Multilayer sheet and multilayer electronic device

Abstract

An example multilayer sheet includes an elastic layer and an adhesive layer disposed on the elastic layer. The storage modulus of the multilayer sheet measured at 20 DEG C is from 10 MPa to 1000 MPa (inclusive). Even if repeated bending or rolling occurs in a wide temperature range, the multilayer sheet and the like can inhibit peeling from the surface of an adhering object, do not generate interlayer separation, and have the characteristic of external impact resistance.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Korean Patent Application No. 10-2022-0091016 filed on Jul. 22, 2022, the contents of which are incorporated herein by reference in their entirety.

[0003] Examples relate to multilayer sheets that may be suitable for protecting displays and the like, and multilayer electronic devices including the same. Background Art

[0004] With the diversification of mobile devices such as mobile phones, smartphones, tablets, ATMs, self-service machines and other information processing terminals, surface protection sheets are widely used. In addition, with the emergence of various forms of display devices such as folding, flexible, and curling, there is a demand not only for surface hardness to suppress surface scratches, but also for sufficient durability against repeated folding and rolling. In addition, when applied to display screens, optical properties are of course also required.

[0005] Prior art literature

[0006] Korean Patent No. 10-1798759

[0007] Korean Patent No. 10-1810422 Summary of the invention

[0008] Technical issues

[0009] The purpose of the embodiment is to provide a multilayer sheet or the like which is resistant to external impacts and can suppress peeling from the surface of an adhered object and does not cause interlayer separation even when repeatedly bent or rolled in a wide temperature range.

[0010] Technical Solution

[0011] A multilayer sheet according to an embodiment of the present specification includes an elastic layer and an adhesive layer disposed on the elastic layer.

[0012] The storage modulus of the multilayer sheet measured at 20° C. is 10 MPa or more and 2000 MPa or less.

[0013] The multilayer sheet may have an RSM value of 1 or more and 200 or less of the following formula 1 measured at 20°C.

[0014] [Formula 1]

[0015] RSM=SM E / SM B

[0016] In Formula 1, the SME is the storage modulus value of the elastic layer.

[0017] The SM B is the storage modulus value of the adhesive layer.

[0018] The absolute value of the value obtained by subtracting the storage modulus value measured at 60° C. from the storage modulus value measured at 20° C. of the multilayer sheet may be 1000 MPa or less.

[0019] The absolute value of the value obtained by subtracting the storage modulus value measured at 20° C. from the storage modulus value measured at −40° C. of the multilayer sheet may be 1500 MPa or less.

[0020] The storage modulus of the elastic layer measured at 20° C. may be 10 MPa or more and 3000 MPa or less.

[0021] The storage modulus of the adhesive layer measured at 20° C. may be 1 MPa or more and 50 MPa or less.

[0022] The adhesive force of the adhesive layer after curing may be greater than 2 N / inch.

[0023] The adhesive force per unit thickness (1 μm) of the adhesive layer after curing may be 0.8 N / inch or more.

[0024] A multilayer electronic device according to another embodiment of the present specification includes: the multilayer sheet, and a light-emitting functional layer disposed below the multilayer sheet.

[0025] Effects of the Invention

[0026] The multilayer sheet or the like according to the example can suppress peeling from the surface of the adhered object even when repeatedly bent or rolled in a wide temperature range, and separation between layers does not occur, and has the characteristic of being resistant to external impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a conceptual diagram for explaining a multilayer sheet according to an embodiment of the present specification.

[0028] Figure 2 This is a conceptual diagram for explaining a multilayer sheet according to another embodiment of the present specification.

[0029] Figure 3 This is a conceptual diagram for explaining a multilayer sheet according to still another embodiment of the present specification.

[0030] Figure 4 This is a conceptual diagram for explaining a multilayer sheet according to still another embodiment of the present specification.

[0031] Figure 5This is a conceptual diagram for explaining a multilayer electronic device according to another embodiment of the present specification.

[0032] Figures 6 to 12 It is a graph showing the storage modulus measurement values ​​at different temperatures of Examples and Comparative Examples. DETAILED DESCRIPTION

[0033] The following is a detailed description of the embodiments so that those skilled in the art can easily implement the invention. However, the embodiments are not limited to the embodiments described herein, but can be embodied in various forms.

[0034] The degree terms "about", "substantially", etc. used in this specification are used to indicate the inherent manufacturing and material tolerances in the mentioned meaning, with the meaning of the numerical value or close to the numerical value, and to prevent unscrupulous infringers from improperly taking advantage of the public content that mentions exact or absolute values ​​to assist in understanding the examples.

[0035] Throughout the present specification, the term "combination thereof" included in the Markush form expression means a mixture or combination of one or more selected from the group consisting of a plurality of structural elements described in the Markush form expression, and means including one or more selected from the group consisting of the structural elements.

[0036] Throughout the present specification, the description "A and / or B" means "A, B, or A and B".

[0037] Throughout the present specification, terms such as “first”, “second” or “A”, “B” and the like are used to distinguish the same terms unless otherwise specified.

[0038] In the present specification, B being located at A means that B is located at A or another layer may be provided therebetween, and B being located at A should not be construed as limiting B in a manner of being in contact with the surface of A.

[0039] In the present specification, as long as there is no special explanation, the expression of a single number should be construed as including the meaning of the single number or plural numbers explained in the context.

[0040] The resin described in this specification is interpreted as including the resin itself and the compound derived from the resin. For example, the polyester resin described in this specification means the polyester resin and the derivative of the polyester resin.

[0041] In this specification, when the adhesive layer is a curable adhesive layer, the storage modulus value of the adhesive layer corresponds to the value measured from the adhesive layer after curing.

[0042] In this specification, when the adhesive layer included in the multilayer sheet is a curable adhesive layer, the storage modulus value of the multilayer sheet corresponds to the value measured from the multilayer sheet after curing the adhesive layer in the multilayer sheet.

[0043] The inventors of the example controlled the storage modulus value of the multilayer sheet having an elastic layer and an adhesive layer, etc. As a result, the inventors confirmed through experiments that when the multilayer sheet is attached to a flexible attachment object such as a flexible display, even if the attachment object is repeatedly bent or rolled, the multilayer sheet will not be lifted from the surface of the attachment object and can stably protect the attachment object, thereby completing the example.

[0044] The following describes the examples in detail.

[0045] Figure 1 1 is a conceptual diagram illustrating the structure of a multilayer sheet of an example in cross section. Figure 1 The multilayer sheet of the example is described in further detail.

[0046] The multi-layer sheet 100 of the example includes an elastic layer 10 and an adhesive layer 20 disposed on the elastic layer 10 .

[0047] Multilayer

[0048] The storage modulus of the multilayer sheet 100 measured at 20° C. is 10 MPa or more and 2000 MPa or less.

[0049] In the example, the storage modulus of the multilayer sheet 100 at different measurement temperatures can be controlled within a predetermined range in the example. In this case, the modulus difference between the flexible display having a relatively high storage modulus value and the multilayer sheet 100 can be reduced. Thus, the multilayer sheet 100 attached to the display can be effectively prevented from peeling off from the surface of the display due to repeated bending. Further, the display can be stably protected from external impact.

[0050] The storage modulus of the multilayer sheet 100 at different measurement temperatures was measured according to ASTM D4065. Specifically, the storage modulus of the multilayer sheet 100 at different measurement temperatures was measured using a viscoelasticity measuring device at a temperature range of -50°C to 100°C with a heating rate of 5°C / min.

[0051] Illustratively, the storage modulus may be measured using a DMA7100 model manufactured by Hitachi.

[0052] The storage modulus of the multilayer sheet 100 measured at 20° C. may be greater than 10 MPa and less than 2000 MPa. The storage modulus value may be greater than 20 MPa. The storage modulus value may be greater than 50 MPa. The storage modulus value may be greater than 100 MPa. The storage modulus value may be greater than 200 MPa. The storage modulus value may be greater than 300 MPa. The storage modulus value may be less than 1800 MPa. The storage modulus value may be less than 1500 MPa. The storage modulus value may be less than 1200 MPa. The storage modulus value may be less than 1000 MPa. When attached to a flexible display, such a multilayer sheet may be stably attached to the surface of the display even when the display is repeatedly bent.

[0053] The storage modulus of the multilayer sheet 100 measured at 0°C may be 20 MPa or more and 2500 MPa or less. The storage modulus value may be 30 MPa or more. The storage modulus value may be 40 MPa or more. The storage modulus value may be 100 MPa or more. The storage modulus value may be 200 MPa or more. The storage modulus value may be 350 MPa or more. The storage modulus value may be 2000 MPa or less. The storage modulus value may be 1500 MPa or less. The storage modulus value may be 1000 MPa or less. The storage modulus value may be 700 MPa or less.

[0054] The storage modulus of the multilayer sheet 100 measured at -20°C may be 30 MPa or more and 3000 MPa or less. The storage modulus value may be 50 MPa or more. The storage modulus value may be 100 MPa or more. The storage modulus value may be 200 MPa or more. The storage modulus value may be 300 MPa or more. The storage modulus value may be 400 MPa or more. The storage modulus value may be 2500 MPa or less. The storage modulus value may be 2000 MPa or less. The storage modulus value may be 1500 MPa or less. The storage modulus value may be 1000 MPa or less. The storage modulus value may be 700 MPa or less.

[0055] The storage modulus of the multilayer sheet 100 measured at -40°C may be 50 MPa or more and 4000 MPa or less.

[0056] The storage modulus value may be greater than 100 MPa. The storage modulus value may be greater than 200 MPa. The storage modulus value may be greater than 300 MPa. The storage modulus value may be greater than 400 MPa. The storage modulus value may be greater than 500 MPa. The storage modulus value may be less than 3500 MPa. The storage modulus value may be less than 3000 MPa. The storage modulus value may be less than 2500 MPa. The storage modulus value may be less than 2000 MPa. The storage modulus value may be less than 1500 MPa. The storage modulus value may be less than 1000 MPa. The storage modulus value may be less than 600 MPa.

[0057] The storage modulus of the multilayer sheet 100 measured at 40° C. may be 5 MPa or more and 2000 MPa or less.

[0058] The storage modulus value may be greater than 10 MPa. The storage modulus value may be greater than 20 MPa. The storage modulus value may be greater than 50 MPa. The storage modulus value may be greater than 100 MPa. The storage modulus value may be greater than 150 MPa. The storage modulus value may be less than 1500 MPa. The storage modulus value may be less than 1200 MPa. The storage modulus value may be less than 1000 MPa. The storage modulus value may be less than 800 MPa. The storage modulus value may be less than 700 MPa.

[0059] The storage modulus of the multilayer sheet 100 measured at 60° C. may be 3 MPa or more and 800 MPa or less. The storage modulus value may be 10 MPa or more. The storage modulus value may be 20 MPa or more. The storage modulus value may be 50 MPa or more. The storage modulus value may be 80 MPa or more. The storage modulus value may be 100 MPa or more. The storage modulus value may be 600 MPa or less. The storage modulus value may be 400 MPa or less. The storage modulus value may be 300 MPa or less.

[0060] The storage modulus of the multilayer sheet 100 measured at 80° C. may be 1 MPa or more and 500 MPa or less. The storage modulus value may be 5 MPa or more. The storage modulus value may be 10 MPa or more. The storage modulus value may be 30 MPa or more. The storage modulus value may be 50 MPa or more. The storage modulus value may be 400 MPa or less. The storage modulus value may be 300 MPa or less. The storage modulus value may be 250 MPa or less. The storage modulus value may be 200 MPa or less.

[0061] In this case, the multilayer sheet can be stably attached to the flexible display over a wide temperature range.

[0062] The absolute value of the value obtained by subtracting the storage modulus value of the multilayer sheet 100 measured at 40°C from the storage modulus value of the multilayer sheet 100 measured at 20°C may be 700 MPa or less. The absolute value may be 500 MPa or less. The absolute value may be 300 MPa or less. The absolute value may be 100 MPa or less. The absolute value may be 50 MPa or less. The absolute value may be 20 MPa or less. The absolute value may be 10 MPa or less. The absolute value may be 1 MPa or more.

[0063] The absolute value of the value obtained by subtracting the storage modulus value of the multilayer sheet 100 measured at 60°C from the storage modulus value of the multilayer sheet 100 measured at 20°C may be 1000 MPa or less. The absolute value may be 700 MPa or less. The absolute value may be 500 MPa or less. The absolute value may be 300 MPa or less. The absolute value may be 100 MPa or less. The absolute value may be 50 MPa or less. The absolute value may be 30 MPa or less. The absolute value may be 15 MPa or less. The absolute value may be 1 MPa or more.

[0064] The absolute value of the value obtained by subtracting the storage modulus value of the multilayer sheet 100 measured at 80°C from the storage modulus value of the multilayer sheet 100 measured at 20°C may be 1000 MPa or less. The absolute value may be 700 MPa or less. The absolute value may be 500 MPa or less. The absolute value may be 300 MPa or less. The absolute value may be 100 MPa or less. The absolute value may be 50 MPa or less. The absolute value may be 30 MPa or less. The absolute value may be 1 MPa or more.

[0065] In this case, the warping phenomenon of the multilayer sheet due to the temperature rise can be effectively suppressed.

[0066] The absolute value of the value obtained by subtracting the storage modulus value of the multilayer sheet 100 measured at 20°C from the storage modulus value of the multilayer sheet 100 measured at 0°C may be 500 MPa or less. The absolute value may be 400 MPa or less. The absolute value may be 300 MPa or less. The absolute value may be 200 MPa or less. The absolute value may be 100 MPa or less. The absolute value may be 50 MPa or less. The absolute value may be 30 MPa or less. The absolute value may be 1 MPa or more.

[0067] The absolute value of the value obtained by subtracting the storage modulus value of the multilayer sheet 100 measured at 20°C from the storage modulus value of the multilayer sheet 100 measured at -20°C may be 1000 MPa or less. The absolute value may be 800 MPa or less. The absolute value may be 600 MPa or less. The absolute value may be 500 MPa or less. The absolute value may be 300 MPa or less. The absolute value may be 200 MPa or less. The absolute value may be 100 MPa or less. The absolute value may be 50 MPa or less. The absolute value may be 1 MPa or more.

[0068] The absolute value of the value obtained by subtracting the storage modulus value of the multilayer sheet 100 measured at 20°C from the storage modulus value of the multilayer sheet 100 measured at -40°C may be 1500MPa or less. The absolute value may be 1200MPa or less. The absolute value may be 1000MPa or less. The absolute value may be 700MPa or less. The absolute value may be 500MPa or less. The absolute value may be 200MPa or less. The absolute value may be 100MPa or less. The absolute value may be 50MPa or less. The absolute value may be 30MPa or less. The absolute value may be 20MPa or less. The absolute value may be 1MPa or more.

[0069] In this case, as the temperature decreases, the bending characteristics of the multilayer sheet also decrease, thereby effectively suppressing the multilayer sheet from being peeled off from the display.

[0070] The multilayer sheet 100 may have an RSM value of 1 or more and 200 or less of the following formula 1 measured at 20°C.

[0071] [Formula 1]

[0072] RSM=SM E / SM B

[0073] In Formula 1, the SM E is the storage modulus value of the elastic layer.

[0074] The SM B is the storage modulus value of the adhesive layer.

[0075] The example can control the RSM value of the multilayer sheet 100 within a preset range in the example. Thus, not only can the multilayer sheet 100 be effectively prevented from peeling off from the surface of the attached object by adjusting the mechanical property difference between the layers in the multilayer sheet 100, but also the interlayer peeling in the multilayer sheet can be effectively prevented.

[0076] The description of the method of measuring the storage modulus of the elastic layer 10 and the adhesive layer 20 overlaps with the above content, and thus is omitted.

[0077] The RSM value of the multilayer sheet 100 measured at 20° C. may be 1 or more and 200 or less. The RSM value may be 3 or more. The RSM value may be 5 or more. The RSM value may be 10 or more. The RSM value may be 15 or more. The RSM value may be 20 or more. The RSM value may be 180 or less. The RSM value may be 150 or less. The RSM value may be 120 or less. The RSM value may be 100 or less. The RSM value may be 80 or less.

[0078] The RSM value of the multilayer sheet 100 measured at 40° C. may be 5 or more and 400 or less. The RSM value may be 10 or more. The RSM value may be 20 or more. The RSM value may be 30 or more. The RSM value may be 45 or more. The RSM value may be 55 or more. The RSM value may be 350 or less. The RSM value may be 300 or less. The RSM value may be 250 or less. The RSM value may be 220 or less. The RSM value may be 200 or less.

[0079] The RSM value of the multilayer sheet 100 measured at 0° C. may be 0.1 or more and 100 or less. The RSM value may be 1 or more. The RSM value may be 3 or more. The RSM value may be 5 or more. The RSM value may be 10 or more. The RSM value may be 80 or less. The RSM value may be 65 or less. The RSM value may be 50 or less.

[0080] The RSM value of the multilayer sheet 100 measured at -20°C may be 0.5 or more and 75 or less. The RSM value may be 1 or more. The RSM value may be 3 or more. The RSM value may be 5 or more. The RSM value may be 7 or more. The RSM value may be 60 or less. The RSM value may be 50 or less. The RSM value may be 40 or less.

[0081] The RSM value of the multilayer sheet 100 measured at -40°C may be 0.7 or more and 60 or less. The RSM value may be 1 or more. The RSM value may be 3.5 or more. The RSM value may be 5.5 or more. The RSM value may be 7.5 or more. The RSM value may be 50 or less. The RSM value may be 30 or less. The RSM value may be 20 or less.

[0082] In this case, it is possible to effectively suppress the adhesive layer from being peeled off due to a difference in modulus between the adhesive layer and the elastic layer or a difference in modulus between the adhesive layer and the display.

[0083] The adhesive force of the multilayer sheet 100 may be 2 N / inch or more.

[0084] The embodiment can control the adhesive force of the multilayer sheet 100. Even when applied to a display that is repeatedly bent or rolled, the multilayer sheet 100 can exhibit stable adhesion.

[0085] The adhesive strength of the multilayer sheet 100 was measured after the adhesive layer 20 was cured. The adhesive strength of the multilayer sheet 100 was measured by a 180° peel test using an Advanced Force Gauge. During the measurement, the peeling speed was 300 mm / min, and the adherend was a glass plate.

[0086] For example, the advanced force gauge may be a Mecmesin AFG50 model, and the adherend may be an Avanstrate NA32G model.

[0087] The adhesive force of the multilayer sheet 100 may be 2 N / inch or more. The adhesive force may be 3 N / inch or more. The adhesive force may be 5 N / inch or more. The adhesive force may be 8 N / inch or more. The adhesive force may be 10 N / inch or more. The adhesive force may be 25 N / inch or less. The adhesive force may be 23 N / inch or less. The adhesive force may be 20 N / inch or less. The adhesive force may be 18 N / inch or less. In this case, the adhesion of the multilayer sheet may be further improved.

[0088] The thickness of the multilayer sheet 100 may be 10 μm or more. The thickness may be 15 μm or more. The thickness may be 20 μm or more. The thickness may be 30 μm or more. The thickness may be 1000 μm or less. The thickness may be 800 μm or less. The thickness may be 500 μm or less. The thickness may be 300 μm or less. The thickness may be 200 μm or less. The thickness may be 100 μm or less. The thickness may be 50 μm or less. The thickness may be 10 μm or more. In this case, the multilayer sheet may stably protect a display or other protected object from external impact.

[0089] Figure 2 This is a conceptual diagram for explaining a multilayer sheet according to another embodiment of the present specification. Figure 2 The example is further explained in detail.

[0090] The multilayer sheet 100 may include: an adhesive layer 20 disposed above the elastic layer 10; and an adhesive layer 20 disposed below the elastic layer 10. The multilayer sheet having such a structure may be used as an adhesive film.

[0091] The multilayer sheet 100 may include one surface and the other surface. In the multilayer sheet 100, the adhesive layer 20 may be disposed as the outermost layer on the one surface side and the other surface side. The multilayer sheet having such a structure is suitable for use as an adhesive film for a display.

[0092] Figure 3 This is a conceptual diagram for explaining a multilayer sheet according to another embodiment of the present specification. Figure 3 The example is further explained in detail.

[0093] The multilayer sheet 100 may include: a transparent layer 30 disposed on the adhesive layer 20 ; and a coating layer 40 disposed on the transparent layer 30 .

[0094] The transparent layer 30 may be disposed in contact with the adhesive layer 20. The transparent layer 30 may be located on the adhesive layer 20 without being in contact with the adhesive layer 20.

[0095] The coating layer 40 may be disposed in contact with the transparent layer 30. The coating layer 40 may be disposed on the transparent layer 30 without being in contact with the transparent layer 30.

[0096] The transparent layer 30 may be used as a base layer for the coating layer 40 .

[0097] The lower surface of the coating layer 40 may face the transparent layer 30 , and the upper surface of the coating layer 40 may be the outermost surface exposed to the outside.

[0098] The coating 40 may be a curable coating.

[0099] Figure 4 This is a conceptual diagram for explaining a multilayer sheet according to another embodiment of the present specification. Figure 4 The example is further explained in detail.

[0100] The multilayer sheet 100 may further include a release film 50 above the adhesive layer 20 .

[0101] The release film 50 may be disposed in contact with the upper surface of the adhesive layer 20. The release film 50 may be disposed on the adhesive layer 20 via another layer located between the lower surface of the release film 50 and the upper surface of the adhesive layer 20.

[0102] The release substrate layer 52 may be used as a base layer of the release layer 51 .

[0103] The release film 50 may include: a release layer 51 disposed on the adhesive layer 20 ; and a release substrate layer 52 disposed on the release layer 51 .

[0104] The release layer 51 may be a cured layer of a silicone resin composition containing a fluorine group. Specifically, the release layer 51 may be a cured layer of a release coating liquid containing an organopolysiloxane containing a fluorine group and an organopolysiloxane containing an alkenyl group.

[0105] The release substrate layer 52 is not limited as long as it is commonly used in the field of substrate films. For example, a polyethylene terephthalate film or the like can be used as the release substrate layer 52 .

[0106] Elastic layer

[0107] In one embodiment, the elastic layer 10 can have a storage modulus value controlled at different measurement temperatures. This can provide the multilayer sheet with excellent bending properties in a wide temperature range and stably protect the display.

[0108] The method for measuring the storage modulus values ​​of the elastic layer 10 at different temperatures is the same as the method for measuring the storage modulus values ​​of the multilayer sheet at different temperatures described above.

[0109] The storage modulus value of the elastic layer 10 measured at 20° C. may be 10 MPa or more. The storage modulus value may be 50 MPa or more. The storage modulus value may be 100 MPa or more. The storage modulus value may be 200 MPa or more. The storage modulus value may be 300 MPa or more. The storage modulus value may be 3000 MPa or less. The storage modulus value may be 2500 MPa or less. The storage modulus value may be 2000 MPa or less. The storage modulus value may be 1500 MPa or less. The storage modulus value may be 1200 MPa or less.

[0110] The storage modulus value of the elastic layer 10 measured at 40° C. may be 10 MPa or more. The storage modulus value may be 50 MPa or more. The storage modulus value may be 100 MPa or more. The storage modulus value may be 200 MPa or more. The storage modulus value may be 1200 MPa or less. The storage modulus value may be 1000 MPa or less. The storage modulus value may be 800 MPa or less. The storage modulus value may be 700 MPa or less.

[0111] The storage modulus value of the elastic layer 10 measured at 60° C. may be 10 MPa or more. The storage modulus value may be 50 MPa or more. The storage modulus value may be 100 MPa or more. The storage modulus value may be 700 MPa or less. The storage modulus value may be 500 MPa or less. The storage modulus value may be 300 MPa or less.

[0112] The storage modulus value of the elastic layer 10 measured at 80° C. may be 10 MPa or more. The storage modulus value may be 20 MPa or more. The storage modulus value may be 50 MPa or more. The storage modulus value may be 70 MPa or more. The storage modulus value may be 500 MPa or less. The storage modulus value may be 350 MPa or less. The storage modulus value may be 200 MPa or less. The storage modulus value may be 170 MPa or less.

[0113] The storage modulus value of the elastic layer 10 measured at 0° C. may be 30 MPa or more. The storage modulus value may be 50 MPa or more. The storage modulus value may be 100 MPa or more. The storage modulus value may be 200 MPa or more. The storage modulus value may be 300 MPa or more. The storage modulus value may be 2200 MPa or less. The storage modulus value may be 1800 MPa or less. The storage modulus value may be 1500 MPa or less. The storage modulus value may be 1200 MPa or less. The storage modulus value may be 1000 MPa or less. The storage modulus value may be 800 MPa or less.

[0114] The storage modulus value of the elastic layer 10 measured at -20°C may be 50 MPa or more. The storage modulus value may be 100 MPa or more. The storage modulus value may be 150 MPa or more. The storage modulus value may be 200 MPa or more. The storage modulus value may be 300 MPa or more. The storage modulus value may be 350 MPa or more. The storage modulus value may be 400 MPa or more. The storage modulus value may be 2400 MPa or less. The storage modulus value may be 2000 MPa or less. The storage modulus value may be 1500 MPa or less. The storage modulus value may be 1200 MPa or less. The storage modulus value may be 1000 MPa or less. The storage modulus value may be 800 MPa or less.

[0115] The storage modulus value of the elastic layer 10 measured at -40°C may be 80 MPa or more. The storage modulus value may be 200 MPa or more. The storage modulus value may be 350 MPa or more. The storage modulus value may be 500 MPa or more. The storage modulus value may be 2600 MPa or less. The storage modulus value may be 2300 MPa or less. The storage modulus value may be 2000 MPa or less. The storage modulus value may be 1700 MPa or less. The storage modulus value may be 1500 MPa or less. The storage modulus value may be 1200 MPa or less. The storage modulus value may be 1000 MPa or less. The storage modulus value may be 850 MPa or less.

[0116] In this case, the elastic layer can help impart stable bending properties to the multilayer sheet over a wide temperature range.

[0117] The absolute value of the value obtained by subtracting the storage modulus value of the elastic layer 10 measured at 40°C from the storage modulus value of the elastic layer 10 measured at 20°C may be 1000 MPa or less. The absolute value may be 850 MPa or less. The absolute value may be 550 MPa or less. The absolute value may be 450 MPa or less. The absolute value may be 300 MPa or less. The absolute value may be 200 MPa or less. The absolute value may be 0.1 MPa or more.

[0118] The absolute value of the value obtained by subtracting the storage modulus value of the elastic layer 10 measured at 60°C from the storage modulus value of the elastic layer 10 measured at 20°C may be 2000 MPa or less. The absolute value may be 1800 MPa or less. The absolute value may be 1500 MPa or less. The absolute value may be 1300 MPa or less. The absolute value may be 1000 MPa or less. The absolute value may be 800 MPa or less. The absolute value may be 500 MPa or less. The absolute value may be 300 MPa or less. The absolute value may be 1 MPa or more.

[0119] The absolute value of the value obtained by subtracting the storage modulus value of the elastic layer 10 measured at 80°C from the storage modulus value of the elastic layer 10 measured at 20°C may be 2000 MPa or less. The absolute value may be 1800 MPa or less. The absolute value may be 1500 MPa or less. The absolute value may be 1300 MPa or less. The absolute value may be 1000 MPa or less. The absolute value may be 800 MPa or less. The absolute value may be 500 MPa or less. The absolute value may be 350 MPa or less. The absolute value may be 1 MPa or more.

[0120] The absolute value of the value obtained by subtracting the storage modulus value of the elastic layer 10 measured at 20°C from the storage modulus value of the elastic layer 10 measured at 0°C may be 1000 MPa or less. The absolute value may be 850 MPa or less. The absolute value may be 550 MPa or less. The absolute value may be 350 MPa or less. The absolute value may be 180 MPa or less. The absolute value may be 1 MPa or more.

[0121] The absolute value of the value obtained by subtracting the storage modulus value of the elastic layer 10 measured at 20°C from the storage modulus value of the elastic layer 10 measured at -20°C may be 1000 MPa or less. The absolute value may be 850 MPa or less. The absolute value may be 550 MPa or less. The absolute value may be 350 MPa or less. The absolute value may be 180 MPa or less. The absolute value may be 1 MPa or more.

[0122] The absolute value of the value obtained by subtracting the storage modulus value of the elastic layer 10 measured at 20°C from the storage modulus value of the elastic layer 10 measured at -40°C may be 1200 MPa or less. The absolute value may be 1000 MPa or less. The absolute value may be 800 MPa or less. The absolute value may be 600 MPa or less. The absolute value may be 500 MPa or less. The absolute value may be 400 MPa or less. The absolute value may be 1 MPa or more.

[0123] In this case, the display can be stably protected in a wide temperature range, and the bending characteristics of the elastic layer can be suppressed from excessively varying.

[0124] The elastic layer 10 may have a strength of 2500 kJ / m 2 The impact strength can be 3500 kJ / m 2 The impact strength can be 4500 kJ / m 2 The impact strength can be 5000 kJ / m 2 The impact strength can be 10000 kJ / m 2 The elastic layer having such characteristics can absorb external impact well and will not be easily broken or damaged.

[0125] The elastic layer 10 may have an absorption energy of 1.4 J or more. The absorption energy may be 1.5 J or more. The absorption energy may be 1.6 J or more. The absorption energy may be 2.0 J or less. The elastic layer having such characteristics may effectively mitigate the impact transmitted to the protected object.

[0126] The impact strength and the absorbed energy were measured in accordance with JIS K 7160.

[0127] The haze value of the elastic layer 10 may be 3% or less. The haze value may be 2% or less. The haze value may be 1.5% or less. The haze value may be 1.2% or less. The haze value may be 0.01% or more. The haze value may be 0.1% or more.

[0128] The visible light transmittance of the elastic layer 10 may be 85% or more. The transmittance may be 88% or more. The transmittance may be 90% or more. The transmittance may be 99.99% or less.

[0129] The elastic layer having such characteristics may have optical properties suitable for use as a protective layer for a display.

[0130] The yellow index (YI) of the elastic layer 10 may be 1 or less.

[0131] The yellow index may be a value measured using Color Meter Ultrascan Pro manufactured by Hunterlab in the YIE313 (D65 / 10) mode.

[0132] The value of the yellow index after the elastic layer 10 is exposed to ultraviolet rays with a wavelength of 280 nm to 360 nm at a power of 3.0 W for 72 hours minus the yellow index before exposure may be 2 or less. The value of the yellow index after the elastic layer 10 is exposed to ultraviolet rays with a wavelength of 280 nm to 360 nm at a power of 3.0 W for 72 hours minus the yellow index before exposure may be 1 or less. The value of the yellow index after the elastic layer 10 is exposed to ultraviolet rays with a wavelength of 280 nm to 360 nm at a power of 3.0 W for 72 hours minus the yellow index before exposure may be 0.1 or more. The elastic layer having such characteristics can have excellent ultraviolet durability in which yellowing of the coating layer is little or almost not caused even when exposed to ultraviolet rays.

[0133] In essence, the elastic layer 10 may not have a white turbidity (cloudy phenomenon) observed. In essence, the area where the white turbidity is observed in the elastic film may be less than 1% of the total area. In this case, the total area is based on the total area of ​​the film applicable to the product. The white turbidity can be objectively measured by haze measurement, and when the haze measurement value is greater than 1%, it can be considered that the white turbidity can be felt. The degree of the white turbidity can be adjusted by controlling the gelation degree and molecular weight distribution of the resin used in the manufacture of the elastic layer.

[0134] The elastic layer 10 may include polyether block amide (PEBA). The polyether block amide includes two phases, namely, a polyamide region as a rigid region and a polyether region as a flexible region. The melting point of the polyamide region may be above about 80°C, specifically, about 130°C to 180°C, and substantially, a hard region may be formed in a crystalline phase. The glass transition temperature of the polyether region may be below about -40°C, specifically, about -80°C to -40°C, and may exist in a low temperature region, thereby substantially forming an amorphous soft region.

[0135] Illustratively, the polyether block amide may be Arkema's EVONIK E, etc.

[0136] The elastic layer 10 may include a polymer including an amide residue as a repeating unit. The elastic layer 10 may be a plastic film including a polymer including an amide residue as a repeating unit. The elastic layer 10 may be an elastic film including a polymer including an amide residue as a repeating unit.

[0137] Based on all the polymers included in the elastic film, the amide residues may be 50 weight percent or more, or 60 weight percent or more. Based on all the polymers included in the elastic film, the amide residues may be 80 weight percent or less, or 70 weight percent or less. When a polymer having such characteristics is applied to the elastic film, an elastic film with better mechanical properties can be provided.

[0138] The elastic layer 10 may include elastic polyamide (long chain polyamide). For example, the elastic polyamide may be Arkema's wait.

[0139] The elastic layer 10 may include thermoplastic polyurethane (TPU), that is, may include a copolymer of a polyurethane block (PU) and a polyether block (PE), which is also called polyether polyurethane.

[0140] The elastic layer 10 may include copolyetherester (COPE).

[0141] The thickness of the elastic layer 10 may be 500 μm or less. The thickness may be 300 μm or less. The thickness may be 200 μm or less. The thickness may be 100 μm or less. The thickness may be 80 μm or less. The thickness may be 1 μm or more. The thickness may be 5 μm or more. The thickness may be 10 μm or more. In this case, the elastic layer may impart excellent impact resistance and bending properties to the multilayer sheet.

[0142] The elastic layer 10 can be formed using a resin composition for an elastic layer.

[0143] The elastic layer resin composition may include a polymer including an amide residue as a repeating unit. The elastic layer resin composition may include an elastic polyamide. The elastic layer resin composition may include a thermoplastic polyurethane. The elastic layer resin composition may include a copolyetherester (COPE).

[0144] The description of the resin overlaps with the above content, so the description is omitted.

[0145] The method of molding the elastic layer resin composition into the shape of the elastic layer may be any method applicable to the production of a film, and a melt extrusion method may be used as an example.

[0146] When the elastic layer resin composition is melt-extruded and molded into an elastic sheet, the melt-extrusion temperature may be 200° C. to 300° C. When the melt-extrusion is performed within this temperature range, the properties of the resin itself are not damaged, and fluidity can be imparted to the resin composition, thereby enabling smooth molding into a sheet shape.

[0147] The produced elastic layer may be passed through a roller in order to adjust the thickness of the elastic layer 10. If necessary, an elastic layer protection film may be laminated on the upper and lower sides of the elastic layer to form a laminate, and then the laminate may be passed through a roller.

[0148] Adhesive layer

[0149] In the example, the storage modulus value of the adhesive layer 20 at different measurement temperatures can be controlled to reduce the difference in modulus characteristics between the adhesive layer 20 and the elastic layer 10 in the multilayer sheet 100 within a wide temperature range. As a result, the adhesive layer 20 can be prevented from peeling off from the elastic layer 10 during repeated bending. At the same time, the multilayer sheet 100 can be prevented from peeling off from the flexible display due to the difference in bending characteristics between the adhesive layer 20 and the display.

[0150] The method for measuring the storage modulus of the adhesive layer 20 at different temperatures is the same as the method for measuring the storage modulus of the multilayer sheet at different temperatures described above.

[0151] The storage modulus value of the adhesive layer 20 measured at 20° C. may be 1 MPa or more. The storage modulus value may be 5 MPa or more. The storage modulus value may be 7 MPa or more. The storage modulus value may be 100 MPa or less. The storage modulus value may be 80 MPa or less. The storage modulus value may be 50 MPa or less. The storage modulus value may be 20 MPa or less.

[0152] The storage modulus value of the adhesive layer 20 measured at 40° C. may be 0.1 MPa or more. The storage modulus value may be 0.5 MPa or more. The storage modulus value may be 1 MPa or more. The storage modulus value may be 2 MPa or more. The storage modulus value may be 30 MPa or less. The storage modulus value may be 20 MPa or less. The storage modulus value may be 10 MPa or less.

[0153] The storage modulus value of the adhesive layer 20 measured at 60° C. may be 0.01 MPa or more. The storage modulus value may be 0.05 MPa or more. The storage modulus value may be 0.1 MPa or more. The storage modulus value may be 5 MPa or less.

[0154] The storage modulus value of the adhesive layer 20 measured at 80° C. may be 0.001 MPa or more. The storage modulus value may be 0.003 MPa or more. The storage modulus value may be 0.01 MPa or less.

[0155] The storage modulus value of the adhesive layer 20 measured at 0° C. may be 5 MPa or more. The storage modulus value may be 10 MPa or more. The storage modulus value may be 20 MPa or more. The storage modulus value may be 25 MPa or more. The storage modulus value may be 200 MPa or less. The storage modulus value may be 180 MPa or less. The storage modulus value may be 150 MPa or less. The storage modulus value may be 120 MPa or less. The storage modulus value may be 100 MPa or less. The storage modulus value may be 80 MPa or less. The storage modulus value may be 50 MPa or less.

[0156] The storage modulus value of the adhesive layer 20 measured at -20°C may be 10 MPa or more. The storage modulus value may be 20 MPa or more. The storage modulus value may be 30 MPa or more. The storage modulus value may be 200 MPa or less. The storage modulus value may be 180 MPa or less. The storage modulus value may be 150 MPa or less. The storage modulus value may be 120 MPa or less. The storage modulus value may be 100 MPa or less. The storage modulus value may be 80 MPa or less.

[0157] The storage modulus value of the adhesive layer 20 measured at -40°C may be 20MPa or more. The storage modulus value may be 30MPa or more. The storage modulus value may be 40MPa or more. The storage modulus value may be 50MPa or more. The storage modulus value may be 300MPa or less. The storage modulus value may be 250MPa or less. The storage modulus value may be 200MPa or less. The storage modulus value may be 170MPa or less. The storage modulus value may be 150MPa or less. The storage modulus value may be 120MPa or less. The storage modulus value may be 100MPa or less.

[0158] The adhesive layer 20 may be a curable adhesive layer.

[0159] The storage modulus value of the adhesive layer 20 measured at 20° C. after curing may be 1 MPa or more. The storage modulus value may be 5 MPa or more. The storage modulus value may be 7 MPa or more. The storage modulus value may be 100 MPa or less. The storage modulus value may be 80 MPa or less. The storage modulus value may be 50 MPa or less. The storage modulus value may be 20 MPa or less.

[0160] The storage modulus value of the adhesive layer 20 measured at 40° C. after curing may be 0.1 MPa or more. The storage modulus value may be 0.5 MPa or more. The storage modulus value may be 1 MPa or more. The storage modulus value may be 2 MPa or more. The storage modulus value may be 30 MPa or less. The storage modulus value may be 20 MPa or less. The storage modulus value may be 10 MPa or less.

[0161] The storage modulus value of the adhesive layer 20 measured at 60° C. after curing may be 0.01 MPa or more. The storage modulus value may be 0.05 MPa or more. The storage modulus value may be 0.1 MPa or more. The storage modulus value may be 5 MPa or less.

[0162] The storage modulus value of the adhesive layer 20 measured at 80° C. after curing may be 0.001 MPa or more. The storage modulus value may be 0.003 MPa or more. The storage modulus value may be 0.01 MPa or less.

[0163] The storage modulus value measured at 0° C. after curing of the adhesive layer 20 may be 5 MPa or more. The storage modulus value may be 10 MPa or more. The storage modulus value may be 20 MPa or more. The storage modulus value may be 25 MPa or more. The storage modulus value may be 200 MPa or less. The storage modulus value may be 180 MPa or less. The storage modulus value may be 150 MPa or less. The storage modulus value may be 120 MPa or less. The storage modulus value may be 100 MPa or less. The storage modulus value may be 80 MPa or less. The storage modulus value may be 50 MPa or less.

[0164] The storage modulus value of the adhesive layer 20 measured at -20°C after curing may be 10 MPa or more. The storage modulus value may be 20 MPa or more. The storage modulus value may be 30 MPa or more. The storage modulus value may be 200 MPa or less. The storage modulus value may be 180 MPa or less. The storage modulus value may be 150 MPa or less. The storage modulus value may be 120 MPa or less. The storage modulus value may be 100 MPa or less. The storage modulus value may be 80 MPa or less.

[0165] The storage modulus value of the adhesive layer 20 measured at -40°C after curing may be 20MPa or more. The storage modulus value may be 30MPa or more. The storage modulus value may be 40MPa or more. The storage modulus value may be 50MPa or more. The storage modulus value may be 300MPa or less. The storage modulus value may be 250MPa or less. The storage modulus value may be 200MPa or less. The storage modulus value may be 170MPa or less. The storage modulus value may be 150MPa or less. The storage modulus value may be 120MPa or less. The storage modulus value may be 100MPa or less.

[0166] In this case, the bending characteristics of the adhesive layer can be controlled, thereby further improving the peeling resistance of the multilayer sheet.

[0167] The adhesive force of the adhesive layer 20 after curing may be 2N / inch or more. The adhesive force may be 2.5N / inch or more. The adhesive force may be 3N / inch or more. The adhesive force may be 3.5N / inch or more. The adhesive force may be 4N / inch or more. The adhesive force may be 4.5N / inch or more. The adhesive force may be 5N / inch or more. The adhesive force may be 5.5N / inch or more. The adhesive force may be 25N / inch or less. The adhesive force may be 22N / inch or less. The adhesive force may be 20N / inch or more. The adhesive force may be 18N / inch or more. The adhesive force may be 15N / inch or more. The adhesive force may be 12N / inch or more. The adhesive force may be 10N / inch or more. In this case, excellent adhesive force may be imparted to the multilayer sheet.

[0168] The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 0.8 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 0.9 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 1 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 1.2 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 1.5 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 1.8 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 2 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 2.3 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 2.5 N / inch or more. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 3.5 N / inch or less. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 3.2 N / inch or less. The adhesive force per unit thickness (1 μm) of the adhesive layer 20 after curing may be 3.0 N / inch or less. In this case, a relatively thin adhesive layer may be used, thereby helping to impart excellent bending properties to the multilayer film.

[0169] The description of the method for measuring the adhesive force of the adhesive layer 20 overlaps with the content of the method for measuring the adhesive force of the above-mentioned multilayer sheet, and therefore, the description thereof is omitted.

[0170] The total light transmittance (light transmittance) of the adhesive layer 20 according to ISO 13468 may be 85% or more. The light transmittance may be 88% or more. The light transmittance may be 89% or more. The light transmittance may be 99% or less.

[0171] The haze of the adhesive layer 20 may be 3% or less. The haze may be 2% or less. The haze may be 1.5% or less. The haze may be 1% or less. The haze may be greater than 0%.

[0172] The yellow index (YI) of the adhesive layer 20 may be 3 or less. The yellow index may be 2.8 or less. The yellow index may be 2.2 or less. The yellow index may be 1.0 or less. The yellow index may be 0.8 or less. The yellow index may be 0.5 or less. The yellow index may be greater than 0.

[0173] Such an adhesive layer is suitable for use in the display field due to its excellent optical properties.

[0174] The adhesive layer 20 may be an acrylic adhesive layer, a polyurethane adhesive layer or a silicone adhesive layer, and specifically, a silicone adhesive layer may be used. If a silicone adhesive layer is used, an adhesive layer having high light transmittance, heat resistance, weather resistance, etc. may be provided. In particular, the adhesive layer of the example described later has strong adhesive force even when the thickness is thin, thereby further improving the physical properties of the multilayer sheet compared to conventional optically clear adhesives (OCA, optically clear adhesives) such as acrylic adhesive layers.

[0175] The adhesive layer 20 may have a high adhesive force.

[0176] In order to maintain the physical properties of the multilayer sheet well even during repeated bending or folding, not only the performance of the transparent layer or coating 40 needs to be improved, but also the performance of the adhesive layer used to fix them and inhibit delamination needs to be improved. The inventors can use a silicone adhesive layer to obtain such improved performance.

[0177] The silicon-based adhesive layer can be obtained by applying the silicon adhesive composition and then drying and / or curing it.

[0178] The silicon bonding composition may include a silicon bonding agent, a catalyst and a solvent.

[0179] As the silicone adhesive, a commercially available silicone adhesive that can be used for optics can be applied. Specifically, a peroxide curing silicone adhesive and an addition reaction silicone adhesive can be applied.

[0180] As the peroxide-curing silicone adhesive, for example, KR-100, KR-101-10, and KR-130 manufactured by Shin-Etsu Chemical, DOWSIL SH 4280 manufactured by Dow Chemical, and SilGrip PSA 510 manufactured by Momentive Performance Materials can be used.

[0181] Illustratively, the addition reaction type silicone adhesive may be KR-3700, KR-3701, X-40-3237, X-40-3240, X-40-3291-1 manufactured by Shin-Etsu Chemical; DOWSIL SD4580, DOWSIL 4584, DOWSIL 4585, and DOWSIL 4587L manufactured by Dow Chemical; and SilGrip TSR1512 and TSR1516 manufactured by Momentive Performance Materials.

[0182] The use of an addition reaction type silicone adhesive is more advantageous in terms of process convenience.

[0183] The example can also include silicon MQ resin to improve the adhesion of the silicon-based adhesive layer. Wherein, silicon MQ resin is a polymer having at least 2 or more methyl groups in the siloxane skeleton in a cage-like oligosiloxane represented by the general formula RnSiXmOy. In the general formula, R can be an alkyl group with 1 to 5 carbon atoms, wherein at least 2 methyl groups are included. In the general formula, X is hydrogen, hydroxyl, chloride group or alkoxy group with 1 to 5 carbon atoms. In the general formula, n, m, and y are integers of 2 to 200, respectively. Specifically, the M unit (mono-terminated siloxane units) represented by R1R2X3SiO1 / 2 and the Q unit (tetra-terminated siloxane units) represented by SiO4 / 2 can be included. The weight average molecular weight can be 2000g / mol to 8000g / mol. If silicon MQ resin is applied to the adhesive layer, the adhesion can be further improved, especially, the initial adhesion can be improved.

[0184] Based on 100 parts by weight of the silicon adhesive, the silicon adhesive composition may include more than 5 parts by weight, more than 8 parts by weight, more than 10 parts by weight, or more than 20 parts by weight of the silicon MQ resin. Based on 100 parts by weight of the silicon adhesive, the silicon adhesive composition may include less than 70 parts by weight, less than 60 parts by weight, or less than 50 parts by weight of the silicon MQ resin. When the silicon adhesive and the silicon MQ resin are used together in such a ratio, even if the adhesive layer has a relatively thin thickness, it can have excellent adhesion.

[0185] For example, the silicone MQ resin may be X-92-128 and X-41-3003 manufactured by Shin-Etsu Chemical, or SilGrip SR545 and SilGrip SR1000 manufactured by Momentive Performance Materials.

[0186] The catalyst may be a platinum catalyst. For example, a product such as CATPL-50T of Shin-Etsu Chemical may be used. Even if a transparent film or substrate having heat-sensitive properties due to a shortened curing time is used, the catalyst can effectively form an adhesive layer without substantially damaging the substrate.

[0187] The silicon adhesive composition may include 0.5 to 2 parts by weight or 0.8 to 1.5 parts by weight of the catalyst based on 100 parts by weight of the silicon adhesive. In this case, the catalyst may effectively promote the curing reaction in the composition.

[0188] The silicon adhesive composition may further include a solvent. The solvent may dilute the silicon adhesive composition and impart fluidity to the composition, thereby making the operability such as coating favorable. In addition, it may help to form a relatively thin adhesive layer with excellent overall physical properties. Exemplarily, the solvent may be toluene, but may also be used without limitation within the range that does not damage the physical properties of the silicon adhesive composition.

[0189] Illustratively, the silicon bonding composition may include 20 to 45 weight percent of silicon bonding agent, 2 to 25 weight percent of silicon MQ resin, 0.2 to 0.5 weight percent of catalyst, and 50 to 70 weight percent of solvent.

[0190] The silicone adhesive composition can be applied to the elastic layer 10 to form the silicone curable adhesive layer 20. The silicone adhesive composition can be formed by coating on one surface of an additional substrate film (not shown) and then laminating on the elastic layer 10. However, depending on the order of the process, drying and curing can be performed either after coating or in separate processes. The silicone adhesive composition is formed into a thin layer by coating, and the layer is dried and included in the adhesive layer in a state before being completely cured by heat or light. In this way, the dried layer of the silicone adhesive composition before curing is called a precursor layer of the silicone curable adhesive layer.

[0191] The precursor layer may be cured by heat or light to form the adhesive layer 20. For example, the adhesive layer 20 may be formed by placing the precursor layer in contact with the surface to be bonded and thermally curing the surface at 90°C to 130°C for 1 minute to 5 minutes.

[0192] Adhesive layer 20 may include silicon adhesive derived repeating units and silicon MQ resin derived repeating units. Based on 100 parts by weight of silicon adhesive derived repeating units, adhesive layer 20 may include more than 5 parts by weight, more than 8 parts by weight, more than 10 parts by weight, more than 20 parts by weight, more than 30 parts by weight, or more than 40 parts by weight of silicon MQ resin derived repeating units. Based on 100 parts by weight of silicon adhesive derived repeating units, adhesive layer 20 may include less than 90 parts by weight, less than 80 parts by weight, less than 70 parts by weight, or less than 60 parts by weight of silicon MQ resin derived repeating units. In this case, the adhesive layer may have a thin thickness, and excellent optical properties and adhesion may be obtained.

[0193] The adhesive layer 20 may contain 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, or 0.5 parts by weight or more of the catalyst relative to 100 parts by weight of the silicon adhesive-derived repeating unit and the silicon MQ resin-derived repeating unit. The adhesive layer 20 may contain 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, or 2 parts by weight or less of the catalyst relative to 100 parts by weight of the silicon adhesive-derived repeating unit and the silicon MQ resin-derived repeating unit. In this case, the efficiency of the curing process for the precursor layer can be effectively improved.

[0194] The thickness of the adhesive layer 20 may be greater than 1 μm. The thickness may be greater than 1.5 μm. The thickness may be greater than 1.8 μm. The thickness may be greater than 2 μm. The thickness may be greater than 2.5 μm. The thickness may be greater than 3 μm. The thickness may be greater than 3.5 μm. The thickness may be less than 20 μm. The thickness may be less than 10 μm. The thickness may be less than 8 μm. The thickness may be less than 7 μm. In this case, an excellent adhesive effect may be obtained.

[0195] Other layers

[0196] Transparent layer

[0197] The transparent layer 30 may be used as a base layer for the coating layer 40 .

[0198] The total light transmittance (light transmittance) of the transparent layer 30 according to ISO 13468 may be 85% or more. The light transmittance may be 88% or more, 89% or more, or 99% or less. However, the light transmittance is not limited thereto as long as it can be used as a support layer of a display cover film.

[0199] The haze of the transparent layer 30 may be 3% or less. The haze may be 2% or less, 1.5% or less, or 1% or less. The haze may be greater than 0%. In this case, the multilayer sheet may be made more transparent.

[0200] The yellow index (YI) of the transparent layer 30 may be less than 3. For example, the yellow index may be less than 3, less than 2.8, less than 2.2, less than 1.0, less than 0.8 or less than 0.5. Furthermore, the yellow index may be greater than 0.

[0201] The transparent layer 30 may have excellent retardation characteristics. The in-plane retardation of the transparent layer 30 may be less than 600 nm, less than 500 nm, less than 400 nm, less than 300 nm, or less than 200 nm. The in-plane retardation of the transparent layer 30 may be greater than 0 nm, greater than 10 nm, greater than 30 nm, or greater than 50 nm. In this case, when a multilayer sheet is applied to the front surface of the display, the possibility of rainbow spots at the viewing angle can be effectively reduced, and the transparent layer can have stable mechanical properties.

[0202] The minimum in-plane phase difference of the transparent layer 30 may be 200 nm or less or 150 nm or less. Specifically, the minimum in-plane phase difference may be 120 nm or less, 100 nm or less, 85 nm or less, 75 nm or less, or 65 nm or less.

[0203] The transparent layer 30 may have a thickness direction phase difference of 4000 nm or more, 5000 nm or more, or 5500 nm or more. The transparent layer 30 may have a maximum thickness direction phase difference (Rthmax) of 6000 nm or more, 6500 nm or more, 7500 nm or more, 8000 nm or more, or 8500 nm or more.

[0204] In the transparent layer 30, the ratio of the thickness direction phase difference to the in-plane phase difference may be greater than 10, greater than 15, or greater than 20. The smaller the in-plane phase difference and the greater the thickness direction phase difference, the more advantageous it is for preventing the occurrence of rainbow spots. Therefore, it is better to maintain the ratio of the two values ​​as large as possible.

[0205] In the transparent layer 30 , the ratio of the maximum thickness direction phase difference to the minimum in-plane phase difference may be 30 or more, 40 or more, 50 or more, or 60 or more.

[0206] Since the molecular orientation is large and crystallization is promoted, the transparent layer having the above characteristics can have mechanical properties above an appropriate level. In addition, the transparent layer can effectively suppress the possibility of rainbow spots.

[0207] The phase difference is based on a value measured in a transparent layer having a thickness of 40 μm to 50 μm.

[0208] The tensile strength of the transparent layer 30 may be 15 kgf / mm 2 The tensile strength can be 18kgf / mm 2 Above, 20kgf / mm2 Above, 21kgf / mm 2 Above or 22kgf / mm 2 above.

[0209] The elongation of the transparent layer 30 may be greater than 15%, greater than 16%, greater than 17%, or greater than 17.5%.

[0210] The modulus of the transparent layer 30 may be 2.5 GPa or more. The modulus may be 3 GPa or more, 3.5 GPa or more, 3.8 GPa or more, or 4.0 GPa or more. The modulus may be 10 GPa or less, or 8 GPa or less.

[0211] The compressive strength of the transparent layer 30 may be 0.4 kgf / μm or more. The compressive strength may be 0.45 kgf / μm or more or 0.46 kgf / μm or more.

[0212] As the transparent layer 30 , a polyester film, a polyimide film, a polyamide film, or a polyimide-amide film can be suitably used.

[0213] The transparent layer 30 may be a polyester film, and the polyester film may include a polyester resin.

[0214] The polyester resin may be a homopolymer resin or a copolymer resin obtained by polycondensation of dicarboxylic acid and diol. The polyester resin may be a mixed resin obtained by mixing the homopolymer resin or the copolymer resin.

[0215] Examples of dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, diphenyl carboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl sulfone carboxylic acid, anthracene dicarboxylic acid, 1,3-cyclopentane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, hexanoic acid, 2-methylhexanoic acid, trimethylhexanoic acid, pimelic acid, succinic acid, sebacic acid, platinoic acid, and dodecyl carboxylic acid.

[0216] Examples of the diol include ethylene glycol, propylene glycol, hexylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-bis(4-hydroxyphenyl)propane, and bis(4-hydroxyphenyl)sulfone.

[0217] Preferably, the polyester resin may be an aromatic polyester resin having excellent crystallinity, for example, a polyethylene terephthalate (PET) resin may be used as a main component.

[0218] When the transparent layer 30 is a polyester film, the transparent layer 30 may contain 85 weight percent or more, 90 weight percent or more, 95 weight percent or more, or 99 weight percent or more of the polyester resin.

[0219] In addition to the PET resin, the polyester film may also include other polyester resins. Specifically, the polyester film may also include less than about 15 weight percent of polyethylene naphthalate (PEN) resin. More specifically, the polyester film may also include about 0.1 weight percent to 10 weight percent or about 0.1 weight percent to 5 weight percent of PEN resin.

[0220] In the manufacturing process such as heating and stretching, the degree of crystallinity of the polyester film having such a composition can be increased, and the mechanical properties such as tensile strength can be improved.

[0221] The transparent layer 30 may further contain a filler in addition to the polyester-based resin.

[0222] The filler may be one or more selected from the group consisting of barium sulfate, silicon dioxide, and calcium carbonate. The transparent layer 30 includes the filler to have controlled illuminance characteristics and improve windability. In addition, when a film is produced, the driveability and scratch improvement effect can be improved.

[0223] The particle size of the filler may be 0.01 μm or more and less than 1.0 μm. The particle size of the filler may be 0.05 μm to 0.9 μm or 0.1 μm to 0.8 μm, but is not limited thereto.

[0224] The transparent layer 30 may contain 0.01 to 3 weight percent of filler based on the total weight of the transparent layer 30. The transparent layer 30 may contain 0.05 to 2.5 weight percent, 0.1 to 2 weight percent, or 0.2 to 1.7 weight percent of filler based on the total weight of the transparent layer 30, but is not limited thereto.

[0225] The thickness of the transparent layer 30 may be 15 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 55 μm or more, 65 μm or more, or 75 μm or more, and may be 500 μm or less, 400 μm or less, 300 μm or less, 200 μm or less, 120 μm or less, 95 μm or less, or 85 μm or less. As a specific example, the thickness of the transparent layer 30 may be 15 μm to 120 μm, more specifically, 20 μm to 95 μm or 25 μm to 85 μm. A transparent layer having such a thickness may not only obtain sufficient mechanical properties, but also obtain excellent optical properties.

[0226] As the transparent layer 30, SH33 / 34 products, SH37 / 38 products, TF110 products, V7610 products, V5400 products, V7611 products, TU94 products, TU63A products, TOF50 products, etc., which are currently marketed by SKC, can be used, but are not limited to these.

[0227] The manufacturing method of the transparent layer is based on a common film manufacturing method. For example, the polyester film can be manufactured by a method comprising the following steps: step 1, extruding a composition comprising a polyester resin to obtain an unstretched film; step 2, stretching the unstretched film in the length direction and the width direction; and step 3, heat fixing the stretched film.

[0228] In the manufacturing method, the raw material resin is extruded, and then preheated, stretched, and heat-fixed to produce an unstretched film. The extrusion may be performed at a temperature of 230°C to 300°C or 250°C to 280°C.

[0229] The unstretched film is preheated at a certain temperature before being stretched. Based on the glass transition temperature (Tg) of the polyester resin, the preheating temperature ranges from Tg+5°C to Tg+50°C, and can be determined to meet the range of 70°C to 90°C. When within the range, not only can the flexibility of the unstretched film be ensured to facilitate stretching, but also the breakage phenomenon during the stretching process can be effectively prevented.

[0230] Stretching is performed by biaxial stretching, for example, by simultaneous biaxial stretching or differential biaxial stretching to stretch in two axes in the width direction (tensor direction, TD) and the length direction (machine direction, MD). Preferably, differential biaxial stretching can be performed in which stretching is first performed in one direction and then in a direction perpendicular to the direction.

[0231] The length direction stretching ratio can be 2.0 times to 5.0 times, more specifically, 2.8 times to 3.5 times. And, the width direction stretching ratio can be 2.0 times to 5.0 times, more specifically, 2.9 times to 3.7 times. Preferably, the length direction stretching ratio d1 is similar to the width direction stretching ratio d2, specifically, the ratio (d2 / d1) of the length direction stretching ratio d2 relative to the width direction stretching ratio d1 can be 0.5 to 1.0, 0.7 to 1.0 or 0.9 to 1.0. When the length before stretching is set to 1.0, the stretching ratios d1 and d2 are the ratios of the lengths after stretching. And, the stretching speed can be 6.5m / min to 8.5m / min, but is not particularly limited.

[0232] The stretched sheet may be heat-fixed at 150° C. to 250° C., more specifically, 160° C. to 230° C. The heat-fixing may be performed for 5 seconds to 1 minute, more specifically, for 10 seconds to 45 seconds.

[0233] After the heat setting is started, the film may be relaxed in the length direction and / or the width direction, and the temperature may range from 150°C to 250°C.

[0234] coating

[0235] The coating layer 40 may include at least one coating material selected from the group consisting of an organic component, an inorganic component, and an organic-inorganic composite component.

[0236] The coating material may include an organic resin. Specifically, the organic resin may be a curable resin or a binder resin.

[0237] The coating 40 may be a curable coating.

[0238] The coating layer 40 may include at least one compound selected from the group consisting of polyurethane acrylate compounds, acrylate compounds, acrylic acid compounds, and epoxy acrylate compounds, or a cured product of the compounds.

[0239] The urethane acrylate-based compound may include a urethane bond as a repeating unit, and may have a plurality of functional groups.

[0240] The polyurethane acrylate compound may be a polyurethane compound formed by the reaction of a diisocyanate compound and a polyol, wherein the terminal of the polyurethane compound is substituted with an acrylate group.

[0241] The diisocyanate compound may include at least one of a linear, branched or cyclic aliphatic diisocyanate compound having 4 to 12 carbon atoms and an aromatic diisocyanate compound having 6 to 20 carbon atoms.

[0242] The polyol may contain 2 to 4 hydroxyl groups (-OH) and may be a linear, branched or cyclic aliphatic polyol compound having 4 to 12 carbon atoms or an aromatic polyol compound having 6 to 20 carbon atoms. The substitution based on the terminal of the acrylate group may be performed by an acrylic compound having a functional group capable of reacting with an isocyanate group (-NCO). For example, an acrylic compound having a hydroxyl group, an amine group, etc. may be used, and a hydroxyalkyl acrylate or an amino alkyl acrylate having 2 to 10 carbon atoms may be used.

[0243] The polyurethane acrylate compound may contain 2 to 15 functional groups.

[0244] Examples of polyurethane acrylate compounds include difunctional polyurethane acrylate oligomers with a weight average molecular weight of 1400 to 25000, trifunctional polyurethane acrylate oligomers with a weight average molecular weight of 1700 to 16000, tetrafunctional polyurethane acrylate oligomers with a weight average molecular weight of 500 to 2000, hexafunctional polyurethane acrylate oligomers with a weight average molecular weight of 818 to 2600, nonafunctional polyurethane acrylate oligomers with a weight average molecular weight of 2500 to 5500, decafunctional polyurethane acrylate oligomers with a weight average molecular weight of 3200 to 3900, pentafunctional polyurethane acrylate oligomers with a weight average molecular weight of 2300 to 20000, etc., but are not limited thereto.

[0245] The glass transition temperature (Tg) of the polyurethane acrylate compound may be -80°C to 100°C, -80°C to 90°C, -80°C to 80°C, -80°C to 70°C, -80°C to 60°C, -70°C to 100°C, -70°C to 90°C, -70°C to 80°C, -70°C to 70°C, -70°C to 60°C, -60°C to 100°C, -60°C to 90°C, -60°C to 80°C, -60°C to 70°C, -60°C to 60°C, -50°C to 100°C, -50°C to 90°C, -50°C to 80°C, -50°C to 70°C or -50°C to 60°C.

[0246] The acrylate compound may be one or more selected from the group consisting of substituted or unsubstituted methyl acrylate and substituted or unsubstituted methacrylate. The acrylate compound may include 1 to 10 functional groups.

[0247] Examples of acrylate compounds include, but are not limited to, trimethylolpropane triacrylate (TMPTA), ethoxylated trimethylolpropane triacrylate (TMPEOTA), propoxylated glycerol triacrylate (GPTA), pentaerythritol tetraacrylate (PETA), and dipentaerythritol hexaacrylate (DPHA).

[0248] The weight average molecular weight of the acrylic acid ester compound may be 500 to 6,000, 500 to 5,000, 500 to 4,000, 1,000 to 6,000, 1,000 to 5,000, 1,000 to 4,000, 1,500 to 6,000, 1,500 to 5,000, or 1,500 to 4,000.

[0249] The methyl acrylate equivalent of the acrylic ester compound may be 50 g / eq to 300 g / eq, 50 g / eq to 200 g / eq, or 50 g / eq to 150 g / eq.

[0250] The acrylic compound may contain 1 to 10 functional groups. Examples of the acrylic compound include monofunctional methyl acrylate oligomers having a weight average molecular weight of 100 to 300, difunctional methyl acrylate oligomers having a weight average molecular weight of 250 to 2000, and epoxy methyl acrylate oligomers having a weight average molecular weight of 1000 to 3000.

[0251] The epoxy acrylate compound may contain 1 to 10 functional groups. Examples of the epoxy acrylate compound include, but are not limited to, a monofunctional epoxy acrylate oligomer having a weight average molecular weight of 100 to 300, a difunctional epoxy acrylate oligomer having a weight average molecular weight of 250 to 2000, or a tetrafunctional epoxy acrylate oligomer having a weight average molecular weight of 1000 to 3000. The epoxy equivalent of the epoxy acrylate compound may be 50 g / eq to 300 g / eq, 50 g / eq to 200 g / eq, or 50 g / eq to 150 g / eq.

[0252] Based on the total weight of the coating 40 , the content of the organic resin may be 30 weight percent to 100 weight percent, 40 weight percent to 90 weight percent, or 50 weight percent to 80 weight percent.

[0253] The coating layer 40 may not contain inorganic fillers such as silicon dioxide. In this case, the bonding force between the transparent film layer and the coating layer 40 of the above composition can be improved.

[0254] The coating 40 may also optionally contain a filler.

[0255] For example, the filler may be inorganic particles. Examples of the filler include silicon dioxide, barium sulfate, zinc oxide, and aluminum oxide.

[0256] The particle diameter of the filler may be 1 nm to 100 nm. The particle diameter of the filler may be 5 nm to 50 nm or 10 nm to 30 nm.

[0257] The filler may include inorganic fillers having different particle size distributions. The filler may include a first inorganic filler having a D50 of 20 nm to 35 nm and a second inorganic filler having a D50 of 40 nm to 130 nm.

[0258] Based on the total weight of the coating 40, the content of the filler may be greater than 25 weight percent, greater than 30 weight percent, or greater than 35 weight percent. Also, based on the total weight of the coating 40, the content of the filler may be less than 50 weight percent, less than 45 weight percent, or less than 40 weight percent.

[0259] In this case, the mechanical properties of the filler can be improved.

[0260] The coating 40 may further include a photoinitiator or a reactant thereof. The photoinitiator or the like may cause a curing reaction of the coating 40 .

[0261] Examples of photoinitiators include 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, methyl toluate, α,α-dimethoxy-α-acetophenone, 2-benzoyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylphenyl)-phosphine oxide or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, but are not limited thereto. Commercially available products include Irgacure 184, Irgacure 500, Irgacure 651, Irgacure 369, Irgacure 907, Darocur 1173, Darocur MBF, Irgacure 819, Darocur TPO, Irgacure 907, and Esacure KIP 100F. The photoinitiator may be used alone or in combination of two or more different types.

[0262] The coating 40 may further include an antifouling agent. The coating 40 may include a fluorine compound as an antifouling agent. The fluorine compound may have an antifouling function. Specifically, the fluorine compound may be an acrylic compound having a perfluoroalkyl group, and as a specific example, perfluorohexylethyl methacrylate may be cited, but is not limited thereto.

[0263] The coating 40 may further include an antistatic agent. The antistatic agent may include an ionic surfactant. For example, the ionic surfactant may include an ammonium salt or a quaternary alkylammonium salt, and the ammonium salt and the quaternary alkylammonium salt may include a halide such as chloride or bromide.

[0264] The coating 40 may also include additives such as surfactants, UV absorbers, UV stabilizers, anti-yellowing agents, leveling agents, or dyes for improving color values. For example, the surfactant may be a 1-2 functional fluorine-based methyl acrylate, a fluorine-based surfactant, or a silicon-based surfactant. The surfactant may be included in a form dispersed or cross-linked in the coating 40. In addition, as the UV absorber, benzophenone compounds, benzotriazole compounds, or triazine compounds may be cited, and as the UV stabilizer, tetramethyl piperidine may be cited. The content of these additives may be adjusted in various ways without reducing the physical properties of the coating 40. For example, based on the entire coating 40, the content of the additive may be 0.01 weight percent to 10 weight percent, but is not limited thereto.

[0265] The coating layer 40 may be composed of a single layer or two or more layers.

[0266] The coating layer 40 may be formed as a single layer, thereby increasing the surface durability of the multi-layer sheet and simultaneously performing an anti-fingerprint or anti-fouling function.

[0267] The thickness of the coating layer 40 may be 2 μm or more, 3 μm or more, 5 μm or more, or 7 μm or more, and may be 50 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less. In the case of such a thickness, not only can it be applied with a thin thickness, but also durability such as surface hardness above an appropriate level can be given to the multilayer sheet, and the overall flexibility of the multilayer sheet can be maintained.

[0268] The coating layer 40 may be formed by a coating layer manufacturing method.

[0269] The method for producing a coating layer may include a step of curing the coating layer composition after coating.

[0270] The composition for producing a coating layer may contain at least one of an organic resin composition, an inorganic resin composition, and an organic-inorganic composite composition.

[0271] The composition for producing a coating layer may contain at least one of an acrylic compound, a siloxane compound, or a silsesquioxane compound, and may further contain inorganic particles.

[0272] The coating production composition may contain a urethane acrylate compound, an acrylate compound, and a fluorine compound as a specific example.

[0273] Furthermore, the coating composition may further contain a photoinitiator, an antifouling additive, an antistatic agent, other additives and / or an organic solvent as required.

[0274] As the organic solvent, alcohol solvents such as methanol, ethanol, isopropanol, and butanol can be used alone or in combination; alcohol solvents such as 2-methoxyethanol, 2-ethoxyethanol, and 1-methoxy-2-propanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetone, and cyclohexanone; ether solvents such as propylene glycol monopropyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, and diethylene glycol-2-ethylhexyl ether; aromatic solvents such as benzene, toluene, and xylene, etc. can be used.

[0275] The content of the organic solvent can be adjusted in various ways within the range that does not reduce the physical properties of the coating, and therefore, is not particularly limited. However, among the components contained in the composition for producing the coating, the weight ratio of the solid component to the organic solvent can be about 1:1 to 250 based on the solid component. When the organic solvent is within the above range, it can have appropriate fluidity and coating properties.

[0276] The coating composition may include 10 to 30 weight percent of an organic resin, 0.1 to 5 weight percent of a photoinitiator, 0.01 to 2 weight percent of an antifouling additive, 0.1 to 10 weight percent of an antistatic agent, and the remainder an organic solvent.

[0277] In the case of the above-mentioned composition, the mechanical properties as well as the antifouling and antistatic properties of the coating can be improved at the same time.

[0278] The composition for coating production can be applied to a transparent film by a common coating method and then cured. The coating method can be a rod coating method, a blade coating method, a roller coating method, a doctor blade coating method, a die coating method, a micro-gravure coating method, a comma coating method, a slot die coating method, a lip coating method, or a solution casting method.

[0279] The drying and curing steps of the applied coating composition may be performed sequentially or simultaneously.

[0280] Drying is a process of removing organic solvent from the applied coating composition. Drying can be performed at a temperature of 40°C to 100°C, preferably 40°C to 80°C, 50°C to 100°C, or 50°C to 80°C, and can be performed for about 1 minute to 20 minutes, preferably 1 minute to 10 minutes or 1 minute to 5 minutes.

[0281] Curing is a process of inducing a chemical reaction in the coating composition to form a coating film. Depending on the resin used in the coating composition, etc., an appropriate photocuring and / or thermal curing method can be used.

[0282] Base material layer

[0283] The multilayer sheet 100 may further include a base layer (not shown) disposed on the adhesive layer 20 .

[0284] The base layer may be disposed on the adhesive layer 20 so as to be in contact with the adhesive layer 20. When another layer is disposed between the base layer and the adhesive layer 20, the base layer may be disposed on the adhesive layer 20 so as not to be in contact with the adhesive layer 20.

[0285] As long as it is a resin commonly used in the field of substrate films, the raw material of the substrate layer is not limited. Illustratively, the substrate layer may include at least one of a polyester resin, a polyimide resin, and a polyether block amide resin. In particular, one of a polyester film, a polyimide film, and a polyether block amide film may be used as the substrate layer. The polyester film may be a polyethylene terephthalate (PET) film.

[0286] The multilayer sheet 100 may include two or more base material layers. In this case, the multilayer sheet 100 may have a structure in which the base material layers and the adhesive layers 20 are cross-laminated.

[0287] Method for manufacturing multilayer sheet

[0288] A method for manufacturing a multilayer sheet according to another embodiment of the present specification may include: a step of manufacturing an elastic layer; and a step of laminating an adhesive layer on the elastic layer.

[0289] The step of laminating the adhesive layer on the elastic layer may include coating the elastic layer with a silicone adhesive composition and drying the composition to form a precursor layer. The step of laminating the adhesive layer on the elastic layer may include curing the precursor layer to form the adhesive layer.

[0290] When the multilayer sheet includes two or more adhesive layers and has a structure in which elastic layers and adhesive layers are cross-laminated, the method for producing the multilayer sheet may further include the step of laminating a pre-fabricated elastic layer on the adhesive layer.

[0291] If necessary, the method for producing a multilayer sheet may further include the step of disposing a transparent layer on the adhesive layer, and may further include the step of forming a coating layer on the transparent layer.

[0292] If necessary, the method for producing the multilayer sheet may further include the step of disposing a release film on the adhesive layer.

[0293] The description of the method of forming each layer overlaps with the above content, so the description is omitted.

[0294] Multilayer electronic devices

[0295] Figure 5 FIG. 1 is a conceptual diagram for explaining a multilayer electronic device according to another embodiment of the present specification. Figure 5 Describe the example.

[0296] A multilayer electronic device 200 according to another embodiment of the present specification includes: a multilayer sheet 100 , and a light-emitting functional layer 15 disposed below the multilayer sheet 100 .

[0297] The multilayer sheet 100 may be used as a cover layer of a multilayer electronic device 200 .

[0298] The description of the multilayer sheet 100 overlaps with the above description, and therefore, the description thereof will be omitted.

[0299] Illustratively, the multilayer electronic device 200 may be a display device, for example, a large-area display device, a foldable display device, a bendable display device, or a flexible display device, and may be a bendable mobile communication device (such as a mobile phone) or a bendable laptop computer.

[0300] The light-emitting functional layer 150 includes a light-emitting layer (not shown).

[0301] The light-emitting layer includes an element that releases light in a display device according to a signal. Exemplarily, the light-emitting layer may include: a signal transmission layer for transmitting an external electrical signal to a color-emitting layer; a color-emitting layer, which is arranged on the signal transmission layer and emits color according to the provided signal; and a packaging layer for protecting the color-emitting layer. The signal transmission layer may include a thin film transistor (TFT), which may be LTPS, a-SiTFT or Oxide TFT, but is not limited thereto. The packaging layer may be Thin Film Encapsulation (TFE), but is not limited thereto.

[0302] The light emitting layer may be disposed on a support layer (not shown). The support layer may be a layer having insulating properties and heat resistance properties, and for example, a polyimide film, a glass layer, a PET film, etc. may be used.

[0303] The light emitting functional layer 150 may further include a sensing layer (not shown), and a touch sensor or the like may be used as the sensing layer.

[0304] The light-emitting functional layer 150 may further include a polarizing layer (not shown). The polarizing layer may be disposed on the light-emitting layer or on the sensing layer.

[0305] Hereinafter, specific embodiments are described in further detail.

[0306] Manufacturing Example: Manufacturing of Multilayer Sheet

[0307] Embodiment: According to different embodiments, the elastic layer is manufactured by using PEBA resin products of Arkema. Specifically, the PEBA resin is placed in an extruder and melt-kneaded at about 220°C, and then extruded into a single layer to manufacture the elastic layer. The product names of the PEBA resins used in the manufacture of the elastic layer in different embodiments and the thickness of the elastic layer are recorded in Table 1 below.

[0308] The adhesive layer is formed on one surface and the other surface of the manufactured elastic layer. Specifically, the silicone adhesive composition is applied to one surface and the other surface of the elastic layer, and then dried and cured to form the adhesive layer. The drying and curing are performed at a temperature of 90° C. for 5 minutes.

[0309] The silicone adhesive composition uses a composition comprising 29.851 weight percent of Shin-Etsu's KR-3700 model as a silicone adhesive, 7.164 weight percent of Shin-Etsu's X-92-128 model as a silicone MQ resin, 0.299 weight percent of Shin-Etsu's CAT-PL-50T model as a platinum catalyst, and 62.686 weight percent of toluene.

[0310] The thickness of the adhesive layer formed on one surface and the other surface of the elastic layer, respectively, is applied in the same manner. Figures 6 to 11 The thickness of the adhesive layer applicable to different embodiments is described in .

[0311] Comparative Example 1: The silicon-based adhesive composition used in the embodiment was dried and cured to form an adhesive layer with a thickness of 10 μm.

[0312] Evaluation Example: Measurement of Storage Modulus Value Based on Temperature

[0313] The modulus was measured by dynamic mechanical analysis (DMA) of different embodiments and comparative examples. Specifically, the storage modulus of samples of different embodiments and comparative examples was measured in the range of -50°C to 100°C using the DMA7100 model of Hitachi. The heating rate was 5°C / min.

[0314] In the following Table 1, Table 2 and Figures 6 to 12 The measurement results at various measurement temperatures of different embodiments and comparative examples are presented.

[0315] Evaluation example: Measurement of RSM value based on temperature

[0316] The SM values ​​of the elastic layer and the adhesive layer of the multilayer sheets of Examples 2, 8, 14, 20, 26 and 32 at different temperatures were measured by the DMA7100 model of Hitachi. E Value, SM B The measurement temperature range was set to -50°C to 100°C, and the heating rate was 5°C / min. The SM values ​​at -40°C, -20°C, 0°C, 20°C, and 40°C were measured. E Value and SM B values, and the RSM value was calculated from the values.

[0317] The SM values ​​at various measurement temperatures of different embodiments are recorded in Tables 3 and 4 below. E Value, SM B Value and RSM value.

[0318] Evaluation example: Determination of adhesive strength of adhesive layers of different thicknesses

[0319] After the silicone adhesive composition of the embodiment applicable to different manufacturing examples was coated on a PET film (SKC, NRF grade), drying and curing were performed to obtain an adhesive layer. Drying and curing were performed at a temperature of 90° C. for 5 minutes. The thickness of the adhesive layer applicable to different manufacturing examples is recorded in Table 3 below.

[0320] Then, the adhesive strength of the adhesive layer formed in each manufacturing example was measured. The adhesive strength was measured in a T-Peel format using the QC-M1F UTM model of COMETECH, and the peeling speed was 300 mm / min.

[0321] The adhesion values ​​measured in the different manufacturing examples are presented in Table 5 below.

[0322] Table 1

[0323]

[0324]

[0325] Table 2

[0326]

[0327]

[0328] Table 3

[0329]

[0330] Table 4

[0331]

[0332] Table 5

[0333] Thickness of adhesive layer (μm) Adhesion strength (N / inch) Adhesion force per 1μm (N / inch) Production Example 1 1 0.32 0.32 Production Example 2 2 0.72 0.36 Production Example 3 3 5.59 1.86 Production Example 4 4 10.43 2.60 Production Example 5 5 12.70 2.54 Production Example 6 8 14.45 1.80 Production Example 7 10 14.60 1.46 Production Example 8 15 14.62 0.97

[0334] Although the preferred embodiments are described in detail above, the protection scope of the present invention is not limited thereto, and various modifications and improvements made by ordinary technicians using the basic concepts of the examples defined in the claims also fall within the protection scope of the present invention.

[0335] Description of Reference Numerals

[0336] 100: Multilayer

[0337] 10: Elastic layer

[0338] 20: Adhesive layer

[0339] 30: Transparent layer

[0340] 40: Coating

[0341] 50: Release film

[0342] 51: Release layer

[0343] 52: Release substrate layer

[0344] 150: Light-emitting functional layer

[0345] 200: Multilayer electronic device

Claims

1. A multilayer sheet, characterized in that: include: elastic layer, and An adhesive layer, disposed on the elastic layer; The storage modulus of the multilayer sheet measured at 20° C. is 10 MPa or more and 2000 MPa or less.

2. The multilayer sheet according to claim 1, characterized in that: The RSM value of the following formula 1 measured at 20° C. for the multilayer sheet is 1 or more and 200 or less: [Formula 1] RSM=SM E / SM B In the formula 1, The SM E is the storage modulus value of the elastic layer, The SM B is the storage modulus value of the adhesive layer.

3. The multilayer sheet according to claim 1, characterized in that: The absolute value of the value obtained by subtracting the storage modulus value measured at 60° C. from the storage modulus value measured at 20° C. of the multilayer sheet is 1000 MPa or less.

4. The multilayer sheet according to claim 1, characterized in that: The absolute value of the value obtained by subtracting the storage modulus value measured at 20° C. from the storage modulus value measured at −40° C. of the multilayer sheet is 1500 MPa or less.

5. The multilayer sheet according to claim 1, characterized in that: The storage modulus of the elastic layer measured at 20° C. is 10 MPa or more and 3000 MPa or less.

6. The multilayer sheet according to claim 1, characterized in that: The storage modulus of the adhesive layer measured at 20° C. is 1 MPa or more and 50 MPa or less.

7. The multilayer sheet according to claim 1, characterized in that: The adhesive force of the adhesive layer after curing is greater than 2 N / inch.

8. The multilayer sheet according to claim 1, characterized in that: The adhesive force per unit thickness of the adhesive layer after curing is greater than 0.8 N / inch, and the unit thickness is 1 μm.

9. A multilayer electronic device, characterized in that: include: The multilayer sheet according to claim 1; as well as The light-emitting functional layer is disposed below the multilayer sheet.

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