WO2002046811A1 - Plastic optical fiber - Google Patents

Abstract

A step index type plastic optical fiber large in numerical aperture (NA), low in transmission loss over a wide wavelength range, and small in bending loss, wherein the materials of a core and a clad consist of amorphous fluororesin having substantially no hydrogen atom, and the core material uses amorphous fluororesin having higher refractive index than ever before, and /or the clad material uses amorphous fluororesin having lower refractive index than before, thereby increasing the difference in refractive index between the both materials.

Description

Technical field

 The present invention relates to a step index type plastic optical fiber (hereinafter referred to as an SI type optical fiber), and more particularly to an SI type optical fiber capable of transmitting a wide range of light from the visible to the near-infrared region and having a large numerical aperture. .

 Light

 Rice field

w:

 Conventional optical fibers are mainly made of quartz, but plastic optical fibers have been developed and put into practical use to overcome poor workability and weakness against bending. An ordinary plastic optical fiber has a basic structural unit consisting of a core made of a transparent resin such as methyl methyl acrylate and polycarbonate, and a clad made of a resin such as a fluoropolymer that has a smaller refractive index and is transparent. .

 However, these resin materials have overtone absorption of stretching vibration based on carbon-hydrogen bonds existing in the polymer, and have large transmission loss in the near infrared region. To solve this problem, studies are being made to reduce transmission loss in the near-infrared region by introducing a fluorine atom instead of a hydrogen atom to eliminate carbon-hydrogen bonds. For example, Japanese Patent Publication No. 28221935 discloses an SI type optical fiber using a perfluoropolymer for the core and cladding materials.

 The conventional plastic optical fiber using perfluoropolymer for the core and cladding has a problem that the numerical aperture (NA) is small because the refractive index difference between the core and the cladding is small. The present invention solves this problem, and provides a plastic optical fiber suitable for use in optical communication media such as various sensors for industrial use and medical use, which has a small loss during bending and can receive light in a wide range. With the goal. Disclosure of the invention

The present invention provides an amorphous fluororesin (A-1) in which a core is substantially composed of a fluoropolymer having substantially no hydrogen atom and having a chlorine atom in a side chain; An SI type light, comprising an amorphous fluororesin (B) composed of a fluorine-containing polymer having substantially no hydrogen atoms, wherein the refractive index difference between the core and the clad is 0.020 or more. Fiber.

 Further, in the present invention, the core is made of an amorphous fluororesin (A) composed of a fluoropolymer containing a high refractive index agent and having substantially no hydrogen atoms, and the cladding is substantially made of hydrogen. An SI type optical fiber, comprising an amorphous fluororesin (B) composed of a fluorine-containing polymer having no atoms and having a refractive index difference of 0.020 or more between the core and the clad. is there.

 Further, the present invention provides an amorphous fluororesin (A) whose core is composed of a fluoropolymer having substantially no hydrogen atoms, or an amorphous fluororesin (A) containing a high refractive index agent. The cladding is made of an amorphous fluororesin (B-2) composed of a fluorine-containing polymer having a refractive index of less than 1.300, which has substantially no hydrogen atoms, and the refractive index difference between the core and the cladding is 0. 020 or more, characterized in that it is not less than 020.

 Further, the present invention provides an amorphous fluororesin (A) in which the core is composed of a fluorine-containing polymer represented by the following formula (1) and having a repeating unit in which the monomer (a) is cyclopolymerized. Is composed of the amorphous fluororesin (A) containing a high refractive index agent, and the cladding is made of a fluoropolymer having a repeating unit obtained by polymerizing a monomer (b-1) represented by the following formula (4). Composed of an amorphous fluororesin (B-3) or an amorphous fluororesin (B-3) containing a fluorinated plasticizer having substantially no hydrogen atoms, and the refractive index of the core and the clad. An SI type optical fiber, characterized in that the difference is 0.020 or more.

However, m is an integer of 0 to 5, R ¹ R ² , R ³ and R ⁴ are each independently a perfluoroalkyl group having 1 to 9 carbon atoms, a chlorine atom or a fluorine atom, and R ¹³ is 2 to 5 carbon atoms. 9 pel full O b alkyl group, R ¹⁴ represents a Perufuruoroaru kill group or a fluorine atom of one to 9 carbon atoms.

CF _? = CF—0— CR ^ R ² — (CR ³ R ⁴ ) _m -CF = CF ₂ (1)

 Further, the present invention provides an amorphous fluororesin (A) whose core is composed of a fluoropolymer having substantially no hydrogen atoms, or an amorphous fluororesin (A) containing a high refractive index agent. An amorphous fluororesin (B) in which the clad is composed of a fluorine-containing polymer having substantially no hydrogen atoms, or an amorphous fluororesin containing a fluorine-containing plasticizer having substantially no hydrogen atoms ( B) and having a numerical aperture (NA) of 0.415 or more.

 The present invention also provides an optical member characterized by using perfluoro (2-pentyl-1,3-dioxole), a fluorine-containing polymer having a repeating unit obtained by polymerizing perfluoro (2-pentyl-1,3-dioxole), and the polymer. is there. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph showing the transmission loss (wavelength 500 000 nm) of the SI optical fiber of Example 43. BEST MODE FOR CARRYING OUT THE INVENTION

 The amorphous fluororesin in the present invention is composed of only one kind or a mixed two or more kinds of specific fluoropolymers which become amorphous, and the fluoropolymers as other constituents. In addition, a small amount of additives may be contained. Further, the amorphous fluororesin may contain a small amount of a crystalline fluoropolymer (a fluoropolymer which becomes crystalline by itself) as long as it is entirely amorphous.

Certain fluoropolymers are also polymers having substantially no hydrogen atoms. When a polymer other than the specific fluorine-containing polymer that becomes amorphous is used in combination, the other polymer is a polymer having substantially no hydrogen atom. That is, the polymer constituting the amorphous fluororesin in the present invention is composed of a polymer having substantially no hydrogen atoms. Is done. Hereinafter, unless otherwise specified, the polymer constituting the amorphous fluororesin means a polymer having substantially no hydrogen atom. In the following, the term “polymer” refers particularly to

Unless referred to as “homopolymer” or “copolymer”, it may be a homopolymer or a copolymer.

 SI type optical fibers consist of a core and a cladding having a relatively lower refractive index. The larger the refractive index difference between the core and the clad, the larger the numerical aperture (NA). Amorphous fluoroplastics are inherently low-refractive-index resins, and when they are used as the core material, the cladding material that must have a lower refractive index than that of the resin has a smaller range of choices. It was difficult to increase the difference. The present invention uses an amorphous fluororesin in the same category as the core as the material of the clad, increases the refractive index difference between the core and the clad as compared with the conventional one, and improves the optical properties and the physical properties of each material. The purpose is to enhance mechanical properties.

 One aspect of the present invention is to increase the refractive index of the core by using an amorphous fluororesin composed of a fluorine-containing polymer having a chlorine atom, which has the effect of increasing the refractive index, as a material of the core. This is to increase the difference in the refractive index between them. This chlorine atom must be a chlorine atom bonded to the side chain of the polymer, and if the chlorine atom is bonded to a carbon atom of the main chain, the polymerizability of the monomer deteriorates and the polymer becomes stable. There are problems such as the inability to obtain a high molecular weight polymer having physical properties, or the increase in crystallinity and the increase in scattering loss. In the present invention, the main chain of the fluorinated polymer constituting the amorphous fluororesin is composed of a chain of only carbon atoms, and the main chain is composed of two carbon atoms constituting a polymerizable double bond. Formed from a chain. Further, in a polymer obtained by cyclopolymerization of a monomer having two polymerizable double bonds (hereinafter also referred to as fluorine-containing gens), four carbon atoms constituting two polymerizable double bonds are used. The main chain is formed from the chain of Therefore, having a chlorine atom in the side chain means having a chlorine atom directly bonded to another carbon atom without having a chlorine atom directly bonded to a carbon atom constituting these polymerizable double bonds. Means

The present invention is also to increase the refractive index of the core by using an amorphous fluororesin containing a high refractive index agent as the material of the core, thereby increasing the refractive index difference from the cladding. This high refractive index agent is a fluorine-containing polymer that constitutes the compounded amorphous fluorine resin. It is a compound having a higher refractive index than the body, and the refractive index of the amorphous fluororesin containing it is higher than that of the amorphous fluororesin not containing it. Usually, the refractive index of the amorphous fluororesin increases with the amount of the high refractive index agent.特 に As the refractive index-imparting agent, a fluorine-containing aromatic compound having substantially no hydrogen atom is particularly preferable. Further, in the present invention, the refractive index difference from the core is increased by using a fluorine-containing polymer having a lower refractive index than the conventional one as the fluorine-containing polymer constituting the cladding amorphous fluorine resin. Perfluoro (2,2-dimethyl-1,3-dioxol) (formula (5) below, hereinafter referred to as PDD) polymer is known as a fluorine-containing polymer constituting the amorphous fluorine resin of the clad. However, in the present invention, a fluoropolymer having a lower refractive index is used.

 These means for increasing the refractive index difference between the core and the clad can be used in combination of two or more. For example, a core comprising a combination of a fluorine-containing polymer having a chlorine atom and a high-refractive index agent, and a combination of this core and a clad comprising a fluoropolymer having a lower refractive index, And a combination of a core made of an amorphous fluororesin and a clad made of a fluoropolymer having a lower refractive index. Further, in the present invention, the clad can be made of an amorphous fluororesin containing a fluorine-containing plasticizer. The fluoropolymer having a low refractive index, which is a material of the clad, usually has high rigidity and is brittle, so it is preferable to increase the flexibility by blending a plasticizer. By forming the clad with a highly flexible material, it is possible to suppress the occurrence of cracks and the like when the SI type optical fiber is bent. The plasticizer must be a fluorine compound in order to enhance the affinity with the fluoropolymer, and preferably has substantially no hydrogen atom. When the fluorine-containing plasticizer is a compound having a high fluorine content, it also has the effect of lowering the refractive index of the clad.

In the present invention, increasing the refractive index difference between the core and the clad, that is, the numerical aperture Increasing the (NA) suppresses the increase in transmission loss when the SI-type optical fiber is bent, and when used in a sensor, it can collect light from a wide range, improving sensor sensitivity. I like it.

 In order for the SI optical fiber of the present invention to achieve a sufficiently large numerical aperture, the refractive index difference between the amorphous fluorine-containing resin of the core and the amorphous fluorine-containing resin of the clad must be 0.020 or more. is necessary. The larger the refractive index difference, the higher the numerical aperture. The difference in refractive index is preferably at least 0.030, more preferably at least 0.040, further preferably at least 0.045, particularly preferably at least 0.050. And most preferably 0.060 or more. The upper limit of the refractive index difference is not particularly limited, but is usually 0.2.

 Based on this refractive index difference, the numerical aperture of the SI optical fiber of the present invention is preferably 0.280 or more. It is more preferably at least 0.325, further preferably at least 0.364, particularly preferably at least 0.380, most preferably at least 0.415. Although there is no particular upper limit for the numerical aperture, it is usually 0.75.

 In order to increase the refractive index difference, a method using a core material having a higher refractive index as compared with the conventional method, a method using a clad material having a lower refractive index as compared with the conventional method, There is a method of combining a core material having a higher refractive index with a clad material having a lower refractive index as compared with the conventional one. In the present invention, the amorphous fluororesin of the core and the amorphous fluororesin of the clad are used in these methods. It can be applied to any of

 The amorphous fluororesin of the core and the amorphous fluororesin of the clad in the present invention are amorphous fluororesins in the same category except that the refractive index is different. In order to distinguish between the two, the amorphous fluororesin of the core is hereinafter referred to as amorphous fluororesin (A), and the amorphous fluorine resin of the clad is referred to as amorphous fluorine resin jS (B).

The fluorinated polymer constituting these amorphous fluororesins is a polymer having substantially no hydrogen atom and having no carbon-hydrogen bond. Since the amorphous fluororesin is composed of a fluorine-containing polymer having substantially no hydrogen atoms, transmission loss in the near-infrared region is reduced, and light from visible light to near-infrared light is favorably transmitted. An SI optical fiber that can be transmitted is obtained. The fact that the fluororesin is amorphous reduces the scattering loss of the SI optical fiber, particularly in the short wavelength region. Further, the amorphous fluororesin may be composed only of a fluoropolymer, and may contain an additive as long as the optical transmission performance, the mechanical performance and the like are not substantially impaired. Examples of the additives include a plasticizer, a refractive index adjuster, various stabilizers, and a crosslinking agent. These are preferably fluorine compounds having a high affinity for the fluoropolymer in order not to substantially impair the optical transmission performance or to improve the performance. In particular, it is preferable to include a high refractive index agent as a refractive index adjusting agent in the amorphous fluororesin (A) of the core in order to increase the NA of the SI optical fiber. It is preferable to include a plasticizer in the amorphous fluorine resin (B) of the clad in order to impart flexibility to the optical fiber.

 Examples of the fluorine-containing polymer constituting the amorphous fluororesin in the present invention include a polymer having a repeating unit obtained by cyclopolymerization of a fluorine-containing compound (hereinafter, also referred to as a “cyclized polymer”) and a fluorine-containing dioxole A polymer having a repeating unit obtained by polymerizing (hereinafter also referred to as a dioxo-based polymer) is preferable. The cyclized polymer may be a copolymer of two or more fluorogens, or may be a copolymer of a fluorogen and another copolymerizable monomer. Polymerizable monomers are suitable as other copolymerizable monomers. The dioxol-based polymer may also be a copolymer of two or more fluorine-containing dioxols, or may be a copolymer of a fluorine-containing dioxole and another copolymerizable monomer. Further, the fluoropolymer constituting the amorphous fluororesin may be a copolymer of a fluorogen and a dioxole.

 Among the above fluorinated polymers, dioxol-based polymers tend to have a particularly low refractive index as compared with the cyclized polymer, so that the fluorinated polymer constituting the cladding amorphous fluororesin (B) is used. A dioxol-based polymer is preferable as the coalescence, and a cyclized polymer is preferable as the fluorine-containing polymer constituting the amorphous fluororesin (A) of the core. In the case of a copolymer of fluorinated gens and fluorinated dioxols, the copolymer can be used for both the core and the clad due to the difference in refractive index from other amorphous fluororesins to be combined, but is usually suitable as a material for the clad. It is.

The above-mentioned polymer can be obtained by using any of the known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization using the monomers described below. In the polymerization, a radical generator is usually used as a polymerization initiator. To remove unstable groups at polymer terminals after polymerization Post-treatment such as fluorination of the obtained polymer can also be performed.

The viscosity of the above-mentioned fluoropolymer in the molten state is preferably 1 × 10 ² to 1 × 10 ⁵ Pa · s at a melting temperature of 200 to 300 ° C. If the melt viscosity is too high, melt spinning becomes difficult. Further, if the melt viscosity is too low, it is not practically preferable. That is, it is softened at a high temperature when used as an optical transmission body in electronic devices and automobiles, and the transmission performance as an SI type optical fiber is deteriorated.

The number average molecular weight M _n of the fluorine-containing polymer 1 X 10 ⁴ ~5X 10 ⁶ is rather preferred, more preferably ^{5 X 10 4 ~ 1 X 10} 6. If the molecular weight is too small, the heat resistance may be deteriorated, and if it is too large, the melt viscosity becomes high and molding becomes difficult, which is not preferable.

 Among the fluorinated polymers constituting the amorphous fluorinated resin, the cyclized polymer is a repeating unit obtained by cyclizing and polymerizing a monomer represented by the following formula (1) (hereinafter referred to as monomer (a)). Polymers having a position are preferred.

CF ₂ = CF-0-CR ¹ R ^2- (CR ³ R ⁴ ) _m -CF = CF ₂ (1) where m is an integer of 0 to 5, and RR ² , R ³ and R ⁴ are each independently carbon Represents a perfluoroalkyl group of the numbers 1 to 9, a chlorine atom or a fluorine atom. When m is 2 or more, a plurality of R ³ (same for R ⁴ ) may be different from each other. m is particularly preferably an integer of 0 to 3.

The R \ R ^2, R ³ and R ^4, is preferably also three many a pel full O b alkyl group or a chlorine atom other fluorine atom. In particular, as the monomer (a) having a Perufuruo port alkyl group or a chlorine atom, 1 ^ and 1 ² of the least one is a pel full O b alkyl group or a chlorine atom, in all others fluorine atom Certain compounds are preferred. As the perfluoroalkyl group, a perfluoroalkyl group having 1 to 2 carbon atoms is preferable.

The repeating unit obtained by cyclopolymerization of the monomer (a) usually has a structure represented by the following formula (la) or (lb).

 (l a) (l b)

 Examples of the monomer (a) having no chlorine atom (hereinafter referred to as monomer (a-2)) among the monomers (a) include the following monomers. Methods for synthesizing these monomers are disclosed in JP-A-11-131215, JP-A-4-346957, and the like.

Perfluoro (3-oxa-1,5_hexadiene) (CF ₂ = CF—CF ₂ -0-CF = CF ₂ ), Perfluoro (3-oxa-1,6-hexadiene) (CF ₂ = CF-CF ₂ -CF ₂ -0-CF = CF ₂ ) (hereinafter referred to as BVE), perfluoro (3-oxa-4-methyl-1,6-butadiene) (CF ₂ = CF-

CF ₂ -CF (CF ₃ ) -0-CF = CF ₂ ) (hereinafter referred to as BVE-4M), perfluoro (3_oxa-4,4-dimethyl-1,6_butadiene) (CF ₂ = CF-CF ₂ -C (CF ₃ ) ₂ -0-CF = CF ₂ ), perfluoro (3-oxa-5-methyl-1,6-butadiene) (CF ₂ = CF-CF (CF ₃ ) — CF ₂ -0 -CF = CF _2).

 Examples of the monomer having a chlorine atom (hereinafter referred to as monomer (a-1)) among monomers (a) include the following monomers.

4-Chloro-perfluoro (3-oxa_1,5-hexadiene) (CF ₂ = CF-CC 1 F— 0-CF = CF ₂ ), 4-Chloro-perfluoro (3-oxa) - 1, butadiene to _{6-) (CF 2 CF- CF 2} - CC 1 F- O- CF = CF 2) ( hereinafter referred to BVE- 4CL), 4, 4- dichloro chromatography pel full O b (3-O key Sir 1, butadiene to _{6-) (CF 2 = CF- CF} 2 - CC 1 2 - O- CF = CF 2) ( hereinafter BVE- referred 4DCL), 5- chloro-over per full O b (3 Okisa (1,2,1-butadiene) (CF ₂ = CF-CC l F-CF ₂ -0-CF = CF ₂ Cyclic polymer may be a copolymer of two or more monomers (a) The cyclized polymer may be a copolymer of the monomer (a) and another copolymerizable monomer, that is, a cyclized polymer other than a repeating unit obtained by subjecting the monomer (a) to cyclized polymerization. The copolymerizable monomer may include a repeating unit obtained by polymerizing another copolymerizable monomer.The other copolymerizable monomer is preferably a monoene, and the monoene has substantially no hydrogen atom. When it has a chlorine atom, it is a compound having no chlorine atom directly bonded to a carbon atom constituting a polymerizable double bond.

Specifically, for example, a monomer (c) which is a monomer represented by the following formula (2), a monomer (b) which is a monomer represented by the following formula (4), Perfluoroolefins such as perfluoroethylene (hereinafter referred to as TFE) and perfluoro (alkyl) such as perfluoro (3-ox-111-hexene) (CF ₃ -CF ₂ -CF ₂ -0-CF = CF ₂ ) Vinyl ethers) and perfluoro (methylenedioxolanes) such as perfluoro (2-methylene-4-methyl-1,3-dioxolane) (formula (6), hereinafter referred to as MMD).

 Except for the copolymer with the monomer (b), the proportion of the repeating unit in which the monomer (a) is cyclopolymerized with respect to all the repeating units in the cyclized polymer is suitably from 20 to 100 mol%. , 40 to 100% by mole, and particularly preferably 50 to 100% by mole. If this ratio is too small, it is difficult to obtain a polymer having good optical and mechanical properties. In the case of a copolymer with the monomer (b), the ratio of the repeating unit in which the monomer (a) is cyclopolymerized is not particularly limited.

A monomer represented by the following formula (2) (hereinafter referred to as monomer (c)) is a preferable monomer for producing a cyclized polymer having a chlorine atom in a side chain. This monomer is polymerized Having two chlorine atoms at a position distant from the acidic double bond, the cyclized polymer obtained by copolymerizing this monomer (c) and monomer (a) 'has a high refractive index and It becomes a cyclized polymer with good physical properties.

CF ₂ = CF-O-CR ⁵ R ⁶ — (CR ⁷ R ⁸ ) _n — CFC1-CF ₂ C1 (2) where n is an integer of 0 to ⁵ , and R ⁵ , R ⁶ , R ⁷ and R ⁸ are Each independently represents a perfluoroalkyl group having 1 to 9 carbon atoms, a chlorine atom or a fluorine atom. When n is 2 or more, a plurality of R ⁷ (same for R ⁸ ) may be different from each other. n is preferably an integer of 0 to 3, and R ⁵ , ⁶ , R ⁷ and R ⁸ are preferably all fluorine atoms. Also, if having a pel full O b alkyl group is preferably only one or both of R ⁵ and R ⁶ are all other fluorine atoms per full O b alkyl group. Further, as the perfluoroalkyl group, a perfluoroalkyl group having 1 to 2 carbon atoms is preferable.

Specific examples of the monomer (c), for example, 6, 7-dichloro port - Perufuruoro (3 Okisa - _{1-heptene) (CC l F 2 -CC l} F-CF 2 -CF 2 -0-CF = CF ₂ ) (hereinafter referred to as 2CLBVE). A method for synthesizing the monomer (c) is disclosed in, for example, JP-A-11-131215.

 The dioxo-based polymer is a polymer of one or more fluorine-containing dioxoles or a copolymer of a fluorine-containing dioxole and another copolymerizable monomer. As the fluorinated dioxols, a monomer represented by the following formula (3) (hereinafter referred to as a monomer (b)) is preferable.

However, it represents a Perufuruoroaru kill group or a fluorine atom of R ¹¹ and R ¹² are each independently carbon number 1-9. Preferably, at least one of R ¹¹ and R ¹² is a perfluoroalkyl group. Also, perfluoroalkyl-based charcoal The prime number is more preferably 1 to 6.

 The dioxol-based polymer may be one or more polymers of the monomer (b), but usually a copolymer with another copolymerizable monomer is preferred. That is, the dioxyl-based polymer preferably contains a repeating unit in which another copolymerizable monomer is polymerized in addition to the repeating unit in which the monomer (b) is polymerized. The other copolymerizable monomer is preferably a monoene or a cyclizable polymer, and is preferably a monomer having substantially no hydrogen atom, and preferably having no chlorine atom. Specifically, for example, the monomer (a), perfluoroolefins such as TFE,

(3 Okisa - 1 one _{hexene) (CF 3 _CF 2 - CF} 2 - O- CF = CF 2) ( one ether alkylvinyl E) s Perufuruoro such, there is Perufuruoro (methylcarbamoyl Renjiokisoran) s such as MMD . TFE is particularly preferred as the other monomer. Except for the copolymer with the monomer (a), the proportion of the repeating unit in which the monomer (b) is polymerized to all the repeating units in the dioxole polymer is suitably 20 to 95 mol%. It is preferably from 90 to 90 mol%, particularly preferably from 35 to 85 mol%. If the ratio is too small or too large, it is difficult to obtain a polymer having good optical and mechanical properties.

 In the case of a copolymer of the monomer (a) and the monomer (b), the obtained fluoropolymer is used as a constituent of the amorphous fluororesin (A) or the amorphous fluororesin (B) The copolymerization ratio is selected depending on whether or not the component is used (that is, depending on whether it is used for a fluorine-containing polymer having a high refractive index or a fluorine-containing polymer having a low refractive index). In the case of a high-refractive-index fluoropolymer, the monomer (a) is a polymer having a high ratio of repeating units obtained by cyclopolymerization, and in the case of a low-refractive-index fluoropolymer, the monomer (b) is polymerized. The polymer has a high proportion of repeating units. In the former case, the proportion of the repeating unit in which the monomer (b) is polymerized is preferably more than 0 mol% to 40 mol%, and particularly preferably 1 to 30 mol%. In the latter case, the proportion of the repeating unit in which the monomer (b) is polymerized is preferably from 30 mol% to less than 100 mol%, particularly preferably from 40 mol% to 95 mol%.

Among the dioxole-based polymers, the fluorine-containing polymer having a repeating unit in which a monomer represented by the following formula (4) (hereinafter referred to as monomer (b-1)) is polymerized has a lower refractive index . That is, a polymer having a repeating unit obtained by polymerizing PDD and PD Compared to the same polymer except that monomer (b-1) has a polymerized repeating unit instead of polymerized repeating unit, the latter has a lower refractive index.

Here, R ¹³ represents a perfluoroalkyl group having 2 to 9 carbon atoms, and R ¹⁴ represents a perfluoroalkyl group having 9 or less carbon atoms or a fluorine atom. R ¹³ is preferably pel full O b alkyl group from 2 to 6 carbon, R ¹⁴ is preferably Perufuruoroaru kill group or a fluorine atom of one to 6 carbon.

 Specific examples of the monomer (b-1) include the following.

Perfluoro (2-ethyl_1,3-dioxol) (where k is 1 in the following equation (7)),

Perfluoro (2-propyl-1,3-dioxol) (where k is 2 in the following formula (7)),

Perfluoro (2-pentyl-1,3-dioxol) (where k is 4 in the following equation (7)),

Perfluoro (2-ethyl-2-methyl-1,3-dioxole) (where j is 1 in the following formula (8)),

Perfluoro (2-methyl-2-propyl-1-, 3-dioxole) (where j is 2 in the following formula (8)),

Perfluoro (2-methyl-2-pentyl-1,3-dioxole) (where j is 4 in the following formula (8)).

(7) Examples of the monomer (b) other than the monomer (b-1) (8) include PDD, perfluoro (2-methyl-1,3-dioxol) and the like.

 Among the monomers (b), the synthesis of PDD is disclosed in US Pat. No. 3,865,845. The synthesis of the copolymer is disclosed in US Pat. No. 3,978,030. The synthesis method of the other monomer (b) is disclosed in JP-A-2-117672, JP-A-5-194655, and the like.

 The amorphous fluorine resin (A) of the core preferably contains a high refractive index agent. The high refractive index agent must have a higher refractive index than the fluoropolymer constituting the amorphous fluororesin (A) and have a high affinity for the fluoropolymer. Having high affinity means that it is sufficiently dissolved in the fluoropolymer, has no insoluble matter, and has no possibility of generating a micro phase-separated structure. If such an insoluble matter-mic phase separation structure exists, that part causes light scattering. Therefore, as the high refractive index agent, a compound which is blended with the core fluoropolymer in an amount equal to or less than its saturation solubility and which can sufficiently increase the refractive index of the amorphous fluororesin (A) in the core is used. Is done.

Since the high refractive index agent has a high affinity, a fluorine compound having a relatively low molecular weight is preferred. Further, it preferably has a chlorine atom, an aromatic nucleus, a metal component, and the like because of a high refractive index. Particularly, a compound having a chlorine atom and / or an aromatic nucleus is preferable. Further, the high refractive index agent is preferably a compound having substantially no hydrogen atom as in the case of the fluoropolymer. Thereby, the transmission loss reduction in the near infrared region of the amorphous fluororesin containing the high refractive index agent is maintained. For these reasons, it is preferable that the high-refractive-index agent is a relatively low-molecular-weight fluorine compound having substantially no hydrogen atom and having a chlorine atom and Z or an aromatic nucleus. The molecular weight of the high refractive index agent is preferably 2000 or less, and for polymers such as oligomers, the average molecular weight is preferably 2000 or less. Examples thereof include a fluorinated compound having a chlorine atom, a fluorinated aromatic compound, a fluorinated condensed polycyclic compound, and a metal chelate compound. Preferred high refractive index agents are a fluorine compound having substantially no hydrogen atom and having a chlorine atom, and a fluorine-containing aromatic compound having substantially no hydrogen atom. More preferred are fluorine-containing aromatic compounds having substantially no hydrogen atoms, and among them, perfluoroaromatic compounds having 3 to 5 benzene nuclei in one molecule are particularly preferred. These high refractive index agents can be used alone or in combination of two or more.

 Examples of the fluorinated condensed polycyclic compound include perfluoroanthracene, perfluorinated fluorene, perfluorophenalene, perfluorophenanthrene and the like.

 Examples of the metal chelate compound include perfluoro (tetraphenyltin).

 Examples of the fluorine compound having a chlorine atom include pentafluorobenzene, chloroperfluoronaphthalene, and trifluoroethylene oligomer having an average molecular weight of 200 or less. As the trifluoroethylene oligomer, commercially available one having an average molecular weight of 2000 or less can be used, or it can be obtained by collecting a fraction having an average molecular weight of 2000 or less by distillation.

 Perfluoro (triphenylphosphine), perfluorobenzophenone, perfluorobiphenyl, perfluoroterphenyl, perfluoro (diphenylsulfide), perfluoro (2,4) , 6-trifluorene 1,3,5-triazine), perfluoro (1,3,5-triphenylbenzene) (hereinafter referred to as TPB). Of these, perfluoro (2,4,6-triphenyl 1,3,5-triazine) or TPB is preferable, and TPB is particularly preferable because of its high affinity with the fluoropolymer.

In the amorphous fluororesin containing the high refractive index agent (A), the ratio of the high refractive index agent in the amorphous fluororesin (A) is preferably such that the amorphous fluororesin (樹脂) Is it not less than the amount that reaches the refractive index and not more than the solubility of the high refractive index agent in the fluoropolymer? There is no particular limitation. Usually, it can be contained in the amorphous fluororesin (A) in an amount of 30% by mass or less. The preferred content is 1 to 20% by mass, and particularly preferably contains 5 to 20% by mass of a high refractive index agent.

 It is preferable that the amorphous fluorine resin (B) of the clad contains a fluorine-containing plasticizer having substantially no hydrogen atoms. Fluorine-containing plasticizers soften the amorphous fluororesin in the clad to improve the workability of SI-type optical fibers, and also provide features such as making cracks less likely to occur in large-diameter fibers. . In addition, the addition of a fluorine-containing plasticizer having a high fluorine content has an effect of further lowering the refractive index of the amorphous fluorine resin of the clad.

 As the fluorinated plasticizer, perfluoropolyethers and the like are preferable. Examples of perfluoropolyethers include perfluoro (polyoxyalkylene alkyl ether). Specific examples of perfluoropolyethers include Crytox (trade name, manufactured by Dupont), Demnum (trade name, manufactured by Daikin Industries), Fomblin (trade name, manufactured by Audimont), and the like. The average molecular weight is preferably at least 100, from the viewpoint that it is difficult to volatilize during molding or use. The upper limit of the molecular weight is not particularly limited, but is preferably 20000 or less from the viewpoint of compatibility with the fluoropolymer of the clad.

 In the amorphous fluorine-containing resin (B) containing a fluorine-containing plasticizer, the ratio of the fluorine-containing plasticizer in the amorphous fluorine-containing resin (B) is such that the amorphous plasticizer (B) has a desired plasticizing effect. The amount is not particularly limited as long as it is an amount that achieves the above and is not more than the amount of solubility of the fluoroplastic in the fluoropolymer. Usually, it can contain 50% by mass or less in the amorphous fluorine-containing resin (B). The preferred content is 1 to 40% by mass, particularly preferably 5 to 40% by mass of a fluorinated plasticizer.

 The amorphous fluororesin (A) is preferably composed of a cyclized polymer as described above. The refractive index of the cyclized polymer itself constituting the amorphous fluororesin (A) is preferably at least 1.330, particularly preferably at least 1.335. There is no particular upper limit for the refractive index of the cyclized polymer itself, but it is usually 1.45.

When the refractive index of the cyclized polymer itself is sufficiently high, the amorphous fluorinated resin (A) can be composed of the cyclized polymer alone without including a high refractive index agent. Refraction of the cyclized polymer itself When the refractive index is not sufficiently high or when the refractive index of the amorphous fluororesin (B) is relatively high and the refractive index difference with the cyclized polymer is not large, the amorphous fluororesin containing a high refractive index agent is used. It is preferable to use (A). The refractive index of the amorphous fluororesin (A) which may contain a high refractive index agent is preferably 1.340 or more, more preferably 1.345 or more, still more preferably 1.350 or more, and most preferably 1.355 or more. preferable. The upper limit of the refractive index of the amorphous fluororesin (A) is not particularly limited, but is usually 1.5.

 In the present invention, the amorphous fluororesin (A-1) composed of a fluoropolymer substantially having no hydrogen atom and having a chlorine atom in a side chain is the same as that of the amorphous fluororesin (A). Of these, it is composed of a fluoropolymer having a chlorine atom in the side chain. Since the amorphous fluororesin (A) is preferably a cyclized polymer, the amorphous fluororesin (A-1) is also preferably a cyclized polymer. The fluorine-containing polymer having a chlorine atom in its side chain has a refractive index of 1.345 or more, preferably 1.350 or more. Similarly, the refractive index of the amorphous fluororesin (A-1) is preferably 1.345 or more, particularly preferably 1.350 or more.

 Examples of the fluorine-containing polymer having a chlorine atom in a side chain, which constitutes the amorphous fluororesin (A-1), include a polymer containing a cyclic unit of a monomer (a-1) (see below). The monomer (a-2) may have a cyclically polymerized repeating unit), and other carbons having no chlorine atom directly bonded to the carbon atom constituting the polymerizable double bond A polymer containing a repeating unit in which a copolymerizable monomer having a chlorine atom in the atom (particularly, a monoene containing such a chlorine atom) is polymerized and a repeating unit in which the monomer (a) is cyclopolymerized. And are preferred. As the chlorine atom-containing copolymerizable monomer, monomer (c) is particularly preferred. The monomer having no chlorine atom among the monomers (a) is hereinafter referred to as a monomer (a-2).

Particularly preferred fluorine-containing polymers having a chlorine atom in the side chain are polymers having a repeating unit in which the monomer (a-1) is cyclopolymerized (provided that the monomer (a-2) is a cyclopolymer. And a polymer having a repeating unit in which the monomer (a-1) is cyclopolymerized and a repeating unit in which the monomer (a-2) is cyclopolymerized, and And a polymer having a repeating unit in which the monomer ( _a ) is cyclopolymerized and a repeating unit in which the monomer (c) is polymerized. Since the amorphous fluororesin (A-1) is composed of a fluorine-containing polymer having a chlorine atom, it has a sufficiently high refractive index without containing a high refractive index agent. However, in some cases, a high refractive index agent may be included. The amorphous fluororesin (A) includes the amorphous fluororesin (A-1) as a category, but particularly when it is composed of a fluoropolymer having no chlorine atom, a high refractive index agent is used. It is preferred to include. Even when the amorphous fluororesin (A) is composed of a fluorine-containing polymer having no chlorine atom, the refractive index difference between the amorphous fluororesin (B) and the amorphous fluororesin (B) combined as a clad is large. In some cases, it is not necessary to include a high refractive index agent.

 The amorphous fluororesin (B) is preferably composed of a dioxo-based polymer as described above. The refractive index of the dioxole polymer is not particularly limited as long as the refractive index difference between the dioxole polymer constituting the amorphous fluororesin (B) and the amorphous fluororesin (A) is large. It is preferable that the refractive index of the dioxole polymer constituting the crystalline fluororesin (B) is less than 1.330, particularly less than 1.310. In order to achieve a higher refractive index difference from the amorphous fluororesin (A), the refractive index of the dioxol-based polymer itself must be less than 1.300, particularly less than 1.296. Is more preferred. The lower limit of the refractive index of the dioxyl polymer itself is not particularly limited, but is usually 1.290. Although not limited to the dioxol-based polymer, an amorphous fluororesin composed of a fluoropolymer having a refractive index of less than 1.300 is hereinafter referred to as an amorphous fluororesin (B-2).

 As described above, the fluorine-containing polymer having a repeating unit in which the monomer (b-1) is polymerized is a fluorine-containing polymer having a repeating unit in which the monomer (b) other than the monomer (b-1) is polymerized. It has a lower refractive index than the base polymer. The amorphous fluororesin (B) composed of a fluoropolymer having a repeating unit in which the monomer (b-1) is polymerized is hereinafter referred to as an amorphous fluororesin (B-3). Further, among the fluorine-containing polymers having a repeating unit in which the monomer (b-1) is polymerized, more preferable polymers have a refractive index of less than 1.300, particularly less than 1.296. It is a polymer.

Therefore, the amorphous fluororesin (B-2) and the fluoropolymer constituting the amorphous fluororesin (B-3) have a repeating unit in which the monomer (b-1) is polymerized and A fluoropolymer having a refractive index of less than 1.300 is preferred. Especially preferred This fluoropolymer has a copolymerization molar ratio of the monomer (b-1) and TFE of 99 to 2

It is a copolymer in the range of 0/1 to 80.

 The refractive index of the amorphous fluororesin (B) which may contain a fluorinated plasticizer is 1.3.

It is preferably less than 30, more preferably less than 1.310. Particularly preferred refractive index of the amorphous fluororesin (B) is less than 1.300, most preferably less than 1.296. The lower limit of the refractive index of the amorphous fluororesin (B) is not particularly limited, but is usually 1.28.

5

 The SI optical fiber of the present invention can be manufactured by a known method for manufacturing an SI optical fiber. For example, it can be produced by the method described in the above-mentioned Japanese Patent No. 2821935. Further, the method of producing a graded index type plastic optical fiber described in Japanese Patent Application Laid-Open No. 8-58488 and Japanese Patent Application Laid-Open No. Molded optical fibers can also be manufactured. For example, an SI type optical fiber manufacturing preform (hereinafter simply referred to as a preform) is manufactured and spun from the preform to form an SI type optical fiber, or an SI type optical fiber is extruded according to a multicolor spinning method. There is a method for producing a fiber.

 The SI optical fiber of the present invention does not increase transmission loss due to water absorption due to the water and oil repellency of fluorine atoms, and has high solvent resistance. In addition, the optical fiber has low transmission loss over a wide wavelength range from the visible region to the near infrared region.

 Further, in the SI type optical fiber of the present invention, the difference in the refractive index between the core and the clad can be made sufficiently large, so that the numerical aperture (NA) can be made 0.415 or more. SI type optical fiber with a large numerical aperture allows light to enter from a wide angle, that is, it can detect signals from a wide angle as a sensor, and can increase the coupling efficiency between the light source and the fiber. Energy can be input and transmitted, and bending loss during transmission can be kept small.

The SI type optical fiber of the present invention can be further used in the form of an optical fiber cord-to-optical fiber cable with a coating, or a bundled optical fiber cable. The SI optical fiber of the present invention can have a transmission loss of 100 db or less (less than or equal to 50 dB / km) at a wavelength of 600 to 160 nm. Such a low level transmission loss in a wide wavelength range of 600 to 160 nm Losing is very advantageous. In other words, by using the same wavelength as the quartz optical fiber, connection with the quartz optical fiber is easy, and compared with the conventional plastic optical fiber, which has to use a wavelength shorter than 600 to 1,600 nm. There is an advantage that an inexpensive light source is required.

 On the other hand, plastic optical fibers have a large fiber diameter and are easy to connect to light sources and light-receiving elements or to fibers. Therefore, expectations for construction of inexpensive short-distance communication systems are increasing. Since the SI type optical fiber of the present invention has remarkably improved heat resistance, it has high thermal stability and can prevent a reduction in transmission loss even when exposed to a high temperature above room temperature for a long time.

(Example)

 Next, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Parts represent parts by mass. Examples 1 to 3 are examples of monomer synthesis in which fluorine-containing dioxols were synthesized. Examples 4 to 27 are polymer production examples for producing a fluorinated polymer constituting an amorphous fluororesin. Examples 28 to 41 are examples of producing an amorphous fluororesin for producing an SI optical fiber. Examples 42 to 58 are examples of producing an SI optical fiber.

 [Example of monomer synthesis]

 (Example 1) Perfluoro (2-methyl-2-propyl-1,3-dioxole)

(Hereinafter referred to as PMPROD).

1.5 kg of 60% fuming sulfuric acid was placed in a 2 L glass four-necked flask, and 446 g of CF ₃ (CF ₂ ) ₅ I was added dropwise using a dropping funnel. Stirring was maintained for 24 hours at 65 ° C. After completion of the reaction, the mixture was cooled and separated into two phases. Only the upper layer was collected and distilled to obtain 190 g (60% yield) of colorless and transparent CF ₃ (CF ₂ ) ₄ C〇F. Next, put 1 L of ethanol and a few drops of phenolphthalein into a 2 L polypropylene beaker, and stir with a magnetic stirrer to obtain CF ₃ (CF ₂ ) ₄ CO

190 g of F was added dropwise. An ethanol solution of 10% sodium hydroxide was added dropwise to the solution until the solution became neutral. Ethanol was removed from the obtained reaction solution using an evaporator, and the obtained solid was transferred to a vacuum dryer, and vacuumed at 100 for 18 hours. Drying was performed. Next, the solid after vacuum drying was transferred to a 5 L glass flask, and the flask was heated through a dry ice trap under reduced pressure using a vacuum pump in an oil bath at 250 to 270 ° C for 24 hours. Continued. By distilling trapped in the dry ice trap liquid, a _{CF 3 CF 2 CF 2 CF =} CF 2 1 1 3 g (75% yield).

Next, 1000 g of a 15% aqueous solution of sodium hypochlorite and 8 g of trioctylmethylammonium chloride were placed in a 2 L glass four-neck flask, and the mixture was cooled with sufficient stirring until the internal temperature reached 10 to 15. . To the solution, 113 g of CF ₃ CF ₂ CF ₂ CF = CF ₂ was added dropwise to keep the internal temperature at 20 to 30 ° C. Then, the reaction was continued until the starting material, CF ₃ CF ₂ CF ₂ CF = CF _{2, was} almost consumed, while tracking the reaction by gas chromatography. The lower layer product was extracted by two-phase separation, and washed three times with ion-exchanged water to remove residual sodium hypochlorite. The crude product was further distilled to obtain 83 g of pure fluorinated epoxide (perfluoro (1,2-epoxypentane)) (yield 70%).

Next, 3 g of aluminum chloride was placed in a 20 OmL glass four-necked flask, and activated by adding 10 g of trichlorofluoromethane. Then, 83 g of the fluorinated epoxide synthesized above was dropped while keeping the internal temperature at 20 to 30 ° C while stirring well. Thereafter, the reaction was carried out at a reaction temperature of 20 to 40 ° C. until the starting material was almost consumed, while following the reaction by gas chromatography. Subsequently, the crude product was isolated by filtration and distilled to obtain 76 g of pure CF ₃ CF ₂ CF ₂ COCF ₃ (yield 92%).

Next, 25 g of 2-chloroethanol was placed in a 30 OmL glass four-necked flask, and 76 g of CF ₃ CF ₂ CF ₂ COCF ₃ was added dropwise with stirring at room temperature. The resulting crude reaction solution was added dropwise to 500 g of a 20% aqueous sodium hydroxide solution in another 1 L glass flask with vigorous stirring. The reaction mixture was washed three times with water and distilled to obtain 77 g (yield) of the desired dioxolane compound (4,4,5,5-tetrahydro-perfluoro (2-methyl-2-propyl-1,3-dioxolane)). Rate 87%).

Next, a stirrer, a dry ice reflux condenser, a chlorine gas injection pipe, and a thermocouple temperature 77 g of the above dioxolane compound was placed in a 50 OmL glass four-necked flask equipped with a degree meter, and chlorine gas introduction was started at 5 ° C. At the beginning of the reaction, chlorine was introduced slowly because the reaction was intense. The temperature was gradually raised, and the reaction was continued at 78 ° C at the end, and the reaction was terminated when the chlorine was no longer consumed. 100 g (yield 89%) of the obtained tetraclo-mouth dioxolane compound (4,4,5,5-tetraclo-mouth-perfluoro (2-methyl-2-propyl-1,3-dioxolane)) was obtained without purification. It was used for the next reaction as it was.

 Next, in a 50 OmL glass three-necked flask equipped with a stirrer, a reflux condenser, and a thermocouple thermometer, 50 g of antimony trifluoride, 5 g of antimony pentachloride, and perfluoro (21-butyltetrahydrofuran) as a solvent ( Then, 100 g of the above tetrachlorodioxolane compound was added at room temperature, and the mixture was refluxed for 24 hours. Under these conditions, only the desired compound in which the two chlorines at the vicinal position were substituted with fluorine was selectively obtained. After cooling to room temperature, only the supernatant is collected by decantation and distilled under reduced pressure to obtain the desired dichlorodioxolane compound (4,5-dichloromouth-perfluoro (2-methyl-2-propyl-1,3 —Dioxolane)) was obtained in an amount of 78 g (yield 85%).

 Next, in a 1L glass four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermocouple thermometer, put 15 g of magnesium powder, 1 g of iodine, and 0 g of mercuric chloride.

5 g and 35 OmL of tetrahydrofuran were added and heated using a mantle heater. When the reflux started, the heating was stopped and the above dichlorodioxolane compound was slowly dropped in 78 g. The reactor was cooled as needed due to vigorous heat generation. After completion of the dropwise addition, the pressure in the reaction vessel was reduced, and tetrahydrofuran and products were collected by a liquid nitrogen trap. Pour the collected material into cold water and separate the lower fluorocarbon phase.

By distillation under reduced pressure, 25 g (yield: 40%) of the target PMPROD having 99.5% purity (j in the formula (8) was 2) was obtained. This was used for the following polymerization.

 (Example 2) Perfluoro (2-methyl-2-pentyl-1,3-dioxol)

(Hereinafter referred to as PMPEND).

1.5 kg of 60% fuming sulfuric acid is placed in a 2 L glass four-necked flask, and a dropping funnel is added. Using, 546 g of CF ₃ (CF ₂ ) ₇ I was added dropwise. Stirring was maintained for 20 hours at 65 ° C. After completion of the reaction, the mixture was cooled and separated into two phases. Thus, only the upper layer was collected and distilled to obtain 270 g (65% yield) of colorless and transparent CF ₃ (CF ₂ ) ₆ COF. Next, several drops of 1 L of ethanol and phenolphthalein were added to a 2 L polypropylene beaker, and 270 g of CF ₃ (CF ₂ ) ₆ COF was added dropwise while stirring with a magnetic mixer. An ethanol solution of 10% sodium hydroxide was added dropwise to the solution until the solution became neutral. Ethanol was removed from the obtained reaction solution using an evaporator, and the obtained solid was transferred to a vacuum drier and dried under vacuum at 100 ° C for 15 hours. Next, the solid after vacuum drying was transferred to a 5-L glass flask, and the flask was heated for 24 hours in an oil bath under reduced pressure using a vacuum pump through a dry ice trap while maintaining the temperature at 260 to 280 ° C. Continued. By distilling the liquid collected in the dry ice trap, CF ₃ (CF ₂ ) ₄ CF = CF ₂ (180 g, yield 79%) was obtained.

Next, 1000 g of a 15% aqueous solution of sodium hypochlorite and 10 g of trioctylmethylammonium chloride are placed in a 2 L glass four-necked flask, and the internal temperature is reduced to 10 to 15 ° C while stirring well. Allowed to cool. There, 180 g of CF ₃ (CF ₂ ) ₄ CF = CF ₂ was added dropwise to keep the internal temperature at 20 to 30. Subsequently, the mixture was allowed to react until CF ₃ as a raw material while monitoring the reaction by gas chromatograph (CF _{2) 4} Ji = Ji is ₂ approximately consumed. The lower layer product was extracted by two-phase separation, and washed three times with ion-exchanged water to remove residual sodium hypochlorite. By further distilling the crude product, 122 g (yield 65%) of pure fluorine-containing epoxide (perfluoro (1,2-epoxyheptan)) was obtained.

Next, 3 g of aluminum chloride was placed in a 20 OmL glass four-necked flask, and activated by adding 10 g of trichlorofluoromethane. Thereto, 120 g of the fluorinated epoxide synthesized above was added dropwise while stirring well so as to keep the internal temperature at 20 to 30 ^. Thereafter, the reaction was carried out at a reaction temperature of 20 to 40 ° C. until the starting material was almost consumed, while following the reaction with a gas chromatograph. Subsequently, the crude product was isolated by filtration and distilled to obtain 108 g (yield 90%) of pure CF ₃ (CF ₂ ) ₄ COCF ₃ . Next, 23 g of 2-chloroethanol was placed in a 30 OmL glass four-necked flask, and 108 g of CF ₃ (CF ₂ ) ₄ COCF ₃ was added dropwise at room temperature with stirring. The resulting crude reaction solution was added dropwise to 500 g of a 20% aqueous sodium hydroxide solution in another 1 L glass flask with vigorous stirring. The reaction solution is washed three times with a separating funnel and distilled to obtain the desired dioxolane compound (4,4,5,5-tetrahydro-perfluoro (2-methyl_2-pentyl-1,3-). 103 g (yield 85%) of dioxolane)). -Next, put 103 g of the above dioxolane compound into a 50-mL 4-neck glass flask equipped with a stirrer, dry ice reflux condenser, chlorine gas injection tube, and thermocouple, and introduce chlorine gas at 5 ° C. I started. At the beginning of the reaction, chlorine was introduced slowly because the reaction was intense. The temperature was gradually raised, and the reaction was continued at 80 ° C at the end. The reaction was terminated when chlorine consumption was no longer being used. 121 g (yield: 88%) of the obtained tetraclo-mouthed dioxolane compound (4,4,5,5-tetrachloro-perfluoro (2-methyl-2-pentyl-1,3-dioxolane)) was obtained. It was used for the next reaction without purification.

Next, in a 50 OmL glass three-necked flask equipped with a stirrer, a reflux condenser, and a thermocouple thermometer, put 50 g of antimony trifluoride, 5 g of antimony pentachloride, and 5 OmL of PBTHF as a solvent, and bring to room temperature Then, 12 lg of the tetraclo-mouthed dioxolane compound was added, and the mixture was refluxed for 32 hours. Under these conditions, only the desired compound in which two chlorine atoms at the vicinal position were substituted with fluorine was selectively obtained. After cooling to room temperature, only the supernatant is collected by decantation and distilled under reduced pressure to obtain the desired dichlorodioxolane compound (4,5-dichloro-perfluoro (2-methyl-2-pentyl). — 1, 3-dioxolane)) 99 g (87% yield). Next, magnesium powder 13 g, iodine 2 g, mercuric chloride 0.5 g, tetrahydrofuran 35 OmL were placed in a 1 L glass four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermocouple. And heated using a mantle heater. When the reflux started, the heating was stopped and 99 g of the above dichlorodioxolane compound was slowly added dropwise. The reactor was cooled as needed due to vigorous heat generation. End of dripping After completion, the pressure in the reaction vessel was reduced, and tetrahydrofuran and products were collected by a liquid nitrogen trap. Pour the collected material into cold water and separate the lower fluorocarbon phase.

By distillation under reduced pressure, 34 g (41% yield) of the desired PMPEND having a purity of 99.2% (j was 4 in the above formula (8)) was obtained. This was used for the following polymerization.

 (Example 3) Synthesis of perfluoro (2-pentyl-1,3-dioxole) (hereinafter referred to as PPD).

1.5 kg of 60% fuming sulfuric acid was placed in a 2 L glass four-necked flask, and 446 g of CF ₃ (CF ₂ ) ₅ I was added dropwise using a dropping funnel. Stirring was maintained at 65 ° C for 18 hours. After completion of the reaction, the mixture was cooled and separated into two phases. Only the upper layer was collected and distilled to obtain 200 g (63% yield) of colorless and transparent CF ₃ (CF ₂ ) ₄ CF.

Next, 51 g of 2-hydroxyethanol was added to 1 L polypropylene bicarbonate, 200 g of CF ₃ (CF ₂ ) ₄ COF was added dropwise, 50 g of pyridine was added, and the mixture was washed with water. By distillation, 190 g (yield 80%) of CF ₃ (CF ₂ ) ₄ COOCH ₂ CH ₂ C 1 was obtained.

Next, into a 1 L glass four-necked flask, 50 OmL of dimethyl sulfoxide and 7.3 g of sodium hydride (dispersed in 60% mineral oil) were placed, and while stirring, 190 g of CF ₃ (CF _{3 2} ) ₄ CO〇CH ₂ CH ₂ C 1 was added to keep the temperature below 20 ° C. The stirring was continued while maintaining the temperature at 30 ° C. or lower. By distillation under reduced pressure, 86 g (yield 50%) of the desired dioxolane compound (2,4,4,5,5-pentylhydrazine-perfluoro (2-pentyl-1,3-dioxolane)) was obtained. .

Next, 86 g of the dioxolane compound was placed in a 50-mL glass four-necked flask equipped with a stirrer, a dry ice reflux condenser, a chlorine gas injection tube, and a thermocouple thermometer. At the beginning of the reaction, chlorine was introduced slowly because the reaction was intense. The temperature was gradually increased, and the reaction was continued at 82 ° C at the end, and the reaction was terminated when the chlorine consumption was stopped. 95 g (yield 74%) of the obtained pentachlorodioxolane compound (2,4,4,5,5-pentachloroperfluoro (2-pentyl-1,3-dioxolane)) was directly used without purification. Next reaction It was used for.

 Next, 50 g of antimony trifluoride, 5 g of antimony pentachloride, and 5 OmL of PBTHF as a solvent were placed in a 50-mL three-neck glass flask equipped with a stirrer, a reflux condenser, and a thermocouple thermometer. 95 g of a pentachlorodoxolan compound was added, and reflux was continued for 24 hours. Under these conditions, only compounds in which the chlorine at the 2-position and the two chlorines at the vicinal position were substituted with fluorine were selectively obtained. After cooling to room temperature, only the supernatant is collected by decantation and distilled under reduced pressure to obtain the desired dichlorodioxolane compound (4,5-dichloro-perfluoro (2-pentyl-1,3). —Dioxolane)) 73 g (85% yield).

 Next, in a 1L glass four-necked flask equipped with a stirrer, reflux condenser, dropping port, and thermocouple, 15 g of magnesium powder, 0.5 g of iodine lg, 0.5 g of mercuric chloride, and 35 OmL of tetrahydrofuran And heated using a mantle heater. When the reflux started, the heating was stopped and 73 g of the above dichlorodioxolane compound was slowly added dropwise. The reactor was cooled as needed due to vigorous heat generation. After completion of the dropwise addition, the pressure in the reaction vessel was reduced, and tetrahydrofuran and products were collected by a liquid nitrogen trap. The collected matter was poured into cold water, the lower fluorocarbon phase was separated, and 22 g (yield 35%) of the target PPD (formula (9)) having a purity of 99.7% was obtained by distillation under reduced pressure. This was used for the following polymerization.

_{^{19 F- NMR (CDC 1 3,}} CFC 1 3 reference) S ppm; - 70. 1 ( 1 F),

— 80. 9 (3 F), -121. 8 to 1 126.0 (9F),-157.9 (1

F).

 [Polymer production example]

In Examples 4 to 28 below, the glass transition temperature T _g of the fluoropolymer or the amorphous fluororesin was measured using differential scanning calorimetry (based on JI S_K7121). . The refractive index was measured using an Abbe refractometer. The molecular weight was measured as a number average molecular weight _{Mn in} terms of polymethyl methacrylate by gel permeation chromatography (GPC) using a dichloro-opening pen-fluorfluoropropane solvent (hereinafter referred to as R225). The intrinsic viscosity [77] (unit: dlZg) was measured at 30 ° C. by dissolving in PBTHF (R 225 for the polymer P-4 obtained in Example 7).

 In the following polymer production examples, the fluorination treatment of the polymer is basically performed by treating the polymer in an atmosphere of a mixed gas of fluorine and nitrogen (fluorine gas concentration: 20% by volume) at 250 ° C for 5 hours. Yes (specify if the conditions are changed).

 (Example 4) Polymer P-1 (BVE polymer)

A 5 L glass flask was charged with 750 g of BVE, 4 kg of ion-exchanged water (hereinafter also referred to as water), 260 g of methanol, and 3.7 g of diisopropylperoxydicarbonate. After purging the system with nitrogen, suspension polymerization was carried out at 40 ° C. for 22 hours to obtain 690 g of a polymer having an _Mn of about 5 × 10 ⁴ . By subjecting this polymer to fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-1) was obtained. Of the polymer P- 1 [] is 0. 25, T _g is 108 ° C, the refractive index 1. a 342 was a transparent vitreous polymer tough at room temperature.

 (Example 5) Polymer P-2 (8 ¥ £-41 ^ [Polymer)

A glass ampoule was charged with 2 g of BVE-4M and 6.2 mg of diisopropylperoxydicarboxylic acid, frozen in liquid nitrogen, degassed under vacuum, and sealed. After heating in an oven at 40 ° C for 20 hours, the solidified contents were taken out and dried at 200 for 1 hour. The yield of the obtained polymer was 99%. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-2) was obtained. [??] of the polymer P-2 was 0.44, _Mn was 131,500, the refractive index was 1.33, and T _g was 124 ° C. The tensile properties of polymer P-2 are tensile modulus of elasticity of 14 3 OMPa yield stress of 36 MPa, elongation at break of 4.2%, and zero shear viscosity at 230 ° C of 89,000 Pa · was s

(Example 6) Polymer P-3 (BVEZBVE-4M copolymer)

80 g of water in a 20 OmL autoclave: 6 £ -4 ^ 15, BVE 15 g, 75 mg of perfluorobenzoylperoxide and 2.4 g of methanol were added. After the autoclave was replaced with nitrogen, the autoclave was heated until the internal temperature of the autoclave reached 70 ° C., and polymerization was carried out for 20 hours. The obtained polymer was washed with water and methanol, and then dried at 200 ° C for 1 hour. The yield of the obtained polymer was 85%. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-3) was obtained. [??] of the polymer P-3 was 0.35, the refractive index was 1.336, and the _Tg was 116 ° C.

 (Example 7) Polymer P-4 (8 ¥ £ -4

5 g of BVE-4CL and 12.5 mg of diisopropylperoxydicaponate were placed in a glass ampule, frozen in liquid nitrogen, vacuum-degassed, and sealed. After heating in an oven at 40 ° C for 20 hours, the solidified contents were taken out and dried at 200 ° C for 1 hour. The yield of the obtained polymer was 80%. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-4) was obtained. [77] of the polymer P- 4 is 0.5 is 20, M _n 121500, the refractive index is 1. 372, T _g was 126 ° C. The tensile properties of the polymer P-4 were a tensile modulus of 170 OMPa, a yield stress of 5 OMPa, and a yield elongation of 3.8%.

 (Example 8) Polymer P-5 (BVEZBVE-4 CL copolymer)

A 20 OmL autoclave was charged with 80 g of water, 20 g of BVE-4CL, 15 g of BVE, 8 Omg of perfluorobenzoylperoxide, and 2.O g of methanol. After the autoclave was replaced with nitrogen, the autoclave was heated until the internal temperature reached 70 ° C., and polymerization was carried out for 24 hours. The obtained polymer was washed with water and methanol, and then dried at 200 ° C for 1 hour. The yield of the obtained polymer was 80%. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-5) was obtained. The polymer P- 5 [] is 0.30, the refractive index 1. 36, T _g was 120.

 (Example 9) Polymer P-6 (BVE-4DCL polymer)

A 10 OmL stainless steel autoclave was charged with 50 g of trichloro- mouth trifluoroethane, 30 g of BVE-4DCL, and 0.1 g of diisopropylperoxydicarbonate. The autoclave was heated and stirred at 50 ° C for 3 days. After that, the autoclave was opened and washed with methanol. The obtained polymer was taken out, and the solvent and the residual monomer were distilled off under reduced pressure to obtain 29 g of a colorless and transparent polymer. The yield of the obtained polymer was 96%. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-6) was obtained. ] \ ^ Of the polymer P-6 was 123000, the refractive index was 1.1, and T _g was 168 ° C. The tensile properties of the polymer P-6 were a tensile modulus of 1690 MPa, a yield stress of 50 MPa, and a yield elongation of 3.6%.

(Example 10) Polymer P-7 (8 ¥ £ / ^/ 8 ¥ £ — 40〇 copolymer)

A 20 OmL autoclave was charged with 80 g of water, 22 g of BVE-4 DCL, 15 g of BVE, 75 mg of perfluorobenzoylperoxide, and 2.0 g of methanol. After the autoclave was replaced with nitrogen, the autoclave was heated until the internal temperature reached 70 ° C., and polymerization was carried out for 28 hours. The obtained polymer was washed with water and methanol, and then dried at 200 ° C for 2 hours. The yield of the obtained polymer was 80%. By subjecting this polymer to a fluorination treatment, a polymer having excellent light transmittance and thermal stability (hereinafter referred to as polymer P-7) was obtained. [Τί] of the polymer P-7 was 0.28, the refractive index was 1.38, and the T _g was 145.

 (Example 11) Polymer P_8 (BVE / 2 CLBVE copolymer)

A 20 OmL autoclave was charged with 80 g of water, 12 g of 2 CLBVE, 15 g of BVE, 75 mg of perfluorobenzoylperoxide, and 1.0 g of methanol. After the autoclave was replaced with nitrogen, the autoclave was heated until the internal temperature reached 75 ° C., and polymerization was carried out for 40 hours. The obtained polymer was washed with water and methanol, and then dried at 200 for 2 hours. The yield of the obtained polymer was 70%. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-8) was obtained. [??] of the polymer P_8 is 0.25, the refractive index is 1. 35, T _g was 98 ° C.

 (Example 12) Polymer P-9 (PDDZTFE copolymer)

PDD and TFE mass ratio of 80: 20, and the radical Le polymerization using a PB THF as the solvent, T _g is the M _n in 160 ° C to obtain a polymer of about 1. 7X 10 ^5. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and heat stability (hereinafter referred to as “polymer”) is obtained. Coalescence P-9). Polymer P-9 was colorless and transparent, and had a refractive index of 1. SO 5.

 (Example 13) Polymer P-10 (PMPROD / TFE copolymer)

The PMPROD and TFE mass ratio of 85: 15, and the radical polymerization using a PB TH F as the solvent, T _g is the M _n in 200 ° C to obtain a polymer of about 1. ⁵ X 10 5. By subjecting this polymer to fluorination treatment (the treatment time was 7 hours), a polymer having good light transmittance and heat stability (hereinafter referred to as polymer P-10) was obtained. Polymer P-10 was colorless and transparent, and had a refractive index of 1.298.

 (Example 14) Polymer P-11 (PMPENDZTFE copolymer)

The PMPEND and TFE mass ratio of 85: 15, and the radical polymerization using a P BTHF as solvent, T _g is the M _n in 190 ° C to obtain a polymer of about l 3X 10 ^5.. By subjecting this polymer to a fluorination treatment (the treatment time was 6 hours), a polymer having good light transmittance and heat stability (hereinafter referred to as polymer P-11) was obtained. Polymer P-11 was colorless and transparent, and had a refractive index of 1.295.

 (Example 15) Polymer P-12 (PDDZBVE-4M copolymer)

Radical polymerization of PDD and BVE-4M at a mass ratio of 50:50 using PB THF as a solvent yielded a polymer having a T _g of 170 ° C and a [77] of 0.34. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-12) was obtained. Polymer P-12 was colorless and transparent, and had a refractive index of 1.320.

 (Example 16) Polymer P-13 (PMPRODZBVE-4M copolymer)

Radical polymerization of PMPROD and BVE-4M at a mass ratio of 45:55 using PBTHF as a solvent yielded a polymer having a T _g of 160 ° C and [] of 0.32. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-13) was obtained. Polymer P-13 was colorless and transparent, and had a refractive index of 1.318.

 (Example 17) Polymer P-14 (PMPENDNO BVE-4M copolymer)

PMPEND and BVE- 4M mass ratio of 50: 50 in PB TH F to radical polymerization have use as solvents, T _g is [7] is 162 ° C to obtain a polymer of 0.37. this By subjecting the polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P_l4) was obtained. Polymer P-14 was colorless and transparent, and had a refractive index of 1.319.

 (Example 18) Polymer P-15 (PPD / BVE-4M copolymer)

 Radical polymerization of PPD and BVE-4M at a mass ratio of 55:45 using PB THF as a solvent yielded a polymer of 1 = 160 and [7?] = 0.33. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-15) was obtained. Polymer P_15 was colorless and transparent, and had a refractive index of 1.310.

 (Example 19) Polymer P-16 (PDDZPHVE copolymer)

 PDD and perfluoro (3,6-dioxa-1-methyl-1-nonene) (CF

₂ = Radical polymerization of CF-0-CF (CF ₃ ) -CF ₂ -0-CF ₂ -CF ₂ -CF ₃ ) (hereinafter referred to as PH VE) at a mass ratio of 85:15 using PBTHF as a solvent, A polymer having _g of 182 and [] of 0.38 was obtained. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P- 16) was obtained. Polymer P-16 was colorless and transparent, and had a refractive index of 1.300.

 (Example 20) Polymer P-17 (PMPRODZBVE copolymer)

PMPROD and BVE mass ratio of 50: 50 in PB THF and La radical polymerization using a solvent, T _g is at 145 ° C [? 7] to obtain a polymer of 0.30. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-17) was obtained. Polymer P-17 is colorless and transparent, and has a refractive index of 1.

It was 321.

 (Example 21) Polymer P_ 18 (PMPENDZBVE copolymer)

Radical polymerization of PMPEND and BVE at a mass ratio of 50:50 using PBTHF as a solvent gave a polymer with 1 at 150 ° and [77] at 0.32. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-18) was obtained. Polymer P-18 was colorless and transparent, and had a refractive index of 1.320. (Example 22) Polymer P-19 (PPD / BVE copolymer)

Radical polymerization of PPD and BVE at a mass ratio of 50:50 using PBTHF as a solvent yielded a polymer having a T _g of 148 ° C and a [??] of 0.35. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-119) was obtained. Polymer P-19 was colorless and transparent, and had a refractive index of 1.322.

 (Example 23) Polymer P-20 (PDD / MMD copolymer)

PDD and MMD mass ratio 65: 35 PB TH F radical polymerization using as solvent, T _epsilon is at 170 ° C [77] is to obtain a polymer of 0.30. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P_20) was obtained. Polymer P-20 was colorless and transparent, and had a refractive index of 1.325.

 (Example 24) Polymer P-21 (PMPROD / MMD copolymer)

PMPROD and MMD mass ratio 65: 35 in PB THF and La radical polymerization using a solvent, T _g is [? 7] is 168 ° C to obtain a polymer of 0.31. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-21) was obtained. Polymer P-21 was colorless and transparent, and had a refractive index of 1.324.

 (Example 25) Polymer P-22 (PMPENDZMMD copolymer)

Radical polymerization of PMPEND and MMD at a mass ratio of 60:40 using PBTHF as a solvent gave a polymer with a T _g of 142 and a [7?] Of 0.38. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-22) was obtained. Polymer P-22 was colorless and transparent, and had a refractive index of 1.327.

 (Example 26) Polymer P-23 (PPDZMMD copolymer)

Mass PPD and MMD ratio 65: 35 PB THF radical polymerization using as solvent, T _g is [77] is to obtain a polymer of 0 - 29 162. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-23) was obtained. Polymer P-23 is colorless and transparent, with a refractive index of 1.325 Met.

 (Example 27) Polymer P-24 (PPDZTFE copolymer)

PPD and TFE mass ratio of 85: [? 7] 15 P BTHF radical polymerization using a solvent, T _g is at 162 ° C to obtain a polymer of 0.35. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-24) was obtained. Polymer P-24 was colorless and transparent, and had a refractive index of 1.307.

 (Example 28) Polymer P-25 (PPD polymer)

5 g of PPD, 6.0 mg of sulfuryl chloride, and 5.0 mg of diisopropylperoxydicarbonate were placed in a glass ampoule, frozen in liquid nitrogen, vacuum-degassed, and sealed. After heating in an oven at 40 for 3 hours, the solidified contents were taken out and dried at 200 ° C for 1 hour. The yield of the obtained polymer was 97%. By subjecting this polymer to a fluorination treatment, a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-25) was obtained. [77] of the polymer P-4 was 0.87, _Mn was 105000, the refractive index was 1.320, and T _g was 105 ° C. The tensile properties of the polymer P-4 were a tensile modulus of 500 MPa and an elongation at break of 63%.

 [Amorphous fluororesin production example]

 (Examples 29 to 42) Resin R—1 to Resin R—14

Polymer P-1 and TPB were mixed (the latter was contained at 7.4% by mass with respect to the total of both), and melt-blended at 250 to produce a uniform mixture. Hereinafter, this mixture is referred to as resin R-1. Resin R-1 had a refractive index of 1.357 and a T _g of 90 ° C. In the same manner as described above, the polymer and the additive were melt-mixed to produce a uniform mixture. The resulting mixtures were named Resin R-2 to Resin R-15, and Table 1 shows the composition, refractive index, and _Tg (° C) including Resin R_1. "Amount of additive" in Table 1 represents the ratio (% by mass) of the additive in the mixture. The additives used are as follows.

 CFE: Clos trifluoroethylene oligomer having an average molecular weight of 2,000.

PPE: Perfluoropolyether having an average molecular weight of 4000 (trade name “Fonbulin Z 03” manufactured by Audimont). (table 1 )

 [Example of fiber creation]

 In the following example in which an S-type optical fiber was prepared, the numerical aperture (NA) of the obtained S-type optical fiber was measured by the far-field pattern method (based on J13-66862). The transmission loss was measured by the cut-back method at a wavelength of 500 to 160 nm. Fibers were created by the following two methods. Preform method: Cylinder polymer (or resin) is melt-molded at 250 ° C to produce a cylindrical tube, and core polymer (or resin) is melt-molded with 2501: To produce a cylinder having an outer diameter slightly smaller than the inner diameter of the cylindrical tube. A preform is manufactured by inserting the cylindrical body into the hollow portion of the cylindrical tube and heating to 230 ° C to combine the two, and the preform is melt-spun at 250 ° C to form the SI type. Obtain an optical fiber.

Two-layer extrusion spinning method: Using an extruder, the core polymer (or resin) is placed at the center Then, the polymer (or resin) to be the clad is arranged on the outer periphery, and is extruded concentrically at 250T: to obtain the SI type optical fiber.

 (Example 44)

 By the preform method, an SI type optical fiber having a core of polymer P-1 and a clad of polymer P-10, an outer diameter of 100 mm, and a core diameter of 98 O ^ m was obtained. Figure 1 shows the results of measuring the transmission loss of the obtained SI optical fiber. As shown in Fig. 1, the transmission loss of this SI optical fiber is 62 dB / km at 650 nm, 20 dBZkm at 850 nm, and 22 dBZkm at 1300 nm. Was an optical fiber that could transmit the light well. The NA was 0.34. After storing this SI type optical fiber in an oven at 70 for 5000 hours, a heat resistance test for re-measuring the transmission loss showed no change, and the heat resistance was good.

 (Examples 45-54)

In the same manner as in Example 44, an SI type optical fiber was prepared by the preform method. Table 2 shows the types of core and cladding materials, outer diameter and core diameter, transmission loss, and NA of the obtained SI optical fiber. In addition, when a heat resistance test was performed under the same conditions as in Example 44, the transmission loss did not change for any of the SI type optical fibers, and the heat resistance was good.

(Table 2)

 (Example 57)

 By the two-layer extrusion spinning method, an SI optical fiber having a clad of resin R-12 and a core of polymer P-1, an outer diameter of 1000 m and a core diameter of 900 im was obtained. The optical transmission loss of this SI optical fiber is 146 dBZkm at 650 nm, 85 dBZkm at 850 nm, and 71 dB / km at 1300 nm, and can transmit light from visible light to near-infrared light well. Optical fiber. NA was 0.35. After storing this optical fiber in an oven at 80 ° C for 3000 hours, a heat resistance test was performed to measure the transmission loss again. No change was observed, and the heat resistance was good.

 (E.g. 58-70)

In the same manner as in Example 44, an SI type optical fiber was prepared by the preform method. Table 3 shows the types of core and cladding materials, outer diameter and core diameter, transmission loss, and NA of the obtained SI optical fiber. In addition, when a heat resistance test was performed under the same conditions as in Example 44, the transmission loss did not change for any of the SI type optical fibers, and the heat resistance was good. (Table 3)

 (Example 7 1 to 8 0)

Example 4 In the same manner as in Example 4, an SI type optical fiber was prepared by the preform method. Table 4 shows the types of core and cladding materials, outer diameter and core diameter, transmission loss, and NA of the obtained SI optical fiber. In addition, when a heat resistance test was performed under the same conditions as in Example 44, the transmission loss did not change for any of the SI optical fibers, and the heat resistance was good.

(Table 4)

 (Example 81)

 By the two-layer extrusion spinning method, an SI optical fiber having a core of resin R-8 and a clad of resin R_12, an outer diameter of 1000 Aim, and a core diameter of 950 / zm was obtained. The optical transmission loss of this SI type optical fiber is 146 dB / km at 650 nm, 85 dBZkm at 85011111, and 71 dBZkm at 1300 nm, and is an optical fiber that can transmit light from visible light to near-infrared light well. there were. NA was 0.58. When a heat resistance test was performed under the same conditions as in Example 57, the transmission loss did not change and the heat resistance was good. Industrial applicability

The SI optical fiber of the present invention can increase the numerical aperture by increasing the refractive index difference between the core and the cladding without deteriorating the light transmission performance. As a result, the transmission loss during bending is not increased, and when used in a sensor or the like, the light can be collected from a wide range, so that the sensor sensitivity is improved. Also, it can give low level transmission loss over a wide wavelength range of 600 to 1600 nm. In other words, since the same wavelength as the quartz optical fiber can be used, the connection with the quartz optical fiber is easy, and the wavelength of 600 to We have to use shorter wavelengths than 160 nm,

In comparison, there is an advantage that a cheaper light source can be used.

 On the other hand, the SI type optical fiber of the present invention has a large fiber diameter like ordinary plastic optical fiber and can be connected to a light source and a light receiving element or easily connected to each other, so that an inexpensive short distance communication system can be constructed. . Furthermore, since the SI type optical fiber of the present invention has dramatically improved heat resistance as compared with ordinary plastic optical fibers, it has high thermal stability and is exposed to high temperatures above room temperature for a long time. In this case, the transmission loss can be prevented from lowering. Also, since the cladding can have flexibility, a fiber that is less likely to crack can be obtained.

Claims

The scope of the claims 1. The core is made of an amorphous fluororesin (A-1) composed of a fluorine-containing polymer having substantially no hydrogen atoms and having a chlorine atom in the side chain, and the cladding has substantially hydrogen atoms. A step index type plastic optical fiber comprising an amorphous fluororesin (B) composed of a non-fluorinated polymer and having a refractive index difference between the core and the clad of not less than 0.020.  2. The fluorine-containing polymer constituting the amorphous fluororesin (A-1) is a repeating unit obtained by cyclopolymerizing a monomer (a-1) represented by the following formula (1) and having a chlorine atom. A polymer or a repeating unit obtained by cyclopolymerizing a monomer (a) represented by the following formula (1) and a repeating unit obtained by polymerizing a monomer (c) represented by the following formula (2) 2. The step index type plastic optical fiber according to claim 1, which is a polymer having a unit. However, m and n are each independently an integer of 0 to 5, and R ¹ R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a perfluoro group having 1 to 9 carbon atoms. Represents a loalkyl group, a chlorine atom or a fluorine atom. CF ₂ = CF-O-CR ¹ R ^2- (CR ³ R ⁴ ) _m -CF = CF ₂ (1) CF ₂ = CF— O— CR ⁵ R ^6- (CR ⁷ R ⁸ ) _n _CFCl—CF ₂ Cl (2) 3. The fluorinated polymer constituting the amorphous fluororesin (B) is a polymer having a repeating unit in which a monomer (b) represented by the following formula (3) is polymerized. Is a step index type plastic optical fiber described in 2. Here, R ¹¹ and R ¹² each independently represent a perfluoroalkyl group having 1 to 9 carbon atoms or a fluorine atom. (3)

4. The step index type plastic optical fiber according to claim 12, wherein the amorphous fluororesin (B) contains a fluorinated plasticizer having substantially no hydrogen atom.  5. The core contains an amorphous fluororesin (A) composed of a fluorine-containing polymer containing a high-refractive-index agent and having substantially no hydrogen atoms, and the cladding substantially contains a hydrogen atom. Comprising an amorphous fluororesin (B) composed of a fluoropolymer having no core and a refractive index difference between the core and the clad of not less than 0.020. 6. The fluorinated polymer constituting the amorphous fluororesin (A) is a polymer having a repeating unit in which a monomer (a) represented by the following formula (1) is cyclopolymerized. 5 wherein m is an integer of 05, and RRR ³ and R ⁴ each independently represent a perfluoroalkyl group having 19 carbon atoms, a chlorine atom or a fluorine atom. CF ^ CF-O-CR ^ ^2- (CR ³ R ⁴ ) -CF = CF ₅ (1) 7. The step index type plastic optical fiber according to claim 5, wherein the high refractive index agent is a fluorine-containing aromatic compound having substantially no hydrogen atom. 8. The fluoropolymer constituting the amorphous fluororesin (B) is a polymer having a repeating unit in which a monomer (b) represented by the following formula (3) is polymerized. However,; ¹¹ and R ¹² each independently represent a perfluoroalkyl group having 19 carbon atoms or a fluorine atom.

9. The step index type plastic light according to claim 56, wherein the amorphous fluororesin (B) contains a fluoroplasticizer having substantially no hydrogen atoms. 10. The core is made of an amorphous fluororesin (A) composed of a fluoropolymer having substantially no hydrogen atoms, or the amorphous fluororesin (A) containing a high-refractive-index agent; Is composed of an amorphous fluororesin (B-2) composed of a fluorine-containing polymer having a refractive index of less than 1.300, which has substantially no hydrogen atoms, and the refractive index difference between the core and the clad is at least 0.002 A step index type plastic optical fiber, characterized in that: 1 1. The fluorinated polymer constituting the amorphous fluororesin (A) is a polymer represented by the following formula (1) and having a repeating unit in which the monomer ( _a ) is cyclopolymerized. 10. The step index type plastic optical fiber described in 10. Here, m represents an integer of 0 to 5, and RR ² , R ³ and R ⁴ each independently represent a perfluoroalkyl group having 1 to 9 carbon atoms, a chlorine atom or a fluorine atom. CF ^ CF-O-CR ¹ ^-(CR ³ R ⁴ ) _m _CF = CF; (1) 12. The step index type plastic optical fiber according to claim 10 or 11, wherein the high refractive index agent is a fluorine-containing aromatic compound having substantially no hydrogen atom.  13. The fluorine-containing polymer constituting the amorphous fluororesin (B-2) has a repeating unit in which a monomer (b-1) represented by the following formula (4) is polymerized, and has a refractive index of: 13. The step-index plastic optical fiber according to claim 10, which is a fluoropolymer having a molecular weight of less than 1.3. Here, R ¹³ represents a perfluoroalkyl group having 2 to 9 carbon atoms, and ¹⁴ represents a perfluoroalkyl group having 1 to 9 carbon atoms or a fluorine atom. (Four)

14. The step index type plastic optical fiber according to claim 10, 11, 12, or 13, wherein the amorphous fluororesin (B-2) contains a fluorinated plasticizer having substantially no hydrogen atoms.  15. Amorphous fluororesin (A) whose core is composed of a fluoropolymer having a repeating unit in which the monomer (a) is represented by the following formula (1) and the monomer (a) is cyclopolymerized, or a high refractive index agent Wherein the cladding is made of a fluorine-containing polymer having a repeating unit obtained by polymerizing a monomer (b-1) represented by the following formula (4): It is made of a fluorine resin (B-3) or the amorphous fluorine resin (B-3) containing a fluorine-containing plasticizer having substantially no hydrogen atoms, and a difference in refractive index between the core and the clad is 0.020 or more. A step index type plastic optical fiber, characterized in that: However, m is an integer of 0 to 5, R ¹ R ² , R ³ and R ⁴ are each independently a perfluoroalkyl group having 1 to 9 carbon atoms, a chlorine atom or a fluorine atom, and R ¹³ is a carbon atom of 2 to 9 pel full O b alkyl group, R ¹⁴ represents a Perufuruoroaru kill group or a fluorine atom of one to 9 carbon atoms. CF 产 CF— O— CR — (CR ^{3 4} ) _m — CF-CF (1)

16. The core is made of an amorphous fluororesin (A) composed of a fluorine-containing polymer having substantially no hydrogen atoms, or the amorphous fluororesin (A) containing a high-refractive-index agent; Is composed of an amorphous fluororesin (B) composed of a fluoropolymer substantially having no hydrogen atom, or an amorphous fluororesin (B) containing a fluoroplasticizer substantially having no hydrogen atom. Characterized in that the numerical aperture (NA) is 0.415 or more, 7. Perfluro (2-pentyl-1, 3-dioxole).  18. Fluoropolymer having a repeating unit in which perfluoro (2-pentyl-13-dioxole) is superimposed as a monomer.  19. An optical member, characterized by using a fluoropolymer having a repeating unit in which perfluoro (2-pentyl-13-dioxole) is superimposed as a monomer.  20. The optical member according to claim 19, wherein the optical member is a plastic optical fiber.  21. The optical system according to claim 20, wherein a fluoropolymer having a repeating unit in which perfluoro (2-pentyl-1,3-dioxol) is polymerized as a monomer is used as a core or a clad of the plastic optical fiber. Element.