Plastic optical fiber manufacturing device and manufacturing method

Abstract

The present invention provides a plastic optical fiber manufacturing device suitable for suppressing the incorporation of metal, which causes increased transmission loss in plastic optical fibers, and uniformly adjusting the thickness of the plastic optical fibers. The plastic optical fiber manufacturing device of the present invention comprises an extruder and a gear pump. The extruder has a container for accommodating a resin composition, into which gas is introduced and extruded from the container using the gas. The gear pump adjusts the flow rate of the resin composition extruded from the extruder.

Description

Technical Field

[0001] The present invention relates to a manufacturing device and a manufacturing method of plastic optical fiber. Background Art

[0002] Compared to quartz glass optical fibers, plastic optical fibers have lower production costs, better flexibility, and superior processability. They are primarily used as a transmission medium for short distances (e.g., less than 100 m).

[0003] Plastic optical fibers, like glass optical fibers, typically have a core at the center that transmits light and a cladding covering the core. The core of a plastic optical fiber is made of a resin with a high refractive index, while the cladding is made of a resin with a lower refractive index than the core.

[0004] Plastic optical fiber can be manufactured by, for example, melt spinning. In the melt spinning method, the resin composition is extruded from an extruder, thereby forming the resin composition into a fiber. For example, Patent Document 1 discloses using an extruder equipped with a screw to extrude the resin composition from the extruder. Patent Document 2 discloses introducing a gas into the extruder, utilizing the gas to press the resin composition and extrude the resin composition from the extruder.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-356716

[0008] Patent Document 2: U.S. Patent No. 6,527,986 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] In an extruder equipped with a screw, when extruding a resin composition, the screw rubs against the wall of the housing that is provided with the resin composition. Thus, the screw or the housing are slightly ground, and their materials, such as metals, are mixed into the resin composition. When metals are mixed into the resin composition, even if the amount of metals mixed into the resin composition is minute, there is a trend that transmission loss significantly increases in the plastic optical fiber having the core formed by the resin composition.

[0011] An extruder using gas can suppress the incorporation of metal into a resin composition. However, when the resin composition is formed into a fiber using such an extruder, the thickness (diameter) of the resulting molded article tends to be non-uniform.

[0012] Therefore, an object of the present invention is to provide a plastic optical fiber manufacturing apparatus suitable for suppressing the incorporation of metal that causes an increase in transmission loss of the plastic optical fiber and adjusting the thickness of the plastic optical fiber to be uniform.

[0013] Means for solving problems

[0014] According to the research of the present inventors, it is known that in the extrusion device using gas, even if the pressure of the gas imported is maintained to be constant, if the viscosity and temperature of resin combination are uneven, the flow of the resin combination extruded also can change.In addition, it is known that if there is hold-up in stream, the pressure loss changes, so flow changes in the same way.The present inventors have found that the variation of this flow becomes the main cause making the thickness inhomogeneous of fibrous formed body, thereby completed the present invention.

[0015] The present invention provides a device for manufacturing a plastic optical fiber, comprising:

[0016] an extrusion device having a housing for housing a resin composition, wherein a gas is introduced into the housing to extrude the resin composition from the housing using the gas; and

[0017] A gear pump adjusts the flow rate of the resin composition extruded from the extrusion device.

[0018] Effects of the Invention

[0019] According to the present invention, it is possible to provide a plastic optical fiber manufacturing apparatus suitable for suppressing the incorporation of metal that causes an increase in transmission loss of the plastic optical fiber and adjusting the thickness of the plastic optical fiber to be uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing an example of a manufacturing apparatus for a plastic optical fiber.

[0021] Figure 2 This is a diagram for explaining a pair of gears included in a gear pump.

[0022] Figure 3 yes Figure 2 An enlarged view of region III is shown.

[0023] Figure 4 This is a cross-sectional view of the gear pump showing the outer peripheral surfaces of a pair of gears included in the gear pump.

[0024] Figure 5 This is a diagram showing another example of a plastic optical fiber manufacturing apparatus.

[0025] Figure 6 is the maximum value τ of the shear stress in Measurement Examples 1 to 18 TC and τSC diagram of the relationship between . DETAILED DESCRIPTION

[0026] The present invention provides a method for manufacturing a plastic optical fiber from another aspect.

[0027] The present invention relates to a method for manufacturing plastic optical fiber using the above-mentioned manufacturing device.

[0028] The manufacturing method includes the steps of passing the resin composition extruded from the extrusion device through a gear pump,

[0029] The gear pump comprises a housing through which a resin composition passes and a pair or more of gears housed in the housing and meshing with each other.

[0030] The maximum value of the shear stress generated in the resin composition between the tooth portion of one of a pair of or more gears and the housing is represented by τ. TC (kPa), the maximum value of the shear stress generated in the resin composition between the side of the gear and the housing is expressed as τ SC (kPa), the following relational formula (I) is satisfied.

[0031] τ SC ≤-τ TC +1200 (I)

[0032] In one aspect of the present invention, in the above-mentioned manufacturing method, at least one selected from the distance between the teeth of the gear and the housing and the distance between the side surface of the gear and the housing is 5 μm or greater.

[0033] In one aspect of the present invention, in the above-mentioned manufacturing method, the diameter of the side surface of the gear is 80 mm or less.

[0034] In one embodiment of the present invention, in the above-mentioned manufacturing method, the rotation speed of the gear is 100 rpm or less.

[0035] In one embodiment of the present invention, in the above-mentioned manufacturing method, the inner side surface of the housing is made of a material having corrosion resistance to the resin composition.

[0036] In one embodiment of the present invention, in the above-mentioned manufacturing method, surfaces of the one or more gears are made of a material having corrosion resistance to the resin composition.

[0037] In one embodiment of the present invention, in the above-mentioned production method, the material having corrosion resistance to the resin composition includes at least one selected from Hastelloy and Stellite.

[0038] The present invention provides a method for manufacturing a plastic optical fiber from another aspect.

[0039] The present invention relates to a method for manufacturing plastic optical fiber using the above-mentioned manufacturing device.

[0040] The manufacturing method comprises the steps of extruding the resin composition from an extrusion device,

[0041] The viscosity of the resin composition extruded from the extruder is 1 to 7000 Pa·s.

[0042] The present invention provides a method for manufacturing a plastic optical fiber from another aspect.

[0043] The present invention relates to a method for manufacturing plastic optical fiber using the above-mentioned manufacturing device.

[0044] The manufacturing method includes the steps of delivering the resin composition from a gear pump,

[0045] The flow rate of the resin composition delivered from the gear pump was 20 L / min or less.

[0046] The present invention provides a method for manufacturing a plastic optical fiber from another aspect.

[0047] The present invention relates to a method for manufacturing plastic optical fiber using the above-mentioned manufacturing device.

[0048] The manufacturing method includes the steps of passing the resin composition extruded from the extrusion device through a gear pump,

[0049] The increase in the metal concentration in the resin composition before and after passing through the gear pump was 100 ppm by mass or less.

[0050] The present invention provides a method for manufacturing a plastic optical fiber from another aspect.

[0051] The present invention relates to a method for manufacturing plastic optical fiber using the above-mentioned manufacturing device.

[0052] A plastic optical fiber is produced using a resin composition containing a polymer having a structural unit represented by the following formula (1).

[0053]

Chemical Formula 1

[0054]

[0055] In formula (1), R ff 1 ~R ff 4 Each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms, or a perfluoroalkyl ether group having 1 to 7 carbon atoms. ff 1 With R ff 2 Can be linked to form a ring.

[0056] The present invention provides a method for manufacturing a plastic optical fiber from another aspect.

[0057] The present invention relates to a method for manufacturing plastic optical fiber using the above-mentioned manufacturing device.

[0058] This production method includes the step of shaping the resin composition delivered from a gear pump into a fiber shape.

[0059] From another aspect, the present invention provides a device for manufacturing a plastic optical fiber, comprising:

[0060] an extrusion device having a housing for housing a resin composition, wherein a gas is introduced into the housing to extrude the resin composition from the housing; and

[0061] The gear pump adjusts the flow rate of the resin composition extruded from the extruder.

[0062] In one embodiment of the present invention, in the above-mentioned manufacturing apparatus,

[0063] The gear pump comprises a housing through which a resin composition passes and a pair or more of gears housed in the housing and meshing with each other.

[0064] The maximum value of the shear stress generated in the resin composition between the tooth portion of one of the pair of gears and the housing is represented by τ TC (kPa), the maximum value of the shear stress generated in the resin composition between the side of the gear and the housing is expressed as τ SC (kPa), the following relational formula (I) is satisfied.

[0065] τ SC ≤-τ TC +1200 (I)

[0066] In one aspect of the present invention, in the manufacturing apparatus described above, at least one selected from the group consisting of a distance between a tooth portion of the gear and the housing and a distance between a side surface of the gear and the housing is 5 μm or greater.

[0067] In one aspect of the present invention, in the above-mentioned manufacturing apparatus, the diameter of the side surface of the gear is 80 mm or less.

[0068] In one aspect of the present invention, in the above-mentioned manufacturing apparatus, the rotation speed of the gear is 100 rpm or less.

[0069] In one aspect of the present invention, in the above-mentioned manufacturing apparatus, the inner side surface of the housing is made of a material having corrosion resistance to the resin composition.

[0070] In one embodiment of the present invention, in the above-mentioned manufacturing apparatus, surfaces of the one or more gears are made of a material having corrosion resistance to the resin composition.

[0071] In one embodiment of the present invention, in the above-mentioned production apparatus, the material having corrosion resistance to the resin composition includes at least one selected from the group consisting of Hastelloy and Stellite.

[0072] In one embodiment of the present invention, in the above-mentioned production apparatus, the viscosity of the resin composition extruded from the extruder is 1 to 7000 Pa·s.

[0073] In one embodiment of the present invention, in the above-mentioned production apparatus, the flow rate of the resin composition delivered from the gear pump is 20 L / min or less.

[0074] In one embodiment of the present invention, in the above-mentioned production apparatus, an increase in the metal concentration in the resin composition before and after passing through the gear pump is 100 ppm by mass or less.

[0075] In one embodiment of the present invention, in the above-mentioned production apparatus, the resin composition contains a polymer having a structural unit represented by the following formula (1).

[0076]

Chemical Formula 2

[0077]

[0078] In formula (1), R ff 1 ~R ff 4 Each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms, or a perfluoroalkyl ether group having 1 to 7 carbon atoms. ff 1 With R ff 2 Can be linked to form a ring.

[0079] In one embodiment of the present invention, the production apparatus forms the resin composition delivered from the gear pump into a fiber shape.

[0080] Hereinafter, embodiments of the present invention will be described. However, the following description is not intended to limit the present invention to the specific embodiments.

[0081] (Implementation Method 1)

[0082] like Figure 1As shown, a plastic optical fiber (POF) manufacturing apparatus 100 according to the first embodiment includes an extruder 1 and a gear pump 2. The extruder 1 includes a container 10 for containing a resin composition 5. By introducing a gas into the container 10, the resin composition 5 can be extruded from the container 10. The gear pump 2 adjusts the flow rate of the resin composition 5 extruded from the extruder 1.

[0083] The housing 10 of the extrusion device 1 is a cylindrical component whose internal space is connected to the outside at the first opening 14 at the top and the second opening 15 at the bottom. The housing 10 has, for example, a first cylindrical portion 11, a second cylindrical portion 12, and a cylindrical reduced diameter portion 13 connecting the first cylindrical portion 11 and the second cylindrical portion 12. The shapes of the first cylindrical portion 11, the second cylindrical portion 12, and the reduced diameter portion 13 are, for example, cylindrical. The inner diameter of the first cylindrical portion 11 is larger than the inner diameter of the reduced diameter portion 13. The inner diameter of the reduced diameter portion 13 is larger than the inner diameter of the second cylindrical portion 12. The reduced diameter portion 13 may also have the shape of a truncated cone that reduces in diameter from the first cylindrical portion 11 toward the second cylindrical portion 12. In the housing 10, the first opening 14 is formed at the end of the first cylindrical portion 11, and the second opening 15 is formed at the end of the second cylindrical portion 12. The second opening 15 of the housing portion 10 is connected to an inlet 25 of the gear pump 2 described later.

[0084] The extrusion apparatus 1 further includes a lid 50. When the container 10 contains the resin composition 5, the first opening 14 of the container 10 is sealed by the lid 50. A pipe 56 is connected to the lid 50. Gas can be supplied to the container 10 via the pipe 56. The gas supplied to the container 10 is preferably an inert gas such as nitrogen. The pipe 56 is connected to, for example, a high-pressure gas cylinder, and the gas pressure can be adjusted by operating a pressure reducing valve.

[0085] The extruder 1 may further include a heater (not shown) for heating the resin composition 5 contained in the container 10 . The type and location of the heater are not particularly limited. As an example, the heater may be provided near the reduced diameter portion 13 of the container 10 .

[0086] For example, a rod-shaped resin composition 5 (preform) is inserted into the first cylindrical portion 11 of the container 10 through the first opening 14. The rod-shaped resin composition 5 is softened and can flow, for example, by heating. The softened resin composition 5 is squeezed out of the container 10, for example, by utilizing the pressure difference between the first opening 14 and the second opening 15. Specifically, by introducing gas into the container 10 from the first opening 14 and pressing the upper surface of the resin composition 5, the softened resin composition 5 moves to the reduced diameter portion 13 and the second cylindrical portion 12 and is squeezed out from the second opening 15. The resin composition 5 squeezed out from the second opening 15 is sent to the gear pump 2 through the inlet 25 of the gear pump 2. Figure 1shows a state where the softened resin composition 5 is extruded from the second opening 15. It should be noted that the heating temperature of the resin composition 5 can be appropriately set depending on the composition of the resin composition 5, and is, for example, 100° C. to 250° C. The viscosity μ of the resin composition 5 extruded from the extruder 1 is not particularly limited, and is, for example, 1 to 7000 Pa·s, preferably 500 to 7000 Pa·s, more preferably 5000 Pa·s or less, and even more preferably 3000 Pa·s or less.

[0087] The gear pump 2 has a housing 20 and one or more gears (for example, a pair of gears 21). Figure 1 2 shows the outer peripheral surface of one of the pair of gears 21. A flow path 24 through which the resin composition 5 flows is formed inside the housing 20. The pair of gears 21 are housed in the housing 20, and more specifically, the flow path 24 is disposed within the housing 20. In other words, a space is provided within the housing 20 for accommodating the pair of gears 21.

[0088] The gear pump 2 also has an inlet 25 and an outlet 26 for the resin composition 5. The inlet 25 is formed, for example, above the housing 20. The outlet 26 is formed, for example, below the housing 20. The flow path 24 extends from the inlet 25 of the housing 20 to the outlet 26. The resin composition 5 extruded from the extrusion device 1 is sent to the flow path 24 through the inlet 25 of the gear pump 2. After the resin composition 5 adjusts the flow rate through a pair of gears 21, it is sent out from the gear pump 2 through the outlet 26. In the present embodiment, the flow rate of the resin composition 5 sent out from the gear pump 2 is not particularly limited, for example, it is less than 20L / min, preferably less than 10mL / min, more preferably less than 1.0mL / min, further preferably less than 0.5mL / min, and particularly preferably less than 0.1mL / min. The lower limit of the flow rate of the resin composition 5 sent out from the gear pump 2 is not particularly limited, for example, it is 0.001mL / min. It should be noted that in an extrusion device equipped with a screw, it is generally difficult to adjust the flow rate of the extruded resin composition to a small value. Therefore, it is difficult to adjust the flow rate of the resin composition extruded from an extruder equipped with a screw to 1.0 mL / min or less even using a gear pump.

[0089] Figure 2Represents the side section of a pair of gears 21. A pair of gears 21, for example, include a driving gear 22 and a driven gear 23, and these gears 22 and 23 are meshed with each other. The gear pump 2 also has a driving shaft 27 connected to the driving gear 22, a driven shaft 28 connected to the driven gear 23, and a servo motor (not shown) connected to the driving shaft 27. By driving the servo motor, power is transmitted from the driving shaft 27 to the driving gear 22. Thus, the driving gear 22 rotates and the driven gear 23 also rotates. The flow rate of the resin composition 5 is adjusted by controlling the rotation of the gears 22 and 23. The rotation speed N of the driving gear 22 (or driven gear 23) is not particularly limited, for example, is controlled to be less than 100rpm, preferably controlled to be less than 30rpm, more preferably controlled to be less than 20rpm, further preferably controlled to be less than 15rpm, particularly preferably controlled to be less than 10rpm, and especially preferably controlled to be less than 5rpm. The lower limit value of the rotation speed N is not particularly limited, for example, is 0.1rpm.

[0090] The size and shape of the drive gear 22 can be the same as or different from those of the driven gear 23. The diameter D of the side surface of the drive gear 22 (or driven gear 23) is not particularly limited and is, for example, 80 mm or less, preferably 30 mm or less, more preferably 25 mm or less, further preferably 20 mm or less, and particularly preferably 15 mm or less. The lower limit of the diameter D is not particularly limited and is, for example, 5 mm. In this specification, the "diameter of the side surface of the gear" refers to the diameter of the smallest circle that can enclose the outer periphery of the side surface of the gear.

[0091] It is preferable that the teeth 22 a (or teeth 23 a ) included in the driving gear 22 (or driven gear 23 ) does not come into contact with the housing 20 when the driving gear 22 (or driven gear 23 ) rotates. Figure 3It is an enlarged view near the front end of the tooth portion 22a of the drive gear 22. The distance (top gap) TC between the tooth portion 22a of the drive gear 22 (or the tooth portion 23a of the driven gear 23) and the housing 20 is not particularly limited, and is, for example, 5 μm or more, preferably 10 μm or more, more preferably 30 μm or more, further preferably 50 μm or more, particularly preferably 80 μm or more, and especially preferably 100 μm or more. In this specification, the top gap TC can be the design value of the distance between the tooth portion of the gear and the housing, or it can be the minimum value of the distance. The larger the top gap TC, the more it tends to reduce the shear stress generated in the resin composition 5 between the tooth portion 22a (or tooth portion 23a) and the housing 20. If the shear stress generated in the resin composition 5 is reduced, it can prevent the tooth portion 22a (or tooth portion 23a) and the housing 20 from being ground when the drive gear 22 (or driven gear 23) rotates. In other words, the larger the top gap TC, the more it is possible to suppress the material of the gears 22 and 23 or the housing 20 from mixing into the resin composition 5. From the perspective of fully maintaining the efficiency of the gear pump 2 and fully ensuring the function of regulating the flow rate of the resin composition 5, the upper limit of the top gap TC is preferably 200 μm.

[0092] Figure 4 The side surfaces 22b and 22c of the driving gear 22 and the side surfaces 23b and 23c of the driven gear 23 are shown in FIG. 1 and 2. The side surfaces 22b and 22c of the driving gear 22 are opposite to each other. The side surfaces 23b and 23c of the driven gear 23 are also opposite to each other. Figure 4 As shown, it is preferred that the side surfaces 22 b and 22 c of the driving gear 22 (or the side surfaces 23 b and 23 c of the driven gear 23 ) do not contact the housing 20 .

[0093] The distance (backlash) SC1 between the side surface 22b of the drive gear 22 (or the side surface 23b of the driven gear 23) and the housing 20 (specifically, the inner wall of the housing 20 facing the side surface 22b) is not particularly limited, and is, for example, 5 μm or greater, preferably 10 μm or greater, more preferably 30 μm or greater, further preferably 50 μm or greater, particularly preferably 80 μm or greater, and particularly preferably 100 μm or greater. A larger backlash SC1 tends to reduce the shear stress generated in the resin composition 5 between the side surface 22b of the drive gear 22 (or the side surface 23b of the driven gear 23) and the housing 20. Reducing the shear stress generated in the resin composition 5 can prevent the side surface 22b (or side surface 23b) and the housing 20 from being worn away during rotation of the drive gear 22 (or driven gear 23). In other words, a larger backlash SC1 prevents the material of the gears 22, 23, or the housing 20 from mixing into the resin composition 5. From the viewpoint of sufficiently maintaining the efficiency of the gear pump 2 and sufficiently ensuring the function of regulating the flow rate of the resin composition 5 , the upper limit of the backlash SC1 is preferably 200 μm.

[0094] The distance (side clearance) SC2 between the side surface 22c of the driving gear 22 (or the side surface 23c of the driven gear 23) and the housing 20 (specifically, the inner wall of the housing 20 opposite to the side surface 22c) may be the same as or different from the side clearance SC1. The side clearance SC2 is, for example, greater than 5 μm, preferably greater than 10 μm, more preferably greater than 30 μm, further preferably greater than 50 μm, particularly preferably greater than 80 μm, and particularly preferably greater than 100 μm. The upper limit value of the side clearance SC2 is preferably 200 μm. In this specification, the side clearances SC1 and SC2 may be the design values ​​of the distance between the side surface of the gear and the housing, or may be the minimum values ​​of the distance. In this specification, the smallest side clearance of the two side clearances SC1 and SC2 is sometimes referred to as simply "side clearance SC".

[0095] In the present embodiment, for one gear (gear 22 or 23) in the pair of gears 21, it is preferred that at least one of the top clearance TC and the side clearance SC is selected from 5 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more. In addition, for both gears 22 and 23, it is preferred that at least one of the top clearance TC and the side clearance SC is selected from 5 μm or more, particularly preferably 30 μm or more. As far as the inventors know, among gear pumps that adjust the flow rate of a fluid to less than 1.0 mL / min, a gear pump in which either the top clearance TC or the side clearance SC is greater than 30 μm is not known so far. This gear pump is particularly suitable for use in a manufacturing device for plastic optical fibers.

[0096] In this embodiment, the maximum value of the shear stress generated in the resin composition 5 between the tooth portion (tooth portion 22a or 23a) of one gear (gear 22 or 23) of the pair of gears 21 and the housing 20 is represented by τ TC Specifically, the maximum value of the shear stress generated in the resin composition 5 between the tooth portion of the gear 21 with the smallest top clearance TC and the housing 20 is expressed as τ TC (kPa). In addition, the maximum value of the shear stress generated in the resin composition 5 between the side surface of the gear and the housing 20 is represented as τ SC Specifically, the maximum value of the shear stress generated in the resin composition 5 between the side with the smaller backlash of the two side surfaces of the gear and the housing 20 is represented by τ SC (kPa). About τ SC and τ TC , preferably satisfying the following relationship (I).

[0097] τ SC ≤-τ TC +1200 (I)

[0098] Maximum shear stress τ TC (kPa) can be calculated by the following formula (i). In formula (i), μ is the viscosity of the resin composition 5 (Pa·s), D is the diameter of the side of the gear (mm), N is the rotation speed of the gear (rpm), π is the circumference, and TC is the top clearance (μm).

[0099]

Mathematical formula 1

[0100]

[0101] Maximum shear stress τ TC For example, it is 1000 kPa or less, preferably 800 kPa or less, more preferably 500 kPa or less, further preferably 400 kPa or less, and particularly preferably 100 kPa or less.

[0102] Maximum shear stress τ SC (kPa) can be calculated by the following formula (ii). In formula (ii), μ, D, N, and π are the same as those in formula (i). SC is the backlash (μm).

[0103]

Mathematical formula 2

[0104]

[0105] Maximum shear stress τ SC For example, it is 1000 kPa or less, preferably 800 kPa or less, more preferably 500 kPa or less, further preferably 400 kPa or less, and particularly preferably 100 kPa or less.

[0106] About τ SC and τ TC When the above relational expression (I) is satisfied, grinding of the pair of gears 21 or the housing 20 can be sufficiently suppressed when the pair of gears 21 are driven. Therefore, when the pair of gears 21 are driven, impurities such as metal can be sufficiently suppressed from being mixed into the resin composition 5.

[0107] That is, the present invention, from another aspect, provides a device for manufacturing a plastic optical fiber, comprising:

[0108] an extrusion device that extrude the resin composition; and

[0109] a gear pump that adjusts the flow rate of the resin composition extruded from the extrusion device,

[0110] The gear pump comprises a housing through which a resin composition passes and a pair or more of gears housed in the housing and meshing with each other.

[0111] The maximum value of the shear stress generated in the resin composition between the tooth portion of one of the pair of gears and the housing is represented by τ TC (kPa), and the maximum value of the shear stress generated in the resin composition between the side surface of the gear and the housing is represented as τ SC (kPa), the following relational formula (I) is satisfied.

[0112] τ SC ≤-τ TC +1200 (I)

[0113] In addition, the present invention provides a gear pump from another aspect thereof, which comprises a housing through which a fluid (such as a resin composition) passes and a pair or more of gears housed in the housing and meshing with each other.

[0114] The maximum value of the shear stress generated in the fluid between the tooth portion of one of the pair of gears and the housing is expressed as τ TC (kPa), and the maximum value of the shear stress generated in the fluid between the side of the gear and the housing is expressed as τ SC (kPa), the following relational expression (I) is satisfied. Such a gear pump can suppress the mixing of impurities into the fluid and stably discharge the fluid at a target flow rate.

[0115] τ SC ≤-τ TC +1200 (I)

[0116] Regarding the above τ SC and τ TC , more preferably, the following relational expression (II) is satisfied. When the following relational expression (II) is satisfied, it is possible to further suppress the mixing of impurities such as metal into the resin composition 5 when the pair of gears 21 are driven.

[0117] τ SC ≤-τ TC +500 (II)

[0118] When the above-mentioned relational expression (I) or (II) is satisfied, there is a tendency to sufficiently suppress the increase in the metal concentration in the resin composition 5 before and after passing through the gear pump 2. The increase in the metal concentration in the resin composition 5 before and after passing through the gear pump 2 is, for example, 300 mass ppm or less, preferably 250 mass ppm or less, more preferably 200 mass ppm or less, and even more preferably 100 mass ppm or less. Depending on the circumstances, it may be 5 mass ppb or less, 3 mass ppb or less, 1.5 mass ppb or less, or 1 mass ppb or less.

[0119] It should be noted that the above-mentioned τ can be reduced by reducing the viscosity of the resin composition 5 and the rotation speed of the gear. SC and τ TC However, if the viscosity of the resin composition 5 is too low, it may be difficult to form the resin composition 5 sent from the gear pump 2 into a fibrous shape. If the rotation speed of the gear is too low, the flow rate of the resin composition 5 sent from the gear pump 2 may fluctuate. In contrast, with respect to the top clearance TC and the side clearance SC, it is appropriate to adjust the above-mentioned τ SC and τ TC Adjust to a smaller value.

[0120] As described above, the resin composition 5 whose flow rate is adjusted by the pair of gears 21 is delivered from the outlet 26 of the gear pump 2 through the flow path 24. The resin composition 5 passing through the outlet 26 moves vertically downward, for example, and is formed into fibers.

[0121] The molded article produced by the manufacturing apparatus 100 is typically a single-layer fiber that becomes the core of the POF. The diameter of the fibrous molded article is, for example, 300 μm or less, preferably 200 μm or less, and more preferably 150 μm or less. The lower limit of the diameter of the molded article is, for example, 10 μm. The diameter of the molded article can be adjusted by the diameter of the outlet 26, the flow rate of the resin composition 5 delivered from the gear pump 2, the winding speed of the molded article, and the like.

[0122] In addition to the extruder 1 and the gear pump 2, the manufacturing device 100 may also include a controller (not shown). The controller is, for example, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an arithmetic circuit, a storage device, etc. The controller stores a program for properly operating the manufacturing device 100. Specifically, the controller controls the drive of the servo motor of the gear pump 2. The controller can control the heater provided by the extruder 1.

[0123] In the manufacturing apparatus 100, it is preferred that at least the portion in contact with the resin composition 5 be made of a material having corrosion resistance to the resin composition 5. In this specification, "corrosion resistance" means that the material is hardly corroded when in contact with the resin composition 5. For example, it means that when the material is in contact with the resin composition 5 and heated at 300°C for 100 hours, the contact portion is less corroded per 1 cm. 2The amount of the material dissolved into the resin composition 5 is less than 1 μg / g. By making the portion in contact with the resin composition 5 from a corrosion-resistant material, it is possible to further suppress the mixing of impurities such as metals into the resin composition 5. The material that is corrosion-resistant to the resin composition 5 includes, for example, at least one selected from Hastelloy and Stellite. It should be noted that Hastelloy is an alloy containing nickel as a main component and also containing molybdenum, chromium, etc. Stellite is an alloy containing cobalt as a main component and also containing chromium, tungsten, etc. "Main component" refers to the component with the largest mass ratio in the alloy mentioned.

[0124] In the manufacturing apparatus 100, examples of portions that come into contact with the resin composition 5 include the inner side surfaces of the housing 10 of the extruder 1, the inner side surfaces of the housing 20 of the gear pump 2, and the surfaces of the pair of gears 21. In particular, in this embodiment, the inner side surfaces of the housing 20 of the gear pump 2 and the surfaces of the pair of gears 21 are preferably made of a material that is resistant to corrosion by the resin composition 5. These surfaces are achieved, for example, by coating or thin layers made of a material that is resistant to corrosion by the resin composition 5.

[0125] The housing 10 of the extruder 1, the housing 20 of the gear pump 2, and the pair of gears 21 can all be made of a material that is corrosion-resistant to the resin composition 5. The content of Hastelloy or Stellite in the housing 10 is, for example, 50% by mass or greater, preferably 80% by mass or greater, and more preferably 90% by mass or greater. The housing 10 can be substantially made of Hastelloy or Stellite.

[0126] Similarly, the content of Hastelloy or Stellite in the housing 20 is, for example, 50% by mass or greater, preferably 80% by mass or greater, and more preferably 90% by mass or greater. The housing 20 may be substantially composed of Hastelloy or Stellite. The content of Hastelloy or Stellite in the pair of gears 21 is, for example, 50% by mass or greater, preferably 80% by mass or greater, and more preferably 90% by mass or greater. The pair of gears 21 may be substantially composed of Hastelloy or Stellite.

[0127] In this embodiment, the resin composition 5 is preferably a composition suitable for the core of the POF. The resin composition 5 includes, for example, a fluorinated polymer (polymer (P)). From the perspective of suppressing light absorption based on the stretching energy of the C-H bond, the polymer (P) preferably does not substantially contain hydrogen atoms, and it is particularly preferred that all hydrogen atoms bonded to carbon atoms are replaced by fluorine atoms. In this specification, the polymer (P) does not substantially contain hydrogen atoms means that the content of hydrogen atoms in the polymer (P) is 1 mol% or less.

[0128] The polymer (P) preferably has a fluorinated aliphatic ring structure. The fluorinated aliphatic ring structure may be contained in the main chain of the polymer (P) or in a side chain of the polymer (P). For example, the polymer (P) has a structural unit (A) represented by the following formula (1).

[0129]

Chemical Formula 3

[0130]

[0131] In formula (1), R ff 1 ~R ff 4 Each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms, or a perfluoroalkyl ether group having 1 to 7 carbon atoms. ff 1 With R ff 2 They can be linked to form a ring. "Perfluoro" means that all hydrogen atoms bonded to carbon atoms are replaced by fluorine atoms. In formula (1), the number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1. The perfluoroalkyl group may be linear or branched. Examples of the perfluoroalkyl group include trifluoromethyl, pentafluoroethyl, and heptafluoropropyl.

[0132] In formula (1), the carbon number of the perfluoroalkyl ether group is preferably 1 to 5, more preferably 1 to 3. The perfluoroalkyl ether group may be linear or branched. Examples of the perfluoroalkyl ether group include perfluoromethoxymethyl.

[0133] R ff 1 With R ff 2 When they are linked to form a ring, the ring may be a five-membered ring or a six-membered ring. Examples of the ring include a perfluorotetrahydrofuran ring, a perfluorocyclopentane ring, and a perfluorocyclohexane ring.

[0134] Specific examples of the structural unit (A) include structural units represented by the following formulae (A1) to (A8).

[0135]

Chemical Formula 4

[0136]

[0137] The structural unit (A) is preferably the structural unit (A2) among the structural units represented by the above formulae (A1) to (A8), that is, the structural unit represented by the following formula (2).

[0138]

Chemical Formula 5

[0139]

[0140] Polymer (P) can include one or more structural units (A). In polymer (P), the content of structural unit (A) is preferably 20 mol% or more relative to the total of all structural units, more preferably 40 mol% or more. By including more than 20 mol% of structural units (A), polymer (P) has a trend of having higher heat resistance. When including more than 40 mol% of structural units (A), polymer (P) has a trend of having higher transparency and high mechanical strength in addition to having high heat resistance. In polymer (P), the content of structural unit (A) is preferably less than 95 mol% relative to the total of all structural units, more preferably less than 70 mol%.

[0141] The structural unit (A) is derived from, for example, a compound represented by the following formula (3). In formula (3), R ff 1 ~R ff 4 The same as formula (1). The compound represented by formula (3) can be obtained by a known production method such as the production method disclosed in JP-A-2007-504125.

[0142]

Chemical Formula 6

[0143]

[0144] Specific examples of the compound represented by the above formula (3) include compounds represented by the following formulas (M1) to (M8).

[0145]

Chemical Formula 7

[0146]

[0147] The polymer (P) may contain other structural units in addition to the structural unit (A). Examples of the other structural units include the following structural units (B) to (D).

[0148] The structural unit (B) is represented by the following formula (4).

[0149]

Chemical Formula 8

[0150]

[0151] In formula (4), R 1 ~R 3 Each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. 4represents a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group may have a ring structure. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms.

[0152] The polymer (P) may contain one or more structural units (B). In the polymer (P), the content of the structural unit (B) is preferably 5 to 10 mol% relative to the total of all structural units. The content of the structural unit (B) may be 9 mol% or less, or 8 mol% or less.

[0153] The structural unit (B) is derived from, for example, a compound represented by the following formula (5). In formula (5), R 1 ~R 4 The same as formula (4). The compound represented by formula (5) is a fluorine-containing vinyl ether such as perfluorovinyl ether.

[0154]

Chemical Formula 9

[0155]

[0156] The structural unit (C) is represented by the following formula (6).

[0157]

Chemical Formula 10

[0158]

[0159] In formula (6), R 5 ~R 8 Each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms. The perfluoroalkyl group may have a ring structure. Some of the fluorine atoms may be substituted with halogen atoms other than fluorine atoms. Some of the fluorine atoms in the perfluoroalkyl group may be substituted with halogen atoms other than fluorine atoms.

[0160] The polymer (P) may contain one or more structural units (C). In the polymer (P), the content of the structural unit (C) is preferably 5 to 10 mol% relative to the total of all structural units. The content of the structural unit (C) may be 9 mol% or less, or 8 mol% or less.

[0161] The structural unit (C) is derived from, for example, a compound represented by the following formula (7). In formula (7), R 5 ~R 8 The same as formula (6). The compound represented by formula (7) is a fluorine-containing olefin such as tetrafluoroethylene and chlorotrifluoroethylene.

[0162]

Chemical Formula 11

[0163]

[0164] The structural unit (D) is represented by the following formula (8).

[0165]

Chemical Formula 12

[0166]

[0167] In formula (8), Z represents an oxygen atom, a single bond or -OC(R 19 R 20 )O-,R 9 ~R 20 Each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms, or a perfluoroalkoxy group having 1 to 5 carbon atoms. A portion of the fluorine atoms may be substituted by a halogen atom other than a fluorine atom. A portion of the fluorine atoms in the perfluoroalkyl group may be substituted by a halogen atom other than a fluorine atom. A portion of the fluorine atoms in the perfluoroalkoxy group may be substituted by a halogen atom other than a fluorine atom. s and t each independently represent an integer from 0 to 5, and s+t represents an integer from 1 to 6 (wherein Z is -OC(R 19 R 20 )O-, s+t can be 0).

[0168] The structural unit (D) is preferably represented by the following formula (9). The structural unit represented by the following formula (9) is the case where Z is an oxygen atom, s is 0, and t is 2 in the above formula (8).

[0169]

Chemical Formula 13

[0170]

[0171] In formula (9), R 141 、R 142 、R 151 and R 152 Each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms, or a perfluoroalkoxy group having 1 to 5 carbon atoms. A portion of the fluorine atoms may be substituted with a halogen atom other than a fluorine atom. A portion of the fluorine atoms in the perfluoroalkyl group may be substituted with a halogen atom other than a fluorine atom. A portion of the fluorine atoms in the perfluoroalkoxy group may be substituted with a halogen atom other than a fluorine atom.

[0172] The polymer (P) may contain one or more structural units (D). In the polymer (P), the content of the structural unit (D) is preferably 30 to 67 mol% relative to the total of all structural units. The content of the structural unit (D) is, for example, 35 mol% or more, 60 mol% or less, or 55 mol% or less.

[0173] The structural unit (D) is derived from, for example, a compound represented by the following formula (10). In formula (10), Z, R 9 ~R 18, s and t are the same as those in formula (8). The compound represented by formula (10) is a fluorine-containing compound having two or more polymerizable double bonds and capable of cyclopolymerization.

[0174]

Chemical Formula 14

[0175]

[0176] The structural unit (D) is preferably derived from a compound represented by the following formula (11). In formula (11), R 141 、R 142 、R 151 and R 152 Same as formula (9).

[0177]

Chemical Formula 15

[0178]

[0179] Specific examples of the compound represented by formula (10) or formula (11) include the following compounds.

[0180] CF2=CFOCF2CF=CF2

[0181] CF2=CFOCF(CF3)CF=CF2

[0182] CF2=CFOCF2CF2CF=CF2

[0183] CF2=CFOCF2CF(CF3)CF=CF2

[0184] CF2=CFOCF(CF3)CF2CF=CF2

[0185] CF2=CFOCFClCF2CF=CF2

[0186] CF2=CFOCCl2CF2CF=CF2

[0187] CF2=CFOCF2OCF=CF2

[0188] CF2=CFOC(CF3)2OCF=CF2

[0189] CF2=CFOCF2CF(OCF3)CF=CF2

[0190] CF2=CFCF2CF=CF2

[0191] CF2=CFCF2CF2CF=CF2

[0192] CF2=CFCF2OCF2CF=CF2

[0193] CF2=CFOCF2CFClCF=CF2

[0194] CF2=CFOCF2CF2CCl=CF2

[0195] CF2=CFOCF2CF2CF=CFCl

[0196] CF2=CFOCF2CF(CF3)CCl=CF2

[0197] CF2=CFOCF2OCF=CF2

[0198] CF2=CFOCCl2OCF=CF2

[0199] CF2=CClOCF2OCCl=CF2

[0200] The polymer (P) may further contain other structural units in addition to the structural units (A) to (D), but preferably contains substantially no other structural units in addition to the structural units (A) to (D). The phrase "the polymer (P) contains substantially no other structural units in addition to the structural units (A) to (D)" means that the total amount of the structural units (A) to (D) relative to the total amount of all the structural units in the polymer (P) is 95 mol% or more, preferably 98 mol% or more.

[0201] The polymerization method of the polymer (P) is not particularly limited, and for example, a common polymerization method such as free radical polymerization can be used. The polymerization initiator used for polymerizing the polymer (P) may be a perfluorinated compound.

[0202] The glass transition temperature (Tg) of the polymer (P) is not particularly limited, and is, for example, 100°C to 140°C, may be 105°C or higher, or may be 120°C or higher. In this specification, Tg refers to the midpoint glass transition temperature (Tg) determined in accordance with JIS K7121:1987. mg ).

[0203] The resin composition 5 may contain the polymer (P) as a main component, and is preferably substantially composed of the polymer (P). The resin composition 5 may further contain additives such as a refractive index adjuster. The resin composition 5 is solid at room temperature (25° C.), for example.

[0204] In this embodiment, the resin composition 5 is extruded by gas in the extrusion device 1. Therefore, impurities such as metal are not easily mixed into the resin composition 5 extruded from the extrusion device 1. The increase in the metal concentration in the resin composition 5 before and after passing through the manufacturing device 100 is, for example, 200 mass ppm or less, preferably 100 mass ppm or less, and depending on the circumstances, can be 100 mass ppb or less, 50 mass ppb or less, 10 mass ppb or less, or 5 mass ppb or less. In this way, in the manufacturing device 100 of this embodiment, the mixing of metals, which causes an increase in the transmission loss of the plastic optical fiber, can be suppressed.

[0205] In the present embodiment, the flow rate of the resin composition 5 is regulated by a gear pump 2. Therefore, even when the flow rate of the resin composition 5 extruded from the extrusion device 1 changes, the flow rate of the resin composition 5 can be made almost constant by the gear pump 2. Since the change in the flow rate of the resin composition 5 can be suppressed, the manufacturing device 100 is suitable for adjusting the thickness of the fibrous formed body to be uniform. The change in the outer diameter (diameter) of the fibrous formed body made by the manufacturing device 100 is, for example, less than 5%, preferably less than 3%, and more preferably less than 1%. In this specification, the change in the outer diameter of the formed body refers to the ratio (3σ / Ave.) of three times the standard deviation of the outer diameter (3σ) to the average value (Ave.) of the outer diameter. The outer diameter of the formed body can be measured using a commercially available displacement meter.

[0206] (Implementation Method 2)

[0207] The manufacturing apparatus 100 of the first embodiment may further include a device for coating the side surface of the fibrous molded body with another resin composition different from the resin composition 5 constituting the molded body. Figure 5 As shown, the manufacturing device 110 of this embodiment 2 is equipped with a plurality of extrusion devices 1b and 3 and a plurality of gear pumps 2b and 2c in addition to the extrusion device 1 (1a) and gear pump 2 (2a) described in the embodiment 1 above. The manufacturing device 110 also includes a first chamber 40 and a second chamber 41. The first chamber 40 and the second chamber 41 are arranged in sequence below in the vertical direction. The molded body (resin composition 5) sent out from the gear pump 2a and formed into a fibrous shape is sequentially supplied to the first chamber 40 and the second chamber 41.

[0208] The extrusion device 1b includes, for example, a housing 10b for housing a resin composition 6 having a composition suitable for the cladding layer of a POF. The extrusion device 1b described above for the extrusion device 1 of Embodiment 1 can be used. In the extrusion device 1b, by introducing a gas into the housing 10b, the resin composition 6 can be extruded from the housing 10b.

[0209] The resin composition 6 extruded from the extruder 1b is fed to the gear pump 2b. As the gear pump 2b, the gear pump described above for the gear pump 2 of Embodiment 1 can be used. The gear pump 2b adjusts the flow rate of the resin composition 6 extruded from the extruder 1b.

[0210] The resin composition 6 delivered from the gear pump 2b is supplied to the first chamber 40. In the first chamber 40, the fibrous molded body is coated with the resin composition 6, thereby forming a cladding layer covering the outer periphery of the molded body. The molded body coated with the cladding layer moves from the first chamber 40 to the second chamber 41.

[0211] The extrusion device 3 includes, for example, a container 30 for containing a resin composition 7 having a composition suitable for a coating layer (upper cladding layer) of POF, a screw 31 disposed in the container 30, and a hopper 32 connected to the container 30. In the extrusion device 3, the granular resin composition 7 is supplied to the container 30 via the hopper 32. The granular resin composition 7 supplied to the container 30 is softened and made flowable by, for example, being kneaded while being heated by the screw 31. The softened resin composition 7 is extruded from the container 30 via the screw 31.

[0212] The resin composition 7 extruded from the extruder 3 is fed to the gear pump 2 c. As the gear pump 2 c, the gear pump described above for the gear pump 2 of Embodiment 1 can be used. The gear pump 2 c adjusts the flow rate of the resin composition 7 extruded from the extruder 3 .

[0213] The resin composition 7 sent out from the gear pump 2c is supplied to the second chamber 41. In the second chamber 41, by coating the cladding with the resin composition 7, a coating layer covering the outer periphery of the cladding layer can be formed. It should be noted that the resin composition 7 is extruded by the extrusion device 3 equipped with a screw 31. Therefore, the coating layer formed by the resin composition 7 sometimes includes metal from the extrusion device 3. However, in POF, the light from the core hardly reaches the coating layer. Therefore, even if the coating layer includes metal, the transmission loss of POF hardly increases.

[0214] The refractive index of the resin composition 6 forming the POF cladding layer is preferably lower than that of the core-forming resin composition 5. Examples of the resin material contained in the resin composition 6 include fluorine-containing resins, acrylic resins such as methyl methacrylate, styrene resins, and carbonate resins. Examples of the resin material contained in the resin composition 7 forming the POF coating layer include polycarbonate, various engineering plastics, cycloolefin polymers, PTFE, modified PTFE, and PFA.

[0215] It should be noted that a molded article having a three-layer structure of a core, a cladding, and a coating was produced in the manufacturing apparatus 110. However, the structure of the molded article produced by the manufacturing apparatus 110 is not limited to a three-layer structure. The molded article may also have a two-layer structure consisting of a core and a cladding.

[0216] Example

[0217] Hereinafter, the present invention will be described in further detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0218] (Measurement Example 1)

[0219] First, a gear pump having a housing and a pair of gears is prepared. The size and shape of the pair of gears are the same as each other. Regarding the pair of gears, the minimum value of the distance between the tooth portion of the gear and the housing (top clearance) TC is 100 μm. The minimum value of the distance between the side of the gear and the housing (side clearance) SC is 110 μm. The diameter of the side of the gear is 12 mm. The housing and the pair of gears are composed of Stellite alloy as a whole. The Stellite alloy constituting the gear pump contains cobalt as a main component and does not contain iron.

[0220] Silicone oil was allowed to flow through the gear pump, and the increase in cobalt concentration in the silicone oil before and after passing through the gear pump was measured. The speed of the gears in the gear pump was adjusted to 10 rpm. The viscosity of the silicone oil was 1000 Pa·s. The maximum shear stress τ generated in the silicone oil between the gear teeth and the housing was set to TC (kPa), the maximum value of the shear stress generated in the silicone oil between the side of the gear and the housing, τ SC Table 1 shows the pressure (kPa) and the increase in the cobalt concentration in the silicone oil before and after passing through the gear pump.

[0221] (Measurement Examples 2 to 18)

[0222] The increase in the cobalt concentration in the silicone oil before and after passing through the gear pump was measured using the same method as in Example 1, except that the top clearance TC, side clearance SC, diameter D of the side of the gear, gear rotational speed N, and viscosity μ of the silicone oil in the gear pump were changed to the values ​​shown in Table 1.

[0223]

Table 1

[0224]

[0225] Figure 6 is the maximum value τ of the shear stress in Measurement Examples 1 to 18 TC and τ SC According to Table 1 and Figure 6 It can be seen that when the relationship (I)(τ SC ≤-τ TCIn the gear pumps of measurement examples 1 to 13 with a flow rate of 1200, the increase in the concentration of cobalt in the silicone oil before and after passing through the gear pump was suppressed compared to the gear pumps of measurement examples 14 to 18. In particular, in the case where the relationship (II) (τ SC ≤-τ TC +500) in the gear pumps of measurement examples 1 to 7, the increase in the concentration of cobalt in the silicone oil was further suppressed. Figure 6 In the table, ○ indicates a measurement example where the increase in cobalt concentration was 1 ppb or less. △ indicates a measurement example where the increase in cobalt concentration exceeded 1 ppb and was 5 ppb or less. × indicates a measurement example where the increase in cobalt concentration exceeded 5 ppb.

[0226] (Example 1)

[0227] A production apparatus equipped with an extruder capable of extruding the resin composition using gas and the gear pump used in Measurement Example 1 was prepared (see Figure 1 The resin composition was extruded using a gas extruder. Furthermore, the flow rate of the extruded resin composition was adjusted using a gear pump. The resin composition was composed of polycarbonate. Prior to extrusion from the extruder, the resin composition was heated to 240°C. The viscosity of the heated resin composition was 2000 Pa·s. The flow rate of the resin composition delivered from the gear pump was 5.9 mL / min. The extruder was constructed of iron.

[0228] Next, the resin composition delivered from the gear pump was taken up while cooling and formed into a fiber. The winding speed of the resin composition was 30 m / min. The outer diameter of the formed body was adjusted to 0.5 mm.

[0229] For the fibrous formed body, before arriving at the winding bobbin, a displacement meter (LS-9006M made by Keyence) is used to measure its outer diameter. The measuring time of the outer diameter is 0.1 seconds, and the measuring position is 50,000. Based on the obtained result, the variation of the outer diameter (3σ / Ave.) is calculated. In addition, the increase in the metal concentration in the resin composition before and after the manufacturing device is measured. The results are shown in Table 2.

[0230] (Comparative Example 1)

[0231] A fibrous molded body was obtained by the same method as in Example 1, except that the production apparatus did not include a gear pump and the resin composition extruded from the extruder was molded into a fibrous form. Furthermore, the change in the outer diameter of the molded body (3σ / Ave.) and the increase in the metal concentration in the resin composition before and after passing through the production apparatus were determined by the same method as in Example 1.

[0232] (Comparative Example 2)

[0233] As an extrusion device, except using a single screw extruder equipped with a screw, a fibrous molded body was obtained by the same method as in Example 1. The single screw extruder was made of chromium-molybdenum steel (SCM435). SCM435 contains iron as a main component and does not contain cobalt. In addition, the variation (3σ / Ave.) of the outer diameter of the molded body and the increase in the metal concentration in the resin composition before and after the manufacturing device were determined by the same method as in Example 1.

[0234]

Table 2

[0235]

[0236] As apparent from Table 2, the production apparatus of Example 1 including an extruder capable of extruding the resin composition using gas and a gear pump can suppress the incorporation of metal into the resin composition and can be formed into fibers having uniform thickness.

[0237] Industrial applicability

[0238] The manufacturing apparatus of this embodiment is suitable for manufacturing POF.

Claims

1. A method for manufacturing a plastic optical fiber, the method comprising: The manufacturing device comprises: an extrusion device having a housing portion for housing a resin composition, wherein a gas is introduced into the housing portion to extrude the resin composition from the housing portion using the gas; and a gear pump that adjusts the flow rate of the resin composition extruded from the extrusion device, The manufacturing method includes the step of passing the resin composition extruded from the extrusion device through the gear pump, The gear pump includes a housing through which the resin composition passes and a pair or more of gears housed in the housing and meshing with each other. The maximum value of the shear stress generated in the resin composition between the tooth portion of one of the pair of or more gears and the housing is represented by τ. TC , the maximum value of the shear stress generated in the resin composition between the side surface of the gear and the housing is expressed as τ SC When , the following relationship (I) is satisfied, t SC ≤-τ TC +1200 (I), The τ TC and the τ SC The unit is kPa.

2. The method for manufacturing a plastic optical fiber according to claim 1, wherein: At least one selected from the distance between the tooth portion of the gear and the housing and the distance between the side surface of the gear and the housing is 5 μm or more.

3. The method for manufacturing a plastic optical fiber according to claim 1, wherein: The diameter of the side surface of the gear is 80 mm or less.

4. The method for manufacturing a plastic optical fiber according to claim 1, wherein: The rotation speed of the gear is below 100 rpm.

5. The method for manufacturing a plastic optical fiber according to claim 1, wherein: The inner side surface of the housing is made of a material having corrosion resistance to the resin composition.

6. The method for manufacturing a plastic optical fiber according to claim 1, wherein: Surfaces of the one or more gears are made of a material having corrosion resistance to the resin composition.

7. The method for manufacturing a plastic optical fiber according to claim 5 or 6, wherein: The material includes at least one selected from Hastelloy and Stellite.

8. The method for manufacturing a plastic optical fiber according to claim 1, wherein: The manufacturing method includes the step of extruding the resin composition from the extrusion device, The viscosity of the resin composition extruded from the extruder is 1 Pa·s to 7000 Pa·s.

9. The method for manufacturing a plastic optical fiber according to claim 1, wherein: The manufacturing method includes the step of sending the resin composition out from the gear pump, The flow rate of the resin composition delivered from the gear pump is 20 L / min or less.

10. The method for manufacturing a plastic optical fiber according to claim 1, wherein: An increase in the metal concentration in the resin composition before and after passing through the gear pump is 100 ppm by mass or less.

11. The method for manufacturing a plastic optical fiber according to claim 1, wherein: A plastic optical fiber is produced using the resin composition containing a polymer having a structural unit represented by the following formula (1). In the formula (1), R ff 1 ~R ff 4 Each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms, or a perfluoroalkyl ether group having 1 to 7 carbon atoms, and R ff 1 With R ff 2 They are optionally linked to form a ring.

12. The method for manufacturing a plastic optical fiber according to claim 1, wherein: The manufacturing method includes the step of shaping the resin composition delivered from the gear pump into a fiber shape.

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