Photoradically polymerizable composition containing vinyl sulfide compound having heterocyclic ring

Abstract

To provide a photoradically polymerizable composition which is used as a transparent resin ingredient suitable for optical applications and which not only exhibits excellent curing properties but also has a low viscosity and a high refractive index and, when cured, yields a polymer with an adjustable refractive index.SOLUTION: The photoradically polymerizable composition contains (A) a vinyl sulfide compound having a heterocyclic ring represented by the general formula (1) in the figure, (B) a radically polymerizable compound having a (meth)acrylic group, and (C) a photoradical polymerization initiator. The photoradically polymerizable composition has a refractive index (nD) of 1.50 or more. (In the general formula (1), A represents an oxygen atom or a sulfur atom, and R1 and R2 each independently represent a hydrogen atom, an alkyl group having 1-6 carbon atoms, or the like.)SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a photoradically polymerizable composition containing a vinyl sulfide compound having a heterocycle, and a polymer thereof. [Background technology]

[0002] In recent years, displays using liquid crystal or organic electroluminescence (EL) have come into widespread use, and the surfaces of these displays are covered with a laminate of multiple optical films to provide functions such as light extraction and touch panel functions. In addition, the substrates used are also shifting from glass substrates to flexible substrates using resins, and various film laminates are also used for sealing. In these displays, controlling the light from the outside and the light emitted from the inside is extremely important in terms of display quality.

[0003] On the other hand, these laminates of films each have a different refractive index for light, and the difference in the refractive index causes various characteristics to be expressed or, conversely, various problems to occur. For example, in a color filter, if the pigment type is different, the refractive index of the pixels will be different, and the scattering of light will increase at the interface with the overcoat layer, resulting in a problem of loss of transmitted light. In addition, the laminate of films is generally bonded with an adhesive composition, but it is known that if a general acrylic adhesive is used to bond a high refractive index material, reflection will occur at the interface due to the difference in the refractive index between the two. For this reason, there are known examples in which a refractive index adjuster is used to adjust the refractive index of the adhesive. For example, in Patent Document 1, a compound having a triazine ring is added to an acrylic polymer to develop an adhesive with a high refractive index of 1.55 or more.

[0004] In addition, when gas barrier films are used to protect the surface of displays, there are two interfaces between the plastic substrate, the evaporated thin film layer, and the gas barrier coating layer, which causes color unevenness due to interference light, which is a problem in appearance. In general, when two films are laminated, the greater the difference in refractive index between them, the greater the reflection at the contact surface of the films, which is thought to cause problems with light extraction. Therefore, methods to reduce the difference in refractive index between laminated films are being considered. For example, in touch panels, etc., films patterned with a metal oxide called ITO (Indium Tin Oxide), which transmits visible light, are used, but since this ITO is an inorganic material, it has a higher light reflectance than organic materials, and the reflectance of the ITO surface and the substrate film (PET) differs, which causes the problem that the ITO pattern becomes visible. As such, resin films generally have a low refractive index, and attempts to increase the refractive index of the film are being considered. For example, Patent Document 2 discloses a polymerizable composition containing a (meth)acrylate compound having a triazine skeleton and a refractive index modifier, and by using a (meth)acrylate compound having a fluorene skeleton as the refractive index modifier, a cured product having a refractive index of 1.557 or more and 1.571 or less at 589 nm after curing is obtained. Thus, there is a demand for a refractive index modifier that can increase the refractive index of existing polymerizable compositions.

[0005] In general, the refractive index of a film and the refractive index of the polymerizable composition that is its raw material are positively correlated, and in order to obtain a polymer with a high refractive index, the polymerizable compound that constitutes the polymerizable composition must have a high refractive index. Therefore, it is considered that the refractive index can be adjusted to be high by adding a polymerizable compound with a high refractive index that is copolymerizable with an existing polymerizable compound.

[0006] As a method for increasing the refractive index of a polymerizable compound, it is already widely known to introduce an aromatic ring into the molecular structure, or to introduce a halogen atom (excluding fluorine) or a sulfur atom. For example, as a polymerizable compound having an aromatic ring in the molecular structure, those having a polycyclic aromatic ring such as biphenyl, naphthalene, fluorene, anthracene, etc., in addition to a benzene ring, are known. However, a polymerizable compound having a single benzene ring in the molecular structure does not have a sufficient refractive index. In addition, although a polymerizable compound having a polycyclic aromatic ring such as biphenyl, naphthalene, fluorene, anthracene in the molecular structure is expected to have a high refractive index, in most cases it becomes a high viscosity liquid or crystalline solid, so there is a problem that the handling properties such as solubility are reduced. For example, Patent Document 3 discloses a composition containing a (meth)acrylate having a fluorene skeleton as a curable composition that can obtain a cured product having a high refractive index and a low Abbe number. Among them, 9,9-bis(4-(2-acryloyloxyethoxy)phenyl)fluorene has a refractive index nD of 1.608 and a viscosity at 25°C of 100,000 mPa·s or more.

[0007] Furthermore, a monomer composition having a sulfur atom with a high intrinsic refractive index has also been reported. For example, in Patent Document 4, an aromatic ring is introduced via a sulfur atom to increase the refractive index. In Patent Document 5, a polymerizable composition mainly composed of a thio(meth)acrylate monomer is disclosed, and bis[(4-methacryloylthio)phenyl] sulfide and the like are disclosed. In addition, in Patent Document 6, a compound having a methylthiophenyl group is disclosed as a novel (meth)acrylic acid ester for dilution, which has a low viscosity, a high refractive index, and a high heat resistance of its homopolymer. In Patent Document 7, a polymerizable composition is disclosed that uses a sulfide compound and a (meth)acrylate compound containing a sulfur compound as a liquid curable ink composition capable of forming a cured product with a high refractive index and applicable to the inkjet method, and uses zirconium oxide nanocrystals as metal compound nanocrystals.

[0008] Furthermore, Patent Document 8 discloses a (meth)acrylic acid ester having a condensed ring selected from the group consisting of a naphthalene ring, an anthracene ring, a benzothiazole ring, a benzoxazole ring, a benzimidazole ring, a fluorene ring, and a phenanthrene ring, as a polymerizable compound having a high refractive index, high solubility in a polymerizable compound having an aromatic ring, and high visible light transmittance of the cured product. Patent Document 9 discloses a (meth)acrylic acid ester having an aryl group or a heteroaryl group as a method for producing a high refractive index symmetrical (meth)acrylic acid ester, and a compound having a mercaptobenzothiazole group as the heteroaryl group. Similarly, Patent Document 10 discloses a (meth)acrylic acid ester compound having a benzothiazole ring as a sulfur atom-containing (meth)acrylic acid ester. However, all of these acrylic esters having a high refractive index have the problem of high viscosity.

[0009] Furthermore, Patent Document 11 discloses a compound in which an aromatic ring or an aromatic heterocycle is introduced into three of the four molecular chains of a quaternary carbon of a pentaerythritol skeleton, and a (meth)acrylic group is introduced into the remaining one. As the aromatic heterocycle, a benzoxazole ring, a thienoxazole ring, a thiazolooxazole ring, an oxazolooxazole ring, an oxazoloimidazole ring, an oxazolopyridine ring, an oxazolopyridazine ring, an oxazolopyrimidine ring, an oxazolopyrazine ring, a naphthoxazole ring, a quinolinoxazole ring, a dioxazolopyrazine ring, a phenoxazine ring, a benzothiazole ring, a furothiazole ring, a thienothiazole ring, a thiazolothiazole ring, a thiazoloimidazole ring, a thienothiadiazole ring, a thiazolothiadiazole ring, a thiazolopyridine ring, a thiazolopyridazine ring, a thiazolopyrimidine ring, a thiazolopyrazine ring, a naphthothiazole ring, a quinolinothiazole ring, and a phenothiazine ring are disclosed. Among them, a thiazolothiadiazole ring is disclosed.

[0010] However, most of these high refractive index polymerizable compounds have an acrylic acid ester structure. By using acrylic acid ester, transparency and high polymerizability can be expected. However, on the other hand, there is a drawback that the viscosity becomes high. For example, Patent Document 12 discloses a high refractive index monomer that can be cured with ultraviolet light and is useful for manufacturing optical articles, especially light control films, and among them, as a heterocyclic (meth)acrylate, a meth)acrylate having a benzothiazole group is disclosed. It is described that the refractive index of 1,3-bis(2-mercaptobenzothiazoyl)propan-2-yl acrylate is 1.629 and the viscosity is 860 cP, and the refractive index of 2-(4-chlorophenoxy)-1-[(phenylthio)methyl]ethyl acrylate is 1.5792 and the viscosity is 352 cP.

[0011] On the other hand, in recent years, when these high refractive index polymerizable compounds are used in optical applications such as displays, it is expected that they will be used in coating methods such as inkjet printing, and low viscosity is also an important factor required for polymerizable compositions containing these high refractive index polymerizable compounds as inkjet inks. For example, low viscosity polymerizable compositions of 30 mPa s or less are required for inkjet inks, and polymerizable compounds that have a high refractive index, high polymerizability, and low viscosity are expected.

[0012] Polymerizable compounds having a vinyl sulfide group are also known. Patent Document 13 discloses a compound having a polymerizable functional group and a diaryl sulfide skeleton as a composition for nanoimprinting, and discloses a vinyl group, an allyl group, a methacryloyl group, and an acryloyl group as the polymerizable functional group. Patent Documents 14 to 16 disclose polymerizable compositions containing phenyl vinyl sulfide.

[0013] Patent Documents 17 and 18 describe the use of an organic peracid and / or an azo compound to radically polymerize a plastic lens material such as 2-vinylthiobenzothiazole and a radical polymerizable compound such as divinylbenzene under heating. Patent Document 19 describes the use of an organic peracid and / or an azo compound to radically polymerize a polymerizable compound having an aromatic heterocycle including 2-vinylthiobenzothiazole under heating as an organic electroluminescence material. Both of these methods use a thermal radical polymerization initiator, and have different compositions from those of the present invention. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] JP 2023-38116 A [Patent Document 2] JP 2012-72316 A [Patent Document 3] JP 2019-14767 A [Patent Document 4] JP 2020-37693 A [Patent Document 5] Japanese Patent Application Publication No. 9-25321 [Patent Document 6] JP 2017-190326 A [Patent Document 7] JP 2021-31669 A [Patent Document 8] JP 2018-104696 A [Patent Document 9] JP 2012-82145 A [Patent Document 10] JP 2023-32499 A [Patent Document 11] JP 2017-14213 A [Patent Document 12] JP 2005-133071 A [Patent Document 13] JP 2022-170092 A [Patent Document 14] JP 2022-128911 A [Patent Document 15] International Publication No. 2018 / 062196 Brochure [Patent Document 16] Patent Publication No. 2021-55051 [Patent Document 17] Japanese Patent Application Publication No. 2-265907 [Patent Document 18] Japanese Patent Application Publication No. 4-225007 [Patent Document 19] JP 2000-87027 A Summary of the Invention [Problem to be solved by the invention]

[0015] To provide a photoradical polymerizable composition which is used as a transparent resin raw material suitable for optical applications, has excellent curing properties, low viscosity and a high refractive index, and allows adjustment of the refractive index of a copolymer obtained by curing. [Means for solving the problem]

[0016] As a result of intensive research, the present inventors have found that a photoradical polymerizable composition containing a vinyl sulfide compound having a specific structure as a resin raw material has low viscosity and a very high refractive index, and can form a copolymer composition with various radically polymerizable compounds, and that this copolymer composition can be easily polymerized under practical conditions to give a polymer with a high refractive index, thereby completing the present invention.

[0017] The first invention is a photoradical polymerizable composition containing (A) a vinyl sulfide compound having a heterocycle represented by general formula (1), (B) a radical polymerizable compound having a (meth)acrylic group, and (C) a photoradical polymerization initiator, wherein the refractive index (n D ) is 1.50 or more.

[0018] [ka]

[0019] In the general formula (1), A represents an oxygen atom or a sulfur atom, R 1 , R 2 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or an arylthio group having 6 to 10 carbon atoms; R 1 and R 2 may be bonded to each other to form a saturated or unsaturated ring.

[0020] A second invention resides in the photoradically polymerizable composition according to the first invention, characterized in that the viscosity of the photoradically polymerizable composition at 25° C. is 30 mPa·s or less.

[0021] A third invention resides in the photoradically polymerizable composition according to the first invention, characterized in that the (B) radically polymerizable compound having a (meth)acryl group is at least one radically polymerizable compound selected from the group consisting of monofunctional (meth)acrylates, monofunctional (meth)acrylamides, polyfunctional (meth)acrylates, and polyfunctional (meth)acrylamides.

[0022] A fourth invention resides in the photoradical polymerizable composition according to the first invention, characterized in that the (C) photoradical polymerization initiator is one or more photoradical polymerization initiators selected from the group consisting of alkylphenone-based photoradical polymerization initiators, benzophenone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, oxime ester-based photoradical polymerization initiators, α-aminoacetophenone-based photoradical polymerization initiators, biimidazole-based photoradical polymerization initiators, and thioxanthone-based photoradical polymerization initiators.

[0023] A fifth invention resides in a photoradically polymerizable composition according to the first invention, characterized in that the content of the vinyl sulfide compound having a heterocycle (A) represented by general formula (1) is 10% by weight or more, relative to 100% by weight of the total amount of the photoradically polymerizable composition.

[0024] A sixth aspect of the present invention resides in a polymerization method comprising irradiating the photoradically polymerizable composition according to any one of the first to fifth aspects with active energy rays.

[0025] A seventh invention resides in the polymerization method according to the sixth invention, characterized in that the active energy rays to be irradiated have a peak wavelength in the wavelength range of 350 nm to 420 nm.

[0026] The eighth invention is a polymer obtained by polymerizing the photoradical polymerizable composition according to any one of the first to fifth inventions, and the refractive index (n D ) is 1.50 or more.

[0027] In the present invention, (meth)acrylate means acrylate or methacrylate, (meth)acryloyl means acryloyl or methacryloyl, and (meth)acrylic means acrylic or methacrylic. In addition, the refractive index in the present invention is the refractive index (n D Furthermore, the viscosity in the present invention means a value measured at 25° C. using an E-type viscometer, unless otherwise specified. Effect of the Invention

[0028] The photoradical polymerizable composition of the present invention, which contains a vinyl sulfide compound having a heterocycle, a radical polymerizable compound having a (meth)acrylic group, and a photoradical polymerization initiator, has a low viscosity and a high refractive index and is easily polymerized under practical conditions, and a polymer having a very high refractive index can be obtained by polymerizing the photoradical polymerizable composition of the present invention. [Brief description of the drawings]

[0029] [Figure 1] A graph showing the relationship between the ratio of 2-vinylthiobenzoxazole added to a copolymer composition of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate and the refractive index and viscosity of the composition. The smooth line smoothly connects each of the plotted points. [Diagram 2] A graph showing the relationship between the ratio of 2-vinylthiobenzothiazole added to a copolymer composition of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate and the refractive index and viscosity of the composition. The smooth line smoothly connects each of the plotted points. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The present invention will be described in detail below.

[0031] ((A) Vinyl sulfide compound having a heterocycle represented by general formula (1)) The vinyl sulfide compound having a heterocycle of the present invention is represented by general formula (1).

[0032] [ka]

[0033] In the general formula (1), A represents an oxygen atom or a sulfur atom, R 1 , R 2 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or an arylthio group having 6 to 10 carbon atoms; R 1 and R 2 may be bonded to each other to form a saturated or unsaturated ring.

[0034] In the general formula (1), R 1 , R 2The alkyl group having 1 to 6 carbon atoms represented by the formula (I) may be a straight-chain alkyl group or a branched alkyl group. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, a 2-methylbutyl group, a neopentyl group, a 1-ethylpropyl group, an n-hexyl group, a 4-methylpentyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 1-methylpentyl group, a 3,3-dimethylbutyl group, a 2,2-dimethylbutyl group, a 1,1-dimethylbutyl group, and a 1,2-dimethylbutyl group.

[0035] Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group, a tolyl group, a naphthyl group, and the like, which may have a substituent. Examples of the alkoxy group having 1 to 6 carbon atoms include a linear, branched or cyclic alkoxy group, such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a hexyloxy group, and a cyclohexyloxy group. Examples of the aryloxy group having 6 to 10 carbon atoms include a phenyloxy group, a tolyloxy group, and a naphthyloxy group, which may have a substituent. Examples of the alkylthio group having 1 to 6 carbon atoms include a methylthio group, an ethylthio group, an n-propylthio group, an i-propylthio group, an n-butylthio group, an i-butylthio group, an n-amylthio group, an i-amylthio group, an n-hexylthio group, and a cyclohexylthio group. Examples of the arylthio group having 6 to 10 carbon atoms include a phenylthio group, a naphthylthio group, and the like.

[0036] In the general formula (1), when A is an oxygen atom, the vinyl sulfide compound has a benzoxazole group, and when A is a sulfur atom, the vinyl sulfide compound has a benzothiazole group.

[0037] Specific examples of the vinyl sulfide compound having a benzoxazole group in which A in the general formula (1) is an oxygen atom include 2-vinylthiobenzoxazole, 2-vinylthio-5-methylbenzoxazole, 2-vinylthio-6-methylbenzoxazole, 2-vinylthio-4-methylbenzoxazole, 2-vinylthio-5,6-dimethylbenzoxazole, 2-vinylthio-naphtho[2,1-d]benzoxazole, and 2-vinylthio-naphtho[2,1-d]benzoxazole. [1,2-d]benzoxazole, 2-vinylthio-5-phenylbenzoxazole, 2-vinylthio-5-tert-butylbenzoxazole, 2-vinylthio-4-methoxybenzoxazole, 2-vinylthio-5-methoxybenzoxazole, 2-vinylthio-6-methoxybenzoxazole, 2-vinylthio-6-ethoxybenzoxazole, 2-vinylthio-4-methylthiobenzoxazole, 2-vinylthio-5-methylthiobenzoxazole, 2-vinylthio-6-methylthiobenzoxazole, 2-vinylthio-6-ethylthiobenzoxazole, 2-vinylthio-6-phenylthiobenzoxazole, and the like.

[0038] Specific examples of vinyl sulfide compounds having a benzothiazole group in which A in the general formula (1) is a sulfur atom include 2-vinylthiobenzothiazole, 2-vinylthio-5-methylbenzothiazole, 2-vinylthio-6-methylbenzothiazole, 2-vinylthio-4-methylbenzothiazole, 2-vinylthio-5,6-dimethylbenzothiazole, 2-vinylthio-naphtho[2,1-d]benzothiazole, 2-vinylthio-naphtho[1,2-d]benzothiazole, 2-vinylthio-5-phenylbenzothiazole, 2-vinyl Examples of such benzothiazole include thio-5-tert-butylbenzothiazole, 2-vinylthio-4-methoxybenzothiazole, 2-vinylthio-5-methoxybenzothiazole, 2-vinylthio-6-methoxybenzothiazole, 2-vinylthio-6-ethoxybenzothiazole, 2-vinylthio-4-methylthiobenzothiazole, 2-vinylthio-5-methylthiobenzothiazole, 2-vinylthio-6-methylthiobenzothiazole, 2-vinylthio-6-ethylthiobenzothiazole, and 2-vinylthio-6-phenylthiobenzothiazole.

[0039] Among the compounds exemplified above, 2-vinylthiobenzoxazole of the following structural formula (2) and 2-vinylthiobenzothiazole of the structural formula (3) are preferred in terms of ease of synthesis, refractive index and viscosity. In addition, a compound in which A in general formula (1) is an oxygen atom is preferred in terms of polymerization at low exposure doses, high transmittance and low yellowness of the resulting polymer, and 2-vinylthiobenzoxazole of the structural formula (2) is particularly preferred in terms of ease of synthesis.

[0040] [ka]

[0041] [ka]

[0042] (Synthesis method) The compound of general formula (1) can be synthesized by a known method. For example, as shown in the following reaction formula 1, a 2-mercaptobenzoxazole compound or a 2-mercaptobenzothiazole compound is reacted with a dihalogenated ethane such as 1,2-dibromoethane in the presence of a base, and then dehydrohalogenated in the presence of a base, thereby synthesizing the compound of general formula (1).

[0043] [ka]

[0044] In reaction formula 1, A represents an oxygen atom or a sulfur atom, and R 1 , R 2 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or an arylthio group having 6 to 10 carbon atoms; R 1 and R 2 may be bonded to each other to form a saturated or unsaturated ring. X represents a chlorine atom or a bromine atom, and the two X's may be the same or different.

[0045] Usually, the reaction of the compound of general formula (4) with dihalogenated ethane induces a substitution reaction of the thiol group to produce a thioether compound, and then almost simultaneously, the hydrogen halide is eliminated to produce a double bond, and the desired vinyl sulfide compound having a heterocycle of general formula (1) can be obtained without isolating the intermediate.

[0046] The vinyl sulfide having a heterocycle represented by the general formula (1) synthesized by the above method is a compound having an extremely low viscosity and a high refractive index. For example, 2-vinylthiobenzoxazole, which is the vinyl sulfide having a heterocycle of the present invention, is a liquid compound, has an extremely low viscosity of 4.2 mPa·s at 25°C, and exhibits a high refractive index of 1.62. 2-vinylthiobenzothiazole is also a liquid compound, has an extremely low viscosity of 7.6 mPa·s at 25°C, and exhibits a very high refractive index of 1.68.

[0047] In addition, the vinyl sulfide having a heterocycle represented by the general formula (1) of the present invention can be polymerized and cured using a commercially available photoradical polymerization initiator, and is a very useful polymerizable compound that can be polymerized and cured not only with a light source such as a high-pressure mercury lamp, but also with a light source having a single wavelength and weak irradiation energy such as an ultraviolet LED or a semiconductor laser. It is also highly compatible with other polymerizable compounds such as (meth)acrylic acid esters, and the photoradical polymerizable composition obtained by mixing it can also maintain a low viscosity, and the obtained polymerized and cured product exhibits a high refractive index. In terms of a high refractive index, 2-vinylthiobenzothiazole is preferred. In addition, 2-vinylthiobenzoxazole is particularly preferred because it is polymerized at a low exposure dose, and the polymer exhibits an ultra-high refractive index, high transmittance, and low YI (yellowing index).

[0048] ((B) Radical Polymerizable Compound Having a (Meth)acrylic Group) The vinyl sulfide compound having a heterocycle represented by the general formula (1) of the present invention is compatible with various radical polymerizable compounds and can form a copolymerizable composition. For example, vinyl ether, vinyl sulfide (excluding vinyl sulfide having a heterocycle represented by the general formula (1)), (meth)acrylic acid, (meth)acrylonitrile, monofunctional (meth)acrylate, monofunctional (meth)acrylamide, polyfunctional (meth)acrylate, polyfunctional (meth)acrylamide, etc., or oligomers thereof can be mentioned. Among these radical polymerizable compounds, radical polymerizable compounds having a Q value of 0.9 or less are preferred, and in particular, radical polymerizable compounds having a (meth)acrylic group are preferred in terms of practicality such as transparency. And, it is preferred to use these radical polymerizable compounds in combination with the radical polymerizable compound and in a mixing ratio such that the viscosity at 25°C of the photoradical polymerizable composition, which is a mixture of the vinyl sulfide compound having a heterocycle of the present invention, is 30 mPa·s or less.

[0049] As the radically polymerizable compound having a (meth)acrylic group, monofunctional (meth)acrylates, monofunctional (meth)acrylamides, polyfunctional (meth)acrylates and polyfunctional (meth)acrylamides are preferred. Examples of monofunctional (meth)acrylates that can be used include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, hydroxyethyl acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, tridecyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, phenoxyethyl (meth)acrylate, methyl acrylate, ethyl ... ethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxytetraethylene glycol (meth)acrylate, phenoxyhexaethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, tetrahydrofurfuryl acrylate, 2-methyl-2-adamantyl (meth)acrylate, allyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, and the like.

[0050] Further examples include hydroxyl group-containing (meth)acrylic monomers, carboxyl group-containing (meth)acrylic monomers, amino group-containing (meth)acrylic monomers, acetoacetyl group-containing (meth)acrylic monomers, isocyanate group-containing (meth)acrylic monomers, glycidyl group-containing (meth)acrylic monomers, and (meth)acrylic monomers having an aromatic hydrocarbon group.

[0051] Examples of hydroxyl group-containing (meth)acrylic monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; hydroxyalkyl (meth)acrylamides such as N-hydroxyethyl (meth)acrylamide and N-hydroxypropyl (meth)acrylamide; and 2-acryloyloxyethyl 2-hydroxyethyl phthalate. Examples of the monomers include primary hydroxyl group-containing (meth)acrylic monomers such as N-methylol (meth)acrylamide, secondary hydroxyl group-containing (meth)acrylic monomers such as 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy 3-phenoxypropyl (meth)acrylate, 3-chloro 2-hydroxypropyl (meth)acrylate, and 2-hydroxy 3-phenoxypropyl (meth)acrylate, and tertiary hydroxyl group-containing (meth)acrylic monomers such as 2,2-dimethyl 2-hydroxyethyl (meth)acrylate. Among these, hydroxyalkyl (C1-C6, linear or branched) (meth)acrylates are preferably used.

[0052] Examples of the carboxyl group-containing (meth)acrylic monomer include monocarboxylic acids such as (meth)acrylic acid and crotonic acid, and dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, citraconic acid, and itaconic acid, and among these, (meth)acrylic acid is preferably used.

[0053] Examples of the amino group-containing (meth)acrylic monomer include aminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-di-t-butylaminoethyl (meth)acrylate, and N,N-diethylaminoethyl (meth)acrylate; and aminoalkyl (C1 to C6, linear or branched) (meth)acrylamides such as N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, and N,N-dimethylaminopropyl (meth)acrylamide.

[0054] Examples of the acetoacetyl group-containing (meth)acrylic monomer include 2-(acetoacetoxy)ethyl (meth)acrylate.

[0055] Examples of the isocyanate group-containing (meth)acrylic monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

[0056] Examples of the glycidyl group-containing (meth)acrylic monomer include glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, N-2-hydroxyethyl (meth)acrylamide glycidyl ether, and N-methyl-N-2-hydroxyethyl (meth)acrylamide glycidyl ether.

[0057] Examples of the (meth)acrylic monomer having an aromatic hydrocarbon group include (meth)acrylic monomers having a benzene ring group, such as benzyl (meth)acrylate, phenyl (meth)acrylate, benzyl phenyl (meth)acrylate, p-phenyl benzyl acrylate, pt-butyl phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxy diethylene glycol (meth)acrylate, ethylene oxide modified nonylphenol (meth)acrylate, ethylene oxide modified cresol (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, methoxybenzyl (meth)acrylate, m-phenoxybenzyl (meth)acrylate, and chlorobenzyl (meth)acrylate. Examples of the monomers include (meth)acrylic monomers having a naphthalene ring group, such as 4-methoxy-1-naphthoxy)ethyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, and 2-naphthylmethyl acrylate; and also (meth)acrylic monomers having a biphenyl ring group, such as p-biphenyl (meth)acrylate, ethoxylated-p-biphenyl (meth)acrylate, o-phenylphenol (meth)acrylate, and ethoxylated-o-phenylphenol (meth)acrylate; and also fluorenyl (meth)acrylate, 9-fluorenylmethyl (meth)acrylate (9-(meth)acryloyloxymethylfluorene), and the like. In addition to the compounds exemplified here, examples of the aromatic hydrocarbon group include (meth)acrylic monomers having an azulene ring group, an anthracene ring group, a phenanthrene ring group, a pyrene ring group, a chrysene ring group, a naphthacene ring group, a triphenylene ring group, an o-terphenyl ring group, an m-terphenyl ring group, a p-terphenyl ring group, a fluorene ring group, or the like.Many of these (meth)acrylic monomers having an aromatic hydrocarbon group have a high refractive index but also have a high viscosity. By forming a copolymer composition with a vinyl sulfide having a heterocycle represented by the general formula (1) of the present invention, a photoradical polymerizable composition having a high refractive index but low viscosity can be obtained.

[0058] Examples of monofunctional (meth)acrylamides include N-alkyl (C1 to C18, linear or branched) (meth)acrylamides, N-alkoxy (C1 to C6, linear or branched) alkyl (C1 to C18, linear or branched) (meth)acrylamides, N-hydroxyalkyl (C1 to C18, linear or branched) (meth)acrylamides, N,N-dihydroxyalkyl (C1 to C18, linear or branched) (meth)acrylamides, N- ... Examples of the monomer include C18, linear or branched)-N-alkyl (C1 to C18, linear or branched) (meth)acrylamide, N-vinylpyrrolidone, N-vinylcaprolactam, N-(dialkyl (C1 to C6, linear or branched) amino) alkyl (C1 to C18, linear or branched) (meth)acrylamide, N,N-dialkyl (C1 to C18, linear or branched) (meth)acrylamide, N-acryloylmorpholine, and diacetone (meth)acrylamide. In particular, from the viewpoint of easy availability as a high-purity industrial product, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, N-acryloylmorpholine, diacetone acrylamide, N-(dimethylamino)propyl (meth)acrylamide, and N-hydroxyethylacrylamide are more preferable. These monofunctional monomers may be used alone or in combination of two or more.

[0059] Examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, ditetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, ) acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate ) acrylate, ethylene oxide modified phosphoric acid di(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol tetra(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethylene oxide modified bisphenol A di(meth)acrylate, propylene oxide modified bisphenol A di(meth)acrylate, cyclohexane dimethanol di(meth)acrylate, acrylate ester (dioxane glycol diacrylate), alkoxylated hexanediol di(meth)acrylate, alkoxylated cyclohexane dimethanol di(meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate and other monomers and oligomers.From the viewpoint of commercial availability, examples of polyfunctional (meth)acrylates include, for example, trade names CN2203 and CN2270 manufactured by SARTOMER, and trade names M-6100 and M-8060 manufactured by Toa Gosei Co., Ltd.; examples of urethane acrylates include, for example, trade names UV-3200B, UV-3000B, UV-6640B, UV-3700B, UV-3310B, and UV-7000B manufactured by Nippon Synthetic Chemical Industry Co., Ltd.; trade names U-4HA and U-200PA manufactured by Shin-Nakamura Chemical Co., Ltd.; and trade names EBECRYL245, EBECRYL1259, and EBECRYL245 manufactured by Daicel-Cytec Co., Ltd. ECRYL8210, EBECRYL284, EBECRYL8402, SARTOMER's trade names CN944, CN969, CN9002, CN9029, Negami Chemical Industries' trade names UN1255, UN-5507, Kyoeisha Chemical's trade names AH-600, UA-306I, etc. can be used, and epoxy (meth)acrylates can be Daicel-Cytec's trade names EBECRYL1259, EBECRYL605, EBECRYL1606, SARTOMER's trade names CN110, CN120, CN153, etc. Furthermore, from the viewpoint of the viscosity of the resin composition and ease of handling, etc., urethane acrylate UV-6640B or U-200PA is more preferable. These polyfunctional (meth)acrylates may be used alone or in combination of two or more.

[0060] Examples of polyfunctional (meth)acrylamides include methylene bis(meth)acrylamide, ethylene bis(meth)acrylamide, diallyl (meth)acrylamide, and urethane di(meth)acrylamide.

[0061] In the photoradically polymerizable composition of the present invention, the radically polymerizable compound having a (meth)acrylic group is preferably a (meth)acrylic monomer having an aromatic hydrocarbon group in terms of a high refractive index, but the effect of the vinyl sulfide compound having a heterocycle represented by general formula (1) as a refractive index adjuster becomes important in copolymerization with an aliphatic (meth)acrylic monomer having a low refractive index.

[0062] The content of the vinyl sulfide compound having a heterocycle (A) represented by general formula (1) is preferably 1% by weight or more, based on 100% by weight of the total amount of the photoradical polymerizable composition. From the viewpoints of lowering the viscosity and increasing the refractive index, the content is more preferably 10% by weight or more, and even more preferably 20% by weight or more.

[0063] In the photoradical polymerizable composition of the present invention, compositions having various refractive indices and viscosities can be prepared by adjusting the composition ratio of (A) the vinyl sulfide compound having a heterocycle represented by general formula (1) and (B) the radical polymerizable compound having a (meth)acrylic group. A preferred composition ratio is selected to obtain a desired refractive index and viscosity. For example, in an example in which 2-vinylthiobenzoxazole is used as (A) the vinyl sulfide compound having a heterocycle represented by general formula (1) and trimethylolpropane triacrylate is used as (B) the radical polymerizable compound having a (meth)acrylic group, it can be seen from FIG. 1 that a copolymerizable composition having a viscosity of 30 mPa·s or less at 25°C can be prepared by setting the amount of 2-vinylthiobenzoxazole to 32% by weight or more.

[0064] ((C) Photoradical polymerization initiator) A photoradical polymerization initiator is added to the photoradical polymerizable composition of the present invention. The photoradical polymerization initiator refers to a compound that generates radicals when irradiated with light, i.e., absorbs light energy, decomposes and / or reacts to generate radicals, and does not include a compound that generates radicals by heat, i.e., a compound that absorbs thermal energy and decomposes to generate radical species, such as a peroxide-based radical polymerization initiator or an azo-based radical polymerization initiator. As the photoradical polymerization initiator, any commonly used one can be used without any particular restrictions, and for example, any one or more photoradical polymerization initiators selected from the group consisting of alkylphenone-based photoradical polymerization initiators, benzophenone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, oxime ester-based photoradical polymerization initiators, α-aminoacetophenone-based photoradical polymerization initiators, biimidazole-based photoradical polymerization initiators, triazine-based photoradical polymerization initiators, and thioxanthone-based photoradical polymerization initiators can be used.

[0065] Examples of alkylphenone-based photoradical polymerization initiators include 2,2'-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane. -1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzylmethyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-morpholinophenyl)-1-butanone, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, and N,N-dimethylaminoacetophenone.

[0066] Examples of the benzophenone-based photoradical polymerization initiator include benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone.

[0067] Examples of the acylphosphine oxide-based photoradical polymerization initiator include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (product name "OmniradTPO" manufactured by IGM Group B.V.) and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omnirad819" manufactured by IGM Group B.V.).

[0068] Examples of oxime ester photoradical polymerization initiators include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(o-benzoyloxime) (trade name "IrgacureOXE01" manufactured by BASF, Irgacure is a registered trademark of BASF), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime) (trade name "IrgacureOXE02" manufactured by BASF), [8-[[(acetyloxy)imino][2-(2,2,3,3-tetrafluoropropoxy)phenyl]methyl]-11-(2-ethylhexyl)-11H-benzo[a]carbazol-5-yl]-, (2,4,6-trimethylphenyl) (trade name "IrgacureOXE03" manufactured by BASF), and the like.

[0069] Examples of the α-aminoacetophenone-based photoradical polymerization initiator include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (trade name "Omnirad907" manufactured by IGM Group B.V.), 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (trade name "Omnirad369" manufactured by IGM Group B.V.), and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholino-4-yl-phenyl)butan-1-one (trade name "Omnirad379" manufactured by IGM Group B.V.).

[0070] Examples of the biimidazole-based photoradical polymerization initiator include 2,4,5-triarylimidazole dimers such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, and 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer.

[0071] Examples of the triazine-based photoradical polymerization initiator include 2-(3,4-methylenedioxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, and 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine.

[0072] Examples of the thioxanthone-based photoradical polymerization initiator include 2,4-diethylthioxanthone and 2-isopropylthioxanthone.

[0073] The alkylphenone-based photoradical polymerization initiator, the benzophenone-based photoradical polymerization initiator, the acylphosphine oxide-based photoradical polymerization initiator, the oxime ester-based photoradical polymerization initiator, the α-aminoacetophenone-based photoradical polymerization initiator, the biimidazole-based photoradical polymerization initiator, the triazine-based photoradical polymerization initiator, and the thioxanthone-based photoradical polymerization initiator that can be used in the present invention can each be used alone, or two or more types can be used in combination depending on the application, etc.

[0074] Among the above-mentioned photoradical polymerization initiators, biimidazole-based photoradical polymerization initiators, alkylphenone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, and oxime-based photoradical polymerization initiators are preferred. In terms of activity, acylphosphine oxide-based photoradical polymerization initiators and oxime ester-based photoradical polymerization initiators are particularly preferred.

[0075] The amount of the photoradical polymerization initiator added is preferably 0.1% by weight or more and 10% by weight or less based on the photoradical polymerizable composition.

[0076] (Photoradical polymerization sensitizer) Conventionally, high pressure mercury lamps have been used as light sources in photoradical polymerization, but due to problems such as high energy consumption, curing devices using LED light sources, which have low running costs and little impact on the natural environment, have come to be used. However, these LED light sources emit light with long wavelengths such as 365nm, 385nm, 395nm, and 405nm, and unlike high pressure mercury lamps, they emit light of a single wavelength, so there is a problem that the irradiation energy is weak. With such LED lamps, it is often the case that conventional photoradical polymerization initiators cannot cure sufficiently. In order to deal with such long wavelength, single light LED lamps, it is preferable to further add a photoradical polymerization sensitizer. By adding a photoradical polymerization sensitizer that absorbs long wavelength light, the radical generation reaction of the photoradical polymerization initiator can be promoted, and the reactivity of the radical polymerization can be improved.

[0077] The photoradical polymerization sensitizer can be any commonly used sensitizer that is active to light of the irradiation wavelength and can be used without any particular limitation. For example, thioxanthone-based sensitizers such as isopropylthioxanthone and diethylthioxanthone, benzophenone-based sensitizers such as 4,4'-bis(diethylamino)benzophenone, anthracene-based sensitizers such as 9,10-diethoxyanthracene, 9,10-dibutoxyanthracene, 9,10-bisheptanoyloxyanthracene and 9,10-bisoctanoyloxyanthracene, coumarin-based sensitizers such as coumarin and ketocoumarin, acridine orange, camphorquinone, etc. can be used.

[0078] The amount of the photoradical polymerization sensitizer added is preferably 0.1% by weight or more and 10% by weight or less based on the photoradical polymerizable composition.

[0079] The photoradical polymerizable composition of the present invention may contain a polymerization accelerator depending on the photoradical polymerization initiator used. Examples of the polymerization accelerator include amine compounds such as ethyl p-dimethylaminobenzoate, 2-ethylhexyl p-dimethylaminobenzoate, methyl p-dimethylaminobenzoate, 2-dimethylaminoethyl benzoate, and butoxyethyl p-dimethylaminobenzoate.

[0080] The photoradical polymerizable composition of the present invention may contain a polymerization inhibitor to enhance the stability of the composition. Examples of the polymerization inhibitor include at least one compound selected from the group consisting of hydroquinone, hydroquinone monomethyl ether, 1,4-benzoquinone, tert-butylhydroquinone, and 4-tert-butylpyrocatechol.

[0081] Furthermore, the photoradical polymerizable composition of the present invention may contain a surfactant, and the surfactant is preferably a nonionic surfactant. By containing a nonionic surfactant, the coating property when the radical polymerizable composition is applied to a substrate to obtain a resin film is improved, and a coating film of uniform thickness can be obtained. The nonionic surfactant is, for example, a compound containing a fluorine group (for example, a fluorinated alkyl group) or a silanol group, or a compound having a siloxane bond as the main skeleton. It is preferable to use one containing a fluorine-based surfactant or a silicone-based surfactant. Examples of fluorine-based surfactants include, but are not limited to, Megafac F-171, F-173, F-444, F-470, F-471, F-475, F-482, F-477, F-554, F-556, and F-557 manufactured by DIC Corporation, and Novec FC4430 and FC4432 manufactured by Sumitomo 3M Limited. Examples of silicone-based surfactants include surfactants having a siloxane bond in the molecule. Specifically, examples of the surfactants include Toray Silicone DC3PA, SH7PA, DC11PA, SH21PA, SH28PA, SH29PA, SH30PA, and SH8400 (trade name: manufactured by Toray Dow Corning Co., Ltd.), KP321, KP322, KP323, KP324, KP326, KP340, and KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF4446, TSF4452, and TSF4460 (manufactured by Momentive Performance Materials Japan, LLC). Examples of the silicone surfactants having fluorine atoms include surfactants having siloxane bonds and fluorocarbon chains in the molecule. Specific examples include Megafac (registered trademark) R08, Megafac BL20, Megafac F475, Megafac F477, and Megafac F443 (manufactured by DIC Corporation).

[0082] In addition to the above, the photoradically polymerizable composition of the present invention may contain various resin additives such as pigments, dyes, diluents, organic or inorganic fillers, leveling agents, surfactants, dispersants, defoamers, thickeners, flame retardants, surface modifiers, penetration promoters, moisture absorbents, moisturizers, fixing agents, antifungal agents, preservatives, antioxidants, ultraviolet absorbers, chelating agents, pH adjusters, stabilizers, lubricants, and plasticizers, within the scope of not impairing the effects of the present invention.

[0083] (Polymerization method) A cured product can be obtained by irradiating the photoradical polymerizable composition of the present invention with light and polymerizing it. For example, when irradiating the photoradical polymerizable composition with light to polymerize and photocure it, the photoradical polymerizable composition can be molded into a film and photocured, or molded into a block and photocured. When molding into a film and photocuring it, the liquid photoradical polymerizable composition is applied to a substrate such as a polyester film using a bar coater or the like so as to have a film thickness of 5 to 300 microns. On the other hand, it can also be applied to a thinner or thicker film thickness by spin coating or screen printing. The vinyl sulfide compound having a heterocycle represented by the general formula (1) of the present invention and its copolymerizable composition have low viscosity, so they may be used as ink for inkjet printing.

[0084] The coating film or droplets of the photoradical polymerizable composition thus prepared are irradiated with energy rays (ultraviolet rays) having a wavelength range of 300 nm to 500 nm at 1 to 1000 mW / cm 2A cured product can be obtained by irradiating light with an intensity of about 100 nm. Examples of light sources used include high pressure mercury lamps, ultra-high pressure mercury lamps, metal halide lamps, xenon lamps, gallium-doped lamps, black lights, 405 nm ultraviolet LEDs, 395 nm ultraviolet LEDs, 385 nm ultraviolet LEDs, 365 nm ultraviolet LEDs, semiconductor lasers, blue LEDs, white LEDs, D bulbs and V bulbs manufactured by Fusion Co., Ltd. In particular, the curing is characterized by being performed even with light of a single wavelength including a long wavelength range such as 365 nm to 405 nm, such as 405 nm ultraviolet LEDs, 395 nm ultraviolet LEDs, 385 nm ultraviolet LEDs, 375 nm ultraviolet LEDs and 365 nm ultraviolet LEDs, and ultraviolet LEDs or semiconductor lasers with central wavelengths of 365 nm, 375 nm, 385 nm, 395 nm and 405 nm are particularly preferred as irradiation sources. EXAMPLES

[0085] Hereinafter, specific embodiments of the present invention will be described in further detail with reference to examples. However, the present invention is not limited to these examples as long as it does not depart from the gist of the present invention.

[0086] (Compound Identification) The identity of the obtained compound was determined using the following instruments. (1) 1 H-NMR analysis: Nuclear magnetic resonance apparatus (NMR), manufactured by JEOL Ltd., model: JNM ECS 400 type FT NMR Spectrator) (2) Mass spectrum: Measured using a mass spectrometer, model GCMS-QP2000, manufactured by Shimadzu Corporation.

[0087] (Physical property measurement of compounds) Measurement of physical properties of the obtained compound (1) Viscosity: E-type viscometer (Toki Sangyo, TVE-35H) (2) Refractive index: Refractometer (measurement conditions: 25°C, n D ) For liquids (1.50≦n D ≦1.70) Model name: ERMA, ER-7MW-H For liquids / films / thin films (1.30≦n D ≦1.70) Model name: Anton Paar Japan, AbbematMw For thin films (n D >1.70) Model name: Atago, DR-M4 (3) Transmittance: SHIMADZU, UV-2600

[0088] (Viscosity measurement of compounds) The viscosity was measured using an E-type viscometer TVE35H. A cone rotor of 1°34'×R24 was used, and after adjusting the gap between the sample cup and the cone rotor, 1.1 mL of sample was injected into the center of the sample cup using a syringe. The sample cup was then set in the viscometer body, and the cone rotor was rotated at 25°C and 20 rpm. The value at which the viscosity became constant was taken as the viscosity value.

[0089] (Refractive index measurement method) Liquid (1.50≦n D ≦1.70), the measurements were performed at 25° C. using a refractometer ER-7MW-H manufactured by ERMA. Liquid / film / thin film (1.30≦n D ≦1.70), measurements were performed at 25°C using AbbematMw manufactured by Anton Paar Japan. Thin film(n D >1.70), measurements were taken at 25°C using an Atago DR-M4.

[0090] (Method of measuring transmittance) The transmittance at 430 nm of the thin film obtained on the glass substrate was measured using a UV-VIS SPECTROPHOTOMETER (Shimazu Corporation, "UV-2600").

[0091] (Method of measuring YI value) As with the transmittance, the YI value was calculated using a UV-VIS SPECTROPHOTOMETER (Shimazu Corporation, "UV-2600") and color measurement software.

[0092] (Tack-free test) As a method for determining whether the radical polymerizable composition of the present invention has been photocured, there is a tack-free test (finger touch test). That is, when the radical polymerizable composition is irradiated with light, it cures and the tack (stickiness) of the surface disappears, so whether it has cured or not is confirmed by whether the tack (stickiness) has disappeared after irradiation with light.

[0093] (UV exposure machine) Model name: MATSUO, UV-LED CURE M / C, JVC-200-SC-N-POWER

[0094] [Synthesis Example 1] 2-mercaptobenzoxazole (50.00g, 0.331mol), 1,2-dibromoethane (124.25g, 0.661mol), and 4-methyltetrahydropyran (500g) were placed in a three-neck flask, stirred and mixed at room temperature, and then heated to 70°C. DBU (diazabicycloundecene, 100.69g, 0.661mol) was then added dropwise, and the mixture was stirred for 3 hours after the addition was complete. The reaction solution was then cooled to room temperature, and the precipitated salt and by-products were removed by vacuum filtration. The organic layer was washed with pure water, dehydrated and filtered with anhydrous magnesium sulfate, and the solvent was removed using an evaporator. After that, vacuum distillation was performed to obtain the target product, 2-vinylthiobenzoxazole, as a colorless, transparent liquid, in an amount of 17.1g and a yield of 29%. D = 1.62, Viscosity (25°C): Approximately 4.2 mPa s. Refractive index and viscosity are listed in Table 3.

[0095] [Synthesis Example 2] 2-mercaptobenzothiazole (37.29g, 0.223mol), 1,2-dibromoethane (83.77g, 0.446mol), and 4-methyltetrahydropyran (186.4g) were placed in a three-necked flask, stirred and mixed at room temperature, and then heated to 70°C. Then, DBU (diazabicycloundecene, 67.89g, 0.446mol) was added dropwise, and the mixture was stirred for 3 hours after the addition was completed. After that, the reaction solution was cooled to room temperature, and the precipitated salt and by-products were removed by vacuum filtration, the organic layer was washed with pure water, dehydrated and filtered with anhydrous magnesium sulfate, and the solvent was removed by an evaporator. Then, vacuum distillation was performed to obtain the target product, 2-vinylthiobenzothiazole, as a pale yellow transparent liquid, with a yield of 9.1g and a yield of 24%. D = 1.69, Viscosity (25°C): Approximately 7.6 mPa s. Refractive index and viscosity are listed in Table 3. [Example 1] Photoradical polymerization of 2-vinylthiobenzoxazole 1 To 100 parts of 2-vinylthiobenzoxazole obtained by the same method as in Synthesis Example 1, 3 parts of OmniradTPO as a photoradical polymerization initiator and 1 part of a fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and dissolved by applying ultrasonic waves. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 365 nm was applied at an illuminance of 100 mW and an exposure dose of 30 Jcm. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n D ) was 1.67, the visible light transmittance was 92%, and the YI value was 3.1. The results are shown in Tables 1 and 2.

[0096] [Example 2] Photoradical polymerization of 2-vinylthiobenzoxazole 2 To 100 parts of 2-vinylthiobenzoxazole obtained by the same method as in Synthesis Example 1, 3 parts of OmniradTPO as a photoradical polymerization initiator and 1 part of a fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and dissolved by applying ultrasonic waves. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 365 nm was applied at an exposure dose of 3 J / cm at an illuminance of 100 mW. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n D ) was 1.67, the visible light transmittance was 92%, and the YI value was 3.5. The results are shown in Table 1.

[0097] [Example 3] Photoradical polymerization of 2-vinylthiobenzoxazole 3 To 100 parts of 2-vinylthiobenzoxazole obtained by the same method as in Synthesis Example 1, 3 parts of OmniradTPO as a photoradical polymerization initiator and 1 part of a fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and dissolved by applying ultrasonic waves. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 365 nm was applied at an exposure dose of 0.3 J / cm with an illuminance of 100 mW. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n D ) was 1.69, the visible light transmittance was 94%, and the YI value was 2.1. The results are shown in Table 1.

[0098] [Example 4] Photoradical polymerization of 2-vinylthiobenzoxazole 4 To 100 parts of 2-vinylthiobenzoxazole obtained by the same method as in Synthesis Example 1, 3 parts of OmniradTPO as a photoradical polymerization initiator and 1 part of a fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and dissolved by applying ultrasonic waves. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 405 nm was applied at an exposure dose of 30 J / cm with an illuminance of 100 mW. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n D ) was 1.67, the visible light transmittance was 94%, and the YI value was 1.9. The results are shown in Table 1.

[0099] [Example 5] Photoradical polymerization of 2-vinylthiobenzoxazole 5 To 100 parts of 2-vinylthiobenzoxazole obtained by the same method as in Synthesis Example 1, 3 parts of OmniradTPO as a photoradical polymerization initiator and 1 part of a fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and dissolved by applying ultrasonic waves. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 405 nm was applied at an exposure dose of 3 J / cm at an illuminance of 100 mW. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n D ) was 1.67, the visible light transmittance was 95%, and the YI value was 1.8. The results are shown in Table 1.

[0100] [Example 6] Photoradical polymerization of 2-vinylthiobenzoxazole 6 To 100 parts of 2-vinylthiobenzoxazole obtained by the same method as in Synthesis Example 1, 3 parts of OmniradTPO as a photoradical polymerization initiator and 1 part of a fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and dissolved by applying ultrasonic waves. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 405 nm was applied at an exposure dose of 0.3 J / cm with an illuminance of 100 mW. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n D ) was 1.68, the visible light transmittance was 95%, and the YI value was 0.3. The results are shown in Table 1.

[0101] [Example 7] Photoradical polymerization of 2-vinylthiobenzothiazole To 100 parts of 2-vinylthiobenzothiazole obtained by the same method as in Synthesis Example 2, 3 parts of OmniradTPO as a photoradical polymerization initiator and 1 part of a fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and dissolved by applying ultrasonic waves. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 365 nm was applied at an exposure dose of 30 J / cm with an illuminance of 100 mW. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.68, and the refractive index after curing (n D The optical transmittance was 70%, and the YI value was 15.5. The results are shown in Tables 1 and 2.

[0102] [Table 1]

[0103] As is clear from Synthesis Examples 1 and 2, Examples 1 to 7, and Table 1, the compounds of the present invention, 2-vinylthiobenzoxazole and 2-vinylthiobenzothiazole, have an extremely low viscosity of 10 mPa·s or less at 25°C, and can be easily polymerized even with light of a single long wavelength such as 365 nm or 405 nm. In addition, the refractive index (n D ) is an ultra-high refractive index of 1.67 to 1.71. In addition, it can be seen that the polymer obtained by curing 2-vinylthiobenzoxazole, in which A in general formula (1) is an oxygen atom, has a YI value of 3.5 to 2.1, which is a low yellowness, and that products cured with low exposure or at a long wavelength of 405 nm in particular tend to show a low YI value of 1.9 to 0.3.

[0104] [Example 8] Photoradical copolymerization of 2-vinylthiobenzoxazole and multifunctional (meth)acrylate 1 50 parts of 2-vinylthiobenzoxazole obtained by the same method as in Synthesis Example 1 and 50 parts of trimethylolpropane triacrylate (TMPTA) were mixed, 3 parts of Omnirad TPO and 1 part of Megafac F-477 were added, and the mixture was dissolved by applying ultrasonic waves. The dissolution rate of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate was extremely fast, and they were easily mixed together to form a uniform liquid phase. Thereafter, the prepared photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 365 nm was applied at 30 J / cm. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.55, and the refractive index after curing (n D ) was 1.59, the visible light transmittance was 97%, and the YI value was 1.7. The results are shown in Table 2.

[0105] [Example 9] Photoradical copolymerization of 2-vinylthiobenzothiazole and multifunctional (meth)acrylate 1 50 parts of 2-vinylthiobenzothiazole obtained by the same method as in Synthesis Example 2 and 50 parts of trimethylolpropane triacrylate (TMPTA) were mixed, 3 parts of OmniradTPO and 1 part of Megafac F-477 were added, and the mixture was dissolved by applying ultrasonic waves. The dissolution rate of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate was extremely fast, and they were easily mixed together to form a uniform liquid phase. Thereafter, the prepared photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 365 nm was applied at 30 J / cm. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.57, and the refractive index after curing (n D ) was 1.62, the visible light transmittance was 87%, and the YI value was 5.5. The results are shown in Table 2.

[0106] [Comparative Example 1] Photoradical polymerization of trimethylolpropane triacrylate (TMPTA) To 100 parts of trimethylolpropane triacrylate (TMPTA), 3 parts of OmniradTPO as a photoradical polymerization initiator and 1 part of fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and dissolved by applying ultrasonic waves. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the inside of the exposure machine with nitrogen, light with a wavelength of 365 nm was applied at an exposure dose of 30 J / cm with an illuminance of 100 mW. 2 The resin was irradiated and cured. After the exposure, the surface was checked for tackiness, and no tackiness was found. The refractive index of the liquid before curing was 1.47, and the refractive index after curing (n D ) was 1.52, the visible light transmittance was 100%, and the YI was 0.2. The results are shown in Tables 2 and 3.

[0107] [Table 2]

[0108] As is clear from Examples 1, 8, 7, and 9, Comparative Example 1, and Table 2, 2-vinylthiobenzoxazole and 2-vinylthiobenzothiazole, which are the compounds of the present invention, form copolymer compositions with trimethylolpropane triacrylate, which is a multifunctional (meth)acrylate, and there is additivity between the refractive index of the copolymer composition and the mixing ratio of the compounds of the present invention. By mixing them in a predetermined ratio, the refractive index (n D It can be seen that the YI value can be set to any value between 1.52 and 1.71. It can also be seen that a copolymer having high transmittance and a low YI value can be obtained by using 2-vinylthiobenzoxazole, in which A in general formula (1) is an oxygen atom.

[0109] [Example 10] Preparation of photoradical copolymerization composition of 2-vinylthiobenzoxazole and multifunctional (meth)acrylate 1 90 parts of 2-vinylthiobenzoxazole obtained by the same method as in Synthesis Example 2 and 10 parts of trimethylolpropane triacrylate (TMPTA) were mixed and dissolved by applying ultrasonic waves. The dissolution rate of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate was extremely fast, and they were easily mixed together to form a uniform liquid phase. The refractive index (n D The molecular weight was 1.60 and the viscosity was 5.1 mPa s. The results are shown in Table 3 and Figure 1.

[0110] [Example 11] Preparation of photoradical copolymerization composition of 2-vinylthiobenzoxazole and multifunctional (meth)acrylate 2 50 parts of 2-vinylthiobenzoxazole obtained in the same manner as in Synthesis Example 2 and 50 parts of trimethylolpropane triacrylate (TMPTA) were mixed and dissolved by applying ultrasonic waves. The dissolution rate of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate was extremely fast, and they were easily mixed together to form a uniform liquid phase. The refractive index (n D The molecular weight was 1.54 and the viscosity was 14.4 mPa s. The results are shown in Table 3 and Figure 1.

[0111] [Example 12] Preparation of photoradical copolymerization composition of 2-vinylthiobenzoxazole and multifunctional (meth)acrylate 3 10 parts of 2-vinylthiobenzoxazole obtained in the same manner as in Synthesis Example 2 and 90 parts of trimethylolpropane triacrylate (TMPTA) were mixed and dissolved by applying ultrasonic waves. The dissolution rate of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate was extremely fast, and they were easily mixed together to form a uniform liquid phase. The refractive index (n D The molecular weight was 1.49 and the viscosity was 65.3 mPa s. The results are shown in Table 3 and Figure 1.

[0112] [Example 13] Preparation of photoradical copolymerization composition of 2-vinylthiobenzothiazole and multifunctional (meth)acrylate 1 90 parts of 2-vinylthiobenzothiazole obtained in the same manner as in Synthesis Example 2 and 10 parts of trimethylolpropane triacrylate (TMPTA) were mixed and dissolved by applying ultrasonic waves. The dissolution rate of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate was extremely fast, and they were easily mixed together to form a uniform liquid phase. The refractive index (n D The molecular weight was 1.66 and the viscosity was 9.3 mPa s. The results are shown in Table 3 and Figure 2.

[0113] [Example 14] Preparation of photoradical copolymerization composition of 2-vinylthiobenzothiazole and multifunctional (meth)acrylate 2 50 parts of 2-vinylthiobenzothiazole obtained in the same manner as in Synthesis Example 2 and 50 parts of trimethylolpropane triacrylate (TMPTA) were mixed and dissolved by applying ultrasonic waves. The dissolution rate of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate was extremely fast, and they were easily mixed together to form a uniform liquid phase. The refractive index (n D The molecular weight was 1.57 and the viscosity was 24.8 mPa s. The results are shown in Table 3 and Figure 2.

[0114] [Example 15] Preparation of photoradical copolymerization composition of 2-vinylthiobenzothiazole and multifunctional (meth)acrylate 3 10 parts of 2-vinylthiobenzothiazole obtained in the same manner as in Synthesis Example 2 and 90 parts of trimethylolpropane triacrylate (TMPTA) were mixed and dissolved by applying ultrasonic waves. The dissolution rate of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate was extremely fast, and they were easily mixed together to form a uniform liquid phase. The refractive index (n D The molecular weight was 1.49 and the viscosity was 71.6 mPa s. The results are shown in Table 3 and Figure 2.

[0115] [Table 3]

[0116] As is clear from Table 3, Synthesis Examples 1 and 2, Examples 10 to 15, and Comparative Example 1, the compounds of the present invention, 2-vinylthiobenzoxazole and 2-vinylthiobenzothiazole, are easily dissolved and mixed with trimethylolpropane triacrylate, a multifunctional (meth)acrylate, in any composition to form a copolymer composition. D As is clear from Figures 1 and 2, there is an additivity between the composition ratio and the refractive index, and it is possible to adjust the refractive index of the composition. In addition, in terms of adjusting the viscosity, the viscosity reducing effect of the amount of 2-vinylthiobenzoxazole or 2-vinylthiobenzothiazole, which is the compound of the present invention, added to a copolymer composition of 2-vinylthiobenzoxazole or 2-vinylthiobenzothiazole, which is the compound of the present invention, and trimethylolpropane triacrylate, which is a multifunctional (meth)acrylate, is large, and the viscosity of the copolymer composition can be significantly reduced by adding a small amount. For example, in an example using 2-vinylthiobenzoxazole and trimethylolpropane triacrylate, it is understood from Figure 1 that in order to prepare a copolymerizable composition with a viscosity of 30 mPa·s or less at 25°C, it can be achieved by setting the amount of 2-vinylthiobenzoxazole to 32 wt% or more.

Claims

1. (A) a vinyl sulfide compound having a heterocycle represented by general formula (1), (B) a radically polymerizable compound having a (meth)acrylic group, (C) a photoradical polymerization initiator, A photoradical polymerizable composition comprising: The refractive index (n Ｄ ) is 1.50 or more. 【Chemistry 1】 (In the general formula (1), A represents an oxygen atom or a sulfur atom, and R １ , R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or an arylthio group having 6 to 10 carbon atoms; R １ and R ２ may be bonded to each other to form a saturated or unsaturated ring.

2. 2. The photoradically polymerizable composition according to claim 1, wherein the viscosity of the photoradically polymerizable composition at 25[deg.] C. is 30 mPa.s or less.

3. The photoradical polymerizable composition according to claim 1, characterized in that the (B) radically polymerizable compound having a (meth)acrylic group is at least one radically polymerizable compound selected from the group consisting of monofunctional (meth)acrylates, monofunctional (meth)acrylamides, polyfunctional (meth)acrylates, and polyfunctional (meth)acrylamides.

4. The photoradical polymerizable composition according to claim 1, characterized in that the photoradical polymerization initiator (C) is one or more photoradical polymerization initiators selected from the group consisting of alkylphenone-based photoradical polymerization initiators, benzophenone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, oxime ester-based photoradical polymerization initiators, α-aminoacetophenone-based photoradical polymerization initiators, biimidazole-based photoradical polymerization initiators, triazine-based photoradical polymerization initiators, and thioxanthone-based photoradical polymerization initiators.

5. 2. The photoradically polymerizable composition according to claim 1, wherein the content of the vinyl sulfide compound having a heterocycle represented by general formula (1) (A) is 10% by weight or more, based on 100% by weight of the total amount of the photoradically polymerizable composition.

6. A polymerization method comprising irradiating the photoradically polymerizable composition according to claim 1 with active energy rays.

7. 7. The polymerization method according to claim 6, wherein the active energy rays to be irradiated have a peak wavelength in the wavelength range of 350 nm to 420 nm.

8. A polymer obtained by polymerizing the photoradical polymerizable composition according to any one of claims 1 to 5, wherein the polymer has a refractive index (n Ｄ ) is 1.50 or more.

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