Photopolymerizable composition, optical element and display device formed therefrom

Abstract

The present invention relates to a photopolymerizable composition capable of forming optical elements exhibiting improved optical properties including excellent high flexibility, high refractive index, optical transparency, and low haze, and having viscosity properties suitable for inkjet processing, and to optical elements and display devices formed therefrom.

Description

Technical Field

[0001] The present invention relates to a photopolymerizable composition in which not only optical properties including excellent light transmittance, low haze, and high refractive index but also mechanical physical properties including high flexibility and excellent bending reliability are simultaneously improved, an optical member formed therefrom, and a display device.

Background Art

[0002] In the case of a light-transmissive optical film having a structured prism, the rate of increase in luminance varies depending on the refractive index of the resin forming the prism structure. Generally, as the refractive index of the resin constituting the prism increases, the rate of increase in luminance increases. Therefore, research and development of the light-transmissive optical film are being advanced in the direction of increasing the refractive index of the resin forming the prism structure.

[0003] The high refractive index resin forming the prism is generally formed in a form in which a metal oxide is dispersed in an organic compound in order to ensure a high refractive index. However, although the refractive index is high due to the use of the metal oxide, there is a problem that the haze and reflectance also increase. When the reflectance is high, the outdoor visibility of the display decreases.

[0004] The shelf life of the product is determined by the dispersion stability of the resin formed in the form of the metal oxide dispersion, which makes mass production difficult and causes an increase in unit price. Further, in the case of the composition containing the metal oxide, problems such as an increase in viscosity and a decrease in inkjet processability are shown, and thus there are many technical restrictions.

[0005] Furthermore, when using existing general photopolymerizable compositions as monomer compositions to form the resin and optical film, surface hardening often did not occur sufficiently during the photocuring process of the monomer composition due to the influence of oxygen in the air. As a result, the resin and optical film experienced increased haze, leading to problems such as reduced light transmittance and visibility, including ultraviolet light transmittance. In addition, insufficient surface hardening reduced the mechanical properties of the film, significantly decreasing the high flexibility and bending reliability required for foldable devices. Therefore, considering the above problems, a method of performing the curing process under an inert gas atmosphere such as nitrogen was considered, but this resulted in a significant increase in manufacturing costs.

[0006] Recently, with the advancement of display-related technologies, deformable display devices that can be folded, rolled up, or stretched like a rubber band have been developed and mass-produced. Because these displays can be transformed into various forms, the materials used are also required to possess deformable mechanical properties.

[0007] However, due to the various problems mentioned above, while the material exhibits viscosity characteristics suitable for inkjet processes, development has not yet reached a satisfactory level in terms of excellent optical properties and high flexibility. Therefore, the development of technologies that enable the formation of optical films and other materials exhibiting excellent optical and mechanical properties is continuously needed. [Overview of the project] [Problems that the invention aims to solve]

[0008] Therefore, the present invention aims to provide a photopolymerizable composition that exhibits viscosity characteristics suitable for inkjet processes while suppressing the increase in haze during the curing process, thereby enabling the formation of optical components that simultaneously improve optical properties including excellent light transmittance, low haze, and high refractive index, as well as mechanical properties including high flexibility (elongation) and excellent bending reliability.

[0009] Furthermore, the present invention aims to provide an optical component formed from the aforementioned photopolymerizable composition, which has improved optical properties including excellent light transmittance, low haze, and high refractive index, as well as mechanical properties of high flexibility and excellent bending reliability. Furthermore, the present invention aims to provide a display device including the aforementioned optical element. [Means for solving the problem]

[0010] The present invention a) One or more high refractive index monomers having a liquid refractive index of 1.51 or higher before curing, b) One or more highly flexible monomers, c) A photopolymerizable composition comprising a photopolymerization initiator is provided. Furthermore, the present invention provides an optical component comprising a substrate and a cured film containing a cured product of the photopolymerizable composition. Furthermore, the present invention provides a display device that includes the aforementioned optical element. [Effects of the Invention]

[0011] The photopolymerizable composition according to the present invention exhibits viscosity characteristics suitable for inkjet processes while enabling the formation of cured films that satisfy a high refractive index and optical components containing them. Furthermore, specific highly flexible monomers contained in the photopolymerizable composition can improve the mechanical properties of the cured product, such as flexibility and bending reliability. In addition, the action of the amine synergist contained in the photopolymerizable composition can significantly reduce the problem of reduced surface hardness due to the influence of oxygen, resulting in the formation of optical components that exhibit low haze, excellent light transmittance such as ultraviolet transmittance, and high visibility. In addition, since the application of a nitrogen atmosphere or the like is unnecessary during the curing process of the photopolymerizable composition, the overall process economy can also be greatly improved.

[0012] Therefore, optical components formed from the photopolymerizable composition have a low manufacturing cost and exhibit low haze, high refractive index, excellent light transmittance and visibility, and excellent flexibility and bending properties, which can greatly contribute to improving the characteristics of foldable or flexible display devices. [Modes for carrying out the invention]

[0013] The present invention will now be described in more detail. The terms and words used herein and in the claims should not be interpreted in a manner limited to their ordinary or lexicographical meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may define the concepts of terms as appropriate to best describe their invention.

[0014] Furthermore, the meaning of "includes" as used in the specification of the present invention embodies a particular characteristic, domain, integer, stage, operation, element and / or component, and does not exclude the presence or addition of other characteristics, domains, integers, stages, operations, elements and / or components. In this specification, (meth)acrylate includes both acrylate and methacrylate.

[0015] The following describes examples in detail so that they can be easily implemented by a person with ordinary skill in the art. The examples can be implemented in various different forms and are not limited to the specific examples described herein.

[0016] According to one embodiment of the present invention, a photopolymerizable composition can be provided comprising: a) one or more high refractive index monomers having a liquid refractive index of 1.51 or higher before curing; b) one or more highly flexible monomers; and c) a photopolymerization initiator.

[0017] In one embodiment, the photopolymerizable composition can achieve high refractive index properties even without containing metal oxides, using only high refractive index monomers, and can prevent cracking of the cured film by including highly flexible monomers with excellent elongation. Therefore, optical components including a cured film formed by the photopolymerizable composition can be applied to foldable or flexible display devices to improve the performance of the display elements. Furthermore, even if the photopolymerizable composition contains only high refractive index monomers and highly flexible monomers, it can satisfy a viscosity range suitable for inkjet use and achieve excellent optical and mechanical properties for the cured product.

[0018] Since the photopolymerizable composition does not use metal oxides, it exhibits excellent surface hardening properties during the photocuring process, improving the haze characteristics, light transmittance, and visibility of optical films, and preventing factors that increase manufacturing costs. In particular, the use of the highly flexible monomer prevents cracking as described above, ensuring the excellent flexibility and bending reliability required for foldable or flexible devices. In addition, since the application of a nitrogen atmosphere or the like is unnecessary during the curing process of the photopolymerizable composition, the overall process economy can also be greatly improved.

[0019] Furthermore, the photopolymerizable composition can be made to further contain one or more components such as amine coordinators, photosensitizers, and surfactants to improve the surface curability for providing a cured film. For example, it has been confirmed that the action of the amine coordinator contained in the photopolymerizable composition can significantly reduce the problem of the decrease in surface hardness due to the influence of oxygen. This is thought to be because, during the curing process, the amine groups contained in the amine coordinator capture oxygen radicals in the air, thereby increasing 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 provide effects such as improving the uniformity of the film thickness and the smoothness of the surface.

[0020] Therefore, when the photopolymerizable composition of one embodiment, which may further contain components in addition to the above-described composition of the high refractive index monomer, the high flexibility monomer, and the photoinitiator, is photocured to form a cured film and an optical member, a high surface hardness can be achieved even in an air atmosphere, and the cured film and the like can exhibit low haze, excellent light transmittance such as ultraviolet transmittance, and high visibility. In particular, the photopolymerizable composition has greatly improved high flexibility and bending properties, shows a viscosity suitable for inkjet printing, and can improve processability such as coating and film formation. In addition, since the application of a nitrogen atmosphere or the like is not required during the curing process of the photopolymerizable composition, the overall process economy can also be greatly enhanced.

[0021] Therefore, by using the photopolymerizable composition, it is possible to form an optical member having a low production cost and exhibiting low haze, a high refractive index, high flexibility, excellent light transmittance, visibility, etc., which can greatly contribute to improving the characteristics of various types of display devices. Hereinafter, each component used in the photopolymerizable composition will be specifically described.

[0022] The photopolymerizable composition of one embodiment contains one or more high refractive index monomers, which are basic monomers for forming a cured film matrix and have a liquid refractive index before curing of 1.51 or more.

[0023] The high refractive index monomer can form a basic resin that forms a cured film by crosslinking polymerization of the photocurable functional group via a photoinitiator in the photocuring process described later. In particular, the high refractive index monomer can improve the refractive index of the cured film by ultraviolet irradiation or the like by satisfying a specific liquid crystal refractive index range. More specifically, the liquid refractive index of the high refractive index monomer before curing may be 1.51 to 1.60. If the liquid refractive index of the high refractive index monomer is 1.51 or less, there is a problem that the refractive index of the cured film becomes as low as 1.58 or less. The high refractive index monomer may be an aromatic or alicyclic photocurable compound containing one or more aromatic rings or one or more heteroatoms.

[0024] Specifically, the high refractive index monomer may be an aromatic or alicyclic photocurable compound having one or more aromatic rings or one or more heteroatoms in a photocurable functional group having 10 to 40 carbon atoms. More specifically, the high refractive index monomer may be an aromatic photocurable compound containing the structure of the following chemical formula 1: [Chemical formula 1] B-Z1-Z2-R

[0025] In the above chemical formula 1, B comprises one or more structures from among an aryl group having 6 to 30 carbon atoms, a 5 to 7-membered aliphatic heterocyclic structure substituted with one or more sulfur (S), or a 5 to 7-membered aromatic heterocyclic structure substituted with one or more sulfur (S). Z1 is either directly bonded or an alkyl group having 1 to 10 carbon atoms. Z2 is a C1-C10 alkyl group that is directly bonded or contains one or more oxygen (O) or sulfur (S). R is a photocurable functional group.

[0026] The high refractive index monomer may include the structure of Chemical Formula 1, in which 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.

[0027] The high refractive index monomer may include the structure of chemical formula 1 in which 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.

[0028] The high refractive index monomer may also include the structure of Chemical Formula 1, in which B comprises a 5-7 membered aromatic heterocyclic structure substituted with one or more sulfur (S), Z1 is a direct bond, and Z2 is a C1-C10 alkyl group containing one or more sulfur (S). The aforementioned high refractive index monomer may be in liquid form, but in the case of a structure containing anthracene or sulfur as represented by the chemical formula, it may exist in powder form rather than liquid form.

[0029] More specifically, the high refractive index monomers described above may include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, O-phenylphenoxyethyl (meth)acrylate, biphenylethyl (meth)acrylate, and one or more selected from the group consisting of chemical formulas 2 to 8. [Chemical formula 2] TIFF2023553373000001.tif38170[Chemical formula 3] TIFF2023553373000002.tif28170[Chemical formula 4] TIFF2023553373000003.tif43170[Chemical formula 5] TIFF2023553373000004.tif23170[Chemical formula 6] TIFF2023553373000005.tif67170[Chemical formula 7] TIFF2023553373000006.tif33170[Chemical formula 8] TIFF2023553373000007.tif37170 (In the above chemical formulas 2-8, R is independently either H or CH3.) In particular, when the high refractive index monomer has a structure containing anthracene and sulfur, a refractive index of 1.61 or higher can be ensured.

[0030] On the other hand, the highly flexible monomer according to the present invention hardens together with the high refractive index monomer, significantly improving the flexibility and bending properties of the hardened film and preventing cracks.

[0031] Specifically, the highly flexible monomer may include a compound having one or more photocurable functional groups that can improve the elongation of the final cured film by at least 5%.

[0032] The aforementioned elongation rate may have been measured by removing a 20 μm thick film from bare glass, preparing a dog bone test specimen (size: 28 mm × 4 mm), and then measuring the tensile stress-strain curve using an Instron UTM. The aforementioned highly flexible monomer may include the structure shown in the following chemical formula 9. [Chemical formula 9] (A)mB-(A')n

[0033] In the above chemical formula 9, A and A' are photocurable functional groups, which may or may not be the same, and B is an aliphatic structure having 6 to 50 carbon atoms, which may or may not contain one or more oxygen atoms, and which includes at least a linear alkyl structure having 6 or more carbon atoms. m and n are integers of 0 or 1. The aforementioned highly flexible monomer may have the structure of chemical formula 9, in which B contains 4 to 20 oxygen atoms.

[0034] 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.

[0035] More specifically, the highly flexible monomer may contain 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] TIFF2023553373000008.tif24170 (In the above chemical formula 10, a + b = 0 to 10, and a and b are integers.) In the chemical formula 10, a and b can each be integers from 1 to 5.

[0036] Such highly flexible monomers may be included in amounts of at least 10 parts by weight, based on a total of 100 parts by weight of the high refractive index monomer and the highly flexible monomer. Specifically, the highly flexible monomer can improve the flexibility of the cured film, which must be included in the photopolymerizable composition in amounts of 10 parts by weight or more.

[0037] More specifically, the high-flexibility monomer may be present in amounts of 10 to 90 parts by weight, based on a total of 100 parts by weight of the high-refractive-index monomer and the high-flexibility monomer. Alternatively, the high-flexibility monomer may be present in amounts of 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.

[0038] If the content of the highly flexible monomer is less than 10 parts by weight, the elongation rate after coating formation will be less than 5%, and flexibility cannot be improved. On the other hand, if the content of the highly flexible monomer is excessively high, such as 90 parts by weight or more, the refractive index will be low, and there is a problem in that a high refractive index of 1.58 or higher cannot be achieved.

[0039] The photopolymerizable composition of the above embodiment contains a photopolymerization initiator. Such a photopolymerization initiator can initiate and accelerate the photocuring reaction of the two specific monomers described above.

[0040] As such a photopolymerization initiator, any initiator that has been conventionally known to be able to initiate and promote the photocuring reaction of photocurable functional groups such as (meth)acrylate groups can be used.

[0041] Examples of the aforementioned photopolymerization initiators include one or more selected from the group consisting of triazine-based, benzoin-based, benzophenone-based, imidazole-based, xanthone-based, oxime ester-based, and acetophenone-based compounds.More specific examples of the aforementioned photopolymerization initiators include 2,4-bistrichloromethyl-6-p-methoxystyryl-s-triazine, 2-p-methoxystyryl-4,6-bistrichloromethyl-s-triazine, 2,4-trichloromethyl-6-triazine, 2,4-trichloromethyl-4-methylnaphthyl-6-triazine, 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, and 2-(o-chlorophenyl)-4,5-di(m- Methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methylphenyl) Lucaptophenyl)-4,5-diphenylimidazole dimer, [1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazoyl-3-yl]-1-(O-acetyloxime), 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-biimidazole, (E)-2-(acetoxyimino)-1-(9,9-diethyl-9H-fluoren-2-yl)butanone, (E)-1-(9,9-dibutyl-7-nitro-9H-fluoren-2-yl)ethanone O-acetyloxime, (Z)-2-(acetoxyimino)-1-(9,9-diethyl-9H-fluoren-2-yl)propanone, Irgacure Examples include compounds selected from the group consisting of 369, Irgacure 651, Irgacure 907, Darocur TPO, Irgacure 819, OXE-01, OXE-02, OXE-03, OXE-04, and Adecka's N-1919, NCI-831, and NCI-930, and other photopolymerization initiators known in the industry can be used without particular limitation.

[0042] The photopolymerizable composition may contain 0.5 to 30 parts by weight of a photopolymerization initiator based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. As another example, the photopolymerization initiator may be present in an amount of 0.6 to 28% by weight or 1 to 25% by weight based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. If the content of the photopolymerization initiator is too low, photocuring will not occur properly, and conversely, if the content is too high, the cumulative transmittance of the cured film will decrease to, for example, 90% or less.

[0043] On the other hand, the composition of one embodiment can have an absolute viscosity suitable for inkjet processes even without containing metal oxides, by using the high refractive index monomer and high flexibility monomer described above. Specifically, the absolute viscosity (measured at 25°C) of the photopolymerizable composition can be 5 cP to 40 cP. Therefore, the composition of one embodiment containing it has excellent inkjet processability, excellent heat resistance and mechanical properties, and enables the formation of a cured film with good coating film characteristics. Furthermore, due to the interaction between the olefin monomer and metal oxide particles, etc., described later, the cured film and optical component formed from the composition of one embodiment can have a high refractive index of 1.58 or higher.

[0044] For reference, the absolute viscosity described herein refers to the absolute viscosity value measured at 25°C, and such absolute viscosity can be measured using a viscometer well known in the art, such as a Brookfield viscometer.

[0045] On the other hand, a photopolymerizable composition of one embodiment may further contain one or more selected from the group consisting of d) an amine synergist having an amine group and a photocurable functional group, e) a photosensitizer, and f) a surfactant. Further inclusion of one or more additives from the above-mentioned components d) to f) can contribute to the photopolymerizable composition more effectively achieving its physical properties.

[0046] First, one embodiment of the photopolymerizable composition may contain an amine synergist having an amine group and a photocurable functional group. In the process of photocuring the composition of one embodiment to form a cured film and optical component, the amine group contained in such an amine synergist can capture oxygen radicals in the air and promote the reaction of the initiator. Furthermore, the photocurable functional group in the amine synergist can form crosslinked bonds with the monomer. Due to the action of such an amine synergist, the cured film and optical component formed from the composition of one embodiment can exhibit a high degree of surface hardness, and consequently exhibit excellent optical properties such as low haze and improved light transmittance. The amine coordinator may include one selected from the group consisting of compounds having a tertiary or higher amine group and a photopolymerizable acrylate group in its molecule.

[0047] Specifically, the amine cooperative can be any compound having a photocurable functional group, such as a (meth)acrylate group which is the same type of photocurable functional group as the monomer, along with an amine group in the molecule.

[0048] Specific examples of such amine synergies include one or more compounds selected from the group consisting of the following chemical formula 11: ethyldimethylaminobenzoate, butoxyethyldimethylaminobenzoate, bis(diethylamino)benzophenone, bis(2-hydroxyethyl)-toluidine, ethylhexyl-(dimethylamino)benzoate, 2-(dimethylamino)ethyl(meth)acrylate, diethylaminoethyl(meth)acrylate, 2-(diisopropylamino)ethyl(meth)acrylate, 2-(acryloyloxy)ethyl 4-(dimethylamino)benzoate, 2-ethylhexyl 4-(dimethylamino)benzoate, ethyl 2-(dibutylamino)methyl acrylate, and 4,4-(oxybis(ethane-2,1-diyl))bis(oxy)bis(dimethylaniline). Of course, a variety of other compounds having amine groups and photocurable functional groups can also be used. [Chemical formula 11] TIFF2023553373000009.tif42170

[0049] 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 amine group, or a (meth)acrylate group.

[0050] Furthermore, commercially available amine-based photocurable compounds can also be used as the amine synergist. Examples of such commercially available compounds include P115 (manufactured by SK Cytech Co., Ltd.), MIRAMER AS2010 (manufactured by Miwon Trading Co., Ltd.), or MIRAMER AS5142 (manufactured by Miwon Trading Co., Ltd.).

[0051] Furthermore, the photopolymerizable composition may further contain 0.1 to 10 parts by weight of an amine coordinator based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. As yet another example, the amine coordinator may be included in an amount of 0.5 to 9 parts by weight based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. If the content of the amine coordinator is excessively low, the degree of surface hardening decreases and the haze of the cured film and optical component increases. Conversely, if the content is excessively high, the viscosity of the photopolymerizable composition becomes excessively high, reducing processability or lowering the refractive index of the cured film, etc.

[0052] The aforementioned e) photosensitizer is included in the photopolymerizable composition and can further increase the curability of high refractive index monomers and high flexibility monomers, thereby improving haze properties and providing an effect of accelerating sensitivity.

[0053] As the photosensitizer, one or more can be selected from the group consisting of isopropylthioxanthone, pyrene, perylene, triphenylene, anthracene, 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 3,7-dimethoxyanthracene, and 9,10-dipropyloxyanthracene.

[0054] The photopolymerizable composition may further contain 0.1 to 10 parts by weight of a photosensitizer based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. As yet another example, the photosensitizer may be present in amounts of 0.5 to 9 parts by weight based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. If the content of the photosensitizer is too low, it will not contribute to improving the degree of surface hardening, and conversely, if the content is too high, the viscosity of the photopolymerizable composition will become too high, leading to problems such as reduced processability or reduced transmittance of the cured film.

[0055] The surfactant described in f) above can provide effects such as improving the uniformity of the film thickness and the smoothness of the surface. The surfactant may include one or more selected from the group consisting of silicone-based and fluorine-based surfactants.

[0056] The surfactant f) may be included in amounts of 0.1 to 5 parts by weight, based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. If the surfactant content is too low, problems arise such as poor film thickness uniformity and surface smoothness, while conversely, if the content is too high, problems arise such as the formation of air bubbles inside the film or a decrease in inkjet ejection characteristics.

[0057] On the other hand, the photopolymerizable composition of one embodiment may further contain a dispersant in addition to the components described above, if necessary. Such a dispersant can be included in the photopolymerizable composition described above and can improve the dispersion stability of the other components.

[0058] The type of dispersant is not particularly limited, and any dispersant known to be usable for improving 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.

[0059] The dispersant is included in an amount of 0.1 to 30 parts by weight, or 0.5 to 20 parts by weight, based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. Depending on the amount of the dispersant, each component is dispersed more uniformly, and the desired refractive index range of the cured film can be achieved more effectively. However, if the amount of dispersant is excessively high, the viscosity of the photopolymerizable composition will increase, and the inkjet processability will decrease.

[0060] Furthermore, the composition of the above-described embodiment can be manufactured in a solvent-free form without the use of a separate solvent or liquid medium. This further improves the processability when using the composition of the above-described embodiment.

[0061] As described above, the photopolymerizable composition of one embodiment containing the components described above may have an absolute viscosity (measured at 25°C) of 5 to 40 cP or 5 cP to 30 cP. The absolute viscosity can be measured using a conventionally known viscosity measuring device, such as a Brookfield viscometer. By satisfying this viscosity range, the photopolymerizable composition of one embodiment enables the formation of a cured film with excellent heat resistance and mechanical properties, as well as excellent inkjet processability and good coating film formation by the inkjet process.

[0062] If the viscosity of the final composition is excessively low, nozzle drying and clogging may occur, leading to a decrease in discharge characteristics. Conversely, if the viscosity of the composition is excessively high, problems such as reduced discharge volume and inability to form patterns and surfaces may arise.

[0063] On the other hand, according to another embodiment of the present invention, a cured film containing a cured product of the above-described photopolymerizable composition and an optical member containing the same are provided. Such an optical member may include a substrate and the cured film formed on the substrate. Furthermore, the cured film may mainly consist of a polymer containing units in which the photocurable functional groups of the olefin monomer and the amine copolymer are crosslinked, formed by photocuring after the photopolymerizable composition of one embodiment is applied to the substrate by an inkjet process, and a cured product containing a dispersant and a metal oxide dispersed on the polymer.

[0064] More specifically, the cured product comprises an olefin resin crosslinked by curing a high refractive index monomer and a high flexibility monomer, and the olefin resin can be selectively further crosslinked with the photocurable functional group of the amine copolymer. Furthermore, the olefin resin can be improved in terms of photopolymerizability and film properties when combined with one or more selected from the group consisting of the photosensitizers and surfactants described above. In this case, the olefin resin is a polymer crosslinked from a high refractive index monomer having one or more photocurable functional groups and one or more high flexibility monomers, and its form is not particularly limited, and depending on the type of monomer and the polymerization reaction mechanism described above, it can have various forms such as homopolymers, block copolymers, random copolymers or graft copolymers. On the other hand, according to another embodiment of the present invention, an optical member may be provided that includes a substrate and a cured film containing a cured product of the above-described highly flexible photopolymerizable composition for inkjet printing.

[0065] The cured film containing the cured material described above can exhibit excellent heat resistance and mechanical properties, as well as good coating characteristics, by being formed from a photopolymerizable composition of one embodiment having a viscosity suitable for inkjet processes. Furthermore, the cured film may have a haze of 3% or less, a refractive index of 1.58 or more, and an elongation of 5% or more.

[0066] Specifically, the cured film may have a refractive index of 1.58 or higher after photopolymerization, with reference to a wavelength of 565 nm. More specifically, the cured film has a high refractive index of 1.6 or higher, or 1.6 to 2.0, or 1.6 to 1.65. In this case, the refractive index refers to the value measured using an ellipsometer for a wavelength of 555 to 575 nm (average).

[0067] Furthermore, the amine synergist exhibits a high degree of surface hardening, resulting in low haze levels such as 3% or less, 1% or less, 0-1%, 0.01-0.8%, or 0.1-0.3%, as well as excellent light transmittance and visibility, including high ultraviolet transmittance.

[0068] Furthermore, the cured film may have an elongation of 5% or more, or 5-10%, or 10% or more, as measured by the tensile stress-strain curve of a dog bone test specimen (size: 28 mm x 4 mm) prepared by removing a 20 μm thick film from bare glass and measuring it using an Instron UTM. In the optical components described above, a well-known substrate such as bare glass can be used as the substrate.

[0069] Furthermore, the optical component can be manufactured by applying the photopolymerizable composition of the above embodiment onto the substrate using a Mayer bar, a coating applicator, or an inkjet device, and then photocuring it by exposure using an LED lamp or a metal halide lamp in an air atmosphere, for example. In this case, the photopolymerizable composition may be applied in a single-film form and then photocured to form an optical component in the form of a general optical film, or it may be applied using the inkjet device to have a certain pattern form and then photocured as needed. In this case, the optical component may be in the form of a patterned film on the substrate, in which a cured film patterned in a polyhedral form such as a prism structure is formed.

[0070] The optical components described above, such as optical films or pattern films, may have a general thickness depending on their type and the structure of the display element to which they are applied, and for example, they may have a thickness that can be adjusted within the range of 0.01 μm to 1000 μm.

[0071] Furthermore, the optical element may have a sensitivity value of 3 J or less and a light transmittance of 90% or more. The sensitivity can be measured by comparing the absorbance measurement results before and after exposure using an FT-IR spectrophotometer. More specifically, 1650-1750 cm⁻¹ -1 The C=O peak and 780-880cm -1The conversion rate is determined by integrating the C=C peak, and sensitivity refers to the exposure amount at which the conversion rate saturates at 80% or higher. Furthermore, the light transmittance refers to the average transmittance measured at wavelengths of 380 to 780 nm using a UV-VIS spectrophotometer for optical materials such as optical films.

[0072] Furthermore, the optical film can be heated from room temperature to 900°C at a rate of 10°C per minute, and the 5% wt Loss temperature measured by TGA can reach 270°C or higher, demonstrating excellent heat resistance.

[0073] The optical components of other embodiments, such as the optical film or pattern film described above, satisfy excellent optical properties, heat resistance, and mechanical properties, and can be applied to various display devices, greatly contributing to the improvement of their properties. Thus, according to yet another embodiment of the present invention, a display device including the optical member is provided.

[0074] The configuration of a display device to which the optical component such as the optical film or pattern film is applied can follow a common configuration known in the industry, except that the optical component of the other embodiments described above is applied, so no further explanation is provided therein.

[0075] Examples are provided below to aid in understanding the present invention. However, the following examples are merely illustrative of the present invention and are not limited thereto.

[0076] [Examples 1-309, Comparative Examples 1-44, and Reference Examples 1-9] Production of photopolymerizable compositions and optical films First, the monomers and components listed in Tables 1 to 5 below were used as the components for the production of the photopolymerizable compositions in the examples, comparative examples, and reference examples.

[0077] [Table 1]

[0078] [Table 2]

[0079] [Table 3]

[0080] [Table 4]

[0081] [Table 5]

[0082] Then, the photopolymerizable compositions of the examples and comparative examples were prepared by mixing each component according to the compositions shown in Tables 6 to 14 below. In Tables 6 to 14, the units of each content are parts by weight. After each photopolymerizable composition was introduced into an inkjet device, it was coated onto bare glass to form a single film with a thickness of 20 μm.

[0083] Subsequently, a 385nm LED curing device was used to cure the temperature at 1.5 J / cm². 2 A coated film containing a cured product of a photopolymerizable composition was manufactured by irradiating a single film with the specified exposure level. Such a coated film (thickness: 20 μm) was provided as an optical film. However, for refractive index measurements, a 2 μm coated film was provided by spin coating.

[0084] [Table 6] TIFF2023553373000016.tif228170

[0085] [Table 7] TIFF2023553373000018.tif228170

[0086] Table 8 TIFF2023553373000020.tif228170

[0087] Table 9 TIFF2023553373000022.tif255170TIFF2023553373000023.tif255170TIFF2023553373000024.tif255170

[0088] Table 10 TIFF2023553373000026.tif208170

[0089] Table 11

[0090] Table 12 TIFF2023553373000029.tif255170TIFF2023553373000030.tif225170

[0091] Table 13 TIFF2023553373000032.tif212170

[0092] Table 14 TIFF2023553373000034.tif255166TIFF2023553373000035.tif123170

[0093] [Example of experiment] The optical films of the examples, comparative examples, and reference examples manufactured above were subjected to measurements of physical properties such as refractive index, haze, and viscosity using the following methods, and the results are shown in Tables 15 to 22. *Method for measuring the physical properties of optical films 1) Sensitivity The absorbance before and after exposure was measured using an FT-IR spectrophotometer and compared. (1650-1750 cm⁻¹) -1 The C=O peak and 780-880cm -1 The conversion rate is obtained by integrating the C=C peak, and sensitivity refers to the exposure level at which the conversion rate saturates at 80% or higher. judgement ○: When the sensitivity value is 3J or less X: If the sensitivity value exceeds 3J 2) Refractive index The refractive index (wavelength 555-575 nm, average: 565 nm) was measured using an ellipsometer on the bare glass on which the 2 μm coating film was formed. judgement ◎: When the refractive index measurement of the coating film is 1.61 or higher. ○: When the measured refractive index of the coating film is 1.58 or higher and less than 1.61. X: When the refractive index measurement of the coating film is less than 1.58 3) Transparency The average transmittance of the formed coating film was measured at 380-780 nm using a UV-VIS spectrophotometer (Cary4000, Agilent). judgement ○: When the average transmittance value is 90% or higher X: When the average transmittance value is less than 90% 4) Hayes The haze was measured using a COH 400 haze meter manufactured by NIPPON DENSHOKU. judgement ◎: When the haze measurement is less than 1.0 ○: When the haze measurement is between 1.0 and 3.0 or less. X: When the haze measurement is greater than 3.0 5) Viscosity (absolute viscosity)

[0094] The viscosity of each photopolymerizable composition or olefin monomer in the above-mentioned reference examples and examples was measured at a temperature of 25°C using a viscometer (product name: Brook Field viscometer). judgement ○: When the viscosity value is between 5 and 40 cP X: When the viscosity value falls outside the above range. 6) Inkjet characteristics We checked whether surface formation was possible while changing the nozzle temperature of the inkjet device. judgement Surface formation at nozzle temperature below 25-35°C = ◎ Surface formation at nozzle temperature of 35-50°C = ○ Surface formation is not possible at nozzle temperatures of 25-50°C = X 7)Flexibility Flexibility was measured using an Instron UTM. Specifically, a 28mm x 4mm sample with a thickness of 20μm was fabricated, and the tensile strain was measured using an Instron UTM. Subsequently, the elongation was evaluated from the tensile stress-strain curve obtained from the tensile strain. judgement ◎: Tensile Strain 10% or more (This means that the elongation measured by the tensile stress-strain curve is 10% or more.) ○: Tensile Strain 5% or more but less than 10% (This means that the elongation measured by the tensile stress-strain curve is 5% or more but less than 10%.) △: Tensile Strain 1% or more but less than 5% (This means that the elongation measured by the tensile stress-strain curve is 1% or more but less than 5%.) X: Tensile Strain less than 1% (meaning the elongation measured by the tensile stress-strain curve is less than 1%).

[0095] [Table 15] TIFF2023553373000037.tif219170

[0096] [Table 16] TIFF2023553373000039.tif219170

[0097] [Table 17] TIFF2023553373000041.tif219170

[0098] [Table 18] TIFF2023553373000043.tif250167TIFF2023553373000044.tif20170

[0099] [Table 19] TIFF2023553373000046.tif175170

[0100] [Table 20] TIFF2023553373000048.tif250167TIFF2023553373000049.tif47170

[0101] [Table 21] TIFF2023553373000051.tif84170

[0102] [Table 22] TIFF2023553373000053.tif211170

[0103] As can be seen from the results in Tables 15-22 above, Examples 1-309 were found to exhibit higher refractive index, better viscosity, and lower haze compared to the Comparative Examples and Reference Examples by optimally incorporating high refractive index monomers and highly flexible monomers that can prevent cracking together with high refractive index monomers and photoinitiators. In particular, the above examples were even more flexible than the Comparative Examples and Reference Examples, and were superior not only in sensitivity, transmittance, and heat resistance, but also in inkjet processability, and are considered to contribute to performance improvement when applied as optical components in foldable or flexible display devices. In particular, it was found that when the highly flexible monomer was not used in Comparative Example 1, the flexibility characteristics could not be exhibited. Also, in Comparative Examples 2 and 3, the photoinitiator content was either excessively low or excessive, making it impossible to measure sensitivity or to measure physical properties due to precipitation of the initiator.

Claims

1. a) One or more high refractive index monomers selected such that the refractive index of the cured film is 1.58 or higher, and which are aliphatic or aromatic photocurable compounds containing the structure of the following chemical formula 1, and which have a liquid refractive index of 1.51 or higher before curing. b) One or more highly flexible monomers selected from the group consisting of the following chemical formula 10, c) A highly flexible photopolymerizable composition for inkjet use comprising a photopolymerization initiator, The refractive index of the cured film was measured using an ellipsometer at an average wavelength of 555 to 575 nm on bare glass on which a 2 μm coated film was formed. The high-flexibility monomer comprises 10 to 90 parts by weight based on 100 parts by weight of the total sum of the high-refractive-index monomer and the high-flexibility monomer, and the photopolymerizable composition further comprises a photosensitizer; and a mixture of an amine synergist having an amine group and a photocurable functional group. The content of the photosensitizer and the amine coordinator is 0.1 to 10 parts by weight, respectively, based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer. The photosensitizer is one or more selected from the group consisting of isopropylthioxanthone, pyrene, perylene, triphenylene, anthracene, 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 3,7-dimethoxyanthracene, and 9,10-dipropyloxyanthracene. The amine coordinator is one or more compounds selected from the group consisting of the following chemical formula 11, ethyldimethylaminobenzoate, butoxyethyldimethylaminobenzoate, bis(2-hydroxyethyl)-toluidine, 2-(acryloyloxy)ethyl 4-(dimethylamino)benzoate, 2-ethylhexyl 4-(dimethylamino)benzoate, and 4,4-(oxybis(ethane-2,1-diyl))bis(oxy)bis(dimethylaniline), and is a photopolymerizable composition. [Chemical formula 1] B-Z1-Z2-R In the above chemical formula 1, B comprises one or more structures from among an aryl group having 6 to 30 carbon atoms, a 5 to 7-membered aliphatic heterocyclic structure substituted with one or more sulfur (S), or a 5 to 7-membered aromatic heterocyclic structure substituted with one or more sulfur (S). Z1 is either a direct bond or an alkylene group having 1 to 10 carbon atoms. Z2 is either a directly bonded alkylene group having 1 to 10 carbon atoms containing one or more oxygen (O) or sulfur (S), or a structure containing both one or more oxygen (O) and an aromatic ring structure. R is a photocurable functional group, [Chemical formula 10] In the aforementioned chemical formula 10, a and b are each integers from 1 to 5. [Chemical formula 11] In the above chemical formula 11, R １ and R ２ Each independently represents an alkyl group having 1 to 5 carbon atoms, R ３ This 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 amine group, or a (meth)acrylate group.

2. The photopolymerizable composition according to claim 1, wherein the high refractive index monomer comprises the structure of chemical formula 1, in which 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 (O) atoms.

3. The photopolymerizable composition according to claim 2, wherein the high refractive index monomer comprises a structure of chemical formula 1 in which 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.

4. The photopolymerizable composition according to claim 1, wherein the high refractive index monomer comprises a structure of chemical formula 1 in which B comprises a 5- to 7-membered aromatic heterocyclic structure in which one or more sulfur (S) atoms are substituted, Z1 is a direct bond, and Z2 is a C1- to C10 alkylene group containing one or more sulfur (S) atoms.

5. The photopolymerizable composition according to claim 1, wherein the high refractive index monomer comprises benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, O-phenylphenoxyethyl (meth)acrylate, biphenylethyl (meth)acrylate, and one or more selected from 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 either H or CH) ３ (is)

6. The photopolymerizable composition according to claim 1, wherein the highly flexible monomer comprises 10 to 40 parts by weight based on 100 parts by weight of the total sum of the highly refractive index monomer and the highly flexible monomer.

7. The photopolymerizable composition according to claim 1, comprising 0.5 to 30 parts by weight of a photopolymerization initiator based on 100 parts by weight of the total sum of the high refractive index monomer and the high flexibility monomer.

8. The photopolymerizable composition according to claim 1, wherein the absolute viscosity (measured at 25°C) of the photopolymerizable composition is 5 cP to 40 cP.

9. Substrate and An optical member comprising a cured film containing a cured product of a highly flexible photopolymerizable composition for inkjet use according to any one of claims 1 to 8.

10. The haze of the cured film is 3% or less, the refractive index is 1.58 or higher, and the elongation is 5% or higher. The optical member according to claim 9, wherein the refractive index of the cured film is measured at an average wavelength of 555 to 575 nm using an ellipsometer on bare glass on which a 2 μm coated film is formed.

11. A display device comprising the optical member described in claim 9 as at least one of an optical film or a pattern film.

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