Laminate

Abstract

The present invention provides a laminate that exhibits high adhesion to alkali-free glass or chemically strengthened glass and is resistant to peeling. [Solution] The laminate 1 comprises an adhesive layer 2 and an adhesive layer 3 laminated on at least one surface of the adhesive layer 2. The total light transmittance of the laminate 1 is 85% or more. The ratio of the elastic modulus of the adhesive layer 3 at 25°C to the elastic modulus of the adhesive layer 2 at 25°C [elastic modulus of adhesive layer 3 at 25°C / elastic modulus of adhesive layer 2 at 25°C] is 2 or more. The ratio of the thickness of the adhesive layer 2 to the thickness of the adhesive layer 3 is preferably 1:0.0001 to 1:1.

Description

Technical Field

[0001] The present invention relates to a laminate.

Background Art

[0002] OLED (Organic light emitting diode) display devices have advantages in display performance such as high visibility, low viewing angle dependence, and fast response speed compared to liquid crystal display devices. In addition, since OLED display devices do not use a backlight, they are advantageous for thinning, and can also be used as a flexible and foldable device that can be curved or folded.

[0003] In an OLED display device, in order to impart functions such as surface protection and flexibility to the viewing side of the OLED element, layers of various optical elements such as a substrate such as plastic or thin glass and a hard coat layer are laminated via an adhesive layer.

[0004] In recent years, with the spread of foldable devices, optical products such as OLED display devices may be required to have a performance that does not cause peeling or lifting even when the bending / folding operation is repeated. Therefore, a highly bend-resistant adhesive sheet that can withstand bending operations at multiple locations has been proposed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In particular, foldable devices require even thinner designs to allow for easy bending. For such foldable devices, alkali-free glass or chemically strengthened glass with high flexibility are sometimes used as thin glass. However, conventional adhesive layers have poor adhesion to alkali-free glass and chemically strengthened glass. Therefore, when bonded to alkali-free glass or chemically strengthened glass and then bent, the adhesive layer fails to hold the glass, leading to a problem of peeling.

[0007] The present invention has been made in view of the above problems, and its object is to provide a laminate that has high adhesion to alkali-free glass or chemically strengthened glass and is less prone to peeling. [Means for solving the problem]

[0008] As a result of diligent research to achieve the above objective, the inventors of this invention have found that a particular laminate exhibits high adhesion to alkali-free glass and chemically strengthened glass, and is less prone to peeling.

[0009] The present invention is a laminate comprising an adhesive layer and an adhesive layer laminated on at least one surface of the adhesive layer. The total light transmittance of the above laminate is 85% or more. The present invention provides a laminate in which the ratio of the elastic modulus of the adhesive layer at 25°C to the elastic modulus of the adhesive layer at 25°C [elastic modulus of the adhesive layer at 25°C / elastic modulus of the adhesive layer at 25°C] is 2 or more.

[0010] The ratio of the thickness of the adhesive layer to the thickness of the bonding agent layer is preferably 1:0.0001 to 1:1.

[0011] It is preferable that the glass transition temperature of the adhesive layer is 0 to 180°C.

[0012] It is preferable that the difference between the glass transition temperature of the adhesive layer and the glass transition temperature of the tack layer [(glass transition temperature of the adhesive layer) - (glass transition temperature of the tack layer)] is 50 to 220°C.

[0013] The elastic modulus of the above adhesive layer at 25°C is 10 3 ~10 6 Pa is preferable.

[0014] The laminate of the present invention may have a release liner bonded to at least one surface of the laminate. [Effects of the Invention]

[0015] The laminate of the present invention exhibits high adhesion to alkali-free glass or chemically strengthened glass, making it less prone to peeling. Therefore, even when used laminated in a foldable device (particularly a foldable OLED display device), it is less likely to detach from the alkali-free glass or chemically strengthened glass, providing an aesthetically pleasing foldable device. [Brief explanation of the drawing]

[0016] [Figure 1] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 2] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 3] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 4] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 5] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 6] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 7] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 8] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 9]This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 10] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 11] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 12] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 13] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 14] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Figure 15] This is a cross-sectional view showing one embodiment of the laminate of the present invention. [Modes for carrying out the invention]

[0017] In this specification, "adhesion" refers to the property of two surfaces adhering tightly to each other based on cohesive forces derived from the chemical structure of the composition in response to external pressure (e.g., minute pressure), and being able to be separated if necessary. In contrast, "bonding" refers to the property of two surfaces being firmly joined by fluidization due to heating and subsequent solidification, curing, heating, pressurization, or two or more of these operations.

[0018] Furthermore, in this specification, the form of the "adhesive" is not particularly limited and may be liquid at room temperature (for example, a fluid solid (paste), an adhesive composition, etc.), or a solid at room temperature. Also, the form of the "adhesive" is not particularly limited and may be in the form of a sheet. In this specification, the "adhesive layer" is a non-fluid sheet-like (layered) adhesive layer.

[0019] [Laminated structure] The laminate of the present invention comprises at least an adhesive layer and an adhesive layer laminated on at least one surface of the adhesive layer. Furthermore, the total light transmittance of the laminate of the present invention is 85% or more.

[0020] Figures 1 to 7 show cross-sectional views of one embodiment of the laminate of the present invention. The laminate 1 shown in Figure 1 comprises an adhesive layer 2 and an adhesive layer 3. The adhesive layer 3 is formed on one surface of the adhesive layer 2 so as to be in contact with the adhesive layer 2. A compatible layer, described later, may also be formed at the interface between the adhesive layer 2 and the adhesive layer 3. If a compatible layer is formed, the adhesive layer 2 and the adhesive layer 3 are considered to be in contact. The shape of the adhesive layer 3 is not particularly limited, but for example, it may be in the form of a sheet, similar to the adhesive layer 2, or it may be formed over the entire surface of one surface of the adhesive layer 2, or it may be in a shape (annular, frame-like) that covers a part of one surface of the adhesive layer 2.

[0021] The elastic modulus of adhesive layer 2 at 25°C is lower than that of adhesive layer 3 at 25°C. In other words, the elastic modulus of adhesive layer 3 at 25°C is higher than that of adhesive layer 2 at 25°C. Specifically, the ratio of the elastic modulus of adhesive layer 3 at 25°C to the elastic modulus of adhesive layer 2 at 25°C [elastic modulus of adhesive layer at 25°C / elastic modulus of adhesive layer at 25°C] is 2 or greater. By having adhesive layer 2 and adhesive layer 3 with different elastic moduli in this way, the adhesive layer 2 with the lower elastic modulus can flexibly follow bending and folding movements, while the adhesive layer 3 with the higher elastic modulus can adhere strongly to alkali-free glass or chemically strengthened glass. Therefore, it is possible to achieve both excellent flexibility and excellent adhesion to alkali-free glass and chemically strengthened glass. Furthermore, since the laminate 1 has a total light transmittance of 85% or more, when used in optical products such as OLED display devices, it does not obstruct the light emitted from the display device and can ensure brightness.

[0022] In the laminate of the present invention, the adhesive layer only needs to be laminated on at least one surface of the adhesive layer. In this case, as shown in Figure 1, the adhesive layer 3 may be laminated over the entire surface of one surface of the adhesive layer 2, or it may be laminated over a part of one surface.

[0023] The laminate of the present invention may comprise multiple adhesive layers. For example, the laminate of the present invention comprises at least one adhesive layer on one side of the adhesive layer, but may also comprise an adhesive layer on the side of the adhesive layer opposite to the aforementioned side (the other side). The multiple adhesive layers may have the same thickness, composition, shape, or physical properties, or they may be different layers.

[0024] The laminate 1 shown in Figure 2 comprises a plurality of adhesive layers 3, with adhesive layers 3 comprising adhesive layer 31 and adhesive layer 32. In the laminate 1 shown in Figure 2, adhesive layer 31 is formed over the entire surface of one side of the adhesive layer 2, and adhesive layer 32 is also formed on the other side of the adhesive layer 2. Although adhesive layer 32 is formed over the entire surface of the other side of the adhesive layer 2, it may also be formed on a part of the other side of the adhesive layer 2. Furthermore, in Figure 2, adhesive layer 31 may also be formed on a part of one side of the adhesive layer 2.

[0025] The laminate of the present invention may include a release liner. Specifically, if an adhesive layer is located on one surface of the laminate of the present invention and an adhesive layer is located on the other surface, the laminate of the present invention may have a release liner bonded to the one surface, or to the other surface, or to both surfaces. Also, if adhesive layers are located on both surfaces of the laminate of the present invention, a release liner may be bonded to one surface, or to both surfaces. Furthermore, if both sides of the laminate of the present invention are protected by a release liner, each side may be protected by two release liners, or it may be protected by a single release liner with both sides being release surfaces, in a rolled form (winding body). The release liner is used as a protective material for the laminate and is peeled off when it is attached to a substrate. Note that the release liner is not necessarily required.

[0026] In the laminate 1 shown in Figure 3, the release liner 4 is bonded to the adhesive layer 2 so as to be in contact with it. That is, the laminate 1 shown in Figure 3 comprises the adhesive layer 3, the adhesive layer 2, and the release liner 4 in this order. The laminate 1 shown in Figure 3 is the same as Figure 1 except that the release liner 4 is bonded to the adhesive layer 2.

[0027] In the laminate 1 shown in Figure 4, the release liner 4 is bonded to the adhesive layer 3 so as to be in contact with it. That is, the laminate 1 shown in Figure 4 comprises the adhesive layer 2, the adhesive layer 3, and the release liner 4 in this order. The laminate 1 shown in Figure 4 is the same as Figure 1 except that the release liner 4 is bonded to the adhesive layer 3.

[0028] The laminate 1 shown in Figure 5 comprises multiple adhesive layers 3, with adhesive layer 31 and adhesive layer 32. A release liner 4 is bonded to the adhesive layer 31 in contact with it. That is, the laminate 1 shown in Figure 5 comprises adhesive layer 32, adhesive layer 2, adhesive layer 31, and release liner 4 in this order. The laminate 1 shown in Figure 5 is the same as in Figure 2, except that the release liner 4 is bonded to adhesive layer 31. Here, the release liner 4 may also be bonded to adhesive layer 32.

[0029] The laminate of the present invention may comprise a plurality of release liners. For example, the laminate of the present invention may comprise a release liner on one surface of the laminate, on the other surface of the laminate, or on both the one surface and the other surface. The plurality of release liners may be the same layer or different layers in terms of thickness, composition, shape, or physical properties.

[0030] The laminate 1 shown in Figure 6 comprises a plurality of release liners 4, with release liners 41 and 42. Release liner 41 is bonded to one surface of the laminate 1 (the surface on the side where the adhesive layer 3 of the adhesive layer 2 is laminated). Release liner 42 is bonded to the other surface of the laminate 1 (the surface opposite to the side where the adhesive layer 3 of the adhesive layer 2 is laminated). The laminate 1 shown in Figure 6 is the same as in Figure 1, except that it comprises release liners 41 and 42.

[0031] The laminate 1 shown in Figure 7 comprises a plurality of release liners 4, with release liners 41 and 42. The laminate 1 shown in Figure 7 also comprises a plurality of adhesive layers 3, with adhesive layers 31 and 32. The release liner 41 is bonded to one surface of the laminate 1 (the surface on the side where the adhesive layer 31 of the adhesive layer 2 is laminated). The release liner 42 is bonded to the other surface of the laminate 1 (the surface opposite to the side where the adhesive layer 31 of the adhesive layer 2 is laminated). The laminate 1 shown in Figure 7 is the same as in Figure 2, except that it comprises release liners 41 and 42.

[0032] The laminate of the present invention may comprise multiple adhesive layers. For example, the laminate of the present invention may have a thick adhesive layer formed by laminating multiple adhesive layers. The multiple adhesive layers may have the same thickness, composition, shape, or physical properties, or they may be different.

[0033] In the laminate of the present invention, the ratio of the thickness of the adhesive layer to the thickness of the adhesive layer [thickness of adhesive layer:thickness of adhesive layer] is preferably 1:0.0001 to 1:1, more preferably 1:0.0025 to 1:0.75, and even more preferably 1:0.005 to 1:0.5. When the thickness of the adhesive layer is greater than 1:1, the thickness of the adhesive layer is sufficient relative to the thickness of the adhesive layer, resulting in superior resistance to bending. When the thickness of the adhesive layer is less than 1:1, the ability to follow steps is superior. When the thickness of the adhesive layer is greater than 1:0.0001, the thickness of the adhesive layer is sufficient relative to the thickness of the adhesive layer, resulting in superior adhesion to alkali-free glass and chemically strengthened glass. Furthermore, when the thickness of the adhesive layer is less than 1:0.0001, adhesive overflow from the adhesive layer and blocking between laminates can be further suppressed. Furthermore, if the adhesive layer and the bonding layer are each composed of multiple layers (a single layer formed by the contact of multiple layers), the above thickness is the total thickness of the multiple layers. Also, if bonding layers are provided on both sides of the adhesive layer, one side and the other side, the bonding layer in the above ratio refers to the layer provided on the same side as the adhesive layer. That is, the bonding layer in the above ratio is the bonding layer formed on the one side (for example, bonding layer 31 in Figure 2) or the bonding layer formed on the other side (for example, bonding layer 32 in Figure 2). Here, if bonding layers are provided on both sides of the adhesive layer, the ratio of the thickness of the adhesive layer to the thickness of the bonding layer formed on the one side (for example, [thickness of adhesive layer 2:thickness of bonding layer 31] in Figure 2), and the ratio of the thickness of the adhesive layer to the thickness of the bonding layer formed on the other side (for example, [thickness of adhesive layer 2:thickness of bonding layer 32] in Figure 2), may be the same or different.

[0034] In the laminate of the present invention, the ratio of the elastic modulus of the adhesive layer at 25°C to the elastic modulus of the adhesive layer at 25°C [elastic modulus of the adhesive layer at 25°C / elastic modulus of the adhesive layer at 25°C] is 2 or more, preferably 5 or more, more preferably 10 or more, and even more preferably 25 or more. 2 It may be more than 10 3 or more, or 104 It may be greater than or equal to 2. When the above ratio is 2 or greater, it is superior in achieving both adhesion to alkali-free glass and chemically strengthened glass and flexibility. Also, the above ratio may be 10 7 The following is also acceptable, 10 6 The following may also apply. If the adhesive layer is curable, the elastic modulus may be the elastic modulus of the adhesive layer before curing or the elastic modulus of the adhesive layer after curing. Also, if the adhesive layer is curable, the elastic modulus may be the elastic modulus of the adhesive layer before curing or the elastic modulus of the adhesive layer after curing, but it is preferable that it is the elastic modulus of the adhesive layer after curing. That is, if the adhesive layer is curable, it is preferable that the elastic modulus of the adhesive layer at 25°C is smaller than the elastic modulus of the adhesive layer at 25°C after curing. Furthermore, if the adhesive layer is curable, it is preferable that the elastic modulus of the adhesive layer at 25°C in the above ratio is the elastic modulus of the adhesive layer at 25°C after curing.

[0035] In the laminate of the present invention, the peel force between the adhesive layer and the tack layer in a T-type peel test under the conditions of 23°C and a peeling speed of 300 mm / min may be greater than 0.25 N / 25 mm, greater than 0.5 N / 25 mm, or greater than 1.0 N / 25 mm. Furthermore, in the laminate of the present invention, the adhesive layer (or tack layer) may be so tightly adhered to the tack layer (or adhesive layer) that it cannot be peeled off. If the tack layer is curable, the tack layer in the peel force may be the tack layer before curing or the tack layer after curing. Also, if the adhesive layer is curable, the adhesive layer in the peel force may be the tack layer before curing or the tack layer after curing, but it is preferable that it be the tack layer after curing.

[0036] (Adhesive layer) The adhesive layer can be a known or conventional adhesive layer. Preferably, the adhesive layer is a solvent-free adhesive layer containing a photopolymerized polymer as the base polymer. Such an adhesive layer can be manufactured from a solvent-free adhesive composition. When manufacturing the adhesive layer from a solvent-free adhesive composition, there is no need to remove the solvent by volatilizing it from the coating film of the composition. Therefore, a laminate comprising the adhesive layer is suitable for reducing environmental impact.

[0037] The adhesive layer is preferably a sheet-like pressure-sensitive adhesive (solvent-free adhesive sheet) formed from a solvent-free adhesive composition. Therefore, the adhesive layer (solvent-free adhesive composition) preferably contains at least a photopolymerizable polymer as a base polymer. A photopolymerizable polymer is a polymer formed by a polymerization method in which the polymerization reaction of polymerizable components is advanced by irradiation with active energy rays such as ultraviolet light. Depending on the type of polymerization reaction, a thermal polymerization initiator or a photopolymerization initiator (photoradical generator, photoinitiator) can be used as the polymerization initiator used in the polymerization reaction. Only one type of polymerization initiator may be used, or two or more types may be used.

[0038] The base polymer is an adhesive component that exhibits tackiness in the adhesive layer described above. The base polymer is not particularly limited, but examples include acrylic polymers, rubber polymers (such as natural rubber polymers and synthetic rubber polymers), silicone polymers, polyester polymers, urethane polymers, polyamide polymers, epoxy polymers, vinyl alkyl ether polymers, and fluorine polymers. One type of base polymer may be used, or two or more types may be used.

[0039] The content of the base polymer in the adhesive layer is not particularly limited, but is preferably 75% by mass or more (for example, 75 to 99.9% by mass) and more preferably 85% by mass or more (for example, 85 to 99.9% by mass) based on the total amount (100% by mass) of the adhesive layer.

[0040] The above adhesive layer may contain other components in addition to the above-described components as long as the effects of the present invention are not impaired. Examples of the other components include crosslinking agents, curing agents, curing catalysts, crosslinking accelerators, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), anti-aging agents, fillers (metal powders, organic fillers, inorganic fillers, etc.), colorants (pigments, dyes, etc.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, rust preventives, particulate materials, foil materials, flame retardants, silane coupling agents, ion trap agents, and the like. Each of the above other components may be used alone or in combination of two or more.

[0041] The thickness of the above adhesive layer is preferably 5 to 2500 μm, more preferably 10 to 1000 μm, and even more preferably 15 to 500 μm. When the thickness of the adhesive layer is 5 μm or more, the adhesion to the base material and the decorative layer is excellent. When the thickness of the adhesive layer is 2500 μm or less, when the base material is bent, it is difficult for creases to occur due to the deformation of the adhesive layer. When the adhesive layer is composed of multiple layers (a single layer formed by contact of multiple layers), the above thickness is the total thickness of the multiple layers.

[0042] The elastic modulus of the above adhesive layer at 25°C is 3 ~ 6 Pa, preferably 2×10 3 ~ 5 Pa, more preferably 5×10 3 ~ 5 Pa. When the elastic modulus of the above adhesive layer at 25°C is 10[[ID=2,2]] 3 Pa or more, it has appropriate cohesive force and excellent adhesion to the adhesive layer. When the elastic modulus of the above adhesive layer at 25°C is 10 6 Pa or less, it has excellent flexibility and flex resistance. When the adhesive layer has curability, the elastic modulus may be the elastic modulus of the adhesive layer before curing or the elastic modulus of the adhesive layer after curing.

[0043] The elastic modulus of the above adhesive layer at -20°C is 10 3 ~10 9 Pa is preferred, futur2×10 3 ~5×10 7 Pa, more preferably 5 × 10 3 ~10 6 The elastic modulus of the above adhesive layer at -20°C is 10 3 If the elastic modulus of the above adhesive layer is Pa or higher, it has appropriate cohesive force and superior adhesion to the adhesive layer. 9 If the elastic modulus is Pa or less, it provides superior flexibility and bending resistance. If the adhesive layer is curable, the elastic modulus may be the elastic modulus of the adhesive layer before curing, or the elastic modulus of the adhesive layer after curing.

[0044] The elastic modulus of the above adhesive layer at 60°C is 5 × 10 2 ~10 6 Pa is preferred, and more preferably 10 3 ~5×10 5 Pa, more preferably 2 × 10 3 ~10 5 The elastic modulus of the above adhesive layer at 60°C is 5 × 10⁻⁶. 2 If the elastic modulus of the adhesive layer is Pa or higher, it has appropriate cohesive force and superior adhesion to the adhesive layer. 6 If the elastic modulus is Pa or less, it provides superior flexibility and bending resistance. If the adhesive layer is curable, the elastic modulus may be the elastic modulus of the adhesive layer before curing, or the elastic modulus of the adhesive layer after curing.

[0045] The above modulus of elasticity is the storage modulus, which is a value measured by dynamic viscoelasticity. The above storage modulus may be the shear modulus or the tensile modulus, but it is preferably the shear modulus. The above storage modulus can be controlled by the type of base polymer constituting the adhesive layer, the monomer composition, the weight-average molecular weight, the amount of crosslinking agent used (amount added), and the type and content of other additives.

[0046] The glass transition temperature of the adhesive layer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower. When the glass transition temperature is 0°C or lower, it exhibits tack more easily, making it easier to bond with the adhesive layer and the adherend. Furthermore, the glass transition temperature is preferably -80°C or higher, more preferably -70°C or higher, and even more preferably -60°C or higher. When the glass transition temperature is -80°C or higher, it is easier to further improve the adhesive strength. If the adhesive layer is curable, the glass transition temperature may be the glass transition temperature of the adhesive layer before curing, or the glass transition temperature of the adhesive layer after curing.

[0047] The glass transition temperature may be determined using the peak temperature value of tanδ obtained by dynamic mechanical analysis (DMA), or it may be determined using the median temperature value of the baseline shift obtained by differential scanning calorimetry (DSC). The glass transition temperature can be controlled by the type of base polymer constituting the adhesive layer, the monomer composition, the weight-average molecular weight, the amount of crosslinking agent used (amount added), and the type and content of other additives.

[0048] The adhesive layer described above may or may not have curability, but it is preferable that it does not. Examples of curability include active energy ray curability, thermosetting, and moisture curability. Examples of active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays.

[0049] (adhesive layer) The adhesive layer described above can be a known or conventional adhesive layer. In one embodiment, the adhesive layer may contain a heat-transferable resin. When the adhesive layer contains a heat-transferable resin, the adhesive layer, which is made on a temporary substrate separate from the alkali-free glass or chemically strengthened glass, can be formed by heating and transferring it onto the alkali-free glass or chemically strengthened glass, resulting in superior adhesion to the alkali-free glass and chemically strengthened glass. In this specification, "heat-transferable resin" is a resin in which a single layer of resin formed using the heat-transferable resin can be transferred to a substrate at a heating temperature (for example, at least one temperature between 40 and 150°C). The adhesive layer may contain only one type of heat-transferable resin, or it may contain two or more types.

[0050] The above-mentioned heat-transferable resin preferably satisfies at least one of the following conditions: (1) the ratio of the elastic modulus at the heating temperature (for example, at least one temperature between 40 and 150°C) to the elastic modulus at 25°C [elastic modulus at heating temperature / elastic modulus at 25°C] is 1 / 2 or less, or (2) the softening point is between 0 and 150°C.

[0051] The ratio of the elastic moduli is more preferably 1 / 5 or less, and even more preferably 1 / 10 or less. When the ratio of the elastic moduli is 1 / 2 or less, the adhesive layer is not sticky at room temperature and is easy to handle, and when heated, it becomes sticky and can be transferred to the substrate.

[0052] The above softening point is more preferably 20 to 150°C, and even more preferably 40 to 150°C. If the above softening point is 0°C or higher, the adhesive layer is less sticky at room temperature and easier to handle, resulting in superior handling properties. If the above softening point is 150°C or lower, stickiness can be generated by heating with less energy, allowing for energy-saving transfer to the substrate. If the above adhesive layer is curable, the above softening point of the adhesive layer may be the softening point of the adhesive layer before curing, or the softening point of the adhesive layer after curing. Furthermore, it is preferable that the above softening point of the adhesive layer is the softening point before heat transfer.

[0053] The above softening point can be measured by any of the methods specified in JIS K7234 (Environmental Method), JIS K7234 (Mercury Replacement Method), or JIS K7206 (Vicat Softening Temperature). The above softening point can be controlled by the type of base polymer constituting the above heat transferable resin, the monomer composition, the weight-average molecular weight, the amount of crosslinking agent used (amount added), and the type and content of other additives.

[0054] Examples of the above-mentioned heat-transferable resins include various polymers that exhibit rubber elasticity at room temperature, such as acrylic polymers, epoxy polymers, rubber polymers (natural rubber, synthetic rubber, mixtures thereof, etc.), polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluoropolymers. The above-mentioned heat-transferable resin may be used alone or in combination of two or more types. In particular, the above-mentioned heat-transferable resin preferably contains one or more selected from the group consisting of acrylic polymers, epoxy polymers, and urethane polymers, more preferably contains two or more selected from the group consisting of acrylic polymers, epoxy polymers, and urethane polymers, and even more preferably contains an acrylic polymer, and further contains an epoxy polymer and / or a urethane polymer. In this specification, the above-mentioned polymer refers to a polymer having monomer-derived structural units, and the weight-average molecular weight and number-average molecular weight are not particularly limited. For example, compounds with a weight-average molecular weight or number-average molecular weight of about 1000 are also included in the above-mentioned polymer.

[0055] The glass transition temperature (Tg) of the above-mentioned heat-transferable resin is preferably less than 200°C, more preferably 180°C or lower, even more preferably 150°C or lower, and particularly preferably 125°C or lower. When the glass transition temperature is less than 200°C, it exhibits tack easily, making it easier to bond with the adhesive layer and the adherend. Furthermore, it does not become too brittle and has appropriate flexibility, making it easier to absorb loads such as bending, resulting in superior processability and quality reliability. The glass transition temperature is preferably, for example, -80°C or higher, more preferably -40°C or higher, even more preferably -20°C or higher, and particularly preferably 0°C or higher. It may also be 10°C or higher, 20°C or higher, 40°C or higher, or 60°C or higher. When the glass transition temperature is -80°C or higher, it is easier to improve the adhesive strength. Generally, adhesive strength tends to decrease at high temperatures, but when the glass transition temperature is 0°C or higher, the adhesive strength during heating can be further improved. Furthermore, it is preferable that the glass transition temperature of the adhesive layer is within the above range. If the adhesive layer is curable, the glass transition temperature of the adhesive layer may be the glass transition temperature of the adhesive layer before curing, or the glass transition temperature of the adhesive layer after curing.

[0056] The difference between the glass transition temperature of the adhesive layer and the glass transition temperature of the adhesive layer [(glass transition temperature of the adhesive layer) - (glass transition temperature of the adhesive layer)] is preferably 220°C or less, more preferably 200°C or less, and even more preferably 180°C or less. When the difference is 220°C or less, tack is easily exhibited, and bonding with the adhesive layer and the adherend is made easier. Furthermore, the difference is preferably 50°C or more, more preferably 60°C or more, and even more preferably 70°C or more. When the difference is 50°C or more, the adhesive strength during heating is made easier to improve. If the adhesive layer is curable, the glass transition temperature may be the glass transition temperature of the adhesive layer before curing, or the glass transition temperature of the adhesive layer after curing. Furthermore, if the adhesive layer is curable, the glass transition temperature may be the glass transition temperature of the adhesive layer before curing, or the glass transition temperature of the adhesive layer after curing.

[0057] For the glass transition temperature (Tg) of a heat transfer resin, the theoretical glass transition temperature (Tg) can be obtained based on Fox's equation, as shown below. Fox's equation is a relationship between the glass transition temperature Tg of a polymer and the glass transition temperature Tgi of the homopolymer of the monomers constituting the polymer. In Fox's equation below, Tg represents the glass transition temperature (°C) of the polymer, Wi represents the weight fraction of monomer i constituting the polymer, and Tgi represents the glass transition temperature (°C) of the homopolymer formed from monomer i. For the glass transition temperature of the homopolymer, literature values ​​can be used. For example, "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999) lists the glass transition temperatures of various homopolymers. On the other hand, the glass transition temperature of the monomer homopolymer can also be determined by the method specifically described in Japanese Patent Publication No. 2007-51271. Fox's formula 1 / (273+Tg)=Σ[Wi / (273+Tgi)]

[0058] Furthermore, the glass transition temperature may be determined using the peak temperature value of tanδ obtained by dynamic viscoelasticity measurement, or it may be determined using the median temperature value of the baseline shift obtained by differential scanning calorimetry. The glass transition temperature can be controlled by the type of base polymer constituting the adhesive layer, the monomer composition, the weight-average molecular weight, the amount of crosslinking agent used (amount added), and the type and content of other additives.

[0059] Furthermore, when the peak temperature value of tanδ, determined by dynamic viscoelasticity measurement, is adopted as the glass transition temperature, the storage modulus used to determine tanδ may be either the shear modulus or the tensile modulus. However, if the adhesive layer is curable, the modulus of elasticity after curing will be high, and it may not be possible to perform the measurement properly, such as when slippage occurs between the adhesive layer and the measuring jig when measuring the shear modulus. For this reason, if it is not possible to properly measure the shear modulus (for example, if the modulus of elasticity is 10 8If it exceeds [a certain value], it is preferable to determine tanδ based on the tensile modulus.

[0060] The adhesive layer preferably contains the heat-transferable resin as a base polymer. The content of the base polymer in the adhesive layer is not particularly limited, but is preferably 75% by mass or more (for example, 75 to 99.9% by mass) and more preferably 85% by mass or more (for example, 85 to 99.9% by mass) based on the total amount (100% by mass) of the adhesive layer.

[0061] The content of the heat-transferable resin in the base polymer is not particularly limited, but is preferably 75% by mass or more (for example, 75 to 99.9% by mass) and more preferably 85% by mass or more (for example, 85 to 99.9% by mass) based on the total amount (100% by mass) of the base polymer.

[0062] The adhesive layer described above preferably has curability. Examples of curability include active energy ray curability, thermosetting, and moisture curability. Examples of active energy rays include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays.

[0063] The adhesive layer may contain a curable resin. Examples of curable resins include active energy ray curable resins, thermosetting resins, and moisture-curable resins. The adhesive layer may contain only one type of curable resin, or two or more types. Furthermore, the heat transfer resin may also be curable. That is, the heat transfer resin may be a curable resin. A heat transfer resin with curability may be included in the content of either the heat transfer resin or the thermosetting resin.

[0064] As the thermosetting resin mentioned above, known or conventional thermosetting resins can be used, for example, resins having thermosetting functional groups. Examples of the thermosetting functional groups include epoxy group-containing groups such as glycidyl groups, carboxyl groups, hydroxyl groups, isocyanate groups, and aziridyl groups. The thermosetting functional group may be one type or two or more types.

[0065] Examples of the thermosetting resins mentioned above include epoxy resins, phenolic resins, urea resins, melamine resins, unsaturated polyester resins, bismaleimide resins, polyurethane resins, diallyl phthalate resins, silicone resins, polyimide resins, polyamideimide resins, and benzocyclobutene resins.

[0066] As the active energy ray curable resin mentioned above, known or conventional active energy ray curable resins can be used, for example, resins having active energy ray curable functional groups. Examples of the active energy ray curable functional groups include epoxy group-containing groups such as glycidyl groups, and ethylenically unsaturated groups such as allyl groups, acryloyl groups, and methacryloyl groups. The active energy ray curable functional group may be one type or two or more types.

[0067] Examples of the above-mentioned active energy ray curable resins include resins having two or more of the above-mentioned active energy ray curable functional groups in one molecule, such as epoxy resins, polyester acrylic resins, polyether acrylic resins, urethane acrylic resins, carbonate acrylic resins, epoxy acrylic resins, and other acrylic resins.

[0068] The adhesive layer described above may contain other components besides those listed above, as long as they do not impair the effects of the present invention. Examples of these other components include crosslinking agents, curing agents, curing catalysts, crosslinking accelerators, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), anti-aging agents, fillers (metal powders, organic fillers, inorganic fillers, etc.), colorants (pigments, dyes, etc.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, UV absorbers, polymerization inhibitors, rust inhibitors, granular materials, foil-like materials, flame retardants, silane coupling agents, ion trapping agents, photoacid generators, thermal polymerization initiators, and photopolymerization initiators (photoradical generators, photoinitiators). Each of these other components may be used individually or in combination of two or more.

[0069] The thickness of the adhesive layer is preferably 0.01 to 50 μm, more preferably 0.05 to 35 μm, and even more preferably 0.1 to 20 μm. When the thickness of the adhesive layer is 0.01 μm or more, adhesion to alkali-free glass and chemically strengthened glass is superior. When the thickness of the adhesive layer is 50 μm or less, the step of the adhesive layer is small and the appearance is good. When the adhesive layer is composed of multiple layers (a single layer formed by the contact of multiple layers), the above thickness is the total thickness of the multiple layers. Furthermore, if the laminate of the present invention includes a decorative layer (details described later), and there is a portion comprising adhesive layer A, decorative layer, adhesive layer B, and adhesive layer in this order, the thickness of the adhesive layer is the thickness of adhesive layer A, that is, the thickness of the adhesive layer located on the side opposite to the side where the adhesive layer of the decorative layer is located.

[0070] The elastic modulus of the above adhesive layer at 25°C is 10 4 ~10 10 Pa is preferred, and more preferably 3 × 10 4 ~1 × 10 9 Pa, more preferably 5 × 10 4 ~5×10 8 The elastic modulus of the above adhesive layer at 25°C is 10 4When the elastic modulus of the adhesive layer is Pa or higher, it has appropriate cohesive force and superior adhesion to the adhesive layer and substrate. 10 If the elastic modulus is Pa or less, it is possible to maintain appropriate flexibility and bending resistance. If the adhesive layer has curability, the elastic modulus may be the elastic modulus of the adhesive layer before curing or the elastic modulus of the adhesive layer after curing, but it is preferable to use the elastic modulus of the adhesive layer before curing.

[0071] If the above adhesive layer has a glass transition temperature (Tg), the elastic modulus at (Tg + 20)°C is 10 3 ~10 7 Pa is preferred, and more preferably 3 × 10 3 ~5×10 6 Pa, more preferably 5 × 10 3 ~1 × 10 6 The elastic modulus of the above adhesive layer at (Tg+20)°C is 10 3 When the elastic modulus of the adhesive layer is Pa or higher, it has a moderate cohesive force and superior adhesion to the adhesive layer and substrate. 7 If the elastic modulus is Pa or less, it is possible to maintain appropriate flexibility and bending resistance. If the adhesive layer has curability, the elastic modulus may be the elastic modulus of the adhesive layer before curing or the elastic modulus of the adhesive layer after curing, but it is preferable to use the elastic modulus of the adhesive layer before curing.

[0072] Furthermore, if the adhesive layer is curable, the elastic modulus of the cured adhesive layer at 25°C is 10 6 ~10 10 Pa is preferred, and more preferably 5 × 10 6 ~5×10 9 Pa, more preferably 1 × 10 7 ~1 × 10 9 The elastic modulus of the above-mentioned cured adhesive layer at 25°C is 10 6 If the elastic modulus of the cured adhesive layer is Pa or higher, the adhesion to the adhesive layer and substrate is superior. 10If the elastic modulus is below Pa, it is possible to maintain appropriate flexibility and bending resistance. Furthermore, it is preferable that the elastic modulus of the cured adhesive layer at 60°C is within the above range, the elastic modulus of the cured adhesive layer at 80°C is within the above range, and the elastic modulus of the cured adhesive layer at 100°C is within the above range. If the adhesive layer is curable, if the elastic modulus after curing is within the above range, it is possible to maintain a high elastic modulus even at high temperatures, resulting in superior adhesive reliability.

[0073] The above modulus of elasticity is the storage modulus, which is a value measured by dynamic viscoelasticity. The above storage modulus may also be the shear modulus or the tensile modulus. However, if the adhesive layer is curable, the modulus of elasticity after curing will be high, and when measuring the shear modulus, slippage may occur between the adhesive layer and the measuring jig, making it impossible to perform the measurement properly. For this reason, if the shear modulus cannot be measured properly (for example, if the modulus of elasticity is 10 8 If it exceeds a certain value, the storage modulus is preferably the tensile modulus. The storage modulus can be controlled by the type of base polymer constituting the heat transferable resin, the monomer composition, the weight-average molecular weight, the amount of crosslinking agent used (amount added), and the type and content of other additives.

[0074] (compatible layer) The laminate of the present invention may have a compatible layer at the interface between the adhesive layer and the adhesive layer. The compatible layer is a layer formed by compatibility near the boundary between the adhesive layer and the adhesive layer. The mechanism by which the compatible layer is formed is not particularly limited, but for example, when the adhesive layer and the adhesive layer are bonded together by lamination or the like, at least a portion of the adhesive layer may mix with at least a portion of the adhesive layer. Alternatively, when the adhesive composition is directly applied (coated) onto the adhesive layer, at least a portion of the adhesive composition may mix with at least a portion of the adhesive layer. Furthermore, the formation of the compatible layer can be promoted by heating or the like at the time of bonding, the time of direct application, or at any point after the adhesive layer and the adhesive layer have been laminated. The formation of the compatible layer improves the adhesion between the adhesive layer and the adhesive layer, thereby suppressing peeling that may occur between the adhesive layer and the adhesive layer when bending and folding operations are repeated, and as a result, the occurrence of peeling and creases is further suppressed.

[0075] The thickness of the compatible layer is preferably 10 nm to 20 μm, more preferably 20 nm to 10 μm, and even more preferably 30 nm to 5 μm. When the thickness of the compatible layer is 10 nm or more, the adhesion between the adhesive layer and the tack layer is improved. When the thickness of the compatible layer is 20 μm or less, the influence on the elastic modulus of the tack layer can be further suppressed, resulting in improved flexibility and bending resistance.

[0076] The thickness ratio R of the compatible layer, defined by the following formula (1), is not particularly limited, but is preferably 0.01 to 0.99, more preferably 0.02 to 0.95, and even more preferably 0.05 to 0.9. When R is 0.01 or higher, the adhesion between the adhesive layer and the tack layer is superior. When R is 0.99 or lower, the influence on the elastic modulus of the tack layer can be further suppressed, resulting in superior flexibility and bending resistance. The compatible layer can be confirmed, for example, by observing the cross-section of an optical element using spectroscopic analysis such as infrared absorption spectroscopy (IR method) or by observation with a transmission electron microscope (TEM), and its thickness can be measured.

[0077] R = [DC / (DC + DB)] (1)

[0078] In the above formula (1), DB is the thickness of the adhesive layer and DC is the thickness of the compatible layer.

[0079] (Removable liner) The laminate of the present invention may have a release liner bonded to at least one surface (the surface of the adhesive layer or tack layer) until use. When both sides of the laminate of the present invention are protected with a release liner, it may be protected by two release liners, or it may be protected by a single release liner with both sides being release surfaces, wound in a roll shape (winding body). The release liner is used as a protective material for the laminate and is peeled off when it is attached to the substrate. Note that the release liner is not necessarily required.

[0080] The above-mentioned release liner can be conventional release paper or the like, and is not particularly limited, but examples include a substrate having a release treatment layer, a low-adhesion substrate made of a fluoropolymer, or a low-adhesion substrate made of a nonpolar polymer. Examples of the substrate having the release treatment layer include plastic films and paper surface-treated with release agents such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide. Examples of fluorine-based polymers in the low-adhesion substrate made of a fluoropolymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer. Examples of the above-mentioned nonpolar polymer include olefin resins (e.g., polyethylene, polypropylene, etc.). The release liner can be formed by known or conventional methods. The thickness of the release liner is also not particularly limited.

[0081] (base material) The laminate of the present invention may have a substrate on one of its surfaces (the surface of the adhesive layer or the tack layer). When the laminate of the present invention has a substrate, it is preferable that the adhesive layer is in contact with the substrate from the viewpoint of excellent adhesion to the substrate. The substrate can be a known or conventional substrate. The substrate is preferably an optically transparent substrate. The substrate is not particularly limited, but is preferably glass. The glass is not particularly limited, but may be alkali-free glass or chemically strengthened glass. Furthermore, the substrate can be thin. For example, ultra-thin glass can be used.

[0082] Alkali-free glass refers to glass that contains less alkali components (e.g., alkali metal oxides such as Na2O and K2O) than conventional alkali glass. However, alkali-free glass also includes glass that contains only trace amounts of alkali components. In this specification, the alkali component (alkali metal oxide) content in alkali-free glass may be, for example, 1% by mass or less, 0.1% by mass or less, or 0.05% by mass or less, or it may be substantially free of alkali components. Here, "substantially free" means that it is not contained except for unavoidable impurities.

[0083] Chemically strengthened glass offers superior bending resistance and impact resistance compared to unstrengthened glass. Furthermore, chemically strengthened glass possesses excellent mechanical strength, allowing for the use of thinner glass.

[0084] Chemically strengthened glass is glass whose mechanical properties have been enhanced by chemical means through ion exchange near the glass surface, and it has a compressive stress layer on its surface. Chemically strengthened glass has a high potassium content on its surface, resulting in compressive stress on the surface. For example, by performing ion exchange at a temperature below the glass transition temperature, alkali metal ions with small ionic radii (e.g., lithium ions, sodium ions) on the glass surface are replaced with other alkali ions with larger ionic radii (e.g., sodium ions, potassium ions). This leaves compressive stress on the glass surface, improving the strength of the glass.

[0085] Chemically strengthened glass typically has a rectangular parallelepiped shape, or a hexahedron. Chemically strengthened glass has two faces (first and second principal faces) and four sides. Typically, chemically strengthened glass is hexahedral glass, where all faces are chemically strengthened. Hexahedral glass can be obtained, for example, by chemically strengthening a glass plate. Alternatively, chemically strengthened glass may be 2-sided glass, obtained by cutting hexahedral glass to a desired size.

[0086] Examples of glass materials that make up chemically strengthened glass include aluminosilicate glass, soda-lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborsilicate glass.

[0087] Chemically strengthened glass has a higher potassium ion concentration on its surface than near the center in the thickness direction. Therefore, glass can be identified as chemically strengthened glass by the following method. For example, if the glass is divided into 10 sections in the thickness direction, and the potassium ion concentrations in each section are labeled d1, d2, d3, ..., d10 from the outermost surface, then the glass can be identified as chemically strengthened glass if the potassium ion concentrations satisfy both d1 > d5 and d10 > d5. The potassium concentration distribution in the thickness direction can be measured, for example, by energy-dispersive X-ray analysis (EDX). Specifically, EDX mapping can be performed on the side surface of the glass substrate in the thickness direction using Oxford Instruments' "X-MaxN" at an acceleration voltage of 10 kV to quantify the potassium concentration.

[0088] As chemically strengthened glass, ultra-thin glass can be used. Commercially available chemically strengthened glass can be used as appropriate, for example, Corning's "Gorilla Glass," and as ultra-thin glass, examples include SCHOTT's "SCHOTT UTG," Corning's "Willow Glass," and Nippon Electric Glass's "Dinorex UTG."

[0089] The thickness of the substrate (thickness of alkali-free glass or chemically strengthened glass) is preferably 10 to 2000 μm, more preferably 15 to 1000 μm, and even more preferably 20 to 500 μm, from the viewpoint of excellent flexibility and impact resistance.

[0090] (Decorative layer) The laminate of the present invention may include a decorative layer. The decorative layer is a layer in OLED display devices and the like that is intended to prevent external light from penetrating the OLED element, and is a layer that has reflectivity and light-shielding properties. Since such decorative layers generally do not adhere well to thin glass, they are often formed by bonding them to a plastic substrate, and then incorporated into OLED display devices and the like by laminating the plastic substrate onto thin glass. In recent years, there has been a demand for thinner optical products such as OLED display devices. Therefore, attempts have been made to form the decorative layer directly onto thin glass without using a plastic substrate. Such laminates contribute to thinner designs because they do not require the use of a plastic substrate for forming the decorative layer. In particular, foldable devices require even thinner designs so that they can be easily folded. As thin glass in such foldable devices, alkali-free glass or chemically strengthened glass with high flexibility resistance may be used. However, conventional decorative layers have low adhesion to alkali-free glass and chemically strengthened glass, making it difficult to form the decorative layer on alkali-free glass or chemically strengthened glass using conventional methods such as screen printing. Furthermore, even if it were possible to form the decorative layer, there were problems such as the decorative layer easily detaching from the alkali-free or chemically strengthened glass when subjected to impact or repeated bending.

[0091] In this case, when the laminate of the present invention includes a decorative layer, the decorative layer exhibits high adhesion to alkali-free glass and chemically strengthened glass, and the laminate can be provided in which the decorative layer is less likely to fall off. One embodiment of the laminate of the present invention, in which the laminate includes a base material and a decorative layer, will be described with reference to Figures 8 to 12.

[0092] When the laminate of the present invention comprises a substrate and a decorative layer, the adhesive layer is preferably formed to be in contact with at least one of the adhesive layer and the decorative layer, and is preferably formed to be in contact with at least the adhesive layer from the viewpoint of superior adhesion of the adhesive layer to the substrate. In particular, it is more preferable that the adhesive layer is formed to cover both the adhesive layer and the decorative layer from the viewpoint of more reliably preventing the decorative layer from falling off. Furthermore, the adhesive layer is preferably provided on at least a part of the substrate, and may be provided on the entire surface of the substrate.

[0093] In the laminate of the present invention, the decorative layer may be a single layer or multiple layers. By forming multiple layers, a thicker decorative layer can be formed, and if the decorative layer has light-shielding properties, the light-shielding properties can be made even higher. When the decorative layer is multiple layers, the thickness and formation areas of the multiple decorative layers may be the same or different.

[0094] In the laminate of the present invention, the adhesive layer may be laminated on at least a part of the substrate or on the entire surface.

[0095] Figures 8 to 12 show cross-sectional views of one embodiment of the laminate of the present invention. The laminate 1 shown in Figure 8 comprises a base material 5, an adhesive layer 3, a decorative layer 6, and a tack layer 2. The adhesive layer 3 is formed to be in contact with a part of the base material 5. The shape of the adhesive layer 3 is not particularly limited, but for example, in the view of preventing light from entering the interior when the decorative layer 6 has light-shielding properties, it is formed in a frame shape (annular, picture frame shape, etc.) along the edge of the base material 5. The adhesive layer 3 only needs to be formed on at least a part of the side of the base material 5 where the decorative layer 6 is located, and may be formed on the entire surface of the side of the base material 5 where the decorative layer 6 is located. The decorative layer 6 is laminated via the adhesive layer 3. In other words, the decorative layer 6 is laminated on the adhesive layer 3. The formation region of the decorative layer 6 is preferably a region that coincides with the formation region of the adhesive layer 3, or inside the formation region of the adhesive layer 3. From the viewpoint of improving the adhesion of the decorative layer 6 to the substrate 5 and more reliably preventing the decorative layer 6 from falling off, it is preferable that the area where the decorative layer 6 is formed is inside the area where the adhesive layer 3 is formed. The shape of the decorative layer 6 is not particularly limited, but for example, from the viewpoint of preventing light from entering the interior when the decorative layer 6 has light-shielding properties, it is formed in a frame shape (ring-shaped, picture frame shape, etc.) along the edge of the substrate 5. The adhesive layer 2 is formed so as to cover the entire surface of one side of the substrate 5 (the side with the adhesive layer 3 and the decorative layer 6) with the adhesive layer 3 and the decorative layer 6. The adhesive layer 2 is in contact with both the adhesive layer 3 and the decorative layer 6.

[0096] The laminate 1 shown in Figure 9 is the same as the laminate 1 shown in Figure 8, except that the adhesive layer 3 is formed over the entire surface of one of the surfaces of the base material 5. As shown in Figure 9, the adhesive layer 3 is provided over the entire surface of the base material 5, which further increases the adhesion of the adhesive layer 2 to the base material 5.

[0097] The laminate 1 shown in Figure 10 is the same as the laminate 1 shown in Figure 9, except that the adhesive layer 3 is formed over the entire surface of one side of the substrate 5 and covers the decorative layer 6. When the adhesive layer 3 covers the decorative layer 6 as shown in Figure 10, there is no area where the adhesive layer 2 and the decorative layer 6 come into contact, and the adhesion of the adhesive layer 2 to the substrate 5 becomes even higher.

[0098] The laminate 1 shown in Figure 11 comprises a plurality of adhesive layers 2 and a plurality of adhesive layers 3. The adhesive layers 2 include adhesive layer 21 and adhesive layer 22, and the adhesive layers 3 include adhesive layer 31 and adhesive layer 32. The adhesive layer 22 is provided via an adhesive layer 32 formed on the entire surface of the other side of the base material 5. Other aspects are the same as the laminate shown in Figure 9. In the laminate 1 shown in Figure 11, the adhesive layer 32 is formed on the entire surface of the other side of the base material 5, but it may also be formed on a part of the other side of the base material 5. Also, in Figure 11, the adhesive layer 31 may be formed on a part of one side of the base material 5.

[0099] In the laminate 1 shown in Figure 12, the adhesive layer 31 is formed over the entire surface of one side of the substrate 5 and is also formed to cover the decorative layer 6. Other aspects are the same as those of the laminate 1 shown in Figure 11.

[0100] Furthermore, the laminate of the present invention may not have a base material but may have a decorative layer. As an embodiment in which the laminate of the present invention does not have a base material but has a decorative layer, Figures 13 to 15 show a cross-sectional view of one embodiment of the laminate of the present invention.

[0101] The laminate 1 shown in Figure 13 is the same as the laminate 1 shown in Figure 8, except that it does not have a base material 5. Similarly, the laminate 1 shown in Figure 14 is the same as the laminate 1 shown in Figure 9, except that it does not have a base material 5. Furthermore, the laminate 1 shown in Figure 15 is the same as the laminate 1 shown in Figure 10, except that it does not have a base material 5.

[0102] The decorative layer preferably contains at least a heat-transferable resin. When the decorative layer contains a heat-transferable resin, it can be formed by transferring a decorative layer, which has been prepared on a temporary substrate separate from the base material, to the adhesive layer by heating. Furthermore, when both the adhesive layer and the decorative layer contain a heat-transferable resin, when the adhesive layer is heat-transferred onto the decorative layer, or when the laminate of the adhesive layer and the decorative layer is transferred onto the base material, the area near the boundary between the decorative layer and the adhesive layer becomes compatible, resulting in excellent adhesion between the adhesive layer and the decorative layer, and consequently, excellent adhesion of the decorative layer to the base material (particularly alkali-free glass and chemically strengthened glass). The decorative layer may contain only one type of heat-transferable resin, or it may contain two or more types.

[0103] Examples of the heat-transferable resin in the decorative layer include those exemplified and described as the heat-transferable resin contained in the adhesive layer described above. The preferred embodiment of the heat-transferable resin in the decorative layer is the same as the preferred embodiment of the heat-transferable resin in the adhesive layer.

[0104] The heat-transferable resin in the decorative layer may be the same type as the heat-transferable resin contained in the adhesive layer (for example, acrylic polymer and acrylic polymer), or it may be a different type (for example, acrylic polymer and rubber polymer). When they are the same type, when the decorative layer is heat-transferred onto the adhesive layer, the area near the boundary between the decorative layer and the adhesive layer becomes compatible, resulting in excellent adhesion between the adhesive layer and the decorative layer, and consequently, excellent adhesion of the decorative layer to the substrate (especially alkali-free glass and chemically strengthened glass).

[0105] The decorative layer preferably contains the heat-transferable resin as a base polymer. The content of the base polymer in the decorative layer is not particularly limited, but is preferably 10% by mass or more (for example, 10 to 99.9% by mass) and more preferably 25% by mass or more (for example, 25 to 99.9% by mass) based on the total amount (100% by mass) of the decorative layer.

[0106] The decorative layer may contain a coloring agent. The coloring agent may be a dye or a pigment, as long as it is soluble or dispersible in the decorative layer. Pigments are preferred from the viewpoint of superior weather resistance and durability. One coloring agent may be used alone, or two or more may be used.

[0107] Examples of the above-mentioned colorants include black colorants, cyan colorants, magenta colorants, and yellow colorants. The above-mentioned colorants may be present in a single form or in a form containing two or more types.

[0108] Examples of black colorants include carbon black, carbon nanotubes, graphite, copper oxide, manganese dioxide, azo pigments such as azomethine azoblack, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite, magnetite, chromium oxide, iron oxide, molybdenum disulfide, complex oxide black pigments, anthraquinone-based organic black dyes, and azo-based organic black dyes. Examples of carbon black include furnace black, channel black, acetylene black, thermal black, and lamp black. Examples of black colorants include CI Solvent Black 3, 7, 22, 27, 29, 34, 43, and 70; CI Direct Black 17, 19, 22, 32, 38, 51, and 71; CI Acid Black 1, 2, 24, 26, 31, 48, 52, 107, 109, 110, 119, and 154; CI Disperse Black 1, 3, 10, and 24; and CI Pigment Black 1 and 7.

[0109] Examples of cyan-based colorants include CI Solvent Blue 25, 36, 60, 70, 93, 95; CI Acid Blue 6, 45; CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, 16, 17, 17:1, 18, 22, 25, 56, 60, 63, 65, 66; CI Bat Blue 4, 60, and CI Pigment Green 7.

[0110] Examples of magenta-based colorants include CI Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 52, 58, 63, 81, 82, 83, 84, 100, 109, 111, 121, 122; CI Disperse Red 9; CI Solvent Violet 8, 13, 14, 21, 27; CI Disperse Examples include Violet 1; CI Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; CI Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28, etc. Furthermore, as magenta-based colorants, for example, CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 42, 48:1, Same 48:2, same 48:3, same 48:4, same 49, same 49:1, same 50, same 51, same 52, same 52:2, same 53:1, same 54, same 55, same 56, same 57:1, same 58, same 60, same 60:1, same 63, same 63:1, same 63:2, same 64, same 64:1, same 67, same 68, same 81, same 83, same 87, same 88, same 89, same 90, same 92, same 101 , 104, 105, 106, 108, 112, 114, 122, 123, 139, 144, 146, 147, 149, 150, 151, 163, 166, 168, 170, 171, 172, 175, 176, 177, 178, 179, 184, 185, 187, 190 Examples include 193, 202, 206, 207, 209, 219, 222, 224, 238, and 245; CI Pigment Violet 3, 9, 19, 23, 31, 32, 33, 36, 38, 43, and 50; CI Bat Red 1, 2, 10, 13, 15, 23, 29, and 35.

[0111] Examples of yellow colorants include CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162; CI Pigment Orange 31, 43; CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 24, 34, 35, 37, 42, 53, 55, 65, 73, 74. Examples include 75, 81, 83, 93, 94, 95, 97, 98, 100, 101, 104, 108, 109, 110, 113, 114, 116, 117, 120, 128, 129, 133, 138, 139, 147, 150, 151, 153, 154, 155, 156, 167, 172, 173, 180, 185, 195; CI Bat Yellow 1, 3, 20, etc.

[0112] As the above-mentioned coloring agent, from the viewpoint of excellent light-shielding properties of the decorative layer, a coloring agent that produces black is preferred, that is, it is preferable to include a coloring agent so that the decorative layer produces black. As the above-mentioned coloring agent that produces black, a black-based coloring agent may be used, which is a combination of the above-mentioned black-based coloring agent or a coloring agent that produces a color other than black and functions as a black-based coloring agent.

[0113] The decorative layer described above may contain other components besides those listed above, as long as they do not impair the effects of the present invention. Examples of these other components include crosslinking agents, curing agents, curing catalysts, crosslinking accelerators, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), anti-aging agents, fillers (metal powders, organic fillers, inorganic fillers, etc.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, rust inhibitors, granular materials, foil-like materials, flame retardants, silane coupling agents, and ion trapping agents. Each of these other components may be used individually or in combination of two or more.

[0114] The thickness of the decorative layer is preferably 0.01 to 50 μm, more preferably 0.05 to 35 μm, and even more preferably 0.1 to 20 μm. If the thickness of the decorative layer is 0.01 μm or more, the light-shielding properties are superior when light-shielding properties are present. If the thickness of the decorative layer is 50 μm or less, the difference in height between the adhesive layer and the decorative layer is small, resulting in a good appearance. If the decorative layer is composed of multiple layers (a single layer formed by the contact of multiple layers), the above thickness is the total thickness of the multiple layers.

[0115] (Laminated structure) The laminate of the present invention may include layers other than those described above. When the laminate of the present invention includes a substrate, it is preferable that the substrate and the adhesive layer are in contact in at least a portion (preferably the entire surface of one side of the substrate) (if a compatible layer is formed, it is considered to be in contact). Furthermore, when the laminate of the present invention includes a decorative layer, it is preferable that the adhesive layer and the decorative layer are in contact in at least a portion (preferably the entire surface of one side of the decorative layer).

[0116] When the laminate of the present invention includes a decorative layer, the haze value (H) of the region of the laminate of the present invention that does not have a decorative layer is not particularly limited, but from the viewpoint of suppressing image blurring in the OLED display device and displaying high-definition images, it is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. Furthermore, although not defining a lower limit, the above haze value may be 0.01% or more, or 0.05% or more. It is preferable that the above haze value of the laminate in which one end face is an adhesive layer and the other end face is a tack layer is within the above range, and it is also preferable that the above haze value of the laminate in which both end faces are adhesive layers is within the above range. Furthermore, if the laminate includes alkali-free glass or chemically strengthened glass as a base material and includes a decorative layer, it is preferable that the haze value of the laminate is within the above range, where one end face (for example, the end face of the one surface) is an adhesive layer or tack layer provided on one surface of the base material, and the other end face (for example, the end face of the other surface) is the base material, or an adhesive layer or tack layer provided on the other surface of the base material. Furthermore, if the laminate of the present invention does not include a decorative layer, it is preferable that the haze value of the laminate of the present invention is within the above range.

[0117] When the laminate of the present invention includes a decorative layer, the total light transmittance of the region of the laminate of the present invention that does not have a decorative layer is 85% or more, and from the viewpoint of ensuring the brightness of the OLED display device, 90% or more is preferable. Furthermore, the upper limit of the above total light transmittance is not particularly limited, but it may be less than 100%, 99.9% or less, or 99% or less. It is preferable that the total light transmittance of the laminate in which one end face is an adhesive layer and the other end face is a tack layer is within the above range, and it is also preferable that the total light transmittance of the laminate in which both end faces are adhesive layers is within the above range. Furthermore, when the substrate includes alkali-free glass or chemically strengthened glass and includes a decorative layer, it is preferable that the total light transmittance of the laminate in which one end face (for example, the end face of the one surface) is an adhesive layer or tack layer provided on one surface of the substrate, and the other end face (for example, the end face of the other surface) is the substrate, or an adhesive layer or tack layer provided on the other surface of the substrate is within the above range. Furthermore, if the laminate of the present invention does not include a decorative layer, the total light transmittance of the laminate of the present invention is preferably 85% or more, and more preferably within the above range.

[0118] When the laminate of the present invention includes a decorative layer, the total light transmittance of the region of the laminate of the present invention in which the decorative layer is laminated is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less, from the viewpoint of ensuring the concealment provided by the decorative layer. Furthermore, the lower limit of the above total light transmittance is not particularly limited, but may be, for example, 0.00001% or more, or 0.0001% or more. It is preferable that the above total light transmittance of the laminate in which one end face is an adhesive layer and the other end face is a tack layer is within the above range, and it is also preferable that the above total light transmittance of the laminate in which both end faces are adhesive layers is within the above range. Furthermore, if the laminate includes alkali-free glass or chemically strengthened glass as a base material and includes a decorative layer, it is preferable that the total light transmittance of the laminate is within the above range, where one end face (for example, the end face of the one surface) is an adhesive layer or tack layer provided on one surface of the base material, and the other end face (for example, the end face of the other surface) is the base material, or an adhesive layer or tack layer provided on the other surface of the base material.

[0119] The haze value and total light transmittance of the laminate of the present invention can be measured by the methods specified in JIS K7136 and JIS K7361, respectively, and can be controlled by the type and thickness of each layer constituting the laminate.

[0120] When the laminate of the present invention includes a decorative layer, the ratio of the thickness of the adhesive layer to the thickness of the decorative layer [thickness of adhesive layer:thickness of decorative layer] is preferably 1:0.01 to 1:100, more preferably 1:0.015 to 1:67, and even more preferably 1:0.02 to 1:50. If the thickness of the adhesive layer is greater than 1:100, the thickness of the adhesive layer is sufficient relative to the thickness of the decorative layer, resulting in superior adhesion of the decorative layer to the substrate. If the thickness of the decorative layer is less than 1:100, the difference in height between the adhesive layer and the decorative layer is small, resulting in a better appearance. If the thickness of the decorative layer is greater than 1:0.01, the light-shielding properties are superior if they are light-shielding. If the thickness of the adhesive layer is less than 1:0.01, the difference in height between the adhesive layer and the decorative layer is small, resulting in a better appearance. Note that if the adhesive layer and the decorative layer are each composed of multiple layers (a single layer formed by the contact of multiple layers), the above thickness is the total thickness of the multiple layers. Furthermore, in the above ratio, the adhesive layer and decorative layer are layers provided on the same side as the adhesive layer, that is, the thickness of the adhesive layer and decorative layer formed on one side of the adhesive layer (for example, the thickness of adhesive layer 3 and decorative layer 6 in Figures 8-9 or 13-14). Also, the thickness of the adhesive layer in the above ratio is the thickness of the adhesive layer located on the side opposite to the side on which the adhesive layer is laminated, that is, the thickness of the adhesive layer located between the surface of the adhesive layer opposite to the side on which the adhesive layer is laminated and the decorative layer. For example, if the adhesive layer covers the decorative layer as shown in Figure 10 or 15, it is the thickness of adhesive layer 3 located between the surface of adhesive layer 3 opposite to the side on which adhesive layer 2 is laminated and the decorative layer 6.

[0121] When the laminate of the present invention includes a decorative layer, the ratio of the total thickness of the adhesive layer and the decorative layer to the thickness of the adhesive layer [(thickness of adhesive layer + thickness of decorative layer):thickness of adhesive layer] is preferably 1:0.5 to 1:2500, more preferably 1:1 to 1:1500, and even more preferably 1:2 to 1:1000. If the thickness of the adhesive layer is greater than 1:0.5, it can adequately follow the steps between the adhesive layer and the decorative layer. If the thickness of the adhesive layer is less than 1:2500, it can further suppress adhesive overflow from the adhesive layer and blocking between laminates. Note that when the adhesive layer, decorative layer, and adhesive layer are each composed of multiple layers (a single layer formed by the contact of multiple layers), the above thickness is the total thickness of the multiple layers. Furthermore, the adhesive layer and decorative layer in the above ratio are layers provided on the same side as the adhesive layer, that is, the thickness of the adhesive layer and decorative layer formed on the one side (for example, the thickness of adhesive layer 3, decorative layer 6, and adhesive layer 2 in Figures 8-9 or 13-14). Also, the thickness of the adhesive layer in the above ratio is the thickness of the adhesive layer located on the side opposite to the side on which the adhesive layer is laminated, that is, the thickness of the adhesive layer located between the surface of the adhesive layer opposite to the side on which the adhesive layer is laminated and the decorative layer. For example, if the adhesive layer covers the decorative layer as shown in Figure 10 or 15, it is the thickness of adhesive layer 3 located between the surface of adhesive layer 3 opposite to the side on which adhesive layer 2 is laminated and the decorative layer 6. Furthermore, if the laminate comprises multiple adhesive layers, the adhesive layer in the above ratio refers to any one of the adhesive layers, which may be, for example, the adhesive layer with the greatest thickness.

[0122] The applications of the laminate of the present invention are not particularly limited and can be used for any application. Preferably, the laminate of the present invention is a laminate that can be used for optical applications, that is, for lamination on optical members (optical laminate). Examples of the optical members include electrical and electronic equipment. Note that "electrical and electronic equipment" refers to equipment that falls under at least one of electrical equipment or electronic equipment. Examples of the electrical and electronic equipment include image display devices such as liquid crystal displays, electroluminescent displays, and plasma displays, and portable electronic devices. Examples of the image display devices include image display devices in portable electronic devices, and displays (roll displays) inside and outside vehicles such as trains and buses.

[0123] Examples of the above-mentioned image display devices include liquid crystal displays, organic / inorganic electroluminescent displays, plasma displays, and OLED display panels. Examples of the above-mentioned image display devices include image display devices in portable electronic devices, in-vehicle displays, and digital signage (electronic billboards). The above-mentioned image display devices may be in a form (structure) such as a so-called "flexible type," or they may be in a form (structure) that can be bent or folded, such as a so-called "foldable type" or "rollable type."

[0124] Examples of the above-mentioned portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (for example, wristwear-type devices worn on the wrist like watches, modular devices attached to a part of the body with clips or straps, eyewear-type devices including glasses (monocular and binocular types, including head-mounted types), clothing-type devices attached to shirts, socks, hats, etc. as accessories, earwear-type devices attached to the ears like earphones, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game consoles, electronic dictionaries, electronic organizers, e-books, in-car information systems, portable radios, portable televisions, portable printers, portable scanners, and portable modems. In this specification, "portable" means not merely being able to carry something, but having a level of portability that allows an individual (a typical adult) to carry it relatively easily.

[0125] The optical components mentioned above specifically include, for example, components and modules that make up portable electronic devices, and housings for components and modules that make up portable electronic devices. More specifically, they include cover glass, lenses (especially glass lenses), touch panels, touch sensors such as touch sensor films (especially touch sensor films with metal wiring such as metal mesh films and silver nanowire films), polarizing films, display panels, sheet keyboards, protective panels for information display sections, housings, and decorative sheets. In this specification, a display panel refers to a structure that consists of at least a lens (especially a glass lens) and a touch panel. Furthermore, the term "lens" in this specification is a concept that includes both transparent materials that exhibit light refraction and transparent materials that do not exhibit light refraction. In other words, the term "lens" in this specification also includes simple window panels that do not exhibit light refraction.

[0126] The laminate of the present invention may include alkali-free glass or chemically strengthened glass with high flexibility as a substrate. Therefore, the laminate of the present invention is preferably used for lamination onto components in electrical and electronic equipment that is used in a bendable manner, such as a bendable substrate, such as a bendable image display device (flexible display) (especially a foldable image display device (foldable display)).

[0127] The laminate of the present invention is preferably used by being laminated onto an OLED display panel. The OLED display panel comprises at least an OLED element in which an anode, an OLED layer including an emissive layer, and a cathode are laminated in that order. The laminate of the present invention is laminated on the viewing side of the OLED element in the OLED display panel. An OLED display device in which the laminate of the present invention and the OLED display panel are laminated may be referred to as "the OLED display device of the present invention".

[0128] The laminate of the present invention is preferably a laminate used in an OLED display device in which only optical elements with a polarization degree of 95% or less are laminated on the viewing side of the OLED element (laminated for OLED display device). That is, the OLED display device of the present invention preferably has an OLED display panel in which only optical elements with a polarization degree of 95% or less are laminated on the viewing side of the OLED element. "Only optical elements with a polarization degree of 95% or less are laminated on the viewing side of the OLED element" means that the optical elements on the viewing side of the OLED element do not include optical elements with a polarization degree exceeding 95%. "Optical elements with a polarization degree exceeding 95%" are not particularly limited, but include polarizers such as linear polarizers, quarter phase difference plates, half phase difference plates, circular polarizers, and reflective polarizers. That is, the OLED display device of the present invention is preferably an OLED display device that does not include polarizers on the viewing side of the OLED element.

[0129] The degree of polarization is determined by the following formula, based on the parallel transmittance Tp and orthogonal transmittance Tc, which are measured using a UV-Vis spectrophotometer and corrected for luminous sensitivity. Polarization degree (%)={(Tp-Tc) / (Tp+Tc)}1 / 2×100

[0130] The OLED display device of the present invention, by not including a polarizing plate on the viewing side of the OLED element, suppresses the absorption of light emitted from the OLED element by the polarizing plate, improving light collection efficiency, saving power consumption, and extending the lifespan of the OLED element. Furthermore, the absence of a polarizing plate allows for a thinner design and reduces manufacturing costs.

[0131] [Method for manufacturing the laminated material of the present invention] The laminate of the present invention can be manufactured by a manufacturing method (manufacturing method (i)) comprising at least a step of forming an adhesive layer (adhesive layer forming step) and a step of directly forming an adhesive layer on the adhesive layer (direct adhesive layer forming step). The laminate of the present invention can also be manufactured by a manufacturing method (manufacturing method (ii)) comprising at least a step of forming an adhesive layer (adhesive layer forming step), forming an adhesive layer (adhesive layer forming step), and bonding the adhesive layer and the adhesive layer together (bonding step). The above manufacturing method may include a step of bonding a release liner to at least one surface of the laminate of the present invention. The above manufacturing method may also include a step of bonding a release liner to at least one surface of the adhesive layer and the adhesive layer.

[0132] Regarding the above manufacturing method (i), a method for manufacturing the laminate 1 shown in Figure 6 will be specifically described. Note that the manufacturing method described below is a preferred embodiment, and the manufacturing method for the laminate of the present invention is not limited to the above method.

[0133] (Adhesive layer formation process) In the above adhesive layer formation step, an adhesive layer 2 is formed on the release liner 42. The adhesive layer 2 can be manufactured, for example, by applying an adhesive composition for forming the adhesive layer 2 onto the release liner 42 and drying and curing the resulting adhesive composition layer, or by applying the adhesive composition onto the release liner and curing the resulting adhesive composition layer by irradiating it with active energy rays. If necessary, it may also be further heated and dried. If necessary, a release liner 43 may be bonded to the side of the adhesive layer 2 opposite to the side to which the release liner 42 is bonded, and then cured. Furthermore, if necessary, the release liner 42 and / or the release liner 43 may be peeled off, and another release liner may be bonded to the exposed adhesive surface.

[0134] Known coating methods may be used for applying (coating) the above adhesive composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, direct coaters, and die coaters may be used.

[0135] (Adhesive layer direct formation process) In the adhesive layer formation step described above, the adhesive layer 3 is directly formed on one surface of the adhesive layer 2. The adhesive layer can be formed on the adhesive layer 2 by known or conventional methods. The adhesive layer 3 can be manufactured, for example, by applying (coating) a composition for forming the adhesive layer 3 (adhesive composition) onto the adhesive layer 2 and drying and curing the resulting adhesive composition layer, or by applying (coating) the adhesive composition onto the adhesive layer 2 and curing the resulting adhesive composition layer by irradiating it with active energy rays. If a release liner is bonded to the surface of the adhesive layer 2, the release liner can be peeled off and the adhesive layer 3 can be formed on the exposed adhesive surface. In this way, the laminate 1 shown in Figure 6 can be manufactured. Furthermore, if necessary, it may be further heated and dried. The heating temperature at this time is not particularly limited, but for example, 50 to 150°C is preferred. When the adhesive layer 3 contains a heat-transferable resin or the same type of resin as the adhesive layer 2 (for example, acrylic polymer and acrylic polymer), heating the curing process allows a portion of the adhesive layer 3 to become compatible with a portion of the adhesive layer 2, thereby forming a compatible layer more efficiently.

[0136] A known coating method may be used for applying (coating) the above adhesive composition. For example, coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, spray coaters, comma coaters, and direct coaters may be used.

[0137] (Release liner application process) A release liner may be attached to the laminate of the present invention obtained as described above (release liner attachment step). The release liner may be attached to one side of the laminate of the present invention, or to both sides, or one release liner with both sides being release surfaces may be attached to one side.

[0138] The adhesive layer formation step in manufacturing method (ii) above can be carried out in the same manner as the adhesive layer formation step in manufacturing method (i) above. Furthermore, the adhesive layer formation step in manufacturing method (ii) above can be carried out in the same manner as the direct adhesive layer formation step in manufacturing method (i) above, except that the adhesive layer is formed on the release liner instead of directly on the adhesive layer. Furthermore, the bonding step in manufacturing method (ii) above can be performed by bonding the adhesive layer and the adhesive layer by a known or conventional method. In the bonding step above, if a release liner is bonded to the surfaces of the adhesive layer and the adhesive layer, the release liner can be peeled off and the exposed adhesive surface and the bonding surface can be bonded together. Heating (e.g., heat lamination, heat pressing) may be performed in the bonding step above if necessary. Furthermore, manufacturing method (ii) above may include the release liner application step in manufacturing method (i) above.

[0139] While alkali glass is commonly used for glass sheets, its hydrophilic surface allows for high adhesion of conventional adhesive layers to the glass. However, alkali-free glass and chemically strengthened glass, despite their high strength and flexibility even at thinness, have smooth and highly hydrophobic surfaces, making it difficult to adhere conventional adhesive layers to them with high flexibility. In contrast, the laminate of the present invention, by comprising adhesive layers and bonding layers with different elastic moduli, exhibits excellent adhesion even when the adherend is alkali-free glass or chemically strengthened glass, and is less likely to detach from alkali-free glass or chemically strengthened glass. Furthermore, it can follow bending and folding movements with high flexibility, is less prone to delamination or creases between layers, and exhibits excellent flexibility.

[0140] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. [Examples]

[0141] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples.

[0142] Example 1 (Preparation of acrylic prepolymer A solution) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 40 parts by mass of lauryl acrylate (LA), 57 parts by mass of 2-ethylhexyl acrylate (2EHA), 3 parts by mass of 4-hydroxybutyl acrylate (4HBA), 0.25 parts by mass of photoradical generator (trade name "Omnirad 819", manufactured by IGM Resins Italia Srl), and 0.05 parts by mass of photoradical generator (trade name "Omnirad 184", manufactured by IGM Resins Italia Srl) were added. Then, nitrogen gas was introduced, and nitrogen purging was performed for approximately 20 minutes while stirring. After that, 5 mW / cm² was added. 2 Polymerization was carried out by irradiating with ultraviolet light, and the reaction rate was adjusted to 5-15% to obtain acrylic prepolymer solution A.

[0143] (Preparation of adhesive composition) To the above acrylic prepolymer A solution, 0.1 parts by mass of dipentaerythritol hexaacrylate (DPHA) as a crosslinking agent and 0.3 parts by mass of 3-glycidyloxypropyltrimethoxysilane as a silane coupling agent were added and stirred to prepare an adhesive composition.

[0144] (Formation of the adhesive layer) The above adhesive composition was applied to the release-treated surface of a release liner (product name "MRE38," manufactured by Mitsubishi Chemical Corporation, a polyethylene terephthalate film with a release treatment on one side, 38 μm thick) to form an adhesive composition layer, and the release-treated surface of a release liner (product name "MRF38," manufactured by Mitsubishi Chemical Corporation) was bonded onto this adhesive composition layer. Next, a black light was used to measure 2.5 mW / cm². 2 The ultraviolet light at an illuminance of 2400 mJ / cm² is measured by the cumulative light intensity of 2400 mJ / cm². 2 Polymerization was carried out by irradiation until the desired result was obtained, yielding an adhesive layer (optically transparent adhesive sheet) with a thickness of 40 μm.

[0145] (Preparation of adhesive composition) An epoxy solution was prepared by mixing 50 parts by mass of 1,2-epoxy-4-(2-oxyranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (trade name "Celoxide EHPE3150", manufactured by Daicel Corporation) and 50 parts by mass of ethyl acetate as epoxy polymers and stirring. To the above epoxy solution, a methyl ethyl ketone solution of acrylic resin (solids content 40% by weight, trade name "KRM-9322", manufactured by Daicel Ornex Corporation) was added so that the solids content was 50 parts by mass and the mixture was stirred. To this solution, 5 parts by mass of diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate (trade name "CPI-110P", manufactured by Sunapro Co., Ltd.) as a photoacid generator, 1 part by mass of a photoradical generator (trade name "Omnirad 651", manufactured by IGM Resins Italia Srl), 1 part by mass of another photoradical generator (trade name "Omnirad 184", manufactured by IGM Resins Italia Srl), and 428 parts by mass of ethyl acetate were added and stirred to obtain an adhesive composition.

[0146] (Preparation of adhesive sheets) After peeling off one of the release liners from the adhesive layer, the adhesive composition was applied to the exposed adhesive surface of the adhesive layer to form an adhesive composition layer, and dried at 80°C for 1 minute to form an adhesive layer with a thickness of 2 μm. The release treated surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation) was bonded to the surface of the adhesive layer thus formed to obtain a sheet (adhesive sheet) in which one side was the adhesive layer surface and the other side was the adhesive layer surface.

[0147] Examples 2-3 Adhesive sheets for each example were prepared in the same manner as in Example 1, except that the composition of the adhesive layer was changed as shown in Table 1.

[0148] Comparative Example 1 A comparative adhesive sheet was prepared in the same manner as in Example 1, except that an adhesive layer was not formed.

[0149] Example 4 (Preparation of acrylic prepolymer B solution) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 24 parts by mass of lauryl acrylate (LA), 16 parts by mass of butyl acrylate (BA), 57 parts by mass of n-octyl acrylate (NOAA), 3 parts by mass of 4-hydroxybutyl acrylate (4HBA), 0.05 parts by mass of photoradical generator (trade name "Omnirad 127D", manufactured by IGM Resins Italia Srl), and 0.05 parts by mass of photoradical generator (trade name "Omnirad 2959", manufactured by IGM Resins Italia Srl) were added. Then, nitrogen gas was introduced, and nitrogen purging was performed for approximately 20 minutes while stirring. After that, 5 mW / cm² was added. 2 Polymerization was carried out by irradiating with ultraviolet light, and the reaction rate was adjusted to 5-15% to obtain acrylic prepolymer solution B.

[0150] (Preparation of acrylic polymer C) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, a mixture containing 60 parts by mass of dicyclopentanyl methacrylate (DCPMA), 40 parts by mass of methyl methacrylate (MMA), 3 parts by mass of a chain transfer agent (α-thioglycerol), 0.3 parts by mass of a thermal polymerization initiator (azobisisobutyronitrile), and a solvent (ethyl acetate) (solid content 26% by mass) was added. Then, nitrogen gas was introduced, and the mixture was purged with nitrogen while stirring for about 20 minutes. The reaction was then carried out at 72°C to 74°C for 6 hours (polymerization reaction). Next, the reaction solution was heated at 90°C for 12 hours to volatilize and remove ethyl acetate, the chain transfer agent, and unreacted monomers, thereby obtaining acrylic polymer C.

[0151] (Preparation of adhesive composition) To the above acrylic prepolymer B solution, 0.5 parts by mass of the above acrylic polymer C, 0.1 parts by mass of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent, 10 parts by mass of lauryl acrylate as an additional acrylic monomer, and 0.3 parts by mass of 3-glycidyloxypropyltrimethoxysilane as a silane coupling agent were added and stirred to prepare an adhesive composition.

[0152] (Formation of the adhesive layer) An adhesive layer (optically transparent adhesive sheet) was obtained in the same manner as in Example 1, except that the adhesive composition prepared above was used.

[0153] (Preparation of adhesive composition) An adhesive composition was obtained in the same manner as in Example 1.

[0154] (Preparation of adhesive sheets) The above adhesive composition was applied to the release-treated surface of a release liner (product name "MRE38", manufactured by Mitsubishi Chemical Corporation, polyethylene terephthalate film with release treatment on one side, thickness 38 μm) to form an adhesive composition layer, and dried at 80°C for 1 minute to form an adhesive layer with a thickness of 2 μm. Next, after peeling off one side of the release liner of the adhesive layer obtained above, the adhesive layer was bonded to the exposed adhesive surface of the adhesive layer to obtain a sheet (adhesive sheet) in which one side is the adhesive layer surface and the other side is the adhesive layer surface.

[0155] Examples 5-9 Each example of adhesive sheet was prepared in the same manner as in Example 4, except that the composition of the adhesive layer and the bonding layer was changed as shown in Tables 2 and 3.

[0156] Comparative Example 2 A comparative adhesive sheet was prepared in the same manner as in Example 4, except that an adhesive layer was not formed.

[0157] Comparative Example 3 A comparative adhesive sheet was prepared in the same manner as in Example 6, except that an adhesive layer was not formed.

[0158] The components shown in Tables 1-3 are as follows: <Thermal transfer resin> EHPE3150: Product name "Celoxide EHPE3150", manufactured by Daicel Corporation, curable epoxy resin (epoxy polymer) KRM-9322: Product name "KRM-9322", manufactured by Daicel Ornex Co., Ltd., acrylic resin acrylate (acrylic polymer) BR-83: Product name "BR-83", manufactured by Mitsubishi Chemical Corporation, methacrylic resin (acrylic polymer) UN-954: Product name "UN-954", manufactured by Negami Kogyo Co., Ltd., urethane acrylate resin (urethane polymer)

[0159] <Additives> DPHA: Dipentaerythritol hexaacrylate, crosslinking agent NDDA: 1,9-nonanediol diacrylate, crosslinking agent CPI-110P: Product name "CPI-110P", manufactured by Sunapro Co., Ltd., diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate, photoacid generator Omnirad 184: Product name "Omnirad 184", manufactured by IGM Resins Italia Srl, photoradical generator. Omnirad 651: Product name "Omnirad 651", manufactured by IGM Resins Italia Srl, photoradical generator.

[0160] [evaluation] The following evaluations were performed on the adhesive sheets and bonding sheets obtained in the examples and comparative examples, and the results are shown in Tables 1 to 3.

[0161] (1) Total light transmittance The release liner from the adhesive layer of the adhesive sheet was peeled off and bonded to alkali-free glass (product name "Eagle XG", 40 mm long, 50 mm wide, 0.7 mm thick, manufactured by Corning). This was then subjected to heating and pressurizing treatment at 50°C, 0.5 MPa for 15 minutes to ensure adhesion. Next, the remaining release liner was peeled off to obtain a test specimen. The total light transmittance of the test specimen was measured from the alkali-free glass side using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Laboratory Co., Ltd.).

[0162] (2) Elastic modulus The adhesive layers in Examples 1-5 and Comparative Examples 1-2 are UV-curable (ultraviolet curable). Since the shear modulus was not properly measured due to the high elastic modulus of the UV-cured adhesive layers, the tensile modulus was used for these UV-cured adhesive layers.

[0163] (2-1) Shear modulus (G') A 1.0-2.0 mm thick sheet was created by laminating an adhesive layer or an uncured adhesive layer, and then punched out into an 8 mm diameter disc to be used as the measurement sample. During lamination, the adhesive layer or adhesive layer was heated to 50°C as needed. The shear modulus was measured using a rheometer (product name "ARES-G2", manufactured by TA Instruments) in torsion mode, with a measurement frequency of 1 Hz, a measurement temperature of -50 to 150°C, and a heating rate of 5°C / min. Furthermore, even below 150°C, the shear modulus was measured to be 10 3 If the reading fell below Pa, the measurement was terminated at that point. In this manner, the shear modulus of the adhesive layer (G1') and the shear modulus of the adhesive layer before UV curing (G2') were measured.

[0164] (2-2) Tensile modulus (E') Adhesive layers were laminated before UV curing to form adhesive sheets with a thickness of 10-100 μm. The fabricated adhesive sheets were sandwiched between two release liners and subjected to UV-LED irradiation using a UV-LED device (product name "QEL-350-RU6W-CW-MY", manufactured by Quark Technology Inc.) with a 365 nm wavelength UV-LED lamp as the light source, and the integrated irradiation intensity was 2 J / cm². 2 UV irradiation was performed to achieve the desired result. After cutting the cured adhesive layer into pieces measuring 5 mm wide x 50 mm long, the release liner was removed from both sides. Next, dynamic viscoelasticity was measured using a rheometer (product name "RSA G2", manufactured by TA Instruments) under the conditions of a frequency of 1 Hz, a heating rate of 5 °C / min, and a measurement temperature of -50 to 150 °C. In this manner, the tensile modulus (E2') of the UV-cured adhesive layer was measured.

[0165] (3) Glass transition temperature The adhesive layers in Examples 1-5 and Comparative Examples 1-2 are UV-curable (ultraviolet curable). Since the adhesive layers after UV curing have a high elastic modulus, and it was not possible to properly measure tanδ by measuring the shear modulus, the tanδ measured by the tensile modulus was used for these UV-cured adhesive layers.

[0166] (3-1) Glass transition temperature (torsion mode) A 1.0-2.0 mm thick layer of adhesive or uncured adhesive was laminated and punched out as an 8 mm diameter disc, which was used as the measurement sample. During lamination, the adhesive or uncured adhesive layer was heated to 50°C as needed. The loss tangent (tanδ) was measured using a rheometer (product name "ARES-G2", manufactured by TA Instruments) in torsion mode, with a measurement frequency of 1 Hz, a measurement temperature of -50 to 170°C, and a heating rate of 5°C / min. In this way, the tanδ of the adhesive layer and the uncured adhesive layer were measured, and their respective peak temperatures were defined as the glass transition temperatures.

[0167] (3-2) Glass transition temperature (measured in tensile mode) Adhesive layers were laminated before UV curing to form adhesive sheets with a thickness of 10-100 μm. The fabricated adhesive sheets were sandwiched between two release liners and subjected to UV-LED irradiation using a UV-LED device (product name "QEL-350-RU6W-CW-MY", manufactured by Quark Technology Inc.) with a 365 nm wavelength UV-LED lamp as the light source, and the integrated irradiation intensity was 2 J / cm². 2 UV irradiation was performed to achieve the desired result. After cutting the cured adhesive layer into 5mm wide x 50mm long pieces, the release liner was removed from both sides. Next, the loss tangent (tanδ) was measured in tensile mode using a rheometer (product name "RSA G2", manufactured by TA Instruments) under the conditions of frequency 1Hz, heating rate 5℃ / min, and measurement temperature -50 to 170℃. The tanδ of the UV-cured adhesive layer was measured in the above manner, and the respective peak temperatures were defined as the respective glass transition temperatures.

[0168] (4-1) 180° peel strength under room temperature conditions Under a measurement environment of 23°C and 50% RH, test specimens were prepared by cutting the adhesive sheets prepared in the Examples and the Comparative Example to a size of 25 mm in width and 100 mm in length. For the prepared test specimens, the release liner on the adhesive layer surface of the Example specimen was peeled off, and it was bonded to the surface of alkali-free glass (product name "Eagle XG", 100 mm in length, 100 mm in width, 0.7 mm in thickness, manufactured by Corning) as the adherend, and pressed down with a 2 kg roller for one pass. Similarly, one release liner was peeled off the Comparative Example specimen, and the exposed adhesive layer surface was bonded to the surface of the alkali-free glass, and pressed down with a 2 kg roller for one pass. These were then subjected to a heating and pressurizing treatment at 50°C, 0.5 MPa for 15 minutes to ensure adhesion. Next, the remaining release liner was peeled off, and a 50 μm thick PET film was bonded to the backing. Next, using a UV-LED irradiation device (product name "QEL-350-RU6W-CW-MY", manufactured by Quark Technology Inc.), a UV-LED lamp with a wavelength of 365 nm was used as the light source, and the integrated irradiation light dose was 2 J / cm². 2Ultraviolet irradiation was performed to achieve the desired result. After leaving the sample in the same environment for 24 hours, the 180° peel force (adhesion force) [N / 25mm] at room temperature was measured using a universal tensile and compression testing machine in accordance with JIS Z 0237:2000, under conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees. A universal tensile and compression testing machine (device name "TG-1kN", manufactured by MinebeaMitsumi Inc.) was used.

[0169] (4-2) 180° peeling force under heating conditions The 180° peel strength under heated conditions was determined using the same procedure as for the 180° peel strength under room temperature conditions, except that the procedure after UV irradiation was modified as follows. After being left in an environment of 23°C and 50%RH for 24 hours, the samples were moved to an environment of 60°C and 10%RH and left for 30 minutes. Then, under the same conditions, a universal tensile and compression tester was used to measure the 180° peel strength (adhesion strength) [N / 25mm] under heated conditions, in accordance with JIS Z 0237:2000, at a tensile speed of 300 mm / min and a peel angle of 180 degrees.

[0170] [Table 1]

[0171] As shown in Table 1, the adhesive sheets of Examples 1 to 3 were confirmed to have high 180° peel strength against alkali-free glass, and were evaluated as having high adhesion to alkali-free glass and being less prone to peeling. On the other hand, the adhesive sheet of the comparative example, which did not have an adhesive layer, had low 180° peel strength and was evaluated as having poor adhesion to alkali-free glass.

[0172] [Table 2]

[0173] As shown in Table 2, the adhesive sheets of Examples 4-5 were confirmed to have high 180° peel strength against alkali-free glass, and were evaluated as having high adhesion to alkali-free glass and being less prone to peeling. On the other hand, the adhesive sheet of the comparative example, which did not have an adhesive layer, had low 180° peel strength and was evaluated as having poor adhesion to alkali-free glass.

[0174] [Table 3]

[0175] As shown in Table 3, the adhesive sheets of Examples 6-9 were confirmed to have high 180° peel strength against alkali-free glass, and were evaluated as having high adhesion to alkali-free glass and being less prone to peeling. On the other hand, the adhesive sheet of the comparative example, which did not have an adhesive layer, had low 180° peel strength and was evaluated as having poor adhesion to alkali-free glass.

[0176] The following describes variations of the invention relating to this disclosure. [Note 1] The laminate comprises an adhesive layer and an adhesive layer laminated on at least one surface of the adhesive layer. The total light transmittance of the laminate is 85% or more. A laminate in which the ratio of the elastic modulus of the adhesive layer at 25°C to the elastic modulus of the adhesive layer at 25°C [elastic modulus of the adhesive layer at 25°C / elastic modulus of the adhesive layer at 25°C] is 2 or more. [Note 2] The laminate as described in Note 1, wherein the ratio of the thickness of the adhesive layer to the thickness of the bonding agent layer is 1:0.0001 to 1:1. [Note 3] The laminate according to Note 1 or 2, wherein the glass transition temperature of the adhesive layer is 0 to 180°C. [Note 4] The laminate according to any one of Notes 1 to 3, wherein the difference between the glass transition temperature of the adhesive layer and the glass transition temperature of the adhesive layer [(glass transition temperature of the adhesive layer) - (glass transition temperature of the adhesive layer)] is 50 to 220°C. [Note 5] The elastic modulus of the adhesive layer at 25°C is 103 ~10 6 A laminate described in any one of the appendices 1 to 4, which is Pa. [Note 6] The laminate according to any one of Notes 1 to 5, wherein a release liner is bonded to at least one surface of the laminate. [Explanation of symbols]

[0177] 1. Laminate 2,21,22 Adhesive layer 3,31,32 Adhesive layer 4,41,42 Peel-off liner 5 Base material 6. Decorative layer

Claims

1. A laminate comprising an adhesive layer and an adhesive layer laminated on at least one surface of the adhesive layer, The total light transmittance of the laminate is 85% or more. A laminate in which the ratio of the elastic modulus of the adhesive layer at 25°C to the elastic modulus of the adhesive layer at 25°C [elastic modulus of the adhesive layer at 25°C / elastic modulus of the adhesive layer at 25°C] is 2 or more.

2. The laminate according to claim 1, wherein the ratio of the thickness of the adhesive layer to the thickness of the bonding agent layer is 1:0.0001 to 1:

1.

3. The laminate according to claim 1 or 2, wherein the glass transition temperature of the adhesive layer is 0 to 180°C.

4. The laminate according to claim 1 or 2, wherein the difference between the glass transition temperature of the adhesive layer and the glass transition temperature of the tack layer [(glass transition temperature of the adhesive layer) - (glass transition temperature of the tack layer)] is 50 to 220°C.

5. The elastic modulus of the adhesive layer at 25°C is 10 ３ ~10 ６ The laminate according to claim 1 or 2, wherein the material is Pa.

6. The laminate according to claim 1 or 2, wherein a release liner is bonded to at least one surface of the laminate.

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