Photopolymerizable composition, optical member formed thereby, and display device

Abstract

The present invention relates to a photopolymerizable composition which can form an optical member exhibiting high flexibility and improved optical properties including high refractive index, excellent light transmittance and low haze, and having viscosity properties suitable for an inkjet process, an optical member formed therefrom, and a display device.

Description

Technical Field

[0001] The present invention relates to a photopolymerizable composition, optical components and display devices formed therefrom, which simultaneously improve optical properties (including excellent light transmittance, low haze and high refractive index) and mechanical and physical properties (including high flexibility and excellent bending reliability). Background Technology

[0002] For a transparent optical film with a structured prism, the rate of increase in brightness varies depending on the refractive index of the resin constituting the prism structure. Generally, the rate of increase in brightness increases with the increase in the refractive index of the resin constituting the prism. Therefore, research and development regarding such transparent optical films are moving towards increasing the refractive index of the resin constituting the prism.

[0003] For the high-refractive-index resins used to form the prisms, to ensure a high refractive index, they are typically formed as metal oxides dispersed in organic compounds. While the use of metal oxides results in a higher refractive index, it also leads to problems with haze and increased reflectivity. High reflectivity reduces the outdoor visibility of the display.

[0004] For the resins formed in the form of metal oxide dispersions, the product shelf life depends on the dispersion stability, making large-scale production difficult and leading to increased costs. Furthermore, compositions containing the aforementioned metal oxides exhibit problems such as decreased inkjet processability due to increased viscosity, thus presenting numerous technical limitations.

[0005] Furthermore, when conventional photopolymerizable compositions are used as monomer compositions to form the resin and optical film, surface curing often fails to occur fully during the photocuring process due to the influence of oxygen in the air. As a result, the resin and optical film exhibit problems such as increased haze and decreased light transmittance or visibility, including reduced ultraviolet transmittance. In addition, insufficient surface curing leads to a decrease in the mechanical properties of the film, significantly reducing the high flexibility and bending reliability required for foldable devices. Therefore, considering the above problems, a curing process in an inert gas environment such as nitrogen is considered, but this may result in a significant increase in the manufacturing cost.

[0006] With recent advancements in display technology, deformable display devices are being developed and mass-produced, including those that can be folded, rolled into a roll, or stretched like a rubber band. These displays can deform into various shapes, therefore the materials used must also possess deformable mechanical properties.

[0007] However, due to the aforementioned problems, it has not yet been developed to the point where it exhibits viscosity characteristics suitable for inkjet processes and meets the requirements of excellent optical properties and high flexibility. Therefore, it is still necessary to develop technologies that can form optical films that exhibit excellent optical and mechanical properties. Summary of the Invention

[0008] Technical issues

[0009] Based on this, the present invention provides a photopolymerizable composition that exhibits viscosity characteristics suitable for inkjet processes and suppresses haze increase during curing, thereby enabling the formation of optical components that simultaneously improve optical properties (including excellent light transmittance, low haze, and high refractive index) and mechanical and physical properties (including high elongation and excellent bending reliability).

[0010] The present invention also provides an optical component formed from the photopolymerizable composition, having improved optical properties (including excellent light transmittance, low haze and high refractive index) and mechanical properties (including high flexibility and excellent bending reliability).

[0011] In addition, the present invention provides a display device that includes the aforementioned optical components.

[0012] Technical solution

[0013] This invention provides a photopolymerizable composition comprising:

[0014] a) One or more high refractive index monomers with a liquid refractive index of 1.51 or higher before curing;

[0015] b) One or more highly flexible monomers; and

[0016] c) Photopolymerization initiator.

[0017] The present invention also provides an optical component comprising: a substrate; and a cured film comprising a cured product of the photopolymerizable composition.

[0018] In addition, the present invention provides a display device that includes the aforementioned optical components.

[0019] Invention Effects

[0020] The photopolymerizable composition according to this specification exhibits viscosity characteristics suitable for inkjet printing processes, and can simultaneously form a cured film with a high refractive index and optical components comprising the cured film. Furthermore, due to the specific highly flexible monomers contained in the photopolymerizable composition, the mechanical properties of the cured product, such as flexibility and bending reliability, can be improved. Additionally, the amine enhancer contained in the photopolymerizable composition significantly reduces the problem of reduced surface curing caused by oxygen, resulting in optical components exhibiting low haze, excellent ultraviolet transmittance, and high visibility.

[0021] Furthermore, the curing process of the photopolymerizable composition does not require a nitrogen atmosphere, which can greatly improve the overall economic efficiency of the process.

[0022] Therefore, the optical components formed from the photopolymerizable composition have low manufacturing costs and exhibit low haze, high refractive index, excellent light transmittance and visibility, as well as excellent flexibility and bending properties, which greatly contributes to improving the characteristics of foldable or flexible display devices. Detailed Implementation

[0023] The invention will be described in more detail below. The terms or words used in this specification and claims should not be construed as limited to their general or dictionary meanings, but should be interpreted as conforming to the technical concept of the invention, provided that the inventors can appropriately define the concepts of the terms to best describe the invention.

[0024] Furthermore, the term "comprising" as used in the specification of this invention indicates the presence of a certain characteristic, field, integer, step, operation, element, and / or component, and does not exclude the presence of other characteristics, fields, integers, steps, operations, elements, and / or components.

[0025] In the instructions, "(meth)acrylate" can refer to either "acrylate" or "methacrylate".

[0026] The embodiments will be described in detail below to enable those skilled in the art to implement the invention. The embodiments can be implemented in various different ways and are not limited to the embodiments described below.

[0027] According to a specific embodiment of the present invention, a photopolymerizable composition can be provided, comprising: a) one or more high refractive index monomers with a liquid refractive index of 1.51 or higher before curing; b) one or more highly flexible monomers; and c) a photopolymerization initiator.

[0028] In one specific embodiment of the photopolymerizable composition, high refractive properties can be achieved using only high-refractive-index monomers without the presence of metal oxides, and cracking of the cured film can be prevented by including highly flexible monomers with excellent elongation. Therefore, when an optical component having a cured film formed from the photopolymerizable composition is used in a foldable or flexible display device, the performance of the display element can be improved. Furthermore, even if the photopolymerizable composition contains only high-refractive-index and highly flexible monomers, it satisfies an appropriate viscosity range suitable for inkjet applications, enabling the cured product to achieve excellent optical and mechanical properties.

[0029] Because the photopolymerizable composition does not use metal oxides, it exhibits excellent surface curing properties during the photocuring process, thereby improving the haze characteristics, light transmittance, and visibility of the optical film, and avoiding an increase in the unit cost of production. In particular, due to the use of the highly flexible monomer, cracking is prevented as described above, thus ensuring the excellent high flexibility and bending reliability required for foldable or flexible devices. Furthermore, the curing process of the photopolymerizable composition does not require a nitrogen atmosphere, thereby significantly improving the overall economic efficiency of the process.

[0030] Furthermore, the photopolymerizable composition further comprises one or more components such as amine enhancers, photosensitizers, and surfactants, thereby improving the surface curability of the film used to provide the cured film. For example, the amine enhancer included in the photopolymerizable composition can significantly reduce the problem of decreased surface curing caused by the influence of oxygen. This is because, during the curing process, the amine groups included in the amine enhancer capture oxygen free radicals in the air, thereby further improving the reactivity of the polymerization initiator. In addition, the use of the photosensitizer can promote the polymerization reaction during photopolymerization. Furthermore, the use of the surfactant can impart effects such as improved film thickness uniformity or surface smoothness.

[0031] Therefore, when a photopolymerizable composition (containing not only the aforementioned high-refractive-index monomer, high-flexibility monomer, and photopolymerization initiator, but also additional components) is photocured to form a cured film and optical components, a high degree of surface curing is achieved even in an air environment. This allows the cured film to exhibit low haze, excellent ultraviolet transmittance, and high visibility. In particular, the photopolymerizable composition exhibits high flexibility and significantly improved bending characteristics, and displays a viscosity suitable for inkjet printing, thereby improving processability such as coating and film formation. Furthermore, the curing process of the photopolymerizable composition does not require a nitrogen atmosphere, thus greatly improving the overall economic efficiency of the process.

[0032] Therefore, when the photopolymerizable composition is used, optical components with low unit cost and exhibiting low haze, high refractive index, high flexibility, excellent light transmittance and visibility can be formed, thereby making a significant contribution to improving the characteristics of various types of display devices.

[0033] Specifically, the components used in the photopolymerizable composition are described below.

[0034] In one specific embodiment, the photopolymerizable composition, as a base monomer for forming a cured film matrix, contains one or more high refractive index monomers with a liquid refractive index of 1.51 or higher before curing.

[0035] The high-refractive-index monomer can form a base resin, which, through a photocuring process described later, undergoes photocurable functional group crosslinking polymerization mediated by a photopolymerization initiator to form a cured film. In particular, since the high-refractive-index monomer satisfies a specific liquid crystal refractive index range, it can improve the refractive index of the cured film based on ultraviolet irradiation. More specifically, the liquid refractive index of the high-refractive-index monomer before curing can be between 1.51 and 1.60. When the liquid refractive index of the high-refractive-index monomer is below 1.51, there is a problem that the refractive index of the cured film decreases to below 1.58.

[0036] The high refractive index monomer can be an aromatic or alicyclic photocurable compound containing one or more aromatic rings or one or more heteroatoms.

[0037] Specifically, the high refractive index monomer may be an aromatic or alicyclic photocurable compound containing one or more aromatic rings or one or more heteroatoms and having photocurable functional groups with 10 to 40 carbon atoms.

[0038] More specifically, the high refractive index monomer may be an aromatic photocurable compound comprising the structure of Chemical Formula 1 below:

[0039] [Chemical Formula 1]

[0040] B-Z1-Z2-R

[0041] In the above chemical formula 1, B comprises any one or more of the following structures: an aryl group having 6 to 30 carbon atoms, a 5- to 7-membered aliphatic heterocyclic structure with one or more sulfur atoms (S) substituted, or a 5- to 7-membered aromatic heterocyclic structure with one or more sulfur atoms (S) substituted.

[0042] Z1 is a direct bond or an alkyl group having 1 to 10 carbon atoms.

[0043] Z2 is a direct bond or an alkyl group containing one or more oxygen (O) or sulfur (S) atoms with a carbon number of 1 to 10, and R is a photocurable functional group.

[0044] The high refractive index monomer may contain a structure of Formula 1, wherein B is an aryl group having 6 to 30 carbon atoms, Z1 is a direct bond, and Z2 is an alkyl group having 1 to 10 carbon atoms containing one or more oxygen (O) atoms.

[0045] The high refractive index monomer may contain a structure of chemical formula 1, wherein B is an aryl group having 6 to 30 carbon atoms, Z1 is a direct bond, and Z2 contains one or more oxygen (O) and an aromatic ring structure.

[0046] The high refractive index monomer may contain a structure of Formula 1, wherein B contains a 5- to 7-membered aromatic heterocyclic structure in which one or more sulfur (S) is substituted, Z1 is a direct bond, and Z2 is an alkyl group containing one or more sulfur (S) and having 1 to 10 carbon atoms.

[0047] The high-refractive-index monomer can be a liquid, but in the case of anthracene or sulfur-containing structures represented by the above chemical formula, it can exist in powder form instead of a liquid.

[0048] More specifically, the high refractive index monomers described above may comprise one or more selected from the group consisting of benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, biphenyl ethyl (meth)acrylate, and chemical formulas 2 to 8.

[0049] [Chemical Formula 2]

[0050]

[0051] [Chemical Formula 3]

[0052]

[0053] [Chemical Formula 4]

[0054]

[0055] [Chemical Formula 5]

[0056]

[0057] [Chemical Formula 6]

[0058]

[0059] [Chemical Formula 7]

[0060]

[0061] [Chemical Formula 8]

[0062]

[0063] In the above chemical formulas 2 to 8, R is independently H or CH3.

[0064] In particular, when the high refractive index monomer is an anthracene- or sulfur-containing structure, a refractive index of 1.61 or higher can be ensured.

[0065] On the other hand, according to this specification, the high-flexibility monomer is cured together with the high-refractive-index monomer, thereby significantly improving the flexibility and bending properties of the cured film and preventing cracking.

[0066] Specifically, the highly flexible monomer may contain one or more compounds with photocurable functional groups, which can increase the elongation of the final cured film by at least 5%.

[0067] The elongation can be determined as follows: after peeling a 20 μm thick film from plain glass to prepare a dog bone-shaped specimen (28 mm x 4 mm), the elongation is measured using a tensile stress-strain curve obtained by Instron's UTM.

[0068] The highly flexible monomer may contain a structure of the following chemical formula 9.

[0069] [Chemical Formula 9]

[0070] (A)mB-(A')n

[0071] In the above chemical formula 9, A and A', as photocurable functional groups, can be the same or different.

[0072] B, as an aliphatic structure with 6 to 50 carbon atoms, including or not including one or more oxygen atoms, must contain at least a straight-chain alkyl structure with 6 or more carbon atoms.

[0073] m and n are integers that are either 0 or 1.

[0074] The highly flexible monomer can be a structure of chemical formula 9 containing 4 to 20 oxygen atoms.

[0075] More specifically, the highly flexible monomer may be one or more selected from the group consisting of aliphatic mono(meth)acrylates having 6 to 30 carbon atoms and aliphatic di(meth)acrylates having 6 to 30 carbon atoms. The viscosity of the highly flexible monomer may be 1 to 30 cP.

[0076] More specifically, the highly flexible monomer may comprise one or more selected from the group consisting of isodecyl methacrylate, lauryl methacrylate, stearyl methacrylate, ethoxyethyl methacrylate, ethoxyethyl methacrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate and the following chemical formula 10.

[0077] [Chemical Formula 10]

[0078]

[0079] In the above chemical formula 10, a+b = 0 to 10, where a and b are integers.

[0080] In the above chemical formula 10, a and b can each be an integer from 1 to 5.

[0081] Based on a total weight of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the high-flexibility monomer may contain at least 10 parts by weight. Specifically, the photopolymerizable composition must contain at least 10 parts by weight of the high-flexibility monomer to improve the flexibility of the cured film.

[0082] More specifically, based on a total of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the high-flexibility monomer may contain 10 to 90 parts by weight. Additionally, based on a total of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the high-flexibility monomer may contain 10 to 40 parts by weight.

[0083] If the content of the highly flexible monomer is less than 10 parts by weight, the elongation after coating formation will be less than 5%, failing to improve flexibility. Furthermore, if the content of the highly flexible monomer is too high, exceeding 90 parts by weight, the refractive index will decrease, making it impossible to achieve a high refractive index of 1.58 or higher.

[0084] The photopolymerizable composition of one specific embodiment described above contains a photopolymerization initiator. This photopolymerization initiator can initiate and promote the photocuring reaction of the two specific monomers described above.

[0085] As such a photopolymerization initiator, any initiator known to initiate and promote the photocuring reaction of photocurable functional groups such as (meth)acrylate groups can be used.

[0086] Examples of the photopolymerization initiator include one or more compounds selected from the group consisting of triazine, benzoin, benzophenone, imidazole, xanthonesone, oxime ester, and acetophenone compounds. More specific examples of the photopolymerization initiator include compounds selected from 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine, 2-p-methoxystyryl-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-6-triazine, 2,4-trichloromethyl-4-methylnaphthyl-6-triazine, 2-(o-chlorophenyl)-4,5-diphenylimidazolium dimer, 2-(o-chlorophenyl)-4,5-diphenylimidazolium dimer, etc. 5-Di(m-methoxyphenyl)imidazolium dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazolium dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazolium dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazolium dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazolium dimer, 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazolium dimer, 2-(p-methylthiosulfate) 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-(O-acetyl oxime), benzophenone, p-(diethylamino)benzophenone, 2,2-dichloro-4-phenoxyacetophenone, 2,2-diethoxyacetophenone, 2-dodecylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,2-bis-2-chlorophenyl- 4,5,4,5-Tetraphenyl-2-1,2-diimidazole, (E)-2-(acetoxyimino)-1-(9,9-diethyl-9H-fluoren-2-yl)butanone, (E)-1-(9,9-dibutyl-7-nitro-9H-fluoren-2-yl)acetone-O-acetyl oxime, (Z)-2-(acetoxyimino)-1-(9,9-diethyl-9H-fluoren-2-yl)acetone, Irgacure Compounds in the group consisting of 369, Irgacure 651, Irgacure 907, Darocur TPO, Irgacure 819, OXE-01, OXE-02, OXE-03, OXE-04, Idico's N-1919, NCI-831 and NCI-930, in addition to which photopolymerization initiators known in the art may be widely used without any other limitations.

[0087] Based on 100 parts by weight of the total amount of the high-refractive-index monomer and the high-flexibility monomer, the photopolymerizable composition may contain 0.5 to 30 parts by weight of a photopolymerization initiator. As another example, based on 100 parts by weight of the total amount of the high-refractive-index monomer and the high-flexibility monomer, the photopolymerization initiator may contain 0.6 to 28% by weight and 1 to 25% by weight. If the content of the photopolymerization initiator becomes too low, photocuring may not be successful. On the other hand, if the content of the photopolymerization initiator becomes too high, the cumulative transmittance of the cured film, etc., may decrease, for example, to below 90%.

[0088] On the other hand, a composition of one specific embodiment, without containing metal oxides, can also achieve an absolute viscosity suitable for inkjet printing by using the aforementioned high-refractive-index monomer and high-flexibility monomer. Specifically, the absolute viscosity (measured at 25°C) of the photopolymerizable composition can be from 5 cP to 40 cP. Therefore, the composition of one specific embodiment containing the aforementioned high-refractive-index monomer and high-flexibility monomer exhibits excellent inkjet processability, as well as excellent heat resistance and mechanical properties, and can form a cured film with good coating characteristics. Furthermore, through the interaction between the olefin monomer and the metal oxide particles described later, the cured film and optical components formed using the composition of one specific embodiment can have a high refractive index of 1.58 or higher.

[0089] Incidentally, the absolute viscosity described in this specification refers to the absolute viscosity value measured at 25°C. This absolute viscosity can be measured using a viscometer well-known in the art, such as a Brinell viscometer.

[0090] On the other hand, the photopolymerizable composition of one specific embodiment may further comprise one or more selected from the group consisting of d) amine enhancers having amine and photocurable functional groups, e) photosensitizers and f) surfactants. The further inclusion of any one or more of the above-described components d) to f) as additives may help the photopolymerizable composition achieve its physical properties more effectively.

[0091] First, the photopolymerizable composition of one specific embodiment may contain an amine synergist having amine groups and photocurable functional groups. With this amine synergist, during the photocuring of the composition of one specific embodiment to form a cured film and optical components, the amine groups contained therein capture oxygen free radicals in the air, thereby promoting the reaction of the initiator. Furthermore, the photocurable functional groups in the amine synergist can form crosslinking bonds with the monomer. Under the action of this amine synergist, the cured film and optical components formed from the composition of one specific embodiment can exhibit high surface curing degree, thereby exhibiting excellent optical properties such as low haze and improved light transmittance.

[0092] The amine enhancer may comprise one of compounds selected from the group consisting of compounds having at least three amine groups and photopolymerizable acrylate groups in their molecules.

[0093] Specifically, as the amine reinforcing agent, any compound that has a functional group, together with the amine group in the molecule, capable of forming a crosslinking bond with a photocurable functional group such as the photocurable functional group of the aforementioned monomer can be used. In a more specific example, the functional group is a photocurable functional group of the same type as the monomer, which may be a (meth)acrylate group. Furthermore, in order to more effectively capture the oxygen free radicals, etc., to further improve the surface curing degree of the cured film, etc., the amine reinforcing agent more preferably contains a tertiary amine structure or higher in the molecule.

[0094] Specific examples of such amine enhancers include compounds selected from those of chemical formula 11, namely ethyl dimethylaminobenzoate, butoxyethyl dimethylaminobenzoate, bis(diethylamino)benzophenone, bis(2-hydroethyl)-toluidine, ethylhexyl-(dimethylamino)benzoate, 2-(dimethylamino)ethyl(meth)acrylate, diethylaminoethyl(meth)acrylate, 2-(diisopropylamino)ethyl(meth)acrylate, and 4-(dimethylamino)ethyl(meth)acrylate. It may use one or more of the group consisting of 2-(acryloyloxy)ethyl4-(dimethylamino)benzoate, 2-ethylhexyl4-(dimethylamino)benzoate, 4,4-(ethyl2-(dibutylamino)methylacrylate) and 4,4-(oxybis(ethane-2,1-diyl))bis(oxy)bis(dimethylaniline)), in addition to which various compounds having amine and photocurable functional groups may also be used.

[0095] [Chemical Formula 11]

[0096]

[0097] In the above chemical formula 11, R1 and R2 each independently represent an alkyl group having 1 to 5 carbon atoms, and R3 represents an alkyl group having 1 to 20 carbon atoms, an ether group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an amino group, or a (meth)acrylate group.

[0098] Alternatively, commercially available photocurable amine compounds can be used as the amine enhancer. Examples of such commercial compounds include P115 (provided by SK Cytec), MIRAMER AS2010 (provided by Miwon Commercial Co., Ltd.), or MIRAMER AS5142 (provided by Miwon Commercial Co., Ltd.).

[0099] Additionally, based on 100 parts by weight of the total amount of the high-refractive-index monomer and the high-flexibility monomer, the photopolymerizable composition may also contain 0.1 to 10 parts by weight of an amine reinforcing agent. As another example, based on 100 parts by weight of the total amount of the high-refractive-index monomer and the high-flexibility monomer, d) the amine reinforcing agent may contain 0.5 to 9 parts by weight. If the content of the amine reinforcing agent becomes too low, the surface curing degree decreases, and the haze of the cured film and optical components may increase. On the other hand, if the content of the amine reinforcing agent becomes too high, the viscosity of the photopolymerizable composition becomes too high, which may lead to decreased processability or a decrease in the refractive index of the cured film, etc.

[0100] The photosensitizer e) is included in the photopolymerizable composition, which further increases the curability of the high refractive index monomer and the high flexibility monomer, thereby giving the effect of improving the haze properties and increasing sensitivity.

[0101] The photosensitizer may be selected from one or more of the group consisting of isopropyl thioxanthone, pyrene, perylene, triphenylene, anthracene, 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 3,7-dimethoxyanthracene, and 9,10-dipropyloxyanthracene.

[0102] Based on 100 parts by weight of the total amount of the high-refractive-index monomer and the high-flexibility monomer, the photopolymerizable composition may further contain 0.1 to 10 parts by weight of a photosensitizer. As another example, based on 100 parts by weight of the total amount of the high-refractive-index monomer and the high-flexibility monomer, the photosensitizer (e) may contain 0.5 to 9 parts by weight. If the content of the photosensitizer becomes too low, it will not help improve the surface curing degree. On the other hand, if the content of the photosensitizer becomes too high, the viscosity of the photopolymerizable composition will become too high, resulting in decreased processability or decreased transmittance of the cured film, etc.

[0103] The surfactant mentioned in f) can impart effects such as improving film thickness uniformity or surface smoothness.

[0104] The surfactant may include one or more species selected from the group consisting of silicone-based and fluorinated surfactants.

[0105] Based on a total of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the surfactant (f) may contain 0.1 to 5 parts by weight. If the surfactant content becomes too low, problems may arise regarding film thickness uniformity or surface smoothness. On the other hand, if the surfactant content becomes too high, problems may arise regarding the formation of bubbles within the film or a decrease in inkjet characteristics.

[0106] On the other hand, in a specific embodiment of the photopolymerizable composition, in addition to the components described above, a dispersant may also be included as needed. The inclusion of such a dispersant in the photopolymerizable composition can improve the dispersion stability of the other components.

[0107] There are no particular restrictions on the type of dispersant; any known dispersant that can improve dispersibility can be used. Examples of such dispersants include one or more selected from the group consisting of acrylic dispersants, epoxy dispersants, and silicone dispersants.

[0108] Based on a total of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the dispersant may contain 0.1 to 30 parts by weight or 0.5 to 20 parts by weight. Depending on the content of the dispersant, the components are more uniformly dispersed, thereby more effectively achieving the desired refractive index range of the cured film. However, if the content of the dispersant becomes too high, the viscosity of the photopolymerizable composition increases, which may reduce the inkjet processability.

[0109] Furthermore, the composition of one specific embodiment described above can be formulated as a solvent-free composition that does not contain other solvents or liquid media. This further improves the processability of using the composition of that specific embodiment.

[0110] For a specific embodiment of the photopolymerizable composition comprising the above-described components, the absolute viscosity (measured at 25°C) can be from 5 cP to 40 cP or from 5 cP to 30 cP, as described above. This absolute viscosity can be measured using a known viscometer, such as a Brinell viscometer. When the photopolymerizable composition of a specific embodiment meets such a viscosity range, a cured film with excellent heat resistance and mechanical properties can be formed, exhibiting not only excellent inkjet processability but also good coating properties based on inkjet processes.

[0111] If the viscosity of the final composition becomes too low, the dispensing characteristics may decrease due to nozzle drying and clogging. Conversely, if the viscosity of the composition is too high, there may be issues with reduced dispensing volume or failure to form patterns and surfaces.

[0112] On the other hand, according to another specific embodiment of the present invention, a cured film comprising a cured product of the above-described photopolymerizable composition and an optical component comprising the cured film are provided. This optical component may comprise a substrate; and the cured film formed on the substrate. Furthermore, the cured film is formed by photocuring a photopolymerizable composition, as described in one specific embodiment, onto a substrate using an inkjet process. Therefore, it may primarily comprise a cured product containing a polymer having units crosslinked with photocurable functional groups of the olefin monomer and amine reinforcing agent, a dispersant dispersed on the polymer, and a metal oxide.

[0113] More specifically, the cured product comprises an olefin resin formed by curing and crosslinking a high-refractive-index monomer and a highly flexible monomer, wherein the olefin resin may optionally be further crosslinked with the photocurable functional groups of the amine reinforcing agent. Furthermore, the olefin resin, together with one or more selected from the group consisting of the aforementioned photosensitizers and surfactants, can improve photopolymerizability and film properties. In this case, the olefin resin is a polymer formed by crosslinking and polymerizing one or more high-refractive-index monomers having photocurable functional groups and one or more highly flexible monomers; its form is not limited and, depending on the type of monomer and the polymerization mechanism, can be various forms such as homopolymers, block copolymers, random copolymers, or graft copolymers.

[0114] On the other hand, according to another specific embodiment of the present invention, an optical component may be provided, comprising: a substrate; and a cured film comprising a cured product of the above-described highly flexible photopolymerizable composition for inkjet printing.

[0115] Since the cured film containing the cured material is formed using a photopolymerizable composition having a viscosity suitable for inkjet printing, as described in a specific embodiment, it exhibits excellent heat resistance, mechanical properties, and good coating characteristics. Furthermore, the cured film can have a haze of 3% or less, a refractive index of 1.58 or more, and an elongation of 5% or more.

[0116] Specifically, for the cured film, with a wavelength of 565 nm as a reference, the refractive index after photopolymerization can be 1.58 or higher. More specifically, the cured film can have a high refractive index, which can be 1.6 or higher, or 1.6 to 2.0, or 1.6 to 1.65. In this case, the refractive index can be a value measured using an ellipsometer at a wavelength of 555 to 575 nm (average).

[0117] In addition, the amine enhancer exhibits high surface curing degree, for example, it can show light transmittance and visibility such as low haze and excellent ultraviolet transmittance, with haze of less than 3%, less than 1%, or 0 to 1%, or 0.01 to 0.8%, or 0.1 to 0.3%.

[0118] In addition, for the cured film, after peeling a 20 μm thick film from the plain glass to prepare a dog bone-shaped specimen (28 mm x 4 mm in size), the elongation is determined by using the tensile stress-strain curve measured by Instron's UTM. The elongation can be 5% or more, or 5 to 10%, or 10% or more.

[0119] In the aforementioned optical components, a well-known substrate such as plain glass can be used as the substrate.

[0120] Furthermore, the optical component can be manufactured by applying the photopolymerizable composition of one specific embodiment described above onto the substrate using a mayer bar, a coating applicator, or an inkjet printer, and then photocuring it, for example, by exposure to air using an LED lamp or a metal halide lamp. In this case, the photopolymerizable composition can be photocured after being coated into a single film to form an optical component in the form of a general optical film. Alternatively, it can be photocured after being coated with an inkjet printer to form a specific pattern shape. In this case, the optical component can be formed as a patterned film on the substrate, for example, a patterned film with a patterned polyhedral structure such as a prism.

[0121] Optical components such as optical films or patterned films mentioned above can have a general thickness, depending on their type or the structure of the display element to which they are applied, for example, a thickness that can be adjusted in the range of 0.01 μm to 1000 μm.

[0122] Furthermore, for the aforementioned optical components, the sensitivity value can be below 3 J, and the transmittance can be above 90%. This sensitivity can be measured by comparing the absorbance measurements before and after exposure using an FT-IR spectrophotometer. More specifically, this is achieved by focusing on absorbance values ​​at 1650–1750 cm⁻¹. -1 C=O peak value and 780-880 cm -1 The conversion efficiency is calculated by integrating the peak value of C=C. Sensitivity refers to the exposure level at which saturation occurs with a conversion efficiency of 80% or higher. Furthermore, the transmittance refers to the average transmittance of optical components such as optical films measured using a UV-VIS spectrophotometer at wavelengths of 380–780 nm.

[0123] Furthermore, for the optical film, when heated from room temperature to 900°C at a rate of 10°C per minute, the temperature at which a 5% weight loss is measured by TGA is above 270°C, thus exhibiting excellent heat resistance.

[0124] The optical components of other specific embodiments of the aforementioned optical films or patterned films satisfy excellent optical properties, heat resistance, and mechanical properties, and therefore can be applied to various display devices, making a significant contribution to improving performance.

[0125] Therefore, according to yet another embodiment of the present invention, a display device including the optical components is provided.

[0126] The structure of a display device that uses optical components such as optical films or patterned films may have conventional structures well known in the art, except for those using optical components from other specific embodiments described above, and therefore their detailed description is omitted.

[0127] The following examples are provided to aid in understanding the present invention. However, the following examples are merely illustrative and the present invention is not limited to the following examples.

[0128] [Examples 1 to 309, Comparative Examples 1 to 44, and Reference Examples 1 to 9]

[0129] Preparation of photopolymerizable compositions and optical films

[0130] First, the monomers and components used to prepare the photopolymerizable compositions of the examples, comparative examples and reference examples are those listed in Tables 1 to 5 below.

[0131] [Table 1]

[0132] 1 benzyl acrylate 2 Phenoxyethyl acrylate 3 Phenoxybenzyl acrylate 4 methyl biphenyl acrylate 5 o-Phenoxyethyl acrylate 6 Chemical formula 1 (R=H) 7 <![CDATA[Chemical Formula 1 (R=CH₃)]]> 8 Chemical formula 2 (R=H) 9 <![CDATA[Chemical Formula 2 (R=CH₃)]]> 10 Chemical formula 3 (R=H) 11 <![CDATA[Chemical Formula 3 (R=CH₃)]]> 12 Chemical formula 4 (R=H) 13 <![CDATA[Chemical Formula 4 (R=CH₃)]]> 14 Chemical formula 5 (R=H) 15 <![CDATA[Chemical Formula 5 (R=CH₃)]]> 16 Chemical formula 6 (R=H) 17 <![CDATA[Chemical Formula 6 (R = CH₃)]]> 18 Chemical formula 7 (R=H) 19 <![CDATA[Chemical Formula 7 (R=CH₃)]]>

[0133] [Table 2]

[0134] 1 Isodecyl acrylate 2 Lauryl acrylate 3 Stearic acid 4 ethoxyethyl acrylate 5 ethoxyethyl acrylate 6 Triethylene glycol diacrylate 7 Tetraethylene glycol diacrylate 8 Dipropylene glycol diacrylate 9 Tripropylene glycol diacrylate 10 Chemical formula 8 (a, b = 0) 11 Chemical formula 8 (a, b = 2) 12 In chemical formula 8 (a+b>10)

[0135] [Table 3]

[0136] 1 1-[9-Ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-(O-acetyloxime) 2 OXE-01 3 OXE-04 4 Darocure TPO 5 (E)-2-(acetoxyimino)-1-(9,9-diethyl-9H-fluoren-2-yl)butanone 6 Irgacure 819 7 Irgacure 369 8 Irgacure 907

[0137] [Table 4]

[0138] 1 Ethyl dimethylaminobenzoate 2 Butoxyethyl dimethylaminobenzoate 3 Diethylaminoethyl methacrylate 4 P115 (provided by SK Cytec) 5 MIRAMER AS2010 (Provided by Miwon Commercial Co., Ltd) 6 MIRAMER AS5142 (Provided by Miwon Commercial Co., Ltd)

[0139] [Table 5]

[0140] 1 Isopropylthioxanone 2 9,10-Dibutoxyanthracene 3 9,10-Diethoxyanthracene 4 3,7-Dimethoxyanthracene

[0141] In addition, the components were mixed according to the components in Tables 6 to 14 below to prepare the photopolymerizable compositions of the Examples and Comparative Examples. In Tables 6 to 14, the units of content represent parts by weight.

[0142] After placing each photopolymerizable composition into an inkjet printer, it is coated onto bare glass to form a single film with a thickness of 20 μm.

[0143] Then, using an LED 385nm curing machine at 1.5J / cm 2 A single film was irradiated with an exposure amount to prepare a coating containing a photopolymerizable composition. This coating (thickness: 20 μm) was provided as an optical film. However, spin coating was performed to provide a 2 μm coating when determining the refractive index.

[0144] [Table 6]

[0145]

[0146]

[0147] [Table 7]

[0148]

[0149]

[0150] [Table 8]

[0151]

[0152]

[0153] [Table 9]

[0154]

[0155]

[0156] [Table 10]

[0157]

[0158]

[0159] [Table 11]

[0160]

[0161] [Table 12]

[0162]

[0163] [Table 13]

[0164]

[0165]

[0166] [Table 14]

[0167]

[0168]

[0169] [Experimental Example]

[0170] For the optical films prepared in the examples, comparative examples and reference examples, the refractive index, haze and viscosity and other physical properties were measured by the following methods, and the results are shown in Tables 15 to 22.

[0171] *Methods for determining the physical properties of optical films

[0172] 1) Sensitivity

[0173] The absorbance was measured using an FT-IR spectrophotometer by comparing the absorbance measurements before and after exposure. The absorbance was measured at 1650–1750 cm⁻¹. -1 The C=O peak value and 780–880 cm⁻¹ 1 The conversion rate is calculated by integrating the peak value of C=C. Sensitivity refers to the exposure level that saturates at a conversion rate of 80% or higher.

[0174] determination

[0175] ○: Sensitivity values ​​below 3J

[0176] X: Sensitivity value greater than 3J

[0177] 2) Refractive index

[0178] For the unrefined glass with the above-mentioned 2μm coating, the refractive index (average wavelength: 565nm, 555-575nm) was measured using an ellipsometry.

[0179] determination

[0180] ◎: The coating refractive index is 1.61 or higher.

[0181] ○: The coating refractive index is measured to be 1.58 or higher but less than 1.61.

[0182] X: Cases where the measured refractive index of the coating is less than 1.58.

[0183] 3) Transmittance

[0184] The average transmittance of the formed coating was measured using a UV-VIS spectrophotometer (Cary4000, Agilent) at 380–780 nm.

[0185] determination

[0186] ○: Cases where the average transmittance is 90% or higher

[0187] X: Case where the average transmittance value is less than 90%.

[0188] 4) Haze

[0189] The haze was measured using a COH 400 haze meter from Nippon Denshoku Corporation.

[0190] determination

[0191] ◎: Cases where the haze measurement value is less than 1.0

[0192] ○: Cases where the haze measurement value is between 1.0 and 3.0 or below.

[0193] X: Haze measurement value greater than 3.0

[0194] 5) Viscosity (absolute viscosity)

[0195] The viscosity of each photopolymerizable composition or olefin monomer in the above reference examples and embodiments was measured using a viscometer (trade name: Brookfield viscometer) at a temperature of 25°C.

[0196] determination

[0197] ○: Viscosity values ​​of 5 to 40 cP

[0198] X: Viscosity values ​​exceeding the above range

[0199] 6) Inkjet characteristics

[0200] Change the nozzle temperature of the inkjet equipment and confirm whether a surface is formed.

[0201] determination

[0202] The surface formed at a nozzle temperature of 25 to 35°C = ◎

[0203] The surface formed at a nozzle temperature of 35 to 50°C is ○.

[0204] No surface is formed at nozzle temperatures between 25 and 50°C.

[0205] 7) Flexible

[0206] For flexibility, measurements were performed using Instron's UTM. Specifically, a 20 μm thick sample (28 mm x 4 mm) was prepared, and the tensile strain was measured using Instron's UTM. Elongation was then evaluated using the tensile stress-strain curve obtained from the tensile strain.

[0207] determination

[0208] ◎: Cases where the tensile deformation rate is 10% or more (meaning that the elongation measured by the tensile stress-strain curve is 10% or more).

[0209] ○: The tensile deformation rate is 5% or more but less than 10% (meaning the elongation measured by the tensile stress-strain curve is 5% or more but less than 10%).

[0210] △: Cases where the tensile deformation rate is 1% or more but less than 5% (indicating that the elongation measured by the tensile stress-strain curve is 1% or more but less than 5%).

[0211] X: Cases where the tensile deformation rate is less than 1% (indicating that the elongation measured by the tensile stress-strain curve is less than 1%).

[0212] [Table 15]

[0213]

[0214]

[0215] [Table 16]

[0216]

[0217]

[0218]

[0219] [Table 17]

[0220]

[0221]

[0222] [Table 18]

[0223]

[0224]

[0225]

[0226] [Table 19]

[0227]

[0228]

[0229] [Table 20]

[0230]

[0231]

[0232] [Table 21]

[0233]

[0234]

[0235] [Table 22]

[0236]

[0237]

[0238] As shown in Tables 15 to 22 above, Examples 1 to 309, with their optimal configuration, contain a high-refractive-index monomer as a high-refractive-index monomer, a highly flexible monomer that prevents cracking, and a photoinitiator, etc. Therefore, compared with the comparative examples and reference examples, they have a higher refractive index, better viscosity, and exhibit low haze. In particular, compared with the comparative examples and reference examples, the above examples have better flexibility, and their sensitivity, transmittance, heat resistance, and inkjet processability are all excellent. When used as optical components in foldable or flexible display devices, they can help improve performance. In particular, Comparative Example 1, without the use of a highly flexible monomer, cannot exhibit softness characteristics. In addition, due to insufficient or excessive photoinitiator content, the sensitivity of Comparative Examples 2 and 3 could not be measured, or the initiator precipitation prevented the measurement of physical properties.

Claims

1. A photopolymerizable composition for use in highly flexible inkjet printing, comprising: a) One or more high refractive index monomers with a liquid refractive index of 1.51 or higher before curing; b) A highly flexible monomer of chemical formula 9 or above; and c) Photopolymerization initiator Based on a total weight of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the high-flexibility monomer comprises 10 to 40 parts by weight. Based on a total of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the photopolymerizable composition further comprises 0.1 to 10 parts by weight of an amine enhancer. The amine enhancer comprises one or more compounds selected from the group consisting of compounds of formula 11 below, bis(diethylamino)benzophenone, bis(2-hydroxyethyl)-toluidine, 2-(dimethylamino)ethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-(diisopropylamino)ethyl (meth)acrylate, 2-(dibutylamino)methacrylate, and 4,4-(oxobis(ethane-2,1-diyl))bis(oxo)bis(dimethylaniline). The absolute viscosity of the photopolymerizable composition, measured at 25°C, is between 5 cP and 40 cP. The photopolymerizable composition, after curing, has a haze of less than 3%, a refractive index of more than 1.58, and an elongation of more than 5%. [Chemical Formula 9] (A)mB-(A')n In the above chemical formula 9, A and A', as photocurable functional groups, can be the same or different. B, as an aliphatic structure with 6 to 50 carbon atoms, including or not including one or more oxygen atoms, must contain at least a straight-chain alkyl structure with 6 or more carbon atoms. m and n are integers of 0 or 1, and not both 0. [Chemical Formula 11] In the above chemical formula 11, R1 and R2 each independently represent an alkyl group having 1 to 5 carbon atoms, and R3 represents an alkyl group having 1 to 20 carbon atoms, an ether group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an amino group, or a (meth)acrylate group.

2. The photopolymerizable composition according to claim 1, wherein, The high refractive index monomer is an aromatic or alicyclic photocurable compound containing one or more aromatic rings or one or more heteroatoms.

3. The photopolymerizable composition according to claim 1, wherein, The high-refractive-index monomer is an aromatic or alicyclic photocurable compound comprising the structure of the following chemical formula 1: [Chemical Formula 1] B-Z1-Z2-R In the above chemical formula 1, B comprises any one or more of the following structures: an aryl group having 6 to 30 carbon atoms, a 5-7 membered aliphatic heterocyclic structure with one or more sulfur atoms (S) substituted, or a 5-7 membered aromatic heterocyclic structure with one or more sulfur atoms (S) substituted. Z1 is a direct bond or an alkylene group having 1 to 10 carbon atoms. Z2 is a direct bond or an alkylene group with 1 to 10 carbon atoms containing one or more oxygen (O) or sulfur (S), or a structure containing one or more oxygen (O) and an aromatic ring. R is a photocurable functional group.

4. The photopolymerizable composition according to claim 3, wherein, The high-refractive-index monomer comprises a structure of chemical formula 1, wherein B is an aryl group having 6 to 30 carbon atoms, Z1 is a direct bond, and Z2 is an alkylene group having 1 to 10 carbon atoms containing one or more oxygen atoms (O).

5. The photopolymerizable composition according to claim 3, wherein, The high-refractive-index monomer comprises a structure of chemical formula 1, wherein B is an aryl group having 6 to 30 carbon atoms, Z1 is a direct bond, and Z2 comprises one or more oxygen (O) atoms and an aromatic ring structure.

6. The photopolymerizable composition according to claim 3, wherein, The high refractive index monomer comprises a structure of chemical formula 1, wherein B comprises a 5-7 membered aromatic heterocyclic structure in which one or more sulfur (S) is substituted, Z1 is a direct bond, and Z2 is an alkylene group containing one or more sulfur (S) atoms with a carbon number of 1 to 10.

7. The photopolymerizable composition according to claim 1, wherein, The high refractive index monomer comprises one or more selected from the group consisting of benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, biphenyl ethyl (meth)acrylate, and the group consisting of chemical formulas 2 to 8: [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] [Chemical Formula 5] [Chemical Formula 6] [Chemical Formula 7] [Chemical Formula 8] In the above chemical formulas 2 to 8, R is independently H or CH3.

8. The photopolymerizable composition according to claim 1, wherein, The highly flexible monomer is B, which contains 4 to 20 oxygen atoms and has the chemical formula 9.

9. The photopolymerizable composition according to claim 1, wherein, The highly flexible monomer comprises one or more selected from the group consisting of isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and the following chemical formula 10. [Chemical Formula 10] In the above chemical formula 10, a + b = 0 ~ 10, where a and b are integers.

10. The photopolymerizable composition according to claim 9, wherein, In the above chemical formula 10, a and b are each integers from 1 to 5.

11. The photopolymerizable composition according to claim 1, wherein, Based on a total of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the photopolymerizable composition contains 0.5 to 30 parts by weight of a photopolymerization initiator.

12. The photopolymerizable composition according to claim 1, wherein, Based on a total of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer, the photopolymerizable composition further comprises 0.1 to 10 parts by weight of a photosensitizer.

13. The photopolymerizable composition according to claim 12, wherein, The photosensitizer is selected from one or more of the group consisting of isopropylthioxanthone, pyrene, perylene, triphenylene, anthracene, 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 3,7-dimethoxyanthracene, and 9,10-dipropoxyanthracene.

14. An optical component comprising: Base; and A cured film comprising a cured product of the highly flexible photopolymerizable composition for inkjet printing as described in any one of claims 1 to 13.

15. The optical component according to claim 14, wherein, The cured film has a haze of less than 3%, a refractive index of more than 1.58, and an elongation of more than 5%.

16. A display device comprising at least one of the optical components of claim 15 as an optical film or a patterned film.

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