Optical resin composition and optical resin molded article

Abstract

The optical resin composition according to the present invention comprises a fluorine-containing resin and a refractive index adjusting agent. This optical resin composition satisfies either of the following (a) or (b): (a) the refractive index adjusting agent contains 95 mass% or more of linear polymer (A) containing a fluorine-containing ethylene monomer-based repeating unit with a repeating unit number of 5 and the content of linear polymer (A) in the optical resin composition is 1 mass% or more and less than 15 mass%; and (b) the refractive index adjusting agent contains 95 mass% or more of linear polymer (B) containing a fluorine-containing ethylene monomer-based repeating unit with a repeating unit number of 6 and the content of linear polymer (B) in the optical resin composition is 1 mass% or more and less than 13 mass%.

Description

[Technical Field]

[0001] The present invention relates to optical resin compositions and optical resin molded articles. [Background technology]

[0002] Fluorine-containing resins are useful substances that can be used in a wide range of fields as materials for optical components such as plastic optical fibers (hereinafter referred to as "POF") and exposure components. When fluoroine-containing resins are used as materials for optical components, optical resin compositions obtained by mixing fluoroine-containing resins with various additives such as refractive index adjusters are usually used. For example, when fluoroine-containing resins are used as core materials for refractive index distribution type POFs, in optical resin compositions in which refractive index adjusters are added to fluoroine-containing resins, the refractive index distribution is formed by diffusing the refractive index adjusters.

[0003] Many of the refractive index modifiers added to fluororesins are compounds with relatively low molecular weight. Therefore, when a refractive index modifier is mixed with a fluororesin, a problem arises regarding the compatibility between the fluororesin and the refractive index modifier, that is, the refractive index modifier is not uniformly mixed with the fluororesin. To address this, for example, Patent Document 1 proposes using at least one fluorine-containing polycyclic compound selected from perfluoro(1,3,5-triphenylbenzene) and perfluoro(1,2,4-triphenylbenzene) as a refractive index modifier added to a fluororesin. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 4682394 [Overview of the project] [Problems that the invention aims to solve]

[0005] As described above, various proposals have been made for compounds used as refractive index modifiers in order to obtain optical resin compositions in which the compatibility between the fluororesin and the refractive index modifier is improved. However, in optical resin compositions containing a fluororesin and a refractive index modifier, conventionally proposed refractive index modifiers do not have sufficient compatibility with the fluororesin, and problems such as impaired transparency still occur.

[0006] Furthermore, in recent years, high heat resistance is often required for optical components. Therefore, many fluororesins used as materials for optical components have high glass transition temperatures. Optical resin compositions containing such fluororesins with high glass transition temperatures require high temperatures in the processing process. Consequently, optical resin compositions are also required to withstand high-temperature processing, meaning that the refractive index can be adjusted to a desired range using refractive index adjusting agents.

[0007] Therefore, the present invention aims to provide an optical resin composition comprising a fluororesin and a refractive index adjuster that can be used in high-temperature processing processes and in which a decrease in transparency is suppressed by improving the compatibility between the fluororesin and the refractive index adjuster. Furthermore, the present invention also aims to provide an optical resin molded article in which the refractive index is adjusted to a desired range and has sufficient transparency. [Means for solving the problem]

[0008] An optical resin composition according to a first aspect of the present invention is an optical resin composition comprising a fluororesin and a refractive index adjusting agent, wherein the optical resin composition satisfies either (a) or (b) below: (a) The refractive index adjusting agent contains 95% by mass or more of a linear polymer (A) having repeating units based on a fluorine-containing ethylene monomer with a repeating unit number of 5, and the content of the linear polymer (A) in the optical resin composition is 1% by mass or more and less than 15% by mass. (b) The refractive index adjusting agent contains 95% by mass or more of a linear polymer (B) having 6 repeating units based on a fluorine-containing ethylene monomer, and the content of the linear polymer (B) in the optical resin composition is 1% by mass or more and less than 13% by mass.

[0009] An optical resin molded article according to a second aspect of the present invention comprises the optical resin composition according to the first aspect described above. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an optical resin composition that can be used even in high-temperature processing processes and in which the reduction in transparency is suppressed by improving the compatibility between the fluororesin and the refractive index adjusting agent. Furthermore, according to the present invention, it is also possible to provide an optical resin molded article in which the refractive index is adjusted to a desired range and has sufficient transparency. [Modes for carrying out the invention]

[0011] (Embodiment 1) Embodiments of the optical resin composition of the present invention will now be described. The optical resin composition of this embodiment comprises a fluororesin and a refractive index modifier. The optical resin composition of this embodiment satisfies either (a) or (b) below: (a) The refractive index adjusting agent contains 95% by mass or more of a linear polymer (A) having repeating units based on a fluorine-containing ethylene monomer with a repeating unit number of 5, and the content of the linear polymer (A) in the optical resin composition of this embodiment is 1% by mass or more and less than 15% by mass. (b) The refractive index adjusting agent contains 95% by mass or more of a linear polymer (B) having 6 repeating units based on a fluorine-containing ethylene monomer, and the content of the linear polymer (B) in the optical resin composition of this embodiment is 1% by mass or more and less than 13% by mass.

[0012] By satisfying either (a) or (b) above, the optical resin composition of this embodiment can achieve high transparency through improved compatibility between the fluororesin and the refractive index adjusting agent, and can also be used in high-temperature processing processes. Here, an optical resin composition that can be used in high-temperature processing processes means an optical resin composition in which the refractive index of the optical resin composition can be adjusted within a desired range by the refractive index adjusting agent, even when processed in a high-temperature processing process.

[0013] The mechanism by which the optical resin composition of this embodiment can achieve both transparency and use in high-temperature processing processes by including linear polymer (A) within the range specified in (a) above, or linear polymer (B) within the range specified in (b) above, is not clear. However, since linear polymer (A) and linear polymer (B) have a relatively small number of repeating units, it is thought that they can contribute more to improving the solubility of the refractive index modifier in the fluororesin. Furthermore, when the optical resin composition of this embodiment includes linear polymer (A) within the range specified in (a) above, or linear polymer (B) within the range specified in (b) above, it is thought that a better balance can be achieved between high solubility of the refractive index modifier in the fluororesin and suppression of volatilization of the refractive index modifier when undergoing high-temperature processing processes. Therefore, with this configuration, it is thought that high transparency can be achieved even if the content ratio of the refractive index modifier is increased, and furthermore, an optical resin composition that can be used in processing processes at even higher temperatures can be realized.

[0014] If the optical resin composition of this embodiment satisfies (a) above, that is, if the refractive index adjusting agent contained in the optical resin composition of this embodiment contains 95% by mass or more of the linear polymer (A), then the optical resin composition of this embodiment contains 1% by mass or more and less than 15% by mass of the linear polymer (A). In this case, the optical resin composition of this embodiment may contain, for example, 7% by mass or more, 8% by mass or more, or 9% by mass or more of the linear polymer (A). Furthermore, the optical resin composition of this embodiment may contain, for example, 14% by mass or less, 13% by mass or less, 12% by mass or less, or 11% by mass or less of the linear polymer (A). The upper and lower limits of the range of the content ratio of the linear polymer (A) in the optical resin composition of this embodiment may be defined by any combination selected from the above values. For example, the optical resin composition of this embodiment may contain linear polymer (A) in an amount of 1% to 14% by mass, 8% to less than 15% by mass, 8% to 14% by mass, 8% to 12% by mass, or 8% to 11% by mass. When the refractive index modifier contained in the optical resin composition of this embodiment contains 95% or more by mass of linear polymer (A), high transparency can be achieved even when the content of the refractive index modifier in the optical resin composition increases by including linear polymer (A) in the above range proportions. Furthermore, since the volatilization start temperature of the refractive index modifier can be increased while maintaining good solubility of the refractive index modifier in the fluororesin, an optical resin composition can be realized that can be used in processing processes at higher temperatures while ensuring transparency. In this case, the volatilization start temperature of the refractive index modifier can be set to, for example, 200°C or higher. In other words, by including a refractive index adjusting agent within the above range in the optical resin composition of this embodiment, the refractive index can be easily adjusted to an appropriate range without significantly reducing the heat resistance of the optical resin composition.

[0015] If the optical resin composition of this embodiment satisfies (b) above, that is, if the refractive index adjusting agent contained in the optical resin composition of this embodiment contains 95% by mass or more of the linear polymer (B), then the optical resin composition of this embodiment contains 1% by mass or more and less than 13% by mass of the linear polymer (B). In this case, the optical resin composition of this embodiment may contain, for example, 7% by mass or more of the linear polymer (B), 8% by mass or more, 9% by mass or more, or 10% by mass or more of the linear polymer (B). Furthermore, the optical resin composition of this embodiment may contain, for example, 12% by mass or less of the linear polymer (B). The upper and lower limits of the range of the content ratio of the linear polymer (B) in the optical resin composition of this embodiment may be defined by any combination selected from the above values. For example, the optical resin composition of the embodiment may contain 1% by mass or more and 12% by mass or less of the linear polymer (B), 8% by mass or more and less than 13% by mass, or 8% by mass or more and 12% by mass or less of the linear polymer (B). When the refractive index adjusting agent contained in the optical resin composition of this embodiment contains 95% by mass or more of the linear polymer (B), high transparency can be achieved even when the content of the refractive index adjusting agent in the optical resin composition increases, by including the linear polymer (B) in the above-mentioned range. Furthermore, since the volatilization start temperature of the refractive index adjusting agent can be increased while maintaining good solubility of the refractive index adjusting agent in the fluororesin, an optical resin composition can be realized that can be used in processing processes at higher temperatures while ensuring transparency. In this case, the volatilization start temperature of the refractive index adjusting agent can be set to, for example, 200°C or higher. In other words, by including the refractive index adjusting agent in the above-mentioned range in the optical resin composition of this embodiment, the refractive index can be easily adjusted to an appropriate range without significantly reducing the heat resistance of the optical resin composition.

[0016] Here, a linear polymer (A) containing repeating units based on a fluorine-containing ethylene monomer with a repeating unit number of 5 and a linear polymer (B) containing repeating units based on a fluorine-containing ethylene monomer with a repeating unit number of 6 can each be obtained, for example, by distilling a polymer of the fluorine-containing ethylene monomer and isolating the polymer for each repeating unit number. According to such a method, a polymer with the desired repeating unit number can be obtained with a purity of 95 mol% or more.

[0017] As the fluorine-containing ethylene monomer constituting the linear polymer, for example, a compound represented by the following formula (1) is used.

Chemical formula

[0018] The fluorine-containing ethylene monomer preferably does not contain a hydrogen atom. The optical resin composition in this embodiment is used for optical applications. From the viewpoint of suppressing light absorption due to the stretching energy of the C-H bond, it is desirable that the optical resin composition does not contain a C-H bond. Therefore, the fluorine-containing ethylene monomer preferably does not contain a hydrogen atom, and the H of all C-H bonds may be fluorinated.

[0019] The fluorine-containing ethylene monomer may be, for example, chlorotrifluoroethylene represented by the following formula (2).

Chemical formula

[0020] Furthermore, if the optical resin composition of this embodiment satisfies (a) above, the refractive index modifier may include a linear polymer containing repeating units based on a fluorine-containing ethylene monomer having a number of repeating units other than that of the linear polymer (A) (for example, 4, 6, and / or 7 repeating units, etc.) (for example, a chlorotrifluoroethylene oligomer with 4, 6, and / or 7 repeating units, etc.), provided that the amount is within the range of 5% by mass or less. Also, if the optical resin composition of this embodiment satisfies (b) above, the refractive index modifier may include a linear polymer containing repeating units based on a fluorine-containing ethylene monomer having a number of repeating units other than that of the linear polymer (B) (for example, 4, 5, and / or 7 repeating units, etc.) (for example, a chlorotrifluoroethylene oligomer with 4, 5, and / or 7 repeating units, etc.), provided that the amount is within the range of 5% by mass or less.

[0021] As described above, it is desirable that the optical resin composition in this embodiment does not contain CH bonds. Therefore, it is preferable that the first linear polymer and the second linear polymer are substantially hydrogen atom-free, and more preferably hydrogen atom-free. Here, it is said that the first and second linear polymers are substantially hydrogen atom-free if the hydrogen atom content in the first and second linear polymers is 1 mol% or less.

[0022] The fluororesin contained in the optical resin composition of this embodiment preferably has a glass transition temperature of 105°C or higher, more preferably 120°C or higher. Because the fluororesin has such a high glass transition temperature, the optical resin composition obtained by mixing the fluororesin with a refractive index adjuster is less affected by the decrease in glass transition temperature due to the addition of the refractive index adjuster, and can maintain a high glass transition temperature. Therefore, in this case, the optical resin composition of this embodiment can also have high heat resistance. The upper limit of the glass transition temperature of the fluororesin contained in the optical resin composition of this embodiment is not particularly limited, but for example, it is 140°C or lower.

[0023] The fluorine-containing resin contained in the optical resin composition of the present embodiment is, for example, a polymer obtained by using a fluorine-containing compound having a polymerizable double bond as a monomer. The optical resin composition in the present embodiment is used for optical applications. From the viewpoint of suppressing light absorption due to the stretching energy of C-H bonds, it is desirable that the optical resin composition does not contain C-H bonds. Therefore, the fluorine-containing resin preferably contains substantially no hydrogen atoms, and particularly preferably all H of all C-H bonds are fluorinated. That is, the fluorine-containing resin preferably contains substantially no hydrogen atoms and is fully fluorinated. That the fluorine-containing resin contains substantially no hydrogen atoms means that the content ratio of hydrogen atoms in the fluorine-containing resin is 0.1 mol% or less.

[0024] When the fluorine-containing resin is fully fluorinated, examples of the fluorine-containing compound that constitutes the fluorine-containing resin include compounds represented by the following formula (3).

Chemical formula

[0025] Specific examples of the compound represented by the above formula (3) include compounds represented by the following formulas (A) to (H).

Chemical formula

[0026] Among the compounds represented by the above formulas (A) to (H), the compound (B), that is, the fluorine-containing compound represented by the following formula (4), is preferably used as the fluorine-containing compound that constitutes the fluorine-containing resin. [ka]

[0027] A polymer using the compound represented by formula (4) above as a monomer can have a high glass transition temperature of, for example, about 110°C or higher. Therefore, by using such a fluororesin, the optical resin composition obtained by mixing the fluororesin with a refractive index adjuster can maintain a high glass transition temperature and have excellent heat resistance.

[0028] Furthermore, it is preferable to use a purified fluorine-containing compound that is free of impurities. Purification can be achieved by known methods. In particular, it is preferable that acidic components are not included among the impurities, as they affect the coloration.

[0029] The fluorine-containing compound used as a monomer may be composed of two or more compounds. That is, the fluorine-containing resin used in the optical resin composition of this embodiment may be a copolymer of multiple fluorine-containing compounds. Examples of fluorine-containing compounds used as monomers (comonomers) of the copolymer include, in addition to the fluorine-containing compounds represented by (A) to (H) above, tetrafluoroethylene, chlorotrifluoroethylene, and fluorovinyl ethers (such as perfluoropropyl vinyl ether).

[0030] The fluorine-containing resin used in the optical resin composition of this embodiment can be produced, for example, by using the fluorine-containing compounds exemplified above as monomers and polymerizing these monomers using, for example, known polymerization initiators, by known methods. Known polymerization methods can be used as polymerization methods. For example, a fluorine-containing resin can be produced by radical polymerization of the fluorine-containing compounds exemplified above by conventional methods. A fully fluorinated fluorine-containing resin can be produced by using a fully fluorinated fluorine-containing compound as a monomer and further using a polymerization initiator consisting of a fully fluorinated compound.

[0031] The optical resin composition of this embodiment can have high transparency. For example, the optical resin composition of this embodiment can achieve transparency with an internal transmittance of 99.9% or higher. The internal transmittance of the optical resin composition can be measured by, for example, the following method. The optical resin composition is sealed in a cylindrical container and heated and melted to form a cylindrical rod. The temperature during heating and melting is appropriately determined according to the melting temperature of the fluororesin contained in the optical resin composition. For example, if the fluororesin contained in the optical resin composition is a fluororesin obtained by polymerizing the fluororesin compound exemplified above as a monomer, the optical resin composition is heated and melted at, for example, 270°C. After removing irregularities by polishing the top and bottom surfaces of the obtained rod, the transmittance of the rod at a wavelength of 850 nm is measured using, for example, a U-4100 ultraviolet-visible-near-infrared spectrophotometer manufactured by Hitachi High-Tech Science. The internal transmittance is calculated by substituting the transmittances of two rods of different lengths (rods 1 and 2) into the following formula.

[0032] logτ = -(logT1 - logT2) × 10 / Δd Internal transmittance: τ T1: Transmittance (%) of Rod 1 at a wavelength of 850 nm obtained with U-4100 T2: Transmittance (%) of Rod 2 at a wavelength of 850 nm obtained with U-4100 Δd: Difference in length between rods 1 and 2 (where Δd > 0)

[0033] In the optical resin composition of this embodiment, for example, the refractive index for light with a wavelength of 850 nm may be in the range of 1.310 to 1.355.

[0034] The glass transition temperature of the optical resin composition of this embodiment is preferably 100°C or higher, and more preferably 105°C or higher. Having such a glass transition temperature enables the optical resin composition of this embodiment to achieve high heat resistance. The upper limit of the glass transition temperature of the optical resin composition of this embodiment is not particularly limited, but may be, for example, 140°C or lower.

[0035] (Embodiment 2) Embodiments of the optical resin molded article of the present invention will be described below.

[0036] The optical resin molded article of this embodiment includes the optical resin composition of Embodiment 1. As described in Embodiment 1, the optical resin composition of Embodiment 1 can have a high glass transition temperature, and furthermore, the refractive index can be adjusted to a desired range. Therefore, the optical resin molded article of this embodiment can be suitably used for optical transmission materials such as POF and optical waveguide materials, optical lenses, and prisms. The optical resin molded article of this embodiment can be suitably applied to optical transmission materials, and in particular suitably applied to POF.

[0037] When the optical resin molded body of this embodiment is a POF, it can be used, for example, as a core material for a refractive index distribution type POF in which the refractive index of the core has a distribution symmetrical to the central axis. The optical resin molded body of this embodiment contains an optical resin composition in which a refractive index adjusting agent is added to a fluororesin. Therefore, a refractive index distribution can be easily formed by diffusing the refractive index adjusting agent in the optical resin molded body.

[0038] The optical resin molded article of this embodiment can be manufactured, for example, by a manufacturing method that includes the step of heating and melting the optical resin composition of Embodiment 1 at a temperature of 50°C or higher above the glass transition temperature of the optical resin composition and molding it into a predetermined shape. It is also possible to obtain an optical resin molded article having a refractive index distribution by thermally diffusing a refractive index adjusting agent within the optical resin composition during heating. As described in Embodiment 1, the optical resin composition used in the optical resin molded article of this embodiment can be used in high-temperature processing processes and also possesses high transparency. Therefore, the optical resin molded article of this embodiment can be a molded article in which the refractive index is adjusted to a desired range and has sufficient transparency.

[0039] The specific molding method is determined appropriately according to the application. That is, known molding methods for each application can be used. For example, if the optical resin molded body of this embodiment is POF, the molded body can be produced by spinning the optical resin composition, for example, by melt extrusion, and forming it into a fiber. During this melt extrusion spinning, by diffusing a refractive index adjusting agent within the optical resin composition by heating, it is possible to produce a core of a refractive index distribution type POF in which the refractive index of the core has a distribution symmetrical to the central axis. [Examples]

[0040] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the examples shown below.

[0041] (Preparation of fluororesin) As a fluororesin, a polymer of perfluoro-4-methyl-2-methylene-1,3-dioxolane (the compound of formula (4) above) was prepared. Perfluoro-4-methyl-2-methylene-1,3-dioxolane was synthesized by first synthesizing 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, fluorinating it, and then decarboxylating the resulting carboxylate salt. Perfluorobenzoyl peroxide was used as a polymerization initiator for the polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane.

[0042] The synthesis of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, the fluorination of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane, the synthesis of perfluoro-4-methyl-2-methylene-1,3-dioxolane, and the polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane are described in detail below.

[0043] <Synthesis of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane> A 3 L three-necked flask equipped with a water-cooled condenser, a thermometer, a magnetic stirrer, and an isobaric dropping funnel were prepared. 139.4 g (1.4 mol total) of a mixture of 2-chloro-1-propanol and 1-chloro-2-propanol was placed in the flask. The flask was cooled to 0°C, and methyl trifluoropyruvate was slowly added, and the mixture was stirred for a further 2 hours. 100 mL of dimethyl sulfoxide (DMSO) and 194 g of potassium carbonate were added over 1 hour, and the mixture was stirred for a further 8 hours to obtain the reaction mixture. This reaction mixture was mixed with 1 L of water, the aqueous phase was separated, and this was further extracted with dichloromethylene. The dichloromethylene solution was then mixed with the organic reaction mixture phase, and the solution was dried over magnesium sulfate. After removing the solvent, 245.5 g of crude product was obtained. The crude product was fractionated under reduced pressure (12 Torr) to obtain 230.9 g of purified 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane. The boiling point of the purified product was 77-78°C, and the yield was 77%. The identity of the obtained purified product as 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane was confirmed by 1H NMR and 19 Confirmed by FNMR.

[0044] HNMR(ppm):4.2-4.6,3.8-3.6(CHCH2,muliplet,3H),3.85-3.88(COOCH3,multiplet,3H),1.36-1.43(CCH3,multiplet,3H) 19 FNMR (ppm): -81.3 (CF3, s, 3F)

[0045] <Fluorination of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane> 4 L of 1,1,2-trichlorotrifluoroethane was poured into a 10 L stirred reactor. Nitrogen was flowed into the reactor at a flow rate of 1340 cc / min and fluorine at a flow rate of 580 cc / min to create a nitrogen / fluorine atmosphere. After 5 minutes, 290 g of the previously prepared 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane was dissolved in 750 mL of 1,1,2-trichlorotrifluoroethane solution, and this solution was added to the reactor at a rate of 0.5 ml / min. The reactor was cooled to 0°C. After adding all of the dioxolane over 24 hours, the flow of fluorine gas was stopped. After purging with nitrogen gas, potassium hydroxide aqueous solution was added until the mixture became weakly alkaline.

[0046] After removing volatile substances under reduced pressure, the reaction vessel was cooled, and then dried under reduced pressure at 70°C for 48 hours to obtain a solid reaction product. The solid reaction product was dissolved in 500 mL of water, and excess hydrochloric acid was added to separate it into an organic phase and an aqueous phase. The organic phase was separated and distilled under reduced pressure to obtain perfluoro-2,4-dimethyl-1,3-dioxolane-2-carboxylic acid. The boiling point of the main distillate was 103°C–106°C / 100 mmHg. The yield of fluorination was 85%.

[0047] <Synthesis of perfluoro-4-methyl-2-methylene-1,3-dioxolane> The above distillate was neutralized with an aqueous potassium hydroxide solution to obtain potassium-1,3-dioxolane perfluoro-2,4-dimethyl-2-carboxylate. This potassium salt was vacuum-dried at 70°C for 1 day. The salt was decomposed at 250°C to 280°C under a nitrogen or argon atmosphere. It was condensed in a refrigeration trap cooled to -78°C to obtain perfluoro-4-methyl-2-methylene-1,3-dioxolane in 82% yield. The boiling point of the product was 45°C / 760 mmHg. 19 The product was identified using FNMR and GC-MS.

[0048] 19 FNMR:-84ppm(3F,CF3),-129ppm(2F,=CF2) GC-MS:m / e244(Molecular ion)225,197,169,150,131,100,75,50.

[0049] <Polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane> 100 g of perfluoro-4-methyl-2-methylene-1,3-dioxolane obtained by the above method and 1 g of perfluorobenzoyl peroxide were sealed in a glass tube. After the oxygen in the system was removed from this glass tube by freeze-degassing, argon was refilled and the tube was heated at 50°C for several hours. The contents became solid, but when heated further at 70°C overnight, a 100 g transparent rod-shaped substance was obtained.

[0050] The obtained transparent rod-shaped material was dissolved in Fluorinert FC-75 (manufactured by Sumitomo 3M), and the resulting solution was poured onto a glass plate to obtain a thin film of polymer. The glass transition temperature of the obtained polymer was 117°C, and it was completely amorphous. The transparent rod-shaped material was dissolved in hexafluorobenzene, and the product was purified by adding chloroform to precipitate it. The glass transition temperature of the purified polymer was approximately 135°C.

[0051] (Refractive index adjusting agent) For the refractive index modifier, an oligomer with chlorotrifluoroethylene as the monomer was used. Specifically, Daifloil #10 (manufactured by Daikin Industries, Ltd.) was prepared, and oligomers with a predetermined number of repeating units were isolated by distillation. In this example, oligomers with 4, 5, 6, and 7 repeating units were isolated. In this example, Daifloil #10 (manufactured by Daikin Industries, Ltd.) was used as the polymer of the fluorine-containing ethylene monomer, and oligomers of the fluorine-containing ethylene monomer having a predetermined number of repeating units were isolated by distillation, but the polymer used is not limited to this. Examples of polymers that can be used include, for example, Daifloil #20 (manufactured by Daikin Industries, Ltd.), Halocarbon 700 (manufactured by Genesee Scientific), Halocarbon 27 (manufactured by Genesee Scientific), Daifloil #50 (manufactured by Daikin Industries, Ltd.), and Daifloil #100 (manufactured by Daikin Industries, Ltd.).

[0052] (Number of repeating units in the polymer of the refractive index adjusting agent) Using a gas chromatograph-time-of-flight mass spectrometer (GC / TOFMS), the purity of the polymer for each refractive index modifier was analyzed for each repeating unit count. All were confirmed to have a purity of 95 mol% or higher.

[0053] (Optical resin composition) The optical resin compositions of Examples 1 to 14 and Comparative Examples 1 to 10, as described in Table 1, were prepared by melt-mixing a fluororesin and a refractive index modifier at 250°C. As the fluororesin, a polymer of perfluoro-4-methyl-2-methylene-1,3-dioxolane, prepared by the above method, was used. The refractive index modifiers used in each example and comparative example are shown in Table 1.

[0054] (Ratio of refractive index adjusting agent in optical resin composition) The content ratio of each refractive index modifier in the optical resin composition was analyzed using ion chromatography (IC). The results are shown in Table 1.

[0055] (Volatility start temperature) Approximately 10 mg of each optical resin composition listed in Table 1 was sampled and subjected to thermogravimetric analysis (TGA). A Discovery TGA manufactured by TA Instruments was used as the analytical instrument. The atmospheric gas was N2 (25 ml / min). The container was made of platinum. The temperature range was from room temperature to 1000°C, and the heating rate was 10°C / min. From the obtained temperature-weight curve, the extrapolation weight loss onset temperature (the point where the tangent line to the weight loss slope line intersects with the 100% baseline) was defined as the volatilization onset temperature. The evaluation criteria for volatility were as follows. The results are shown in Table 1. A: Volatilization start temperature ≥ 200℃ B: 200℃ > Volatilization start temperature > 180℃ C: Volatilization start temperature ≤ 180℃

[0056] (transparency) The optical resin composition was visually determined to be either colorless and transparent or cloudy. The criteria for evaluating transparency were as follows. The results are shown in Table 1. A:Transparent B: Partially cloudy C: Cloudy

[0057] (Heat resistance of optical resin compositions) The glass transition temperature (Tg) was measured for each optical resin composition listed in Table 1. The measurement conditions for the glass transition temperature (Tg) were as follows: Approximately 5 mg of the optical resin composition was taken, placed in an aluminum container, and differential scanning calorimetry (DSC measurement) was performed. A TA Instruments Q-2000 was used as the apparatus. The temperature program was -80°C → 200°C → -80°C → 200°C, the measurement rate was 10°C / min, and the ambient gas was N2 (50 ml / min). The evaluation criteria for heat resistance were as follows. The results are shown in Table 1. A: Tg ≥ 105℃ B: 105℃ > Tg ≥ 100℃ C:Tg < 100℃

[0058] (Difference in refractive index of optical resin composition) The refractive index of each optical resin composition listed in Table 1 was measured. Approximately 500 mg of each optical resin composition was weighed out and a film with a thickness of approximately 100 μm was formed by heating and pressing at a temperature of 180-250°C and a pressure of 20 MPa. The refractive index of the obtained film for light with a wavelength of 848 nm was measured using a prism coupler. Similarly, the refractive index of the fluororesin alone, without refractive index adjusting agents, was measured, and the difference was taken as the refractive index difference. The evaluation criteria for the refractive index difference were as follows. The results are shown in Table 1. A: Refractive index difference ≥ 0.0400 B: 0.0400 > Refractive index difference ≥ 0.0225 C: Refractive index difference < 0.0225

[0059] [Table 1]

[0060] As shown in Table 1, the results from Examples 1 to 6 and Comparative Example 1 indicate that when the number of repeating units of the linear polymer used as a refractive index modifier was 6, i.e., when linear polymer (B) was used as a refractive index modifier, transparency, heat resistance, and volatilization onset temperature were all good when the content of linear polymer (B) in the optical resin composition was less than 13% by mass. In particular, when the content of linear polymer (B) in the optical resin composition was 8% by mass or more and less than 13% by mass, in addition to good transparency, heat resistance, and volatilization onset temperature, a large refractive index difference was also obtained. That is, in this case, in addition to excellent transparency, heat resistance, and volatilization onset temperature, it was also found that the refractive index could be easily adjusted within an appropriate range by the refractive index modifier.

[0061] As shown in Table 1, the results from Examples 7-14 and Comparative Example 2 indicate that when the linear polymer used as a refractive index modifier has 5 repeating units, i.e., when linear polymer (A) is used as a refractive index modifier, excellent transparency can be achieved when the content of linear polymer (A) in the optical resin composition is less than 15% by mass, and the heat resistance and volatilization onset temperature are also within a range that poses no practical problems. In particular, when the content of linear polymer (A) in the optical resin composition is 8% by mass or more and 12% by mass or less, even better heat resistance can be achieved, and a larger refractive index difference can also be obtained. That is, in this case, excellent transparency and heat resistance can be obtained, and it was also found that the refractive index can be easily adjusted within an appropriate range by the refractive index modifier. Furthermore, when the content of linear polymer (A) in the optical resin composition is 8% by mass or more and 11% by mass or less, the volatilization onset temperature is also good, and all aspects of transparency, heat resistance, refractive index difference, and volatilization onset temperature are excellent.

[0062] When the linear polymer used as a refractive index modifier had 4 repeating units, a low volatilization start temperature was observed even when the linear polymer content in the optical resin composition was as low as 8 parts by mass.

[0063] When the linear polymer used as a refractive index modifier had 7 repeating units, even when the content of the linear polymer in the optical resin composition was as low as 8 parts by mass, transparency decreased and cloudiness was observed.

[0064] The optical resin compositions shown in the examples in Table 1, which have a volatilization onset temperature of 200°C or higher, have been confirmed from the temperature-weight curves obtained by TGA analysis to not completely volatilize even above 250°C. Therefore, the optical resin compositions shown in the examples can be used in processing processes, for example, at around 250°C, and it is determined that they are fully usable, as it is possible to adjust the refractive index to the desired range.

[0065] From these results, it was confirmed that the optical resin composition of the present invention can be used even in high-temperature processing processes and that a decrease in transparency can be suppressed. [Industrial applicability]

[0066] The optical resin composition of the present invention can be used, for example, as a material for optical components that require high transparency and are manufactured by high-temperature processing processes, and is particularly suitable as a core material for POF.

Claims

1. Fluorine-containing resin and Refractive index adjusting agent, An optical resin composition comprising, The optical resin composition satisfies either (a) or (b) below: (a) The refractive index adjusting agent contains 95% by mass or more of a linear polymer (A) having repeating units based on a fluorine-containing ethylene monomer with a repeating unit number of 5, and the content of the linear polymer (A) in the optical resin composition is 1% by mass or more and less than 15% by mass. (b) The refractive index adjusting agent contains 95% by mass or more of a linear polymer (B) having 6 repeating units based on a fluorine-containing ethylene monomer, and the content of the linear polymer (B) in the optical resin composition is 1% by mass or more and less than 13% by mass. Optical resin composition.

2. The aforementioned fluorine-containing ethylene monomer is represented by the following formula (1): The optical resin composition according to claim 1. 【Chemistry 1】 (In formula (1), R 1 represents a fluorine atom, R 2 , R 3 , and R 4 Each of these independently represents a fluorine atom, a halogen atom, or a hydrogen atom.

3. The aforementioned fluorine-containing ethylene monomer does not contain hydrogen atoms. The optical resin composition according to claim 2.

4. The aforementioned fluorine-containing ethylene monomer is represented by the following formula (2): The optical resin composition according to claim 2 or 3. 【Chemistry 2】

5. The glass transition temperature of the fluororesin is in the range of 105°C to 140°C. The optical resin composition according to any one of claims 1 to 4.

6. The aforementioned fluororesin is substantially free of hydrogen atoms and is totally fluorinated. The optical resin composition according to any one of claims 1 to 5.

7. The aforementioned fluorine-containing resin is a polymer of a fluorine-containing compound represented by the following formula (3): The optical resin composition according to claim 6. 【Transformation 3】 (In formula (3), R ff 1 to R ff 4 each independently represents a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms, or a perfluoroalkyl ether group having 1 to 7 carbon atoms. R ff 1 and R ff 2 may be linked to form a ring.)

8. The fluorine-containing compound is a polymer of a fluorine-containing compound represented by the following formula (4): The optical resin composition according to claim 7. 【Chemistry 4】

9. The optical resin composition according to any one of claims 1 to 8, wherein the glass transition temperature of the optical resin composition is in the range of 105°C to 140°C.

10. An optical resin molded article comprising the optical resin composition according to any one of claims 1 to 9.

11. It is an optical transmission medium, The optical resin molded article according to claim 10.

12. The optical transmission body is a plastic optical fiber. The optical resin molded article according to claim 11.

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