JP2007108271A - Method for manufacturing plastic optical member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and inexpensively manufacture plastic optical members having various types and kinds of cross-sectional forms with high accuracy. <P>SOLUTION: A PMMA (polymethyl methacrylate) rod molded by melt extrusion using PMMA is prepared as a core portion 25a, and a hollow clad pipe made of PVDF (polyvinylidene fluoride) is prepared as a clad portion 26a. The PMMA rod is inserted into the clad pipe to form a core portion 15. A shell portion 16 having a square cross-sectional form and a fitting hole 27 in a similar form to the cross-sectional form of the core portion 15a is formed by melt extrusion molding using PMMA. The core portion 15 is fitted to the shell portion 16 to obtain a preform 12. After the preform 12 is subjected to vacuum treatment while heating, the preform 12 is heated and stretched to obtain an optical member 10 having a cross-sectional form similar to the cross-sectional form of the preform 12. Thus, the obtained optical member 10 has a square cross-sectional form. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a plastic optical member.

  Conventionally, as an optical member for propagating light, it has a high hardness and is chemically stable, has a low transmission loss, and further has advantages such as excellent transparency and moldability. Is used. Examples of the quartz-based optical member include an optical fiber, an optical waveguide, a lens, and an electronic component depending on the use and shape. Recently, however, plastic optical members have been attracting attention because they have advantages such as excellent workability and transparency comparable to quartz optical members, and can be reduced in weight. This plastic optical member has the disadvantage that the transmission loss is slightly larger than that of the quartz-based material because all of the material is a polymer, but in addition to the above-mentioned advantages, it exhibits good flexibility and is also more flexible than the quartz-based material. Since it has an advantage that a large aperture is possible, use as an optical transmission body for a short distance in which the magnitude of transmission loss is not a serious problem is being studied (see, for example, Patent Document 1). ).

  The plastic optical member includes a core made of plastic and serving as an optical transmission line (sometimes referred to as a core portion), and a clad made of plastic having a lower refractive index than the core (sometimes referred to as a clad portion). Yes. In the following description, a member including a core is referred to as a core portion, and a member that is disposed on the outer periphery of the core portion and is intended to improve thermal damage, water resistance, and the like on the core portion is referred to as an outer shell portion. . The outer shell includes a protective layer that protects the cladding and the core.

  The core, particularly the core, has a refractive index distribution in which the refractive index gradually changes from the center of the diameter toward the outside. As described above, the plastic optical member is classified into a graded index (GI) type, a step index (SI) type, a multi-step index (MI) type, and the like depending on a difference in refractive index distribution. In the above, the GI type plastic optical member has a refractive index that continuously decreases from the center of the diameter toward the outside, and the MSI type plastic optical member has a refractive index that increases from the center of the diameter toward the outside. It will be lowered. In the SI type plastic optical member, the refractive index changes stepwise at the boundary between the core and the clad.

  Regardless of the difference in refractive index distribution, known methods for producing a plastic optical member include a melt spinning method, a melt extrusion method, and a polymerization method for obtaining a polymer from a monomer. And the cross-sectional shape in the radial direction of the plastic optical member manufactured by these methods is often circular. However, depending on the application, it may be desirable that the cross-sectional shape is not a circle but a rectangle or an ellipse. Moreover, regarding the usage form of the plastic optical member, usually, in the case of the use as an optical transmission body, it is often used with only one single core. However, in applications such as parallel signal transmission, image capture, and image output, a plurality of plastic optical members may be used in close array or in a cylindrical or prismatic shape.

As a method of forming an aggregate using a plurality of single-core optical members as described above, a method of thermocompression bonding in a state where a plurality of optical members are arranged in parallel (see, for example, Patent Document 2), photoresist or etching (See, for example, Patent Document 3) using an optical member, and further, a plurality of core parts are inserted into a clad part in which a plurality of hollow parts are formed in parallel to form an optical element having a multi-core structure. A method of manufacturing a member has been proposed (see, for example, Patent Document 4).
JP-A-61-130904 JP-A-6-317716 JP 2001-166165 A JP 2005-003899 A

  However, among the patent documents listed above, Patent Document 4 is a method for manufacturing a quartz optical member, and is not a description regarding a plastic optical member. In any of the above methods, there is a problem in that, when an optical member is manufactured, a special device is required for processing, resulting in an increase in equipment cost. In addition, when a processing apparatus is used corresponding to various optical members, the manufacturing time is increased and the manufacturing cost is increased. In addition, when an optical member having a desired cross section is formed as in Patent Document 2, it is difficult to ensure the accuracy because it requires very fine processing, and the manufacturing efficiency is reduced. Have the problem of

  An object of the present invention is to provide plastic optical members having various cross-sectional shapes at a low cost. Another object of the present invention is to provide a method capable of manufacturing the above plastic optical member with high accuracy.

  The method for producing a plastic optical member according to the present invention is a method for producing a plastic optical member by stretching an optical member preform. In the method for producing a plastic optical member, an optical member preform is formed by fitting a plurality of optical member preform pieces formed from a polymer. An optical member preform forming step for forming a plastic optical member, and a heat stretching step for heat stretching so that the cross-sectional shape of the plastic optical member is substantially similar to the cross-sectional shape of the optical member preform. To do.

  The optical member preform piece includes a core portion serving as an optical transmission path and an outer shell portion provided with a hollow fitting hole. In this optical member preform forming step, the fitting provided in the outer shell portion is provided. It is preferable to insert a core part into the hole. And it is preferable that the shape of the cross section of a plastic optical member is a figure which combined the polygon, the closed curve, the straight line, and the curve.

  The core part preferably includes a core part that becomes an optical transmission path. Moreover, it is preferable that this core part is formed by arranging a core part and a clad part having a lower refractive index than the core part around the core part. And it is preferable that an outer shell part contains at least 1 among the protective layers which protect a clad part and a core part. Further, the shape of the cross section of the core portion and the shape of the cross section of the fitting hole are substantially similar, and the clearance X (mm) of the gap formed when the core portion is fitted into the fitting hole However, it is preferable that the condition of 0 <X ≦ 8 is satisfied.

  It is preferable to heat stretch the optical member preform while reducing the gap. Furthermore, this outer shell part preferably has a plurality of fitting holes. The optical member preform is preferably an optical member preform aggregate formed by arranging single-core optical member preforms having a single-core structure. The optical member preform aggregate is preferably composed of an intermediate optical member preform formed by heating and stretching a single-core optical member preform. Adjacent single-core optical member preforms are preferably bonded together to form an optical member preform aggregate, and adjacent single-core optical member preforms are fused together to form an optical member preform aggregate. Is preferably formed.

  The single-core optical member preform is preferably fused before heating and stretching, and the single-core optical member preform is preferably fused by heating during the heating and stretching. The optical member preform aggregate preferably includes single-core optical member preforms having different shapes. And it is preferable that an optical member preform aggregate contains the single core optical member preform which shows a different optical characteristic.

  Moreover, this core part contains an acrylic polymer, and it is preferable that at least one of the core part and the outer shell part is a polymer containing a fluorine atom. The core preferably has a refractive index that gradually changes from the center toward the outside in the cross section.

  In the method for producing a plastic optical member of the present invention, first, after forming a core portion made of a polymer and an outer shell portion having a fitting hole into which the core portion is inserted, these are fitted to form an optical member preform. Therefore, optical member preforms having a wide variety of cross-sectional shapes can be obtained by combining them while changing the shapes of the core portion and outer shell portion to be fitted. In addition, the optical member preform is heated and stretched so that the outer shape of the cross section of the plastic optical member is substantially similar to the outer shape of the cross section of the optical member preform. A plastic optical member having a fine structure can be easily manufactured.

  Further, the cross-sectional shape of the core portion and the cross-sectional shape of the fitting hole are substantially similar, and the clearance X (mm) of the gap formed when these are fitted is set to 0 < Since X ≦ 8, the contact surfaces of the members can be easily fitted without being damaged. When the optical member preform has voids, the voids are heated and stretched while reducing the pressure, so that the optical member can be obtained without foaming inside.

  Further, as the optical member preform, the single-core optical member preform having a single-core structure is assembled to form an optical member preform assembly having a multi-core structure. The range of selection of the outer shape is further expanded, and as a result, plastic optical members having various cross-sectional shapes are obtained. Such a multi-core optical member preform can be easily formed by using an outer shell portion having a plurality of fitting holes. In addition, since the optical member preform or the optical member preform assembly is formed using an intermediate optical member preform formed by heating and stretching a single-core optical member preform, a more complicated cross section Even if it is a shape, a plastic optical member having a substantially similar cross-sectional shape can be obtained. In addition, since the single-core optical member preform includes different shapes and materials, it is possible to widen the variety of cross-sectional shapes and easily produce complex plastic optical members. can do. When arranging or bundling a plurality of single-core optical member preforms, use an adhesive, heat fusion by heat at the time of heat stretching, or fusion by heat fusion before heat stretching. Since the adhesiveness between the interfaces is improved, it is possible to perform heat stretching while preventing displacement between the single-core optical member preforms.

  In the present invention, the core includes a core serving as an optical transmission path and a hollow cladding having a lower refractive index than the core, and the cladding and the core are protected on the outer periphery of the core. Since the outer shell part including at least one of the protective layers to be formed is formed, plastic optical members such as plastic optical fiber (POF) and plastic optical waveguide having excellent heat resistance and durability can be easily formed. Can be manufactured. Furthermore, the core part contains an acrylic polymer, has a specific refractive index distribution as it goes from the center of the diameter to the outside, and the outer shell part is made of a polymer containing fluorine atoms. It is possible to manufacture a plastic optical member such as a GI type or an SI type that is excellent in transparency while having a low transmission loss.

  Hereinafter, the present invention will be described in detail. The preferred embodiment describes a preferred application example of the present invention, and does not limit the present invention.

  FIG. 1 shows a first manufacturing process 11 as a first embodiment according to the present invention. The first manufacturing process 11 includes a preform forming process 13 for manufacturing an optical member preform (hereinafter referred to as a preform) 12 and a heat stretching process 14 for heating and stretching the preform 12 to form the optical member 10. .

  First, the preform 12 is manufactured in the preform forming step 13. The preform 12 includes a core portion 15 and a hollow outer shell portion 16 positioned at the center of the diameter, and is formed by fitting each member. First, the core portion 15 is formed in the core portion forming step 17, and the outer shell portion 16 is formed in the outer shell portion forming step 18. Next, in the fitting step 19, the core portion 15 and the outer shell portion 16 are fitted to form the preform 12. Then, in the heat stretching step 14, the preform 12 obtained by fitting is heat stretched to produce the optical member 10 having a desired size.

  In the heating and stretching step 14, the preform 12 is placed in the heating furnace 20 as shown in FIG. Then, the preform 12 is heated by the heating furnace 20 to soften a part of the preform 12, and then drawing (stretching) is performed with the leading end 12 a of the softened portion as a starting point to obtain the optical member 10. Although this softening temperature is not specifically limited, It is preferable that it is a temperature of 80-500 degreeC, More preferably, it is 180-240 degreeC, Most preferably, it is 190-220 degreeC. Then, the wire diameter monitor 21 is wound around the core material 22 of a winding device (not shown) while constantly checking the wire diameter of the drawn optical member 10. As described above, a roll-shaped optical member product can be obtained. When the preform 12 is drawn, a wire diameter monitor 21 is provided to monitor the outer diameter of the optical member 10 as in this embodiment, and the inside of the heating furnace 20 is monitored according to the monitoring result. The outer diameter of the optical member 10 is always kept constant by appropriately adjusting the position of the preform 12, the temperature of the heating furnace 20, the winding speed of the winding device, and the like.

  The softening by heat stretching in the present invention refers to a state in which a substantially similar cross section is obtained when a non-circular preform is heat stretched, and melting by heat stretching in the present invention is When a non-circular preform is heated and stretched, a substantially similar shape is not maintained and a cross-section such as a substantially circular shape is obtained. Since the temperature at which the preform softens depends on the temperature characteristics of the polymer and cannot be specified unconditionally, the temperature at which the preform softens at the time of heating and stretching is determined for each polymer by experiments, etc. Heat stretching is performed. (Hereafter, delete)

  Thereby, the optical member 10 having a shape substantially similar to the cross section of the preform 12 is obtained. In this case, if the optical member 10 is obtained by continuously softening a part of the preform 12, it is advantageous from the viewpoint of reducing the production cost. Further, after the optical member 10 is formed, a protective film may be formed by covering the outer peripheral surface with a resin. The protective film by this coating may be formed by irradiating radiation after application of the radiation curable resin, or may be formed by extrusion molding of a thermoplastic resin. Examples of the optical member 10 manufactured by the above method include a rectangular POF and an optical transmission body. In addition, when forming a protective film, you may carry out as a separate line from the manufacturing process of an optical member, and you may incorporate in the manufacturing process of an optical member by performing after a heating extending process.

  In FIG. 3, the schematic of an example explaining the 1st manufacturing process 11 is shown. As shown in FIG. 3A, the core part 15 has a core part 25a and a clad 26a. The core portion 25a is a member serving as a light transmission path, and the clad portion 26a is a hollow member that has a lower refractive index than the core portion 25a and totally reflects light at the interface with the core portion 25a. In the present embodiment, the refractive index distribution of the core portion 25a is adjusted so that the refractive index gradually increases from the center of the diameter toward the outside. The core 15 having such a refractive index distribution is configured in the same manner as a preform for a GI type plastic optical fiber (POF).

  The manufacturing method of the core part 25a and the clad | crud 26a is not specifically limited. For example, there is a method of radical polymerization after injecting PMMA for forming the core portion 25a into a clad pipe formed by melt extrusion molding using PVDF, and this method is applied in this embodiment. In addition, the core part 15 provided with the clad part 26a on the outer periphery of the core part 25a may be formed by using a melt extrusion apparatus equipped with a composite type nozzle capable of co-extrusion. It should be noted that a desired refractive index distribution can be expressed by adding a refractive index adjusting agent to the polymer for forming the core portion 25a and adjusting the dispersion and concentration. Specific examples include a production method by radical polymerization described in Japanese Patent No. 3332922 and a melt extrusion method described in Japanese Patent Application No. 2004-354786, and these descriptions also apply to the present invention. Can do.

  As shown in FIG. 3A, the outer shell portion 16 is a member having a fitting hole 27. The manufacturing method of the outer shell part 16 is not particularly limited. For example, the outer shell part 16 may be formed by commercially available melt extrusion using a material for forming the outer shell part 16 (for example, PMMA or PVDF). In this embodiment, PMMA is used for melt extrusion molding. Moreover, the cross-sectional shape of the fitting hole 27 does not need to be circular, and may be appropriately selected from a polygon such as an ellipse or a rectangle, or a combination of a straight line, a curve, an arc, and an ellipse. good. However, the cross-sectional shape of the fitting hole 27 is substantially similar to the cross-sectional shape of the core portion 15. Thereby, when the core part 15 and the outer shell part 16 can be easily fitted, and the optical member 10 is used, inconsistency at the interface between the core part 15 and the outer shell part 16 is avoided. Can do.

  And the core part 15 is inserted in the fitting hole 27, and it mutually fits, and the preform 12 as shown in FIG.3 (B) is formed. At this time, the sizes of the core portion 15 and the fitting hole 27 are adjusted so that the gap 28 is formed during fitting. In the present invention, the clearance X (mm) of the air gap 28 satisfies 0 <X ≦ 8. As a result, the core portion 15 and the outer shell portion 16 can be easily fitted, and contact between the two members at the time of fitting (particularly contact at the interface) can be prevented. Suppresses the deterioration of characteristics. However, in the case of 8 <X, since the clearance is too large, when the optical member is used, the consistency between the core portion and the fitting portion may be lowered. In the present embodiment, the form in which the core portion 15 is fitted at substantially the center of the fitting hole 27 is shown, but the arrangement position is not particularly limited, and deviation may occur. In this case, the maximum value of the clearances of the gaps 28 to be formed is X, so that the above condition is satisfied.

  As shown in FIG. 3C, the optical member 10 formed by heating and stretching the preform 12 includes a core member 15a including a core 25b and a clad 26b, and an outer shell member 16a. The core 25b is formed by heating and stretching the core portion 25a, and the clad 26b is formed by heating and stretching the clad portion 26a. Therefore, the characteristics such as the refractive index distribution are substantially the same. The optical member 10 has a cross-sectional shape that is substantially similar to the shape of the cross-section of the preform 12. The draw ratio is not particularly limited, but the optical member 10 is preferably 10 to 500 times the preform 12.

  However, when the preform 12 is heated and stretched to obtain the optical member 10, the work is performed while the gap 28 is decompressed. Thereby, it can suppress that foaming arises inside the preform 12, and can obtain the optical member 10 with few defects. In addition, when performing pressure reduction, it is only necessary to work using a commercially available pressure reduction device while appropriately adjusting the degree of pressure reduction according to the state of the preform 12, and the device and pressure reduction conditions are not particularly limited. Absent.

  In addition, it is preferable to perform at least one of heat treatment and heat decompression treatment on the preform 12 before performing the heat stretching. Thereby, when the degree of polymerization of the members constituting the preform 12 is insufficient, the degree of polymerization can be improved and chemically stabilized, and the consistency at the interface can be improved. . Examples of the heat treatment include a method of heating the preform 12 so that the glass transition temperature Tg ± 40 ° C. of the main polymer. Moreover, as a heat | fever decompression process, the method of performing 0.1-2000 Pa pressure reduction with respect to the preform 12 with the pressure reduction apparatus under the said heating temperature is mentioned. However, the present invention is not particularly limited to these methods.

  In addition, before the preform 12 is heated and stretched, it is preferable that one of the end portions of the preform 12 is fixed. Thereby, the preform 12 can be extended without dropping the core portion 15 from the outer shell portion 16 or shifting the fitting position. However, the end part to be fixed is the end part that becomes the stretching direction at the time of heat stretching. In addition, after providing a fixing member in the fitting hole 27 by the side of a fixed end part, it is preferable to fix a desired end part so that the core part 15 may be inserted. Examples of the fixing member include a heat-resistant tape such as a commercially available polyimide tape and an adhesive such as a heat-resistant epoxy resin. The fixing member is not particularly limited, but it is preferable to select the fixing member in consideration of the affinity between the polymer material forming the preform 12 and the fixing member because excellent adhesiveness can be expressed at the interface. In addition to the above, a method of heat-sealing the fixed end portion side can also be preferably used. In this case, the core portion 15 and the outer shell portion 16 may be fused so as to close the gap 27 by heating the fixed end portion side with a heating device. The heating device is not particularly limited as long as the fixed end portion can be directly heated and fused. For example, a hot plate, an electric heater, etc. are mentioned.

  Further, as a method for fixing the desired end, as shown in FIG. 4, a method of providing a bottom portion made of solidified plastic on the fixed end can be preferably used. First, as shown in FIG. 4A, the plastic pellet is put into the fixed end portion 13a located on the extending direction side in the end portion of the fitting hole 13. Next, the fixed end portion 13 is partially heated with a heater or the like to make the plastic pellet into a molten plastic 29a, and then the core portion 15 is inserted into the fitting hole 27. Then, as time passes, as shown in FIG. 4 (B), the molten plastic 29a is cooled to become the solidified plastic 29b, so that the core 15 and the outer shell 16 are fixed by the fixed end 13a. .

  In this embodiment, although the cross section of the core part 15 and the outer shell part 16 showed the form which is circular, it is not specifically limited. The shape of the cross section is not only circular, but also non-circular, that is, a polygon, closed curve, formed by appropriately selecting and combining polygons such as ellipse, rectangle, etc., or straight lines and curves, arcs, ellipses, Examples include figures consisting of straight lines and curves. Thus, the preform 12 having various cross-sectional shapes can be formed by appropriately combining the cross-sectional shapes of the core portion 15 and the outer shell portion 16. By using such a preform 12, it is possible to manufacture a wide variety of optical members 10 that are substantially similar to the cross-sectional shape thereof.

  In addition, the manufacturing method of the core part 15 and the outer shell part 16 is not specifically limited, For example, the melt extrusion method etc. are mentioned. A melt-extrusion apparatus used for the melt-extrusion method has a composite spinning nozzle at its tip. Since various forms of nipples and dies constituting the composite spinning nozzle can be used, by changing the form of this composite spinning nozzle, cores or outer shells having various cross-sectional shapes can be formed. What is necessary is just to form. At this time, the cross section of the core portion or the outer shell portion can be made non-circular according to the form of the nipple or die.

  In addition, it is preferable that the melting temperature difference between the core portion 15 and the outer shell portion 16 is within 100 ° C. However, when the members constituting the preform 12 are the core portion 25a, the clad portion 26a, and the outer shell portion 16 as in this embodiment, the melting temperature difference for each member is within 100 ° C. To. Thus, if the melting temperature difference of each member is 100 ° C. or less, no stress is applied in the state in which the constituent resin is not softened when heating and stretching, and further, the core portion 15 and the outer shell portion The work can be performed without causing a thermal damage difference at 16.

  The outer shell part in the present invention refers to a member located in the outermost shell of the preform. Therefore, when the core part is only the core part, the clad part can be disposed as the outer shell part. However, in this case, after forming a clad portion having a fitting hole and having a lower refractive index than the core portion, the core portion and the clad portion may be fitted to form a preform.

  Further, in the present embodiment, the GI type in which the refractive index continuously decreases from the center of the diameter toward the outside is shown, but it is only necessary that the refractive index distribution gradually changes from the center of the diameter toward the outside. There is no particular limitation. In addition to the GI type, for example, there are an SI type in which the refractive index changes at the cladding interface, and an MSI type in which the refractive index gradually decreases from the center of the diameter toward the outside. In this embodiment, the refractive index distribution is expressed in the core portion. However, the present invention is not particularly limited, and the refractive index distribution is expressed in the entire core portion including the core portion and the cladding portion. Alternatively, the core portion may be made of PMMA without containing a refractive index adjusting agent as a core portion, a cladding portion made of PVDF, and an outer shell portion made of PMMA having the same refractive index as that of the core portion. After forming these, when these are fitted, a preform showing an SI type refractive index distribution may be formed. In addition, when forming a preform by using a plurality of members as described above and fitting them together, heat-stretching is performed in the heat-stretching step so that the interfaces of the respective members are heat-sealed at a time. Can be made.

  An outer shell portion provided with a plurality of fitting holes can also be applied to the present invention. FIG. 5 shows a schematic diagram of an example of an optical member using an outer shell portion provided with a plurality of fitting holes. As shown in FIG. 5A, the outer shell portion 30 has two fitting holes A31 and two fitting holes B32. Each fitting hole has a different size, and the outer cross-sectional shape of the outer shell portion 30 is a rectangle. As shown in FIG. 5B, the core portion A33 and the core portion B34 fitted to the outer shell portion 30 are substantially similar to the shape of the cross section of each corresponding fitting hole. The core part A33 corresponding to the fitting hole A31 includes a core part A33 and a clad part A33b. On the other hand, the core part B34 corresponding to the fitting hole B32 includes a core part B34a and a clad part B34b. And if core part A33 and core part B32 are inserted in the fitting hole corresponding to each, as shown in Drawing 5 (C), preform 35 in which space A36 and space B37 were formed can be obtained. .

  Then, the preform 35 is heated and stretched while decompressing each gap to obtain an optical member 38 as shown in FIG. Since the optical member 38 is drawn to have a small diameter, each gap disappears, and the core member A39, the core member B40, and the outer shell member 41 are in close contact with each other. In addition, when using the outer shell portion having a plurality of fitting holes as described above, the shape or size of the cross section of the outer shell portion is not particularly limited, and is circular, non-circular, that is, elliptical. The shape may be appropriately selected from a polygon such as a rectangle, or a combination of a straight line, a curve, an arc, and an ellipse. Further, the size, shape, number, and the like of the fitting holes provided in the outer shell portion may be appropriately adjusted so as to correspond to the shape of the core portion to be used and the desired number, and are not particularly limited.

  Hereinafter, an embodiment according to the present invention will be described with reference to manufacturing steps. Note that the manufacturing conditions according to the present invention described with reference to the first manufacturing process 11 are applied to second to fourth manufacturing processes to be described later, and description of related parts is omitted in each process.

  FIG. 6 shows a second manufacturing process 50 as a second embodiment according to the present invention. In the second embodiment, a preform assembly 52 is formed using a plurality of preform pieces 51 having a single core structure composed of a single core portion 60 and an outer shell portion 61, and then the preform assembly 52 is heated and stretched to form an optical member. 53 is manufactured. That is, the preform aggregate 52 plays a role as a preform. Therefore, the second manufacturing process 50 includes a preform forming process 55 including a preform assembly forming process 66 and a heat stretching process 56.

  The preform forming step 55 includes a core portion forming step 62, an outer shell portion forming step 63, a fitting step 65, and a preform assembly forming step 66. First, after forming the hollow core portion 60 in the core portion forming step 62, the outer shell portion 61 is formed in the outer shell portion forming step 63. The manufacturing method of the core part 60 and the outer shell part 61 should just use the same method as the 1st manufacturing process 11, and is not specifically limited. The core portion 60 includes a core portion serving as a light transmission path, and the outer shell portion 60 is either a clad portion disposed on the outer periphery of the core portion or a protective layer that protects the core portion 60. Including one. However, the outer shell part 61 shall have a fitting hole. This fitting hole is adjusted so that the outer diameter of the fitting portion is substantially similar to the outer shape of the core portion 60 and larger than that of the core portion 60.

  Next, in the fitting step 65, the preform 60 is formed by fitting the core 60 and the outer shell 61. The shape of the cross section of the preform piece 51 may be circular or non-circular. In the preform assembly forming step 66, a plurality of preform pieces 51 are arranged to form a preform assembly 52 having a desired cross-sectional structure. Further, the preform aggregate 52 is heated and stretched so that the shape of the cross section thereof is substantially similar to the shape of the cross section of the optical member 53. As described above, the optical member 53 having a desired cross-sectional shape and outer diameter can be obtained. Examples of the optical member 53 manufactured by this method include two-core high-speed serial transmission, multi-core parallel transmission, and image reading POF and plastic optical fiber arrays. Details of manufacturing conditions in the second manufacturing process 50 will be described later.

  FIG. 7 shows a third manufacturing process 70 as a third embodiment according to the present invention. In the third embodiment, the preform segment 71 is stretched to form an intermediate preform 72, and then a plurality of the preforms are used to form a preform aggregate 73. This preform aggregate 73 becomes a preform. Then, the optical member 74 is manufactured by heating and stretching the preform aggregate 73. Accordingly, the third manufacturing process 70 includes a preform forming process 75 including a first heat stretching process 83 for forming the intermediate preform 72 and a second heat stretching process 76.

  First, in the core portion forming step 80, a core portion 87 to be an optical transmission path is formed. At the same time, in the outer shell portion forming step 81, a hollow outer shell portion 88 which is disposed on the outer shell of the core portion 87 and has a fitting hole is formed. In addition, the manufacturing method of the core part 80 and the outer shell part 88 is not specifically limited, What is necessary is just to use the same thing as the method shown in the 1st manufacturing process 11. FIG. Next, in the fitting step 82, the core part 87 and the outer shell part 88 are fitted to form a preform piece 71.

  Next, in the first heat stretching step 83, the preform piece 71 is heated and softened, and then stretched to obtain an intermediate preform 72. Although the heating temperature in the 1st heating extending process 83 is not specifically limited, For example, when the core part 87 is a form which has the core part which consists of PMMA, and the clad part which consists of PVDF, 130- It is preferable to satisfy 250 ° C. Further, the draw ratio is not particularly limited, but is preferably 10 to 500 times that of the preform piece 71. Subsequently, in a preform assembly forming step 84, a plurality of intermediate preforms 72 are arranged in a desired structure to form a preform assembly 73. Then, in the second heat stretching step 76, the optical member 74 is manufactured by heat stretching the preform aggregate 73. The outer shape of the optical member 74 in the cross section is substantially similar to the cross section shape of the preform assembly 73. Examples of the optical member 74 manufactured as described above include a refractive index distribution type plastic lens obtained by cutting the optical member 74 into an appropriate length. Details of manufacturing conditions in the third manufacturing process 70 will be described later.

  The shape in the cross section of the core part 87 and the outer shell part 88 is not specifically limited, In addition to a circular shape, a polygon such as a triangle, a rectangle, a pentagon, a hexagon, or an oval that is non-circular, The shape may be any combination of a straight line, a curved line, and an arc. Further, the number, shape, size, etc. of the intermediate preform 72 constituting the preform aggregate are not particularly limited.

  FIG. 8 shows a fourth manufacturing process 90 as a fourth embodiment according to the present invention. In the fourth embodiment, the preform piece 91 is heated and stretched to form the first intermediate preform 92, and then a process of fitting and heating and stretching the member that becomes the outer shell portion around the outer periphery is performed, A preform 93 having an n-layer outer shell is formed. Then, the optical member 94 is manufactured by heating and stretching the preform 93. Accordingly, the fourth manufacturing process 90 includes a preform forming process 95 including a first heat stretching process 101 for forming the first intermediate preform 92, and a heat stretching process 96.

  First, the preform piece 91 is formed in the preform piece forming step 100. As shown in the second manufacturing process 50 and the third manufacturing process 70, the preform piece 91 is formed by forming a core part and an outer shell part having a fitting hole, and then inserting the core part into the fitting hole. Are formed by fitting each other. In addition, the manufacturing method of a core part and an outer shell part should just use the same thing as the method shown in the 1st manufacturing process 11. FIG. The fitting process here is referred to as a first fitting process (not shown). Next, in the first heating and stretching step 101, the preform piece 91 is heated and stretched to form a first intermediate preform 92 having a desired size. The heating temperature and the stretching ratio in the first heating and stretching step 101 are the same as those in the first stretching step 83 shown in FIG.

  In the 2nd fitting process 102, the hollow 2nd outer shell part 110 and the 1st intermediate body preform 92 which were formed previously are fitted, and a fitting body is formed. Next, in the second heating and stretching step 103, the second intermediate preform 111 is formed by heating and stretching the fitting body. Thereafter, after the fitting body is formed as described above, the step of heating and stretching is repeated until a desired number of outer shell portions are obtained. Further, after fitting the n-th outer shell portion 112 which is the outermost shell in the n-th fitting step 104, the desired number of layers is formed on the outer periphery of the core portion by heating and stretching in the n-th heat stretching step 105. The preform 93 provided with the outer shell portion can be obtained. Then, in the heat stretching step 96, the optical member 94 is manufactured by stretching the preform 93 while adjusting the stretching ratio so as to have a desired size. The shape of the cross section of the optical member 94 is substantially similar to the shape of the cross section of the preform 93. Details of manufacturing conditions in the fourth manufacturing process 90 will be described later.

  The outer shell portion of the nth layer provided on the outer periphery of the preform piece 91 may be made of the same material or different materials. That is, when the preform piece 91 includes a core portion and an outer shell portion, and the core portion includes a core portion and a cladding portion, the outer shell portion of the nth layer is formed using the same material as the cladding portion. The outer shell portion of the nth layer may be formed using a material different from that of the cladding portion. For example, in the case of forming a core portion made of a core portion made of PMMA and a clad portion made of PVDF, an outer shell portion of an nth layer made of PVDF can be provided on the outer periphery of the core portion, or this An outer shell portion of an nth layer made of PMMA may be provided on the outer periphery of the core portion.

  An optical member can also be obtained by forming a preform aggregate using a plurality of preforms 93 in the fourth manufacturing step 90 and then heating and stretching the preform aggregate. In this case, the preform aggregate plays a role of the preform.

  Details of the manufacturing conditions in the embodiment according to the present invention will be described below.

  In the present invention, when a preform aggregate is produced using a plurality of preform pieces, the number is not particularly limited, but is preferably 2 or more and 100 or less, more preferably 2 or more and 50 or less, and most preferably 2 or more and 10 or less. Further, the arrangement is not particularly limited, and they may be arranged adjacent to each other or bound together.

  In addition, the preform pieces or intermediate preforms used in forming each preform aggregate are connected by welding or bonding to form a preform aggregate. It is formed. When a plurality of preform pieces are arranged or bundled, an adhesive (for example, urethane compound, epoxy compound, acrylic compound, etc.) may be used at the interface. However, the interfaces and the like may be bonded using a heating and pressing method, an ultrasonic welding method, a vibration welding method, or the like. In addition, welding or adhesion may be performed by heat at the time of heat stretching in addition to performing before heat stretching.

  Further, an outer shell layer may be fitted to the outer periphery of the preform assembly. Thereby, water resistance and toughness can be improved, or variation can be prevented. In addition, when a plurality of preform pieces or intermediate preforms constituting the preform aggregate are bundled, the preform aggregate may be stretched while being aligned without bonding. In this case, the surfaces of the plurality of preform pieces or intermediate preforms adhere to each other at the stage of heat softening in the heating and stretching step performed when forming the optical member, and the cross section of the preform aggregate is substantially the same. An optical member having a similar cross-sectional shape can be obtained. This method is suitable particularly when the number of preform pieces constituting the preform aggregate is small, and has an advantage that the bonding step can be omitted.

  Further, different types of preform pieces may be used, and the optical characteristics of the preform pieces may be different. The outer peripheral shape of the cross section of the preform piece is not limited to a substantially circular shape, and may be any shape that is a combination of a substantially elliptical shape, a polygonal shape, a straight line and a curved line. In addition, as a method of manufacturing preform pieces having different optical characteristics, the constituent materials are changed, the refractive index distribution is changed using a refractive index adjusting agent described later, or additives are selected. However, it is not particularly limited to a method of developing desired optical characteristics.

  A core part is demonstrated among the optical members of this invention. As the polymerizable monomer that is a raw material for the core part, it is preferable to select a raw material that is easily bulk-polymerized. Examples of raw materials that are highly light transmissive and easy to bulk polymerize include the following (meth) acrylic acid esters (fluorine-free (meth) acrylic acid ester (a), fluorine-containing (meth) acrylic acid ester (b) ), Styrenic compounds (c), vinyl esters (d), etc., and the core part is a homopolymer of these, or a copolymer comprising two or more of these monomers, and a homopolymer and / or It can be formed from a mixture of copolymers. Among these, a composition containing (meth) acrylic acid esters as a polymerizable monomer can be preferably used.

Specific examples of the polymerizable monomers listed above include (a) fluorine-free methacrylic acid ester and fluorine-free acrylic acid ester: methyl methacrylate (MMA), ethyl methacrylate, isopropyl methacrylate, methacrylic acid. -tert- butyl, benzyl methacrylate (BzMA), phenyl methacrylate, cyclohexyl methacrylate, diphenylmethyl, tricyclo [5 · 2 · 1 · 0 ^{2, 6]} decanyl methacrylate, adamantyl methacrylate, isobornyl methacrylate, Examples include norbornyl methacrylate, and examples thereof include methyl acrylate, ethyl acrylate, tert-butyl acrylate, and phenyl acrylate. Examples of (b) fluorine-containing acrylic acid ester and fluorine-containing methacrylate ester 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, 2,2, Examples include 3,3,4,4-hexafluorobutyl methacrylate. Furthermore, (c) styrene compounds include styrene, α-methylstyrene, chlorostyrene, bromostyrene, and the like. Examples of (d) vinyl esters include vinyl acetate, vinyl benzoate, vinyl phenyl acetate, and vinyl chloroacetate. Of course, it is not limited to these. The type and composition ratio of the constituent monomers are selected so that the refractive index of the polymer of the core portion made of a monomer alone or a copolymer is equal to or higher than that of the cladding portion. A particularly preferred polymer is polymethyl methacrylate (PMMA), which is a transparent resin.

  Further, when the optical member is used for near-infrared applications, absorption loss due to the C—H bond constituting the polymer of the core portion occurs, so that deuteration as described in Japanese Patent No. 3332922 and the like occurs. Hydrogen atoms (H) of C—H bonds such as polymethyl methacrylate (PMMA-d8), polytrifluoroethyl methacrylate (P3FMA), polyhexafluoroisopropyl 2-fluoroacrylate (HFIP 2-FA), etc. A polymer substituted with a hydrogen atom (D) or fluorine (F) is used. As a result, the wavelength region where transmission loss occurs can be lengthened, and loss of transmission signal light can be reduced. In addition, in order not to impair the transparency after polymerization of the raw material monomer, it is desirable to sufficiently reduce impurities and foreign substances that become scattering sources before polymerization.

  Of the optical member of the present invention, the clad portion will be described. As the material of the clad part, it is preferable to use a material having a lower refractive index than that of the core part and having excellent adhesion to the core part, because light transmitted through the core part is totally reflected at the interface between them. However, if irregularities are likely to occur at the interface between the core part and the clad part due to the selection of the material, or it is not preferable in terms of manufacturing suitability, an additional layer is provided between the core part and the clad part. The consistency may be improved. In this case, for example, when an outer core layer made of a polymer having the same composition as the matrix of the core part is formed on the interface with the core part (that is, the inner wall surface of the hollow tube), the interface state between the core part and the cladding part is changed. It can be corrected. Details of the outer core layer will be described later. Of course, the clad part itself may be formed from a polymer having the same composition as the matrix of the core part without forming the outer core layer.

  As the material for the clad part, a material excellent in toughness and heat-and-moisture resistance is preferably used. For example, suitable materials include homopolymers or copolymers of fluorine-containing monomers. As the fluorine-containing monomer, vinylidene fluoride (PVDF) is preferable, and a fluorine resin obtained by polymerizing one or more polymerizable monomers containing 10% by mass or more of vinylidene fluoride is preferably used.

  In addition, when a polymer is formed by melt extrusion to produce a clad part, it is necessary that the polymer has an appropriate melt viscosity. As for the melt viscosity, the molecular weight is used as a correlated physical property, and particularly has a correlation with the weight average molecular weight. In the present invention, the weight average molecular weight is suitably in the range of 1 to 1,000,000, more preferably in the range of 5 to 500,000.

  Furthermore, it is preferable to prevent moisture from entering the core portion. For this purpose, a polymer having a low water absorption rate is used as a material (material) for the cladding portion. That is, it is preferable to produce a clad part using a polymer having a saturated water absorption rate (hereinafter referred to as a water absorption rate) of less than 1.8%. More preferably, the clad portion is formed using less than 1.5% polymer, and more preferably less than 1.0% polymer. Further, it is preferable to use a polymer having the same water absorption rate when the outer core layer is produced. The water absorption rate (%) can be calculated by immersing the test piece in water at 23 ° C. for 1 week according to the ASTM D 570 test method and measuring the water absorption rate at that time.

  When the core part and / or the clad part are made from a polymer polymerized from a polymerizable monomer, a polymerization initiator is used in the polymerization. As a polymerization initiator, it can select suitably according to the monomer and polymerization method to be used, for example, benzoyl peroxide (BPO), tert- butyl peroxy-2-ethyl hexanate (PBO), di-tert-butyl. Examples thereof include peroxide compounds such as peroxide (PBD), tert-butyl peroxyisopropyl carbonate (PBI), and n-butyl-4,4-bis (tert-butylperoxy) valerate (PHV). 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-methylhexane), 3,3′-azobis (3,4-dimethylpentane), 3,3'-azobis 3-ethylpentane), dimethyl-2,2′-azobis (2-methylpropionate), diethyl-2,2′-azobis (2-methylpropionate), di-tert-butyl-2,2 ′ -Azo compounds such as azobis (2-methylpropionate). Of course, the polymerization initiator is not limited to these, and two or more kinds may be used in combination.

  The polymerizable composition for forming a core part and the polymerizable composition for forming a clad part preferably contain a chain transfer agent. Chain transfer agents are mainly used to adjust the molecular weight of the polymer. When the polymerizable composition for forming the cladding part and the core part each contains a chain transfer agent, the polymerization rate and the degree of polymerization can be more controlled by the chain transfer agent when forming the polymer from the polymerizable monomer. The molecular weight of the polymer can be adjusted to a desired molecular weight. For example, when forming the optical member by drawing the obtained preform by stretching, the mechanical properties at the time of stretching can be adjusted to a desired range by adjusting the molecular weight, which also improves productivity. Contribute.

  About a chain transfer agent, according to the kind of polymerizable monomer used together, a kind and addition amount can be selected suitably. The chain transfer constant of the chain transfer agent for each monomer can be referred to, for example, Polymer Handbook 3rd Edition (J. BRANDRUP and EH IMMERGUT edition, published by JOHN WILEY & SON). The chain transfer constant can also be obtained by experiment with reference to Takayuki Otsu and Masato Kinoshita, “Experimental Methods for Polymer Synthesis”, Kagaku Dojin, published in 1972.

  Examples of chain transfer agents include alkyl mercaptans (for example, n-butyl mercaptan, n-pentyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, tert-dodecyl mercaptan), thiophenols (for example, thiophenol, m- Bromothiophenol, p-bromothiophenol, m-toluenethiol, p-toluenethiol, etc.) are preferably used. In particular, it is preferable to use an alkyl mercaptan such as n-octyl mercaptan, n-lauryl mercaptan, and tert-dodecyl mercaptan. A chain transfer agent in which a hydrogen atom of a C—H bond is substituted with a deuterium atom (D) or a fluorine atom (F) can also be used. Of course, the chain transfer agent is not limited to these, and two or more of these chain transfer agents may be used in combination.

  The core part polymerizable composition preferably contains a refractive index adjusting agent. The refractive index adjusting agent is also called a dopant, and is a compound different from the refractive index of the polymerizable monomer used together. In addition, you may make a clad part polymeric composition contain a refractive index adjusting agent as needed. By providing a distribution in the concentration of the refractive index adjusting agent, a refractive index distribution type core can be easily produced based on the concentration distribution. At this time, the difference in refractive index is preferably 0.005 or more. However, it is possible to introduce a refractive index distribution structure by using two or more kinds of polymerizable monomers for forming the core portion and providing a distribution of the copolymerization ratio in the core portion without using a refractive index adjusting agent. it can.

The dopant has the property that the polymer containing it has a higher refractive index than the additive-free polymer. These have a difference in solubility parameter of 7 (cal / cm ^{3) in} comparison with a polymer produced by monomer synthesis as described in Japanese Patent No. 3333292 and Japanese Patent Laid-Open No. 5-173026. ) Within ^1/2 , and the difference in refractive index is 0.001 or more, and the polymer containing this has the property of changing the refractive index as compared to the additive-free polymer. Any of those that can stably coexist and are stable under the polymerization conditions (polymerization conditions such as heating and pressurization) of the above-described polymerizable monomer can be used.

  Using the above-mentioned properties as a dopant that can stably coexist with a polymer and is stable under the polymerization conditions (polymerization conditions such as heating and pressurization) of the above-described raw material polymerizable monomer. Can do. For example, the core portion-forming polymerizable composition contains a dopant, and in the step of forming the core portion, the polymerization progress direction is controlled by radical polymerization, the dopant concentration is inclined, and the dopant concentration distribution in the core portion. And a method of forming a refractive index distribution structure based on the above. In this refractive index distribution structure, the refractive index changes from the center to the outer periphery in the cross section, the GI type in which the refractive index gradually decreases from the center to the outer periphery, and the refractive index from the center to the outer periphery. There is a multi-step index (MI) type that gradually becomes lower as it goes. These GI type or MI type optical members have a wide transmission band.

  The dopant may be a polymerizable compound. When a dopant of the polymerizable compound is used, a copolymer containing this as a copolymerization component has a higher refractive index than a polymer not containing this. Use those with properties. Examples of such a copolymer include MMA-BzMA copolymer.

  Examples of the dopant include, for example, benzyl benzoate (BEN), diphenyl sulfide (DPS), triphenyl phosphate (TPP), and benzyl phthalate, as described in Japanese Patent No. 3332922 and JP-A-11-142657. -N-butyl (BBP), diphenyl phthalate (DPP), diphenyl (DP), diphenylmethane (DPM), tricresyl phosphate (TCP), diphenyl sulfoxide (DPSO), sulfurized diphenyl derivatives, dithian derivatives and the like. Among them, BEN, DPS, TPP, DPSO, sulfurized diphenyl derivatives, and dithian derivatives are preferable. In addition, compounds obtained by substituting hydrogen atoms present in these compounds with deuterium atoms can also be used for the purpose of improving transparency in a wide wavelength region. Examples of the polymerizable compound include tribromophenyl methacrylate. When a polymerizable compound is used as the refractive index adjusting component, it is difficult to control various characteristics (particularly optical characteristics) because the polymerizable monomer and the polymerizable refractive index component are copolymerized when forming the matrix. However, it may be advantageous in terms of heat resistance.

  By adjusting the concentration and distribution of the dopant, the refractive index of the optical member can be changed to a desired value. The amount added is appropriately selected according to the use and the member to be combined. A plurality of dopants may be added.

  In addition to the dopant and the like, the core part, the clad part, or a part thereof may contain an additive in the polymerizable composition constituting the core as long as the optical transmission performance is not deteriorated. For example, a stabilizer can be added to the core portion or a part thereof for the purpose of improving weather resistance, durability, and the like. In addition, for the purpose of improving optical transmission performance, a stimulated emission functional compound for optical signal amplification can also be added. By adding the stimulated emission functional compound, the attenuated signal light can be amplified by the excitation light, and the transmission distance is improved. For example, it can be used as an optical fiber amplifier in a part of the optical transmission link. . These additives can also be contained in the core part, the clad part or a part of them by adding to the raw material monomer and then polymerizing.

  It is preferable to provide a coating layer on the outer periphery of the clad portion after heat-stretching by extrusion molding of a molten resin or the like for the purpose of improving waterproofness and durability. The material of the coating layer is not particularly limited, and for example, a thermoplastic resin is used. Particularly, a polyolefin-based resin is preferably used because it has good chemical resistance and flexibility. Examples of the polyolefin-based resin include polymers such as ethylene, propylene, and α-olefin. Examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-peptene, and 1-octene. Examples of these polymers include polyethylene. And copolymers of ethylene and propylene, copolymers of ethylene and α-olefin, polypropylene, copolymers of propylene and α-olefin, polybutene, polyisoprene and the like. In addition, the polyolefin resin may be blended in an appropriate combination in consideration of the physical properties to be obtained. In addition, although the molecular weight and molecular weight distribution of polyolefin resin are not specifically limited, The weight average molecular weight is 5000-5 million normally, Preferably it is 20000-300000. And the molecular weight distribution shown by weight average molecular weight Mw / number average molecular weight Mn is 1-80, Preferably it is set to 1-40.

  Moreover, after apply | coating a radiation curable resin or a thermosetting resin, it is good also as making it harden | cure by irradiating a radiation or applying heat, and it is good also as a coating material. Examples of the radiation curable resin include acrylic-modified unsaturated polyester, epoxy resin, and polyurethane, and examples of the thermosetting resin include phenol resin, melamine resin, and diacryl phthalate resin. In addition, the coating layer may be not only a single layer but also a multilayer. In the case of multiple layers, tensile strength fibers or the like may be disposed between them.

  In each of the embodiments described above, the core may contain light scattering particles in advance. The size of the light scattering particles is not particularly limited, but those having an average particle diameter of 1 μm or more and 2 μm or less are preferably used. The material is not particularly limited, but silicon particles, silica particles, polystyrene particles, zirconia beads, melamine particles, and the like are preferably used, and silicon particles are particularly preferably used. By containing light scattering particles in the core 42, the optical interconnection technology application such as the optical bus (sheet bus) disclosed in JP-A-10-186184, and different light scattering particle concentration units are patterned. The optical member of the present invention can be used for light guide member applications such as a light guide plate, a diffusion sheet, and a reflector plate that are arranged in a shape and locally change the light scattering ability.

  The optical transmission material of the present invention is used in an optical signal processing apparatus including optical components such as various light emitting elements, light receiving elements, optical switches, optical isolators, optical integrated circuits, and optical transmission / reception modules. Alternatively, it may be combined with an optical fiber or an optical waveguide made of plastic. Any known technique can be applied as a technique related to them. For example, the basic and actual of plastic optical fiber (published by NTS Corporation), Nikkei Electronics 2001.1.2.3, pp. 110-127 “Printed Wiring You can refer to "This time, optical components are mounted on the board." By combining with various techniques described in the above-mentioned documents, the optical member of the present invention is used for internal wiring in computers and various digital devices, internal wiring for vehicles and ships, optical transmission systems, and the like. The optical transmission system is used for high-speed and large-capacity data communication and control applications that are not affected by electromagnetic waves, and particularly preferably for short-distance applications. Specific examples of this optical transmission system include data communication optical terminals and digital devices, optical links between digital devices, and indoor or regional optical LANs in ordinary homes, apartment houses, factories, offices, hospitals, schools, etc. .

  Further, IEICE TRANS. ELECTRON. , VOL. E84-C, no. 3, MARCH 2001, p. 339-344 “High Uniformity Star Coupler Using Diffused Light Transmission”, Journal of Japan Institute of Electronics Packaging, Vol. 3, no. 6, 2000, pages 476 to 480, as described in "Interconnection with Optical Sheet Bus Technology", and Japanese Patent Laid-Open Nos. 10-123350, 2002-90571, 2001-290055, and the like. Optical buses described: Japanese Patent Laid-Open Nos. 2001-74971, 2000-329962, 2001-74966, 2001-74968, 2001-318263, 2001-31840, etc. Optical star couplers described in JP 2000-241655 A, etc .; JP 2002-624457, JP 2002-101044, JP 2001-305395 A, etc. Optical signal transmission apparatus and optical bus system; optical signal processing described in JP-A-2002-23011, etc. Optical device: optical signal cross-connect system described in Japanese Patent Application Laid-Open No. 2001-86537, etc .; optical transmission system described in Japanese Patent Application Laid-Open No. 2002-26815; Multi-function system as described in the above; and various optical waveguides, optical splitters, optical couplers, optical multiplexers, optical demultiplexers, etc., combined with transmission / reception, etc., for more advanced optical transmission A system can be constructed. In addition to the above optical transmission applications, the plastic optical member of the present invention can be used in the fields of illumination, energy transmission, illumination, and sensors.

  Hereinafter, the manufacturing method of the optical member according to the present invention will be described more specifically with reference to Examples 1 to 5. It should be noted that the types of materials, ratios thereof, prescriptions, and the like shown in the following examples may be appropriately changed without departing from the spirit of the present invention. Accordingly, the scope of the present invention is not limited to the following examples.

  In the first embodiment, the first manufacturing step 11 shown in FIG. 1, the core portion 15 including the core portion 25 a and the clad portion 26 a as shown in FIG. 3A, and the outer shell portion 16 having the fitting hole 27. Are formed into a preform 12 as shown in FIG. 3 (B), and the preform 12 is heated and stretched to obtain an optical member 10 as shown in FIG. 3 (C). Manufactured.

  First, using PMMA, a PMMA rod having a diameter of 20 mm and a length of 400 mm was produced as a core portion 25a by melt extrusion molding. Next, the PMMA rod is inserted and fitted into a clad pipe made of PVDF having an inner diameter of 20.3 mm, an outer diameter of 21.3 mm, and a length of 400 mm prepared in advance by the same melt extrusion molding as described above. A core portion 15 was formed. Then, a PMMA rod having a fitting hole 27 with a diameter of 21.6 mm, which is formed in advance by melt extrusion molding, has a square cross section, a side of 34 × 34 mm, and a length of 400 mm is used as the outer shell portion 16. Then, the core portion 15 and the outer shell portion 16 were fitted to form a preform 12. Finally, the optical member 10 was manufactured by heating and stretching the void 28 while reducing the pressure. Prior to heating and stretching, the preform 12 was vacuum-treated while being heated to 90 ° C., and the fixed end portion was fixed by heat fusion with a heater.

  The optical member 10 obtained as described above was composed of a core member 15a including a core 25b of φ205 μm and an outer shell member 16a, and the cross-sectional shape was 350 × 350 μm. Further, when the transmission loss of the optical member 10 was measured, it was 0.04 dB / cm at a wavelength of 850 nm, indicating a very low transmission loss.

  In Example 2, the first manufacturing process 11 shown in FIG. 1 is applied, and the outer shell portion 30 as shown in FIG. 5A, the core portion A33 and the core portion B34 as shown in FIG. 5B. And a preform 35 as shown in FIG. 5C was formed, and this was heated and stretched to produce an optical member 38 as shown in FIG. 5D.

  First, the core part A33 and the core part B34 of different sizes were produced. As the core part A33, a PVDF pipe having an inner diameter of 9 mm and an outer diameter of 10 mm to be the clad part A33b is prepared. In this, a deuterated MMA in which DPS, a polymerization initiator, and a chain transfer agent are added as a refractive index adjusting agent. Then, the core part A33a was formed by radical polymerization of the core part A33a. Also, as the core part B34, a PVDF pipe having an inner diameter of 14 mm and an outer diameter of 15 mm to be the cladding part B34b is prepared, and after deuterated MMA added with DPS as a refractive index adjusting agent is injected into this, Was subjected to radical polymerization to form the core part B34a. As described above, two core parts A33 and two core parts B34 were formed, and then the preform 35 was manufactured by fitting them with the outer shell part 30. The outer shell 30 was provided with two fitting holes 31 of φ10.3 mm and two fitting holes 32 of φ15.3 mm, and the cross-sectional shape was a rectangle of 20 × 80 mm. And the optical member 38 was manufactured by heat-extending the space | gap A36 and space | gap B37 of this preform 35, reducing pressure, respectively. However, before the heat stretching, the preform 35 was heat-depressurized within a predetermined range, and the fixed end was fixed with a heat-resistant tape.

  The optical member 38 obtained as described above had an outer shape of a cross section of 200 × 800 μm, and had a core member A39 having a diameter of 90 μm and a core member B40 having a diameter of 140 mm, each having two cores. The cross-sectional shape of the preform 35 is substantially similar to the cross-sectional shape of the preform 35. When the transmission loss of the optical member 38 was measured, all of them were 0.03 dB / cm at a wavelength of 850 nm, indicating a very low transmission loss.

  In Example 3, after applying the second manufacturing process 50 shown in FIG. 6 to form a preform piece 51 as shown in FIG. 9A, four preforms as shown in FIG. 9B are formed. An optical member 53 as shown in FIG. 9C was manufactured by arranging the reforming pieces 51 to form a preform assembly 52 and then heating and stretching it.

  First, the core part 60 and the outer shell part 61 were produced, respectively. The core part 60 is made of PMMA using a PMMA rod having a diameter of 20 mm and a length of 400 mm as a core part by melt extrusion molding. Then, the core part 60 is produced by melt extrusion molding and has an inner diameter of 20.3 mm and an outer diameter of 21.3 mm. The clad part was formed on the outer periphery of the core part by inserting it into a clad pipe made of PVDF having a length of 400 mm and fitting it. Also, as the outer shell 61, a PMMA rod having a fitting hole with a diameter of 21.6 mm, a square cross section, 34 × 34 mm and a length of 400 mm is formed by melt extrusion. did. Next, the preform piece 51 having the gap 120 was formed by fitting the core portion 60 and the outer shell portion 61 together. At this time, the end portion of the preform piece 51 located on the extending direction side was fixed with a heat-resistant tape. By preparing four preform pieces 51 by the above method and arranging them closely, a preform aggregate 52 having a rectangular cross section and an outer shape of 34 × 136 mm was formed. . Subsequently, the preform assembly 52 was subjected to heat and pressure reduction treatment within a desired range, and then the optical members 53 were manufactured by heating and stretching each gap 120 while reducing the pressure. In addition, since the interface of each preform piece 51 constituting the preform aggregate 52 was fused by heat at the time of heating and stretching, it was not necessary to use an adhesive.

  The optical member 53 obtained as described above is composed of the core member 121 and the outer shell member 122. The cross-sectional shape is 350 × 1400 μm, and the cross-sectional shape is substantially similar to the preform assembly 52. . When the transmission loss of this optical member 53 was measured, it was 0.04 dB / cm at a wavelength of 850 nm, indicating a very low transmission loss.

  In Example 4, after applying the 3rd manufacturing process 70 shown in FIG. 7 and forming the preform piece 71 as shown to FIG. 10 (A), this is once heat-expanded, and FIG. An intermediate preform 72 as shown in FIG. After preparing five intermediate preforms 72 by the above method and arranging them, a preform aggregate 73 as shown in FIG. 10C is formed, and then this preform aggregate 73 is formed. Was stretched by heating to produce an optical member 74 shown in FIG.

  In Example 4, the preform 12 formed in Example 1 was used as the preform piece 71, and this preform piece 71 was heated and stretched to obtain an intermediate preform 72. The intermediate preform 72 includes a first core member 131 and a first outer shell member 132 formed by heating and stretching the core portion 15 and the outer shell portion 16, respectively. A square with a side of 8 × 8 mm. Then, after preparing five intermediate preforms 72, the preforms 73 having an outer shape of 8 × 40 mm were formed by arranging them so that the cross-sectional shape was rectangular. Subsequently, the preform assembly 52 is subjected to heat and pressure reduction treatment within a desired range, and then the preform assembly 73 is heated and stretched so that the cross-sectional shape of the optical member 74 is substantially similar. Thus, an optical member 74 was manufactured. In Example 4, since the interface of each intermediate preform 72 was fused by heating when the preform aggregate 73 was heated and stretched, it was not necessary to use an adhesive.

  The optical member 74 obtained as described above includes a second core member 133 in which the first core member 131 is heated and stretched, and a second outer shell member 134 in which the first outer shell member 132 is heated and stretched. The second core member 133 was a five-core optical waveguide having five cores (not shown) having a φ147 μm core. Moreover, the shape of the cross section was substantially similar to the shape of the cross section of the preform aggregate 73, and the outer shape was a rectangle of 250 × 1250 μm. As in Example 1, the transmission loss of the optical member 74 was 0.04 dB / cm at a wavelength of 850 nm for all the single cores, indicating a very low transmission loss.

  In Example 5, the fourth manufacturing process 90 shown in FIG. 8 is applied to produce a preform piece 91 as shown in FIG. 11A, which is then heated and stretched once, and FIG. A first intermediate preform 92 as shown in FIG. Subsequently, after the second outer shell portion 110 is fitted to the first intermediate preform 92, this is heated and stretched to form the second intermediate preform 111. Subsequently, the fitting and heating and stretching steps are performed. By repeating the process five times, a preform 93 as shown in FIG. The preform 93 was heated and stretched to produce an optical member 94. As the preform piece 91, the preform 12 formed in Example 1 was used. However, in Example 5, in order to produce an intermediate preform by heating and stretching the preform piece 91, for the sake of convenience of explanation, such as distinguishing from members constituting the first intermediate preform 92, etc. Of the preform 12 (FIG. 3B), the names are changed with the core 15 as the core precursor 140 and the outer shell 16 as the first outer shell precursor 141.

  First, the prepared preform piece 91 was heated and stretched to obtain a first intermediate preform 92. The first intermediate preform 92 was formed of a core part 145 obtained by heating and stretching the core part precursor 140 and a first outer shell part 146 obtained by heating and stretching the first outer shell part precursor 141. Next, the first intermediate preform 92 and a second outer shell portion 110 formed in advance by commercially available melt extrusion molding using PMMA were fitted to form a second intermediate preform 111. The preform 93 having a multi-layered outer shell portion 150 in which the first outer shell portion 146 to the sixth outer shell portion 112 are sequentially formed by repeating this fitting and heating and stretching step four times continuously. Formed. This preform 93 had a cross-sectional shape of a square having a side of 15 × 15 mm. Finally, the preform 93 was heated and stretched to produce an optical member 94. The preform 93 before being heated and stretched was subjected to a heat and pressure reduction treatment within a predetermined range.

  The optical member 94 obtained as described above is composed of a core member 151 and an outer shell member 152, and the outer shape thereof is a square having a side of 150 × 150 μm. The shape of the cross section was substantially similar to the shape of the cross section of the preform 93. The transmission loss of the optical member 94 was 0.04 dB / cm at the wavelength of 850 nm in the same manner as in Example 1, indicating a very low transmission loss.

It is a 1st manufacturing-process figure which shows the manufacturing method of the optical member which concerns on this invention. It is explanatory drawing of the heating extending process in the manufacturing method of the optical member which concerns on this invention. It is the schematic of an example explaining the 1st manufacturing process of the optical member concerning this invention. It is the schematic of an example explaining fixation of the edge part of the optical member which concerns on this invention. It is the schematic of an example explaining the 1st manufacturing process of the optical member which concerns on this invention. It is a 2nd manufacturing process figure which shows the manufacturing method of the optical member which concerns on this invention. It is a 3rd manufacturing process figure which shows the manufacturing method of the optical member which concerns on this invention. It is a 4th manufacturing-process figure which shows the manufacturing method of the optical member which concerns on this invention. It is the schematic of an example explaining the 2nd manufacturing process of the optical member which concerns on this invention. It is the schematic of an example explaining the 3rd manufacturing process of the optical member which concerns on this invention. It is the schematic of an example explaining the 4th manufacturing process of the optical member which concerns on this invention.

Explanation of symbols

10, 38, 53, 74, 94 Optical members 12, 35, 93 Preforms 15, 60, 87, core parts 16, 30, 61, 88, outer shell part 25a core part 26a clad part 27 fitting holes 28, 120 , Voids 51, 71, 91 preform pieces 52, 73, preform aggregate 72 intermediate preform 92 first intermediate preform 111 second intermediate preform

Claims (19)

In a method for producing a plastic optical member by stretching an optical member preform,
An optical member preform forming step for forming the optical member preform by fitting a plurality of optical member preform pieces formed from a polymer;
A method for producing a plastic optical member, comprising: a heat stretching step in which a shape of a cross section of the plastic optical member is stretched so as to be substantially similar to a cross sectional shape of the optical member preform. The optical member preform piece is composed of a core portion serving as an optical transmission path and an outer shell portion provided with a hollow fitting hole,
2. The method of manufacturing a plastic optical member according to claim 1, wherein, in the optical member preform forming step, the core portion is inserted into a fitting hole provided in the outer shell portion.   3. The method of manufacturing a plastic optical member according to claim 1, wherein the plastic optical member has a cross-sectional shape that is a figure combining polygons, closed curves, straight lines, and curves.   The method of manufacturing a plastic optical member according to claim 2, wherein the core includes a core serving as an optical transmission path.   5. The method of manufacturing a plastic optical member according to claim 2, wherein the core portion includes the core portion and a clad portion having a lower refractive index than the core portion around the core portion.   6. The method of manufacturing a plastic optical member according to claim 2, wherein the outer shell part includes at least one of protective layers for protecting the clad part and the core part. The shape of the cross section of the core portion and the shape of the cross section of the fitting hole are substantially similar,
The plastic optical member according to claim 2, wherein a clearance X (mm) of a gap formed when the core portion is fitted in the fitting hole satisfies a condition of 0 <X ≦ 8. Production method.   The method for producing a plastic optical member according to claim 7, wherein the optical member preform is heated and stretched while the gap is reduced.   The method for manufacturing a plastic optical member according to claim 2, wherein the outer shell portion includes a plurality of the fitting holes.   4. The plastic optical member according to claim 1, wherein the optical member preform is an optical member preform assembly formed by arranging single-core optical member preforms having a single-core structure. Manufacturing method.   11. The method for producing a plastic optical member according to claim 10, wherein the optical member preform aggregate is constituted by an intermediate optical member preform formed by heating and stretching the single-core optical member preform.   The method for producing a plastic optical member according to claim 10 or 11, wherein the optical member preform aggregate is formed by adhering adjacent single-core optical member preforms.   The method for producing a plastic optical member according to any one of claims 10 to 12, wherein the optical member preform aggregate is formed by fusing adjacent single-core optical member preforms.   The method for producing a plastic optical member according to claim 13, wherein the single-core optical member preform is fused before heating and stretching.   The method for producing a plastic optical member according to claim 13, wherein the single-core optical member preform is fused by heating at the time of heating and stretching.   The method for producing a plastic optical member according to any one of claims 10 to 13, wherein the optical member preform aggregate includes the single-core optical member preforms having different shapes.   The method for producing a plastic optical member according to any one of claims 10 to 13, wherein the optical member preform aggregate includes the single-core optical member preform exhibiting different optical characteristics. The core part includes an acrylic polymer,
3. The method for producing a plastic optical member according to claim 1, wherein at least one of the core portion and the outer shell portion is a polymer containing a fluorine atom. 19. The method of manufacturing a plastic optical member according to claim 18, wherein the refractive index of the core portion gradually changes from the center toward the outside in the cross section thereof.

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