Curable resin composition

Abstract

The purpose of the present invention is to provide a curable resin composition which has excellent coating and curing properties and has excellent light diffusion properties once cured. The present invention is a curable resin composition containing polymerisable monomers. The curable resin composition does not contain a polymer in which the number of repeating units is 4 or more, or the content ratio of a polymer in which the number of repeating units is 4 or more is 50 mass% or less of the curable resin composition. The haze of an uncured, 30 μm–thick coating film of the curable resin composition is 1.0% or less when measured in accordance with JIS K 7136, and the haze of a 30 μm–thick cured product of the curable resin composition is 5.0% to 99.0% when measured in accordance with JIS K 7136.

Description

Curable resin composition

[0001] The present invention relates to a curable resin composition.

[0002] Light-emitting diodes (LEDs) are widely used in display devices and the like due to their low power consumption and long life. In recent years, display devices that enable high-quality image display by mounting LED chips using tiny LEDs called micro-LEDs have attracted attention (see, for example, Patent Document 1). Devices using LEDs have the challenge of improving light extraction efficiency and uniformity. In particular, methods for converting monochromatic LED light require a layer that diffuses light (light diffusion layer) to uniformly guide the light emitted from the light source to the color conversion layer.

[0003] Japanese Patent Application Laid-Open No. 2019-212694

[0004] A light diffusion layer is usually formed by applying a curable resin composition using a coating device and then curing the applied composition. Therefore, the curable resin composition used in the light diffusion layer is required to have excellent coatability, curability, and light diffusion properties after curing. An object of the present invention is to provide a curable resin composition that has excellent coatability and curability, and also has excellent light diffusion properties after curing.

[0005] Disclosure 1 is a curable resin composition containing a polymerizable monomer, wherein the curable resin composition does not contain a polymer having four or more repeating units or the content of polymers having four or more repeating units in the curable resin composition is 50 mass% or less, a 30 μm-thick coating film of the curable resin composition before curing has a haze of 1.0% or less as measured in accordance with JIS K 7136, and a 30 μm-thick cured product of the curable resin composition has a haze of 5.0% or more and 99.0% or less as measured in accordance with JIS K 7136. Disclosure 2 is the curable resin composition of Disclosure 1, wherein the polymerizable monomer includes an aliphatic monomer not having an alicyclic skeleton and an aromatic monomer, and the maximum difference in solubility parameter between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer is 1.5 or more. Disclosure 3 is the curable resin composition of Disclosure 1 or 2, wherein the polymerizable monomer comprises an aliphatic monomer not having an alicyclic skeleton and an aromatic monomer, and wherein a maximum difference in the dispersion term δD of the Hansen solubility parameters between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer is 1.4 or more. Disclosure 4 is the curable resin composition of Disclosure 1, 2, or 3, wherein the polymerizable monomer comprises an aliphatic monomer not having an alicyclic skeleton and an aromatic monomer, and wherein a maximum difference in the polar term δP of the Hansen solubility parameters between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer is 1.3 or more. Disclosure 5 is the curable resin composition of Disclosure 1, 2, 3, or 4, wherein the polymerizable monomer comprises an aliphatic monomer not having an alicyclic skeleton and an aromatic monomer, and wherein a maximum difference in the hydrogen bond term δH of the Hansen solubility parameters between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer is 1.2 or more.

[0014] The present disclosure 6 is the curable resin composition of disclosure 1, 2, 3, 4, or 5, wherein the polymerizable monomer includes an aliphatic monomer not having an alicyclic skeleton and an aromatic monomer, and the maximum difference in refractive index between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer is 0.07 or more.

[0015] The present disclosure 7 is the curable resin composition of disclosure 2, 3, 4, 5, or 6, wherein the polymerizable monomer further includes an aliphatic monomer having an alicyclic skeleton. The present invention is described in detail below.

[0006] The present inventors have investigated the possibility of adjusting the haze before and after curing of a curable resin composition containing a polymerizable monomer, by making the composition contain no or almost no oligomer or polymer component, and have found that a curable resin composition having excellent coatability and curability and excellent light diffusion properties after curing can be obtained, thereby completing the present invention.

[0007] The curable resin composition of the present invention has a haze of 1.0% or less (hereinafter also referred to as "pre-cure haze") measured in accordance with JIS K 7136 for a 30 μm-thick coating film of the curable resin composition before curing. Having a pre-cure haze of 1.0% or less results in the curable resin composition of the present invention having excellent photocurability. The upper limit of the pre-cure haze is preferably 0.02%. The lower the pre-cure haze, the more preferable, with 0% being the most preferable. The pre-cure haze is measured by the following method. First, the curable resin composition is applied to a 0.7 mm-thick alkali-free glass substrate using a spin coater to form a 30 μm-thick coating film, thereby obtaining a test specimen. The obtained test specimen is irradiated with light having a wavelength of 400 to 700 nm from the surface of the coating film of the curable resin composition using a haze meter, and the pre-cure haze is measured in accordance with JIS K 7136. As the alkali-free glass substrate, for example, AN10 (manufactured by AGC) or the like can be used, and as the haze meter, for example, COH7700 (manufactured by Nippon Denshoku Industries Co., Ltd.) or the like can be used.

[0008] The curable resin composition of the present invention has a haze (hereinafter also referred to as "cured haze") of 5.0% or more and 99.0% or less for a 30 μm-thick cured product of the curable resin composition, measured in accordance with JIS K 7136. By adjusting the cured haze within this range, the curable resin composition of the present invention can be suitably used for various applications. The cured haze is measured by the following method. That is, first, the curable resin composition is applied to a 0.7 mm-thick alkali-free glass substrate using a spin coater to form a coating film of 30 μm in thickness. The obtained coating film is then irradiated with a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm. ２ The curable resin composition is cured by irradiating the cured product with ultraviolet light of 400 to 700 nm for 30 seconds, and then heated in an oven at 80°C for 30 minutes to obtain a test piece having a cured product with a thickness of 30 μm. The obtained test piece is irradiated with light of 400 to 700 nm wavelength from the side of the cured product of the curable resin composition using a haze meter, and the haze after curing is measured in accordance with JIS K 7136. The alkali-free glass substrate may be, for example, AN10 (manufactured by AGC), and the haze meter may be, for example, COH7700 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0009] The haze before curing and the haze after curing can be set within the above-mentioned ranges by adjusting the types and contents of the polymerizable monomer and other components contained in the curable resin composition of the present invention.

[0010] The curable resin composition of the present invention contains a polymerizable monomer. The polymerizable monomer refers to a monomer having a polymerizable group. Examples of the polymerizable group include a cationically polymerizable group and a radically polymerizable group. Among these, a cationically polymerizable group is preferred, and an epoxy group and an oxetanyl group are more preferred.

[0011] The polymerizable monomer preferably contains an aliphatic monomer having no alicyclic skeleton and an aromatic monomer. By containing the aliphatic monomer having no alicyclic skeleton and the aromatic monomer, the curable resin composition of the present invention can easily adjust the haze before curing, the haze after curing, and the viscosity described below. In particular, by forming a phase-separated structure when the aliphatic monomer having no alicyclic skeleton and the aromatic monomer are polymerized by light irradiation, it becomes easier to set the haze after curing within the above-mentioned range.

[0012] The maximum difference in solubility parameters between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer (hereinafter also referred to as the "maximum difference in SP values") is preferably 1.5 or more. When the maximum difference in SP values ​​is 1.5 or more, a phase-separated structure is more likely to be formed when the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer are polymerized by light irradiation, making it easier to achieve a haze within the above-mentioned range after curing. A more preferred lower limit of the maximum difference in SP values ​​is 1.9. There is no particular preferred upper limit of the maximum difference in SP values, but the practical upper limit is 10.0. Note that the solubility parameter (SP value) referred to herein is the Hansen solubility parameter, which can be derived by calculation from the structural formula using HSP software. The HSP software that can be used is Hansen Solubility Parameter in Practice (HSPiP). Furthermore, the maximum difference in SP values ​​means the larger of a and b, where a is the absolute difference between the SP value of the aliphatic monomer having the largest SP value among the aliphatic monomers not having an alicyclic skeleton and the SP value of the aromatic monomer having the smallest SP value, and b is the absolute difference between the SP value of the aliphatic monomer having the smallest SP value among the aliphatic monomers not having an alicyclic skeleton and the SP value of the aromatic monomer having the largest SP value.

[0013] The maximum difference in dispersion term δD of the Hansen solubility parameters between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer (hereinafter also referred to as "maximum difference in δD") is preferably 1.4 or more. When the maximum difference in δD is 1.4 or more, a phase separation structure is easily formed when the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer are polymerized by light irradiation, making it easier to keep the haze after curing within the above-mentioned range. A more preferred lower limit of the maximum difference in δD is 3.2. There is no particular preferred upper limit of the maximum difference in δD, but the practical upper limit is 5.0. The δD can be derived from the structural formula by calculation using the above-mentioned HSP software. Furthermore, the maximum difference in δD means the larger of c and d, where c is the absolute difference between the δD of the aliphatic monomer having the largest δD among the aliphatic monomers not having an alicyclic skeleton and the δD of the aromatic monomer having the smallest δD, and d is the absolute difference between the δD of the aliphatic monomer having the smallest δD among the aliphatic monomers not having an alicyclic skeleton and the δD of the aromatic monomer having the largest δD.

[0014] The maximum difference in polarity term δP of the Hansen solubility parameters between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer (hereinafter also referred to as "maximum difference in δP") is preferably 1.3 or more. When the maximum difference in δP is 1.3 or more, a phase separation structure is more likely to be formed when the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer are polymerized by light irradiation, making it easier to achieve the haze after curing within the above-mentioned range. A more preferred lower limit of the maximum difference in δP is 1.5. There is no particular preferred upper limit of the maximum difference in δP, but the practical upper limit is 5.0. The δP can be derived from the structural formula by calculation using the above-mentioned HSP software. Furthermore, the maximum difference in δP means the larger of e and f, where e is the absolute difference between the δP of the aliphatic monomer having the largest δP among the aliphatic monomers not having an alicyclic skeleton and the δP of the aromatic monomer having the smallest δP, and f is the absolute difference between the δP of the aliphatic monomer having the smallest δP among the aliphatic monomers not having an alicyclic skeleton and the δP of the aromatic monomer having the largest δP.

[0015] The maximum difference in the hydrogen bond term δH of the Hansen solubility parameters between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer (hereinafter also referred to as the "maximum difference in δH") is preferably 1.2 or more. When the maximum difference in δH is 1.2 or more, a phase separation structure is more likely to be formed when the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer are polymerized by light irradiation, making it easier to achieve a haze after curing within the above-mentioned range. A more preferred lower limit of the maximum difference in δH is 1.6. There is no particular preferred upper limit of the maximum difference in δH, but the practical upper limit is 5.0. The δH can be derived from the structural formula by calculation using the HSP software described above. Furthermore, the maximum difference in δH means the larger of g and h, where g is the absolute difference between the δH of the aliphatic monomer having the largest δH among the aliphatic monomers not having an alicyclic skeleton and the δH of the aromatic monomer having the smallest δH, and h is the absolute difference between the δH of the aliphatic monomer having the smallest δH among the aliphatic monomers not having an alicyclic skeleton and the δH of the aromatic monomer having the largest δH.

[0016] The maximum difference in refractive index between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer (hereinafter also referred to as "maximum difference in refractive index") is preferably 0.07 or more. When the maximum difference in refractive index is 0.07 or more, it becomes easier to set the haze after curing within the above-mentioned range. A more preferable lower limit of the maximum difference in refractive index is 0.14. There is no particular preferable upper limit of the maximum difference in refractive index, but the substantial upper limit is 0.30. Note that, in this specification, the refractive index refers to the refractive index at the sodium D line measured using an Abbe refractometer at 25°C. As the Abbe refractometer, for example, a Universal Abbe refractometer ER-7MW (manufactured by ERMA) or the like can be used. Furthermore, when the absolute difference between the refractive index of the aliphatic monomer having the largest refractive index among the aliphatic monomers not having an alicyclic skeleton and the refractive index of the aromatic monomer having the smallest refractive index is defined as i, and the absolute difference between the refractive index of the aliphatic monomer having the smallest refractive index among the aliphatic monomers not having an alicyclic skeleton and the refractive index of the aromatic monomer having the largest refractive index is defined as j, the maximum difference in refractive index means the larger value of i and j.

[0017] Examples of the aliphatic monomer not having an alicyclic skeleton include aliphatic epoxy compounds not having an alicyclic skeleton and aliphatic oxetane compounds not having an alicyclic skeleton. Examples of the aliphatic epoxy compounds not having an alicyclic skeleton include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and trimethylolpropane triglycidyl ether. Examples of the aliphatic oxetane compounds not having an alicyclic skeleton include 3-ethyl-3-((2-ethylhexyloxy)methyl)oxetane, 3-ethyl-3-(4-hydroxybutyloxymethyl)oxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(((3-ethyloxetan-3-yl)methoxy)methyl)oxetane, and 3-ethyl-3-((3-(triethoxysilyl)propoxy)methyl)oxetane.

[0018] The content of the aliphatic monomer not having an alicyclic skeleton in 100 parts by mass of the polymerizable monomer is preferably 10 parts by mass at the lower limit and 90 parts by mass at the upper limit. By having the content of the aliphatic monomer not having an alicyclic skeleton in this range, it becomes easier to set the haze after curing to the above-mentioned range. The content of the aliphatic monomer not having an alicyclic skeleton is more preferably 30 parts by mass at the lower limit and 70 parts by mass at the upper limit.

[0019] Examples of the aromatic monomer include aromatic epoxy compounds and aromatic oxetane compounds. Examples of the aromatic epoxy compounds include 4-tert-butylphenyl glycidyl ether, o-phenylphenol glycidyl ether, bisphenol A epoxy compounds, bisphenol F epoxy compounds, and bisphenol E epoxy compounds. Examples of the aromatic oxetane compounds include phenoxymethyl oxetane, 3-ethyl-3-(phenoxymethyl)oxetane, 1,4-bis(((3-ethyl-3-oxetanyl)methoxy)methyl)benzene, 4,4-bis((3-ethyl-3-oxetanyl)methoxymethyl)biphenyl, and bis((3-ethyl-3-oxetanylmethyl)isophthalate).

[0020] The aromatic monomer content in 100 parts by mass of the polymerizable monomer preferably has a lower limit of 10 parts by mass and an upper limit of 90 parts by mass. By ensuring that the aromatic monomer content is within this range, it becomes easier to achieve a post-curing haze within the aforementioned range. The aromatic monomer content is more preferably 30 parts by mass and 70 parts by mass.

[0021] It is preferable that the polymerizable monomer further contains an aliphatic monomer having an alicyclic skeleton. By containing the aliphatic monomer having an alicyclic skeleton, the resulting curable resin composition has better curability. Furthermore, by containing the aliphatic monomer having an alicyclic skeleton, phase separation of the polymerizable monomer in the curable resin composition before curing is less likely to occur, and the resulting curable resin composition has excellent storage stability. Note that a polymerizable monomer having an alicyclic skeleton and an aromatic ring is treated as the aromatic monomer.

[0022] Examples of the aliphatic monomer having an alicyclic skeleton include an aliphatic epoxy compound having an alicyclic skeleton, an aliphatic oxetane compound having an alicyclic skeleton, etc. Examples of the aliphatic epoxy compound having an alicyclic skeleton include an alicyclic epoxy-modified silicone compound, a dicyclopentadiene-type epoxy compound, 3,4-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate, 4,4'-bis(1,2-epoxycyclohexane), etc. Examples of the aliphatic oxetane compound having an alicyclic skeleton include 3-(cyclohexyloxy)methyl-3-ethyloxetane, 2-cyclohexyloxetan-3-one, etc.

[0023] The content of the aliphatic monomer having an alicyclic skeleton in 100 parts by mass of the polymerizable monomer is preferably 3 parts by mass at the lower limit and 40 parts by mass at the upper limit. When the content of the aliphatic monomer having an alicyclic skeleton is within this range, the resulting curable resin composition has better curability and light diffusion properties after curing. The content of the aliphatic monomer having an alicyclic skeleton is more preferably 5 parts by mass at the lower limit and 30 parts by mass at the upper limit.

[0024] The preferred lower limit of the content of the polymerizable monomer in the curable resin composition of the present invention is 60% by mass, and the preferred upper limit is 95% by mass. By having the content of the polymerizable monomer in this range, the resulting curable resin composition will have better coatability, curability, and light diffusion properties after curing. The more preferred lower limit of the content of the polymerizable monomer is 70% by mass, and the more preferred upper limit is 80% by mass.

[0025] The curable resin composition of the present invention preferably further contains a photopolymerization initiator. Examples of the photopolymerization initiator include a photocationic polymerization initiator and a photoradical polymerization initiator. In particular, it is preferable to use the photocationic polymerization initiator in combination with a polymerizable monomer having a cationically polymerizable group as the polymerizable monomer.

[0026] The photocationic polymerization initiator is not particularly limited as long as it generates a protonic acid or a Lewis acid upon irradiation with light, and may be either an ionic photoacid generating type or a nonionic photoacid generating type.

[0027] The anion moiety of the ionic photoacid generating cationic photopolymerization initiator may be, for example, BF ４ － , P.F. ６ － , SbF ６ － , (BX ４ ) － (wherein X represents a phenyl group substituted with at least two fluorine atoms or trifluoromethyl groups). Examples of the anion moiety include PF ｍ (C ｎ F ２ｎ＋１ ) ６－ｍ － (wherein, m is an integer of 0 or more and 5 or less, and n is an integer of 1 or more and 6 or less). Examples of the ionic photoacid-generating photocationic polymerization initiator include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, aromatic ammonium salts, and (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salts, which have the anion moiety.

[0028] Examples of the aromatic sulfonium salts include bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(diphenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(diphenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(diphenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio)phenylsulfonium tetrafluoroborate, diphenyl-4-(phenylthio)phenylsulfonium tetrakis(pentafluorophenyl)borate, triphenylsulfonium hexafluorophosphate, Examples of the sulfonium tetrakis(pentafluorophenyl)borate include triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluorophosphate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bishexafluoroantimonate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide bistetrafluoroborate, bis(4-(di(4-(2-hydroxyethoxy))phenylsulfonio)phenyl)sulfide tetrakis(pentafluorophenyl)borate, and tris(4-(4-acetylphenyl)thiophenyl)sulfonium tetrakis(pentafluorophenyl)borate.

[0029] Examples of the aromatic iodonium salts include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis(pentafluorophenyl)borate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium tetrakis(pentafluorophenyl)borate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluorophosphate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium hexafluoroantimonate, 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrafluoroborate, and 4-methylphenyl-4-(1-methylethyl)phenyliodonium tetrakis(pentafluorophenyl)borate.

[0030] Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis(pentafluorophenyl)borate.

[0031] Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl-2-cyanopyridinium tetrakis(pentafluorophenyl)borate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluorophosphate, 1-(naphthylmethyl)-2-cyanopyridinium hexafluoroantimonate, 1-(naphthylmethyl)-2-cyanopyridinium tetrafluoroborate, and 1-(naphthylmethyl)-2-cyanopyridinium tetrakis(pentafluorophenyl)borate.

[0032] Examples of the (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe salt include (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluorophosphate, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) hexafluoroantimonate, (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) tetrafluoroborate, and (2,4-cyclopentadien-1-yl)((1-methylethyl)benzene)-Fe(II) tetrakis(pentafluorophenyl)borate.

[0033] Examples of the nonionic photoacid generating cationic photopolymerization initiator include nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenolsulfonic acid esters, diazonaphthoquinone, and N-hydroxyimide sulfonates.

[0034] Among the above-mentioned cationic photopolymerization initiators, commercially available ones include, for example, cationic photopolymerization initiators manufactured by Midori Chemical Industry Co., Ltd., cationic photopolymerization initiators manufactured by Union Carbide Corporation, cationic photopolymerization initiators manufactured by ADEKA Corporation, cationic photopolymerization initiators manufactured by 3M Corporation, cationic photopolymerization initiators manufactured by BASF Corporation, cationic photopolymerization initiators manufactured by Rhodia Corporation, and cationic photopolymerization initiators manufactured by San-Apro Corporation. Examples of the cationic photopolymerization initiators manufactured by Midori Chemical Industry Co., Ltd. include DTS-200. Examples of the cationic photopolymerization initiators manufactured by Union Carbide Corporation include UVI6990 and UVI6974. Examples of the cationic photopolymerization initiators manufactured by ADEKA Corporation include SP-150 and SP-170. Examples of the cationic photopolymerization initiators manufactured by 3M Corporation include FC-508 and FC-512. Examples of the cationic photopolymerization initiator manufactured by BASF include IRGACURE 261 and IRGACURE 290. Examples of the cationic photopolymerization initiator manufactured by Rhodia include PI 2074. Examples of the cationic photopolymerization initiator manufactured by San-Apro include CPI-100P, CPI-200K, CPI-210S, and CPI-410S.

[0035] The preferred lower limit of the content of the photopolymerization initiator relative to 100 parts by mass of the polymerizable monomer is 0.01 parts by mass, and the preferred upper limit is 10 parts by mass. When the content of the photopolymerization initiator is 0.01 parts by mass or more, the resulting curable resin composition has better photocurability. When the content of the photopolymerization initiator is 10 parts by mass or less, the curing reaction of the resulting curable resin composition does not become too fast, resulting in better workability and a more uniform cured product. The more preferred lower limit of the content of the photopolymerization initiator is 0.05 parts by mass, and the more preferred upper limit is 5 parts by mass.

[0036] The curable resin composition of the present invention does not contain a polymer having four or more repeating units, or the content of the polymer having four or more repeating units in the curable resin composition is 50% by mass or less. Hereinafter, the polymer having four or more repeating units is also referred to as an "oligomer or polymer component." When the curable resin composition contains the oligomer or polymer component, a phase separation structure is easily formed after curing, and the resulting cured product is likely to have excellent light diffusion properties, but the viscosity becomes too high, resulting in poor coatability. When the curable resin composition of the present invention does not contain the oligomer or polymer component, or the content of the oligomer or polymer component is 50% by mass or less, the curable resin composition maintains excellent light diffusion properties after curing while also exhibiting excellent coatability. The content of the oligomer or polymer component is more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 1% by mass or less. Most preferably, the curable resin composition of the present invention does not contain the oligomer or polymer component.

[0037] The curable resin composition of the present invention preferably does not contain a filler, or the filler content in the curable resin composition is preferably 20% by mass or less. When the curable resin composition of the present invention does not contain the filler, or the filler content in the curable resin composition is 20% by mass or less, the resulting curable resin composition has better coatability, and it becomes easier to adjust the haze before curing to the above-mentioned range. The filler content is more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less. It is most preferable that the curable resin composition of the present invention does not contain the filler.

[0038] The curable resin composition of the present invention may contain, as needed, various known additives such as a leveling agent, a sensitizer, a heat curing agent, a silane coupling agent, a plasticizer, a curing retarder, an ultraviolet absorber, an antioxidant, a flame retardant, an antistatic agent, and an antifoaming agent, within the scope of not impairing the object of the present invention.

[0039] Examples of a method for producing the curable resin composition of the present invention include a method in which a polymerizable monomer, a photopolymerization initiator, and a leveling agent added as needed are uniformly mixed using a stirrer.

[0040] The curable resin composition of the present invention has a viscosity at 25°C of preferably 5.0 mPa·s as a lower limit and 100.0 mPa·s as an upper limit. When the viscosity at 25°C is within this range, the curable resin composition of the present invention has excellent coatability by an inkjet method or the like. The viscosity at 25°C is more preferably 10.0 mPa·s as a lower limit and 50.0 mPa·s as an upper limit. The viscosity can be measured, for example, using a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer and a No. 1 rotor at a rotation speed of 100 rpm.

[0041] The curable resin composition of the present invention can be cured by light irradiation. Examples of a method for curing the curable resin composition of the present invention by light irradiation include a method using a wavelength of 300 nm or more and 400 nm or less and a light irradiation rate of 300 mJ / cm. ２ More than 3000mJ / cm ２ Examples of the method include irradiating light with the following integrated light amount.

[0042] Examples of light sources for irradiating the curable resin composition of the present invention with light include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, excimer lasers, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, sodium lamps, halogen lamps, xenon lamps, LED lamps, fluorescent lamps, sunlight, electron beam irradiation devices, etc. These light sources may be used alone or in combination of two or more.

[0043] Examples of means for irradiating the curable resin composition of the present invention with light include simultaneous irradiation from various light sources, sequential irradiation with a time lag, and a combination of simultaneous irradiation and sequential irradiation, and any of these irradiation means may be used.

[0044] According to the present invention, it is possible to provide a curable resin composition that has excellent coatability and curability, and also has excellent light diffusion properties after curing.

[0045] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0046] (Examples 1 to 18, Comparative Examples 1 to 7) The curable resin compositions of Examples 1 to 18 and Comparative Examples 1 to 7 were prepared by stirring and mixing the materials using a stirrer according to the blending ratios shown in Tables 1 to 3. The stirrer used was an ARE-310 Awatori Rentaro (manufactured by Thinky Corporation). The "Actflow BE2" used in Comparative Example 7 is a polymer having four or more repeating units.

[0047] (Maximum Difference in SP Values, Maximum Difference in δD, Maximum Difference in δP, and Maximum Difference in δH) For each polymerizable monomer used in the Examples and Comparative Examples, the SP values, δD, δP, and δH derived using HSPiP, as well as the maximum differences in SP values, maximum differences in δD, maximum differences in δP, and maximum differences in δH calculated from these values, are shown in Tables 1 to 3.

[0048] (Maximum Difference in Refractive Index) The refractive index of each polymerizable monomer used in the Examples and Comparative Examples was measured at 25°C with an Abbe refractometer ("Universal Abbe Refractometer ER-7MW" manufactured by ERMA) at the sodium D line. The results are shown in Tables 1 to 3. The maximum differences in refractive index calculated from the obtained refractive index values ​​are also shown in Tables 1 to 3.

[0049] (Haze before curing) Each of the obtained curable resin compositions was applied to a 0.7 mm thick alkali-free glass substrate (manufactured by AGC, "AN10") using a spin coater to form a coating film of 30 μm, and a test specimen was obtained. The obtained test specimen was irradiated with light having a wavelength of 400 to 700 nm from the coating film side of the curable resin composition using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., "COH7700"), and the haze before curing was measured in accordance with JIS K 7136. The results are shown in Tables 1 to 3.

[0050] (Haze after curing) Each of the obtained curable resin compositions was applied to a 0.7 mm thick alkali-free glass substrate (manufactured by AGC, "AN10") using a spin coater to form a coating film with a thickness of 30 μm. The obtained coating film was irradiated with a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm. ２ The curable resin composition was cured by irradiating it with ultraviolet light of 400 to 700 nm for 30 seconds, and then heated in an oven at 80°C for 30 minutes to obtain a test piece having a cured product of 30 μm in thickness. The obtained test piece was irradiated with light of 400 to 700 nm wavelength from the side of the cured product of the curable resin composition using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., "COH7700"), and the haze after curing was measured in accordance with JIS K 7136. The results are shown in Tables 1 to 3.

[0051] <Evaluation> The curable resin compositions obtained in the examples and comparative examples were evaluated by the following methods. The results are shown in Tables 1 to 3.

[0052] (Viscosity) The viscosity of each of the obtained curable resin compositions was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., "VISCOMETER TV-22") and a No. 1 rotor at 25°C and a rotation speed of 100 rpm.

[0053] (Curability) Curability was evaluated by rating "A" when the haze measured in the above "(Haze before curing)" was 1.0 or less, and rating "B" when it exceeded 1.0.

[0054] (Light Diffusibility After Curing) The light diffusibility after curing was evaluated by rating the haze after curing as follows: if the haze measured in the above "(Haze after curing)" was 5.0% or more and 99.0% or less, it was rated as "A", and if it was less than 5.0% or more than 99.0%, it was rated as "B".

[0055] (Storage Stability) After preparation, each of the obtained curable resin compositions was stored for 24 hours in an environment of 25°C and 50% RH. The curable resin compositions after storage were visually observed, and the storage stability was evaluated by rating "A" when no phase separation was observed and "B" when phase separation was observed.

[0056]

[0057]

[0058]

[0059] As shown in Tables 1 to 3 above, the curable resin compositions obtained in Examples 1 to 18 were suitable for inkjet coating, whereas the curable resin composition obtained in Comparative Example 7 was not suitable for inkjet coating because of its extremely high viscosity at 25°C, and could not be coated by the inkjet method.

[0060] According to the present invention, it is possible to provide a curable resin composition that has excellent coatability and curability, and also has excellent light diffusion properties after curing.

Claims

1. A curable resin composition containing a polymerizable monomer, The polymerizable monomer includes an aliphatic monomer having no alicyclic skeleton, the aliphatic monomer not having an alicyclic skeleton includes at least one selected from the group consisting of an aliphatic epoxy compound not having an alicyclic skeleton and an aliphatic oxetane compound not having an alicyclic skeleton, the curable resin composition does not contain a polymer having a repeating unit number of 4 or more, or the content ratio of the polymer having a repeating unit number of 4 or more in the curable resin composition is 50 mass% or less; A coating film of the curable resin composition having a thickness of 30 μm before curing has a haze of 1.0% or less as measured in accordance with JIS K 7136, and a cured product of the curable resin composition having a thickness of 30 μm has a haze of 5.0% or more and 99.0% or less as measured in accordance with JIS K 7136. A curable resin composition comprising:

2. A curable resin composition containing a polymerizable monomer, the polymerizable monomer is a polymerizable monomer having a cationically polymerizable group, the curable resin composition does not contain a polymer having a repeating unit number of 4 or more, or the content ratio of the polymer having a repeating unit number of 4 or more in the curable resin composition is 50 mass% or less; A coating film of the curable resin composition having a thickness of 30 μm before curing has a haze of 1.0% or less as measured in accordance with JIS K 7136, and a cured product of the curable resin composition having a thickness of 30 μm has a haze of 5.0% or more and 99.0% or less as measured in accordance with JIS K 7136. A curable resin composition comprising:

3. 3. The curable resin composition according to claim 1, wherein the polymerizable monomer comprises an aliphatic monomer not having an alicyclic skeleton and an aromatic monomer, and a maximum difference in solubility parameter between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer is 1.5 or more.

4. The polymerizable monomer includes an aliphatic monomer having no alicyclic skeleton and an aromatic monomer, and a maximum difference in dispersion term δD of Hansen solubility parameters between the aliphatic monomer having no alicyclic skeleton and the aromatic monomer is 1.4 or more. The curable resin composition according to claim 1 or 2.

5. The polymerizable monomer includes an aliphatic monomer having no alicyclic skeleton and an aromatic monomer, and a maximum difference in polarity term δP of the Hansen solubility parameter between the aliphatic monomer having no alicyclic skeleton and the aromatic monomer is 1.3 or more. The curable resin composition according to claim 1 or 2.

6. The polymerizable monomer includes an aliphatic monomer having no alicyclic skeleton and an aromatic monomer, and a maximum difference in hydrogen bond term δH of Hansen solubility parameters between the aliphatic monomer having no alicyclic skeleton and the aromatic monomer is 1.2 or more. The curable resin composition according to claim 1 or 2.

7. 3. The curable resin composition according to claim 1, wherein the polymerizable monomer comprises an aliphatic monomer not having an alicyclic skeleton and an aromatic monomer, and a maximum difference in refractive index between the aliphatic monomer not having an alicyclic skeleton and the aromatic monomer is 0.07 or more.

8. The curable resin composition according to claim 3 , wherein the polymerizable monomer further comprises an aliphatic monomer having an alicyclic skeleton.