Photocurable composition and protective film comprising same

Abstract

The present invention relates to a photocurable composition comprising an oligomer syrup, a second monomer mixture, and a photoinitiator, and being capable of providing a protective film having excellent impact resistance and folding properties, and to a protective film comprising a cured product thereof.

Description

Photocurable composition and protective film comprising the same

[0001] The present invention relates to a photocurable composition and a protective film comprising the same.

[0002]

[0003] Recently, the use of OLED display devices utilizing flexible, foldable, and rollable technologies has increased, and their applications are expanding. Consequently, the components used as cover windows in products employing these display devices are also increasingly demanding improved performance.

[0004] Colorless Polyimide (CPI) films, which were applied as cover windows for mobile products including early foldable smartphones, had problems such as scratches, lifting, poor touch response, poor surface smoothness, and failure to protect the panel from external impact when folding.

[0005] To address this issue, ultra-thin tempered glass (UTG) has been recently adopted, which has solved many problems. However, foldable glass with such a thin thickness still has the problem of being vulnerable to external impacts, and thus, technological development is needed to address this issue.

[0006]

[0007] The present invention provides a photocurable composition capable of implementing a protective film having excellent impact resistance and folding properties, and a protective film including a cured product thereof.

[0008] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0009]

[0010] One embodiment of the present invention provides a photocurable composition comprising: an oligomer syrup comprising a urethane (meth)acrylate oligomer which is a reaction product of a first monomer mixture comprising a diisocyanate compound, a polydiol compound containing a double bond in a repeating unit, and a hydroxyl group-containing (meth)acrylate compound; a second monomer mixture comprising one or more reactive monomers; and a photoinitiator.

[0011] According to one embodiment of the present invention, it may be a reaction product of a urethane prepolymer, which is a reaction product of a mixture containing the diisocyanate compound and the polydiol compound, and the hydroxyl group-containing (meth)acrylate compound.

[0012] According to one embodiment of the present invention, the weight average molecular weight of the urethane (meth)acrylate oligomer may be 38,000 g / mol or more, and the number average molecular weight may be 10,500 g / mol or more.

[0013] According to one embodiment of the present invention, the weight ratio of the diisocyanate compound and the polydiol compound may be 1:10.5 to 1:20.

[0014] According to one embodiment of the present invention, the second monomer mixture includes a (meth)acrylamide-based first monomer, and the content of the first monomer may be 10 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

[0015] According to one embodiment of the present invention, the second monomer mixture includes a pyrrolidone-based second monomer, and the content of the second monomer may be 15 parts by weight or more and 35 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

[0016] According to one embodiment of the present invention, the second monomer mixture includes a third monomer containing a heterocyclic group having 3 to 8 carbon atoms and containing nitrogen and oxygen, and the content of the third monomer may be 10 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

[0017] According to one embodiment of the present invention, the second monomer mixture includes a fourth monomer containing a cycloalkyl group having 5 to 10 carbon atoms, and the content of the fourth monomer may be 5 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

[0018] According to one embodiment of the present invention, the second monomer mixture includes a fifth monomer of the (meth)acrylate type containing a heterocyclic group having 4 to 9 oxygen-containing carbon atoms, and the content of the fifth monomer may be 5 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

[0019] According to one embodiment of the present invention, the second monomer mixture includes two (meth)acrylate group-containing sixth monomers, and the content of the sixth monomer may be 15 parts by weight or more and 35 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

[0020] According to one embodiment of the present invention, the second monomer mixture includes a seventh monomer containing three or more (meth)acrylate groups, and the content of the seventh monomer may be 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

[0021] According to one embodiment of the present invention, the content of the photoinitiator may be 1 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

[0022] One embodiment of the present invention provides a protective film including a cured product of the photocurable composition.

[0023] According to one embodiment of the present invention, the protective film may be a protective film for a display device.

[0024]

[0025] A photocurable composition according to one embodiment of the present invention can implement a protective film with excellent impact resistance and folding properties.

[0026] In addition, the photocurable composition according to one embodiment of the present invention can implement a protective film exhibiting excellent folding properties even under high temperature and high humidity conditions.

[0027] In addition, the photocurable composition according to one embodiment of the present invention can implement a protective film that is easy to print on a surface.

[0028] In addition, the protective film according to one embodiment of the present invention has the advantage of excellent impact resistance and folding properties, and easy printing on the surface.

[0029] However, the effects of the present invention are not limited to the above-described effects, and may be expanded in various ways without departing from the spirit and scope of the present invention.

[0030]

[0031] Throughout this specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0032] Throughout this specification, when it is said that an element is “connected” to another element, this includes not only cases where the element is directly connected to the other element, but also cases where another element exists between the two elements to connect them.

[0033] Throughout this specification, when it is said that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the two elements.

[0034] Throughout this specification, terms including ordinal numbers, such as "first" and "second," are used to distinguish one component from another and are not limited by the ordinal numbers. For example, within the scope of the invention, the first component may also be referred to as the second component, and similarly, the second component may be referred to as the first component.

[0035] Throughout this specification, “At least one of a, b and c” may include a, b or c alone, or a combination of two or more selected from the group consisting of a, b and c.

[0036] Throughout this specification, “A and / or B” means “A and B, or A or B.”

[0037] Throughout this specification, the unit “parts by weight” may mean the weight ratio between each component.

[0038] Throughout this specification, “(meth)acrylate” is used to refer to both acrylate and methacrylate.

[0039] Throughout the present specification, the “weight average molecular weight” and “number average molecular weight” of a compound can be calculated using the molecular weight and molecular weight distribution of the compound. Specifically, a sample having a concentration of 1 wt% of the compound is prepared by adding tetrahydrofuran (THF) and the compound to a 1 ml glass bottle, and a standard sample (polystyrene) and the sample sample are filtered through a filter (pore size: 0.45 ㎛), and then injected into a GPC injector. The elution time of the sample sample is compared with the calibration curve of the standard sample, thereby obtaining the molecular weight and molecular weight distribution of the compound. At this time, Infinity II 1260 (Agilient) can be used as the measuring device, and the flow rate can be set to 1.00 mL / min and the column temperature to 40.0°C.

[0040] Throughout this specification, the viscosity of a solution can be measured using a Brookfield viscometer at a specific temperature.

[0041]

[0042] Hereinafter, the present specification will be described in more detail.

[0043] One embodiment of the present invention provides a photocurable composition comprising: an oligomer syrup comprising a urethane (meth)acrylate oligomer which is a reaction product of a first monomer mixture comprising a diisocyanate compound, a polydiol compound containing a double bond in a repeating unit, and a hydroxyl group-containing (meth)acrylate compound; a second monomer mixture comprising one or more reactive monomers; and a photoinitiator.

[0044] A photocurable composition according to one embodiment of the present invention can produce a protective film with excellent impact resistance and foldability. Furthermore, the photocurable composition can produce a protective film that exhibits excellent foldability even under high temperature and high humidity conditions. Furthermore, the photocurable composition can produce a protective film that is easy to print on its surface.

[0045] According to one embodiment of the present invention, the photocurable composition comprises the urethane (meth)acrylate oligomer and a specific type of reactive monomer, thereby enabling a protective film having excellent impact resistance and foldability to be realized after curing.

[0046] According to one embodiment of the present invention, the urethane (meth)acrylate oligomer may be a reaction product of a first monomer mixture including the diisocyanate compound, the polydiol compound, and the hydroxyl group-containing (meth)acrylate compound. Specifically, a urethane bond may be formed by a reaction between an isocyanate group provided at one terminal of the diisocyanate compound and a hydroxyl group provided at the terminal of the polydiol compound. In addition, a urethane bond may be formed by a reaction between an isocyanate group provided at the other terminal of the diisocyanate compound and a hydroxyl group provided at the terminal of the hydroxyl group-containing (meth)acrylate compound. By including the urethane (meth)acrylate oligomer including the urethane bond, the photocurable composition can easily provide a protective film having excellent impact resistance and folding properties and surface properties suitable for printing after photocuring. Specifically, the cured product of the photocurable composition does not cause cracks, lifting, wrinkles, etc. even when deformed by folding, rolling, etc., and can have excellent impact resistance to external impact.

[0047] According to one embodiment of the present invention, the urethane (meth)acrylate-based oligomer may be a reaction product of a urethane prepolymer, which is a reaction product of a mixture containing the diisocyanate-based compound and the polydiol-based compound, and the hydroxyl group-containing (meth)acrylate-based compound. Meanwhile, in order to manufacture the urethane (meth)acrylate-based oligomer, a hydroxyl group-containing (meth)acrylate-based compound may be reacted with an excess of a diisocyanate-based compound to synthesize a urethane prepolymer in which an isocyanate group remains at one terminal, and a polydiol-based compound may be reacted therewith. However, by first reacting the diisocyanate-based compound and the polydiol-based compound, the weight average molecular weight and number average molecular weight of the urethane (meth)acrylate-based oligomer can be more easily controlled, and there is an advantage in that the amount of the diisocyanate-based compound used can be reduced.

[0048] According to one embodiment of the present invention, the weight average molecular weight of the urethane (meth)acrylate-based oligomer may be 38,000 g / mol or more, and the number average molecular weight may be 10,500 g / mol or more. Specifically, the weight average molecular weight of the urethane (meth)acrylate-based oligomer may be 38,000 g / mol or more and 60,000 g / mol or less, 40,000 g / mol or more and 50,000 g / mol or less, 42,000 g / mol or more and 48,000 g / mol or less, 38,000 g / mol or more and 50,000 g / mol or less, or 44,000 g / mol or more and 60,000 g / mol or less. In addition, the number average molecular weight of the urethane (meth)acrylate oligomer may be 10,500 g / mol or more and 20,000 g / mol or less, 12,000 g / mol or more and 15,000 g / mol or less, 10,500 g / mol or more and 14,000 g / mol or less, or 15,000 g / mol or more and 20,000 g / mol or less.

[0049] When the weight average molecular weight and / or number average molecular weight of the above urethane (meth)acrylate oligomer is within the above-mentioned range, the cured product of the photocurable composition may have excellent impact resistance and folding properties, and may have excellent surface printing properties. Specifically, the cured product of the photocurable composition may not cause cracks, lifting, wrinkles, etc. even when deformed by folding, rolling, etc., and may have excellent impact resistance to external impact.

[0050] According to one embodiment of the present invention, the diisocyanate-based compound may include at least one of bis(isocyanatomethyl)cyclohexane, methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, meta-xylene diisocyanate, dicyclohexylmethane diisocyanate, and tetramethyl xylene diisocyanate. Specifically, the diisocyanate-based compound may contain a cycloalkylene having 5 to 10 carbon atoms. More specifically, the diisocyanate-based compound may include at least isophorone diisocyanate. By using a diisocyanate-based compound containing a cycloalkylene having 5 to 10 carbon atoms, the photocurable composition may have excellent impact resistance and folding properties after curing.

[0051] According to one embodiment of the present invention, the polydiol-based compound may contain a double bond within the repeating unit. Specifically, the polydiol-based compound may contain a double bond in the main chain within the repeating unit. In addition, the polydiol-based compound may contain a double bond in a side chain bonded to the main chain within the repeating unit. More specifically, the polydiol-based compound may include at least one of polybutadiene diol and polyisoprene diol. By using a polydiol-based compound containing a double bond within the repeating unit, the cured product of the photocurable composition may have excellent impact resistance and folding properties, and excellent surface printing characteristics.

[0052] According to one embodiment of the present invention, the polydiol compound may have a number average molecular weight of 2,500 g / mol or more and 6,000 g / mol or less, 3,000 g / mol or more and 4,000 g / mol or less, 2,500 g / mol or more and 4,000 g / mol or less, or 3,000 g / mol or more and 6,000 g / mol or less. When the number average molecular weight of the polydiol compound is within the above-mentioned range, the photocurable composition may have excellent impact resistance and folding properties after curing.

[0053] According to one embodiment of the present invention, the hydroxyl group-containing (meth)acrylate compound may include at least one of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, and 2-hydroxypropylene glycol (meth)acrylate. By using the above-described type of hydroxyl group-containing (meth)acrylate compound, the photocurable composition can implement excellent mechanical properties and foldability under high temperature and high humidity conditions after curing, and can have excellent surface printing characteristics.

[0054] According to one embodiment of the present invention, when producing the urethane (meth)acrylate-based oligomer, the molar ratio of the diisocyanate-based compound and the polydiol-based compound may be 1:0.5 to 1:1. When the molar ratio of the diisocyanate-based compound and the polydiol-based compound is within the above-mentioned range, the urethane bond between the diisocyanate-based compound and the polydiol-based compound can be stably performed, and an appropriate level of average urethane bond number can be formed in the urethane (meth)acrylate-based oligomer.

[0055] According to one embodiment of the present invention, the weight ratio of the diisocyanate-based compound and the polydiol-based compound may be 1:10.5 to 1:20, 1:10.5 to 1:17.5, or 1:10.5 to 1:15. When the weight ratio of the diisocyanate-based compound and the polydiol-based compound is within the above-mentioned range, the urethane bond between the diisocyanate-based compound and the polydiol-based compound can be stably performed, and an appropriate level of average urethane bond number can be formed in the urethane (meth)acrylate-based oligomer. In addition, by adjusting the weight ratio of the diisocyanate-based compound and the polydiol-based compound within the above-mentioned range, a photocurable composition having excellent impact resistance and folding properties after curing and excellent surface printing characteristics can be provided. In addition, a protective film including a cured product of the photocurable composition may not cause cracks, lifting, or wrinkles even when deformed by folding, rolling, or the like, and may have excellent impact resistance to external impact.

[0056] According to one embodiment of the present invention, when producing the urethane (meth)acrylate-based oligomer, the molar ratio of the diisocyanate-based compound and the hydroxyl group-containing (meth)acrylate-based compound may be 1:0.3 to 1:0.7. In addition, the weight ratio of the diisocyanate-based compound and the hydroxyl group-containing (meth)acrylate-based compound may be 1:0.1 to 1:0.5. When the molar ratio and / or weight ratio of the diisocyanate-based compound and the hydroxyl group-containing (meth)acrylate-based compound are within the above-mentioned range, the urethane bond between the diisocyanate-based compound and the hydroxyl group-containing (meth)acrylate-based compound can be stably performed, and an appropriate level of average urethane bond number can be formed in the urethane (meth)acrylate-based oligomer.

[0057] According to one embodiment of the present invention, based on 100 parts by weight of the first monomer mixture, the content of the diisocyanate-based compound may be 5 parts by weight or more and 20 parts by weight or less, 5 parts by weight or more and 15 parts by weight or less, 5 parts by weight or more and 10 parts by weight or less, 7.5 parts by weight or more and 15 parts by weight or less, or 10 parts by weight or more and 20 parts by weight or less. When the content of the diisocyanate-based compound is within the above-mentioned range, the urethane bond between the diisocyanate-based compound and the polydiol-based compound can be stably performed, and an appropriate level of average urethane bond number can be formed in the urethane (meth)acrylate-based oligomer.

[0058] According to one embodiment of the present invention, based on 100 parts by weight of the first monomer mixture, the content of the polydiol-based compound may be 89 parts by weight or more and 95 parts by weight or less, or 90 parts by weight or more and 95 parts by weight or less. When the content of the polydiol-based compound is within the above-mentioned range, the urethane bond between the diisocyanate-based compound and the polydiol-based compound can be stably performed, and an appropriate level of average urethane bond number can be formed in the urethane (meth)acrylate-based oligomer. In addition, the photocurable composition can implement excellent mechanical properties and foldability under high temperature and high humidity conditions after curing, and can have excellent surface printing characteristics.

[0059] According to one embodiment of the present invention, based on 100 parts by weight of the first monomer mixture, the content of the hydroxyl group-containing (meth)acrylate-based compound may be 0.5 parts by weight or more and 2 parts by weight or less, 1 part by weight or more and 2 parts by weight or less, or 1.5 parts by weight or more and 2 parts by weight or less. When the content of the hydroxyl group-containing (meth)acrylate-based compound is within the above-mentioned range, the urethane bond between the diisocyanate-based compound and the hydroxyl group-containing (meth)acrylate-based compound can be stably performed, and the (meth)acrylate group can be stably capped at the terminal of the urethane (meth)acrylate-based oligomer. In addition, the photocurable composition can implement excellent mechanical properties and foldability under high temperature and high humidity conditions after curing, and can have excellent surface printing characteristics.

[0060] According to one embodiment of the present invention, the first monomer mixture may include a polyol compound other than a polydiol compound containing a double bond. For example, depending on the intended use and required physical properties of the cured product of the photocurable composition, the first monomer mixture may include a polydiol compound containing a double bond within a repeating unit outside the range of the above-described number average molecular weight, a polydiol compound not containing a double bond within a repeating unit, a polyol compound containing three or more hydroxyl groups, etc.

[0061] According to one embodiment of the present invention, the oligomer syrup may include a urethane (meth)acrylate oligomer and a reactive diluting monomer. The reactive diluting monomer may control reactivity by adjusting the viscosity of the oligomer syrup, and may react with reactive monomers included in a photocurable composition described below to improve the mechanical properties of a cured product of the photocurable composition.

[0062] According to one embodiment of the present invention, the reactive dilution monomer is bornyl (meth)acrylate, isobornyl (meth)acrylate, tricyclotecanyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentadiene (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, methoxyethylene glycol (meth)acrylate, polypropylene glycol mono (meth)acrylate, polyethylene glycol mono (meth)acrylate, phenoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, epoxydiethylene glycol (meth)acrylate, butoxyethyl (meth)acrylate, styryl (meth)acrylate, Octadecyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, undecyl (meth)acrylate, isodecyl (meth)acrylate, decyl (meth)acrylate, nonyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, octyl (meth)acrylate, heptyl (meth)acrylate, hexyl (meth)acrylate, isoamyl (meth)acrylate, pentyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, amyl (meth)acrylate, butyl (meth)acrylate, isopropyl (meth)acrylate, propyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, It may include at least one of 7-amino-3,7-dimethyloctyl(meth)acrylate and N,N'-dimethyl-aminopropyl(meth)acrylate.

[0063] Specifically, the reactive diluting monomer may include at least a (meth)acrylate-based compound containing a cycloalkyl group having 5 to 10 carbon atoms. The (meth)acrylate-based compound containing a cycloalkyl group having 5 to 10 carbon atoms has excellent stability at high temperatures, and may react with reactive monomers included in the photocurable composition while controlling the viscosity of the oligomer syrup, thereby improving the mechanical properties of a cured product of the photocurable composition. The reactive diluting monomer may include at least one of isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, and trimethylcyclohexyl (meth)acrylate.

[0064] According to one embodiment of the present invention, the content of the reactive dilution monomer may be 25 parts by weight or more and 50 parts by weight or less, 25 parts by weight or more and 40 parts by weight or less, or 25 parts by weight or more and 35 parts by weight or less, based on 100 parts by weight of the oligomer syrup. When the content of the reactive dilution monomer is within the above-mentioned range, the viscosity of the oligomer syrup may be adjusted to an appropriate range, so that the reactivity may be excellent, and the mechanical properties of the cured product of the photocurable composition may be improved by reacting with other reactive monomers included in the photocurable composition.

[0065] According to one embodiment of the present invention, the viscosity of the oligomer syrup may be 70,000 cps or more and 100,000 cps or less at 25°C, and 10,000 cps or more and 18,000 cps or less at 60°C. When the viscosity of the oligomer syrup is within the above-described range, the processability of the oligomer syrup is excellent, and it can be easily mixed with the second monomer mixture described below.

[0066]

[0067] According to one embodiment of the present invention, the second monomer mixture may include a (meth)acrylamide-based first monomer. Specifically, the first monomer is (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, Nn-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-ethylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide N-butoxymethyl(meth)acrylamide, It may include at least one of isobutoxymethyl(meth)acrylamide and diacetone(meth)acrylamide. By including the first monomer of the aforementioned type, the cured product of the photocurable composition may have excellent impact resistance and foldability.

[0068] According to one embodiment of the present invention, the content of the first monomer may be 10 parts by weight or more and 30 parts by weight or less, 10 parts by weight or more and 20 parts by weight or less, or 15 parts by weight or more and 30 parts by weight or less, based on 100 parts by weight of the oligomer syrup. In addition, the content of the first monomer may be 5 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the photocurable composition. When the content of the first monomer is within the above-mentioned range, the photocurable composition can provide a cured product having excellent impact resistance and foldability.

[0069] According to one embodiment of the present invention, the second monomer mixture may include a pyrrolidone-based second monomer. Specifically, the second monomer may include at least one of N-vinylpyrrolidone, N-methyl-2-pyrrolidone, 2-pyrrolidone, and N-ethylpyrrolidone. By including the aforementioned type of second monomer, the cured product of the photocurable composition may have excellent impact resistance and foldability.

[0070] According to one embodiment of the present invention, the content of the second monomer may be 15 parts by weight or more and 35 parts by weight or less, 20 parts by weight or more and 30 parts by weight or less, or 15 parts by weight or more and 25 parts by weight or less, based on 100 parts by weight of the oligomer syrup. In addition, the content of the second monomer may be 5 parts by weight or more and 20 parts by weight or less, or 10 parts by weight or more and 15 parts by weight or less, based on 100 parts by weight of the photocurable composition. When the content of the second monomer is within the above-mentioned range, the photocurable composition can provide a cured product having excellent impact resistance and foldability.

[0071] According to one embodiment of the present invention, the second monomer mixture may include a third monomer containing a nitrogen- and oxygen-containing heterocyclic group having 3 to 8 carbon atoms. Specifically, the third monomer may include a hexagonal heterocyclic group containing nitrogen and oxygen. The third monomer may include at least (meth)acryloyl morpholine. By including the third monomer of the aforementioned type, the cured product of the photocurable composition may have excellent impact resistance and foldability.

[0072] According to one embodiment of the present invention, the content of the third monomer may be 10 parts by weight or more and 30 parts by weight or less, 10 parts by weight or more and 20 parts by weight or less, or 10 parts by weight or more and 15 parts by weight or less, based on 100 parts by weight of the oligomer syrup. In addition, the content of the third monomer may be 5 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the photocurable composition. When the content of the third monomer is within the above-mentioned range, the photocurable composition can provide a cured product having excellent impact resistance and foldability.

[0073] According to one embodiment of the present invention, the second monomer mixture may include a fourth monomer containing a cycloalkyl group having 5 to 10 carbon atoms. Specifically, the fourth monomer may include at least one of isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, and trimethylcyclohexyl (meth)acrylate. By including the fourth monomer of the aforementioned type, the cured product of the photocurable composition may have excellent impact resistance and foldability.

[0074] According to one embodiment of the present invention, the content of the fourth monomer may be 5 parts by weight or more and 15 parts by weight or less, or 7.5 parts by weight or more and 12.5 parts by weight or less, based on 100 parts by weight of the oligomer syrup. In addition, the content of the fourth monomer may be 3 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the photocurable composition. When the content of the fourth monomer is within the above-mentioned range, the photocurable composition can provide a cured product having excellent impact resistance and foldability.

[0075] According to one embodiment of the present invention, the second monomer mixture may include a fifth monomer of the (meth)acrylate type containing an oxygen-containing heterocyclic group having 4 to 9 carbon atoms. Specifically, the fifth monomer may include a hexagonal heterocyclic group containing oxygen. The fifth monomer may include at least one of tetrahydrofurfuryl (meth)acrylate and cyclic trimethylolpropane formal (meth)acrylate. By including the fifth monomer of the aforementioned type, the cured product of the photocurable composition may have excellent impact resistance and foldability.

[0076] According to one embodiment of the present invention, the content of the fifth monomer may be 5 parts by weight or more and 15 parts by weight or less, or 5 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the oligomer syrup. In addition, the content of the fifth monomer may be 3 parts by weight or more and 10 parts by weight or less, based on 100 parts by weight of the photocurable composition. When the content of the fifth monomer is within the above-mentioned range, the photocurable composition can provide a cured product having excellent impact resistance and foldability.

[0077] According to one embodiment of the present invention, the second monomer mixture may include two (meth)acrylate group-containing sixth monomers. Specifically, the sixth monomer may include at least one of hexanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, tris(2-hydroxyethyl)isocyanurate di(meth)acrylate, and tricyclodecane dimethanol di(meth)acrylate. By including the sixth monomer of the aforementioned type, the cured product of the photocurable composition may have excellent impact resistance and foldability.

[0078] According to one embodiment of the present invention, the content of the sixth monomer may be 15 parts by weight or more and 35 parts by weight or less, 20 parts by weight or more and 30 parts by weight or less, or 15 parts by weight or more and 25 parts by weight or less, based on 100 parts by weight of the oligomer syrup. In addition, the content of the sixth monomer may be 10 parts by weight or more and 20 parts by weight or less, based on 100 parts by weight of the photocurable composition. When the content of the sixth monomer is within the above-mentioned range, the photocurable composition can provide a cured product having excellent impact resistance and foldability.

[0079] According to one embodiment of the present invention, the second monomer mixture may include a seventh monomer containing three or more (meth)acrylate groups. Specifically, the seventh monomer may contain three or more and eight or less (meth)acrylate groups.

[0080] The seventh monomer may include at least one of pentaerythritol tri(meth)acrylate, propane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxy tri(meth)acrylate, glycerin propoxylated tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. By including the seventh monomer of the aforementioned type, the cured product of the photocurable composition may have excellent impact resistance and foldability.

[0081] According to one embodiment of the present invention, the content of the seventh monomer may be 1 part by weight or more and 10 parts by weight or less, 3 parts by weight or more and 7 parts by weight or less, or 1 part by weight or more and 5 parts by weight or less, based on 100 parts by weight of the oligomer syrup. In addition, the content of the seventh monomer may be 1 part by weight or more and 5 parts by weight or less, based on 100 parts by weight of the photocurable composition. When the content of the seventh monomer is within the above-mentioned range, the photocurable composition can provide a cured product having excellent impact resistance and foldability.

[0082] According to one embodiment of the present invention, the weight ratio of the third monomer to the fifth monomer may be 1:0.3 to 1:0.8, or 1:0.4 to 1:0.6. When the weight ratio of the third monomer containing an oxygen-containing ring group to the fifth monomer is within the above-mentioned range, the cured product of the photocurable composition may have excellent impact resistance and foldability, and may have excellent surface printing characteristics. Specifically, the cured product of the photocurable composition may not cause cracks, lifting, wrinkles, etc. even when deformed by folding, rolling, etc., and may have excellent impact resistance to external impact.

[0083] According to one embodiment of the present invention, the weight ratio of the sixth monomer to the seventh monomer may be 1:0.05 to 1:0.3, or 1:0.1 to 1:0.2. When the weight ratio of the sixth monomer and the seventh monomer containing multiple (meth)acrylate groups is within the above-mentioned range, the cured product of the photocurable composition may have excellent impact resistance and folding properties, and may have excellent surface printing characteristics. Specifically, the cured product of the photocurable composition may not cause cracks, lifting, wrinkles, etc. even when deformed by folding, rolling, etc., and may have excellent impact resistance to external impact.

[0084] According to one embodiment of the present invention, the photoinitiator may be a photoinitiator used in the art. For example, the photoinitiator may be 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenyl-acetophenone, 3-methylacetophenone, 1-(4-isopropyl-phenol)-2-hydroxy-2-methylpropan-1-one, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]butan-1-one, benzophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, benzaldehyde, anthraquinone, benzoinpropyl It may contain at least one of ether, benzoin ethyl ether, xanthon, and thioxanthon.

[0085] According to one embodiment of the present invention, the photoinitiator may include a ketone-based first photoinitiator and a phosphine oxide-based second photoinitiator. Specifically, the first photoinitiator may include at least one of 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenyl-acetophenone, 3-methylacetophenone, 1-(4-isopropyl-phenol)-2-hydroxy-2-methylpropan-1-one, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]butan-1-one, benzophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, and 4,4'-diaminobenzophenone. The second photoinitiator may include at least one of 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide, and phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide. By using the ketone-based first photoinitiator and the phosphine oxide-based second photoinitiator together, the photocuring efficiency of the photocurable composition can be further improved.

[0086] According to one embodiment of the present invention, the weight ratio of the first photoinitiator and the second photoinitiator may be 1:0.2 to 1:0.6. When the weight ratio of the first photoinitiator and the second photoinitiator is within the above-mentioned range, the photocurable composition can be stably photocured, and the photocuring efficiency can be further improved.

[0087] According to one embodiment of the present invention, the cured product of the photocurable composition may have a storage modulus of 2,500 MPa or more and 3,500 MPa or less at -20°C. In addition, the cured product of the photocurable composition may have a storage modulus of 2,800 MPa or more and 3,200 MPa or less at 25°C. In addition, the cured product of the photocurable composition may have a storage modulus of 2,000 MPa or more and 3,000 MPa or less at 60°C. The cured product of the photocurable composition may have excellent mechanical properties and foldability at low and high temperatures by satisfying the above-described ranges of storage moduli at low and high temperatures.

[0088]

[0089] One embodiment of the present invention provides a protective film including a cured product of the photocurable composition.

[0090] A protective film according to one embodiment of the present invention has the advantages of excellent impact resistance and folding properties, and easy printing on the surface.

[0091] According to one embodiment of the present invention, the protective film may include a protective layer comprising a cured product of the photocurable composition. Specifically, the protective layer may include a photocurable product of the photocurable composition. By including the protective layer, the protective film may exhibit excellent impact resistance and foldability.

[0092] According to one embodiment of the present invention, a UV lamp having a wavelength value of 250 nm or more and 450 nm or less is used, and 1.000 mJ / cm 2 5,000 mJ / cm2 The photocurable composition can be cured by irradiating it with light of .

[0093] According to one embodiment of the present invention, the thickness of the protective layer may be 10 μm or more and 100 μm or less. When the thickness of the protective layer is within the above-mentioned range, the protective film may have excellent impact resistance and foldability.

[0094] According to one embodiment of the present invention, the protective film may be a protective film for a display device. Specifically, the protective film may be a protective film for an OLED display device. In addition, the protective film may be a protective film for a flexible display device, a protective film for a foldable display device, or a protective film for a rollable display device. In other words, the protective film may be a protective film for a changeable display device.

[0095] According to one embodiment of the present invention, the protective film may be provided at various locations in the display device. For example, the protective film may be provided on the outer surface of the ultra-thin glass (UTG) of the display device. Specifically, the protective film may be provided on the opposite side of a light-emitting diode panel (e.g., an OLED panel) provided in the display device. In addition, the protective film may be provided between the UTG of the display device and the light-emitting diode panel (e.g., an OLED panel). That is, the protective film may be provided inside the display device.

[0096]

[0097] Hereinafter, the present invention will be described in detail using examples. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention is not limited to the examples described below. The examples in this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0098]

[0099] Example

[0100] Synthesis of urethane (meth)acrylate oligomers

[0101] To synthesize a urethane (meth)acrylate oligomer, the following materials were prepared.

[0102] Diisocyanate compound: isophorone diisocyanate

[0103] Polydiol compounds containing double bonds in the repeating unit: polybutadienediol, polyisoprenediol

[0104] Polydiol compound containing no double bonds in the repeating unit: polytetramethylene glycol

[0105] Hydroxy group-containing (meth)acrylate compound: 2-hydroxyethyl acrylate

[0106] Reactive dilution monomer: isobornyl acrylate

[0107]

[0108] Manufacturing Example 1

[0109] In a 2-liter round-bottom flask equipped with a stirrer, 111.0 g (0.5 mol) of isophorone diisocyanate and 0.13 g of dibutyltindilaurate as a catalyst were added. After maintaining the reaction temperature at 70°C, 1200.0 g (0.4 mol) of polybutadiene diol having a number-average molecular weight of 3000 g / mol was added to the reactor for 2 hours. After completion of the addition, the reaction was continued until the NCO concentration of the reactant reached the theoretical NCO concentration to obtain a urethane prepolymer, and the reaction temperature was lowered to 50°C, and 0.06 g of methylhydroquinone was added as a polymerization inhibitor. Next, since the reaction rate may slow down due to an increase in viscosity, 571.8 g of isobornyl acrylate was added to increase the stirring effect, and 23.2 g (0.2 mol) of 2-hydroxyethyl acrylate was slowly added to proceed with the reaction.

[0110] After the addition, the reaction temperature was maintained at 70°C for 2 hours, and the reaction was continued until the NCO concentration of the reactant disappeared, thereby synthesizing a urethane acrylate oligomer containing acrylate functional groups at both ends of the oligomer. The completion of the reaction was confirmed by infrared spectroscopy at 2270 cm -1 After confirming that the NCO peak disappeared, the weight-average molecular weight and number-average molecular weight of the oligomer were measured using gel permeation chromatography (GPC). The weight-average molecular weight was confirmed to be 44,842 g / mol, and the number-average molecular weight was confirmed to be 12,932 g / mol.

[0111] The viscosity of the oligomer syrup was 92,000 cps at 25°C and 12,000 cps at 60°C. Thus, it was found that a urethane (meth)acrylate oligomer having an average urethane bond number of 5 depending on the input ratio was synthesized. At this time, the content of isobornyl acrylate was approximately 30 parts by weight based on 100 parts by weight of the oligomer syrup.

[0112]

[0113] Manufacturing Example 2

[0114] In a 2-liter round-bottom flask equipped with a stirrer, 111.0 g (0.5 mol) of isophorone diisocyanate and 0.13 g of dibutyltin dilaurate as a catalyst were added. After maintaining the reaction temperature at 70°C, 1200.0 g (0.4 mol) of polyisoprenediol having a number-average molecular weight of 3000 g / mol was added to the reactor for 2 hours. After completion of the addition, the reaction was continued until the NCO concentration of the reactant reached the theoretical NCO concentration to obtain a urethane prepolymer, and the reaction temperature was lowered to 50°C, and 0.06 g of methylhydroquinone was added as a polymerization inhibitor. Next, since the reaction rate may slow down due to an increase in viscosity, 571.8 g of isobornyl acrylate was added to increase the stirring effect, and 23.2 g (0.2 mol) of 2-hydroxyethyl acrylate was slowly added to proceed with the reaction.

[0115] After the addition, the reaction temperature was maintained at 70°C for 2 hours, and the reaction was continued until the NCO concentration of the reactant disappeared, thereby synthesizing a urethane acrylate oligomer containing acrylate functional groups at both ends of the oligomer. The completion of the reaction was confirmed by infrared spectroscopy at 2270 cm -1 After confirming that the NCO peak disappeared, the weight-average molecular weight and number-average molecular weight of the oligomer were measured using gel permeation chromatography (GPC). The weight-average molecular weight was confirmed to be 46,036 g / mol, and the number-average molecular weight was confirmed to be 12,897 g / mol.

[0116] The viscosity of the oligomer syrup was 94,000 cps at 25°C and 15,000 cps at 60°C. Thus, it was found that a urethane (meth)acrylate oligomer having an average urethane bond number of 5 depending on the input ratio was synthesized. At this time, the content of isobornyl acrylate was approximately 30 parts by weight based on 100 parts by weight of the oligomer syrup.

[0117]

[0118] Manufacturing Example 3

[0119] In a 2-liter round-bottom flask equipped with a stirrer, 88.8 g (0.4 mol) of isophorone diisocyanate and 0.13 g of dibutyltin dilaurate as a catalyst were added. After maintaining the reaction temperature at 70°C, 1200.0 g (0.3 mol) of polybutadiene diol having a number-average molecular weight of 4000 g / mol was added to the reactor for 2 hours. After completion of the addition, the reaction was continued until the NCO concentration of the reactant reached the theoretical NCO concentration to obtain a urethane prepolymer, and the reaction temperature was lowered to 50°C, and 0.06 g of methylhydroquinone was added as a polymerization inhibitor. Next, since the reaction rate may slow down due to an increase in viscosity, 562.3 g of isobornyl acrylate was added to increase the stirring effect, and 23.2 g (0.2 mol) of 2-hydroxyethyl acrylate was slowly added to proceed with the reaction.

[0120] After the addition, the reaction temperature was maintained at 70°C for 2 hours, and the reaction was continued until the NCO concentration of the reactant disappeared, thereby synthesizing a urethane acrylate oligomer containing acrylate functional groups at both ends of the oligomer. The completion of the reaction was confirmed by infrared spectroscopy at 2270 cm -1 After confirming that the NCO peak disappeared, the weight-average molecular weight and number-average molecular weight of the oligomer were measured using gel permeation chromatography (GPC). The weight-average molecular weight was confirmed to be 44,962 g / mol, and the number-average molecular weight was confirmed to be 12,875 g / mol.

[0121] The viscosity of the oligomer syrup was 85,000 cps at 25°C and 12,000 cps at 60°C. Thus, it was found that a urethane (meth)acrylate oligomer having an average urethane bond number of 4 depending on the input ratio was synthesized. At this time, the content of isobornyl acrylate was approximately 30 parts by weight based on 100 parts by weight of the oligomer syrup.

[0122]

[0123] Comparative Manufacturing Example 1

[0124] In a 2-liter round-bottom flask equipped with a stirrer, 88.8 g (0.4 mol) of isophorone diisocyanate and 0.10 g of dibutyltin dilaurate as a catalyst were added. After maintaining the reaction temperature at 70°C, 900.0 g (0.3 mol) of polybutadiene diol having a number-average molecular weight of 3000 g / mol was added to the reactor for 2 hours. After completion of the addition, the reaction was continued until the NCO concentration of the reactant reached the theoretical NCO concentration to obtain a urethane prepolymer, and the reaction temperature was lowered to 50°C, and 0.05 g of methylhydroquinone was added as a polymerization inhibitor. Next, since the reaction rate may slow down due to an increase in viscosity, 433.7 g of isobornyl acrylate was added to increase the stirring effect, and 23.2 g (0.2 mol) of 2-hydroxyethyl acrylate was slowly added to proceed with the reaction.

[0125] After the addition, the reaction temperature was maintained at 70°C for 2 hours, and the reaction was continued until the NCO concentration of the reactant disappeared, thereby synthesizing a urethane acrylate oligomer containing acrylate functional groups at both ends of the oligomer. The completion of the reaction was confirmed by infrared spectroscopy at 2270 cm -1 After confirming that the NCO peak disappeared, the weight-average molecular weight and number-average molecular weight of the oligomer were measured using gel permeation chromatography (GPC). The weight-average molecular weight was confirmed to be 37,887 g / mol, and the number-average molecular weight was confirmed to be 10,063 g / mol.

[0126] The viscosity of the oligomer syrup was 59,000 cps at 25°C and 8,000 cps at 60°C. Thus, it was found that a urethane (meth)acrylate oligomer having an average urethane bond number of 4 depending on the input ratio was synthesized.

[0127]

[0128] Comparative Manufacturing Example 2

[0129] In a 2-liter round-bottom flask equipped with a stirrer, 111.0 g (0.5 mol) of isophorone diisocyanate and 0.13 g of dibutyltin dilaurate as a catalyst were added. After maintaining the reaction temperature at 70°C, 1200.0 g (0.4 mol) of polytetramethylene glycol having a number-average molecular weight of 3000 g / mol was added to the reactor for 2 hours. After completion of the addition, the reaction was continued until the NCO concentration of the reactant reached the theoretical NCO concentration to obtain a urethane prepolymer, and the reaction temperature was lowered to 50°C, and 0.06 g of methylhydroquinone was added as a polymerization inhibitor. Next, since the reaction rate may slow down due to an increase in viscosity, 571.8 g of isobornyl acrylate was added to increase the stirring effect, and 23.2 g (0.2 mol) of 2-hydroxyethyl acrylate was slowly added to proceed with the reaction.

[0130] After the addition, the reaction temperature was maintained at 70°C for 2 hours, and the reaction was continued until the NCO concentration of the reactant disappeared, thereby synthesizing a urethane acrylate oligomer containing acrylate functional groups at both ends of the oligomer. The completion of the reaction was confirmed by infrared spectroscopy at 2270 cm -1 After confirming that the NCO peak disappeared, the weight-average molecular weight and number-average molecular weight of the oligomer were measured using gel permeation chromatography (GPC). The weight-average molecular weight was confirmed to be 40,191 g / mol, and the number-average molecular weight was confirmed to be 12,116 g / mol.

[0131] The viscosity of the oligomer syrup was 71,000 cps at 25°C and 9,500 cps at 60°C. Thus, it was found that a urethane (meth)acrylate oligomer having an average urethane bond number of 5 depending on the input ratio was synthesized.

[0132]

[0133] Preparation of photocurable composition

[0134] To manufacture a photocurable composition, the following materials were prepared.

[0135] First monomer: N,N-dimethylacrylamide

[0136] Second monomer: N-vinylpyrrolidone

[0137] Third monomer: acryloyl morpholine

[0138] Fourth monomer: isobornyl acrylate

[0139] Fifth monomer: tetrahydrofurfuryl acrylate

[0140] 6th monomer: 1,6-hexanediol diacrylate

[0141] 7th monomer: pentaerythritol triacrylate

[0142] First photoinitiator: 1-hydroxycyclohexylphenyl ketone

[0143] Second photoinitiator: 2,4,6-trimethylbenzoyl diphenyl phosphine oxide

[0144]

[0145] Example 1

[0146] The prepared first to seventh monomers, first photoinitiator, and second photoinitiator were added to the oligomer syrup prepared in Manufacturing Example 1 in a reactor equipped with a stirrer. A photocurable composition was prepared by stirring at 400 rpm for 60 minutes at room temperature.

[0147] At this time, based on 100 parts by weight of the photocurable composition, the content of the oligomer syrup was 50 parts by weight, the content of the first monomer was 8 parts by weight, the content of the second monomer was 11 parts by weight, the content of the third monomer was 7 parts by weight, the content of the fourth monomer was 5 parts by weight, the content of the fifth monomer was 4 parts by weight, the content of the sixth monomer was 12 parts by weight, the content of the seventh monomer was 2 parts by weight, the content of the first photoinitiator was 0.7 parts by weight, and the content of the second photoinitiator was 0.3 parts by weight.

[0148]

[0149] Examples 2 to 5

[0150] In the above Example 1, a photocurable composition was manufactured in the same manner as in the above Example 1, except that the types and contents of the components included in the photocurable composition were adjusted as shown in Table 1 below.

[0151]

[0152] Example 1 Example 2 Example 3 Example 4 Example 5 Oligomer syrup Preparation Example 1; 50 parts by weight Preparation Example 2; 50 parts by weight Preparation Example 3; 50 parts by weight Preparation Example 1; 60 parts by weight Preparation Example 1; 60 parts by weight 1 Monomer 8 parts by weight 8 parts by weight 8 parts by weight 7 parts by weight 7 parts by weight 2 Monomer 11 parts by weight 11 parts by weight 11 parts by weight 9 parts by weight 9 parts by weight 3 Monomer 7 parts by weight 7 parts by weight 5 parts by weight 5 parts by weight 4 Monomer 5 parts by weight 5 parts by weight 4 parts by weight 4 parts by weight 5 Monomer 4 parts by weight 4 parts by weight 3 parts by weight 3 parts by weight 6 Monomer 12 parts by weight 12 parts by weight 10 parts by weight 10 parts by weight 7 Monomer 2 parts by weight 2 parts by weight 2 parts by weight 1 part by weight 1 Photoinitiator 0.7 parts by weight 0.7 parts by weight 0.7 parts by weight 0.7 parts by weight 2nd photoinitiator 0.3 parts by weight 0.3 parts by weight 0.3 parts by weight 0.3 parts by weight

[0153]

[0154] Comparative Examples 1 and 2

[0155] In the above Example 1, a photocurable composition was manufactured in the same manner as in the above Example 1, except that the types and contents of the components included in the photocurable composition were adjusted as shown in Table 2 below.

[0156]

[0157] Comparative Example 1 Comparative Example 2 Oligomer syrup Comparative Manufacturing Example 1; 50 parts by weight Comparative Manufacturing Example 2; 50 parts by weight 1 Monomer 8 parts by weight 8 parts by weight 2 Monomer 11 parts by weight 11 parts by weight 3 Monomer 7 parts by weight 7 parts by weight 4 Monomer 5 parts by weight 5 parts by weight 5 Monomer 4 parts by weight 4 parts by weight 6 Monomer 12 parts by weight 12 parts by weight 7 Monomer 2 parts by weight 2 parts by weight 1 Photoinitiator 0.7 parts by weight 0.7 parts by weight 2 Photoinitiator 0.3 parts by weight 0.3 parts by weight

[0158]

[0159] Manufacturing of protective layers

[0160] The photocurable compositions manufactured in the above examples and comparative examples were applied onto a PET substrate film or a release film using a slot die. Then, a metal halide UV lamp having a wavelength of 250 nm to 450 nm was used under nitrogen conditions, and the total light dose was 1.500 mJ / cm. 2 The photocurable composition was cured by irradiation.

[0161] Meanwhile, a photocurable composition is applied and laminated between the PET base film and the release film using a gap-roll coater, and a metal halide UV lamp having a wavelength of 250 nm or more and 450 nm or less is used to provide a total light dose of 1.500 mJ / cm. 2 The photocurable composition can also be cured by investigation.

[0162] The thickness of the protective layer was varied to meet the conditions required in the experimental examples described below.

[0163]

[0164] Experimental example

[0165] 1. Storage modulus evaluation

[0166] The storage modulus of the protective layer containing the photocurable composition was evaluated under the following conditions in accordance with ASTM D4065.

[0167] - Specimen (protective layer) thickness: 25 μm

[0168] - Measuring device: TA DAM Q800

[0169] - Measurement mode: Tension mode

[0170] - Temperature range: -20~60℃

[0171] - Heating rate: 5℃ / min

[0172] - Frequency: 1Hz

[0173] - Amplitude: 20 μm

[0174]

[0175] 2. Tensile strength / elongation / tensile modulus evaluation

[0176] The tensile strength, elongation, and tensile modulus of the protective layer containing the photocurable composition were evaluated under the following conditions.

[0177] - Specimen (protective layer) thickness: 25 μm

[0178] - Measuring device: UTM, KD Precision KDPI-130-2

[0179] - Measurement mode: Tensile mode

[0180] - Gauge length: 5cm

[0181] - Crosshead speed: 300mm / min

[0182] - Evaluation temperature: 25℃

[0183]

[0184] 3. Pendrop Test

[0185] The pen drop test of the protective layer containing the photocurable composition of the photocurable composition was evaluated under the following conditions.

[0186] - Preparation of specimen: Prepare a laminate having the following structure.

[0187] PET material protective film NRF (Net Replacement Film, 70 μm) / protective layer (25 μm) / OCA (35 μm) / UTG (38 μm) / PI (240 μm) / gravel plate

[0188] - Applicable pen: 0.3mm diameter

[0189] - Notation of measurement results: Increase the vertical drop height of the pen from the protective film surface in 5cm intervals, and indicate the height just before the specimen breaks as the result.

[0190]

[0191] 4. Evaluation of the number of room-temperature folding cycles

[0192] The room temperature folding test of the protective layer containing the photocurable composition was evaluated under the following conditions.

[0193] - Preparation of specimen: Prepare a laminate having the following structure.

[0194] Protective layer (25 μm) / OCA (35 μm) / UTG (38 μm)

[0195] - Folding conditions: 25 ℃, R=1.5

[0196] - Measurement result display: Displays the number of measurements in which cracks, lifting, and wrinkles occurred during repeated folding evaluation.

[0197]

[0198] 5. Evaluation of the number of low-temperature folding cycles

[0199] The low-temperature folding test of the protective layer containing the photocurable composition was evaluated under the following conditions.

[0200] - Preparation of specimen: Prepare a laminate having the following structure.

[0201] Protective layer (25 μm) / OCA (35 μm) / UTG (38 μm)

[0202] - Folding conditions: -20℃, R=1.5

[0203] - Measurement result display: Displays the number of measurements in which cracks, lifting, and wrinkles occurred during repeated folding evaluation.

[0204]

[0205] 6. Environmental reliability (high temperature, high humidity, thermal shock) evaluation

[0206] - Preparation of specimen: Prepare a laminate having the following structure.

[0207] Protective layer (25 μm) / OCA (35 μm) / UTG (38 μm)

[0208] - Evaluation conditions: 65℃ / 90%RH 240 hours (high temperature and high humidity), -40℃~85℃ (thermal shock), 100 cycles, stored in a folded state (R=1.5), and then observed with the naked eye.

[0209] - Measurement result notation: If there is no abnormality in appearance after observation, it is marked as 'pass'

[0210]

[0211] 7. Printability Evaluation

[0212] - Evaluation of printing on the protective layer surface

[0213] - Notation of measurement results: A printing layer was formed on the surface of the protective layer using a printing device, and the surface of the printing layer was attached and then removed using a high-adhesive tape. At this time, if there was no peeling on the surface of the printing layer and no damage, it was marked as ◎ (no defects), if there was no peeling on the surface of the printing layer but a small portion of the printing layer was transferred to the tape, it was marked as O, if there was slight peeling of the printing layer on the surface of the protective layer, it was marked as △, and if partial or complete peeling occurred, it was marked as X.

[0214]

[0215] Example 1 Example 2 Example 3 Example 4 Example 5 Storage modulus (MPa) -20℃ 3,1333,2953,3332,9842,87425℃ 2,9093,0053,0402,6042,51760℃ 2,6602,7612,7572,2692,264 Tensile strength (Mpa) 8.28.9 8.58.28.3 Elongation (%) 21.3 18.1 18.0 23.8 21.6 Tensile modulus (Mpa) 140.8 144.8 16 4.1 143.3 145.0 Pendrop test (cm) 25 25 25 30 30 Room temperature folding Number of times (times) > 200,000 > 200,000 > 200,000 > 200,000 -20℃ Number of times (times) > 100,000 > 100,000 > 100,000 > 100,000 Environmental reliability (high temperature and humidity, thermal shock) PassPassPassPassPassPrintabilityOO◎◎◎

[0216]

[0217] Comparative Example 1 Comparative Example 2 Storage modulus (MPa) -20℃ 2,2545,356 25℃ 1,9885,06460℃ 1,7584,710 Tensile strength (Mpa) 7.728.5 Elongation (%) 25.710.6 Tensile modulus (Mpa) 99.726 1.4 Pendrop test (cm) 2010 Number of folding times at room temperature 100,000 < 5,000 Number of folding times at -20℃ 50,000 < 5,000 Environmental reliability (high temperature and humidity, thermal shock) XX Printability △X

[0218]

[0219] Referring to Tables 3 and 4 above, it was confirmed that when the photocurable compositions of Examples 1 to 5 were used, the mechanical properties, impact resistance, folding properties, and printability were superior to those of Comparative Examples 1 and 2.

[0220] Therefore, it can be seen that the photocurable composition according to one embodiment of the present invention can provide a protective film having excellent impact resistance and folding properties and excellent surface printing properties.

Claims

1. An oligomer syrup comprising a urethane (meth)acrylate oligomer which is a reaction product of a first monomer mixture comprising a diisocyanate compound, a polydiol compound containing a double bond in a repeating unit, and a (meth)acrylate compound containing a hydroxy group; a second monomer mixture comprising one or more reactive monomers; and A photocurable composition comprising a photoinitiator.

2. In paragraph 1, The above urethane (meth)acrylate oligomer is, A photocurable composition which is a reaction product of a urethane prepolymer which is a reaction product of a mixture containing the diisocyanate compound and the polydiol compound and the hydroxyl group-containing (meth)acrylate compound.

3. In paragraph 1, A photocurable composition wherein the weight average molecular weight of the above urethane (meth)acrylate oligomer is 38,000 g / mol or more and the number average molecular weight is 10,500 g / mol or more.

4. In paragraph 1, A photocurable composition wherein the weight ratio of the diisocyanate compound and the polydiol compound is 1:10.5 to 1:

20.

5. In paragraph 1, The above second monomer mixture comprises a (meth)acrylamide-based first monomer, A photocurable composition in which the content of the first monomer is 10 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

6. In paragraph 1, The above second monomer mixture comprises a pyrrolidone-based second monomer, A photocurable composition in which the content of the second monomer is 15 parts by weight or more and 35 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

7. In paragraph 1, The second monomer mixture includes a third monomer containing a heterocyclic group having 3 to 8 carbon atoms and containing nitrogen and oxygen, A photocurable composition in which the content of the third monomer is 10 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

8. In paragraph 1, The second monomer mixture includes a fourth monomer containing a cycloalkyl group having 5 to 10 carbon atoms, A photocurable composition in which the content of the fourth monomer is 5 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

9. In paragraph 1, The second monomer mixture includes a fifth monomer of the (meth)acrylate type containing a heterocyclic group having 4 to 9 oxygen-containing carbon atoms, A photocurable composition in which the content of the fifth monomer is 5 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

10. In paragraph 1, The second monomer mixture comprises two (meth)acrylate group-containing sixth monomers, A photocurable composition in which the content of the sixth monomer is 15 parts by weight or more and 35 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

11. In paragraph 1, The second monomer mixture includes a seventh monomer containing three or more (meth)acrylate groups, A photocurable composition in which the content of the seventh monomer is 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

12. In paragraph 1, A photocurable composition in which the content of the photoinitiator is 1 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the oligomer syrup.

13. A protective film comprising a cured product of the photocurable composition according to Article 1.

14. In paragraph 13, The above protective film is a protective film for display devices.