Especially preferred of these are BEN, DPS, TPP, or DPSO. Such a refractive index regulator is added to the material of the second member 16, and the concentration of the reagent is controlled for each layer. For this reason, each of the first layers 21 to n-th layer 24 is adjusted to a desired refractive index value.

The amount of the polymerization initiator and the chain transfer agent is determined depending on the kind of the polymerizable compound and other factors. The addition amount of the polymerization initiator is preferably 0.005 mol% to 0.5 mol%, more preferably 0.010 mol% to 0.1 mol% with respect to each polymerizable compound of the layers 21 to 24. In addition, the amount of the chain transfer agent added is preferably 0.005 mol% to 0.5 mol%, more preferably 0.010 mol% to 0.1 mol% with respect to each polymerizable compound of the layers 21 to 24.

Each of the layers 21-24 may include other additives only to the extent that their light transmission properties are maintained. For example, stabilizers may be added for better weather resistance and durability.

In addition, induced emission compounds may be added for the amplification of optical signals. Compounds of this kind excite signal light whose intensity decreases during transmission, thereby helping to extend the transmission distance. Thus, together with the additive, an optical member may be used, for example, as an optical fiber amplifier in an optical transmission link.

Hereinafter, the formation method of the 2nd member 16 is demonstrated. 3 shows a polymerization vessel 60 used in the production of the preform 11. The polymerization vessel 60 is made of SUS (Steel Use Stainless), and includes a cylindrical vessel body 60a and a pair of vessel lids 60b at both ends of the vessel body 60a. The first member 12 is introduced into the polymerization vessel 60. The inner diameter of the polymerization vessel 60 is slightly larger than the outer diameter of the first member 12, and the rotation of the polymerization vessel 60 can rotate the first member 12.

First, the 1st member 12 previously formed by the commercial melt-extrusion molding machine is thrown into the polymerization container 60, and one end of the 1st member 12 is closed with the plug 61. As shown in FIG. The plug 61 is formed of a material such as polytetrafluoroethylene (PTFE), which is hardly dissolved by the components of the first to nth layers 21 to 24.

Next, the first layer raw material 21a is supplied to the hollow portion of the first member 12. The other end of the first member 12 is blocked by a plug 61, and the container lid 60b is disposed at both ends of the container body 60a. The polymerization vessel 60 is then rotated in the rotary polymerization apparatus 71 shown in FIG. 4 to polymerize the first layer raw material 21a and form the first layer 21. In the present invention, the first member support element can be provided on the inner wall of the polymerization vessel 60, so that the first member 12 subsequently follows the rotation of the polymerization vessel 60. In addition, the first member 12 and the plug 61 can be used as the polymerization vessel 60.

As shown in FIG. 4, the rotary polymerization apparatus 71 controls the internal temperature of the main frame 72, the rotating member 73 in the main frame 72, the drive unit 76, and the main frame 72. It includes a thermostat (77).

The rotating members 73 are circular cylinders extending horizontally and are arranged parallel to each other so that at least one first member 12 can be supported by two adjacent rotating members 73. Each rotating member 73 is rotatably attached to one end of the side wall of the main frame 72 and is independently rotated by the drive unit 76. This rotation is controlled by a controller (not shown) of the drive unit 76.

As shown in FIG. 5, the polymerization vessel 60 is disposed on a groove defined by the surfaces of two adjacent rotating members 73. When the rotating member 73 is rotated about the rotation axis 73a, the polymerization vessel 60 is accompanied by rotation, whereby the polymerizable compound is polymerized. Note that the rotation system is not limited to this embodiment using the surface drive system for rotating the polymerization vessel 60.

A magnet 60c is provided in the container lid 60b across the polymerization vessel 60. In addition, a magnet 75 is provided below and between two adjacent rotating members 73. These magnets serve to prevent the polymerization vessel 60 from bouncing or floating on the rotating member 73 during rotation. However, it is also possible to use other methods to prevent bouncing of the polymerization vessel 60. For example, an additional rotating member similar to the rotating member 73 can be provided to hold the polymerization vessel 60 down. Alternatively, the holding means may be provided above the polymerization vessel 60. By leveling the long side of the first member 12 in this manner, the first layer 21 is formed over the entire inner surface of the first member 12. Note that the first member 12 is disposed on the side that is substantially horizontally long with respect to the ground, and the first layer 21 can likewise be formed. The allowable angle of the axis of rotation is within about 5 degrees with respect to the ground.

Optionally, prior to the polymerization step, the polymerizable compound may be pre-polymerized with the first member 12 upright. In this case, it is preferable to rotate the first member 12 by the rotation mechanism.

Preferably, the polymerizable compound and various additives may be filtered and distilled in advance to remove potential polymerization inhibitors such as moisture and impurities. More preferably, in order to remove the dissolved gas and the volatile substance, the first layer raw material 21a which is a mixture of the polymerizable compound and the additive may be treated by ultrasonic processing. Optionally, the first member 12 and the first layer raw material 21a may be subjected to a reduced pressure treatment with a known pressure reduction device before and / or after the first layer forming process 31.

The first member 12 having the first layer 21 formed therein is removed from the rotary polymerization apparatus 71 and heated in a general heating apparatus such as a thermostat oven for a certain period of time.

The polymerization vessel 60 with the first layer 21 is still used to form each of the second to nth layers. FIG. 6: shows sectional drawing of the polymerization container 60 at the start of a 2nd layer formation process, and the 2nd layer raw material 22a is deposited in a hollow part.

The reaction time of the polymerization step 38 (see FIG. 1) to the first layer 21 is preferably 0.5 hour to 5 hours, and the second layer raw material 22a is preferably as soon as the polymerization step 38 is completed. Should be introduced. This approach ensures sufficient polymerization reactivity and little unreacted polymerizable compound remains in the first layer 21. Thus, foaming in the stretching process 20 (see FIG. 1) is prevented, and the optical fiber 19 having the desired refractive index distribution can be efficiently produced. In practice, a reaction time of less than 0.5 hours results in insufficient polymerization reactivity, leaving many polymerizable compounds. On the contrary, reaction time of more than 5 hours takes too much time in the formation process of each layer, and cannot improve productivity.

The polymerization vessel 60 is then disposed in the rotary polymerization apparatus 71 and rotated about the center of the circular cross section for the polymerization of the second layer raw material 22a. Optionally, the interior of the polymerization vessel 60 may be depressurized by a known depressurization device before and / or after raw material feed.

In the initial stage of the polymerization reaction of the second layer raw material 22a, the inner wall of the first layer 21 is swollen by the polymerizable compound of the second layer to form a swelling layer. Being a gel layer, this swelling layer provides the so-called gel effect of accelerating the polymerization reaction. Thus, the term rotary gel polymerization process is used in a polymerization process in which a polymerizable compound is fed into a cylindrical polymer, rotated to form a swelling layer to accelerate the polymerization reaction. What is important in this polymerization process is to keep the long side of the cylindrical member parallel to the ground, as in the embodiment of the present invention.

It is desirable to control the rate of the polymerization reaction. For example, the reaction rate is controlled such that the conversion rate of the polymerizable compound is 5% to 90% per hour. More preferably, the conversion rate is 10 to 85% per hour, most preferably 20 to 80% per hour. The reaction rate can be controlled by adjusting the type and amount of the polymerization initiator and the polymerization temperature. Note that the conversion is measured through any general method such as, for example, visual evaluation based on a predetermined relationship between the results of quantitative analysis by gas chromatography of the remaining polymerizable compound and the results of visual observation of the reaction product. The conversion rate may also be controlled by adjusting the rotational speed of the rotary polymerization apparatus 71.

Through the above process, the second member 16 composed of the first to nth layers 21 to 24 is formed in the first member 12. Note that the cylindrical first member 12 and the second member 16 may be formed separately. In this case, the second member 16 is subsequently inserted into the hollow portion of the first member 12 to obtain the preform 11.

In the heating process 18 (see FIG. 1), the preform 11 is heated under reduced air pressure. If present, the unreacted polymerizable compound remaining in the preform 11 is removed by this process. While this is carried out under fixed conditions, the heating process 18 can preferably be carried out under gradually changing conditions. Such changing conditions provide the optical fiber 19 with better optical properties.

In this embodiment, the heating process 18 is divided into two stages: a first heating step to reduce the non-uniform density in the polymer, and a second heating step to remove the residue after the first heating step. In the first heating step, the preform 11 is heated for 24 to 72 hours under normal air pressure. The heating temperature in this step is determined according to the glass transition temperature Tg of the second member 16, namely the light guide portion. If the layers of the second member 16 have different glass transition temperatures, the heating temperature is based on the highest glass transition temperature. For example, when the highest glass transition temperature of the polymer of the second member 16 is 90 ° C, the heating temperature is preferably 90 to 140 ° C. The non-uniform density in the light guide polymer is reduced at this stage, so scattering losses are reduced. In the second heating step, the preform 11 is heated at a constant temperature of (Tg-10) ° C or more and less than Tg under air pressure reduced by 0.05 MPa to 0.1 MPa with respect to atmospheric pressure. Preferably, the heating temperature is kept constant at (Tg-8) ° C or more and less than Tg, more preferably at (Tg-5) ° C or more and less than Tg. In addition, the second heating step may preferably last for 24 to 100 hours. This step effectively removes the unreacted polymerizable compound from the preform 11 without reducing productivity, and also prevents deformation of the preform 11.

If the second heating step lasts less than 24 hours, the unreacted polymerizable compound may not be sufficiently removed. On the other hand, the second heating step exceeding 100 hours degrades the polymer and leads to transmission loss of the formed medium. The air pressure is reduced in at least the first or second heating step, preferably in the second heating step. Optionally, an additional heating step can follow the first and second heating steps.

When the heating temperature in the second heating step is less than (Tg-10) 占 폚, the unreacted polymerizable compound and the low boiling point impurity may not be sufficiently removed. On the other hand, the heating temperature of Tg or more deforms the preform 11. In the air pressure, a reduction of 0.1 MPa or more to atmospheric pressure is practically impossible, while a reduction of less than 0.05 MPa gives only a small effect to the preform 11.

Melt-stretching of the preform 11 under these conditions makes it possible to produce the optical fiber 19 having a desired diameter (for example, 200 μm to 1000 μm). The stretching method of the preform 11 is selected from conventional techniques, and an exemplary method is described in Japanese Patent Laid-Open No. 07-234322.

The optical fiber 19 may be a graded index type or a step-index type.

Higher flexibility and weather resistance, prevention of functional degradation caused by moisture absorption, higher tensile strength, stamping resistance, resistance to flame, protection from chemical reagents, protection from external light, and higher commerciality such as coloring For various purposes for value, the optical fibers 19 are wrapped with a first covering layer and become plastic optical cords (hereinafter optical cords). The first covering layer is single layer or multilayer.

As a result, the optical cord is wrapped with the second covering layer and becomes a plastic optical cable. In the following part of the present specification, a single optical cord with a second covering layer is called a single fiber cable. On the other hand, the plurality of optical cords tied with the tension member and wrapped with the second covering layer are called multi-fiber cables.

Some single fiber cables can be made without the second covering layer, instead using the first covering layer as the sheath. In addition, the second covering layer has two types of covering schemes, a contact covering in which the covering layer contacts the surface of the optical cord (s), and a loose covering in which a gap is formed between the covering layer and the optical cord (s). Are classified. The loose covering entails the risk of allowing moisture entry into the gap from the terminal end of the optical cable, for example when the second covering layer is peeled off to attach to the connector. Thus, contact covering is rather preferred.

However, loose type covering may be beneficial in some cases because the loose covering layer can reduce strain on the optical cable, such as bending stress or heat. The inherent risk, ie moisture entry into the gap, is eliminated by filling the gap between the optical cord and the second covering layer with gel or powder. In addition, if the gel or powder is provided with heat resistance or mechanical strength, the optical fiber cable obtains a multifunctional covering layer. The gap is formed by controlling the position of the extruded nipple in the cross head die body and the air pressure in the lapping process. In addition, the depth of the gap is controlled by pressurization / decompression between the nipple and the die. It is possible to add some additives such as flame retardants, ultraviolet absorbers, antioxidants, shading agents, and lubricants to the first and second covering layers to such an extent that the light transmission properties are not affected.

As the flame retardant, halogen-containing or phosphorus-containing agents such as bromine may be used, but recently popular flame retardants are metal hydroxides such as aluminum hydroxide or magnesium hydroxide in view of the reduction of poison gas emission. Generally, metal hydroxides include crystallized water or such moisture. This moisture is introduced during the production of the metal hydroxide and cannot be completely removed. Therefore, the metal hydroxide should not be added to the first covering layer in direct contact with the optical fiber 19, but only to the outermost second covering layer.

Optionally, the optical cable may be covered with additional functional layers that provide various functions for the optical cable. The functional layer is, for example, a barrier layer that prevents moisture absorption of the optical fiber 19 and a moisture absorption layer that extracts moisture from the optical fiber 19. The hygroscopic layer is a hygroscopic tape or hygroscopic gel disposed within or between the protective layers.

Other functional layers are a flexible material layer for relieving banding stress, a foam material layer as an impact absorber against external stresses, and a reinforcing layer for improving rigidity. The covering layer may be formed of a thermoplastic resin comprising, for example, high elastic modulus fibers (so-called tensile fibers) and / or rigid wire rods such as metal wires. These materials improve the physical strength of optical cables.

Tensile fibers are, for example, aramid fibers, polyester fibers, or polyamide fibers. Metal wiring is stainless wiring, zinc alloy wiring, copper wiring, etc. Note that tensile fibers and metallization are not limited to these. In addition, the outer surface of the optical cable may be provided with a metal protective tube, support wiring for floating, and a mechanism for easy wiring.

The optical cable has various forms such as an assembly type in which optical cords are arranged in concentric circles, a tape type in which optical cords are arranged in parallel. In addition, these optical cables may be wrapped or bundled with a LAP sheath in the optical cable. The shape of the optical cable is determined by its purpose.

The optical cable formed from the preform 11 and the optical fiber 19 of the present invention is more resistant to misaligned coupling as compared with the prior art, and thus can be directly connected to each other. However, it is certainly desirable to have optical connectors at the ends of all optical cables for stable coupling. Any optical connector already made, PN type, SMA type, or SMI type, can be used for this purpose. Accordingly, the optical cable of the present invention comprises an optical signal processor having an optical component such as a light emitting element, a light receiving element, an optical switch, an optical isolator, an optical integrated circuit, and an optical transmitter / receiver module; It is suitably used together. In this case, the optical cable of the present invention may be combined with other optical fibers, optical cords, or optical cables, if necessary, and any general technique may be applied. For example, "'Basic and Practice of Plastic Optical Fiber' (published by NTS Inc.)", "Optical members can be Loaded on Printed Wiring Assembly, at Last 'in Nikkei Electronics, vol. Dec. 3, 2001, pp. The technique described in 110-127 "is used.

These techniques allow the optical cable of the present invention to be used for computer and digital device wiring, automotive and ship internal wiring, optical terminals and optical links between digital devices, or between houses, factories, offices, hospitals and schools. It can be used in various applications, such as optical links between digital devices, which are high-speed, high-capacity data communications including indoor or outdoor optical LANs, short-range optical transmission systems without the influence of electromagnetic waves, and the like.

In addition, the optical cable of the present invention may constitute an improved optical transmission system for multiplex signal communication when combined by: "'High-Uniformity Star Coupler Using Diffused Light Transmission' in IEICE TRANS. ELECTRON., VOL. E84-C, No. 3, MARCH 2001, pp. 339-344 "and" 'Interconnection in Technique of Optical Sheet Bath' in Journal of Japan Institute of Electronics Packaging., Vol. 3, No. 6, 2000, pp. 476-480 "; Arrangement of a light emitting element on a waveguide surface disclosed in Japanese Laid-Open Patent Publication No. 2003-152284; Optical buses disclosed in Japanese Patent Application Laid-open Nos. Hei 10-123350, 2002-90571, and 2001-290055; Optical branching / coupling apparatus disclosed in Japanese Unexamined Patent Publication Nos. 2001-74971, 2000-329962, 2001-74966, 2001-74968, 2001-318263, and 2001-311840 ; Optical star coupler disclosed in Japanese Laid-Open Patent Publication No. 2000-241655; Optical signal transmission devices and optical data bus systems disclosed in Japanese Unexamined Patent Publication Nos. 2002-62457, 2002-101044, and 2001-305395; An optical signal processor disclosed in Japanese Laid-Open Patent Publication No. 2002-23011; Optical signal cross connect system disclosed in Japanese Laid-Open Patent Publication No. 2001-86537; An optical transmission system disclosed in Japanese Laid-Open Patent Publication No. 2002-26815; Multifunctional systems disclosed in Japanese Patent Laid-Open Nos. 2001-339554 and 2001-339555; And various optical waveguides, optical branching devices, optical couplers, optical multiplexers and the like. In addition, the optical cables of the present invention are also applicable to the fields of lighting, energy transmission, lighting, lenses and sensors.

Example 1

According to the manufacturing process 10 of FIG. 1, the optical fiber 19 comprised from the 1st member 12 and 11 layers of the 2nd member 16 was manufactured. In particular, a PVDF tube with an internal diameter of 18.5 mm and a length of 27 cm, formed by melt-extrusion molding, was made into a container for the second member 16. The refractive index of PVDF was 1.41. The first layer raw material 21a was supplied to the hollow portion of the PVDF tube through a PTFE membrane-filter having a 0.2 탆 hole. Each of the raw materials for the first layer 21 to eleventh layer contained 3FMd7 and PFPMAd5 as the polymerizable compound. The amount (unit: ml) of the two in each layer is shown in Table 1 below, where 3FMd7 is called “a” and PFPMAd5 is called “b”. First, 3FMd7 and PFPMAd5 were mixed together, followed by addition of MAIB (dimethyl 2,2′-azobis (isobutyrate)) as a polymerization initiator and 3-ethyl mercaptopropionate as a chain transfer agent. The ratio of MAIB to the mixture of 3FMd7 and PFPMAd5 was 0.1 mol%, and the proportion of 3-ethyl mercaptopropionate was 0.5 mol%. The 10 hour half life temperature of the MAIB was 66 ° C.

Floor Supply order a
(Ml) b
(Ml) One One 21.7 4.6 2 2 7.6 2.0 3 3 6.7 2.1 4 4 5.8 2.1 5 5 5.0 2.1 6 6 4.3 2.0 7 7 3.7 1.8 8 8 3.1 1.6 9 9 2.5 1.4 10 10 2.0 1.1 11 11 1.5 0.8

The PVDF tube containing the first layer raw material 21a is placed in the container body 60a and rotated on its long side parallel to the ground for 3 hours at 2000 rpm at 70 ° C in the rotary polymerization apparatus 71. The polymerization vessel 60 was made of SUS. An isolated type thermocouple was installed near the polymerization vessel 60, in particular 1 cm to 2 cm further from the polymerization vessel 60, and the temperature of the polymerization vessel 60 was measured during rotation. This measurement was made to find the peak temperature (heat peak) of heat induced by the polymerization reaction. The thermal peak reaches 67 ° C. at about 1 hour and 20 minutes from the start of the polymerization. Thereafter, the first layer 21 was formed in the PVDF tube, and the conversion rate of the formed polymer was 90%.

The PVDF tube having the first layer 21 therein was removed from the polymerization vessel 60, and the second layer raw material 22a was supplied to the tube hollow portion. The same polymerization process as the first layer 21 was performed. In fact, the refractive index of the first layer 21 was 1.432. The third to eleventh layers were then formed in order under the same conditions as the polymerization reaction of the first layer 21. As shown in Table 1, the amount of raw material decreased as the layer approached the center of the cross section.

The PVDF tube with the second member 16 in its hollow portion was heated at 130 ° C. for 24 hours, and the second member was removed from the PVDF tube. Of all the layers, the eleventh layer had the highest glass transition temperature, which was 85 ° C. The second member 16 was subsequently heated at 80 ° C. for 72 hours under air pressure reduced by 0.09 MPa to atmospheric pressure.

The cylindrical first member 12 was formed of THV resin, DyneonTHV500G (manufactured by Sumitomo 3M Limited), and the second member 16 was inserted into the first member 12 to constitute the preform 11. The preform 11 was then drawn to air pressure in the reduced hollow part 27. There was no foaming during this stretching process, and no bubbles were found between the first member 12 and the second member 16 in the optical fiber 19 after the stretching process. This optical fiber 19 showed a transmission loss of 120 dB / km at the 650 nm wavelength and 100 dB / km at the 850 nm wavelength.

[Example 2]

Example 2 was prepared for comparison with Example 1. The manufacturing process of Example 2 was the same as the manufacturing process of Example 1, but the following condition change was introduced. First, the temperature in the polymerization step was adjusted to 40 ° C. for each layer. As a result, it took about 10 hours to form a single layer and 111 hours to form all 11 layers. That is, compared with Example 1, productivity fell severely. Second, the temperature in the polymerization step was adjusted to 95 ° C. for each layer. The formed optical fiber showed a transmission loss of 300 dB / km at a wavelength of 650 nm and 150 dB / km at a wavelength of 850 nm. Transmission loss was particularly noticeable in the short wavelength region compared to the optical fiber 19 of Example 1. Third, the heating process 18 was performed at the heating temperature of 50 degreeC. Bubbles were generated at the boundary of the first member and the second member during the stretching step, and the formed optical fibers had a non-uniform circular cross section with a nonuniform diameter at ± 100 μm of the desired diameter. The optical fiber has a transmission loss of 800dB / km at 650nm and 780dB / km at 850nm. Finally, the heating process 18 was performed at the heating temperature of 90 degreeC. The preform was so severely deformed that it could not produce optical fibers.

The present invention is preferably applied to optical transmission, lighting, energy transmission, lighting, sensors, uneven lenses and the like.

Claims (7)

delete delete delete delete A supplying step of supplying the polymerizable compound and the polymerization initiator to the tubular vessel; A polymerization step of rotating the tubular vessel around the center of the circular cross section of the tubular vessel until the polymerizable compound is polymerized, wherein TE2-20 ≦ TE1 ≦ TE2 + 25, wherein TE2 (° C.) The polymerization step carried out at a reaction temperature TE1 (° C.) determined to satisfy the equation represented by 10 hours half-life temperature); A multilayer optical transmission medium forming step of performing the supplying step and the polymerization step alternately several times to form a multilayer optical transmission medium composed of a plurality of concentric layers in the tubular container; A first heating step of heating the multilayer optical transmission medium for 24 to 72 hours; Under an air pressure reduced by 0.05 MPa to 0.1 MPa relative to atmospheric pressure, when Tg is the glass transition temperature of the polymer formed in the polymerization step, (Tg-10) ° C. or more and less than Tg for 24 to 100 hours after the first heating step A second heating step of heating the multilayer light transmission medium at a heating temperature of; And And a drawing step of heating and stretching the multilayer optical transmission medium after the second heating step. 6. The method of claim 5, The said heating temperature in a said 2nd heating step is the manufacturing method of the plastic optical fiber which is (Tg-8) degreeC or more and less than Tg. 6. The method of claim 5, The said heating temperature in a said 2nd heating step is a manufacturing method of the plastic optical fiber which is (Tg-5) degreeC or more and less than Tg.

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