Photoradically polymerizable composition containing vinyl sulfide compound having heterocyclic ring

Abstract

[Problem] To provide a photoradically polymerizable composition that is to be used as a transparent resin material suitable for optical applications, that not only has excellent curability but also has a high refractive index at a low viscosity, and that, when being cured, provides a polymer in which the refractive index is adjustable. [Solution] This photoradically polymerizable composition contains (A) a vinyl sulfide compound having a heterocyclic ring represented by general formula (1), (B) a radically polymerizable compound having a (meth)acrylic group, and (C) a photoradical polymerization initiator. The photoradically polymerizable composition is characterized by having a refractive index (nD) of 1.50 or more. (In 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.)

Description

Photoradical polymerizable composition containing a vinyl sulfide compound having a heterocycle

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

[0002] In recent years, displays using liquid crystal or organic electroluminescence (EL) have become widely used. The surfaces of these displays are covered with a laminate of multiple optical films, providing functions such as light extraction and touch panel functionality. Furthermore, 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 coming from the outside and the light emitted from the inside is extremely important in terms of display quality.

[0003] On the other hand, these film laminates each have a different refractive index relative to light, and these differences in refractive index can result in various characteristics or, conversely, various problems. For example, in color filters, different pigment species result in different refractive indices for the pixels, leading to problems such as increased light scattering at the interface with the overcoat layer and loss of transmitted light. Furthermore, film laminates are generally bonded using adhesive compositions, but it is known that using a typical acrylic adhesive to bond high-refractive-index materials can cause reflection at the interface due to the difference in refractive index between the two materials. For this reason, refractive index adjusters are often used to adjust the refractive index of the adhesive. For example, Patent Document 1 describes the development of an adhesive with a high refractive index of 1.55 or higher by adding a compound having a triazine ring to an acrylic polymer.

[0004] Furthermore, when a gas barrier film is used to protect the surface of a display, there are two interfaces between the plastic substrate, the vapor-deposited thin film layer, and the gas barrier coating layer, which causes color unevenness due to interference light, resulting in appearance problems. Generally, when two films are stacked, the greater the difference in refractive index between them, the greater the reflection at the film contact surface, which is thought to cause problems with light extraction. Therefore, methods to reduce the refractive index difference between the stacked films are being investigated. For example, in touch panels, films patterned with a metal oxide called ITO (indium tin oxide), which transmits visible light, are used. However, since ITO is an inorganic material, it has a higher light reflectance than organic materials, and the difference in reflectance between the ITO surface and the substrate film (PET) causes the ITO pattern to become visible. As such, resin films generally have a low refractive index, and attempts to increase the refractive index of the film are being investigated. 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 is obtained having a refractive index at 589 nm of 1.557 or more and 1.571 or less. Thus, there is a demand for a refractive index modifier that can increase the refractive index of existing polymerizable compositions.

[0005] In general, there is a positive correlation between the refractive index of a film and the refractive index of the polymerizable composition that is its raw material, 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 thought that a high refractive index can be achieved by adding a polymerizable compound with a high refractive index that is copolymerizable with an existing polymerizable compound.

[0006] Methods for increasing the refractive index of polymerizable compounds include introducing an aromatic ring into the molecular structure, or introducing a halogen atom (excluding fluorine) or a sulfur atom. For example, polymerizable compounds having an aromatic ring in the molecular structure include those having a benzene ring as well as polycyclic aromatic rings such as biphenyl, naphthalene, fluorene, and anthracene. However, polymerizable compounds having a single benzene ring in the molecular structure do not have a sufficient refractive index. Furthermore, while polymerizable compounds having a polycyclic aromatic ring such as biphenyl, naphthalene, fluorene, and anthracene in the molecular structure are expected to have a high refractive index, they often become high-viscosity liquids or crystalline solids, resulting in problems such as poor handling properties, such as poor solubility. For example, Patent Document 3 discloses a composition containing a (meth)acrylate having a fluorene skeleton as a curable composition capable of producing a cured product with 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, monomer compositions containing sulfur atoms with high intrinsic refractive indices have also been reported. For example, Patent Document 4 attempts to increase the refractive index by introducing an aromatic ring via a sulfur atom. Patent Document 5 discloses a polymerizable composition primarily composed of a thio(meth)acrylate monomer, including bis[(4-methacryloylthio)phenyl] sulfide. Patent Document 6 also discloses a compound containing a methylthiophenyl group as a novel (meth)acrylic acid ester for dilution, which has low viscosity, a high refractive index, and a homopolymer with high heat resistance. Patent Document 7 discloses a liquid curable ink composition capable of forming a cured product with a high refractive index and suitable for inkjet printing, which uses a (meth)acrylate compound containing a sulfide compound and a sulfur compound, and zirconium oxide nanocrystals as the metal compound nanocrystals.

[0008] Furthermore, Patent Document 8 discloses a (meth)acrylic acid ester having a fused 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 polymerizable compounds 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 symmetric (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 high refractive index acrylic esters 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. Disclosed aromatic heterocycles include 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. Among these, a thiazolothiadiazole ring is disclosed.

[0010] However, most of these high refractive index polymerizable compounds have an acrylate ester structure. By using acrylate esters, transparency and high polymerizability can be expected. However, on the other hand, there is a drawback in that the viscosity becomes high. For example, Patent Document 12 discloses high refractive index monomers that are UV-curable and useful for the production of optical articles, particularly light-controlling films, and among them, heterocyclic (meth)acrylates such as meth)acrylates having a benzothiazole group are disclosed. It is described that 1,3-bis(2-mercaptobenzothiazoyl)propan-2-yl acrylate has a refractive index of 1.629 and a viscosity of 860 cP, and that 2-(4-chlorophenoxy)-1-[(phenylthio)methyl]ethyl acrylate has a refractive index of 1.5792 and a viscosity of 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, their use in coating methods such as inkjet printing has been seen as promising, and low viscosity is also an important factor required for polymerizable compositions containing these high refractive index polymerizable compounds as inkjet inks. For example, as inkjet inks, polymerizable compositions with low viscosity, such as 30 mPa s or less, are required, and polymerizable compounds with 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, as a composition for nanoimprints, a compound having a polymerizable functional group and a diaryl sulfide skeleton, and discloses that the polymerizable functional group is a vinyl group, an allyl group, a methacryloyl group, or an acryloyl 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 radically polymerizable compound such as 2-vinylthiobenzothiazole and divinylbenzene as a plastic lens material 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 electroluminescent material. Both of these methods use a thermal radical polymerization initiator, but their compositions differ from those of the present invention.

[0014] JP 2023-38116 A JP 2012-72316 A JP 2019-14767 A JP 2020-37693 A JP 9-25321 A JP 2017-190326 A JP 2021-31669 A JP 2018-104696 A JP 2012-82145 A JP 2023-32499 Patent Publication No. 2017-14213 Patent Publication No. 2005-133071 Patent Publication No. 2022-170092 Patent Publication No. 2022-128911 International Publication No. 2018 / 062196 Pamphlet Patent Publication No. 2021-55051 Patent Publication No. 2-265907 Patent Publication No. 4-225007 Patent Publication No. 2000-87027

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

[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 be used to form a copolymer composition with various radical 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]

[0019] 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.

[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 photoradical polymerizable composition according to the first invention, characterized in that (B) the radical polymerizable compound having a (meth)acrylic group is at least one radical 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 the photoradical polymerizable composition according to the first invention, characterized in that the content of (A) the vinyl sulfide compound having a heterocycle represented by general formula (1) is 10% by weight or more, relative to 100% by weight of the total amount of the photoradical polymerizable composition.

[0024] A sixth aspect of the present invention resides in a polymerization method comprising irradiating the photoradical 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, wherein the refractive index (n Ｄ ) is 1.50 or more.

[0027] In the present invention, (meth)acrylate refers to acrylate or methacrylate, (meth)acryloyl refers to acryloyl or methacryloyl, and (meth)acrylic refers to acrylic or methacrylic. Furthermore, unless otherwise specified, the refractive index in the present invention refers to 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.

[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. By polymerizing the photoradical polymerizable composition of the present invention, a polymer having a very high refractive index can be obtained.

[0029] The objects, features and advantages of the present invention will become more apparent from the following detailed description.

[0030] 1 is a diagram showing the relationship between the addition ratio of 2-vinylthiobenzoxazole in a copolymer composition of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate and the refractive index and viscosity of the composition. The smooth line is a line that smoothly connects each of the plotted points. 2 is a diagram showing the relationship between the addition ratio of 2-vinylthiobenzothiazole in a copolymer composition of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate and the refractive index and viscosity of the composition. The smooth line is a line that smoothly connects each of the plotted points.

[0031] The present invention will be described in detail below.

[0032] (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).

[0033]

[0034] 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.

[0035] In general formula (1), R １ , R ２The alkyl group having 1 to 6 carbon atoms represented by the formula (I) may be a linear alkyl group or a branched alkyl group. Specific examples 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.

[0036] Examples of aryl groups having 6 to 10 carbon atoms include phenyl, tolyl, and naphthyl groups, which may have a substituent. Examples of alkoxy groups having 1 to 6 carbon atoms include linear, branched, and cyclic alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, pentoxy, hexyloxy, and cyclohexyloxy. Examples of aryloxy groups having 6 to 10 carbon atoms include phenyloxy, tolyloxy, and naphthyloxy groups, which may have a substituent. Examples of alkylthio groups having 1 to 6 carbon atoms include methylthio, ethylthio, n-propylthio, i-propylthio, n-butylthio, i-butylthio, n-amylthio, i-amylthio, n-hexylthio, and cyclohexylthio. Examples of arylthio groups having 6 to 10 carbon atoms include phenylthio and naphthylthio.

[0037] 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.

[0038] Specific examples of the vinyl sulfide compound having a benzoxazole group in which A in 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.

[0039] Specific examples of vinyl sulfide compounds having a benzothiazole group in which A in 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.

[0040] 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. Furthermore, compounds in which A in general formula (1) is an oxygen atom are preferred in terms of being polymerized at a low exposure dose and the resulting polymer has high transmittance and low yellowness, and 2-vinylthiobenzoxazole of structural formula (2) is particularly preferred in terms of ease of synthesis.

[0041]

[0042]

[0043] (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, the compound of general formula (1) can be synthesized by reacting a 2-mercaptobenzoxazole compound or a 2-mercaptobenzothiazole compound with a dihalogenated ethane such as 1,2-dibromoethane in the presence of a base, followed by dehydrohalogenation in the presence of a base.

[0044]

[0045] In Reaction Scheme 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 Xs may be the same or different.

[0046] Usually, the reaction of the compound of general formula (4) with dihalogenated ethane causes 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 target vinyl sulfide compound having a heterocycle of general formula (1) can be obtained without isolating the intermediate.

[0047] The heterocyclic vinyl sulfide represented by general formula (1) synthesized by the above method is a compound with extremely low viscosity and high refractive index. For example, 2-vinylthiobenzoxazole, which is a vinyl sulfide with a heterocyclic ring of the present invention, is a liquid compound with an extremely low viscosity of 4.2 mPa·s at 25°C and a high refractive index of 1.62. 2-vinylthiobenzothiazole is also a liquid compound with an extremely low viscosity of 7.6 mPa·s at 25°C and a very high refractive index of 1.68.

[0048] Furthermore, the vinyl sulfide having a heterocycle represented by general formula (1) of the present invention can be polymerized and cured using commercially available photoradical polymerization initiators. It is an extremely useful polymerizable compound that can be polymerized and cured not only with light sources such as high-pressure mercury lamps, but also with single-wavelength light sources with low irradiation energy, such as ultraviolet LEDs and semiconductor lasers. It also has extremely high compatibility with other polymerizable compounds such as (meth)acrylic acid esters. The photoradical polymerizable composition obtained by mixing it also maintains low viscosity, and the resulting polymerized and cured product exhibits a high refractive index. In terms of a high refractive index, 2-vinylthiobenzothiazole is preferred. Furthermore, 2-vinylthiobenzoxazole is particularly preferred because it polymerizes with low exposure doses, and its polymer exhibits an ultra-high refractive index, high transmittance, and low YI (yellowing index).

[0049] (B) Radically Polymerizable Compound Having a (Meth)acrylic Group The vinyl sulfide compound having a heterocycle represented by general formula (1) of the present invention is compatible with various radically polymerizable compounds and can form a copolymerizable composition. Examples include vinyl ether, vinyl sulfide (excluding vinyl sulfide having a heterocycle represented by general formula (1)), (meth)acrylic acid, (meth)acrylonitrile, monofunctional (meth)acrylate, monofunctional (meth)acrylamide, polyfunctional (meth)acrylate, polyfunctional (meth)acrylamide, and oligomers thereof. Among these radically polymerizable compounds, radically polymerizable compounds having a Q value of 0.9 or less are preferred, and radically polymerizable compounds having a (meth)acrylic group are particularly preferred in terms of practicality such as transparency. These radically polymerizable compounds are preferably used in combination with the radically polymerizable compound and in a mixing ratio such that the viscosity at 25°C of a 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.

[0050] The radically polymerizable compound having a (meth)acrylic group is preferably a monofunctional (meth)acrylate, a monofunctional (meth)acrylamide, a polyfunctional (meth)acrylate, or a polyfunctional (meth)acrylamide. Examples of usable monofunctional (meth)acrylates 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 ... methyl (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.

[0051] 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.

[0052] 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 monomer 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 to C6, linear or branched) (meth)acrylates are preferably used.

[0053] 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.

[0054] 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.

[0055] Examples of the acetoacetyl group-containing (meth)acrylic monomer include 2-(acetoacetoxy)ethyl (meth)acrylate.

[0056] Examples of the isocyanate group-containing (meth)acrylic monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

[0057] 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.

[0058] 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, benzylphenyl (meth)acrylate, p-phenylbenzyl acrylate, p-t-butylphenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxydiethylene 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 monomer include (meth)acrylic monomers having a naphthalene ring group, such as 4-methoxy-1-naphthoxyethyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, and 2-naphthylmethyl acrylate; (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 fluorenyl (meth)acrylate and 9-fluorenylmethyl (meth)acrylate (9-(meth)acryloyloxymethylfluorene). In addition to the compounds exemplified here, examples include (meth)acrylic monomers having, as aromatic hydrocarbon groups, 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 a high viscosity. By forming a copolymer composition with a vinyl sulfide having a heterocycle represented by general formula (1) of the present invention, a photoradical polymerizable composition having a high refractive index but a low viscosity can be obtained.

[0059] 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-hydroxyalkyl (C1 to C18, linear or branched) (meth)acrylamides, and N-hydroxyalkyl (C1 to C18). Examples of suitable monofunctional monomers include N-(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, diacetoneacrylamide, N-(dimethylamino)propyl(meth)acrylamide, and N-hydroxyethylacrylamide are more preferred. These monofunctional monomers may be used alone or in combination of two or more.

[0060] 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, cyclohexanedimethanol di(meth)acrylate, acrylate ester (dioxane glycol diacrylate), alkoxylated hexanediol di(meth)acrylate, alkoxylated cyclohexanedimethanol di(meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and other monomers and oligomers.From the viewpoint of easy availability as a commercially available product, examples of polyfunctional (meth)acrylates include, for example, CN2203 and CN2270 manufactured by SARTOMER Co., Ltd., and M-6100 and M-8060 manufactured by Toagosei Co., Ltd.; examples of urethane acrylates include, for example, UV-3200B, UV-3000B, UV-6640B, UV-3700B, UV-3310B, and UV-7000B manufactured by Nippon Synthetic Chemical Industry Co., Ltd.; U-4HA and U-200PA manufactured by Shin-Nakamura Chemical Co., Ltd.; and EBECRYL245, EBECRYL1259, and EBECRYL245 manufactured by Daicel-Cytec Co., Ltd. Examples of epoxy (meth)acrylates that can be used include ECRYL8210, EBECRYL284, EBECRYL8402, SARTOMER products under the trade names CN944, CN969, CN9002, and CN9029, Negami Chemical Industrial Co., Ltd. products under the trade names UN1255 and UN-5507, and Kyoeisha Chemical Co., Ltd. products under the trade names AH-600 and UA-306I. Examples of epoxy (meth)acrylates that can be used include Daicel-Cytec products under the trade names EBECRYL1259, EBECRYL605, and EBECRYL1606, and SARTOMER products under the trade names CN110, CN120, and CN153. Furthermore, from the viewpoint of the viscosity of the resin composition, ease of handling, and the like, urethane acrylate UV-6640B or U-200PA is more preferred. These polyfunctional (meth)acrylates may be used singly or in combination of two or more.

[0061] Examples of polyfunctional (meth)acrylamides include methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide, diallyl(meth)acrylamide, and urethanedi(meth)acrylamide.

[0062] In the photoradical polymerizable composition of the present invention, the radical 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.

[0063] 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 viewpoint of achieving a low viscosity and a high refractive index, the content is more preferably 10% by weight or more, and even more preferably 20% by weight or more.

[0064] In the photoradical polymerizable composition of the present invention, compositions with various refractive indices and viscosities can be prepared by adjusting the compositional ratio of (A) the vinyl sulfide compound having a heterocycle represented by general formula (1) and (B) the radically polymerizable compound having a (meth)acrylic group. A preferred compositional ratio is selected to obtain the desired refractive index and viscosity. For example, in an example where 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 radically polymerizable compound having a (meth)acrylic group, it can be seen from Figure 1 that a copolymerizable composition with a viscosity of 30 mPa·s or less at 25°C can be prepared by adding 2-vinylthiobenzoxazole in an amount of 32 wt% or more.

[0065] ((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., a compound that absorbs light energy and decomposes and / or reacts to generate radicals. It also refers to a compound that generates radicals when heated, i.e., a compound that absorbs thermal energy and decomposes to generate radical species. For example, peroxide-based radical polymerization initiators or azo-based radical polymerization initiators are not included in the photoradical polymerization initiator of the present invention. Any commonly used photoradical polymerization initiator can be used without any particular limitation. For example, 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.

[0066] 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, and 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, N,N-dimethylaminoacetophenone, and the like.

[0067] Examples of the benzophenone-based photoradical polymerization initiator include benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone.

[0068] Examples of the acylphosphine oxide-based photoradical polymerization initiator include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (trade name "Omnirad TPO" manufactured by IGM Group B.V.) and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad 819" manufactured by IGM Group B.V.).

[0069] Examples of the oxime ester photoradical polymerization initiator 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-acetyl [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 Corporation), and the like.

[0070] Examples of the α-aminoacetophenone-based photoradical polymerization initiator include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (trade name "Omnirad 907" manufactured by IGM Group B.V.), 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (trade name "Omnirad 369" manufactured by IGM Group B.V.), and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholino-4-yl-phenyl)butan-1-one (trade name "Omnirad 379" manufactured by IGM Group B.V.).

[0071] 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.

[0072] 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.

[0073] Examples of the thioxanthone-based photoradical polymerization initiator include 2,4-diethylthioxanthone and 2-isopropylthioxanthone.

[0074] The alkylphenone-based photoradical polymerization initiator, benzophenone-based photoradical polymerization initiator, acylphosphine oxide-based photoradical polymerization initiator, oxime ester-based photoradical polymerization initiator, α-aminoacetophenone-based photoradical polymerization initiator, biimidazole-based photoradical polymerization initiator, triazine-based photoradical polymerization initiator, and thioxanthone-based photoradical polymerization initiator that can be used in the present invention can be used alone or in combination of two or more types depending on the application, etc.

[0075] Among the photoradical polymerization initiators listed above, biimidazole-based photoradical polymerization initiators, alkylphenone-based photoradical polymerization initiators, acylphosphine oxide-based photoradical polymerization initiators, and oxime-based photoradical polymerization initiators are preferred, with acylphosphine oxide-based photoradical polymerization initiators and oxime ester-based photoradical polymerization initiators being particularly preferred in terms of activity.

[0076] 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.

[0077] (Photoradical Polymerization Sensitizer) High-pressure mercury lamps have traditionally been used as light sources in photoradical polymerization. However, due to issues such as their high energy consumption, curing devices using LED light sources have become more popular due to their low running costs and environmental impact. However, these LED light sources emit long-wavelength light, such as those with central wavelengths of 365 nm, 385 nm, 395 nm, or 405 nm. Unlike high-pressure mercury lamps, LED light emits light with a single wavelength, resulting in weak irradiation energy. Such LED lamps often fail to sufficiently cure products using conventional photoradical polymerization initiators. To accommodate such long-wavelength, single-beam LED lamps, it is preferable to further add a photoradical polymerization sensitizer. The addition of a photoradical polymerization sensitizer that absorbs long-wavelength light promotes the radical generation reaction of the photoradical polymerization initiator, thereby improving the reactivity of radical polymerization.

[0078] The photoradical polymerization sensitizer can be any commonly used one that is active to light of the irradiation wavelength and is not particularly limited. 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] Furthermore, the photoradical polymerizable composition of the present invention may contain a surfactant, preferably a nonionic surfactant. The inclusion of a nonionic surfactant improves the coatability of the radical polymerizable composition when applied to a substrate to obtain a resin film, enabling the production of a coating film of uniform thickness. Nonionic surfactants include, for example, compounds containing fluorine groups (e.g., fluorinated alkyl groups) or silanol groups, or compounds with a siloxane bond as their main skeleton. It is preferable to use those 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. Silicone-based surfactants include surfactants containing siloxane bonds within the molecule. Specific examples include Toray Silicone DC3PA, SH7PA, DC11PA, SH21PA, SH28PA, SH29PA, SH30PA, and SH8400 (trade names: manufactured by Dow Corning Toray Co., Ltd.), KP321, KP322, KP323, KP324, KP326, KP340, and KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), and TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF4446, TSF4452, and TSF4460 (manufactured by Momentive Performance Materials Japan, LLC). Examples of silicone surfactants having fluorine atoms include surfactants having a siloxane bond and a fluorocarbon chain in the molecule. Specific examples include Megafac (registered trademark) R08, Megafac BL20, Megafac F475, Megafac F477, and Megafac F443 (manufactured by DIC Corporation).

[0083] In addition to the above, the photoradical polymerizable composition of the present invention may contain various resin additives such as pigments, dyes, diluents, organic or inorganic fillers, leveling agents, surfactants, dispersants, antifoaming agents, thickeners, flame retardants, surface modifiers, penetration enhancers, moisture absorbers, humectants, fixing agents, antifungal agents, preservatives, antioxidants, ultraviolet absorbers, chelating agents, pH adjusters, stabilizers, lubricants, and plasticizers, as long as the effects of the present invention are not impaired.

[0084] (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 it can be molded into a block and photocured. When molded into a film and photocured, the liquid photoradical polymerizable composition is applied to a substrate such as a polyester film using a bar coater or the like to a film thickness of 5 to 300 microns. Alternatively, it can be applied to a thinner or thicker film thickness by spin coating or screen printing. The vinyl sulfide compound having a heterocycle represented by general formula (1) of the present invention and its copolymerizable composition have low viscosity, and therefore can be used as an ink for inkjet printing.

[0085] 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 at an intensity of about 100 nm. Examples of light sources that can be 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, Inc. In particular, the curing can be achieved even with light of a single wavelength including a long wavelength range of 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 center wavelengths of 365 nm, 375 nm, 385 nm, 395 nm, or 405 nm are particularly preferred as irradiation sources.

[0086] Specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist of the invention. That is, the following examples are not intended to be exhaustive or to limit the present invention to the exact form described. Therefore, the present invention is not limited to the following described examples unless it exceeds the gist of the invention. Furthermore, unless otherwise specified, all parts and percentages are by weight.

[0087] (Identification of Compound) The identification of the obtained compound was measured using the following equipment: (1) １ H-NMR analysis: Nuclear magnetic resonance apparatus (NMR), manufactured by JEOL Ltd., Model: JNM ECS 400 FT NMR Spectrometer) (2) Mass spectrum: Measured using a mass spectrometer, Model GCMS-QP2000, manufactured by Shimadzu Corporation.

[0088] (Measurement of physical properties of compound) 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 ) In the case of liquids (1.50≦n Ｄ ≦1.70) Model name: ERMA, ER-7MW-H ・Liquid / film / thin film (1.30≦n Ｄ≦1.70) Model name: Anton Paar Japan, AbbematMw ・In the case of thin films (n Ｄ >1.70) Model name: Atago, DR-M4 (3) Transmittance: SHIMADZU, UV-2600

[0089] (Viscosity Measurement of Compound) The viscosity was measured using an E-type viscometer TVE35H. A cone rotor of 1°34' x 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.

[0090] (Refractive index measurement method) Liquid (1.50≦n Ｄ ≦1.70), the measurement was carried out at 25°C using a refractometer ERMA ER-7MW-H. Ｄ ≦1.70), the measurement was performed at 25°C using Abbemat Mw manufactured by Anton Paar Japan. Ｄ >1.70), measurements were taken at 25°C using a DR-M4 manufactured by Atago Co., Ltd.

[0091] (Method for 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").

[0092] (Method of Measuring YI Value) As with the transmittance, the YI value was calculated using a UV-VIS SPECTROPHOPHOTOMETER (Shimazu Corporation, "UV-2600") and color measurement software.

[0093] (Tack-Free Test) A method for determining whether the radical polymerizable composition of the present invention has been photocured is the tack-free test (touch test). That is, when the radical polymerizable composition is irradiated with light, it cures and the tack (stickiness) of the surface disappears, and whether it has been cured or not is confirmed by whether the tack (stickiness) has disappeared after light irradiation.

[0094] (UV exposure machine) Model name: MATSUO, UV-LED CURE M / C, JVC-200-SC-N-POWER

[0095] Synthesis Example 1: 2-mercaptobenzoxazole (50.00 g, 0.331 mol), 1,2-dibromoethane (124.25 g, 0.661 mol), and 4-methyltetrahydropyran (500 g) were placed in a three-neck flask and stirred at room temperature, then heated to 70°C. Then, DBU (diazabicycloundecene, 100.69 g, 0.661 mol) was added dropwise, and the mixture was stirred for 3 hours after the addition was complete. The reaction mixture 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 over anhydrous magnesium sulfate, filtered, and the solvent was removed using an evaporator. Vacuum distillation was then carried out to obtain the target product, 2-vinylthiobenzoxazole, as a colorless, transparent liquid, in a yield of 17.1 g and 29%. Ｄ = 1.62, Viscosity (25°C): about 4.2 mPa·s. The refractive index and viscosity are shown in Table 3.

[0096] Synthesis Example 2: 2-mercaptobenzothiazole (37.29 g, 0.223 mol), 1,2-dibromoethane (83.77 g, 0.446 mol), and 4-methyltetrahydropyran (186.4 g) were placed in a three-necked flask and stirred at room temperature, then heated to 70°C. Then, DBU (diazabicycloundecene, 67.89 g, 0.446 mol) was 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 over anhydrous magnesium sulfate, filtered, and the solvent was removed using an evaporator. Vacuum distillation was then carried out to obtain the target product, 2-vinylthiobenzothiazole, as a pale yellow, transparent liquid, in a yield of 9.1 g and 24%. Ｄ= 1.69, viscosity (25°C): approximately 7.6 mPa·s. The refractive index and viscosity are shown 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 Omnirad TPO as a photoradical polymerization initiator and 1 part of fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and the mixture was dissolved by applying ultrasound. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, it was exposed to light of 365 nm wavelength at an illuminance of 100 mW and an exposure dose of 30 Jcm. ２ The surface was checked for tackiness after exposure and found to be tacky. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n Ｄ The transmittance of visible light was 92%, and the YI value was 3.1. The results are shown in Tables 1 and 2.

[0097] 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 Omnirad TPO as a photoradical polymerization initiator and 1 part of the fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and the mixture was dissolved by applying ultrasound. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, it was exposed to light of 365 nm wavelength at an illuminance of 100 mW and an exposure dose of 3 J / cm. ２ The surface was checked for tackiness after exposure and found to be tacky. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n Ｄ The transmittance of visible light was 92%, and the YI value was 3.5. The results are shown in Table 1.

[0098] 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 Omnirad TPO as a photoradical polymerization initiator and 1 part of the fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and the mixture was dissolved by applying ultrasound. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, it was exposed to light of 365 nm wavelength at an illuminance of 100 mW and an exposure dose of 0.3 J / cm. ２ The surface was checked for tackiness after exposure and found to be tacky. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n Ｄ The transmittance of visible light was 94%, and the YI value was 2.1. The results are shown in Table 1.

[0099] 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 Omnirad TPO as a photoradical polymerization initiator and 1 part of the fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and the mixture was dissolved by applying ultrasound. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, it was exposed to light with a wavelength of 405 nm at an illuminance of 100 mW and an exposure dose of 30 J / cm. ２ The surface was checked for tackiness after exposure and found to be tacky. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n Ｄ The transmittance of visible light was 94%, and the YI value was 1.9. The results are shown in Table 1.

[0100] 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 Omnirad TPO as a photoradical polymerization initiator and 1 part of the fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and the mixture was dissolved by applying ultrasound. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, it was exposed to light with a wavelength of 405 nm at an illuminance of 100 mW and an exposure dose of 3 J / cm. ２ The surface was checked for tackiness after exposure and found to be tacky. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n Ｄ The transmittance of visible light was 95%, and the YI value was 1.8. The results are shown in Table 1.

[0101] 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 Omnirad TPO as a photoradical polymerization initiator and 1 part of the fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and the mixture was dissolved by applying ultrasound. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, it was exposed to light with a wavelength of 405 nm at an illuminance of 100 mW and an exposure dose of 0.3 J / cm. ２ The surface was checked for tackiness after exposure and found to be tacky. The refractive index of the liquid before curing was 1.62, and the refractive index after curing (n Ｄ The visible light transmittance was 95%, and the YI value was 0.3. The results are shown in Table 1.

[0102] 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 Omnirad TPO as a photoradical polymerization initiator and 1 part of the fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added, and the mixture was dissolved by applying ultrasound. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, it was exposed to light of 365 nm wavelength at an illuminance of 100 mW and an exposure dose of 30 J / cm. ２ The surface was checked for tackiness after exposure and found to be tacky. The refractive index of the liquid before curing was 1.68, and the refractive index after curing (n Ｄ The visible light transmittance was 70% and the YI value was 15.5. The results are shown in Tables 1 and 2.

[0103]

[0104] 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, can be easily polymerized even with light of a single long wavelength such as 365 nm or 405 nm, and the obtained polymers have a refractive index (n Ｄ It can be seen that the refractive index is extremely high, ranging from 1.67 to 1.71. It can also 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 low in yellowness, and that products cured with low exposure doses or at a long wavelength of 405 nm tend to have low YI values ​​of 1.9 to 0.3.

[0105] Example 8 Photoradical Copolymerization of 2-Vinylthiobenzoxazole and Polyfunctional (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, and 3 parts of Omnirad TPO and 1 part of Megafac F-477 were added, followed by sonication to dissolve. The dissolution rate of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate was extremely fast, and they easily mixed to form a homogeneous 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 atmosphere inside the exposure machine with nitrogen, light of 365 nm wavelength was irradiated at 30 J / cm. ２ The resin was irradiated and cured. After the exposure, the surface was checked for tackiness and found to be tacky. The refractive index of the liquid before curing was 1.55, and the refractive index after curing (n Ｄ The transmittance of visible light was 97%, and the YI value was 1.7. The results are shown in Table 2.

[0106] Example 9 Photoradical Copolymerization of 2-Vinylthiobenzothiazole and Polyfunctional (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, and 3 parts of Omnirad TPO and 1 part of Megafac F-477 were added, followed by dissolution by applying ultrasound. The dissolution rate of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate was extremely fast, and they easily mixed to form a homogeneous liquid phase. Thereafter, the prepared photoradical polymerizable composition was formed into a film having a thickness of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, the film was exposed to light of 365 nm wavelength at 30 J / cm. ２ The resin was irradiated and cured. After the exposure, the surface was checked for tackiness and found to be tacky. The refractive index of the liquid before curing was 1.57, and the refractive index after curing (n Ｄ The visible light transmittance was 87% and the YI value was 5.5. The results are shown in Table 2.

[0107] Comparative Example 1 Photoradical Polymerization of Trimethylolpropane Triacrylate (TMPTA) 3 parts of Omnirad TPO as a photoradical polymerization initiator and 1 part of the fluorosurfactant Megafac F-477 (Megafac is a registered trademark of DIC Corporation) were added to 100 parts of trimethylolpropane triacrylate (TMPTA), and the mixture was dissolved by applying ultrasound. This photoradical polymerizable composition was formed into a film of 10 μm on a glass substrate using a bar coater, and after replacing the atmosphere inside the exposure machine with nitrogen, the film was exposed to light of 365 nm wavelength at an illuminance of 100 mW and an exposure dose of 30 J / cm. ２ The resin was irradiated and cured. After the exposure, the surface was checked for tackiness and found to be tacky. The refractive index of the liquid before curing was 1.47, and the refractive index after curing (n Ｄ The visible light transmittance was 100%, and the YI was 0.2. The results are shown in Tables 2 and 3.

[0108]

[0109] 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 polyfunctional (meth)acrylate, and there is an additivity between the refractive index of the copolymer composition and the mixing ratio of the compounds of the present invention. By mixing at a predetermined ratio, the refractive index (n Ｄ ) can be set to any value between 1.52 and 1.71. It is also clear that a copolymer using 2-vinylthiobenzoxazole, in which A in general formula (1) is an oxygen atom, can provide a copolymer with high transmittance and a low YI value.

[0110] [Example 10] Preparation of a photoradical copolymerization composition of 2-vinylthiobenzoxazole and polyfunctional (meth)acrylate 1 90 parts of 2-vinylthiobenzoxazole obtained in the same manner as in Synthesis Example 2 and 10 parts of trimethylolpropane triacrylate (TMPTA) were mixed and dissolved by applying ultrasound. The dissolution rate of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate was extremely fast, and they easily mixed together to form a homogeneous liquid phase. The refractive index (nＤ The viscosity was 5.1 mPa·s. The results are shown in Table 3 and FIG. 1.

[0111] [Example 11] Preparation 2 of a photoradical copolymerization composition of 2-vinylthiobenzoxazole and polyfunctional (meth)acrylate 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 ultrasound. The dissolution rate of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate was extremely fast, and they easily mixed together to form a homogeneous liquid phase. The refractive index (n Ｄ The viscosity was 14.4 mPa·s. The results are shown in Table 3 and FIG. 1.

[0112] Example 12: Preparation of a photoradical copolymerization composition of 2-vinylthiobenzoxazole and polyfunctional (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 ultrasound. The dissolution rate of 2-vinylthiobenzoxazole and trimethylolpropane triacrylate was extremely fast, and they easily mixed together to form a homogeneous liquid phase. The refractive index (n Ｄ The viscosity was 65.3 mPa·s. The results are shown in Table 3 and FIG. 1.

[0113] [Example 13] Preparation of a photoradical copolymerization composition of 2-vinylthiobenzothiazole and polyfunctional (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 ultrasound. The dissolution rate of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate was extremely fast, and they easily mixed together to form a homogeneous liquid phase. The refractive index (n Ｄ The viscosity was 9.3 mPa·s. The results are shown in Table 3 and FIG. 2.

[0114] Example 14: Preparation 2 of a photoradical copolymerization composition of 2-vinylthiobenzothiazole and polyfunctional (meth)acrylate. 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 ultrasound. The dissolution rate of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate was extremely fast, and they easily mixed together to form a homogeneous liquid phase. The refractive index (n Ｄ The viscosity was 24.8 mPa·s. The results are shown in Table 3 and FIG. 2.

[0115] [Example 15] Preparation 3 of a photoradical copolymerization composition of 2-vinylthiobenzothiazole and polyfunctional (meth)acrylate 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 ultrasound. The dissolution rate of 2-vinylthiobenzothiazole and trimethylolpropane triacrylate was extremely fast, and they easily mixed together to form a homogeneous liquid phase. The refractive index (n Ｄ The viscosity was 71.6 mPa·s. The results are shown in Table 3 and FIG. 2.

[0116]

[0117] 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 polyfunctional (meth)acrylate, in any desired composition to form a copolymer composition. ＤAs is clear from Figures 1 and 2, there is an additivity between the composition ratio and the refractive index, making it possible to adjust the refractive index of the composition. Furthermore, in terms of viscosity adjustment, the viscosity-reducing effect of the addition of 2-vinylthiobenzoxazole or 2-vinylthiobenzothiazole, a compound of the present invention, in a copolymer composition of 2-vinylthiobenzoxazole or 2-vinylthiobenzothiazole, a compound of the present invention, with trimethylolpropane triacrylate, a polyfunctional (meth)acrylate, is significant, and even the addition of a small amount can significantly reduce the viscosity of the copolymer composition. For example, in an example using 2-vinylthiobenzoxazole and trimethylolpropane triacrylate, Figure 1 shows that a copolymerizable composition with a viscosity of 30 mPa s or less at 25°C can be prepared by adding 2-vinylthiobenzoxazole in an amount of 32 wt % or more.

[0118] The compound of the present invention represented by general formula (1) is a radical polymerizable compound used as a transparent resin raw material suitable for optical applications, and is a radical polymerizable compound that not only has excellent curability but also low viscosity, and the polymer obtained by curing has excellent flexibility and a high refractive index.

Claims

1. A photoradical polymerizable composition comprising: (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. (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. The photoradical polymerizable composition according to claim 1, characterized in that the viscosity of the photoradical polymerizable composition at 25° C. is 30 mPa·s or less.

3. A photoradical polymerizable composition as described in claim 1, characterized in that (B) the radically polymerizable compound having a (meth)acrylic group is one or more radically polymerizable compounds selected from the group consisting of monofunctional (meth)acrylates, monofunctional (meth)acrylamides, polyfunctional (meth)acrylates and polyfunctional (meth)acrylamides.

4. The photoradical polymerizable composition described in claim 1, characterized in that (C) the 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, triazine-based photoradical polymerization initiators and thioxanthone-based photoradical polymerization initiators.

5. A photoradically polymerizable composition according to claim 1, characterized in that the content of (A) the vinyl sulfide compound having a heterocycle 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.

6. A polymerization method comprising irradiating the photoradically polymerizable composition according to any one of claims 1 to 5 with active energy rays.

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, the refractive index (n Ｄ ) is 1.50 or more.

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