CA1222854A - Process and apparatus for production of plastic optical fiber - Google Patents
Process and apparatus for production of plastic optical fiberInfo
- Publication number
- CA1222854A CA1222854A CA000450103A CA450103A CA1222854A CA 1222854 A CA1222854 A CA 1222854A CA 000450103 A CA000450103 A CA 000450103A CA 450103 A CA450103 A CA 450103A CA 1222854 A CA1222854 A CA 1222854A
- Authority
- CA
- Canada
- Prior art keywords
- cylinder
- optical fiber
- monomer
- core
- polymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/02—Permanent magnets [PM]
- H01F7/0231—Magnetic circuits with PM for power or force generation
- H01F7/0252—PM holding devices
- H01F7/0263—Closures, bags, bands, engagement devices with male and female parts
Abstract
Abstract:
A plastic optical fiber having low attenuation of light transmission and good mechanical properties is produced by a process which comprises filtering a monomer composition comprising a purified monomer, a polymeriza-tion initiator and a chain transfer agent through a filter made of a porous material; polymerizing the filtered monomer composition substantially free from optically foreign substances in an atmosphere of inert gas in a cylinder with stirring; discontinuing the stirring when the polymerization mixture becomes viscous and completing the polymerization without stirring; heating the polymer at a temperature not lower than its softening point while removing volatile components; transferring the polymer to a spinning head connected to one end of the cylinder to form a fiber core and simultaneously forming a cladding on the periphery of the core; and drawing the optical fiber.
A plastic optical fiber having low attenuation of light transmission and good mechanical properties is produced by a process which comprises filtering a monomer composition comprising a purified monomer, a polymeriza-tion initiator and a chain transfer agent through a filter made of a porous material; polymerizing the filtered monomer composition substantially free from optically foreign substances in an atmosphere of inert gas in a cylinder with stirring; discontinuing the stirring when the polymerization mixture becomes viscous and completing the polymerization without stirring; heating the polymer at a temperature not lower than its softening point while removing volatile components; transferring the polymer to a spinning head connected to one end of the cylinder to form a fiber core and simultaneously forming a cladding on the periphery of the core; and drawing the optical fiber.
Description
8~4 PROCESS AND APPAE~ATUS FOR PRODUC~ION Ol~
PLASTIC OPTICAL FIBER
FIELD OE` THE INVENTION
The present invention relates to a process and an apparatus for the production of a plastic optical fiber having low attenuation of light transmission and good mechanical properties.
B~CKGROUND OF ~E INVENTION
U.S. Patent No. 3,993,834 and Japanese Patent Publication No. 42261/1978 disclose processes for producing a plastic optical fiber comprising spinning the fiber by means of a screw extruder. In these processes, a polymer which has been continuously bulk polymerized is extruded by means of a twin-screw extr~der to form pellets or fibers while removing the unreacted monomer and volatile materials contained in the polymer. The optical fiber obtained by the processes is, however, contaminated with impurities such as metals resulting from the abrasion of the screw metal.
Thus, the o~tained optical fiber has a absorptivity coeffi-cient of 1.4 to 4 x 10 3 cm l, namely attenuation as high as about 600 to 1,700 dB/Km.
For the production of a plastic optical fiber having low attenuation, it is proposed to polymerize a monomer in the form of a preform and then to spin it by means of an extruder.
, 'lZZ2~S~
-- 2 ~
~ lowever, the preform made by the polymerization of the monomer is contaminated with dust or other Eoreign particles since it is once removed from a polymerization reactor into air before it is spun. It is extremely diffi-cult to prevent such contamination of the preform. For Example, U.S. Patent No. 4,161,500 discloses a process comprising forming a rod or a preform of polymethyl metha-cxylate (hereinafter referred to as "PMMA") in a gold-plated cylinder and then spinning it by means of a ram extruder and simultaneously extruding a cladding material by means of another extruder to form a cladding on the periphery of the PM~ fiber core to obtain an optical fiber. In this pro-cess, the preform should be, however, removed into air from the reactor, and the produced optical fiber has attenuation of liqht transmission not lower than 300 dB/Km. A process disclosed in U.S. Patent No. 4,138,194 provides an optical fiber made of deuterized polymethyl methacrylate (herein-after referred to as "P~MMA-d8)") having attenuation not lower than 225 dB/Km.
As a process in which the preform is not exposed to air, there is known, for example, a process disclosed in Japanese Patent Publication (unexamined) No. 84403/1982. In the process, polymerization of monomers is completed in a reactor, and the prepared pGlymer is spun from one end of the reactor by applying internal pressure with gas without using any extruder. Although the optical~fiber obtained by the process has low attenuation of 55 to 125 dBlKm for P~A
and of 20 dB/Km for P(~A-d8), the mechanical properties of the optical fiber is not satisfactory since the polymer is spun directly rom the cylinder by the application of the internal pressure to the cylinder and therefore the vis cosity of the polymer cannot be made so high, and further it is spun without stretching.
The present invention has been developed in order to overcome the drawbacks of the above described conven-tional processes and to provide a process and an apparatus for the production of a plastic optical fiber having low attenuation of light transmission and good mechanical properties.
SUMMARY OF THE INVENTION
According to the first aspect of the invention, there is provided a process for producing a plastic optical fiber which comprises riltering a monomer composition comprising a purified monomer, a polymerization initiator and a chain transfer agent through a filter made o~ a porous material; polymerizing the filtered monomer composition s~lbstantially free from optically foreign substances in an aimosphere of inert gas in a cylinde.r with stirring; conti-nuing the polymerization without stirring after viscosity of the polymeri~ation mixture reaches to a certain value to complete the polymeri~ation; heating the polymer at a temperature not lower than its softening poir.t with removing volatile components; transferring the polymer in a spinning head connected with one end of the cylinder to form a fiber ~z~s~
core and simultaneously forming a cladding on the periphery of the core; and drawing the opt:ical fiber.
According to the second aspect of the invention, there is provided an apparatus for producing a plastic optical fiber which comprises a cylinder; a monomer charging inlet connected with the cylinder; a filter made of a porous material connected with the monomer charying inlet; a spinning head connected with one end of the cylinder by which a core of the optical fiber is formed;.a stirrer which stirs a monomer composition in the cylinder and can be removed from the cylinder; means for transferring a polymer produced in the cylinder to the spinning head; means for forming.a cladding on the periphery of the core which is connected with the spinning head; and means for drawing the produced optical fiber.
BRIEF DESCXIPTION OF THE DRAWINGS
Fig. 1 shows a schematic view of an apparatus according to the invention in the step of polymerization of the monomer composition, and Fig. 2 shows a schematic par~ial view of the apparatus of Fig. 1 in the steps of forming the core and cladding of the optical fiber and drawing it.
DETAILED DESCRIPTION OF THE DRAWINGS
Reference is made to Figs. 1 and 2 which illus-trate one embodiment of the apparatus according to the invention for producing the plastic optical fiber.
~L~2~5i~
~ 5 --The monomer composition comprising the monomer, the polymerization initiator ancl the chain transer agent is prepared in a monomer purifying vessel 1, in which the monomer composition is purified by distillation under S reduced pressure or by mixing the components which have been purified separately. The pllrified monomer composition is transferred to a monomer tank 2. Then, a predetermined amount of the monomer composition is charged in a cylinder 4 through a monomer charging inlet 3, during which the monomer composition is filtered through a filter 13 made of a porous material and positioned between the monomer tank 2 and the inlet 3 in order to make it substantially free from opti-cally foreign substances. Before the charge of the monomer composition, the c~linder is evacuated, and after the - 15 monomer composition is transferred to a reaction chamber 5 of the cylinder 4, the cylinder is flashed with inert gas such as nitrogen gas. In Figs. 1 and 2, numeral 6 desig-nates the monomer composition in the reaction chamber 5, in which a stirrer 7 is immersed. One end of the cylinder 4 is sealed with a ram 8, and the other end is connected with a cpinning head 9 and sealed with a valve (not shown) provided therein.
_ The purified monomer composition 6 is polymerized in an atmosphere of inert gas under pressure of from atmos-pheric pressure to 10 Kg/cm2, during which the composition is heated to a temperature of 80 to 150C by an outer heater 10 provided around the reaction chamber 5 of the cylinder 4.
~ ~2~215S~
When the polymerization proceeds to a certain degree and the reaction mixture becomes viscous, the stirrer 7 is removed from the reaction chamber 5 and the polymeri-zation is continued to complete the polymerization. The stirrer 7 may be removed at a viscosity at which the reac~
tion mixture is not throughly stirrred by the stirrer. If necessary, the stirrer 7 may be removed before the reaction mixture becomes as viscous as described above. Further, the time of the removal of the stirrer is not uniformly deter-iO mined based on the viscosity of the reaction mixture sincethe effect of stirring depends on the type of the stirrer, the volume of the cylinder and the polymerization tempera-ture.
After the completion of the polymer.ization, the unreacted monomer and other volatile materials are reved by diminishing the interior pressure of the cylinder 4, and simultaneously the thus obtained polymer is heated to a temperature not lower than its softening point, for example, 230 to 250C.
Thereafter, by forwarding the hydraulic ram 8 toward the reaction chamber 5, the melted polymer is trans-ferred to the spinning head 9 under constant pressure to form a fiber core. As means for transferring the polymer to the spinning head, not only the ram 8 but also pressurized gas may be used. With the spinning head 9, cladding means 11 such as a screw or a ram extruder is connected. As soon as the core of the optical fiber is formed by the spïnning Z~35~
head, a cladding material is cladded on the peripher~ of the core. Preferably, a gear pump 12 provided at the tip of the extruder 11 stabilizes the delivery rate. The cladding means may be means for coating the cladding material on the periphery of the core.
After extruded from the spinning head 9, the plastic optical fiber comprising the core and the cladding cladded on the periphery of the core is drawn by drawing means (not shown~. The draw rate depends on-the extrusion rates of the ram 8 and the extruder ll and is usually 1 to 40 m/min., preferably, 1 to 5 m/min When it is less than 1 m/min., the production efficiency of the optical fiber is decreased, and when it is higher than 40 m/min., irregulari-ties such as surge appear on an interface between the core and the cladding. Particularly, when the draw rate is less than 5 m/min., such irregularities hardly appearsu Specific examples of the monomer to be used as the core according to the invention are those can afford transparent amorphous polymers such as methacrylates 5eg.
methyl methacrylate, phenyl methacrylate, isobornyl metha-crylate, etc.), styrene and its derivatives (eg. p-tert-butylstyrene, etc.). These monomers include ones in that all or a part of hydrogen atoms are substituted with deute-rium atoms~
Specific examples o~ the polymerization initiator are azoalkanes teg. azomethane, azopropane, azo-t-butane, azobisisobutyronitrile, etc.) and peroxides (eg.
~Z~S4 di-t-butylperoxide, t-butyl peracetate, etc.). Speciic examples of the chain transfer agent are mercaptans such as methylmercaptan, ethylmercaptan, propylmercaptan, butylmercaptan, etc.
The cladding material to be used according to the invention should have a refractive index lower than that of the polymer of the core. Its examples are a homopolymer of fluorine-containing methacrylate, copolymers of fluorine-containing methacrylate with, for example, methyl methacry-late, silicone resins, polyvinylidene fluoride, vinylidene fluoride/vinyl acetate copolymer, etc.
The porous material from which the filter is made should be inactive to the monomer composition for the core and not be swelled by the composition. Specific examples of the porous material are those made of polyolefins such as polypropylene, fluororesins such as polytetrafluoroethylene and copolymers of tetrafluoroethylene, ceramics, etc. The pore size of the porous material is selected so as to remove any size of the optically foreign substances that disturb the transmission of the light in the core. Generally, the average pore size is no larger than 1,000 A, preferably not larger than 800 A. Generally, the average pore size is not less than 50 A, preferably not less than 100 A, more prefe-rably not less than 150 A. When the pore size is too small, the filtration rate of the monomer composition is too low, which makes the whole process long.
~2Z~S~
_ 9 _ The present invention will be hereinafter explained further in detail by following Example, Example An apparatus described in Figs. 1 and 2 was used.
A purified monomer composition 1800 ml) of methyl methacrylate (hereinafter referred to as "MMA") containing as a polymerization initiator, di-tert-butylperoxide (0.01 %
by mole) and as a chain transfer agent, t-butylmercaptan ~0.3 % by mole) was filtered through a filte~ made of a polypropylene having an average pore size of 20~ A and then charged in the reaction chamber of the super patented SUS
304 made cylinder. Then, nitrogen gas was flashed in the interior of the cylinder to keep the interior pressure to 5 to 8 Kg/cm2, and the monomer composition was polymerized at 15 a temperature of fxom 120 to 130C for about three hours with stirring till the composition became viscous.
After removing the stirrer from the reaction chamber to stop stirring, the polymerization was continued.
After polymerizing for eight hours, the pressure of the cylinder was reduced to remove volatile materials including the unreacted MMA from PMMA for 4 hours, while the tempera-ture was elavated to 240C to melt PMMA. After replacing the atmosphere with nitrogen gas, melt PMMA was transferred to the spinning head by forwarding the ram in the cylinder.
PM~ was formed in a fiber core having a diameter of O . 30 mm by the spinning head. A copolymer of octafluoropentyl methacrylate and MMA in the weight ratio of 1:1 (n=1.45) as ~Z8S~
the cladding material was extruded from the screw extruder connected with the spinning head on the periphery of the just Pormed fiber core to form the cladding having a thick-ness of 0.05 mm. The optical fiber comprising the core S extruded from the spinning head and the cladding surrou~ding the core was drawn at a rate of 4 m/min.
The properties of the thus produced optical ~iber were examined. Attenuation of light transmission of the optical fiber was 80 d~/Km for a wave length of 570 nm, and its tensile strength was 10 Kg/mm2, both of which were satisfactory.
Since, according to the invention, the fiber core is formed without using any screw extruder, it is not contaminated with metal particles due to the abrasion of the screw and the cylinderO Since the polymer is polymerized and spun in a closed system and thereby it is not exposed to air in the form of a preform, it is not contaminated with dust or other foreign particles, and its attenuation is lower than lO0 ds/Km.
In addition, since the polymer is extruded from the cylinder to the spinning head by the hydraulic ram, the polymer having large degree of polymerization can be ext-_ ruded, and therefore, the optical fiber having excellent mechanical properties is produced.
PLASTIC OPTICAL FIBER
FIELD OE` THE INVENTION
The present invention relates to a process and an apparatus for the production of a plastic optical fiber having low attenuation of light transmission and good mechanical properties.
B~CKGROUND OF ~E INVENTION
U.S. Patent No. 3,993,834 and Japanese Patent Publication No. 42261/1978 disclose processes for producing a plastic optical fiber comprising spinning the fiber by means of a screw extruder. In these processes, a polymer which has been continuously bulk polymerized is extruded by means of a twin-screw extr~der to form pellets or fibers while removing the unreacted monomer and volatile materials contained in the polymer. The optical fiber obtained by the processes is, however, contaminated with impurities such as metals resulting from the abrasion of the screw metal.
Thus, the o~tained optical fiber has a absorptivity coeffi-cient of 1.4 to 4 x 10 3 cm l, namely attenuation as high as about 600 to 1,700 dB/Km.
For the production of a plastic optical fiber having low attenuation, it is proposed to polymerize a monomer in the form of a preform and then to spin it by means of an extruder.
, 'lZZ2~S~
-- 2 ~
~ lowever, the preform made by the polymerization of the monomer is contaminated with dust or other Eoreign particles since it is once removed from a polymerization reactor into air before it is spun. It is extremely diffi-cult to prevent such contamination of the preform. For Example, U.S. Patent No. 4,161,500 discloses a process comprising forming a rod or a preform of polymethyl metha-cxylate (hereinafter referred to as "PMMA") in a gold-plated cylinder and then spinning it by means of a ram extruder and simultaneously extruding a cladding material by means of another extruder to form a cladding on the periphery of the PM~ fiber core to obtain an optical fiber. In this pro-cess, the preform should be, however, removed into air from the reactor, and the produced optical fiber has attenuation of liqht transmission not lower than 300 dB/Km. A process disclosed in U.S. Patent No. 4,138,194 provides an optical fiber made of deuterized polymethyl methacrylate (herein-after referred to as "P~MMA-d8)") having attenuation not lower than 225 dB/Km.
As a process in which the preform is not exposed to air, there is known, for example, a process disclosed in Japanese Patent Publication (unexamined) No. 84403/1982. In the process, polymerization of monomers is completed in a reactor, and the prepared pGlymer is spun from one end of the reactor by applying internal pressure with gas without using any extruder. Although the optical~fiber obtained by the process has low attenuation of 55 to 125 dBlKm for P~A
and of 20 dB/Km for P(~A-d8), the mechanical properties of the optical fiber is not satisfactory since the polymer is spun directly rom the cylinder by the application of the internal pressure to the cylinder and therefore the vis cosity of the polymer cannot be made so high, and further it is spun without stretching.
The present invention has been developed in order to overcome the drawbacks of the above described conven-tional processes and to provide a process and an apparatus for the production of a plastic optical fiber having low attenuation of light transmission and good mechanical properties.
SUMMARY OF THE INVENTION
According to the first aspect of the invention, there is provided a process for producing a plastic optical fiber which comprises riltering a monomer composition comprising a purified monomer, a polymerization initiator and a chain transfer agent through a filter made o~ a porous material; polymerizing the filtered monomer composition s~lbstantially free from optically foreign substances in an aimosphere of inert gas in a cylinde.r with stirring; conti-nuing the polymerization without stirring after viscosity of the polymeri~ation mixture reaches to a certain value to complete the polymeri~ation; heating the polymer at a temperature not lower than its softening poir.t with removing volatile components; transferring the polymer in a spinning head connected with one end of the cylinder to form a fiber ~z~s~
core and simultaneously forming a cladding on the periphery of the core; and drawing the opt:ical fiber.
According to the second aspect of the invention, there is provided an apparatus for producing a plastic optical fiber which comprises a cylinder; a monomer charging inlet connected with the cylinder; a filter made of a porous material connected with the monomer charying inlet; a spinning head connected with one end of the cylinder by which a core of the optical fiber is formed;.a stirrer which stirs a monomer composition in the cylinder and can be removed from the cylinder; means for transferring a polymer produced in the cylinder to the spinning head; means for forming.a cladding on the periphery of the core which is connected with the spinning head; and means for drawing the produced optical fiber.
BRIEF DESCXIPTION OF THE DRAWINGS
Fig. 1 shows a schematic view of an apparatus according to the invention in the step of polymerization of the monomer composition, and Fig. 2 shows a schematic par~ial view of the apparatus of Fig. 1 in the steps of forming the core and cladding of the optical fiber and drawing it.
DETAILED DESCRIPTION OF THE DRAWINGS
Reference is made to Figs. 1 and 2 which illus-trate one embodiment of the apparatus according to the invention for producing the plastic optical fiber.
~L~2~5i~
~ 5 --The monomer composition comprising the monomer, the polymerization initiator ancl the chain transer agent is prepared in a monomer purifying vessel 1, in which the monomer composition is purified by distillation under S reduced pressure or by mixing the components which have been purified separately. The pllrified monomer composition is transferred to a monomer tank 2. Then, a predetermined amount of the monomer composition is charged in a cylinder 4 through a monomer charging inlet 3, during which the monomer composition is filtered through a filter 13 made of a porous material and positioned between the monomer tank 2 and the inlet 3 in order to make it substantially free from opti-cally foreign substances. Before the charge of the monomer composition, the c~linder is evacuated, and after the - 15 monomer composition is transferred to a reaction chamber 5 of the cylinder 4, the cylinder is flashed with inert gas such as nitrogen gas. In Figs. 1 and 2, numeral 6 desig-nates the monomer composition in the reaction chamber 5, in which a stirrer 7 is immersed. One end of the cylinder 4 is sealed with a ram 8, and the other end is connected with a cpinning head 9 and sealed with a valve (not shown) provided therein.
_ The purified monomer composition 6 is polymerized in an atmosphere of inert gas under pressure of from atmos-pheric pressure to 10 Kg/cm2, during which the composition is heated to a temperature of 80 to 150C by an outer heater 10 provided around the reaction chamber 5 of the cylinder 4.
~ ~2~215S~
When the polymerization proceeds to a certain degree and the reaction mixture becomes viscous, the stirrer 7 is removed from the reaction chamber 5 and the polymeri-zation is continued to complete the polymerization. The stirrer 7 may be removed at a viscosity at which the reac~
tion mixture is not throughly stirrred by the stirrer. If necessary, the stirrer 7 may be removed before the reaction mixture becomes as viscous as described above. Further, the time of the removal of the stirrer is not uniformly deter-iO mined based on the viscosity of the reaction mixture sincethe effect of stirring depends on the type of the stirrer, the volume of the cylinder and the polymerization tempera-ture.
After the completion of the polymer.ization, the unreacted monomer and other volatile materials are reved by diminishing the interior pressure of the cylinder 4, and simultaneously the thus obtained polymer is heated to a temperature not lower than its softening point, for example, 230 to 250C.
Thereafter, by forwarding the hydraulic ram 8 toward the reaction chamber 5, the melted polymer is trans-ferred to the spinning head 9 under constant pressure to form a fiber core. As means for transferring the polymer to the spinning head, not only the ram 8 but also pressurized gas may be used. With the spinning head 9, cladding means 11 such as a screw or a ram extruder is connected. As soon as the core of the optical fiber is formed by the spïnning Z~35~
head, a cladding material is cladded on the peripher~ of the core. Preferably, a gear pump 12 provided at the tip of the extruder 11 stabilizes the delivery rate. The cladding means may be means for coating the cladding material on the periphery of the core.
After extruded from the spinning head 9, the plastic optical fiber comprising the core and the cladding cladded on the periphery of the core is drawn by drawing means (not shown~. The draw rate depends on-the extrusion rates of the ram 8 and the extruder ll and is usually 1 to 40 m/min., preferably, 1 to 5 m/min When it is less than 1 m/min., the production efficiency of the optical fiber is decreased, and when it is higher than 40 m/min., irregulari-ties such as surge appear on an interface between the core and the cladding. Particularly, when the draw rate is less than 5 m/min., such irregularities hardly appearsu Specific examples of the monomer to be used as the core according to the invention are those can afford transparent amorphous polymers such as methacrylates 5eg.
methyl methacrylate, phenyl methacrylate, isobornyl metha-crylate, etc.), styrene and its derivatives (eg. p-tert-butylstyrene, etc.). These monomers include ones in that all or a part of hydrogen atoms are substituted with deute-rium atoms~
Specific examples o~ the polymerization initiator are azoalkanes teg. azomethane, azopropane, azo-t-butane, azobisisobutyronitrile, etc.) and peroxides (eg.
~Z~S4 di-t-butylperoxide, t-butyl peracetate, etc.). Speciic examples of the chain transfer agent are mercaptans such as methylmercaptan, ethylmercaptan, propylmercaptan, butylmercaptan, etc.
The cladding material to be used according to the invention should have a refractive index lower than that of the polymer of the core. Its examples are a homopolymer of fluorine-containing methacrylate, copolymers of fluorine-containing methacrylate with, for example, methyl methacry-late, silicone resins, polyvinylidene fluoride, vinylidene fluoride/vinyl acetate copolymer, etc.
The porous material from which the filter is made should be inactive to the monomer composition for the core and not be swelled by the composition. Specific examples of the porous material are those made of polyolefins such as polypropylene, fluororesins such as polytetrafluoroethylene and copolymers of tetrafluoroethylene, ceramics, etc. The pore size of the porous material is selected so as to remove any size of the optically foreign substances that disturb the transmission of the light in the core. Generally, the average pore size is no larger than 1,000 A, preferably not larger than 800 A. Generally, the average pore size is not less than 50 A, preferably not less than 100 A, more prefe-rably not less than 150 A. When the pore size is too small, the filtration rate of the monomer composition is too low, which makes the whole process long.
~2Z~S~
_ 9 _ The present invention will be hereinafter explained further in detail by following Example, Example An apparatus described in Figs. 1 and 2 was used.
A purified monomer composition 1800 ml) of methyl methacrylate (hereinafter referred to as "MMA") containing as a polymerization initiator, di-tert-butylperoxide (0.01 %
by mole) and as a chain transfer agent, t-butylmercaptan ~0.3 % by mole) was filtered through a filte~ made of a polypropylene having an average pore size of 20~ A and then charged in the reaction chamber of the super patented SUS
304 made cylinder. Then, nitrogen gas was flashed in the interior of the cylinder to keep the interior pressure to 5 to 8 Kg/cm2, and the monomer composition was polymerized at 15 a temperature of fxom 120 to 130C for about three hours with stirring till the composition became viscous.
After removing the stirrer from the reaction chamber to stop stirring, the polymerization was continued.
After polymerizing for eight hours, the pressure of the cylinder was reduced to remove volatile materials including the unreacted MMA from PMMA for 4 hours, while the tempera-ture was elavated to 240C to melt PMMA. After replacing the atmosphere with nitrogen gas, melt PMMA was transferred to the spinning head by forwarding the ram in the cylinder.
PM~ was formed in a fiber core having a diameter of O . 30 mm by the spinning head. A copolymer of octafluoropentyl methacrylate and MMA in the weight ratio of 1:1 (n=1.45) as ~Z8S~
the cladding material was extruded from the screw extruder connected with the spinning head on the periphery of the just Pormed fiber core to form the cladding having a thick-ness of 0.05 mm. The optical fiber comprising the core S extruded from the spinning head and the cladding surrou~ding the core was drawn at a rate of 4 m/min.
The properties of the thus produced optical ~iber were examined. Attenuation of light transmission of the optical fiber was 80 d~/Km for a wave length of 570 nm, and its tensile strength was 10 Kg/mm2, both of which were satisfactory.
Since, according to the invention, the fiber core is formed without using any screw extruder, it is not contaminated with metal particles due to the abrasion of the screw and the cylinderO Since the polymer is polymerized and spun in a closed system and thereby it is not exposed to air in the form of a preform, it is not contaminated with dust or other foreign particles, and its attenuation is lower than lO0 ds/Km.
In addition, since the polymer is extruded from the cylinder to the spinning head by the hydraulic ram, the polymer having large degree of polymerization can be ext-_ ruded, and therefore, the optical fiber having excellent mechanical properties is produced.
Claims (11)
1. A process for producing a plastic optical fiber which comprises filtering a monomer composition comprising a purified monomer, a polymerization initiator and a chain transfer agent through a filter made of a porous material;
polymerizing the filtered monomer composition substantially free from optically foreign substances in an atmosphere of inert gas in a cylinder with stirring; discontinuing the stirring when the polymerization mixture becomes viscous and completing the polymerization without stirring; heating the polymer at a temperature not lower than its softening point while removing volatile components; transferring the polymer to a spinning head connected to one end of the cylinder to form a fiber core and simultaneously forming a cladding on the periphery of the core; and drawing the optical fiber.
polymerizing the filtered monomer composition substantially free from optically foreign substances in an atmosphere of inert gas in a cylinder with stirring; discontinuing the stirring when the polymerization mixture becomes viscous and completing the polymerization without stirring; heating the polymer at a temperature not lower than its softening point while removing volatile components; transferring the polymer to a spinning head connected to one end of the cylinder to form a fiber core and simultaneously forming a cladding on the periphery of the core; and drawing the optical fiber.
2. A process according to claim 1, wherein the polymerization pressure is from atmospheric pressure to 10 Kg/cm2.
3. A process according to claim 1, wherein the polymerization temperature is from 80 to 150°C.
4. A process according to claim 1, wherein the monomer is selected from the group consisting of methacrylates and styrene and its derivatives.
5. An apparatus for producing a plastic optical fiber which comprises a cylinder; a monomer inlet connected to the cylinder; a filter made of a porous material connected to the monomer inlet; a spinning head connected to one end of the cylinder by which a core of the optical fiber is formed; a stirrer which stirs the monomer composition in the cylinder and can be removed from the cylinder; means for transferring a polymer produced in the cylinder to the spinning head;
means for forming a cladding on the periphery of the optical fiber core; and means for drawing the produced optical fiber.
means for forming a cladding on the periphery of the optical fiber core; and means for drawing the produced optical fiber.
6. An apparatus according to claim 5, wherein the means for transferring the polymer to the spinning head is a ram inserted in the other end of the cylinder.
7. An apparatus according to claim 5, wherein the means for forming the cladding is an extruder.
8. An apparatus according to claim 7, wherein the extruder is provided with a gear pump.
9. An apparatus according to claim 5, wherein the porous material is made from one selected from the group consisting of polypropylene, polytetrafluoroethylene and ceramics.
10. An apparatus according to claim 9, wherein the porous material has an average pore size of not more than 1,000 .ANG..
11. An apparatus according to claim 9, wherein the porous material has an average pore size of not less than 50 .ANG..
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP51144/1983 | 1983-03-25 | ||
| JP11441983A JPS5910213A (en) | 1983-06-27 | 1983-06-27 | Engagement device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1222854A true CA1222854A (en) | 1987-06-16 |
Family
ID=14637232
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000450103A Expired CA1222854A (en) | 1983-03-25 | 1984-03-21 | Process and apparatus for production of plastic optical fiber |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5910213A (en) |
| CA (1) | CA1222854A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0267178U (en) * | 1988-11-11 | 1990-05-21 |
-
1983
- 1983-06-27 JP JP11441983A patent/JPS5910213A/en active Granted
-
1984
- 1984-03-21 CA CA000450103A patent/CA1222854A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6132803B2 (en) | 1986-07-29 |
| JPS5910213A (en) | 1984-01-19 |
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