Photocurable composition, adhesive, and display device

Abstract

The present invention relates to: a photocurable composition; an adhesive comprising same; and a display device comprising an adhesive layer comprising the photocurable composition. The photocurable composition can effectively increase the decap time of a nozzle by suppressing volatilization when applied to an inkjet process and realize excellent adhesive properties.

Description

Photocurable compositions, adhesives and display devices

[0001] The present invention relates to a photocurable composition, an adhesive, and a display device.

[0002]

[0003] Display devices have various components attached to the display panel, such as a polarizer, TPS, and cover window, as needed. When attaching these components, optical adhesives are used to minimize light loss and reflection.

[0004] Light has the property of being refracted or reflected when it encounters different layers of material. In display devices, light can also reflect and refraction when it encounters air (air caps inside the product, the atmosphere), glass, etc., which can reduce the display device's visibility. To minimize this problem, the air gap within the display product is filled with an optical adhesive that has similar optical properties before and after the light passes through it. Meanwhile, for use in display devices that express color and contrast, the optical adhesive must have high transparency to minimize changes in light, and the transparency at the time of bonding must remain unchanged over time.

[0005] Optical adhesives widely used in display devices can be divided into OCA (Optically Clear Adhesive), which is manufactured in the form of a film with an adhesive layer formed between double-sided release films, and OCR (Optically Clear Resin), which is supplied in a solution form and directly applied or injected.

[0006] OCR is a UV-curable adhesive used to enhance brightness. It is used in tablet PCs, smartphones, and touch panels to enhance light transmittance. By adjusting the refractive index, OCR can improve display visibility and reduce blur in bright environments. Furthermore, it offers the advantages of being less affected by large-area bonding and the characteristics of the bonding materials, and can simplify the process. However, it requires the development of a customized resin and process, and means to control shrinkage and overflow during curing. Furthermore, it can cause partial under-curing and staining.

[0007] Recently, inkjet printing technology using OCR solutions has been developed to replace the transparent adhesive film (OCA) used between the existing cover window and display panel. However, in the case of inkjet printing, there is a problem in that the ink head temperature is adjusted to eject high-viscosity materials via inkjet, which causes the chemical solution to evaporate, and the nozzle of the inkjet print head becomes clogged during the inkjet printing process, making it difficult to accurately form the desired pattern on the substrate for a long time. Consequently, a separate worker must replace the inkjet nozzle head and perform the printing process again, which is inconvenient, and the problem is that the process cost increases accordingly.

[0008]

[0009] The present invention provides a photocurable composition that can effectively increase the decap time of a nozzle by suppressing volatilization when applied to an inkjet process and can implement excellent adhesiveness, and a display device including an adhesive including the same and an adhesive layer including the photocurable composition.

[0010] 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.

[0011]

[0012] One embodiment of the present invention provides a photocurable composition comprising: a (meth)acrylate polymer; a (meth)acrylate monomer mixture; and a photoinitiator; wherein the (meth)acrylate monomer mixture includes at least two (meth)acrylate monomers having a vapor pressure of 0.001 mmHg or more and 0.1 mmHg or less.

[0013] According to one embodiment of the present invention, the (meth)acrylate polymer may include two or more (meth)acrylate functional groups.

[0014] According to one embodiment of the present invention, based on 100 parts by weight of the total of the (meth)acrylate polymer and the (meth)acrylate monomer mixture, the content of the (meth)acrylate polymer may be 10 parts by weight or more and 50 parts by weight or less.

[0015] According to one embodiment of the present invention, based on a total of 100 parts by weight of the (meth)acrylate polymer and (meth)acrylate monomer mixture, the content of the (meth)acrylate monomer mixture may be 60 parts by weight or more and 85 parts by weight or less.

[0016] According to one embodiment of the present invention, the (meth)acrylate monomer mixture may include a first (meth)acrylate monomer having a vapor pressure of 0.001 mmHg or more and 0.01 mmHg or less.

[0017]

[0018] According to one embodiment of the present invention, based on a total of 100 parts by weight of the (meth)acrylate polymer and (meth)acrylate monomer mixture, the content of the first (meth)acrylate monomer may be 20 parts by weight or more and 80 parts by weight or less.

[0019] According to one embodiment of the present invention, the (meth)acrylate monomer mixture may include a second (meth)acrylate monomer having a vapor pressure of more than 0.01 mmHg and less than or equal to 0.1 mmHg.

[0020] According to one embodiment of the present invention, based on a total of 100 parts by weight of the (meth)acrylate polymer and (meth)acrylate monomer mixture, the content of the second (meth)acrylate monomer may be 30 parts by weight or more and 60 parts by weight or less.

[0021] According to one embodiment of the present invention, the (meth)acrylate monomer mixture may have a content ratio of the first (meth)acrylate monomer and the second (meth)acrylate monomer of 1:1.1 to 1:2.5.

[0022] According to one embodiment of the present invention, the (meth)acrylate monomer mixture may have a content ratio of the first (meth)acrylate monomer and the second (meth)acrylate monomer of 1:1.4 to 1:2.4.

[0023] According to one embodiment of the present invention, the content of the photoinitiator may be 0.1 parts by weight or more and 5 parts by weight or less, based on 100 parts by weight of the total mixture of the (meth)acrylate polymer and the (meth)acrylate monomer.

[0024] According to one embodiment of the present invention, the viscosity of the photocurable composition may be 10 cp or more and 45 cp or less.

[0025] According to one embodiment of the present invention, the photocurable composition can satisfy the following mathematical formula 1.

[0026] [Mathematical Formula 1]

[0027] 0.02 ≤ B / A < 0.1

[0028] In the above mathematical expression 1, A is the weight of the photocurable composition sample before heating, and B is the weight of the photocurable composition sample volatilized after heating at 55°C for 30 minutes at a heating rate of 5°C / min.

[0029] According to one embodiment of the present invention, the photocurable composition can satisfy the following mathematical formula 2.

[0030] [Equation 2]

[0031] 0.039 ≤ B / A < 0.05

[0032] In the above mathematical expression 2, A is the weight of the photocurable composition sample before heating, and B is the weight of the photocurable composition sample volatilized after heating at 55°C for 30 minutes at a heating rate of 5°C / min.

[0033] One embodiment of the present invention provides an adhesive comprising the photocurable composition.

[0034] One embodiment of the present invention provides a display device including an adhesive layer including the photocurable composition.

[0035]

[0036] A photocurable composition according to one embodiment of the present invention can effectively increase the decap time of a nozzle by suppressing volatilization when applied to an inkjet process.

[0037] A photocurable composition according to one embodiment of the present invention can implement excellent adhesiveness after photocuring and have excellent adhesive stability.

[0038] An adhesive according to one embodiment of the present invention can have excellent adhesiveness and adhesive stability by including the photocurable composition.

[0039] A display device according to one embodiment of the present invention has the advantage of being able to display images of excellent quality and being able to be manufactured at reduced time and cost by including an adhesive layer formed using the photocurable composition.

[0040] The effects of the present invention are not limited to the effects described above, and effects not mentioned will be clearly understood by those skilled in the art from the present specification and the attached drawings.

[0041]

[0042] FIG. 1 is a photograph showing a state in which ink is ejected without clogging of the nozzle and a state in which clogging of the nozzle occurs in a decap time measurement, which is an experimental example according to one embodiment of the present invention. FIG. 1 (a) is a photograph showing a pattern formed by ejecting ink without clogging of the nozzle, and FIG. 1 (b) is a photograph showing a pattern formed by ejecting ink with clogging of the nozzle.

[0043]

[0044] 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.

[0045] 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.

[0046] Throughout this specification, the unit “parts by weight” may mean the weight ratio between each component.

[0047] Throughout this specification, terms containing 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.

[0048] Throughout this specification, “(meth)acrylate” is used to refer to both acrylate and methacrylate.

[0049] Throughout this specification, the viscosity of the compound may be a value measured using a Brookfield viscometer at a temperature of 25°C.

[0050]

[0051] Hereinafter, the present specification will be described in more detail.

[0052] One embodiment of the present invention provides a photocurable composition comprising: a (meth)acrylate polymer; a (meth)acrylate monomer mixture; and a photoinitiator; wherein the (meth)acrylate monomer mixture includes at least two (meth)acrylate monomers having a vapor pressure of 0.001 mmHg or more and 0.1 mmHg or less.

[0053] A photocurable composition according to one embodiment of the present invention can effectively increase the nozzle decap time by suppressing volatilization when applied to an inkjet printing process. In addition, the photocurable composition can implement excellent adhesiveness after photocuring and can have excellent adhesive stability. Specifically, the photocurable composition includes a (meth)acrylate monomer having a vapor pressure within a specific range, thereby exhibiting excellent thermal stability and implementing an increased nozzle decap time when applied to an inkjet printing process.

[0054] According to one embodiment of the present invention, the (meth)acrylate polymer may include two or more (meth)acrylate functional groups. Specifically, the (meth)acrylate polymer may include two or more methacrylate groups or acrylate groups bonded to the main chain. Since the (meth)acrylate polymer includes two or more (meth)acrylate functional groups, the photocurable composition capable of implementing excellent adhesive strength and adhesive stability after photocuring can be provided.

[0055] According to one embodiment of the present invention, the (meth)acrylate-based polymer may include at least one of an ether (meth)acrylate-based resin, a urethane (meth)acrylate-based resin, an epoxy (meth)acrylate-based resin, and an amide (meth)acrylate-based resin. The photocurable composition including the above-described type of (meth)acrylate-based polymer may have excellent adhesive strength and adhesive stability after photocuring.

[0056] According to one embodiment of the present invention, based on 100 parts by weight of the total of the (meth)acrylate-based polymer and the (meth)acrylate-based monomer mixture, the content of the (meth)acrylate-based polymer may be 10 parts by weight or more and 50 parts by weight or less. Specifically, based on 100 parts by weight of the combined weight of the (meth)acrylate-based polymer and the (meth)acrylate-based monomer mixture, the content of the (meth)acrylate-based polymer may be 15 parts by weight or more and 45 parts by weight or less, 20 parts by weight or more and 40 parts by weight or less, 25 parts by weight or more and 35 parts by weight or less, 10 parts by weight or more and 35 parts by weight or less, 15 parts by weight or more and 30 parts by weight or less, 20 parts by weight or more and 30 parts by weight or less, 20 parts by weight or more and 50 parts by weight or less, 25 parts by weight or more and 45 parts by weight or less, or 35 parts by weight or more and 40 parts by weight or less. By adjusting the content of the (meth)acrylate polymer contained in the photocurable composition within the aforementioned range, a photocurable composition capable of realizing excellent adhesive strength and adhesive stability after photocuring can be provided. In addition, when the content of the (meth)acrylate polymer is within the aforementioned range, the photocurable composition can have an appropriate viscosity, thereby having the advantage of facilitating inkjet processing.

[0057] According to one embodiment of the present invention, the photocurable composition may include two or more (meth)acrylate polymers. For example, the photocurable composition may include a first (meth)acrylate polymer and a second (meth)acrylate polymer. The first (meth)acrylate polymer and the second (meth)acrylate polymer may differ in the number of (meth)acrylate functional groups bonded to the main chain, the type of monomer for forming the main chain, the weight average molecular weight, etc.

[0058] The content ratio of the first (meth)acrylate-based polymer and the second (meth)acrylate-based polymer included in the photocurable composition may be 1:0.8 to 1:1.2. By adjusting the content ratio of the first (meth)acrylate-based polymer and the second (meth)acrylate-based polymer within the above-described range, the adhesive strength and adhesive stability after curing of the photocurable composition can be effectively improved.

[0059] According to one embodiment of the present invention, based on 100 parts by weight of the total of the (meth)acrylate-based polymer and the (meth)acrylate-based monomer mixture, the content of the (meth)acrylate-based monomer mixture may be 60 parts by weight or more and 85 parts by weight or less. Specifically, based on 100 parts by weight of the combined weight of the (meth)acrylate-based polymer and the (meth)acrylate-based monomer mixture, the content of the (meth)acrylate-based monomer mixture may be 62.5 parts by weight or more and 82.5 parts by weight or less, 65 parts by weight or more and 80 parts by weight or less, 62.5 parts by weight or more and 77.5 parts by weight or less, 60 parts by weight or more and 80 parts by weight or less and 70 parts by weight or more and 80 parts by weight or less, 75 parts by weight or more and 80 parts by weight or less, or 70 parts by weight or more and 85 parts by weight or less. When the content of the (meth)acrylate-based monomer mixture included in the photocurable composition is within the above-mentioned range, the photocurable composition can have improved thermal stability, and volatilization from the nozzle can be effectively suppressed when applied to an inkjet process. Accordingly, the photocurable composition can effectively increase the decap time of the nozzle in an inkjet printer. Here, the decap time of the nozzle can mean the time during which the solution can be sprayed without nozzle clogging when the inkjet printer is not in use. In addition, by adjusting the content of the (meth)acrylate-based monomer mixture within the above-mentioned range, the adhesive strength and adhesive stability of the photocurable composition after curing can be effectively improved. In addition, when the content of the (meth)acrylate-based monomer mixture is within the above-mentioned range, the photocurable composition can have an appropriate viscosity, and thus have excellent applicability and processability.

[0060] According to one embodiment of the present invention, the (meth)acrylate-based monomer mixture may include at least one of an alkyl group-containing (meth)acrylate, a cycloalkyl group-containing (meth)acrylate, an aromatic group-containing (meth)acrylate, a phenoxy group-containing (meth)acrylate, a hydroxy group-containing (meth)acrylate, an alkoxy group-containing (meth)acrylate, an ether group-containing (meth)acrylate, a heterocyclic (including element O)-containing (meth)acrylate, a halogen group-containing (meth)acrylate, and a siloxane group-containing (meth)acrylate.

[0061] For example, the above (meth)acrylate monomer mixture may be selected from the group consisting of methyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isoamyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, trimethoxybutyl (meth)acrylate, It may include at least one of ethoxy-diethylene glycol (meth)acrylate, methoxy-triethylene glycol (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, ethylcarbidol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-acryloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-fluoroethyl (meth)acrylate, 4-fluoropropyl (meth)acrylate, and triethylsiloxylethyl (meth)acrylate.

[0062] According to one embodiment of the present invention, the (meth)acrylate monomer mixture may include a first (meth)acrylate monomer having a vapor pressure of 0.001 mmHg or more and 0.01 mmHg or less. The vapor pressure of the first (meth)acrylate monomer may refer to a vapor pressure at 25°C. Specifically, the vapor pressure of the first (meth)acrylate monomer at 25°C may be 0.003 mmHg or more and 0.01 mmHg or less, 0.005 mmHg or more and 0.01 mmHg or less, or 0.007 mmHg or more and 0.01 mmHg or less. By using the first (meth)acrylate monomer having a vapor pressure range within the above-described range, the nozzle decap time of the photocurable composition can be effectively increased. In addition, the photocurable composition comprising the first (meth)acrylate monomer can have excellent adhesive strength and adhesive stability after photocuring.

[0063] According to one embodiment of the present invention, the first (meth)acrylate-based monomer may include a straight-chain or branched-chain (meth)acrylate containing an alkyl group having 10 to 20 carbon atoms. Specifically, the first (meth)acrylate-based monomer may include a straight-chain alkyl group having 10 to 18 carbon atoms, an alkyl group having 10 to 15 carbon atoms, or an alkyl group having 10 to 13 carbon atoms. For example, the first (meth)acrylate-based monomer may include at least one of isodecyl (meth)acrylate and lauryl (meth)acrylate. By using the above-described type of (meth)acrylate as the first (meth)acrylate-based monomer, the nozzle decap time of the photocurable composition can be effectively increased, and the adhesive strength and adhesive stability of the photocurable composition can be improved.

[0064] According to one embodiment of the present invention, based on a total of 100 parts by weight of the (meth)acrylate polymer and (meth)acrylate monomer mixture, the content of the first (meth)acrylate monomer may be 20 parts by weight or more and 80 parts by weight or less. Specifically, based on 100 parts by weight of the combined weight of the (meth)acrylate-based polymer and the (meth)acrylate-based monomer mixture, the content of the first (meth)acrylate-based monomer may be 25 parts by weight or more and 75 parts by weight or less, 30 parts by weight or more and 70 parts by weight or less, 35 parts by weight or more and 65 parts by weight or less, 40 parts by weight or more and 60 parts by weight or less, 45 parts by weight or more and 55 parts by weight or less, 20 parts by weight or more and 50 parts by weight or less, 22.5 parts by weight or more and 45 parts by weight or less, 25 parts by weight or more and 40 parts by weight or less, 20 parts by weight or more and 35 parts by weight or less, 50 parts by weight or more and 80 parts by weight or less, 55 parts by weight or more and 80 parts by weight or less, 60 parts by weight or more and 80 parts by weight or less, 65 parts by weight or more and 80 parts by weight or less, or 70 parts by weight or more and 80 parts by weight or less. By adjusting the content of the first (meth)acrylate monomer within the above-described range, the nozzle decap time of the photocurable composition can be effectively increased, and the adhesive strength and adhesive stability of the photocurable composition can be improved.

[0065] According to one embodiment of the present invention, the photocurable composition may include two or more first (meth)acrylate monomers. That is, the (meth)acrylate monomer mixture may include a first (meth)acrylate monomer and an additional first (meth)acrylate monomer. At this time, the content ratio of the first (meth)acrylate monomer and the additional first (meth)acrylate monomer may be 1:0.5 to 1:1.5. When the content ratio of the first (meth)acrylate monomer and the additional first (meth)acrylate monomer is within the above-mentioned range, the nozzle decap time of the photocurable composition may be increased.

[0066] According to one embodiment of the present invention, the (meth)acrylate monomer mixture may include a second (meth)acrylate monomer having a vapor pressure of more than 0.01 mmHg and less than or equal to 0.1 mmHg.

[0067] The vapor pressure of the second (meth)acrylate monomer may refer to the vapor pressure at 25°C. Specifically, the vapor pressure of the second (meth)acrylate monomer at 25°C may be more than 0.01 mmHg and less than or equal to 0.08 mmHg, more than 0.01 mmHg and less than or equal to 0.075 mmHg, more than 0.01 mmHg and less than or equal to 0.05 mmHg, or more than 0.01 mmHg and less than or equal to 0.035 mmHg. By using the second (meth)acrylate monomer having a vapor pressure range within the aforementioned range, the nozzle decap time of the photocurable composition can be effectively increased. In addition, the photocurable composition including the second (meth)acrylate monomer can have excellent adhesive strength and adhesive stability after photocuring.

[0068] According to one embodiment of the present invention, the first (meth)acrylate monomer may include at least one of a substituted or unsubstituted straight-chain or branched-chain alkyl group-containing (meth)acrylate having 1 to 9 carbon atoms, a substituted or unsubstituted cycloalkyl group-containing (meth)acrylate having 5 to 10 carbon atoms, and an aromatic group-containing (meth)acrylate. Specifically, in the substituted alkyl group-containing (meth)acrylate, the substituent may be a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms. In addition, in the substituted cycloalkyl group-containing (meth)acrylate, the substituent may include at least one straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, and two alkyl groups may be bonded to each other. The aromatic group-containing (meth)acrylate may include at least one of benzene and benzyl as the aromatic group. For example, the second (meth)acrylate monomer may include at least one of 2-propylheptyl (meth)acrylate, isobornyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, and benzyl (meth)acrylate. By using the above-described type of (meth)acrylate as the second (meth)acrylate monomer, the nozzle decap time of the photocurable composition can be effectively increased, and the adhesive strength and adhesive stability of the photocurable composition can be improved.

[0069] According to one embodiment of the present invention, based on 100 parts by weight of the total of the (meth)acrylate-based polymer and the (meth)acrylate-based monomer mixture, the content of the second (meth)acrylate-based monomer may be 30 parts by weight or more and 60 parts by weight or less. Specifically, based on 100 parts by weight of the combined weight of the (meth)acrylate-based polymer and the (meth)acrylate-based monomer mixture, the content of the second (meth)acrylate-based monomer may be 35 parts by weight or more and 55 parts by weight or less, 40 parts by weight or more and 50 parts by weight or less, 30 parts by weight or more and 50 parts by weight or less, 35 parts by weight or more and 45 parts by weight or less, 40 parts by weight or more and 45 parts by weight or less, 40 parts by weight or more and 60 parts by weight or less, 45 parts by weight or more and 60 parts by weight or less, or 50 parts by weight or more and 60 parts by weight or less. When the content of the second (meth)acrylate monomer is within the above-mentioned range, the nozzle decap time of the photocurable composition can be effectively increased, and the adhesive strength and adhesive stability of the photocurable composition can be improved.

[0070] According to one embodiment of the present invention, the (meth)acrylate monomer mixture may have a content ratio of the first (meth)acrylate monomer and the second (meth)acrylate monomer of 1:1.1 to 1:2.5. Specifically, the (meth)acrylate monomer mixture may include both the first (meth)acrylate monomer and the second (meth)acrylate monomer. At this time, the content ratio of the first (meth)acrylate monomer and the second (meth)acrylate monomer may be 1:1.3 to 1:2.2, 1:1.5 to 1:2.0, 1:1.1 to 1:1.8, 1:1.3 to 1:1.5, 1:1.8 to 1:2.5, or 1:2.0 to 1:2.3.

[0071] According to one embodiment of the present invention, the (meth)acrylate monomer mixture may have a content ratio of the first (meth)acrylate monomer and the second (meth)acrylate monomer of 1:1.4 to 1:2.4, 1:1.6 to 1:2.2, 1:1.8 to 1:2.0, 1:1.4 to 1:1.8, or 1:1.6 to 1:2.4.

[0072] When the content ratio of the first (meth)acrylate monomer and the second (meth)acrylate monomer included in the (meth)acrylate monomer mixture is within the above-mentioned range, the photocurable composition can have improved thermal stability, and volatilization from the nozzle can be effectively suppressed when applied to an inkjet process. In addition, the photocurable composition can have excellent adhesive strength and adhesive stability after photocuring.

[0073] According to one embodiment of the present invention, the photocurable composition may include a photoinitiator. Any photoinitiator used in the art may be used without limitation. Specifically, the photoinitiator may include at least one of an acetophenone-based compound, a benzophenone-based compound, a thioxanthone-based compound, a benzoin-based compound, and a triazine-based compound.For example, the photoinitiator is an acetophenone-based compound such as 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-hydroxy-2-methylpropiophenone, pt-butyltrichloroacetophenone, pt-butyldichloroacetophenone, benzophenone, 4-chloroacetophenone, 4,4'-dimethylaminobenzophenone, 4,4'-dichlorobenzophenone, 3,3'-dimethyl-2-methoxybenzophenone, 2,2'-dichloro-4-phenoxyacetophenone, 2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one; Benzophenone compounds such as benzophenone, benzoyl benzoate, methyl benzoyl benzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone; benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and benzyl dimethyl ketal; and 2,4,6,-trichloro s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(3',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4'-methoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tryl)-4,6-bis(trichloromethyl)-s-triazine, 2-phenyl 4,6-bis(trichloromethyl)-s-triazine, bis(trichloromethyl)-6-styryl s-triazine, 2-(naphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, It may include at least one of triazine compounds such as 2-(4-methoxynaphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-4-trichloromethyl(piperonyl)-6-triazine, and 2-4-trichloromethyl(4'-methoxystyryl)-6-triazine.

[0074] According to one embodiment of the present invention, the content of the photoinitiator may be 0.1 part by weight or more and 5 parts by weight or less, based on 100 parts by weight of the total of the (meth)acrylate-based polymer and (meth)acrylate-based monomer mixture. By adjusting the content of the photoinitiator within the above-mentioned range, stable photocuring of the photocurable composition can be achieved, and the curing speed can be improved. In addition, when the content of the photoinitiator is within the above-mentioned range, the optical properties of the photocurable composition, such as transmittance and yellow index, can be effectively prevented from being deteriorated.

[0075] According to one embodiment of the present invention, the photoinitiator may include two or more types of photoinitiators. For example, the photoinitiator may include a first photoinitiator and a second photoinitiator. When the photoinitiator includes a first photoinitiator and a second photoinitiator, the curing process of the photocurable composition can be effectively performed, and the degree of curing of the photocurable composition can be more easily controlled.

[0076] According to one embodiment of the present invention, the photocurable composition may further include an additive. Specifically, the additive may include at least one of a stabilizer, a tackifying resin, an epoxy resin, a crosslinking agent, an ultraviolet stabilizer, an antioxidant, a coloring agent, a reinforcing agent, a filler, an anti-foaming agent, a surfactant, and a plasticizer. The content of the additive may be adjusted within a range that does not affect the desired physical properties of the photocurable composition.

[0077] In order to ensure stability and reliability in various environments (e.g., high temperature, high temperature and high humidity, excessive ultraviolet rays, etc.) in which the photocurable composition is used, the photocurable composition may include a stabilizer as an additive. At this time, the content of the stabilizer may be 0.05 parts 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 stabilizer is within the above-mentioned range, yellowing in environments such as high temperature, high temperature and high humidity can be suppressed, and the optical properties of the photocurable composition can be prevented from deteriorating.

[0078] According to one embodiment of the present invention, the viscosity of the photocurable composition may be 10 cp or more and 45 cp or less. The viscosity of the photocurable composition may be measured using a Brookfield viscometer at a temperature of 25° C., a rotation speed of 150 rpm or more and 200 rpm or less, and a spindle of No. 40. The photocurable composition having a viscosity within the aforementioned range can be effectively discharged when applied to an inkjet printer, and can have excellent application properties and processability.

[0079] According to one embodiment of the present invention, the photocurable composition can satisfy the following mathematical formula 1.

[0080] [Mathematical Formula 1]

[0081] 0.02 ≤ B / A < 0.1

[0082] In the above mathematical expression 1, A is the weight of the photocurable composition sample before heating, and B is the weight of the photocurable composition sample volatilized after heating at 55°C for 30 minutes at a heating rate of 5°C / min.

[0083] That is, in the above mathematical formula 1, the percentage (%) for B / A may be 2% or more and less than 10%. Specifically, the percentage for B / A in the above mathematical formula 1 for the photocurable composition may be 2% or more and 9.9% or less, 3% or more and 9.5% or less, 4% or more and 8% or less, 5% or more and 6% or less, 2% or more and 6.5% or less, or 5% or more and less than 10%. The photocurable composition satisfying the above chemical formula 1 has excellent thermal stability, so that volatilization from the nozzle can be effectively suppressed when applied to an inkjet process. Through this, the photocurable composition can effectively increase the decap time of the nozzle in an inkjet printer.

[0084] According to one embodiment of the present invention, the photocurable composition can satisfy the following mathematical formula 2.

[0085] [Equation 2]

[0086] 0.039 ≤ B / A < 0.05

[0087] In the above mathematical expression 2, A is the weight of the photocurable composition sample before heating, and B is the weight of the photocurable composition sample volatilized after heating at 55°C for 30 minutes at a heating rate of 5°C / min.

[0088] That is, in the above mathematical formula 2, the percentage (%) for B / A may be 3.9% or more and less than 5%. Specifically, the percentage for B / A in the above mathematical formula 2 for the photocurable composition may be 4% or more and 4.9% or less, 4.3% or more and 4.8% or less, 3.9% or more and 4.6% or less, or 4.5% or more and less than 5%. The photocurable composition satisfying the above chemical formula 2 has improved thermal stability, so that volatilization from the nozzle can be more effectively suppressed when applied to an inkjet process. Through this, the photocurable composition can more effectively increase the decap time of the nozzle in an inkjet printer.

[0089]

[0090] One embodiment of the present invention provides an adhesive comprising the photocurable composition.

[0091] An adhesive according to one embodiment of the present invention can have excellent adhesiveness and adhesive stability by including the photocurable composition.

[0092] According to one embodiment of the present invention, the adhesive may include a photocurable product of the photocurable composition. At this time, in order to form the adhesive, first photocuring (pre-curing) and second photocuring (main curing) may be performed on the photocurable composition. For example, the photocurable composition may be applied on a first member, and the photocurable composition may be pre-cured by irradiating with ultraviolet rays, thereby forming a pre-cured adhesive film. Thereafter, a second member may be laminated on an exposed surface of the pre-cured adhesive film, thereby attaching the first member and the second member. That is, the first member, the pre-cured adhesive film, and the second member may have a structure in which they are sequentially laminated. Thereafter, the pre-cured adhesive film may be cured by irradiating with ultraviolet rays, thereby finally forming an adhesive.

[0093] At this time, the ultraviolet rays (first ultraviolet rays) irradiated for the first photocuring (temporary curing) of the photocurable composition and the ultraviolet rays (second ultraviolet rays) irradiated for the second photocuring (main curing) may be irradiated to the photocurable composition using different irradiation means. For example, the first ultraviolet rays may be irradiated using a 365 nm UV LED, and the second ultraviolet rays may be irradiated using a metal mercury lamp. Meanwhile, in order to control the curing rates of the temporary curing and main curing, the light quantity, intensity, etc. of the first ultraviolet rays and the second ultraviolet rays may be adjusted.

[0094]

[0095] One embodiment of the present invention provides a display device including an adhesive layer including the photocurable composition.

[0096] A display device according to one embodiment of the present invention has the advantage of being able to display images of excellent quality and being able to be manufactured at reduced time and cost by including an adhesive layer formed using the photocurable composition.

[0097] According to one embodiment of the present invention, the adhesive layer may include a photocurable product of the photocurable composition. At this time, in order to form the adhesive layer, first photocuring (pre-curing) and second photocuring (main curing) may be performed on the photocurable composition. For example, the photocurable composition may be applied on a first member, and the photocurable composition may be pre-cured by irradiating the member with ultraviolet rays, thereby forming a pre-cured adhesive film. Thereafter, a second member may be laminated on an exposed surface of the pre-cured adhesive film, thereby attaching the first member and the second member. That is, the first member, the pre-cured adhesive film, and the second member may have a structure in which they are sequentially laminated. Thereafter, the pre-cured adhesive film may be cured by irradiating the member with ultraviolet rays, thereby finally forming an adhesive layer.

[0098] The first member and the second member may be components included in the display device. For example, the first member may be a substrate of the display device, and the second member may be a light-transmitting cover. However, the types of members attached by the adhesive layer are not limited to those described above.

[0099] According to one embodiment of the present invention, the display device may include, without limitation, any display device used in the art. For example, the display device may be a display device such as an LCD or OLED, and may be a foldable display device, a flexible display device, or the like.

[0100]

[0101] 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.

[0102]

[0103] Example

[0104] CN9004 (Sartomer) and CN3100 (Sartomer), which are aliphatic urethane acrylate resins, were prepared as (meth)acrylate polymers.

[0105] As the first (meth)acrylate monomer, isodecyl acrylate (IDA; vapor pressure at 25°C: less than 0.01 mm Hg) and lauryl acrylate (LA; vapor pressure at 25°C: 0.01 mm Hg) were prepared.

[0106] In addition, as second (meth)acrylate monomers, 2-propylheptyl acrylate (2-PHA; vapor pressure at 25°C: 0.011 mm Hg), isobornyl acrylate (IBOA; vapor pressure at 25°C: 0.03 mm Hg), t-butylcyclohexyl acrylate (t-TBCA; vapor pressure at 25°C: 0.0131 mm Hg), and benzyl acrylate (BA; vapor pressure at 25°C: 0.073 mm Hg) were prepared.

[0107] Meanwhile, 2-ethylhexyl acrylate (2-EHA; vapor pressure at 25°C: 0.178 mm Hg) was prepared as a (meth)acrylate monomer having a vapor pressure exceeding 0.1 mmHg.

[0108] As photoinitiators, Igacure 651 (2,2-Dimethoxy-1,2-diphenylethan-1-one; BASF) and TPO (2,4,6-trimethylbenzoyldiphenyl phosphine oxide; BASF) were prepared.

[0109]

[0110] Example 1

[0111] A photocurable composition was prepared by mixing (meth)acrylate polymers CN9004 and CN3100, first (meth)acrylate monomers IDA and LA, and photoinitiators I651 and TPO.

[0112] At this time, based on a total of 100 parts by weight of the mixture of (meth)acrylate polymer and (meth)acrylate monomer, the content of CN3100 was 14 parts by weight, the content of CN9004 was 14 parts by weight, the content of IDA was 42 parts by weight, and the content of LA was 30 parts by weight. In addition, based on a total of 100 parts by weight of the mixture of (meth)acrylate polymer and (meth)acrylate monomer, the content of I651 was 1 part by weight, and the content of TPO was 1 part by weight.

[0113]

[0114] Example 2

[0115] A photocurable composition was prepared in the same manner as in Example 1, except that the contents of CN9004, CN3100, IDA, LA, I651, and TPO were adjusted as shown in Table 1 below.

[0116]

[0117] Example 3

[0118] A photocurable composition was prepared by mixing (meth)acrylate polymers CN9004 and CN3100, a first (meth)acrylate monomer IDA, a second (meth)acrylate monomer 2-PHA, and photoinitiators I651 and TPO.

[0119] At this time, based on a total of 100 parts by weight of the mixture of (meth)acrylate polymer and (meth)acrylate monomer, the content of CN3100 was 14 parts by weight, the content of CN9004 was 14 parts by weight, the content of IDA was 30 parts by weight, and the content of 2-PHA was 42 parts by weight. In addition, based on a total of 100 parts by weight of the mixture of (meth)acrylate polymer and (meth)acrylate monomer, the content of I651 was 1 part by weight, and the content of TPO was 1 part by weight.

[0120]

[0121] Examples 4 to 14

[0122] A photocurable composition was prepared in the same manner as in Example 3, except that the types and contents of the (meth)acrylate polymer, the first (meth)acrylate monomer, the second (meth)acrylate monomer, and the photoinitiator were adjusted, as shown in Tables 1 and 2 below.

[0123]

[0124] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 ACN31001414141311141311CN90041414141311141311BIDA4230302423---LA3042---3024232-PHA--425055425055CI65111111111TPO11111111

[0125] In the above Table 1, “A” is a (meth)acrylate polymer, “B” is a (meth)acrylate monomer mixture, and “C” is a photoinitiator. In the above Table 1, the contents (parts by weight) of CN3100, CN9004, IDA, LA, and 2-PHA are based on 100 parts by weight of the total of the (meth)acrylate polymer (A) and the (meth)acrylate monomer mixture (B). In addition, the contents (parts by weight) of I651 and TPO are based on 100 parts by weight of the total of the (meth)acrylate polymer (A) and the (meth)acrylate monomer mixture (B).

[0126] Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 ACN3100141414141414CN9004141414141414BIDA30-30-30-LA-30-30-30IBOA4242----t-TBCA--4242--BA----4242CI651111111TPO111111

[0127] In the above Table 2, “A” is a (meth)acrylate polymer, “B” is a (meth)acrylate monomer mixture, and “C” is a photoinitiator. In the above Table 2, the contents (parts by weight) of CN3100, CN9004, IDA, LA, IBOA, t-TBCA, and BA are based on 100 parts by weight of the total of the (meth)acrylate polymer (A) and the (meth)acrylate monomer mixture (B). In addition, the contents (parts by weight) of I651 and TPO are based on 100 parts by weight of the total of the (meth)acrylate polymer (A) and the (meth)acrylate monomer mixture (B).

[0128]

[0129] Comparative Example 1

[0130] A photocurable composition was prepared by mixing (meth)acrylate polymers CN9004 and CN3100, (meth)acrylate monomers IDA and 2-EHA, and photoinitiators I651 and TPO.

[0131] At this time, based on a total of 100 parts by weight of the mixture of (meth)acrylate polymer and (meth)acrylate monomer, the content of CN3100 was 14 parts by weight, the content of CN9004 was 14 parts by weight, the content of IDA was 30 parts by weight, and the content of 2-EHA was 42 parts by weight. In addition, based on a total of 100 parts by weight of the mixture of (meth)acrylate polymer and (meth)acrylate monomer, the content of I651 was 1 part by weight, and the content of TPO was 1 part by weight.

[0132]

[0133] Comparative Examples 2 to 4

[0134] As shown in Table 3 below, a photocurable composition was prepared in the same manner as in Comparative Example 1, except that the types and contents of the (meth)acrylate polymer, (meth)acrylate monomer, and photoinitiator were adjusted.

[0135]

[0136] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 ACN310014111411CN900414111411 BIDA3023--LA--30232-EHA42554255CI6511111TPO1111

[0137] In the above Table 3, “A” is a (meth)acrylate polymer, “B” is a (meth)acrylate monomer mixture, and “C” is a photoinitiator. In the above Table 3, the contents (parts by weight) of CN3100, CN9004, IDA, LA, and 2-EHA are based on 100 parts by weight of the total of the (meth)acrylate polymer (A) and the (meth)acrylate monomer mixture (B). In addition, the contents (parts by weight) of I651 and TPO are based on 100 parts by weight of the total of the (meth)acrylate polymer (A) and the (meth)acrylate monomer mixture (B).

[0138]

[0139] Experimental example

[0140] Viscosity measurement

[0141] For the photocurable compositions prepared in Examples 1 to 14 and Comparative Examples 1 to 4, the viscosity was measured using a Brookfield viscometer at a temperature of 25°C, a rotation speed of about 180 rpm, and a spindle number 40. The measured viscosity values ​​are shown in Tables 4 to 6 below.

[0142]

[0143] Adhesive strength measurement

[0144] In order to measure the adhesive strength of the photocurable compositions manufactured in Examples 1 to 14 and Comparative Examples 1 to 4, a 180 peel test was performed with reference to ASTM D3330.

[0145] Specifically, the photocurable composition manufactured in Example 1 was applied to a thickness of 50 μm on soda lime glass having a width of 25 mm, a length of 40 mm, and a thickness of 1.1 mm, and irradiated with ultraviolet rays using a 365 nm UV LED at a cumulative light dose of 600 mJ / cm 2 It was investigated and hardened as a condition.

[0146] Afterwards, a PET film measuring 25 mm in width, 60 mm in length, and 0.1 mm in thickness was bonded to the cured photocurable composition, and then light having a wavelength of 315 to 400 nm was irradiated using a metal mercury lamp at a cumulative light dose of 1000 mJ / cm. 2 It was investigated and confirmed as a condition.

[0147] Through this, 50 ㎛ thick adhesive strength specimens were manufactured, and the manufactured specimens were subjected to tensile testing at a tensile speed of 300 mm / min using a UTM universal testing machine 5566 to measure the adhesive strength. In addition, the adhesive strength of the photocurable compositions manufactured in Examples 2 to 14 and Comparative Examples 1 to 4 was measured in the same manner as above. The measured adhesive strength values ​​are shown in Tables 4 to 6 below.

[0148]

[0149] Temperature range volatilization (weight loss) measurement

[0150] Using a TGA (Thermogravimetric Analyzer) device, the photocurable composition manufactured in Example 1 was sampled and its initial weight was measured. Thereafter, the volatilized weight was measured at 55°C for 30 minutes at a heating rate of 5°C / min. Thereafter, the percentage (%) of the volatilized weight (B) / initial weight (A) was calculated and shown in Tables 4 to 6 below.

[0151] In addition, for the photocurable compositions manufactured in Examples 2 to 14 and Comparative Examples 1 to 4, the percentage (%) of the volatilized weight (B) / initial weight (A) was calculated in the same manner as above, and is shown in Tables 4 to 6 below.

[0152]

[0153] Decap time (inkjet standby time) measurement

[0154] In the inkjet head (KM1024) nozzle of the inkjet equipment, the time until the nozzle becomes clogged due to ink volatilization over time was measured.

[0155] Specifically, the photocurable composition manufactured in Example 1 was prepared as ink, and the ink was supplied into the nozzle by purging the ink through an inkjet device. Thereafter, a glass having a width of 25 mm, a height of 40 mm, and a thickness of 0.5 mm was placed under the inkjet head, and ink was ejected in place at 1 KHz for 0.3 seconds to check whether the ink was ejected normally from the inkjet nozzle. This was repeatedly ejected over time to measure the time until the nozzle became clogged.

[0156] Figure 1 is a photograph showing a state of ejection without nozzle clogging and a state of ejection with nozzle clogging in an experimental example of measuring decap time according to one embodiment of the present invention. Specifically, Figure 1 (a) is a photograph showing a pattern formed by ejecting ink without nozzle clogging, and Figure 1 (b) is a photograph showing a pattern formed by ejecting ink with nozzle clogging.

[0157] That is, when a pattern such as (b) of Fig. 1 is formed, it is determined that the ink nozzle is clogged, and the time for which the ink nozzle is clogged is measured and evaluated as the decap time.

[0158]

[0159] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Viscosity (Cp) 28.1 26.0 24.4 24.2 24.3 26.1 26.0 26.2 Adhesive strength (kgf) 0.4 0.4 0.7 0.7 0.6 0.6 0.5 B / A; TGA@55℃ (%) 7.2 3.7 5 4.5 4.8 4 3.5 3.7 Decap time (min) 60 34 0 27 0 31 0 30 0 33 0 36 0 34 0

[0160] Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Viscosity (Cp) 37.3 39.9 23.5 34.2 39.6 4 2.1 Adhesive strength (kgf) 1.3 0.9 0.6 0.9 1.10.9 B / A; TGA@55℃ (%) 7.6 6.2 5.5 3.9 8.6 9.2 Decap time (min) 60 120 240 330 30 10

[0161] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Viscosity (Cp) 19.1 18.8 20.7 20.0 Adhesive Strength (kgf) 0.6 0.6 0.5 0.5 B / A; TGA@55℃ (%) 10 15 11 16 Decap Time (min) 3 14 1

[0162] Referring to Tables 4 to 6 above, it was confirmed that the photocurable compositions prepared in Examples 1 to 14 of the present invention implemented excellent adhesive strength after photocuring. In addition, it was confirmed that the photocurable compositions prepared in Examples 1 to 14 of the present invention implemented excellent thermal stability in a temperature range volatilization measurement experiment compared to the photocurable compositions prepared in Comparative Examples 1 to 4. Furthermore, it was confirmed that the photocurable compositions prepared in Examples 1 to 14 of the present invention very effectively increased the decap time compared to the photocurable compositions prepared in Comparative Examples 1 to 4. Therefore, it can be seen that the photocurable composition according to one embodiment of the present invention has excellent thermal stability, so that volatilization is suppressed when applied to an inkjet process, thereby effectively increasing the decap time of the nozzle. Furthermore, it can be seen that the photocurable composition according to one embodiment of the present invention can have excellent adhesiveness, so that it can be easily applied to a display device.

Claims

1. (Meth)acrylate polymer; (meth)acrylate monomer mixture; and Including photoinitiators; The above (meth)acrylate monomer mixture is a photocurable composition comprising at least two (meth)acrylate monomers having a vapor pressure of 0.001 mmHg or more and 0.1 mmHg or less.

2. In paragraph 1, A photocurable composition wherein the (meth)acrylate polymer contains two or more (meth)acrylate functional groups.

3. In paragraph 1, A photocurable composition, wherein the content of the (meth)acrylate polymer is 10 parts by weight or more and 50 parts by weight or less, based on 100 parts by weight of the total mixture of the (meth)acrylate polymer and the (meth)acrylate monomer.

4. In paragraph 1, A photocurable composition, wherein the content of the (meth)acrylate monomer mixture is 60 parts by weight or more and 85 parts by weight or less, based on 100 parts by weight of the total of the (meth)acrylate polymer and (meth)acrylate monomer mixture.

5. In paragraph 1, The above (meth)acrylate monomer mixture is A photocurable composition comprising a first (meth)acrylate monomer having a vapor pressure of 0.001 mmHg or more and 0.01 mmHg or less.

6. In paragraph 5, A photocurable composition, wherein the content of the first (meth)acrylate monomer is 20 parts by weight or more and 80 parts by weight or less, based on 100 parts by weight of the total mixture of the (meth)acrylate polymer and the (meth)acrylate monomer.

7. In paragraph 5, The above (meth)acrylate monomer mixture is A photocurable composition comprising a second (meth)acrylate monomer having a vapor pressure of more than 0.01 mmHg and less than or equal to 0.1 mmHg.

8. In paragraph 7, A photocurable composition, wherein the content of the second (meth)acrylate monomer is 30 parts by weight or more and 60 parts by weight or less, based on 100 parts by weight of the total mixture of the (meth)acrylate polymer and the (meth)acrylate monomer.

9. In paragraph 7, The above (meth)acrylate monomer mixture is A photocurable composition wherein the content ratio of the first (meth)acrylate monomer and the second (meth)acrylate monomer is 1:1.1 to 1:2.

5.

10. In paragraph 7, The above (meth)acrylate monomer mixture is A photocurable composition wherein the content ratio of the first (meth)acrylate monomer and the second (meth)acrylate monomer is 1:1.4 to 1:2.

4.

11. In paragraph 1, A photocurable composition wherein the content of the photoinitiator is 0.1 part by weight or more and 5 parts by weight or less, based on 100 parts by weight of the total mixture of the (meth)acrylate polymer and the (meth)acrylate monomer.

12. In paragraph 1, A photocurable composition having a viscosity of 10 cp or more and 45 cp or less.

13. In paragraph 1, The above photocurable composition is a photocurable composition satisfying the following mathematical formula 1: [Mathematical Formula 1] 0.02 ≤ B / A < 0.1 In the above mathematical expression 1, A is the weight of the photocurable composition sample before heating, and B is the weight of the photocurable composition sample volatilized after heating at 55°C for 30 minutes at a heating rate of 5°C / min.

14. In paragraph 1, The above photocurable composition is a photocurable composition satisfying the following mathematical formula 2: [Mathematical formula 2] 0.039 ≤ B / A < 0.05 In the above mathematical expression 2, A is the weight of the photocurable composition sample before heating, and B is the weight of the photocurable composition sample volatilized after heating at 55°C for 30 minutes at a heating rate of 5°C / min.

15. An adhesive comprising a photocurable composition according to paragraph 1.

16. A display device comprising an adhesive layer comprising a photocurable composition according to paragraph 1.

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