EP1451005A2 - Method for making a plastic optical fiber, and resulting plastic optical fiber - Google Patents
Method for making a plastic optical fiber, and resulting plastic optical fiberInfo
- Publication number
- EP1451005A2 EP1451005A2 EP02803435A EP02803435A EP1451005A2 EP 1451005 A2 EP1451005 A2 EP 1451005A2 EP 02803435 A EP02803435 A EP 02803435A EP 02803435 A EP02803435 A EP 02803435A EP 1451005 A2 EP1451005 A2 EP 1451005A2
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- EP
- European Patent Office
- Prior art keywords
- polymer
- compositions
- optical fiber
- index
- plastic optical
- 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.)
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Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
- G02B1/045—Light guides
- G02B1/046—Light guides characterised by the core material
Definitions
- the present invention relates to a process for manufacturing a plastic optical fiber, as well as a plastic optical fiber obtained by this process. It relates in particular to plastic optical fibers with index jump and those with index gradient.
- Plastic index-jump optical fibers which can be used in a spectral range covering the visible to the near infrared, are advantageous because their installation is simpler than that of silica fibers because of their larger diameter.
- Gradient index plastic optical fibers which can be used in the same spectral range, are interesting because they can be applied to broadband access networks.
- a graded index plastic optical fiber comprises at least one basic polymer and another compound, called dopant, comprising one or more monomers or polymers. The proportion of the base polymer is substantially the same over the entire fiber and the proportion of the dopant varies from the core to the periphery of the fiber so as to form the desired gradient or index jump.
- the manufacture of such plastic optical fibers is delicate, since it is necessary to distribute the dopant varying from the core to the periphery of a plastic optical fiber.
- the fiber must have a refractive index profile of the gradient index type as regular as possible, the variation of refractive index between the center and the periphery of the fiber is generally between 0.01 and 0.03.
- document EP-1 067 222 discloses a method for manufacturing a plastic optical fiber with index gradient, the index of which varies continuously between the center and the periphery of the fiber.
- the fiber is made from at least one polymer P and at least one reactive diluent D1 serving as a dopant making it possible to vary its refractive index.
- This process comprises the following stages: • preparation of two compositions of different refractive index, the difference in refractive index between the two compositions being at least 5.10 ⁇ 3 , each comprising at least the polymer P, one of the compositions, known as the first composition, further comprising at least the reactive diluent D1, a radical polymerization initiator being present in at least one of the compositions,
- the polymer P and the reactive diluent D1 are also chosen such that:
- the polymer P has a molar mass of between 1,000 and 20,000 g. moles "1 and the reactive diluent D1 has a molar mass of between 100 and 1000 g. moles " 1 ,
- the reactive diluent D1 comprises at least one unsaturated group reactive with respect to UV, such as vinyl groups and acrylic groups.
- the molar masses mentioned above are number average molar masses. This is also the case for the molar masses mentioned in all that follows.
- a preferred base polymer is of the poly (fluoro) methacrylate type, and more generally of the PMMA (polymethylmethacrylate) type.
- PMMA polymethylmethacrylate
- the aim of the present invention is therefore to develop a process for manufacturing an index gradient optical fiber making it possible to obtain plastic optical fibers capable of operating at wavelengths greater than 500 nm without causing prohibitive attenuation of the transmitted optical signal.
- the present invention provides for this purpose a method of manufacturing a plastic optical fiber from at least one polymer P, said method being characterized in that said polymer P is a copolymer comprising at least two repeating units P1 and P2 of following general formulas, i and j corresponding to a repetitive number of units:
- the methods according to the invention apply as well to the production of index gradient optical fibers as to that of index jump fibers.
- the copolymer P can be obtained from chlorotrifluoroethylene or tetrafluoroethylene, industrial fluorinated monomers, and from vinylene carbonate, a readily accessible non-halogenated monomer.
- the copolymer containing a lot of fluorine and therefore less hydrogen than the polymers of the prior art of PMMA type, which leads to increased transparency, and having a cyclic structure, which leads to an amorphous structure and therefore to properties optical transmission fibers, the fibers obtained by the method according to the invention are particularly suitable for applications at wavelengths greater than 500 nm, typically in the transmission windows located around 650, 850, 1300 and 1550 nm.
- the present invention provides a method of manufacturing a plastic optical fiber with index jump, the index of which varies discontinuously between the center and the periphery of the fiber, or with an index gradient, the index of which varies continuously between the center and the periphery of the fiber, from at least said polymer P and from at least one reactive diluent D1 making it possible to vary the refractive index of said fiber, said method comprising the following steps:
- compositions with different refractive index preparation of two compositions with different refractive index, the difference in refractive index between the two compositions being at least 5.10 "3 , each comprising at least polymer P, one of the compositions, known as the first composition, comprising in addition at least the reactive diluent D1, a radical polymerization initiator being present in at least one of the compositions, spinning • crosslinking of the reactive diluent leading to a plastic optical fiber.
- said method further comprises, after the step of preparing said compositions, a step of active mixing of the two compositions in order to obtain the continuous variation of the refractive index optical fiber, followed by spinning of said mixture.
- the crosslinking is a photo-crosslinking and the initiator is a photoinitiator.
- the molar mass of the polymer P is between 1000 and 20000 g. moles "1 and the reactive diluent D1 has a molar mass of between 100 and 1000 g. moles " 1 . These choices limit the viscosity of the composition and facilitate spinning.
- the reactive diluent D1 comprises at least one unsaturated group reactive with respect to UV rays chosen from the group formed by vinyl groups and acrylic groups.
- An active mixture according to the process of the invention is a mixture which is helped to form, that is to say which is not produced only by diffusion; this active mixture can be obtained statically by forcing by a static diffusion means the mixture of the two compositions, most often by forced flow, or by dynamic means which actively produces such a mixture.
- Such a method has the advantage of being rapid, in particular much faster than if only the diffusion between the compositions is used, and of making it possible to obtain a concentration gradient and therefore a continuous refractive index and practically regular.
- the crosslinking kinetics are generally such that, under maximum exposure and complete transformation of the photoinitiator, the gel time is less than 10 s, preferably less than 2 s.
- the spinning of the index gradient mixture is followed by a photochemical or thermal crosslinking of the diluent reagent leading to the production of a cross-linked three-dimensional network. This process advantageously makes it possible to at least partially freeze the components of the plastic optical fiber.
- the plastic optical fiber thus obtained and its index gradient therefore have stability over time and stability in temperature.
- At least one of the two compositions comprises a monomer; in addition, at least one of the two compositions comprises at least one radical polymerization initiator, and preferably each of the two compositions comprises at least one radical polymerization initiator.
- the radical polymerization initiator is a compound which makes it possible to generate initiator radicals by thermal or photochemical decomposition of the crosslinking reaction.
- the second composition comprises at least one reactive diluent D2 also making it possible to vary the refractive index, the reactive diluent D2 being of refractive index substantially different from the refractive index of D1, having a molar mass of between 100 and 1000 g. moles "1 , and comprising at least one UV-reactive unsaturated group chosen from the group formed by vinyl groups and acrylic groups.
- the reactive diluents D1 and D2 have respective viscosities which are practically identical and the proportion by mass of the polymer P relative to the constituents of the composition is practically constant for each of the compositions, thus the process is easier to implement since the variation in the proportion of diluent (s) reactive (s) D1 and / or D2, mainly used to modulate the refractive index, does not significantly influence the viscosity of the compositions.
- the mixing of the two compositions is carried out at a temperature such that the viscosity at 20 ° C. of each of the two compositions is included between 1 and 25 Pa.s, preferably between 1 and 15 Pa.s.
- the spinning is carried out at a temperature such that the viscosity of each of the two compositions is greater than 500 mPa.s, preferably greater than 1000 mPa.s.
- the reactive groups carried by the constituents D1 and D2 are chosen from the group formed by vinyl groups and acrylic groups, that is to say chosen in particular from acrylates, methacrylates, vinyl ethers or propenyl ethers, these groups can be at least partially halogenated, most often fluorinated and / or chlorinated.
- any component of one of the compositions is an at least partially halogenated material, most often fluorinated and / or chlorinated.
- one of the two reactive diluents D1 or D2 is at least partially fluorinated and the other of the two reactive diluents D2 or D1 is at least partially chlorinated or chloro-fluorinated, and therefore has a refractive index substantially higher than that of the at least partially fluorinated monomer.
- the present invention provides a method for manufacturing a plastic optical fiber with an index gradient, the index of which varies continuously between the center and the periphery of the fiber, from at least said polymer.
- P and at least one dopant D making it possible to vary the refractive index of said fiber, the refractive index of said dopant being greater than that of said polymer P, said method comprising the following steps: • melting of polymer P in a tube • rotation of said tube around its axis • cooling of said tube so as to form inside said tube a tubular body of polymer P
- the present invention provides a method of manufacturing a plastic index-hopping optical fiber, the index of which varies discontinuously between the center and the periphery of the fiber, from at least said polymer P, said polymer P being spun in the molten state and simultaneously coated with a photocrosslinkable resin with a refractive index lower than that of polymer P, which is then photopolymerized.
- the present invention provides a method of manufacturing a plastic optical fiber with index jump, the index of which varies discontinuously between the center and the periphery of the fiber, starting from at least said polymer P, by coextrusion of said polymer P with another polymer of refractive index lower than that of said polymer P.
- the method according to the invention can of course also be implemented for the manufacture of optical waveguides.
- the present invention also relates to a plastic optical fiber with an index gradient obtained by the method according to the invention, as well as an optical waveguide obtained by this method.
- FIG. 1 schematically shows a device for implementing the method according to the invention.
- FIG. 2 shows a schematic view of the index profile of an optical fiber obtained by means of the device of Figure 1
- FIG. 3 shows the attenuation spectra of a plastic optical fiber with an index gradient obtained from methods of the prior art and from a method according to one of the embodiments of the invention.
- the common elements have the same reference numbers.
- two compositions are prepared, each comprising a copolymer P.
- One of these compositions further comprises at least one reactive diluent D1, which is preferably a monomer.
- the other composition comprises at least one reactive diluent D2, which is also preferably a monomer.
- the concentration of D1 is different in each of the two compositions, which gives a different refractive index to each composition.
- the two values of refraction index thus obtained constitute the maximum and the minimum of the parabolic index gradient gradient curve that one seeks to obtain for the plastic optical fiber resulting from the process (see FIG. 2).
- the copolymer P used in the process of the invention comprises the repeating units P1 and P2 shown below.
- the unit P1 is derived from the polymerization of i monomers M1 and the unit P2 is derived from the polymerization of j monomers M2.
- the repeating entities P1 can come from a mixture of monomers of formula M1.
- the comonomer M2 giving rise to the repeating entities P2 is the vinylene carbonate of the following formula:
- any polymerization process known to a person skilled in the art using a solvent medium, in suspension in water or in emulsion for example, can be used. It is generally preferable to work in a solvent medium in order to control the exothermicity of the polymerization and to favor an intimate mixture of the different monomers.
- solvents commonly used there may be mentioned ethyl, methyl or butyl acetate, chlorofluorinated solvents such as F141b® (CFCl 2 -CH 3 ) or F113® (CF 2 Cl-CFCl 2 ).
- radical polymerization initiator it is possible to use free radical generators such as peroxide, hydroperoxide, percarbonate derivatives or even diazo compounds such as azobisisobutyronitrile (AlBN). It is also possible, in the case of processes carried out in an aqueous medium, to use inorganic free radical generators such as persulfates or so-called redox combinations.
- the polymerization temperature is dictated, in general, by the rate of decomposition of the selected initiator and is, in general, between 0 and 200 ° C, preferably between 40 and 120 ° C.
- the pressure is, in general, between atmospheric pressure and a pressure of 50 bars, more particularly between 2 bars and 20 bars.
- a pressure of 50 bars more particularly between 2 bars and 20 bars.
- the copolymer P used in the process according to the invention has a glass transition temperature (Tg) situated between 60 and 160 ° C, preferably between 80 and 140 ° C. This glass transition temperature is mainly linked to the content of units P2 present in the copolymer.
- the transparency of the polymer obtained also depends on the content of units P2.
- the content of motif P2, repeating unit resulting from the polymerization of monomers M2 can vary in the copolymer depending on the nature of X in P1.
- X F or Cl in P1
- the content of motif P2 in the copolymer is between substantially 30 and 70 mol%.
- the polymer P of the process according to the invention has a number-average molar mass (Mn) of between 500 and 10 6 g. moles "1 and preferably between 10 3 and 10 4 g. moles " 1 .
- Mn number-average molar mass
- VCA vinylene carbonate
- TBPP tertiobutyl perpivalate, at 75% by mass in isododecane
- F141b® 1, 1 , 1 -dichlorofluoroethane
- the Mn (number-average molar masses) are determined by CES analysis (steric exclusion chromatography). An apparatus from the company Spectra Physic "Winner Station” is used. Detection is carried out by refractive index.
- the column is a mixed C column
- PL gel of 5 microns from the company Polymer Laboratory and the solvent used is THF at a flow rate of 0.8 ml / min.
- Mn molar masses in number
- the Tg glass transition temperatures
- DSC differential scanning calorimetry
- a first temperature rise is carried out at 20 ° C./min followed by cooling and then a second rise in temperature during which the Tg or Tf (melting temperatures) are recorded
- the temperature range is from 50 ° C to 200 ° C if the Tg is greater than 60 ° C.
- the chlorine levels are determined in a conventional manner by mineralization in a PARR bomb with Na 2 O 2 followed by determination of the chlorides by argentimetry.
- the operation is carried out in a 160 ml stainless steel reactor, purged two to three times with 5 bars of nitrogen. 50 ml of an F141b® solution containing 0.6 ml (or 2.25 mmol) of TBPP initiator and 8.53 g are introduced by suction into the vacuum reactor (approximately 100 mbar of pressure).
- Example 2 The procedure is the same as in Example 1 with the same reagents and the same proportions using the ethyl acetate solvent in place of F141 b®. At the end of the reaction, a solution of polymer in ethyl acetate is obtained. The solvent is evaporated until a volume of about 20 ml is obtained and then the reaction product is precipitated with n-heptane. The precipitated polymer is filtered and then dried under vacuum at 60 ° C. 10 g of a colorless, transparent copolymer, soluble in THF or acetone, are obtained. The P1 / P2 molar ratio is 49/51 and the Tg is 106 ° C.
- Comparative examples 3, 5, 6 and 7 are carried out, as well as example 4, operating in the same manner as in example 2 with the amounts of CTFE and VCA reagents indicated in TABLE 1 below.
- examples and comparatives of TABLE 1 are brought into play at the start of the reaction x mmoles of CTFE and y mmoles of VCA, x and y having the following values according to the examples:
- Example 2 The procedure is the same as in Example 2 but with 7 g (or 81.3 mmol) of VCA and 11 g (or 110 mmol) of TFE in place of the CTFE. 14.6 g of copolymer are obtained. The copolymer is very soluble in acetone or THF. By evaporation of the acetone, a colorless, transparent film is obtained. 19 F NMR analysis indicates a P1 / P2 molar ratio of 70/30. The Tg of the copolymer is 82 ° C (DSC analysis).
- the two compositions C1 and C2 are prepared, making it possible to produce an optical fiber according to the invention by a UV type process.
- Two different compositions comprising a commercial photoinitiator, the reactive copolymer P of Example 1, 2 or 3 above, and a reactive diluent composed of two monomers in different proportions according to the composition, the two monomers being ( D1) and (D2)
- the photoinitiator may for example be an ⁇ -hydroxyketone (IRGACURE 184, DAROCUR 1173), a mono acyl phosphine (DAROCUR TPO) or a bis acyl phosphine (IRGACURE 819).
- D1 and D2 can be monomers having at least one acrylic, methacrylic, ⁇ -fluoroacrylic, ⁇ , ⁇ -difluoroacrylic or vinyl function comprising halogen groups (fluorinated and chlorinated).
- compositions C1 and C2 prepared from the mixture of copolymer P of Example 1, the reactive diluent D1 being trifluoroethyl acrylate (including the homopolymer at 20 ° C has a refractive index equal to 1.407), and the reactive diluent D2 being trifluoroethyl methacrylate (the homopolymer of which at 20 ° C. has a refractive index equal to 1.437).
- the photoinitiator is from the class of bis acyl phosphines (BAPO - IRGACURE 819). The quantities are calculated for 700 grams of composition.
- the ratio, in% by weight, of the copolymer P to the sum of the constituents of each composition is constant, while within the reactive diluent the relative proportion, in% by mass of D1 relative to the sum of D1 and D2 , varies from composition to composition.
- the continuous index variation is created by producing an active mixture of the two starting compositions C1 and C2.
- a mixing means which can be a static or dynamic type mixer.
- FIG. 1 represents a very schematic sectional view, in a plane comprising a central axis X, of a device for manufacturing an optical fiber according to the method of the invention.
- the device 10 comprises a static mixer 1.
- the compositions C1 and C2 of the table above are mixed there.
- the mixer 1 comprises two concentric cylinders 3 and 4 serving as reservoirs for the compositions C1 and C2. It is the cylindrical enclosure 8 of the mixer 1 which serves as a reservoir 4 for the composition C2.
- the composition C1 with the highest refractive index is placed in the central reservoir 3.
- the enclosure 8 comprises a sealed upper closure 8d which has two respective inlets 8g and 8f making it possible to ensure a controlled pressure in each of the respective tanks 3 and 4, for example by means of two positive displacement pumps (not shown).
- a controlled pressure can be applied to the two compositions C1 and C2 in order to obtain an identical flow if the two compositions C1 and C2 have the same viscosity.
- the enclosure 8 also includes a zone 8e where the two tanks 3 and 4 are concentric, isolated from each other, as well as a zone 8a whose upper limit is the bottom of the central tank 3 and whose lower limit East the bottom of the peripheral tank 4.
- Zone 8a corresponds to a zone for mixing the two compositions C1 and C2 by the mixer 1, namely a set 2 of plates (2a, 2b) superimposed and perforated with holes 12.
- the enclosure 8 further includes a conical area 8b where a homothetic variation of the section occurs, and finally a calibrated area 8c comprising a die 15, which gives the desired order of magnitude to the diameter of a plastic optical fiber with an index gradient 6 obtained .
- the fiiere 15 is an attached part, which makes it possible to easily change the calibration without having to change the mixer 1.
- the mixer 1 comprises in its zone 8a at least two, and here seven, perforated plates (2a, 2b) superposed one on the other above the others.
- This set 2 of plates (2a, 2b) is placed at the lower end of the central reservoir 3 so as to ensure a radial mixing of the compositions C1 and C2.
- a mixture 5 is obtained having a concentration gradient of compositions C1 and C2, in zone 8a.
- the mixture 5 is formed by the superposition of the plates (2a, 2b).
- Each plate 2a (respectively 2b) has holes 12, generally arranged in opposition with respect to each other from a plate 2a to an adjacent plate 2b (respectively from a plate 2b to an adjacent plate 2a).
- the mixture 5 thus obtained is brought to the calibrated die 15 from the zone 8c of the enclosure 8 by the conical zone 8b, the upper limit of which is the lower end of the last plate 2a.
- This homothetic variation makes it possible to preserve the form of the variation in concentration of the compositions C1 and C2.
- the wire obtained which is a plastic optical fiber with an index gradient, 6, is drawn by a capstan 10.
- the plastic optical fiber 6 is cured by photo- crosslinking using a source 7 of ultraviolet (UV) rays in a polymerized plastic optical fiber 9.
- UV ultraviolet
- the plastic optical fiber 9 is wound on a reel 11.
- the diameter of the fiber 9 is given by the die 15, but it can be refined according to the strength of the spinning carried out by means of the capstan 10.
- FIG. 2 shows a schematic view of the index profile obtained for an optical fiber manufactured by the device of Figure 1.
- the profile of the refractive index n of the optical fiber 6 of Figure 1 practically smoothed so as to form a gradient of parabolic shape, as a function of the distance r from the center of the fiber 6, which is on the axis X.
- the fiber thus obtained is therefore a gradient index fiber, but the above method can also make it possible to obtain a index-jump fiber.
- the active mixture of compositions C1 and C2 is not carried out.
- C1 and C2 are then introduced into a distributor pot extended by a die, where the final fiber dimameter and the proportion of core and cladding are governed by the pressure and the temperature of the compositions C1 and C2 as well as by the diameter of the sector.
- the present invention also relates to other types of methods for obtaining plastic optical fibers.
- the preform method 100 g of polymer P of the CTFE / VCA copolymer type, the molar proportion of CTFE motif varies between 30 and 70% of average molar mass of approximately 5.10 5 are melted at a temperature between 200 and 250 ° C in a cylindrical glass tube, without completely filling it so that a vacant space is made in the tube containing the polymer P before sealing it under vacuum. The tube in glass is then placed in a horizontal position in an oven.
- the tubular body thus obtained has an outside diameter of 17 mm and an inside diameter of 5 mm, and its refractive index is 1.45.
- a dopant D is then introduced into the central part of this tubular body, still in the glass tube. Its proportion is 4% by weight relative to the polymer P.
- the dopant it is preferable that it meets the following two conditions:
- ⁇ p- ⁇ p I is less than or equal to 7 (cal / cm 3 ) 1/2 .
- the assembly is again rotated in an oven.
- the dopant D thermally diffuses through the molten polymer P for 6 hours.
- the oven is finally gradually cooled at a speed of 15 ° C / hour to room temperature.
- a tubular body 17 mm in outside diameter and 4.5 mm in inside diameter is obtained with a gradient index of refraction profile.
- This tubular body constituting the preform of the plastic optical fiber with an index gradient, is placed in a drawing oven at a temperature between 200 and 250 ° C. Its upper part is connected to a vacuum pump during the spinning step. In this way, the preform shrinks and an optical fiber with a refractive index gradient is recovered. Its dimensions depend on the spinning speed, preferably between 5 and 10 m / min and on the oven temperature.
- polymers P according to the invention having a glass transition temperature higher than those of PMMA or of CYTOP, materials conventionally used in the known “preform” process, leads to fibers having a transparency greater than those obtained. with classic materials.
- FIG. 3 where is represented as a function of the wavelength in nm, the attenuation (in dB / km) of a plastic optical fiber with an index gradient obtained according to the process which has just been describes, from CYTOP polymer of the prior art (curve 31), PMMA polymer of the prior art (curve 32) and polymer (CTFE) 0.50 (VCA) 0.50 according to the invention (curve 33).
- plastic optical fibers with index jump it is possible for example to spin a polymer P according to the invention, for example obtained according to one of the examples above, in the state molten, and simultaneous deposition of a photocrosslinkable resin with a refractive index lower than that of the polymer P, this resin then being photopolymerized.
- the thickness of the resin layer thus deposited is for example of the order of 100 ⁇ m.
- a polymer of refractive index lower than that of the polymer P such as for example PVDF, Teflon ® AF by du Pont de Nemours or the Hyflon AD ® by AUSIMONT.
- compositions and examples given are for information only, and they can be modified without departing from the scope of the invention as long as the copolymer P retains the general characteristics mentioned above.
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Abstract
The invention concerns a method for making a plastic optical fiber from at least a polymer P, said method being characterized in that said polymer P is a copolymer comprising at least two repeating units P1 and P2 of general formulae (i) and (j), i and j corresponding to a repetitive number of units, said polymer P being transparent, of amorphous type and having a P2 unit content ranging substantially between 30 and 70 mole % for X=F of Cl in P1.
Description
PROCEDE DE FABRICATION D'UNE FIBRE OPTIQUE PLASTIQUE , ET FIBRE OPTIQUE PLASTIQUE OBTENUE PAR CE PROCEDEMETHOD FOR MANUFACTURING PLASTIC OPTICAL FIBER, AND PLASTIC OPTICAL FIBER OBTAINED BY THIS PROCESS
La présente invention concerne un procédé de fabrication d'une fibre optique plastique, ainsi qu'une fibre optique plastique obtenue par ce procédé. Elle concerne notamment les fibres optiques plastiques à saut d'indice et celles à gradient d'indice.The present invention relates to a process for manufacturing a plastic optical fiber, as well as a plastic optical fiber obtained by this process. It relates in particular to plastic optical fibers with index jump and those with index gradient.
Les fibres optiques plastiques à saut d'indice, utilisables dans une gamme spectrale couvrant le visible jusqu'au proche infrarouge, sont intéressantes car leur installation est plus simple que celle des fibres en silice du fait de leur diamètre plus important. Les fibres optiques plastiques à gradient d'indice, utilisables dans la même gamme spectrale, sont intéressantes car elles peuvent être appliquées aux réseaux d'accès large bande. Une fibre optique plastique à gradient d'indice comprend au moins un polymère de base et un autre composé, appelé dopant, comprenant un ou plusieurs monomères ou polymères. La proportion du polymère de base est sensiblement la même sur toute la fibre et la proportion du dopant varie du cœur à la périphérie de la fibre de façon à former le gradient ou le saut d'indice désirés.Plastic index-jump optical fibers, which can be used in a spectral range covering the visible to the near infrared, are advantageous because their installation is simpler than that of silica fibers because of their larger diameter. Gradient index plastic optical fibers, which can be used in the same spectral range, are interesting because they can be applied to broadband access networks. A graded index plastic optical fiber comprises at least one basic polymer and another compound, called dopant, comprising one or more monomers or polymers. The proportion of the base polymer is substantially the same over the entire fiber and the proportion of the dopant varies from the core to the periphery of the fiber so as to form the desired gradient or index jump.
La fabrication de telles fibres optiques plastiques, notamment de celles à gradient d'indice, est délicate, car il faut réaliser une distribution du dopant variant du cœur à la périphérie d'une fibre optique plastique. En effet, la fibre doit posséder un profil d'indice de réfraction de type gradient d'indice le plus régulier possible, dont la variation d'indice de réfraction entre le centre et la périphérie de la fibre est généralement comprise entre 0,01 et 0,03.The manufacture of such plastic optical fibers, in particular those with an index gradient, is delicate, since it is necessary to distribute the dopant varying from the core to the periphery of a plastic optical fiber. Indeed, the fiber must have a refractive index profile of the gradient index type as regular as possible, the variation of refractive index between the center and the periphery of the fiber is generally between 0.01 and 0.03.
Pour fabriquer ces fibres à gradient d'indice, on connaît par le document EP-1 067 222 un procédé de fabrication d'une fibre optique plastique à gradient d'indice dont l'indice varie continûment entre le centre et la périphérie de la fibre.
Selon ce procédé, la fibre est fabriquée à partir d'au moins un polymère P et d'au moins un diluant réactif D1 servant de dopant permettant de faire varier son indice de réfraction. Ce procédé comprend les étapes suivantes : • préparation de deux compositions d'indice de réfraction différent, la différence d'indice de réfraction entre les deux compositions étant au moins de 5.10"3, comprenant chacune au moins le polymère P, l'une des compositions, dite première composition, comprenant en outre au moins le diluant réactif D1 , un amorceur de polymérisation radicalaire étant présent dans au moins l'une des compositions,To manufacture these index gradient fibers, document EP-1 067 222 discloses a method for manufacturing a plastic optical fiber with index gradient, the index of which varies continuously between the center and the periphery of the fiber. . According to this process, the fiber is made from at least one polymer P and at least one reactive diluent D1 serving as a dopant making it possible to vary its refractive index. This process comprises the following stages: • preparation of two compositions of different refractive index, the difference in refractive index between the two compositions being at least 5.10 −3 , each comprising at least the polymer P, one of the compositions, known as the first composition, further comprising at least the reactive diluent D1, a radical polymerization initiator being present in at least one of the compositions,
• mélange actif des deux compositions afin d'obtenir la variation continue de l'indice de la fibre optique• active mixing of the two compositions in order to obtain the continuous variation of the index of the optical fiber
• filage du mélange• spinning of the mixture
• réticulation du mélange conduisant à une fibre optique plastique à gradient d'indice de réfraction.• crosslinking of the mixture leading to a plastic optical fiber with a refractive index gradient.
Selon ce procédé, on choisit en outre le polymère P et le diluant réactif D1 tels que :According to this process, the polymer P and the reactive diluent D1 are also chosen such that:
- le polymère P est de masse molaire comprise entre 1 000 et 20 000 g. moles"1 et le diluant réactif D1 est de masse molaire comprise entre 100 et 1 000 g. moles"1,- the polymer P has a molar mass of between 1,000 and 20,000 g. moles "1 and the reactive diluent D1 has a molar mass of between 100 and 1000 g. moles " 1 ,
- le diluant réactif D1 comprend au moins un groupement insaturé réactif vis-à-vis des UV tels que les groupements vinyliques et les groupements acryliques.the reactive diluent D1 comprises at least one unsaturated group reactive with respect to UV, such as vinyl groups and acrylic groups.
Les masses molaires mentionnées ci-dessus sont des masses molaires moyennes en nombre. C'est également le cas des masses molaires mentionnées dans tout ce qui suit.The molar masses mentioned above are number average molar masses. This is also the case for the molar masses mentioned in all that follows.
Selon le document mentionné précédemment, un polymère de base préféré est du type poly ( fluoro) méthacrylate, et plus généralement de type PMMA (polyméthylméthacrylate).
Or, du fait de l'absorption élevée des liaisons C-H de ce polymère, l'application des fibres obtenues à partir de ce dernier est limitée aux longueurs d'onde visibles, inférieures à 800 nm.According to the document mentioned above, a preferred base polymer is of the poly (fluoro) methacrylate type, and more generally of the PMMA (polymethylmethacrylate) type. However, due to the high absorption of CH bonds of this polymer, the application of the fibers obtained from the latter is limited to the visible wavelengths, less than 800 nm.
Le but de la présente invention est donc de mettre au point un procédé de fabrication d'une fibre optique à gradient d'indice permettant d'obtenir des fibres optiques plastiques capables de fonctionner aux longueurs d'ondes supérieures à 500 nm sans entraîner d'atténuation prohibitive du signal optique transmis.The aim of the present invention is therefore to develop a process for manufacturing an index gradient optical fiber making it possible to obtain plastic optical fibers capable of operating at wavelengths greater than 500 nm without causing prohibitive attenuation of the transmitted optical signal.
La présente invention propose à cet effet un procédé de fabrication d'une fibre optique plastique à partir d'au moins un polymère P, ledit procédé étant caractérisé en ce que ledit polymère P est un copolymère comprenant au moins deux unités répétitives P1 et P2 de formules générales suivantes, i et j correspondant à un nombre répétitif d'unités :The present invention provides for this purpose a method of manufacturing a plastic optical fiber from at least one polymer P, said method being characterized in that said polymer P is a copolymer comprising at least two repeating units P1 and P2 of following general formulas, i and j corresponding to a repetitive number of units:
ledit copolymère P étant transparent, de nature amorphe et ayant une teneur en motif P2 comprise entre sensiblement 30 et 70% molaire pour X=F ou Cl dans P1.said copolymer P being transparent, of amorphous nature and having a content of motif P2 of between substantially 30 and 70 mol% for X = F or Cl in P1.
Grâce à l'utilisation, dans les procédés connus, du copolymère mentionné ci-dessus, qui présente les propriétés optiques et thermomécaniques requises pour la fabrication de fibres optiques plastiques, ce copolymère étant incolore et transparent, soluble dans les solvants usuels (acétone, THF, acétate d'éthyle notamment), de température de transition vitreuse supérieure à 60° C, on peut obtenir des fibres optiques plastiques, notamment à gradient d'indice, ayant une
atténuation plus faible que celle des fibres obtenues à partir des polymères de l'art antérieur.Thanks to the use, in known processes, of the copolymer mentioned above, which has the optical and thermomechanical properties required for the manufacture of plastic optical fibers, this copolymer being colorless and transparent, soluble in the usual solvents (acetone, THF , ethyl acetate in particular), with a glass transition temperature above 60 ° C., plastic optical fibers can be obtained, in particular with an index gradient, having a weaker attenuation than that of fibers obtained from polymers of the prior art.
Les procédés selon l'invention s'appliquent aussi bien à la fabrication de fibres optiques à gradient d'indice qu'à celle de fibres à saut d'indice.The methods according to the invention apply as well to the production of index gradient optical fibers as to that of index jump fibers.
Le copolymère P peut être obtenu à partir de chlorotrifluoroéthylène ou de tétrafluoroéthylène, monomères fluorés industriels, et de carbonate de vinylène, monomère non halogène facilement accessible. Le copolymère contenant beaucoup de fluor et donc moins d'hydrogène que les polymères de l'art antérieur de type PMMA, ce qui conduit à une transparence accrue, et ayant une structure cyclique, ce qui conduit à une structure amorphe et donc à des propriétés de transmission optique améliorées, les fibres obtenues par le procédé selon l'invention sont particulièrement adaptées aux applications aux longueurs d'onde supérieures à 500 nm, typiquement dans les fenêtres de transmission se situant autour de 650, 850, 1300 et 1550 nm.The copolymer P can be obtained from chlorotrifluoroethylene or tetrafluoroethylene, industrial fluorinated monomers, and from vinylene carbonate, a readily accessible non-halogenated monomer. The copolymer containing a lot of fluorine and therefore less hydrogen than the polymers of the prior art of PMMA type, which leads to increased transparency, and having a cyclic structure, which leads to an amorphous structure and therefore to properties optical transmission fibers, the fibers obtained by the method according to the invention are particularly suitable for applications at wavelengths greater than 500 nm, typically in the transmission windows located around 650, 850, 1300 and 1550 nm.
De manière très avantageuse, dans un premier mode de réalisation, la présente invention propose un procédé de fabrication d'une fibre optique plastique à saut d'indice, dont l'indice varie de manière discontinue entre le centre et la périphérie de la fibre, ou à gradient d'indice dont l'indice varie continûment entre le centre et la périphérie de la fibre, à partir d'au moins ledit polymère P et d'au moins un diluant réactif D1 permettant de faire varier l'indice de réfraction de ladite fibre, ledit procédé comprenant les étapes suivantes :Very advantageously, in a first embodiment, the present invention provides a method of manufacturing a plastic optical fiber with index jump, the index of which varies discontinuously between the center and the periphery of the fiber, or with an index gradient, the index of which varies continuously between the center and the periphery of the fiber, from at least said polymer P and from at least one reactive diluent D1 making it possible to vary the refractive index of said fiber, said method comprising the following steps:
• préparation de deux compositions d'indice de réfraction différent, la différence d'indice de réfraction entre les deux compositions étant au moins de 5.10"3, comprenant chacune au moins le polymère P, l'une des compositions, dite première composition, comprenant en outre au moins le diluant réactif D1 , un amorceur de polymérisation radicalaire étant présent dans au moins l'une des compositions,
filage • réticulation du diluant réactif conduisant à une fibre optique plastique.• preparation of two compositions with different refractive index, the difference in refractive index between the two compositions being at least 5.10 "3 , each comprising at least polymer P, one of the compositions, known as the first composition, comprising in addition at least the reactive diluent D1, a radical polymerization initiator being present in at least one of the compositions, spinning • crosslinking of the reactive diluent leading to a plastic optical fiber.
Lorsque la fibre optique plastique est une fibre à gradient d'indice, ledit procédé comprend en outre, après l'étape de préparation desdites compositions, une étape de mélange actif des deux compositions afin d'obtenir la variation continue de l'indice de réfraction de la fibre optique, suivie du filage dudit mélange.When the plastic optical fiber is a gradient index fiber, said method further comprises, after the step of preparing said compositions, a step of active mixing of the two compositions in order to obtain the continuous variation of the refractive index optical fiber, followed by spinning of said mixture.
Avantageusement, la réticulation est une photo-réticulation et l'amorceur est un photo-amorceur. De manière avantageuse, la masse molaire du polymère P est comprise entre 1000 et 20000 g. moles"1 et le diluant réactif D1 a une masse molaire comprise entre 100 et 1000 g. moles"1. Ces choix limitent la viscosité de la composition et facilitent le filage.Advantageously, the crosslinking is a photo-crosslinking and the initiator is a photoinitiator. Advantageously, the molar mass of the polymer P is between 1000 and 20000 g. moles "1 and the reactive diluent D1 has a molar mass of between 100 and 1000 g. moles " 1 . These choices limit the viscosity of the composition and facilitate spinning.
De manière avantageuse encore, le diluant réactif D1 comprend au moins un groupement insaturé réactif vis-à-vis des UV choisi dans le groupe formé par les groupements vinyliques et les groupements acryliques.Also advantageously, the reactive diluent D1 comprises at least one unsaturated group reactive with respect to UV rays chosen from the group formed by vinyl groups and acrylic groups.
Un mélange actif selon le procédé de l'invention est un mélange que l'on aide à se former, c'est-à-dire qui ne se réalise pas seulement par diffusion ; ce mélange actif peut être obtenu de façon statique en forçant par un moyen de diffusion statique le mélange des deux compositions, le plus souvent par écoulement forcé, ou par un moyen dynamique qui réalise de façon active un tel mélange. Un tel procédé a l'avantage d'être rapide, notamment beaucoup plus rapide que si l'on utilise seulement la diffusion entre les compositions, et de permettre l'obtention d'un gradient de concentration et donc d'indice de réfraction continu et pratiquement régulier.An active mixture according to the process of the invention is a mixture which is helped to form, that is to say which is not produced only by diffusion; this active mixture can be obtained statically by forcing by a static diffusion means the mixture of the two compositions, most often by forced flow, or by dynamic means which actively produces such a mixture. Such a method has the advantage of being rapid, in particular much faster than if only the diffusion between the compositions is used, and of making it possible to obtain a concentration gradient and therefore a continuous refractive index and practically regular.
La cinétique de réticulation est généralement telle que, sous insolation maximale et transformation complète du photo-amorceur, le temps de gel est inférieur à 10 s, de préférence inférieur à 2 s. Selon le procédé de l'invention, le filage du mélange à gradient d'indice est suivi d'une réticulation photochimique ou thermique du diluant
réactif conduisant à l'obtention d'un réseau tridimensionnel réticulé. Ce processus permet avantageusement de figer au moins en partie les composants de la fibre optique plastique. La fibre optique plastique ainsi obtenue ainsi que son gradient d'indice possèdent par conséquent une stabilité dans le temps et une stabilité en température. Dans un tel cas, généralement au moins une des deux compositions comprend un monomère ; de plus, au moins l'une des deux compositions comprend au moins un amorceur de polymérisation radicalaire, et de préférence chacune des deux compositions comprend au moins un amorceur de polymérisation radicalaire. L'amorceur de polymérisation radicalaire est un composé qui permet de générer des radicaux amorceurs par décomposition thermique ou photo-chimique la réaction de réticulation.The crosslinking kinetics are generally such that, under maximum exposure and complete transformation of the photoinitiator, the gel time is less than 10 s, preferably less than 2 s. According to the process of the invention, the spinning of the index gradient mixture is followed by a photochemical or thermal crosslinking of the diluent reagent leading to the production of a cross-linked three-dimensional network. This process advantageously makes it possible to at least partially freeze the components of the plastic optical fiber. The plastic optical fiber thus obtained and its index gradient therefore have stability over time and stability in temperature. In such a case, generally at least one of the two compositions comprises a monomer; in addition, at least one of the two compositions comprises at least one radical polymerization initiator, and preferably each of the two compositions comprises at least one radical polymerization initiator. The radical polymerization initiator is a compound which makes it possible to generate initiator radicals by thermal or photochemical decomposition of the crosslinking reaction.
Selon un mode de réalisation, la seconde composition comprend au moins un diluant réactif D2 permettant lui aussi de faire varier l'indice de réfraction, le diluant réactif D2 étant d'indice de réfraction sensiblement différent de l'indice de réfraction de D1 , ayant une masse molaire comprise entre 100 et 1000 g. moles"1, et comprenant au moins un groupement insaturé réactif vis-à-vis des UV choisi dans le groupe formé par les groupements vinyliques et les groupements acryliques. De préférence, les diluants réactifs D1 et D2 sont de viscosités respectives pratiquement identiques et la proportion en masse du polymère P par rapport aux constituants de la composition est pratiquement constante pour chacune des compositions. Ainsi le procédé est plus facile à mettre en œuvre car la variation de la proportion en diluant(s) réactif(s) D1 et/ou D2, permettant principalement de moduler l'indice de réfraction, n'influence pas de façon significative la viscosité des compositions.According to one embodiment, the second composition comprises at least one reactive diluent D2 also making it possible to vary the refractive index, the reactive diluent D2 being of refractive index substantially different from the refractive index of D1, having a molar mass of between 100 and 1000 g. moles "1 , and comprising at least one UV-reactive unsaturated group chosen from the group formed by vinyl groups and acrylic groups. Preferably, the reactive diluents D1 and D2 have respective viscosities which are practically identical and the proportion by mass of the polymer P relative to the constituents of the composition is practically constant for each of the compositions, thus the process is easier to implement since the variation in the proportion of diluent (s) reactive (s) D1 and / or D2, mainly used to modulate the refractive index, does not significantly influence the viscosity of the compositions.
Selon un mode de réalisation du procédé selon l'invention, dans le cas de la fibre optique à gradient d'indice, le mélange des deux compositions est réalisé à une température telle que la viscosité à 20° C de chacune des deux compositions est comprise entre 1 et 25 Pa.s, de préférence entre 1 et 15 Pa.s. Ceci permet avantageusement de faciliter la
mise en œuvre du procédé selon l'invention, car une telle viscosité permet de procéder au mélange de compositions relativement fluides.According to one embodiment of the method according to the invention, in the case of optical fiber with an index gradient, the mixing of the two compositions is carried out at a temperature such that the viscosity at 20 ° C. of each of the two compositions is included between 1 and 25 Pa.s, preferably between 1 and 15 Pa.s. This advantageously makes it possible to facilitate the implementation of the method according to the invention, because such a viscosity makes it possible to mix relatively fluid compositions.
Selon un mode de réalisation du procédé selon l'invention, le filage est réalisé à une température telle que la viscosité de chacune des deux compositions est supérieure à 500 mPa.s, de préférence supérieure à 1000 mPa.s.According to one embodiment of the method according to the invention, the spinning is carried out at a temperature such that the viscosity of each of the two compositions is greater than 500 mPa.s, preferably greater than 1000 mPa.s.
Les groupements réactifs portés par les constituants D1 et D2 sont choisis dans le groupe formé par les groupements vinyliques et les groupements acryliques, c'est-à-dire choisis notamment parmi les acrylates, les methacrylates, les ethers vinyliques ou les ethers de propenyle, ces groupements pouvant être au moins partiellement halogènes, le plus souvent fluorés et/ou chlorés.The reactive groups carried by the constituents D1 and D2 are chosen from the group formed by vinyl groups and acrylic groups, that is to say chosen in particular from acrylates, methacrylates, vinyl ethers or propenyl ethers, these groups can be at least partially halogenated, most often fluorinated and / or chlorinated.
Dans un mode de réalisation du procédé selon l'invention, tout composant d'une des compositions est un matériau au moins partiellement halogène, le plus souvent fluoré et/ou chloré.In one embodiment of the method according to the invention, any component of one of the compositions is an at least partially halogenated material, most often fluorinated and / or chlorinated.
Selon une variante du procédé selon l'invention, dans le cas de la présence de diluant réactif D2 dans la seconde composition, l'un des deux diluants réactifs D1 ou D2 est au moins partiellement fluoré et l'autre des deux diluants réactifs D2 ou D1 est au moins partiellement chloré ou chloro-fluoré, et donc d'indice de réfraction sensiblement supérieur à celui du monomère au moins partiellement fluoré.According to a variant of the process according to the invention, in the case of the reactive diluent D2 in the second composition, one of the two reactive diluents D1 or D2 is at least partially fluorinated and the other of the two reactive diluents D2 or D1 is at least partially chlorinated or chloro-fluorinated, and therefore has a refractive index substantially higher than that of the at least partially fluorinated monomer.
Dans un deuxième mode de réalisation, la présente invention propose un procédé de fabrication d'une fibre optique plastique à gradient d'indice dont l'indice varie continûment entre le centre et la périphérie de la fibre, à partir d'au moins ledit polymère P et d'au moins un dopant D permettant de faire varier l'indice de réfraction de ladite fibre, l'indice de réfraction dudit dopant D étant supérieur à celui dudit polymère P, ledit procédé comprenant les étapes suivantes : • fusion du polymère P dans un tube • mise en rotation dudit tube autour de son axe
• refroidissement dudit tube de manière à former à l'intérieur dudit tube un corps tubulaire en polymère PIn a second embodiment, the present invention provides a method for manufacturing a plastic optical fiber with an index gradient, the index of which varies continuously between the center and the periphery of the fiber, from at least said polymer. P and at least one dopant D making it possible to vary the refractive index of said fiber, the refractive index of said dopant being greater than that of said polymer P, said method comprising the following steps: • melting of polymer P in a tube • rotation of said tube around its axis • cooling of said tube so as to form inside said tube a tubular body of polymer P
• introduction dudit dopant D dans ledit corps tubulaire formé par le polymère P • chauffage et mise en rotation dudit tube autour de son axe de manière à faire diffuser thermiquement ledit dopant D à travers ledit polymère P et à former un corps tubulaire de polymère P dopé• introduction of said dopant D into said tubular body formed by polymer P • heating and rotation of said tube around its axis so as to cause said dopant D to thermally diffuse through said polymer P and to form a tubular body of doped polymer P
• refroidissement pour obtenir une préforme tubulaire• cooling to obtain a tubular preform
• étirage de ladite préforme tubulaire reliée à une pompe à vide pour former une fibre optique plastique.• stretching of said tubular preform connected to a vacuum pump to form a plastic optical fiber.
Dans un troisième mode de réalisation, la présente invention propose un procédé de fabrication d'une fibre optique plastique à saut d'indice dont l'indice varie de manière discontinue entre le centre et la périphérie de la fibre, à partir d'au moins ledit polymère P, ledit polymère P étant filé à l'état fondu et simultanément revêtu d'une résine photoréticulable d'indice de réfraction inférieur à celui du polymère P, qui est ensuite photopolymérisée.In a third embodiment, the present invention provides a method of manufacturing a plastic index-hopping optical fiber, the index of which varies discontinuously between the center and the periphery of the fiber, from at least said polymer P, said polymer P being spun in the molten state and simultaneously coated with a photocrosslinkable resin with a refractive index lower than that of polymer P, which is then photopolymerized.
Enfin, dans un quatrième mode de réalisation, la présente invention propose un procédé de fabrication d'une fibre optique plastique à saut d'indice dont l'indice varie de manière discontinue entre le centre et la périphérie de la fibre, à partir d'au moins ledit polymère P, par coextrusion dudit polymère P avec un autre polymère d'indice de réfraction inférieur à celui dudit polymère P.Finally, in a fourth embodiment, the present invention provides a method of manufacturing a plastic optical fiber with index jump, the index of which varies discontinuously between the center and the periphery of the fiber, starting from at least said polymer P, by coextrusion of said polymer P with another polymer of refractive index lower than that of said polymer P.
Le procédé selon l'invention peut bien entendu être également mis en œuvre pour la fabrication de guides d'ondes optiques.The method according to the invention can of course also be implemented for the manufacture of optical waveguides.
La présente invention concerne également une fibre optique plastique à gradient d'indice obtenue par le procédé selon l'invention, ainsi qu'un guide d'ondes optique obtenu par ce procédé.The present invention also relates to a plastic optical fiber with an index gradient obtained by the method according to the invention, as well as an optical waveguide obtained by this method.
D'autres caractéristiques et avantages de la présente invention apparaîtront dans la description suivante d'une mode de réalisation de l'invention, donné à titre illustratif et nullement limitatif.
Dans les figures suivantes :Other characteristics and advantages of the present invention will appear in the following description of an embodiment of the invention, given by way of illustration and in no way limitative. In the following figures:
- la figure 1 représente schématiquement un dispositif permettant de mettre en œuvre le procédé selon l'invention.- Figure 1 schematically shows a device for implementing the method according to the invention.
- la figure 2 représente une vue schématique du profil d'indice d'une fibre optique obtenue au moyen du dispositif de la figure 1- Figure 2 shows a schematic view of the index profile of an optical fiber obtained by means of the device of Figure 1
- la figure 3 montre les spectres d'atténuation d'une fibre optique plastique à gradient d'indice obtenue à partir de procédés de l'art antérieur et d'un procédé selon l'un des modes de réalisation de l'invention. Dans toutes ces figures, les éléments communs portent les mêmes numéros de référence.FIG. 3 shows the attenuation spectra of a plastic optical fiber with an index gradient obtained from methods of the prior art and from a method according to one of the embodiments of the invention. In all these figures, the common elements have the same reference numbers.
Selon le procédé de l'invention, on prépare deux compositions, comprenant chacune un copolymère P. L'une de ces compositions comprend en outre au moins un diluant réactif D1 , qui est de préférence un monomère. Eventuellement, l'autre composition comprend au moins un diluant réactif D2, qui est également de préférence un monomère. La concentration de D1 est différente dans chacune des deux compositions, ce qui donne un indice de réfraction différent à chaque composition. Les deux valeurs ainsi obtenues d'indice de réfraction constituent le maximum et le minimum de la courbe de gradient d'indice de forme parabolique que l'on cherche à obtenir pour la fibre optique plastique issue du procédé (voir figure 2).According to the process of the invention, two compositions are prepared, each comprising a copolymer P. One of these compositions further comprises at least one reactive diluent D1, which is preferably a monomer. Optionally, the other composition comprises at least one reactive diluent D2, which is also preferably a monomer. The concentration of D1 is different in each of the two compositions, which gives a different refractive index to each composition. The two values of refraction index thus obtained constitute the maximum and the minimum of the parabolic index gradient gradient curve that one seeks to obtain for the plastic optical fiber resulting from the process (see FIG. 2).
Le copolymère P utilisé dans le procédé de l'invention comprend les unités répétitives P1 et P2 représentées ci-dessous.The copolymer P used in the process of the invention comprises the repeating units P1 and P2 shown below.
L'unité P1 est issue de la polymérisation de i monomères M1 et l'unité P2 est issue de la polymérisation de j monomères M2. The unit P1 is derived from the polymerization of i monomers M1 and the unit P2 is derived from the polymerization of j monomers M2.
Le monomère M1 est un monomère fluoré représenté par la formule générale suivante : CF2=CFX, dans laquelle X est soit : - un atome de fluor, auquel cas M1 est le tétrafluoroéthylène ; - un atome de chlore, auquel cas M1 est le chlorotrifluoroéthylène.The monomer M1 is a fluorinated monomer represented by the following general formula: CF 2 = CFX, in which X is either: - a fluorine atom, in which case M1 is tetrafluoroethylene; - a chlorine atom, in which case M1 is chlorotrifluoroethylene.
Les entités répétitives P1 peuvent être issues d'un mélange de monomères de formule M1.The repeating entities P1 can come from a mixture of monomers of formula M1.
Le comonomère M2 donnant lieu aux entités répétitives P2 est le carbonate de vinylène de formule suivante:The comonomer M2 giving rise to the repeating entities P2 is the vinylene carbonate of the following formula:
H HH H
\ /\ /
C=CC = C
/ \ o o/ \ o o
II oII o
M2M2
Comme procédé permettant d'obtenir le copolymère P, on peut utiliser tout procédé de polymérisation connu de l'homme de l'art utilisant un milieu solvant, en suspension dans l'eau ou en emulsion par exemple. On préférera généralement travailler en milieu solvant afin de contrôler l'exothermicité de la polymérisation et favoriser un mélange intime des différents monomères.As a process making it possible to obtain the copolymer P, any polymerization process known to a person skilled in the art using a solvent medium, in suspension in water or in emulsion for example, can be used. It is generally preferable to work in a solvent medium in order to control the exothermicity of the polymerization and to favor an intimate mixture of the different monomers.
Parmi les solvants couramment utilisés, on peut citer l'acétate d'ethyle, de méthyle ou encore de butyle, les solvants chlorofluorés comme le F141b® (CFCl2-CH3) ou le F113® (CF2Cl-CFCl2).Among the solvents commonly used, there may be mentioned ethyl, methyl or butyl acetate, chlorofluorinated solvents such as F141b® (CFCl 2 -CH 3 ) or F113® (CF 2 Cl-CFCl 2 ).
Comme amorceur de polymérisation radicalaire, on peut employer des générateurs de radicaux libres tels que les dérivés peroxydes, hydroperoxydes, percarbonate ou encore des composés diazoïques comme
l'azobisisobutyronitrile (AlBN). On peut également, dans les cas de procédés menés en milieu aqueux, utiliser des générateurs de radicaux libres inorganiques comme les persulfates ou des combinaisons dites rédox. La température de polymérisation est dictée, en général, par la vitesse de décomposition de l'amorceur choisi et est, en général, comprise entre 0 et 200 °C de préférence entre 40 et 120° C.As a radical polymerization initiator, it is possible to use free radical generators such as peroxide, hydroperoxide, percarbonate derivatives or even diazo compounds such as azobisisobutyronitrile (AlBN). It is also possible, in the case of processes carried out in an aqueous medium, to use inorganic free radical generators such as persulfates or so-called redox combinations. The polymerization temperature is dictated, in general, by the rate of decomposition of the selected initiator and is, in general, between 0 and 200 ° C, preferably between 40 and 120 ° C.
La pression est, en général, comprise entre la pression atmosphérique et une pression de 50 bars, plus particulièrement entre 2 bars et 20 bars. Afin de mieux contrôler la composition du copolymère P, il est également possible d'introduire en tout ou partie les monomères ainsi que l'initiateur de polymérisation de façon continue ou par fraction au cours de la polymérisation.The pressure is, in general, between atmospheric pressure and a pressure of 50 bars, more particularly between 2 bars and 20 bars. In order to better control the composition of the copolymer P, it is also possible to introduce all or part of the monomers as well as the polymerization initiator continuously or by fraction during the polymerization.
Le copolymère P utilisé dans le procédé selon l'invention possède une température de transition vitreuse (Tg) située entre 60 et 160°C, de préférence entre 80 et 140° C. Cette température de transition vitreuse est principalement liée à la teneur en motifs P2 présents dans le copolymère.The copolymer P used in the process according to the invention has a glass transition temperature (Tg) situated between 60 and 160 ° C, preferably between 80 and 140 ° C. This glass transition temperature is mainly linked to the content of units P2 present in the copolymer.
La transparence du polymère obtenu dépend également de la teneur en motifs P2. La teneur en motif P2, unité répétitive issue de la polymérisation de monomères M2, peut varier dans le copolymère en fonction de la nature de X dans P1. Pour X=F ou Cl dans P1 , la teneur en motif P2 dans le copolymère est comprise entre sensiblement 30 et 70% molaire.The transparency of the polymer obtained also depends on the content of units P2. The content of motif P2, repeating unit resulting from the polymerization of monomers M2, can vary in the copolymer depending on the nature of X in P1. For X = F or Cl in P1, the content of motif P2 in the copolymer is between substantially 30 and 70 mol%.
Sans porter préjudice à l'invention, on peut également introduire un troisième monomère lors de la polymérisation à condition que sa teneur reste inférieure à 15 % molaire dans le copolymère formé.Without prejudice to the invention, it is also possible to introduce a third monomer during the polymerization provided that its content remains less than 15 mol% in the copolymer formed.
Le polymère P du procédé selon l'invention a une masse molaire moyenne en nombre (Mn) comprise entre 500 et 106 g. moles"1 et de préférence entre 103 et 104 g. moles"1. Nous allons maintenant illustrer l'invention en présentant des exemples de réalisation du copolymère P.
Les réactifs, initiateurs et solvants utilisés sont abrégés : CTFE : chlorotrifluoroéthylène CF2=CFCl TFE : tétrafluoroéthylène CF2=CF2 VCA : carbonate de vinylène TBPP : perpivalate de tertiobutyle, à 75% en masse dans l'isododécane F141b® : 1 ,1,1 -dichlorofluoroéthaneThe polymer P of the process according to the invention has a number-average molar mass (Mn) of between 500 and 10 6 g. moles "1 and preferably between 10 3 and 10 4 g. moles " 1 . We will now illustrate the invention by presenting exemplary embodiments of the copolymer P. The reagents, initiators and solvents used are abbreviated: CTFE: chlorotrifluoroethylene CF 2 = CFCl TFE: tetrafluoroethylene CF 2 = CF2 VCA: vinylene carbonate TBPP: tertiobutyl perpivalate, at 75% by mass in isododecane F141b®: 1, 1 , 1 -dichlorofluoroethane
Les Mn (masses molaires moyennes en nombre) sont déterminées par analyse CES (chromatographie d'exclusion stérique). On utilise un appareillage de la société Spectra Physic « Winner Station ». La détection est effectuée par indice de réfraction. La colonne est une colonne mixed CThe Mn (number-average molar masses) are determined by CES analysis (steric exclusion chromatography). An apparatus from the company Spectra Physic "Winner Station" is used. Detection is carried out by refractive index. The column is a mixed C column
PL gel de 5 microns de la société Polymer Laboratory et le solvant utilisé est le THF à un débit de 0,8 ml/min. Les masses molaires en nombre (Mn) sont exprimées en g. moles"1 par rapport à un standard polystyrène. Les Tg (températures de transition vitreuse) sont déterminées par calorimétrie différentielle à balayage (DSC en anglais). On effectue une première montée en température à 20°C/min suivie d'un refroidissement puis une deuxième montée en température au cours de laquelle sont relevées les Tg ou les Tf (températures de fusion). La plage de température est de 50°C à 200°C si la Tg est supérieure à 60°C.PL gel of 5 microns from the company Polymer Laboratory and the solvent used is THF at a flow rate of 0.8 ml / min. The molar masses in number (Mn) are expressed in g. moles "1 relative to a polystyrene standard. The Tg (glass transition temperatures) are determined by differential scanning calorimetry (DSC in English). A first temperature rise is carried out at 20 ° C./min followed by cooling and then a second rise in temperature during which the Tg or Tf (melting temperatures) are recorded The temperature range is from 50 ° C to 200 ° C if the Tg is greater than 60 ° C.
Les taux de chlore sont déterminés de façon classique par minéralisation en bombe de PARR avec Na2O2 puis dosage des chlorures par argentimétrie.The chlorine levels are determined in a conventional manner by mineralization in a PARR bomb with Na 2 O 2 followed by determination of the chlorides by argentimetry.
Exemple 1Example 1
[M1/M2 : CTFE/VCA][M1 / M2: CTFE / VCA]
On opère dans un réacteur en acier inoxydable de 160 ml, purgé deux à trois fois avec 5 bars d'azote. On introduit par aspiration dans le réacteur sous vide (environ 100 mbars de pression), 50 ml d'une solution de F141b® contenant 0,6 ml (soit 2,25 mmoles) d'amorceur TBPP et 8,53 gThe operation is carried out in a 160 ml stainless steel reactor, purged two to three times with 5 bars of nitrogen. 50 ml of an F141b® solution containing 0.6 ml (or 2.25 mmol) of TBPP initiator and 8.53 g are introduced by suction into the vacuum reactor (approximately 100 mbar of pressure).
(soit 99 mmoles) de VCA. On introduit ensuite 11 g (soit 94,5 mmoles) de
CTFE. Le milieu réactionnel est chauffé à 80 °C pendant 2h30 sous agitation avec une pression initiale d'environ 10 bars. Après réaction, le contenu de l'autoclave est évaporé partiellement, précipité à l'heptane puis séché sous vide. On obtient ainsi 16,2 g de copolymère soluble dans les solvants usuels (acétone, THF). Les analyses réalisées sur le copolymère obtenu dans l'exemple 1 indiquent un rapport molaire P1 /P2 de 47/53, une Mn de 7400 g. moles"1 et une Tg de 120°C. Par mise en solution dans l'acétate d'ethyle et évaporation, on obtient un film incolore transparent.(i.e. 99 mmol) of VCA. Then 11 g (94.5 mmol) of CTFE. The reaction medium is heated at 80 ° C for 2 h 30 min with stirring with an initial pressure of about 10 bar. After reaction, the contents of the autoclave are partially evaporated, precipitated with heptane and then dried under vacuum. 16.2 g of copolymer soluble in the usual solvents (acetone, THF) are thus obtained. The analyzes carried out on the copolymer obtained in Example 1 indicate a P1 / P2 molar ratio of 47/53, an Mn of 7400 g. moles "1 and a Tg of 120 ° C. By dissolving in ethyl acetate and evaporation, a transparent colorless film is obtained.
Exemple 2 [M1/M2 : CTFE/VCA]Example 2 [M1 / M2: CTFE / VCA]
On opère de la même manière que dans l'exemple 1 avec les mêmes réactifs et les mêmes proportions en employant le solvant acétate d'ethyle à la place du F141 b®. En fin de réaction, on obtient une solution de polymère dans l'acétate d'ethyle. Le solvant est évaporé jusqu'à obtenir un volume d'environ 20 ml puis on précipite le produit de la réaction au n-heptane. Le polymère précipité est filtré puis séché sous vide à 60° C. On obtient 10 g d'un copolymère incolore, transparent, soluble dans le THF ou l'acétone. Le rapport molaire P1 /P2 est de 49/51 et la Tg de 106°C.The procedure is the same as in Example 1 with the same reagents and the same proportions using the ethyl acetate solvent in place of F141 b®. At the end of the reaction, a solution of polymer in ethyl acetate is obtained. The solvent is evaporated until a volume of about 20 ml is obtained and then the reaction product is precipitated with n-heptane. The precipitated polymer is filtered and then dried under vacuum at 60 ° C. 10 g of a colorless, transparent copolymer, soluble in THF or acetone, are obtained. The P1 / P2 molar ratio is 49/51 and the Tg is 106 ° C.
On prélève 1 g de ce copolymère que l'on met en solution dans 3 ml d'acétate d'ethyle. La solution ainsi obtenue est parfaitement limpide. On dépose cette solution dans un cristallisoir plat de 7 cm de diamètre et on laisse évaporer le solvant pendant 3 jours à température et atmosphère ambiantes. Le film ainsi obtenu est parfaitement transparent et limpide.1 g of this copolymer is taken which is dissolved in 3 ml of ethyl acetate. The solution thus obtained is perfectly clear. This solution is deposited in a flat crystallizer 7 cm in diameter and the solvent is left to evaporate for 3 days at ambient temperature and atmosphere. The film thus obtained is perfectly transparent and clear.
Exemples 3 à 7Examples 3 to 7
On réalise des exemples comparatifs 3, 5, 6 et 7 ainsi qu'un exemple 4 en opérant de la même manière qu'à l'exemple 2 avec les quantités de réactifs CTFE et VCA indiquées dans le TABLEAU 1 ci-après.
Dans les exemples et comparatifs du TABLEAU 1 sont mis en jeu au début de la réaction x mmoles de CTFE et y mmoles de VCA, x et y ayant les valeurs suivantes selon les exemples :Comparative examples 3, 5, 6 and 7 are carried out, as well as example 4, operating in the same manner as in example 2 with the amounts of CTFE and VCA reagents indicated in TABLE 1 below. In the examples and comparatives of TABLE 1 are brought into play at the start of the reaction x mmoles of CTFE and y mmoles of VCA, x and y having the following values according to the examples:
Exemple 1 : x = 94,5 et y = 99Example 1: x = 94.5 and y = 99
Exemple 2 : x = 95 et y = 98Example 2: x = 95 and y = 98
Exemple comparatif 3 : x = 186 et y = 40Comparative example 3: x = 186 and y = 40
Exemple 4 : x = 86 et y = 174Example 4: x = 86 and y = 174
Exemple comparatif 5 : x = 181 et y = 10,5Comparative example 5: x = 181 and y = 10.5
Exemple comparatif 6 : x = 43 et y = 174Comparative example 6: x = 43 and y = 174
Exemple comparatif 7 : x = 0 et y = 180.Comparative example 7: x = 0 and y = 180.
Les rapports molaires P1 /P2, le rendement de polymère obtenu en % molaire, l'aspect de la solution de polymère obtenue à l'issue de la réaction de polymérisation de M1 et M2 et l'aspect du film dudit polymère sont reportés dans le TABLEAU 1 pour les exemples 1 à 7.The P1 / P2 molar ratios, the polymer yield obtained in molar%, the appearance of the polymer solution obtained at the end of the polymerization reaction of M1 and M2 and the appearance of the film of said polymer are reported in the TABLE 1 for examples 1 to 7.
TABLEAU 1TABLE 1
(1 ) P1 ayant pour comonomère M1 le CTFE et P2 ayant pour comonomère M2 le VCA.
(2) solution : 1 g de polymère dans 3 ml d'acétate d'ethyle .(1) P1 having as comonomer M1 the CTFE and P2 having as comonomer M2 the VCA. (2) solution: 1 g of polymer in 3 ml of ethyl acetate.
On constate que pour les exemples 1 , 2 et 4 comprenant des rapports molaires P1 /P2 compris entre sensiblement 70/30 et 30/70 avec M1 = CTFE et M2 = VCA, la solution de copolymère P obtenue est limpide et le film de copolymère obtenu après évaporation du solvant de ladite solution est un solide transparent. On constate que dans le cas des exemples comparatifs 3, 5, 6 et 7, comprenant des rapports molaires P1 /P2 situés en dehors de la plage citée précédemment, le film de copolymère est un solide non transparent.It is noted that for Examples 1, 2 and 4 comprising molar ratios P1 / P2 of between approximately 70/30 and 30/70 with M1 = CTFE and M2 = VCA, the solution of copolymer P obtained is clear and the film of copolymer obtained after evaporation of the solvent from said solution is a transparent solid. It is noted that in the case of Comparative Examples 3, 5, 6 and 7, comprising P1 / P2 molar ratios situated outside the range mentioned above, the copolymer film is a non-transparent solid.
Exemple 8Example 8
[M1/M2 : TFE/VCA][M1 / M2: TFE / VCA]
On opère de la même manière qu'à l'exemple 2 mais avec 7 g (soit 81,3 mmoles) de VCA et 11 g (soit 110 mmoles) de TFE à la place du CTFE. On obtient 14,6 g de copolymère. Le copolymère est très soluble dans l'acétone ou le THF. Par évaporation de l'acétone, on obtient un film incolore, transparent. L'analyse RMN 19F indique un rapport molaire P1 /P2 de 70/30. La Tg du copolymère est de 82° C (analyse DSC).The procedure is the same as in Example 2 but with 7 g (or 81.3 mmol) of VCA and 11 g (or 110 mmol) of TFE in place of the CTFE. 14.6 g of copolymer are obtained. The copolymer is very soluble in acetone or THF. By evaporation of the acetone, a colorless, transparent film is obtained. 19 F NMR analysis indicates a P1 / P2 molar ratio of 70/30. The Tg of the copolymer is 82 ° C (DSC analysis).
D'autres essais ont également été menés avec M1 = TFE et M2 = VCA. On a pu constater que pour des rapports molaires P1 /P2 compris entre sensiblement 70/30 et 30/70, on obtenait des films de copolymères sensiblement transparents.Other trials have also been carried out with M1 = TFE and M2 = VCA. It has been observed that for molar ratios P1 / P2 of between substantially 70/30 and 30/70, films of substantially transparent copolymers are obtained.
Une fois le copolymère P obtenu par exemple selon l'un des exemples décrits ci-dessus, on prépare les deux compositions C1 et C2 permettant de conduire à la fabrication d'une fibre optique selon l'invention par un procédé de type UV.Once the copolymer P obtained for example according to one of the examples described above, the two compositions C1 and C2 are prepared, making it possible to produce an optical fiber according to the invention by a UV type process.
On fabrique deux compositions différentes, comportant un photo-amorceur commercial, le copolymère réactif P de l'exemple 1, 2 ou 3 ci-dessus, et un diluant réactif composé de deux monomères en proportions différentes selon la composition, les deux monomères étant (D1 ) et (D2)
Le photo-amorceur peut être par exemple une α-hydroxycétone (IRGACURE 184, DAROCUR 1173), une mono acyl phosphine (DAROCUR TPO) ou une bis acyl phosphine (IRGACURE 819).Two different compositions are produced, comprising a commercial photoinitiator, the reactive copolymer P of Example 1, 2 or 3 above, and a reactive diluent composed of two monomers in different proportions according to the composition, the two monomers being ( D1) and (D2) The photoinitiator may for example be an α-hydroxyketone (IRGACURE 184, DAROCUR 1173), a mono acyl phosphine (DAROCUR TPO) or a bis acyl phosphine (IRGACURE 819).
D1 et D2 peuvent être des monomères possédant au moins une fonction acrylique, methacrylique, α-fluoroacrylique, α,β-difluoroacrylique ou vinylique comportant des groupements halogènes (fluorés et chlorés).D1 and D2 can be monomers having at least one acrylic, methacrylic, α-fluoroacrylic, α, β-difluoroacrylic or vinyl function comprising halogen groups (fluorinated and chlorinated).
Le TABLEAU 2 ci-après résume la constitution et les propriétés des compositions C1 et C2, préparées à partir du mélange de copolymère P de l'exemple 1 , le diluant réactif D1 étant l'acrylate de trifluoroéthyle (dont l'homopolymere à 20° C a un indice de réfraction égale à 1 ,407), et le diluant réactif D2 étant le méthacrylate de trifluoroéthyle (dont l'homopolymere à 20°C a un indice de réfraction égal à 1 ,437). Le photo- amorceur est de la classe des bis acyl phosphines (BAPO - IRGACURE 819). Les quantités sont calculées pour 700 grammes de composition.TABLE 2 below summarizes the constitution and properties of compositions C1 and C2, prepared from the mixture of copolymer P of Example 1, the reactive diluent D1 being trifluoroethyl acrylate (including the homopolymer at 20 ° C has a refractive index equal to 1.407), and the reactive diluent D2 being trifluoroethyl methacrylate (the homopolymer of which at 20 ° C. has a refractive index equal to 1.437). The photoinitiator is from the class of bis acyl phosphines (BAPO - IRGACURE 819). The quantities are calculated for 700 grams of composition.
TABLEAU 2TABLE 2
On voit que le rapport, en % poids, du copolymère P sur la somme des constituants de chaque composition est constant, tandis qu'au sein du diluant réactif la proportion relative, en % massique de D1 par rapport à la somme de D1 et D2, varie d'une composition à l'autre. Ceci permet de contrôler la viscosité des deux compositions tout en faisant varier l'indice de réfraction de chacune de ces compositions . Selon le procédé de l'invention, pour réaliser une fibre à gradient d'indice, on crée la variation d'indice continue par réalisation d'un mélange actif des deux compositions C1 et C2 de départ. Pour cela, la mise en
œuvre du procédé selon l'invention se fait par un moyen de mélange qui peut être un mélangeur de type statique ou dynamique. Cette mise en œuvre est expliquée en détail dans le document EP-1 067 222 qui est incorporé ici par référence. On ne reviendra donc pas plus ici sur le fonctionnement du mélangeur statique ou dynamique utilisé dans le procédé selon l'invention, et l'on se contentera de décrire simplement le procédé de l'invention dans sa mise en œuvre à l'aide de l'un des mélangeurs statiques décrits dans le document EP-1 067 222.It can be seen that the ratio, in% by weight, of the copolymer P to the sum of the constituents of each composition is constant, while within the reactive diluent the relative proportion, in% by mass of D1 relative to the sum of D1 and D2 , varies from composition to composition. This makes it possible to control the viscosity of the two compositions while varying the refractive index of each of these compositions. According to the method of the invention, to produce a fiber with an index gradient, the continuous index variation is created by producing an active mixture of the two starting compositions C1 and C2. For this, the implementation The process according to the invention is carried out by a mixing means which can be a static or dynamic type mixer. This implementation is explained in detail in document EP-1 067 222 which is incorporated here by reference. We will therefore not return here more to the operation of the static or dynamic mixer used in the method according to the invention, and we will be content to simply describe the method of the invention in its implementation using the 'one of the static mixers described in document EP-1 067 222.
La figure 1 représente une vue en coupe très schématique, dans un plan comprenant un axe central X, d'un dispositif de fabrication d'une fibre optique selon le procédé de l'invention.FIG. 1 represents a very schematic sectional view, in a plane comprising a central axis X, of a device for manufacturing an optical fiber according to the method of the invention.
Le dispositif 10 comprend un mélangeur 1 statique. Les compositions C1 et C2 du tableau ci-dessus y sont mélangées.The device 10 comprises a static mixer 1. The compositions C1 and C2 of the table above are mixed there.
Le mélangeur 1 comporte deux cylindres concentriques 3 et 4 servant de réservoirs aux compositions C1 et C2. C'est l'enceinte cylindrique 8 du mélangeur 1 qui sert de réservoir 4 à la composition C2. La composition C1 de plus fort indice de réfraction est placée dans le réservoir central 3.The mixer 1 comprises two concentric cylinders 3 and 4 serving as reservoirs for the compositions C1 and C2. It is the cylindrical enclosure 8 of the mixer 1 which serves as a reservoir 4 for the composition C2. The composition C1 with the highest refractive index is placed in the central reservoir 3.
L'enceinte 8 comprend une fermeture supérieure étanche 8d qui comporte deux entrées respectives 8g et 8f permettant d'assurer une pression contrôlée dans chacun des réservoirs respectifs 3 et 4, par exemple au moyen de deux pompes volumétriques (non représentées). Ainsi une pression contrôlée peut être appliquée sur les deux compositions C1 et C2 afin d'obtenir un écoulement identique si les deux compositions C1 et C2 ont la même viscosité. Mais il est aussi possible d'appliquer des pressions contrôlées différentes pour les ouvertures 8f et 8g, par exemple si l'on veut un écoulement différent pour chaque composition C1 ou C2 dans le cas de deux compositions C1 et C2 de viscosités différentes. L'enceinte 8 comprend aussi une zone 8e où les deux réservoirs 3 et 4 sont concentriques, isolés l'un de l'autre, ainsi qu'une zone 8a dont la limite supérieure est le bas du réservoir central 3 et dont la limite inférieure est
le bas du réservoir périphérique 4. La zone 8a correspond à une zone de mélange des deux compositions C1 et C2 par le mélangeur 1 , à savoir un ensemble 2 de plaques (2a, 2b) superposées et perforées de trous 12. L'enceinte 8 comprend encore une zone conique 8b où se produit une variation homothétique de la section, et enfin une zone calibrée 8c comprenant une filière 15, qui donne l'ordre de grandeur désiré au diamètre d'une fibre optique plastique à gradient d'indice 6 obtenue. La fiière 15 est une pièce rapportée, ce qui permet de changer aisément de calibrage sans avoir à changer de mélangeur 1. Le mélangeur 1 comporte dans sa zone 8a au moins deux, et ici sept, plaques (2a, 2b) perforées superposées les unes au dessus des autres. Cet ensemble 2 de plaques (2a, 2b) est placé à l'extrémité inférieure du réservoir central 3 de manière à assurer un mélange radial des compositions C1 et C2. On obtient un mélange 5 présentant un gradient de concentrations des compositions C1 et C2, dans la zone 8a. Le mélange 5 se forme grâce à la superposition des plaques (2a, 2b). Chaque plaque 2a (respectivement 2b) comporte des trous 12, généralement disposés en opposition les uns par rapport aux autres d'une plaque 2a à une plaque voisine 2b (respectivement d'une plaque 2b à une plaque voisine 2a). Dans la représentation de la figure 1 , il existe deux types de plaques, les plaques 2a, au nombre de quatre, et les plaques 2b, au nombre de trois, chacune des plaques 2a ou 2b comportant approximativement le même nombre de trous 12.The enclosure 8 comprises a sealed upper closure 8d which has two respective inlets 8g and 8f making it possible to ensure a controlled pressure in each of the respective tanks 3 and 4, for example by means of two positive displacement pumps (not shown). Thus a controlled pressure can be applied to the two compositions C1 and C2 in order to obtain an identical flow if the two compositions C1 and C2 have the same viscosity. However, it is also possible to apply different controlled pressures for the openings 8f and 8g, for example if a different flow is desired for each composition C1 or C2 in the case of two compositions C1 and C2 of different viscosities. The enclosure 8 also includes a zone 8e where the two tanks 3 and 4 are concentric, isolated from each other, as well as a zone 8a whose upper limit is the bottom of the central tank 3 and whose lower limit East the bottom of the peripheral tank 4. Zone 8a corresponds to a zone for mixing the two compositions C1 and C2 by the mixer 1, namely a set 2 of plates (2a, 2b) superimposed and perforated with holes 12. The enclosure 8 further includes a conical area 8b where a homothetic variation of the section occurs, and finally a calibrated area 8c comprising a die 15, which gives the desired order of magnitude to the diameter of a plastic optical fiber with an index gradient 6 obtained . The fiiere 15 is an attached part, which makes it possible to easily change the calibration without having to change the mixer 1. The mixer 1 comprises in its zone 8a at least two, and here seven, perforated plates (2a, 2b) superposed one on the other above the others. This set 2 of plates (2a, 2b) is placed at the lower end of the central reservoir 3 so as to ensure a radial mixing of the compositions C1 and C2. A mixture 5 is obtained having a concentration gradient of compositions C1 and C2, in zone 8a. The mixture 5 is formed by the superposition of the plates (2a, 2b). Each plate 2a (respectively 2b) has holes 12, generally arranged in opposition with respect to each other from a plate 2a to an adjacent plate 2b (respectively from a plate 2b to an adjacent plate 2a). In the representation of FIG. 1, there are two types of plates, plates 2a, four in number, and plates 2b, three in number, each of plates 2a or 2b having approximately the same number of holes 12.
Le mélange 5 ainsi obtenu est amené à la filière 15 calibrée de la zone 8c de l'enceinte 8 par la zone conique 8b dont la limite supérieure est l'extrémité inférieure de la dernière plaque 2a. Cette variation homothétique permet de conserver la forme de la variation de concentration des compositions C1 et C2.The mixture 5 thus obtained is brought to the calibrated die 15 from the zone 8c of the enclosure 8 by the conical zone 8b, the upper limit of which is the lower end of the last plate 2a. This homothetic variation makes it possible to preserve the form of the variation in concentration of the compositions C1 and C2.
En sortie de filière 15, le fil obtenu, qui est une fibre optique plastique à gradient d'indice, 6, est étiré par un cabestan 10. Selon un mode de réalisation, la fibre optique plastique 6 est durcie par photo-
réticulation à l'aide d'une source 7 de rayons ultra-violets (UV) en une fibre optique plastique polymérisée 9. Puis, au moyen du cabestan 10, la fibre optique plastique 9 est enroulée sur une bobine 11. Le diamètre de la fibre 9 est donné par la filière 15, mais il peut être affiné selon la force de le filage réalisé au moyen du cabestan 10. On peut utiliser indifferement l'une des fibres optiques plastiques 6 ou 9 en tant que produit fini selon l'invention.At the outlet of die 15, the wire obtained, which is a plastic optical fiber with an index gradient, 6, is drawn by a capstan 10. According to one embodiment, the plastic optical fiber 6 is cured by photo- crosslinking using a source 7 of ultraviolet (UV) rays in a polymerized plastic optical fiber 9. Then, by means of the capstan 10, the plastic optical fiber 9 is wound on a reel 11. The diameter of the fiber 9 is given by the die 15, but it can be refined according to the strength of the spinning carried out by means of the capstan 10. One can indifferently use one of the plastic optical fibers 6 or 9 as a finished product according to the invention .
La figure 2 représente une vue schématique du profil d'indice obtenu pour une fibre optique fabriquée par le dispositif de la figure 1. On voit le profil de l'indice de réfraction n de la fibre optique 6 de la figure 1 , pratiquement lissé de façon à former un gradient de forme parabolique, en fonction de la distance r au centre de la fibre 6, qui est sur l'axe X.2 shows a schematic view of the index profile obtained for an optical fiber manufactured by the device of Figure 1. We see the profile of the refractive index n of the optical fiber 6 of Figure 1, practically smoothed so as to form a gradient of parabolic shape, as a function of the distance r from the center of the fiber 6, which is on the axis X.
La fibre ainsi obtenue est donc une fibre à gradient d'indice, mais le procédé ci-dessus peut également permettre d'obtenir une fibre à saut d'indice. Dans ce cas, on ne procède pas au mélange actif des compositions C1 et C2. C1 et C2 sont alors introduites dans un pot répartiteur prolongé d'une filière, où le dimamètre final de la fibre et la proportion de cœur et de gaine sont gouvernés par la pression et la température des compositions C1 et C2 ainsi que par le diamètre de la filière. La présente invention concerne également d'autres types de procédés pour obtenir des fibres optiques plastiques.The fiber thus obtained is therefore a gradient index fiber, but the above method can also make it possible to obtain a index-jump fiber. In this case, the active mixture of compositions C1 and C2 is not carried out. C1 and C2 are then introduced into a distributor pot extended by a die, where the final fiber dimameter and the proportion of core and cladding are governed by the pressure and the temperature of the compositions C1 and C2 as well as by the diameter of the sector. The present invention also relates to other types of methods for obtaining plastic optical fibers.
Ainsi, pour fabriquer une fibre optique plastique à gradient d'indice, on peut utiliser un procédé tel que celui décrit dans le document US-6 071 441 , dit procédé préforme. Selon un exemple de mise en œuvre, pour la fabrication de la préforme, 100 g de polymère P du type copolymère CTFE /VCA dont la proportion molaire en motif CTFE varie entre 30 et 70% de masse molaire moyenne de 5.105 environ sont fondus à une température comprise entre 200 et 250 °C dans un tube cylindrique en verre, sans le remplir entièrement de sorte qu'un espace vacant est ménagé dans le tube contenant le polymère P avant de sceller celui-ci sous vide. Le tube en
verre est alors placé en position horizontale dans un four. Il est ensuite soumis à un mouvement de rotation autour de son axe horizontal (dont la vitesse est fixée à 2 000 tours/minute), et le four est porté à une température telle que la viscosité du polymère P fondu est comprise entre 103 et 105 poise, pendant trois heures. Le tube est ensuite refroidi progressivement pendant une heure. Le corps tubulaire ainsi obtenu a un diamètre extérieur de 17 mm et un diamètre intérieur de 5 mm, et son indice de réfraction est de 1 ,45.Thus, to manufacture a plastic optical fiber with an index gradient, it is possible to use a method such as that described in document US Pat. No. 6,071,441, known as the preform method. According to an example of implementation, for the manufacture of the preform, 100 g of polymer P of the CTFE / VCA copolymer type, the molar proportion of CTFE motif varies between 30 and 70% of average molar mass of approximately 5.10 5 are melted at a temperature between 200 and 250 ° C in a cylindrical glass tube, without completely filling it so that a vacant space is made in the tube containing the polymer P before sealing it under vacuum. The tube in glass is then placed in a horizontal position in an oven. It is then subjected to a rotational movement around its horizontal axis (the speed of which is fixed at 2000 revolutions / minute), and the oven is brought to a temperature such that the viscosity of the molten polymer P is between 10 3 and 10 5 poise, for three hours. The tube is then gradually cooled for one hour. The tubular body thus obtained has an outside diameter of 17 mm and an inside diameter of 5 mm, and its refractive index is 1.45.
Un dopant D est alors introduit dans la partie centrale de ce corps tubulaire, toujours dans le tube de verre. Sa proportion est de 4% en poids par rapport au polymère P. Pour que le dopant soit adapté au matériau utilisé, il est préférable qu'il remplisse les deux conditions suivantes:A dopant D is then introduced into the central part of this tubular body, still in the glass tube. Its proportion is 4% by weight relative to the polymer P. For the dopant to be suitable for the material used, it is preferable that it meets the following two conditions:
• son indice de réfraction n est supérieur à celui du polymère P• its refractive index n is higher than that of the polymer P
• la différence des paramètres de solubilité du polymère P et du dopant D, | δp-δp I est inférieure ou égale à 7 (cal/cm3)1 /2.• the difference in the solubility parameters of the polymer P and of the dopant D, | δp-δp I is less than or equal to 7 (cal / cm 3 ) 1/2 .
Le Tableau 3 suivant rassemble quelques exemples de composés pouvant être en mesure d'être utilisés en tant que dopant D pour cette application.The following Table 3 brings together some examples of compounds which may be able to be used as dopant D for this application.
TABLEAU 3TABLE 3
L'ensemble est de nouveau mis en rotation dans un four. Le dopant D diffuse thermiquement à travers le polymère P fondu pendant 6 heures. Le four est enfin progressivement refroidi à une vitesse de 15°C/heure jusqu'à température ambiante. Un corps tubulaire de 17 mm de diamètre extérieur et de 4,5 mm de diamètre intérieur est obtenu avec un profil à gradient d'indice de réfraction. The assembly is again rotated in an oven. The dopant D thermally diffuses through the molten polymer P for 6 hours. The oven is finally gradually cooled at a speed of 15 ° C / hour to room temperature. A tubular body 17 mm in outside diameter and 4.5 mm in inside diameter is obtained with a gradient index of refraction profile.
Ce corps tubulaire, constituant la préforme de la fibre optique plastique à gradient d'indice, est placé dans un four d'étirage à une température comprise entre 200 et 250° C. Sa partie supérieure est reliée à une pompe à vide pendant l'étape de filage. De cette façon, la préforme se rétreint et une fibre optique à gradient d'indice de réfraction est récupérée. Ses dimensions dépendent de la vitesse de filage, de préférence comprise entre 5 et 10 m/min et de la température du four.This tubular body, constituting the preform of the plastic optical fiber with an index gradient, is placed in a drawing oven at a temperature between 200 and 250 ° C. Its upper part is connected to a vacuum pump during the spinning step. In this way, the preform shrinks and an optical fiber with a refractive index gradient is recovered. Its dimensions depend on the spinning speed, preferably between 5 and 10 m / min and on the oven temperature.
Avantageusement, l'utilisation de polymères P selon l'invention, ayant une température de transition vitreuse supérieure à celles du PMMA ou du CYTOP, matériaux classiquement utilisés dans le procédé « préforme » connu, conduit à des fibres ayant une transparence supérieure à celles obtenues avec les matériaux classiques. Ceci est illustré en figure 3, où est représentée en fonction de la longueur d'onde en nm, l'atténuation (en dB/km) d'une fibre optique plastique à gradient d'indice obtenue selon le procédé qui vient d'être décrit, à partir de polymère CYTOP de l'art antérieur (courbe 31 ), de polymère PMMA de l'art antérieur (courbe 32) et de polymère (CTFE)0,50 (VCA)0,50 selon l'invention (courbe 33). Pour fabriquer des fibres optiques plastiques à saut d'indice selon l'invention, on peut procéder par exemple par filage d'un polymère P selon l'invention, par exemple obtenu selon l'un des exemples ci-dessus, à l'état fondu, et dépôt simultané d'une résine photoréticulable d'indice de réfraction inférieur à celui du polymère P, cette résine étant ensuite photopolymérisée. L'épaisseur de la couche de résine ainsi déposée est par exemple de l'ordre de 100 μm.
On peut de manière alternative, pour fabriquer une fibre optique plastique à saut d'indice selon l'invention, procéder par coextrusion du polymère P avec un polymère d'indice de réfraction inférieur à celui du polymère P, comme par exemple le PVDF, le Teflon ® AF de du Pont de Nemours ou encore le Hyflon AD ® de la société AUSIMONT.Advantageously, the use of polymers P according to the invention, having a glass transition temperature higher than those of PMMA or of CYTOP, materials conventionally used in the known “preform” process, leads to fibers having a transparency greater than those obtained. with classic materials. This is illustrated in FIG. 3, where is represented as a function of the wavelength in nm, the attenuation (in dB / km) of a plastic optical fiber with an index gradient obtained according to the process which has just been describes, from CYTOP polymer of the prior art (curve 31), PMMA polymer of the prior art (curve 32) and polymer (CTFE) 0.50 (VCA) 0.50 according to the invention (curve 33). To manufacture plastic optical fibers with index jump according to the invention, it is possible for example to spin a polymer P according to the invention, for example obtained according to one of the examples above, in the state molten, and simultaneous deposition of a photocrosslinkable resin with a refractive index lower than that of the polymer P, this resin then being photopolymerized. The thickness of the resin layer thus deposited is for example of the order of 100 μm. One can alternatively, to manufacture a plastic optical fiber with index jump according to the invention, proceed by coextrusion of the polymer P with a polymer of refractive index lower than that of the polymer P, such as for example PVDF, Teflon ® AF by du Pont de Nemours or the Hyflon AD ® by AUSIMONT.
Les deux derniers procédés mentionnés sont en tant que tels bien connus de l'homme de l'art et ne seront pas décrits plus en détail ici.The last two methods mentioned are as such well known to those skilled in the art and will not be described in more detail here.
Bien entendu, les procédés selon l'invention ne sont pas limités aux modes de réalisation qui viennent d'être décrits. Ainsi, on pourra utiliser comme dispositif pour mettre en œuvre le procédé UV pour la fabrication de fibres optiques à gradient d'indice tout dispositif adapté pour effectuer le mélange actif, et notamment, mais non exclusivement, ceux décrits dans le document EP-1 067222.Of course, the methods according to the invention are not limited to the embodiments which have just been described. Thus, it is possible to use as a device for implementing the UV method for the manufacture of optical fibers with an index gradient any device suitable for carrying out the active mixing, and in particular, but not exclusively, those described in document EP-1 067222. .
En outre, les compositions et exemples donnés ne le sont qu'à titre indicatif, et l'on pourra les modifier sans sortir du cadre de l'invention du moment que le copolymère P conserve les caractéristiques générales mentionnées plus haut.In addition, the compositions and examples given are for information only, and they can be modified without departing from the scope of the invention as long as the copolymer P retains the general characteristics mentioned above.
Enfin, on pourra remplacer tout moyen par un moyen équivalent sans sortir du cadre de l'invention.
Finally, any means can be replaced by equivalent means without departing from the scope of the invention.
Claims
1. Procédé de fabrication d'une fibre optique plastique à partir d'au moins un polymère P, ledit procédé étant caractérisé en ce que ledit polymère P est un copolymère comprenant au moins deux unités répétitives P1 et P2 de formules générales suivantes, i et j correspondant à un nombre répétitif d'unités :1. Method for manufacturing a plastic optical fiber from at least one polymer P, said method being characterized in that said polymer P is a copolymer comprising at least two repeating units P1 and P2 of the following general formulas, i and j corresponding to a repetitive number of units:
ledit copolymère P étant transparent, de nature amorphe et ayant une teneur en motif P2 comprise entre sensiblement 30 et 70% molaire pour X=F ou Cl dans P1.said copolymer P being transparent, of amorphous nature and having a content of motif P2 of between substantially 30 and 70 mol% for X = F or Cl in P1.
2. Procédé de fabrication selon la revendication 1 d'une fibre optique plastique à saut d'indice, dont l'indice de réfraction varie de manière discontinue entre le centre et la périphérie de la fibre, ou à gradient d'indice dont l'indice varie continûment entre le centre et la périphérie de la fibre, à partir d'au moins ledit polymère P et d'au moins un diluant réactif D1 permettant de faire varier l'indice de réfraction de réfraction de ladite fibre, ledit procédé étant caractérisé en ce qu'il comprend les étapes suivantes : • préparation de deux compositions d'indice de réfraction différent, la différence d'indice de réfraction entre les deux compositions étant au moins de 5.10"3, comprenant chacune au moins le polymère P, l'une des compositions, dite première composition, comprenant en outre au moins le diluant réactif D1 , un amorceur de polymérisation radicalaire étant présent dans au moins l'une des compositions,2. The manufacturing method according to claim 1 of a plastic optical fiber with index jump, whose refractive index varies discontinuously between the center and the periphery of the fiber, or with index gradient whose index varies continuously between the center and the periphery of the fiber, starting from at least said polymer P and from at least one reactive diluent D1 making it possible to vary the refractive index of refraction of said fiber, said method being characterized in that it comprises the following stages: • preparation of two compositions of different refractive index, the difference in refractive index between the two compositions being at least 5.10 "3 , each comprising at least the polymer P, l one of the compositions, called the first composition, further comprising at least the reactive diluent D1, an initiator of radical polymerization being present in at least one of the compositions,
• filage• spinning
• réticulation du diluant réactif conduisant à une fibre optique plastique.• crosslinking of the reactive diluent leading to a plastic optical fiber.
3. Procédé selon la revendication 2 caractérisé en ce que, lorsque la fibre optique plastique est une fibre à gradient d'indice, ledit procédé comprend en outre, après l'étape de préparation desdites compositions, une étape de mélange actif des deux compositions afin d'obtenir la variation continue de l'indice de réfraction de la fibre optique, suivi du filage dudit mélange.3. Method according to claim 2 characterized in that, when the plastic optical fiber is a gradient index fiber, said method further comprises, after the step of preparing said compositions, a step of active mixing of the two compositions in order to obtain the continuous variation of the refractive index of the optical fiber, followed by the spinning of said mixture.
4. Procédé selon l'une des revendications 2 ou 3 caractérisé en ce que ladite réticulation est une photo-réticulation et en ce que ledit amorceur est un photo-amorceur. 4. Method according to one of claims 2 or 3 characterized in that said crosslinking is a photo-crosslinking and in that said initiator is a photoinitiator.
5. Procédé selon l'une des revendications 2 à 4 caractérisé en ce que la masse molaire du polymère P est comprise entre 1 000 et 20000 g. moles"1 et le diluant réactif D1 a une masse molaire comprise entre 100 et 1 000 g. moles"1.5. Method according to one of claims 2 to 4 characterized in that the molar mass of the polymer P is between 1,000 and 20,000 g. moles "1 and the reactive diluent D1 has a molar mass of between 100 and 1000 g. moles " 1 .
6. Procédé selon l'une des revendications 2 à 5 caractérisé en ce que le diluant réactif D1 comprend au moins un groupement insaturé réactif vis-à-vis des UV choisi dans le groupe formé par les groupements vinyliques et les groupements acryliques.6. Method according to one of claims 2 to 5 characterized in that the reactive diluent D1 comprises at least one reactive unsaturated group vis-à-vis UV chosen from the group formed by vinyl groups and acrylic groups.
7. Procédé selon l'une des revendications 2 à 6 caractérisé en ce que la température de transition vitreuse dudit copolymère est comprise entre 60°C et 160°C.7. Method according to one of claims 2 to 6 characterized in that the glass transition temperature of said copolymer is between 60 ° C and 160 ° C.
8. Procédé selon l'une des revendications 2 à 7 caractérisé en ce que la masse molaire dudit copolymère est comprise entre 500 et 106 g. moles"1.8. Method according to one of claims 2 to 7 characterized in that the molar mass of said copolymer is between 500 and 10 6 g. moles "1 .
9. Procédé selon l'une des revendications 2 à 8 caractérisé en ce que la cinétique de réticulation est telle que, sous insolation maximale et transformation complète dudit amorceur, le temps de gel est inférieur à 10 s. 9. Method according to one of claims 2 to 8 characterized in that the crosslinking kinetics is such that, under maximum insolation and complete transformation of said initiator, the gel time is less than 10 s.
10. Procédé selon la revendication 9 caractérisé en ce que le temps de gel est inférieur à 2 s. 10. Method according to claim 9 characterized in that the gel time is less than 2 s.
11. Procédé selon l'une des revendications 2 à 10 caractérisé en ce que la seconde desdites compositions comprend au moins un diluant réactif D2 permettant lui aussi de faire varier l'indice de réfraction, le diluant réactif D2 étant d'indice de réfraction sensiblement différent de l'indice de réfraction de D1, ayant une masse molaire comprise entre 100 et 1 000 g. moles"1, et comprenant au moins un groupement insaturé réactif vis-à-vis des UV choisi dans le groupe formé par les groupements vinyliques et les groupements acryliques.11. Method according to one of claims 2 to 10 characterized in that the second of said compositions comprises at least one reactive diluent D2 also allowing to vary the refractive index, the reactive diluent D2 being of refractive index substantially different from the refractive index of D1, having a molar mass of between 100 and 1000 g. moles "1 , and comprising at least one UV-reactive unsaturated group chosen from the group formed by vinyl groups and acrylic groups.
12. Procédé selon la revendication 11 caractérisé en ce que les diluants réactifs D1 et D2 sont de viscosité pratiquement identiques et tel que la proportion en masse dudit polymère P par rapport aux constituants de la composition est pratiquement constante pour chacune desdites compositions.12. Method according to claim 11 characterized in that the reactive diluents D1 and D2 are of practically identical viscosity and such that the proportion by mass of said polymer P relative to the constituents of the composition is practically constant for each of said compositions.
13. Procédé selon l'une des revendications 3 à 12 caractérisé en ce que le mélange des deux compositions est réalisé à une température telle que la viscosité à 20° C de chacune des deux compositions est comprise entre 1 et 25 Pa.s.13. Method according to one of claims 3 to 12 characterized in that the mixing of the two compositions is carried out at a temperature such that the viscosity at 20 ° C of each of the two compositions is between 1 and 25 Pa.s.
14. Procédé selon l'une des revendications 2 à 13 caractérisé en ce que le filage est réalisé à une température telle que la viscosité de chacune des deux compositions est supérieure à 500 mPa.s. 14. Method according to one of claims 2 to 13 characterized in that the spinning is carried out at a temperature such that the viscosity of each of the two compositions is greater than 500 mPa.s.
15. Procédé selon l'une des revendications 2 à 14 caractérisé en ce que tout composant d'une desdites compositions est un matériau au moins partiellement halogène.15. Method according to one of claims 2 to 14 characterized in that any component of one of said compositions is an at least partially halogenated material.
16. Procédé selon la revendication 15 caractérisé en ce que dans le cas de la présence de diluant réactif D2 dans la seconde desdites compositions, l'un des deux diluants réactifs D1 ou D2 est au moins partiellement fluoré et l'autre des deux diluants réactifs D2 ou D1 est au moins partiellement chloré ou chloro-fluoré.16. The method of claim 15 characterized in that in the case of the presence of reactive diluent D2 in the second of said compositions, one of the two reactive diluents D1 or D2 is at least partially fluorinated and the other of the two reactive diluents D2 or D1 is at least partially chlorinated or chloro-fluorinated.
17. Procédé de fabrication selon la revendication 1 d'une fibre optique plastique à gradient d'indice dont l'indice varie continûment entre le centre et la périphérie de la fibre, à partir d'au moins ledit polymère17. The manufacturing method according to claim 1 of a plastic optical fiber with an index gradient whose index varies continuously between the center and the periphery of the fiber, from at least said polymer.
P et d'au moins un dopant D permettant de faire varier l'indice de réfraction de ladite fibre, l'indice de réfraction dudit dopant D étant supérieur à celui dudit polymère P, ledit procédé étant caractérisé en ce qu'il comprend les étapes suivantes : • fusion du polymère P dans un tubeP and at least one dopant D making it possible to vary the refractive index of said fiber, the refractive index of said dopant D being greater than that of said polymer P, said method being characterized in that it comprises the steps following: • melting of polymer P in a tube
• mise en rotation dudit tube autour de son axe• rotation of said tube around its axis
• refroidissement dudit tube de manière à former à l'intérieur dudit tube un corps tubulaire en polymère P• cooling of said tube so as to form inside said tube a tubular body of polymer P
• introduction dudit dopant D dans ledit corps tubulaire formé par le polymère PIntroduction of said dopant D into said tubular body formed by the polymer P
• chauffage et mise en rotation dudit tube autour de son axe de manière à faire diffuser thermiquement ledit dopant D à travers ledit polymère P et à former un corps tubulaire de polymère P dopé • refroidissement pour obtenir une préforme tubulaire• heating and rotation of said tube around its axis so as to thermally diffuse said dopant D through said polymer P and to form a tubular body of doped polymer P • cooling to obtain a tubular preform
• étirage de ladite préforme tubulaire reliée à une pompe à vide pour former une fibre optique plastique.• stretching of said tubular preform connected to a vacuum pump to form a plastic optical fiber.
18. Procédé de fabrication selon la revendication 1 d'une fibre optique plastique à saut d'indice dont l'indice varie de manière discontinue entre le centre et la périphérie de la fibre, à partir d'au moins ledit polymère P, ledit polymère P étant filé à l'état fondu et simultanément revêtu d'une résine photoréticulable d'indice de réfraction inférieur à celui du polymère P, qui est ensuite photopolyméπ'sée. 18. The manufacturing method according to claim 1 of a plastic optical fiber with index jump whose index varies discontinuously between the center and the periphery of the fiber, from at least said polymer P, said polymer P being spun in the molten state and simultaneously coated with a photocrosslinkable resin with a refractive index lower than that of the polymer P, which is then photopolyméπ ' sée.
19. Procédé de fabrication selon la revendication 1 d'une fibre optique plastique à saut d'indice dont l'indice varie de manière discontinue entre le centre et la périphérie de la fibre, à partir d'au moins ledit polymère P, par coextrusion dudit polymère P avec un autre polymère d'indice de réfraction inférieur à celui dudit polymère P.19. The manufacturing method according to claim 1 of a plastic optical fiber with index jump whose index varies discontinuously. between the center and the periphery of the fiber, from at least said polymer P, by coextrusion of said polymer P with another polymer of refractive index lower than that of said polymer P.
20. Fibre optique plastique à saut d'indice ou à gradient d'indice caractérisée en ce qu'elle est obtenue par le procédé selon l'une des revendications 1 à 19.20. Plastic optical fiber with index jump or index gradient characterized in that it is obtained by the method according to one of claims 1 to 19.
21. Guide d'ondes optique caractérisé en ce qu'il est obtenu par le procédé selon l'une des revendications 1 à 20. 21. Optical waveguide characterized in that it is obtained by the method according to one of claims 1 to 20.
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FR0115038 | 2001-11-19 | ||
FR0115038A FR2832514B1 (en) | 2001-11-19 | 2001-11-19 | METHOD FOR MANUFACTURING AN INDEX GRADIENT PLASTIC OPTICAL FIBER AND INDEX GRADIENT OPTICAL FIBER OBTAINED BY THIS PROCESS |
PCT/FR2002/003932 WO2003043805A2 (en) | 2001-11-19 | 2002-11-18 | Method for making a plastic optical fiber, and resulting plastic optical fiber |
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US (1) | US20050062180A1 (en) |
EP (1) | EP1451005A2 (en) |
JP (1) | JP2005509912A (en) |
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US20050157999A1 (en) * | 2002-12-27 | 2005-07-21 | Zhen Zhen | Graded index polymer optical fiber and a method of making the same |
CN109540847B (en) * | 2018-12-13 | 2021-10-19 | 山东师范大学 | graphene/gold/D type plastic optical fiber SPR sensor and preparation method thereof |
WO2024011245A2 (en) * | 2022-07-08 | 2024-01-11 | Samtec, Inc. | Additive manufactured waveguide |
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US4138194A (en) * | 1977-10-14 | 1979-02-06 | E. I. Du Pont De Nemours And Company | Low attenuation optical fiber of deuterated polymer |
JP2762417B2 (en) * | 1988-04-15 | 1998-06-04 | 三菱レイヨン株式会社 | Manufacturing method of optical transmission body |
JP2762416B2 (en) * | 1988-04-15 | 1998-06-04 | 三菱レイヨン株式会社 | Manufacturing method of optical transmission body |
US5760139A (en) * | 1994-04-18 | 1998-06-02 | Yasuhiro Koike | Graded-refractive-index optical plastic material and method for its production |
ES2191050T3 (en) * | 1994-04-18 | 2003-09-01 | Yasuhiro Koike | RESIN OF OPTICAL USE OF THE TYPE OF DISTRIBUTION OF REFRACTION INDEX AND THE PROCEDURE OF PRODUCTION OF THIS RESIN. |
US5670590A (en) * | 1994-05-06 | 1997-09-23 | Minnesota Mining And Manufacturing Company | Energy polymerizable compositions, homopolymers and copolymers of oxazolines |
JP3951404B2 (en) * | 1998-01-26 | 2007-08-01 | 旭硝子株式会社 | Electric double layer capacitor |
FR2784196B1 (en) * | 1998-10-01 | 2000-12-15 | Cit Alcatel | INDEX GRADIENT PLASTIC OPTICAL FIBER AND CONTINUOUSLY MANUFACTURING INDEX GRADIENT PLASTIC OPTICAL FIBER |
FR2795997B1 (en) * | 1999-07-05 | 2001-10-19 | Cit Alcatel | METHOD FOR MANUFACTURING AN INDEX GRADIENT PLASTIC OPTICAL FIBER |
FR2832515B1 (en) * | 2001-11-19 | 2004-01-30 | Nexans | METHOD FOR MANUFACTURING AN INDEX GRADIENT PLASTIC OPTICAL FIBER AND INDEX GRADIENT OPTICAL FIBER OBTAINED BY THIS PROCESS |
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2001
- 2001-11-19 FR FR0115038A patent/FR2832514B1/en not_active Expired - Fee Related
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2002
- 2002-11-18 EP EP02803435A patent/EP1451005A2/en not_active Withdrawn
- 2002-11-18 JP JP2003545464A patent/JP2005509912A/en not_active Withdrawn
- 2002-11-18 WO PCT/FR2002/003932 patent/WO2003043805A2/en not_active Application Discontinuation
- 2002-11-18 CN CNA028257782A patent/CN1606494A/en active Pending
- 2002-11-18 KR KR10-2004-7007348A patent/KR20040066812A/en not_active Application Discontinuation
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