JP2006199826A - Transparent resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent resin composition which can vary a refractive index in a broad range and can be used as transparent materials for various optical use excellent in transparency and heat-resistance. <P>SOLUTION: The transparent resin composition is obtained by polymerizing a mixture comprising 25-75 mass% of a polymer component (A) having methyl methacrylate as a main component and 75-25 mass% of a monomer component (B) which produces a polymer having a higher refractive index than that of the polymer component (A), wherein the refractive index can be adjusted by varying a mixing ratio of the polymer component (A) and the monomer component (B) within the above range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a transparent optical article having a desired refractive index and excellent transparency and heat resistance by uniformly dispersing two types of polymers having different refractive indexes. The present invention relates to a functional resin composition.

  With the rapid progress of electronic devices such as optical devices and semiconductor lasers and optical communication systems, various optical components have been developed. As optical components, research on optical fibers for optical communication systems, gradient index lenses and optical devices has been actively conducted, and these optical components will play an important role in the future in the optoelectronic field. is expected. In the field of such optical components, a transparent material capable of adjusting the refractive index to a desired one is expected.

  The optical fiber is composed of a high index core and a low index clad (sheath), which is a step index type that reflects and transfers light at the core-sheath interface, and from the center to the periphery of the optical fiber cross-section system. For example, silica-based optical fibers, multicomponent glass-based optical fibers, and plastic-based optical fibers have been developed and commercialized. Of these optical fibers, silica-based optical fibers and multi-component glass-based optical fibers are often used for long-distance transmission and have a characteristic of having good optical transmission characteristics, but they are difficult to be fragile. There is. On the other hand, plastic optical fibers are used for short-distance transmission because optical transmission characteristics are inferior to glass optical fibers, but they can be large-diameter optical fibers and have excellent processability. . In recent years, a plastic clad optical fiber having a plastic clad on a quartz or glass core has been regarded as promising as having the characteristics of an optical fiber for medium distance transmission.

  For the core material of the above plastic optical fiber, polymethyl methacrylate resin, polystyrene resin, polycarbonate resin, cyclic polyolefin resin, poly-4-methylpentene-1, deuterated polymethyl methacrylate and deuterated A transparent and high refractive index organic polymer material typified by polystyrene or the like is used. In addition, silicon-based resins and fluorine-based resins having a lower refractive index are often used for the cladding material. Particularly, fluorine-based resins are frequently used from the viewpoint of good weather resistance in addition to low refractive index. (Patent Document 1). However, the fluororesin used as a cladding material is used as a single polymer material such as a (meth) acrylic acid fluorinated alkyl ester resin or a vinylidene fluoride copolymer. For this purpose, attempts have been made to blend these resins with other resins. However, these fluororesins have poor compatibility with other resins and become opaque by blending the resins. For this reason, modification improvement of these resins cannot be handled by blending with other resins, and resin compositions in which these resins are blended with other resins are applied to optical fiber cladding materials and optical devices. There are few known examples.

  An example of a mixture of a polymethyl methacrylate resin and a resin excellent in compatibility with a polystyrene resin is disclosed in Japanese Patent Application Laid-Open No. 62-57449 (Patent Document 2) and the like as being suitable for a wide range of applications in the optical field. Although described, it is difficult to adjust the refractive index to a desired value, and it is difficult to obtain a molded article having sufficient transparency, heat resistance, and mechanical strength.

As a transparent resin composition, a blend of a vinylidene fluoride resin and a vinyl ester copolymer is known, and the production method thereof includes a method of kneading each polymer in a molten state, This is because the solvent is removed after mixing the polymer dissolved in the common solvent. Such a blend system of vinylidene fluoride resin and vinyl ester copolymer has a drawback that the range in which the refractive index can be adjusted is narrow, and the refractive index can be adjusted in a wider range and the resin system having excellent transparency can be used. Development has been promoted, and various blends of polymers having different refractive indexes and methods for producing blends have been proposed (Patent Document 3). However, even in these resin blends, the heat resistance is higher than the range in which the refractive index can be controlled and the heat resistance (in comparison with the previous blend system of vinylidene fluoride resin and vinyl ester copolymer) The glass transition temperature) was not sufficient. Examples of resin mixtures having excellent heat resistance are disclosed in JP-A-06-208028 (Patent Document 4), JP-A-06-256433 (Patent Document 5) and the like. The transition temperature is about 130 ° C., and further improvement in heat resistance is desired.
JP-A-53-60242 JP 62-57449 A Japanese Patent Application No. 1-281725 Japanese Patent Laid-Open No. 06-208028 Japanese Patent Laid-Open No. 06-256433

  The problem of the present invention is that the refractive index can be changed in a wide range, and a molded article excellent in transparency and heat resistance can be obtained. The step index type optical fiber, the core material of the graded index type optical fiber, An object of the present invention is to provide a transparent resin composition that can be used as a clad material and various optical transparent materials such as optical lenses.

  As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, a monomer comprising a specific lactone compound that forms a polymer having a refractive index higher than that of a polymer mainly composed of methyl methacrylate. A resin composition obtained by polymerizing a body component in the presence of a polymer mainly composed of methyl methacrylate and changing the proportion of the abundance is a mixture having an internetwork polymer structure of two types of polymers. It was found that the refractive index of the resin composition changed with the change in the mixing ratio of the monomer component and the polymer component. A resin composition having a desired refractive index is obtained by adjusting the mixing ratio of the monomer component and the polymer component, and a molded article having excellent transparency and heat resistance is molded from the obtained resin composition. The present inventors have obtained knowledge that the present invention can be performed, and have come to make the present invention based on such knowledge.

  That is, the present invention relates to a polymer component (A) mainly composed of methyl methacrylate and a general formula (1).

(In the formula, R ¹ represents a methyl group, an ethyl group or a propyl group, and R ² and R ³ independently represent a hydrogen atom, an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms. Represents a phenyl group which may be unsubstituted or substituted with an alkyl group, or a cyclohexyl group which may be unsubstituted or substituted with a fluorine atom, and R ² and R ³ are bonded together. A polymer component comprising a lactone compound represented by the following formula: a 5- or 6-membered ring may be formed including carbon atoms, and the 5- or 6-membered ring may be substituted with a fluorine atom. A transparent resin composition obtained by polymerizing a mixture containing a monomer component (B) that produces a polymer having a higher refractive index than (A),
A monomer component (B) containing, as a main component, a lactone compound represented by the general formula (1) in a range of 25 to 75% by mass of the polymer component (A) containing methyl methacrylate as a main component in the mixture. The present invention relates to a transparent resin composition characterized in that the refractive index can be adjusted by changing the mixing ratio in the range of 75 to 25% by mass.

  The transparent resin composition of the present invention can change the refractive index in a wide range, and can obtain a molded article excellent in transparency and heat resistance. The step index type optical fiber and graded index type light can be obtained. It can be used as a fiber core material, a clad material, and various optical transparent materials such as an optical lens.

  The transparent resin composition of the present invention comprises 25 to 75% by mass of a polymer component (A) mainly composed of methyl methacrylate, and a general formula (1).

(In the formula, R ¹ represents a methyl group, an ethyl group or a propyl group, and R ² and R ³ independently represent a hydrogen atom, an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms. Represents a phenyl group which may be unsubstituted or substituted with an alkyl group, or a cyclohexyl group which may be unsubstituted or substituted with a fluorine atom, and R ² and R ³ are bonded together. A 5- or 6-membered ring including a carbon atom may be formed, and the 5- or 6-membered ring may be substituted with a fluorine atom), and a polymer component (A A transparent resin composition obtained by polymerizing a mixture of 75 to 25% by mass of the monomer component (B) that produces a polymer having a higher refractive index than the polymer component (A) and Mixing of the monomer component (B) If the case that the adjustable refractive index by changing within the range described above, it is not particularly limited.

The polymer component (A) mainly composed of methyl methacrylate used in the transparent resin composition of the present invention may contain a homopolymer of methyl methacrylate, or methyl methacrylate and other monomers. And a copolymer thereof. Examples of monomers that form a copolymer of methyl methacrylate include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, and (meth) acrylic. Tert-butyl acid, n-butyl (meth) acrylate, 2-hydroxy (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 2- (n-butoxyethyl) (meth) acrylate, (meth) Glycidyl acrylate, 2-methylglycidyl (meth) acrylate, other (meth) acrylic acid alkyl esters,
(Meth) acrylic acid fluoromethyl, (meth) acrylic acid fluoroethyl, (meth) acrylic acid 2,2,2-trifluoroethyl, (meth) acrylic acid 2,2,3,3-tetrafluoropropyl, 2, 2,3,3,3-pentafluoropropyl methacrylate, (meth) acrylic acid 2,2,3,3,4,4-hexafluoro, (meth) acrylic acid 2,2,3,3,4,4,4 5,5-octafluoropentyl, (meth) acrylic acid 1,1,2,2-tetrahydroperfluorooctyl, (meth) acrylic acid 1,1,2,2-tetrahydroperfluorodecanyl, (meth) Fluorinated (meth) acrylic acid alkyl esters such as hexafluoroneopentyl acrylate,
Benzyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, Phenyl (meth) acrylate, benzyl (meth) acrylate, tricyclo [5.2.1.0 ^2,6 ] -dec-8-yl methacrylate, other alicyclic (meth) acrylic acids,
Aromatic vinyl compounds such as α-substituted styrene such as styrene, α-methylstyrene, α-ethylstyrene, and substituted styrene such as fluorostyrene and methylstyrene.

  In the case where the copolymer of these monomers and methyl methacrylate is used as the polymer component (A), when the copolymer has a lower refractive index than the homopolymer of methyl methacrylate, Although the range of the refractive index that can be adjusted is expanded, the compatibility between the polymer component (A) and the monomer component (B) tends to deteriorate, that is, obtained from the transparent resin composition of the present invention. It is necessary to determine the type and compounding ratio of the monomer that forms the copolymer of methyl methacrylate, noting that the transparency of the molded product tends to decrease and does not impair the transparency of the molded product. . In addition, when the copolymer has a higher refractive index than the homopolymer of methyl methacrylate, the range of the refractive index that can be adjusted in the transparent resin composition of the present invention is reduced, but the polymer component (A) and the monomer The compatibility with the component (B) tends to improve, that is, the transparency of the molded product obtained from the transparent resin composition of the present invention tends to increase. Therefore, when a copolymer of methyl methacrylate is used as the polymer component (A), it is necessary to select the type and amount of the monomer to be used in consideration of the refractive index and compatibility.

  The molecular weight of the polymer in the polymer component (A) containing methyl methacrylate as a main component is not particularly limited. However, when the molecular weight is too high, the molding processability is lowered or too low. Has a disadvantage that a sufficient mechanical strength cannot be obtained. Therefore, the molecular weight determined by GPC polystyrene conversion is preferably in the range of 10,000 to 300,000 in terms of weight average molecular weight. In addition, a polymer containing methyl methacrylate as a main component can be obtained by polymerizing methyl methacrylate alone as a monomer, or methyl methacrylate and one or more of the above monomers by a known method. Can do.

  General formula (1) used for the transparent resin composition of the present invention

As the monomer component (B) mainly composed of a lactone compound represented by the formula (1), any monomer component that produces a polymer having a higher refractive index than that of the polymer component (A) can be used. Is not to be done.

The lactone compound represented by the general formula (1) contained as a main component in the monomer component (B) is a derivative of α-methylene-γ-butyrolactone, and methylene at the α-position of α-methylene-γ-butyrolactone. Is a lactone compound having a 5-membered ring structure having a substituent R ¹ at the β-position, and structurally, the α-position carbon of methyl methacrylate is bonded to the carbon of the methyl group that is ester-bonded. , Has a circular structure. When the lactone compound represented by the general formula (1) has the substituent R ¹ at the β-position, the rotational movement of the main chain is restricted in the polymer of this compound. For this reason, other structures of lactone compounds having no substituent at the β-position and having a substituent only at the γ-position, such as α-methylene-γ-methyl-γ-butyrolactone, α-methylene-γ, γ-dimethyl Compared with the case of using -γ-butyrolactone or the like, the heat resistance (glass transition temperature) can be remarkably improved in the transparent resin composition of the present invention. In order to reduce the heat resistance of the resulting (co) polymer as the β-position substituent R ¹ becomes bulky, the substituent R ¹ is a methyl group having 1 to 3 carbon atoms, ethyl Group or propyl group.

Such substituent R ¹ has the general formula (2)

(Wherein, R ¹ to R ³ of the general formula (showing the same as R ¹ to R ³ in 1).) And S-isomers isomer represented by the general formula (3)

(Wherein, R ¹ to R ³ of the general formula (1) in R ¹ to R ³ and. That shows the same thing) configuration of the lactone compound represented by the general formula (1) as R-form isomers represented by It preferably constitutes an isomer. The lactone compound represented by the general formula (1) is a mixture of the (S) isomer represented by the general formula (2) and the (R) isomer represented by the general formula (3). In the transparent resin composition of the present invention, the transparency required for an optical transparent material can be provided. Lactone compounds having other structures that do not have a substituent structure at the β position and have a substituent only at the γ position (for example, α-methylene-γ-methyl-γ-butyrolactone, α-methylene-γ, γ-dimethyl- When γ-butyrolactone or the like is used, the resin composition tends to decrease in transparency, but the lactone compound represented by the general formula (1) is represented by the general formula (2) (S ) Isomer and (R) isomer represented by the general formula (3) have a mass ratio in the range of 30 to 70 to 70 to 30, more preferably in the range of 45 to 55 to 55 to 45. In the case of a mixture, in the transparent resin composition of the present invention, heat resistance can be improved while maintaining extremely high transparency.

In addition, the substituents R ² and R ³ in the γ-position of the lactone compound represented by the general formula (1) need to be not bulky because the heat resistance of the polymer is lowered when the bulk is increased. A hydrogen atom, an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms which may be substituted with a fluorine atom, an unsubstituted or substituted phenyl group with an alkyl group, or an unsubstituted or substituted with a fluorine atom. A cyclohexyl group which may be substituted, R ² and R ³ may be combined with each other to form a 5- or 6-membered ring including the carbon atom to which they are bonded; It may be substituted with an atom. Such an alkyl group having 1 to 12 carbon atoms may be linear or branched, and a carbon atom in the main chain may be substituted with a sulfur atom, an oxygen atom, a nitrogen atom or a phosphorus atom. The alkyl group having 1 to 12 carbon atoms represented by the substituents R ² and R ³ is C _n F _m H _{2n + 1-m} substituted with a fluorine atom (n is a natural number of 1 to 12, m is a natural number of 2n + 1 or less) It may be represented by a certain). The phenyl group represented by the substituents R ² and R ³ may have a lower alkyl group such as a methyl group, an ethyl group, or a propyl group as a substituent. In addition, as the 5- or 6-membered ring formed by including the carbon atoms to which the substituents R ² and R ³ are bonded together, cyclopentane, cyclohexane, and hydrogen atoms thereof are substituted with fluorine atoms. Can be mentioned. The number of fluorine atoms substituting for hydrogen atoms in the alkyl groups, cyclohexyl groups and cyclic groups represented by the substituents R ² and R ³ are not limited in terms of the number and bonding position.

Specific examples of the lactone compound represented by the general formula (1) include α-methylene-β-methyl-γ-methyl-γ-butyrolactone (βMγMBL),
α-methylene-β-methyl-γ-dimethyl-γ-butyrolactone (βMγDMBL),
α-methylene-β-methyl-γ-ethyl-γ-butyrolactone (βMγEBL),
α-methylene-β-methyl-γ-propyl-γ-butyrolactone (βMγPBL),
α-methylene-β-methyl-γ-cyclohexyl-γ-butyrolactone (βMγCHBL),
α-methylene-β-ethyl-γ-methyl-γ-butyrolactone (βEγMBL),
α-methylene-β-ethyl-γ, γ-dimethyl-γ-butyrolactone (βEγDMBL),
α-methylene-β-ethyl-γ-ethyl-γ-butyrolactone (βEγEBL),
α-methylene-β-ethyl-γ-propyl-γ-butyrolactone (βEγPBL),
α-methylene-β-ethyl-γ-cyclohexyl-γ-butyrolactone (βEγCHBL),
Etc. In particular, in the case of an application that requires very high optical transparency, such as a clad material or a core material of a step index type optical fiber, and further a graded index type optical fiber material, both R ₂ and R ₃ are A hydrogen atom is preferable, and as such a compound, specifically,
α-methylene-β-methyl-γ-butyrolactone (βMBL),
α-methylene-β-ethyl-γ-butyrolactone (βEBL),
α-methylene-β-propyl-γ-butyrolactone (βPBL)
Is mentioned. Of these, βMBL is particularly preferred because it is excellent in the effect of improving the glass transition temperature in a small amount.

Specific examples of the monomer copolymerizable with the lactone compound contained in the monomer component (B) having the lactone compound represented by the general formula (1) as a main component include (meth) Methyl acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, tert-butyl (meth) acrylate, n-butyl (meth) acrylate, other (meth) Acrylic acid alkyl esters, etc.
Benzyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl cyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, (Meth) acrylic acid phenyl, (meth) acrylic acid benzyl, methacrylic acid tricyclo [5.2.1.0 ^2,6 ] -dec-8-yl, other alicyclic (meth) acrylic acid,
Aromatic vinyl compounds such as α-substituted styrene such as styrene, α-methylstyrene and α-ethylstyrene, and substituted styrene such as fluorostyrene and methylstyrene.
Also, fluoromethyl (meth) acrylate, fluoroethyl (meth) acrylate, trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, 2,2,3, 3,3-pentafluoropropyl methacrylate, (meth) acrylic acid 2,2,3,3,4,4,5,5-octafluoropentyl, (meth) acrylic acid 1,1,2,2-tetrahydroper Fluorinated (meth) acrylic acid alkyl esters such as fluorooctyl, 1,1,2,2-tetrahydroperfluorodecanyl (meth) acrylate, and hexafluoroneopentyl (meth) acrylate are also monomer components. Any polymer can be used as long as the polymer obtained from (B) has a higher refractive index than the polymer component (A).

  The molecular weight of the polymer obtained by polymerizing the monomer component (B) mainly composed of the lactone compound represented by the general formula (1) is not particularly limited, but is too high. However, if the molding processability is lowered or is too low, a sufficient mechanical strength cannot be obtained. Therefore, the molecular weight determined by GPC polystyrene conversion is 10,000 to 10,000 in terms of weight average molecular weight. A range of 300,000 is preferred.

  The content of the lactone compound in the monomer component (B) having the lactone compound represented by the general formula (1) as a main component is preferably in the range of 10 to 78% by mass, more preferably. Is in the range of 20 to 50% by mass, and the content of the monomer copolymerizable with the lactone compound is preferably in the range of 90 to 22% by mass, more preferably in the range of 50 to 80% by mass. . If the content of the lactone compound is in the range of 10 to 78% by mass, the compatibility between the monomer component (B) and the polymer component (A) is not impaired, and the content of the lactone compound is 20 to 50 mass. If it is in the range of%, this effect can be obtained more remarkably.

  Of the polymer component (A) in the mixture containing the polymer component (A) mainly composed of methyl methacrylate and the monomer component (B) mainly composed of the lactone compound represented by the general formula (1) The content is in the range of 25 to 75% by mass, and the content of the monomer component (B) is in the range of 75 to 25% by mass. If content of each component in a mixture is this range, it can mix uniformly, without impairing compatibility, and generation | occurrence | production of whitening can be suppressed in the transparent resin composition of this invention obtained. The transparent resin composition of the present invention obtained by polymerizing this mixture has an internetwork polymer structure and has excellent transparency. And in the transparent resin composition of this invention obtained by changing the mixing ratio of each component in the mixture of a polymer component (A) and a monomer component (B) in the said range, a refractive index is adjusted. Is possible.

  Further, such a mixture of the polymer component (A) and the monomer component (B) may contain a substance having characteristics according to the purpose within a range not impairing the functions of these components. . Examples of such substances include colorants such as dyes and pigments, various antioxidants, plasticizers, mold release agents, light stabilizers such as ultraviolet absorbers, and the like.

  As a method of polymerizing a mixture containing the polymer component (A) having methyl methacrylate as a main component and the monomer component (B) having a lactone compound represented by the general formula (1) as a main component, Any method may be used, but radical polymerization is preferred. Preferred examples of such radical polymerization include thermal polymerization methods such as solution, block, suspension, and emulsification, and photopolymerization methods. Bulk polymerization and solution polymerization are preferable from the viewpoint that the obtained (co) polymer has high purity and is suitable for optically transparent materials and optical fiber core materials. On the other hand, since the photopolymerization method has a high polymerization rate, a decrease in transparency due to phase separation between the polymer of the polymer component (A) and the monomer component (B) is suppressed, and transparency is not impaired. The range of the blend ratio of the polymer component (A) and the monomer component (B) for changing the refractive index and the range of the composition of the monomer component (B) may be wider than those of the thermal polymerization method. This is preferable for the production of the transparent resin composition of the present invention.

  The case where the transparent resin composition of the present invention is produced by polymerizing a mixture of the polymer component (A) and the monomer component (B) by a bulk polymerization method will be described. Into the mixture of the polymer component (A) mainly composed of methyl methacrylate and the monomer component (B) mainly composed of the lactone compound represented by the general formula (1), a polymerization initiator and necessary Mix chain transfer agent accordingly. This mixture is held at a predetermined temperature for a certain period of time to complete the polymerization, and the resulting bulk polymer is pulverized and degassed and extruded to leave the remaining monomer, polymerization initiator, chain transfer agent, etc. Can be removed to obtain the resin composition of the present invention having an internetwork polymer structure. The polymerization initiator is not particularly limited as long as it does not adversely influence side reactions or coloring during the polymerization, and may be arbitrarily selected according to the polymerization mode, polymerization temperature, polymerization rate, and polymerization time. Can do. Specifically, 2,2′-azobis (2,4,4-trimethylpentane) (trade name: VR-110, manufactured by Wako Pure Chemical Industries, Ltd.), 2,2′-azobis (isobutyronitrile), 1 , 1'-azobis (cyclohexanecarbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate (trade name: V-601, manufactured by Wako Pure Chemical Industries, Ltd.) Azo initiators such as benzoyl peroxide, lauryl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butylperoxy 2-ethylhexanoate, 1,1-di-t -Peroxide initiators such as butylperoxy-2-methylcyclohexane and the like can be mentioned, and these can be used alone or in combination of two or more. Of these, azo initiators are preferred because of the small effect of heat-colored polymers, and dimethyl 2,2′-azobisisobutyrate (trade name: V-601, manufactured by Wako Pure Chemical Industries, Ltd.) is particularly preferred. The usage-amount of these polymerization initiators can be made into the range of 0.001-3 mass parts, for example with respect to 100 mass parts of said monomer components (B).

  A chain transfer agent may be used for the purpose of adjusting the molecular weight in the bulk polymerization. The chain transfer agent is not particularly limited as long as it does not adversely influence side reactions or coloring during polymerization, and can be arbitrarily selected for the intended molecular weight, and a plurality of types of chain transfer agents may be used. Good. Examples of the chain transfer agent include primary, secondary, tertiary mercaptan, thioglycolic acid and esters thereof such as n-butyl mercaptan, isobutyl mercaptan, tert-butyl mercaptan, n-octyl mercaptan, and the like. It is done. In particular, n-butyl mercaptan is preferable because it has low volatility and can be easily removed by volatilization in the melt extrusion process. These chain transfer agents can be used in an amount of, for example, 3 parts by mass or less with respect to 100 parts by mass of the monomer component (B).

  The polymerization temperature in the bulk polymerization is not generally determined by the polymerization initiator used and the polymerization type, but is in the range of 50 to 170 ° C, more preferably in the range of 60 to 150 ° C.

  Next, the case where the transparent resin composition of the present invention is produced by polymerizing a mixture of the polymer component (A) and the monomer component (B) by a photopolymerization method will be described. Examples of the polymerization catalyst used in the production of the transparent resin composition of the present invention by a photopolymerization method include carbonyl compounds such as benzoin, benzoin isobutyl ether, benzyl, benzophenone, p-methoxybenzophenone, 1-hydroxycyclohexyl phenyl ketone, Sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide, azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile, peroxide compounds such as benzoyl peroxide and ditertiary butyl peroxide, etc. Is mentioned. Moreover, a photosensitizer can be used in combination with the photopolymerization initiator. In such a photopolymerization method, in order to produce the resin composition of the present invention having a desired refractive index, transparency and heat resistance, the polymer component (A) and the monomer component (B) are presupposed. It is most important to make the mixture mixed in a uniform state. Further, it is preferable to add a photopolymerization catalyst to this mixture and mix well, and then polymerize and cure by irradiating light such as ultraviolet rays.

  The transparent resin composition of the present invention thus obtained has little decomposition even at a high temperature of 200 ° C. or higher, and the refractive index is adjusted by the mixing ratio of the polymer component (A) and the monomer component (B). The balance of light resistance, low birefringence, low hygroscopicity, heat resistance, and mechanical properties can be appropriately adjusted. For example, by selecting the composition and mixing ratio of the polymer component (A) and the monomer component (B) so that the light transmittance measured according to the ASTM D1003 standard is 85% or more, various optical uses It can be suitably used for a transparent material. As an optical transparent material to which the transparent resin composition of the present invention can be applied, an information transmission body such as an optical fiber; an information recording medium such as a compact disk, a video disk, a write-once optical disk, a rewritable optical disk, and a magneto-optical disk; Plastic lenses of various shapes such as imaging lenses, pickup lenses, fθ lenses, spherical lenses, flat lenses; windows for buildings, automobiles, airplanes, ships, railways, etc., containers for microwave ovens, color filters, flattening of TFT elements A film etc. can be mentioned.

  As a method for molding an optical transparent material to which the transparent resin composition of the present invention is applied, known molding methods such as an extrusion molding method, an injection molding method, and a compression molding method can be used. Therefore, extrusion molding and injection molding are preferable. When the transparent resin composition of the present invention is formed into a thin film, a solution obtained by dissolving the transparent resin composition of the present invention in a solvent such as methylene chloride, dimethylformamide, acetone, It can also be applied to the surface of an object by an immersion method.

Hereinafter, the present invention will be described in more detail with reference to examples.
[Refractive index]
Using the pellet-shaped polymer, a film-like test piece having a thickness of 200 μm was formed by a melt press, and the refractive index (n _D ²⁵ ) of sodium D-line at 25 ° C. was measured using an Abbe refractometer.
[Light transmittance]
After producing an injection-molded specimen having a thickness of 2.0 mm using the pellet-shaped polymer, the light transmittance was measured based on the ASTM D1003 standard.
[Glass transition temperature (Tg)]
A differential scanning calorimeter (DSC) (manufactured by Seiko Instruments Inc., DSC-220) was used. The pelleted polymer was heated to 220 ° C. at a heating rate of 10 ° C./min, held for 5 minutes to melt, then cooled to 0 ° C. at 10 ° C./min, and again at a heating rate of 10 ° C./min. The temperature was raised at 5 ° C., held at 10 ° C./min for 5 minutes, and the glass transition temperature at this time was determined.
[Example 1]
40 parts by mass of polymethyl methacrylate (n _D = 1.492, [η] = 0.425, measured in 25 ° C. MEK, the same shall apply hereinafter), α-methylene-β-methyl-γ-butyrolactone (βMBL) (( S) The mass ratio of the isomer and the (R) isomer is 50:50) and a mixture comprising 32 parts by mass, methyl methacrylate 28 parts by mass, 1-hydroxycyclohexyl phenyl ketone 0.5 parts by mass, The mixture was sandwiched between two polyester films and irradiated with ultraviolet rays at 25 ° C. to obtain a transparent film. The refractive index of this film was 1.502, and the light transmittance was 91%. The glass transition temperature (Tg) of this film was 169 ° C.
[Comparative Example 1]
60 parts by mass of a polymer (n _D 1 = 1.508, [η] = 0.350) composed of 53% by weight of βMBL of Example 1 and 47% by weight of methyl methacrylate and polymethacrylate (n _D = 1.492). [Η] = 0.425) 40 parts by mass was dissolved in 900 parts by mass of methyl ethyl ketone. This solution was poured onto the film to make the thickness 0.1 mm, and then methyl ethyl ketone was volatilized. At that time, the film whitened.
[Example 2]
45 parts by mass of polymethyl methacrylate (n _D = 1.492, [η] = 0.425), α-methylene-β-methyl-γ-methyl-γ-butyrolactone (βMγMBL) ((S) isomer and (R) The mass ratio to the isomer is 55:45) A mixture comprising 30 parts by mass, 25 parts by mass of methyl methacrylate and 0.8 parts by mass of 1-hydroxycyclohexyl phenyl ketone is prepared. A transparent film was obtained by sandwiching between polyester films and irradiating with ultraviolet rays at 30 ° C. The refractive index of this film was 1.501 and the light transmittance was 92%. Moreover, the glass transition temperature (Tg) of this film was 162 degreeC.
[Examples 3 to 7]
Polymer (n _D = 1.489, [η] = 0.335) consisting of 98% by weight methyl methacrylate and 2% by weight methyl acrylate and α-methylene-β-ethyl-γ-butyrolactone (βEBL) ( (S) isomer and (R) isomer mass ratio is 45 to 55) a monomer mixture of 59% by mass and methyl methacrylate 41% by mass, and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator What added 1.0 mass% was used, it mixed as shown in Table 1, and it photopolymerized like Example 1, and measured the physical property of the obtained resin composition. The results are shown in Table 1.

[Examples 8 to 10 and Comparative Examples 2 and 3]
The mixing ratio of the polymer (n _D = 1.489, [η] = 0.335) composed of 98% by mass of methyl methacrylate and 2% by mass of methyl acrylate and the following monomer mixture is expressed in a mass ratio of 50. : 50, and the characteristics of the resin composition obtained by photopolymerizing a mixture obtained by adding 1.0% by mass of 1-hydroxycyclohexyl phenyl ketone to the mixture were evaluated. The results are shown in Table 2. The mixing ratio of methyl methacrylate (C) and βMBL (described in Example 1) (D) in the monomer mixture is as shown in Table 2.

[Examples 11 to 13 and Comparative Examples 4 and 5]
The mixing ratio of the polymer (n _D = 1.489, [η] = 0.335) composed of 98% by mass of methyl methacrylate and 2% by mass of methyl acrylate and the following monomer mixture is expressed in a mass ratio of 50. : 50, and the characteristics of the resin composition obtained by photopolymerizing a mixture obtained by adding 1.0% by mass of 1-hydroxycyclohexyl phenyl ketone to the mixture were evaluated. The results are shown in Table 2. The mixing ratio of methyl methacrylate and βMBL (described in Example 1) in the monomer mixture was set to a mass ratio of 50:50, and the (S) isomer and (R) isomer of βMBL (described in Example 1). The mass ratio is as shown in Table 3.

  The transparent resin composition of the present invention can easily form an optical molded article having a desired refractive index and excellent transparency and heat resistance by uniformly dispersing two kinds of polymers having different refractive indexes. Can get to. This resin composition can be suitably used for various optical transparent materials.

Claims (3)

25 to 75% by mass of a polymer component (A) mainly composed of methyl methacrylate and a general formula (1)

(In the formula, R ¹ represents a methyl group, an ethyl group or a propyl group, and R ² and R ³ independently represent a hydrogen atom, an unsubstituted or substituted alkyl group having 1 to 12 carbon atoms. Represents a phenyl group which may be unsubstituted or substituted with an alkyl group, or a cyclohexyl group which may be unsubstituted or substituted with a fluorine atom, and R ² and R ³ are bonded together. A 5- or 6-membered ring including a carbon atom may be formed, and the 5- or 6-membered ring may be substituted with a fluorine atom), and a polymer component (A A transparent resin composition obtained by polymerizing a mixture of monomer component (B) 75 to 25% by mass that produces a polymer having a higher refractive index than
A transparent resin composition characterized in that the refractive index can be adjusted by changing the mixing ratio of the polymer component (A) and the monomer component (B) within the above range.   The monomer component (B) is a lactone compound represented by the general formula (1) in a range of 10 to 78% by mass, and a monomer copolymerizable with the lactone compound in a range of 90 to 22% by mass. The transparent resin composition according to claim 1, comprising: The lactone compound represented by the general formula (1) is represented by the general formula (2).

(Wherein, R ¹ to R ³ of the general formula (showing the same as R ¹ to R ³ in 1).) And S-isomers isomer represented by the general formula (3)

(Wherein, R ¹ to R ³ of the general formula (1) shows the same as R ¹ to R ³ in.) Weight and R body isomer represented by ratio of 30: 70 to 70: 30 range The transparent resin composition according to claim 1, wherein the composition comprises a transparent resin composition.