Laminate

Abstract

To provide a novel laminate that does no impair the visibility of design of a decorative film.SOLUTION: There is provided a laminate. In the laminate, a transparent member, an adhesive layer, and a decorative film are disposed in the stated order.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminate, and more particularly to a laminate including a decorative film. [Background technology]

[0002] Decorative films such as metallic films are used for the purpose of imparting design to various applications such as portable electronic devices such as smartphones, tablet computers, and laptop computers, and vehicle cover members. Such decorative films have designs including color, color tone, patterns, and the like on their surfaces (decorated surfaces). For example, highly functional decorative films that have electromagnetic wave transparency in addition to metallic luster as the design have been proposed recently. Patent Document 1 is an example of a prior art document that discloses this type of conventional technology.

[0003] Meanwhile, adhesives (also called pressure-sensitive adhesives; the same applies below) are widely used in various industrial fields as a means for bonding films and members. Adhesives are soft solid (viscoelastic) in a temperature range around room temperature, and have the property of easily adhering to an adherend by pressure. In addition to the above-mentioned adhesive properties, they may have one or more properties suitable for various applications. For example, adhesives used for optical applications may have excellent transparency and visibility through the adhesive in addition to adhesive properties to members. Examples of prior art documents disclosing this type of conventional technology include Patent Documents 2 and 3. Patent Document 4 is a prior art document disclosing a shatterproof adhesive sheet that is attached to the cover glass of a capacitive touch panel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-69462 A [Patent Document 2] Patent No. 4673344 [Patent Document 3] Patent No. 4805999 [Patent Document 4] Patent No. 6251801 Summary of the Invention [Problem to be solved by the invention]

[0005] The conventional decorative film is used by placing the back surface of the decorative film on the surface of the substrate, and the decorative surface (front surface) of the decorative film is usually placed on the outermost surface. In such a case, the decorative film needs to have a certain durability against external forces and in the usage environment. Alternatively, a method of improving durability by providing a protective layer on the surface of the decorative film is considered, but the design of the decorative film is likely to be reduced, and the formation of such a protective layer increases the number of steps, increases the thickness, and increases costs, which is disadvantageous in terms of productivity.

[0006] The present invention has been created in view of the above circumstances, and has an object to provide a novel laminate that does not impair the visibility of the design of a decorative film. [Means for solving the problem]

[0007] According to this specification, a laminate is provided in which a transparent member, an adhesive layer, and a decorative film are arranged in this order. With this laminate, the design (including color, tone, pattern, and even text information such as a logo mark; the same applies below) on the surface of the decorative film can be seen through the transparent member and the adhesive layer. In addition, due to the presence of the decorative film, the laminate as a whole can have concealing properties (internal concealing properties when the transparent member side is considered to be the outside).

[0008] In some preferred embodiments, the visible light transmittance in the lamination direction of the transparent member, the adhesive layer, and the decorative film is less than 10%. The laminate thus constructed can exhibit good concealment while exhibiting the design of the decorative film. For example, when the transparent member of the laminate is used as a housing for a structure such as a portable electronic device, the inside of the structure is concealed, while the design of the decorative film can be seen through the transparent member on the outer surface.

[0009] In some preferred embodiments, the pressure-sensitive adhesive layer surface has an arithmetic mean roughness Ra of 70 nm or less and a maximum height Rz of 600 nm or less. By using such a pressure-sensitive adhesive layer with high surface smoothness, the design of the decorative film surface can be more clearly seen through the pressure-sensitive adhesive layer.

[0010] In some preferred embodiments, the pressure-sensitive adhesive layer has a total light transmittance of 85% or more in the lamination direction and a haze value of 1% or less. With a pressure-sensitive adhesive layer that satisfies the above characteristics, the design on the surface of the decorative film can be more clearly seen through the pressure-sensitive adhesive layer. In some embodiments, the laminated structure of the transparent member and the pressure-sensitive adhesive layer has a total light transmittance of 85% or more in the lamination direction and a haze value of 1% or less. With a transparent member and pressure-sensitive adhesive layer that satisfy the above characteristics, the design on the surface of the decorative film can be more clearly seen through the transparent member and the pressure-sensitive adhesive layer.

[0011] In some preferred embodiments, the pressure-sensitive adhesive layer has a storage modulus of 4×10 at 25° C. 4 The pressure-sensitive adhesive layer having the above storage modulus at 25° C. tends to have favorable heat resistance, and is likely to exhibit favorable adhesive properties such as deformation resistance.

[0012] In some preferred embodiments, the pressure-sensitive adhesive layer is adhered to the transparent member with a 180-degree peel strength of more than 7 N / 20 mm. By providing good adhesion between the transparent member and the pressure-sensitive adhesive layer in this manner, the laminate can exhibit good durability against impacts and the like.

[0013] In some preferred embodiments, the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer.Acrylic pressure-sensitive adhesives can achieve the desired adhesive and viscoelastic properties without using additives such as softeners that may cause a decrease in transparency, or by limiting the amount of additives used, so that transparency, adhesive and viscoelastic properties can be easily achieved.In addition, acrylic pressure-sensitive adhesives tend to have better color fastness than rubber pressure-sensitive adhesives, for example, and are also advantageous in terms of maintaining transparency over a long period of time.

[0014] In some preferred embodiments, the pressure-sensitive adhesive layer has a modulus of elasticity of 3.0 MPa or more as measured by the tensile test described below. By satisfying the above characteristics, the pressure-sensitive adhesive layer can exhibit high resistance to deformation. [Tensile test] The adhesive layer was exposed to an illumination intensity of 300 mW / cm 2 , cumulative light intensity 3000mJ / cm 2 After aging at 50° C. for 48 hours, the pressure-sensitive adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test piece. A tensile test is performed on the test piece using a tensile tester under conditions of 23° C., 50% RH, 120 mm between-chuck distance, and 50 mm / min tensile speed to obtain a stress-displacement curve, and the elastic modulus [MPa] is calculated from the initial slope.

[0015] In some preferred embodiments, the pressure-sensitive adhesive layer has an impact resistance of 2.0 J / 10 mm as measured by the following shear impact test. 2 That's all. By satisfying the above characteristics, the pressure-sensitive adhesive layer can exhibit high impact resistance. For example, a pressure-sensitive adhesive layer that satisfies the elastic modulus characteristics and the impact resistance characteristics in the tensile test can form a bond that is highly resistant to deformation and highly resistant to impact, so that a laminate including the pressure-sensitive adhesive layer can also have excellent deformation resistance and impact resistance. [Shear impact test] A shear impact test is performed using a pendulum-type adhesive shear impact tester based on JIS K6855. As a measurement sample, the first surface of the pressure-sensitive adhesive layer, which is 10 mm square, is attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then the second surface of the pressure-sensitive adhesive layer is attached to the center of a 40 mm square stainless steel plate (SUS304BA plate) and pressed with a load of 5 N for 10 seconds, and then autoclaved (50°C, 0.5 MPa, 15 minutes), and the illuminance from the glass plate side is 300 mW / cm. 2 , cumulative light intensity 3000mJ / cm 2 After irradiating ultraviolet light under the above conditions, the film is aged at 50°C for 48 hours before use. The measurement sample was fixed so that the stainless steel plate was on the bottom side, and a hammer was applied to the outer peripheral side of the glass plate at a hammer energy of 2.75 J and a hammer speed of 3.5 m / sec in an environment of 23°C and 50% RH. The absorbed energy [J] was measured to determine the impact resistance [J / 10 mm 2 ] is required.

[0016] In some preferred embodiments, the pressure-sensitive adhesive layer contains a polymer (A) and a photoreactive monomer (B). The photoreactive monomer (B) contains a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule, and the compound B1 more preferably has a molecular weight of 100 g / mol or more per ethylenically unsaturated group. The pressure-sensitive adhesive layer can suitably form a bond with high deformation resistance and high impact resistance, so that a laminate including the pressure-sensitive adhesive layer can also have excellent deformation resistance and impact resistance.

[0017] In some preferred embodiments, the decorative film has a base layer and a decorative layer covering at least a part of at least one surface of the base layer. The thickness of the decorative layer is within the range of 1 to 1000 nm. By incorporating a decorative film having such a thin decorative layer into the laminate disclosed herein, the surface of the decorative film is protected by the transparent member and the adhesive layer, and deterioration such as discoloration and peeling is prevented.

[0018] In some preferred embodiments, the sheet resistance of the decorative layer is 100 Ω / □ or more. A decorative film having such a decorative layer can have radio wave transparency, and can therefore be preferably used in various applications requiring radio wave transparency, such as portable electronic devices.

[0019] In some embodiments, the transparent member has a linearly bent portion or a curved portion that curves in a curved line in any cross section parallel to the stacking direction of the laminate. The adhesive layer and the decorative film are disposed at the bent portion or the curved portion of the transparent member. According to the technology disclosed herein, in a configuration including a transparent member having a bent portion or a curved portion as described above, the design of the decorative film surface can be clearly seen through the transparent member and the adhesive layer.

[0020] The laminate according to some embodiments further has one or more colored layers. The colored layers are disposed between the transparent member and the adhesive layer, between the adhesive layer and the decorative film, or on the side of the decorative film opposite to the adhesive layer. With such a laminate structure, the presence of the colored layers can provide higher concealment properties.

[0021] The laminate according to some embodiments can be preferably used in a portable electronic device. For example, by using the transparent member disclosed herein as a transparent (including translucent) housing, a structure can be constructed in which a decorative film is fixed to the inside of the housing. Such a structure can be particularly suitable as an exterior structure such as a case, since the design of the decorative film can be visually recognized from the outside while having internal concealment properties. Furthermore, since the laminate can have radio wave transparency depending on the selection of the decorative film, it can be preferably used as a laminate for a portable electronic device. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a laminate according to one embodiment. [Diagram 2]FIG. 4 is a schematic cross-sectional view showing a laminate according to another embodiment. [Diagram 3] FIG. 4 is a schematic cross-sectional view showing a laminate according to another embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a laminate according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] A preferred embodiment of the present invention will be described below. Note that matters other than those specifically mentioned in this specification and necessary for carrying out the present invention can be understood by a person skilled in the art based on the teachings on carrying out the invention described in this specification and the common general knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the common general knowledge in the field. In addition, in the following drawings, components and parts having the same function may be described by using the same reference numerals, and duplicated descriptions may be omitted or simplified. In addition, the embodiments described in the drawings are schematic in order to clearly explain the present invention, and do not necessarily accurately represent the size or scale of the product actually provided.

[0024] In this specification, the term "adhesive" refers to a material that exhibits a soft solid (viscoelastic) state at temperatures near room temperature and that has the property of easily adhering to an adherend by pressure, as described above. The adhesive referred to here is generally a material having a complex tensile modulus E * (1Hz)<10 7 dyne / cm 2 The material may be a material having the properties satisfying the above (typically, a material having the above properties at 25°C).

[0025] In this specification, "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight of an acrylic monomer, and is also called an acrylic polymer. The acrylic monomer refers to a monomer derived from a monomer having at least one (meth)acryloyl group in one molecule. In addition, in this specification, "(meth)acryloyl" refers to acryloyl and methacryloyl in a comprehensive sense. Similarly, "(meth)acrylate" refers to acrylate and methacrylate, and "(meth)acrylic" refers to acrylic and methacrylic in a comprehensive sense. In this specification, the terms "mass" and "weight" are synonymous.

[0026] In this specification, the "photoreactive monomer" is a compound having at least one functional group (photoreactive functional group) in the molecule that can undergo a reaction by irradiation with light, and typically a compound having at least one ethylenically unsaturated group in the molecule as the photoreactive functional group. The photoreactive monomer referred to here may be any monomer that can cause a reaction as a monomer, and may be, for example, a polymer such as an oligomer or polymer (for example, a polymer having at least one ethylenically unsaturated group in the molecule).

[0027] <Example of laminate configuration> FIG. 1 shows an example of the structure of the laminate disclosed herein. The laminate 1 is a laminate in which a transparent member 10, a pressure-sensitive adhesive layer 20, and a decorative film 30 are arranged in this order. The pressure-sensitive adhesive layer 20 has a first adhesive surface 20a and a second adhesive surface 20b on the opposite side to the first adhesive surface 20a. The transparent member 10 is bonded to the pressure-sensitive adhesive layer 20, and specifically, the pressure-sensitive adhesive layer side surface (second surface) 10b of the transparent member 10 is bonded to the first adhesive surface 20a of the pressure-sensitive adhesive layer 20. The opposite side (first surface) 10a of the pressure-sensitive adhesive layer side surface 10b of the transparent member 10 constitutes the outer surface of the laminate 1. The pressure-sensitive adhesive layer 20 is also bonded to the decorative film 30. Specifically, the second adhesive surface 20b of the pressure-sensitive adhesive layer 20 is bonded to one surface (first surface) 30a of the decorative film 30. In this embodiment, the surface 30a of the decorative film is a decorative surface.

[0028] FIG. 2 shows a schematic structure of a laminate according to another embodiment. The laminate 2 shown in FIG. 2 differs from the laminate 1 shown in FIG. 1 in that a colored layer 40 is disposed between the transparent member 10 and the adhesive layer 20. In this embodiment, the colored layer 40 is partially formed on the second surface 10b of the transparent member 10. Therefore, the colored layer 40 protrudes from the second surface 10b of the transparent member 10 by the thickness of the colored layer 40, and the adhesive layer 20 side of the transparent member 10 including the colored layer 40 has a step as a whole. The first adhesive surface 20a of the adhesive layer 20 follows and adheres to such a step-forming surface. The other points are basically the same as those shown in FIG. 1, so a duplicated description will be omitted here.

[0029] FIG. 3 is a schematic diagram showing the structure of a laminate according to yet another embodiment. The laminate 3 shown in FIG. 3 is different from the laminate 2 shown in FIG. 2 in that the laminate 3 has a colored layer 50 below the decorative film 30 (the side opposite to the adhesive layer 20). That is, the laminate 3 is a laminate in which a transparent member 10, an adhesive layer 20, a decorative film 30, and a colored layer 50 are arranged in this order. In addition, in the laminate 3, a colored layer (partially arranged colored layer) 40 is also arranged between the transparent member 10 and the adhesive layer 20, as in the laminate 2. In this embodiment, the colored layer 50 is arranged on the second surface 30b of the decorative film 30 (the surface opposite to the first surface 30a on the adhesive layer 20 side). More specifically, the colored layer 50 is arranged on the entire second surface 30b of the decorative film 30. The colored layer 50 in this embodiment is a black layer, and the laminate 3 has concealment properties in the lamination direction. Other points are basically the same as those in the configuration shown in FIG. 2, so a duplicated description will be omitted here.

[0030] The structure of a laminate according to yet another embodiment is shown in FIG. 4. The laminate 4 shown in FIG. 4 has a second adhesive layer 60 below the decorative film 30 (the side opposite to the first adhesive layer 20), and further has a colored layer 50 below the second adhesive layer 60 (the side opposite to the decorative film 30). This is different from the laminate 3 shown in FIG. 3. That is, the laminate 4 is a laminate in which the transparent member 10, the first adhesive layer 20, the decorative film 30, the second adhesive layer 60, and the colored layer 50 are arranged in this order. In addition, in the laminate 4, a colored layer (partially arranged colored layer) 40 is also arranged between the transparent member 10 and the adhesive layer 20, similar to the laminate 3. In this embodiment, the first adhesive surface 60a of the second adhesive layer 60 is adhered to the second surface 30b of the decorative film 30, and the second adhesive surface 60b of the second adhesive layer 60 is adhered to the colored layer 50. The second pressure-sensitive adhesive layer 60 and the colored layer 50 may be a single-sided adhesive sheet with a colored substrate. The thickness of the second pressure-sensitive adhesive layer 60 is greater than the thickness of the first pressure-sensitive adhesive layer 20. The colored layer 50 is disposed over the entire second surface 60b of the second pressure-sensitive adhesive layer 60, similar to the configuration shown in FIG. 3. The colored layer 50 in this embodiment is a black layer, and the laminate 4 has concealment properties in the lamination direction. Other points are basically the same as the configuration shown in FIG. 3, so duplicated explanations will be omitted here.

[0031] In the configurations shown in FIGS. 2 to 4, the colored layer 40 is partially provided on the second surface 10b of the transparent member 10, but this is not limited thereto. The partially-arranged colored layer may be provided in a recess formed in the second surface of the transparent member. This allows the colored layer partially provided on the second surface of the transparent member not to protrude from the second surface. Alternatively, the partially-arranged colored layer may be partially formed on the first adhesive surface of the adhesive layer. Such a colored layer may also be arranged on the second surface of the adhesive layer.

[0032] 3 and 4, the colored layer 50 is disposed below the decorative film (the side opposite the adhesive layer 20), but such a colored layer may be disposed between the decorative film 30 and the second adhesive layer 60 in the laminate 4 shown in Fig. 4, for example. The colored layer may be disposed below the decorative film (the side opposite the adhesive layer 20) as a colored adhesive layer.

[0033] In addition, between the transparent member and the adhesive layer, and between the adhesive layer and the decorative film, an additional layer such as an undercoat layer or an easy-adhesion layer may be provided, and any layer such as a layer containing a colorant within a range of transparency may be provided on at least a part of the surface (the entire surface or a part of the surface). A protective layer such as a hard coat layer may be provided on the opposite side (outside) of the transparent member from the adhesive layer side.

[0034] The adhesive layer may be an adhesive layer containing a substrate in which a non-removable substrate is embedded. Examples of substrates that can be used include plastic film, paper, and nonwoven fabric. Although the (first) adhesive layer 20 and the second adhesive layer 60 have a single-layer structure in Figs. 1 to 4, the structure of the adhesive layer is not limited thereto. For example, the adhesive layer may be configured to include two or more sub-adhesive layers made of the same or different adhesives. From the viewpoints of productivity and transparency, an adhesive layer having a single-layer structure is preferred.

[0035] <Characteristics of laminate> The laminate disclosed herein suitably has a visible light transmittance of less than 30% in the lamination direction of the transparent member, the adhesive layer, and the decorative film. The laminate thus constructed can have good concealment while exhibiting the design of the decorative film. For example, when the transparent member of the laminate is used as a housing for a structure such as a portable electronic device, the inside of the structure is concealed, while the design of the decorative film is visible on the outer surface through the transparent member and the adhesive layer.

[0036] From the viewpoint of concealment and light-shielding properties, the visible light transmittance of the laminate may be less than 20%, preferably less than 10%, and may be 7.0% or less, for example, 3.0% or less, or even 1.0% or less (substantially 0 to 1.0%). The visible light transmittance of the laminate can be adjusted by setting the transparency of the decorative film, the arrangement and thickness of one or more colored layers, the selection and concentration of the colorant in the colored layer, etc. The visible light transmittance of the laminate is obtained by measuring the transmittance in the visible light region (380 to 780 nm) with a spectrophotometer. It is measured in the same manner in the examples described later.

[0037] <Transparent material> The transparent member disclosed herein may be any member having transparency, and is not particularly limited in its scope. The material constituting the transparent member may be, for example, glass such as alkali glass or non-alkali glass; resin materials such as acrylic resin, ABS resin, polycarbonate resin, transparent polyimide, polyester resin such as polyethylene terephthalate (PET), polystyrene resin, etc. The transparent member material may be used alone or in combination by laminating two or more types.

[0038] In some embodiments, the total light transmittance of the transparent member is, for example, about 50% or more, and is suitably about 70% or more. From the viewpoint of visibility of the decorative film through the transparent member, in some preferred embodiments, the total light transmittance of the transparent member is about 85% or more, and more preferably about 90% or more. Theoretically, the upper limit of the total light transmittance is a value obtained by subtracting the light loss (Fresnel loss) caused by reflection at the air interface from 100%, and in practical use, it may be about 95% or less, or about 94% or less (for example, 93% or less).

[0039] (Haze value) In some embodiments, the haze value of the transparent member is, for example, about 10% or less, and is suitably about 3% or less. From the viewpoint of visibility through the transparent member, in some preferred embodiments, the haze value of the transparent member is about 1% or less, more preferably about 0.8% or less, and even more preferably 0.5% or less. The lower limit of the haze value is theoretically 0%, and in practice, it may be more than about 0.0%. The "haze value" refers to the ratio of diffuse transmitted light to the total transmitted light when visible light is irradiated onto the measurement target. It is also called the cloudiness value. The haze value can be expressed by the following formula. Th[%]=Td / Tt×100 In the above formula, Th is the haze value [%], Td is the scattered light transmittance, and Tt is the total light transmittance.

[0040] The total light transmittance and haze value of the transparent member can be measured using a haze meter, such as the "HM-150N" manufactured by Murakami Color Research Laboratory or an equivalent product.

[0041] The transparent member having the above total light transmittance and haze value may be a colored transparent or colorless transparent member. In this specification, the term "transparent" is used in a sense that includes translucency.

[0042] The transparent member may be flat, but may have unevenness such as printing or engraving on the adhesive layer attachment surface, or the transparent member may have a three-dimensional shape as a whole. The adhesive layer disclosed herein may have excellent step conformability, so it can adhere well to the uneven transparent member surface. In addition, the transparent member having a three-dimensional shape may have a bent portion that is bent linearly or a curved portion that is curved curved in a curved line in a cross section in the thickness direction. The transparent member may have a shape in which the surface on the adhesive layer side is bent or curved in any one direction, or may have a shape in which the surface on the adhesive layer side is bent or curved in two directions that intersect (for example, perpendicular to) the one direction in addition to the one direction. In other words, the surface on the adhesive layer side of the transparent member may have a two-dimensional or three-dimensional structure.

[0043] In an embodiment including a transparent member having a two-dimensional or three-dimensional structure as described above, the adhesive layer and the decorative film laminated on the transparent member, and further, if necessary, additional layers such as a colored layer, may be disposed only on the flat portion of the transparent member, or may be disposed not only on the flat portion but also on the three-dimensional portion of the transparent member (specifically, on the bent portion or curved portion). By configuring in this way, the design of the decorative film surface can be viewed through the transparent member and the adhesive layer even in the three-dimensional portion of the transparent member, and the laminate can have a shielding property even in the three-dimensional portion of the transparent member.

[0044] The thickness of the transparent member is appropriately set according to the purpose and mode of use, and is not limited to a specific range. The thickness of the transparent member is, for example, 0.01 mm or more, and is appropriately 0.05 mm or more, and from the viewpoint of strength, etc., is preferably 0.1 mm or more, may be 0.5 mm or more, may be 1 mm or more, or may be 3 mm or more. The thickness of the transparent member is appropriately about 30 mm or less, and is preferably about 10 mm or less, may be about 7 mm or less, may be about 5 mm or less, may be about 2 mm or less, or may be less than 1 mm (for example, less than 0.3 mm).

[0045] <Adhesive layer> In the technology disclosed herein, the type of adhesive constituting the adhesive layer (including the first adhesive layer and the second adhesive layer; the same applies hereinafter unless otherwise specified) is not particularly limited. The adhesive layer may be an adhesive layer composed of one or more types of adhesive selected from various known adhesives such as, for example, acrylic adhesives, rubber adhesives (natural rubber-based, synthetic rubber-based, and mixtures thereof), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine-based adhesives. Here, the acrylic adhesive refers to an adhesive having an acrylic polymer as the base polymer (the main component of the polymer component, i.e., a component contained in an amount of more than 50% by weight). The same applies to rubber adhesives and other adhesives.

[0046] (Polymer (A)) In some embodiments, the pressure-sensitive adhesive layer contains a polymer (A). Examples of materials that can be used as the polymer (A) include polymers that exhibit rubber elasticity at room temperature, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine polymers, which are known in the field of pressure-sensitive adhesives. These can be used alone or in combination of two or more.

[0047] The weight ratio of the polymer (A) to the total weight of the adhesive layer is suitably 40% by weight or more from the viewpoint of adhesive properties such as impact resistance, preferably 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more, and may be about 80% by weight or more, about 90% by weight or more, or about 97% by weight or more (for example, about 99% by weight or more). Adhesives with a high content of polymer (A) tend to have excellent transparency. In addition, the weight ratio of the polymer (A) to the total weight of the adhesive layer is typically less than 100% by weight, and from the viewpoint of easily adjusting the balance of properties, it is advantageous to be 95% by weight or less, preferably 92% by weight or less, and may be 90% by weight or less, or may be 87% by weight or less.

[0048] An acrylic polymer is a suitable example of the polymer (A). The adhesive layer in the technology disclosed herein may be an acrylic adhesive layer containing an acrylic polymer as a base polymer (the main component of the polymer components, i.e., a component that accounts for more than 50% by weight). Acrylic adhesives are preferable from the viewpoints of transparency and weather resistance, and are easy to realize viscoelastic properties with excellent impact resistance without relying heavily on additives such as softeners. The acrylic polymer as the polymer (A) (hereinafter, may be referred to as "acrylic polymer (A)") is preferably an acrylic polymer composed of a monomer component containing 40% by weight or more of (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms at the ester terminal. Hereinafter, a (meth)acrylic acid alkyl ester having an alkyl group having X to Y carbon atoms at the ester terminal is referred to as "(meth)acrylic acid C alkyl ester." X-Y It is sometimes referred to as "alkyl ester".

[0049] In some embodiments, (meth)acrylic acid C is the most abundant monomer component of the acrylic polymer (A). 1-20The proportion of the alkyl ester is preferably more than 40% by weight, since this makes it easier to balance the properties, and may be, for example, 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or more. 1-20 The proportion of the alkyl ester may be 100% by weight, but is preferably 98% by weight or less in order to easily balance the properties, and may be, for example, 95% by weight or less, or may be 90% by weight or less. In some embodiments, the proportion of C in the total monomer components of the acrylic polymer (A) is 1-20 From the viewpoint of improving the cohesiveness of the pressure-sensitive adhesive layer, the proportion of the (meth)acrylic acid alkyl ester may be, for example, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, or 60% by weight or less.

[0050] (Meth)acrylic acid C 1-20 Non-limiting examples of alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl ... and isopropyl (meth)acrylate. Examples of such acrylates include isooctyl, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0051] Among these, at least (meth)acrylic acid C4-20 It is preferable to use an alkyl ester, and at least (meth)acrylic acid C 4-18 It is more preferable to use alkyl esters. Particularly preferred (meth)acrylic acid C 4-18 Examples of alkyl esters include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). 4-20 Other specific examples of alkyl esters include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA), etc. 4-20 The alkyl esters can be used alone or in combination of two or more.

[0052] The monomer component preferably contains, for example, either one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). In some embodiments, the monomer component preferably contains at least BA. Here, examples of the monomer component containing at least BA include a monomer component having a composition that contains BA but not 2EHA, and a monomer component having a composition that contains BA and 2EHA and in which the content of 2EHA is less than the content of BA (for example, the content of 2EHA is less than 0.5 times or less than 0.3 times the content of BA).

[0053] In some embodiments, the monomer component constituting the acrylic polymer (A) is (meth)acrylic acid C 4-18 The monomer component may contain 40% by weight or more of alkyl ester. 4-18 The proportion of alkyl ester may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more. In addition, from the viewpoint of enhancing the cohesiveness of the adhesive layer, (meth)acrylic acid C in the monomer components 4-18The proportion of alkyl ester is suitably 99.5% by weight or less, may be 95% by weight or less, may be 85% by weight or less, or may be 75% by weight or less.

[0054] The monomer components constituting the acrylic polymer (A) may contain, in addition to the (meth)acrylic acid alkyl ester, other monomers (copolymerizable monomers) that are copolymerizable with the (meth)acrylic acid alkyl ester, if necessary. As the copolymerizable monomer, a monomer having a polar group (e.g., a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, etc.) or a monomer having a relatively high homopolymer glass transition temperature (e.g., 10°C or higher) can be suitably used. The monomer having a polar group can be useful for introducing a crosslinking point into the acrylic polymer (A) or for increasing the cohesive strength of the adhesive. The copolymerizable monomers can be used alone or in combination of two or more.

[0055] Non-limiting examples of copolymerizable monomers include the following: Carboxy group-containing monomers: for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and the like. Acid anhydride group-containing monomers: for example, maleic anhydride, itaconic anhydride. Hydroxyl group-containing monomers: for example, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Monomers containing a sulfonic acid group or a phosphoric acid group: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethyl acryloyl phosphate, etc. Epoxy group-containing monomers: for example, epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl ether (meth)acrylate, allyl glycidyl ether, and glycidyl ether (meth)acrylate. Cyano group-containing monomers: for example, acrylonitrile, methacrylonitrile, etc. Isocyanate group-containing monomers: for example, 2-isocyanatoethyl (meth)acrylate. Amide group-containing monomers: for example, (meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide; N-alkyl(meth)acrylamides such as N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and Nn-butyl(meth)acrylamide; N-vinyl carboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, for example, N-(2-hydroxyethyl)(meth)acrylamide; N-hydroxyalkyl (meth)acrylamides such as N-(2-hydroxypropyl) (meth)acrylamide, N-(1-hydroxypropyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(2-hydroxybutyl) (meth)acrylamide, N-(3-hydroxybutyl) (meth)acrylamide, and N-(4-hydroxybutyl) (meth)acrylamide; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth)acrylamide such as N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide; and others, N,N-dimethylaminopropyl (meth)acrylamide, N-(meth)acryloylmorpholine, and the like. Amino group-containing monomers: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate. Monomers having an epoxy group: for example, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether. Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc. (for example, lactams such as N-vinyl-2-caprolactam). Monomers having a succinimide skeleton: for example, N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyhexamethylene succinimide, and the like. Maleimides: for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, and the like. Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, and the like. Aminoalkyl (meth)acrylates: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate. Alkoxy group-containing monomers: for example, alkoxyalkyl (meth)acrylates (alkoxyalkyl (meth)acrylates) such as 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate; alkoxyalkylene (meth)acrylates (for example, alkoxypolyalkylene glycol (meth)acrylates) such as methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate. Alkoxysilyl group-containing monomers: for example, alkoxysilyl group-containing (meth)acrylates such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; and the like. Vinyl esters: for example, vinyl acetate, vinyl propionate, etc. Vinyl ethers: for example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether. Aromatic vinyl compounds: for example, styrene, α-methylstyrene, vinyltoluene, etc. Olefins: For example, ethylene, butadiene, isoprene, isobutylene, etc. (Meth)acrylic acid esters having an alicyclic hydrocarbon group: for example, (meth)acrylates containing an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and adamantyl (meth)acrylate. (Meth)acrylic acid esters having an aromatic hydrocarbon group: for example, (meth)acrylates containing an aromatic hydrocarbon group such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate. Other examples include heterocyclic ring-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen atom-containing (meth)acrylates such as vinyl chloride and fluorine atom-containing (meth)acrylates, silicon atom-containing (meth)acrylates such as silicone (meth)acrylate, and (meth)acrylic acid esters obtained from alcohols derived from terpene compounds.

[0056] When such a copolymerizable monomer is used, the amount of the copolymerizable monomer is not particularly limited, but is suitably 0.01% by weight or more of the total monomer components. From the viewpoint of better exerting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer may be 0.1% by weight or more of the total monomer components, or may be 0.5% by weight or more. Also, from the viewpoint of easily balancing the adhesive properties, the amount of the copolymerizable monomer is suitably 50% by weight or less of the total monomer components, and preferably 40% by weight or less.

[0057] In some embodiments, the monomer component constituting the acrylic polymer (A) may contain a monomer having a nitrogen atom. The use of a monomer having a nitrogen atom can increase the cohesive strength of the adhesive and favorably improve the peel strength after photocuring. A suitable example of the monomer having a nitrogen atom is a monomer having a nitrogen atom-containing ring. As the monomer having a nitrogen atom-containing ring, those exemplified above can be used, and for example, a monomer represented by the general formula (1): [ka] In the general formula (1), N-vinyl cyclic amide represented by the formula: 1 is a divalent organic group, specifically -(CH2) n -. n is an integer of 2 to 7 (preferably 2, 3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably used. Another suitable example of the monomer having a nitrogen atom is (meth)acrylamide.

[0058] The amount of the monomer having a nitrogen atom (preferably a monomer having a nitrogen atom-containing ring) used is not particularly limited, and may be, for example, 1% by weight or more, 3% by weight or more, or even 5% by weight or more or 7% by weight or more of the total monomer components. In some embodiments, the amount of the monomer having a nitrogen atom used may be 10% by weight or more, 15% by weight or more, or 20% by weight or more of the total monomer components. In addition, the amount of the monomer having a nitrogen atom used is suitably, for example, 40% by weight or less of the total monomer components, and may be 35% by weight or less, 30% by weight or less, or 25% by weight or less. In some other embodiments, the amount of the monomer having a nitrogen atom used may be, for example, 20% by weight or less, or 15% by weight or less of the total monomer components.

[0059] In some embodiments, the monomer components constituting the acrylic polymer (A) may contain a hydroxyl group-containing monomer. By using a hydroxyl group-containing monomer, the cohesive strength of the adhesive and the degree of crosslinking (for example, crosslinking by an isocyanate crosslinking agent) can be suitably adjusted. When using a hydroxyl group-containing monomer, the amount used is not particularly limited, and may be, for example, 0.01% by weight or more of the total monomer components, 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 5% by weight or more, or 10% by weight or more. In addition, from the viewpoint of suppressing the water absorption of the adhesive layer, in some embodiments, the amount of the hydroxyl group-containing monomer used is suitably, for example, 40% by weight or less of the total monomer components, and may be 30% by weight or less, 25% by weight or less, or 20% by weight or less. In some other embodiments, the amount of the hydroxyl group-containing monomer used may be, for example, 15% by weight or less, 10% by weight or less, or 5% by weight or less of the total monomer components.

[0060] In some embodiments, the ratio of the carboxyl group-containing monomer in the monomer components of the acrylic polymer (A) may be, for example, 2% by weight or less, 1% by weight or less, or 0.5% by weight or less (for example, less than 0.1% by weight). The acrylic polymer (A) may not substantially use a carboxyl group-containing monomer as a monomer component. Here, substantially not using a carboxyl group-containing monomer means that at least intentionally not using a carboxyl group-containing monomer. The pressure-sensitive adhesive layer containing the acrylic polymer (A) in which the amount of the carboxyl group-containing monomer used is limited as described above is preferable from the viewpoint of preventing metal corrosion. Such a pressure-sensitive adhesive layer may also be preferably used in an embodiment in which it comes into contact with an adherend having a metal material, for example.

[0061] In some embodiments, the monomer component constituting the acrylic polymer (A) may contain an alicyclic hydrocarbon group-containing (meth)acrylate. This can increase the cohesive force of the adhesive and improve the peel strength after photocuring. As the alicyclic hydrocarbon group-containing (meth)acrylate, the above-mentioned examples can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably used. When using an alicyclic hydrocarbon group-containing (meth)acrylate, the amount used is not particularly limited, and can be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more of the entire monomer component. In some embodiments, the amount used of the alicyclic hydrocarbon group-containing (meth)acrylate may be 10% by weight or more, or 15% by weight or more of the entire monomer component. The upper limit of the amount used of the alicyclic hydrocarbon group-containing (meth)acrylate is suitably about 40% by weight or less, and may be, for example, 30% by weight or less, or 25% by weight or less (for example, 15% by weight or less, or even 10% by weight or less).

[0062] The polymerization method for forming (synthesizing) the polymer (A) from the monomer components is not particularly limited, and various conventionally known polymerization methods can be appropriately adopted. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically carried out in the presence of a thermal polymerization initiator); photopolymerization carried out by irradiating light such as ultraviolet light (typically carried out in the presence of a photopolymerization initiator); radiation polymerization carried out by irradiating radiation such as β rays and γ rays; and other polymerization methods can be appropriately adopted. Two or more polymerization methods may be combined (for example, stepwise) to be carried out.

[0063] As the solvent for solution polymerization (polymerization solvent), for example, any one solvent selected from aromatic compounds such as toluene (typically aromatic hydrocarbons); esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; and ketones such as methyl ethyl ketone; or a mixed solvent of two or more of them can be used.

[0064] In the polymerization, a known or commonly used thermal polymerization initiator or photopolymerization initiator may be used depending on the polymerization method, polymerization mode, etc. Such polymerization initiators may be used alone or in appropriate combination of two or more.

[0065] The thermal polymerization initiator is not particularly limited, and examples thereof include azo polymerization initiators, peroxide initiators, redox initiators formed by combining peroxides with reducing agents, and substituted ethane initiators. More specifically, examples thereof include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[N-(2-carboxyethyl)-2- Examples of initiators include, but are not limited to, azo initiators such as methylpropionamidine hydrate; persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide, and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; redox initiators such as a combination of a persulfate and sodium hydrogen sulfite, and a combination of a peroxide and sodium ascorbate. Thermal polymerization can be preferably carried out at a temperature of, for example, about 20 to 100°C (typically 40 to 80°C), but is not limited thereto.

[0066] The photopolymerization initiator is not particularly limited, but examples of the photopolymerization initiator that can be used include ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators.

[0067] The amount of the polymerization initiator used is not particularly limited and may be a normal amount depending on the polymerization method, polymerization mode, etc. For example, about 0.001 to 5 parts by weight (typically about 0.01 to 2 parts by weight, for example about 0.01 to 1 part by weight) of the polymerization initiator can be used relative to 100 parts by weight of the monomer to be polymerized.

[0068] In the above polymerization, various conventionally known chain transfer agents (which may also be understood as molecular weight regulators or polymerization degree regulators) may be used as necessary. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α-thioglycerol may be used. Alternatively, a chain transfer agent that does not contain a sulfur atom (non-sulfur chain transfer agent) may be used. Specific examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; styrenes such as α-methylstyrene and α-methylstyrene dimer; compounds having a benzylidene group such as dibenzylideneacetone, cinnamyl alcohol, and cinnamylaldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; olefins such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; and the like. The chain transfer agent can be used alone or in combination of two or more. The technology disclosed herein can also be preferably implemented in an embodiment in which no chain transfer agent is used.

[0069] When a chain transfer agent is used, the amount of the chain transfer agent used can be, for example, about 0.005 to 1 part by weight relative to 100 parts by weight of the monomer component. In some embodiments, from the viewpoint of impact resistance, the amount of the chain transfer agent used relative to 100 parts by weight of the monomer component can be, for example, 0.01 parts by weight or more, or 0.03 parts by weight or more, or 0.05 parts by weight or more, or 0.07 parts by weight or more. In some embodiments, from the viewpoint of deformation resistance, the amount of the chain transfer agent used relative to 100 parts by weight of the monomer component can be, for example, 0.5 parts by weight or less, or 0.2 parts by weight or less, or 0.1 parts by weight or less (for example, 0.09 parts by weight or less).

[0070] In the technology disclosed herein, the glass transition temperature (Tg) of the polymer (A) is not particularly limited, but is suitably less than 0°C, preferably less than -10°C, and preferably less than -20°C. The impact resistance tends to improve as the Tg of the polymer (A) decreases. In some embodiments, the Tg of the polymer (A) may be less than -25°C or less than -30°C. The Tg of the polymer (A) is typically -80°C or higher, for example, -70°C or higher, -60°C or higher, or -55°C or higher. From the viewpoint of increasing the elastic modulus, in some embodiments, the Tg of the polymer (A) is preferably -50°C or higher, more preferably -45°C or higher, and may be -40°C or higher, -38°C or higher, or -35°C or higher.

[0071] In this specification, the Tg of a polymer refers to the Tg calculated by the Fox formula based on the composition of the monomer components used in the preparation of the polymer. The Fox formula is a relational expression between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below. 1 / Tg=Σ(Wi / Tgi)

[0072] In the above Fox formula, Tg represents the glass transition temperature (unit: K) of the copolymer, Wi represents the weight fraction (copolymerization ratio by weight) of monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of a homopolymer of monomer i. When the target polymer for which Tg is specified is a homopolymer, the Tg of the homopolymer and the Tg of the target polymer are the same.

[0073] The glass transition temperature of the homopolymer used to calculate Tg is a value described in a publicly known document. For example, for the monomers listed below, the following values ​​are used as the glass transition temperatures of the homopolymers of the monomers. n-Butyl acrylate -55℃ 2-Ethylhexyl acrylate -70℃ Isostearyl acrylate -18℃ Cyclohexyl acrylate 15℃ N-vinyl-2-pyrrolidone 54℃ 2-Hydroxyethyl acrylate -15℃ 4-Hydroxybutyl acrylate -40℃

[0074] For the glass transition temperatures of homopolymers of monomers other than those listed above, the values ​​given in "Polymer Handbook" (3rd Edition, John Wiley & Sons, Inc., 1989) shall be used. When multiple values ​​are given in this document, the highest value shall be used.

[0075] The weight average molecular weight (Mw) of the polymer (A) is not particularly limited. From the viewpoint of achieving a good balance between deformation resistance and impact resistance, in some embodiments, the Mw of the polymer (A) is, for example, about 10 × 10 4 It is appropriate that the value is 20 x 10 or more. 4 More preferably, it is greater than 30×10 4 Ultra-fine, 40 x 10 4 Ultra-fine, even 50 x 10 4 The upper limit of Mw of the polymer (A) is about 500×10 4 From the viewpoint of adhesion to an adherend and peel strength, in some embodiments, the Mw of the polymer (A) can be, for example, 300×10 4 may be less than or equal to 150 x 10 4 Less than 100 x 10 4 Less than 90×10 is fine. 4 Less than 75×10 is fine. 4 The following is also fine. The above examples of Mw may be applied to the Mw of polymer (A) in the pressure-sensitive adhesive layer disclosed herein, or may be applied to the Mw of polymer (A) in the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer.

[0076] The Mw refers to a value calculated based on standard polystyrene obtained by gel permeation chromatography (GPC). As the GPC device, for example, a model named "HLC-8220GPC" (manufactured by Tosoh Corporation) or an equivalent device can be used. As the measurement conditions for GPC, for example, the following method is adopted. The Mw in the examples described later is measured by the following method. (GPC measurement conditions) Equipment: Tosoh Corporation, HLC-8220GPC column: Sample column: Tosoh Corporation, TSKguardcolumn Super HZ-H (1 column) + TSKgel Super HZM-H (2 columns) Reference column: Tosoh Corporation, TSKgel Super H-RC (1 column) Flow rate: 0.6mL / min Injection volume: 10μL Column temperature: 40℃ Eluent:THF Injected sample concentration: 0.2% by weight Detector: Differential refractometer The weight average molecular weight is calculated based on polystyrene conversion.

[0077] (Photoreactive monomer (B)) In some preferred embodiments, the pressure-sensitive adhesive layer may contain a photoreactive monomer (B) in addition to the polymer (A) (for example, acrylic polymer (A)) as described above. As the photoreactive monomer (B), a compound having 2 or more ethylenically unsaturated groups in the molecule (hereinafter also referred to as "functional group number"). The upper limit of the functional group number of the compound used as the photoreactive monomer (B) is not particularly limited. The functional group number may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. In some embodiments, a compound having an ethylenically unsaturated group with a functional group number of, for example, 2 to 10 may be used, a compound with a functional group number of 2 to 8 is preferably used, and a compound with a functional group number of 2 to 6 is more preferably used. The photoreactive monomer (B) may be used alone or in combination of two or more.

[0078] The photoreactive monomer (B) contained in the pressure-sensitive adhesive layer can form a crosslinked structure by reacting the ethylenically unsaturated group with light (e.g., ultraviolet) irradiation or the like after application to an adherend. The pressure-sensitive adhesive layer containing the photoreactive monomer (B) can be cured by ultraviolet irradiation or the like after application to an adherend to increase the deformation resistance of the pressure-sensitive adhesive layer. This can suitably achieve both good conformability to the surface shape of the adherend when applied to the adherend and high deformation resistance after application.

[0079] Examples of the ethylenically unsaturated group include, but are not limited to, an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group. The two or more ethylenically unsaturated groups that the photoreactive monomer (B) has in its molecule may be the same group, or may be two or more different groups. From the viewpoint of photoreactivity, preferred ethylenically unsaturated groups include an acryloyl group and a methacryloyl group. Among them, an acryloyl group is preferred.

[0080] The functional group equivalent of the compound used as the photoreactive monomer (B) is not particularly limited. The functional group equivalent may be, for example, about 50 to 10,000 g / mol, about 50 to 8,000 g / mol, about 50 to 5,000 g / mol, about 50 to 3,000 g / mol, or about 50 to 2,000 g / mol. In some embodiments, from the viewpoint of photocurability, a compound having a functional group equivalent of about 60 to 800 g / mol (more preferably about 80 to 600 g / mol) may be preferably used as the photoreactive monomer (B).

[0081] The functional group equivalent of the photoreactive monomer (B) is calculated by dividing the molecular weight [g / mol] of the photoreactive monomer (B) by the number of ethylenically unsaturated functional groups contained in the photoreactive monomer (B). The molecular weight of the photoreactive monomer (B) can be obtained, for example, by the GPC method as a weight average molecular weight converted into standard polystyrene. In addition, the molecular weight [g / mol] of the photoreactive monomer (B) may be the manufacturer's nominal value or a molecular weight calculated from the molecular structure.

[0082] The molecular weight of the photoreactive monomer (B) is not particularly limited and may be selected so that the desired effect is suitably exhibited. For example, a photoreactive monomer (B) having a molecular weight of about 20,000 or less can be used. From the viewpoint of preparation ease and coatability of the pressure-sensitive adhesive composition, in some embodiments, the molecular weight of the photoreactive monomer (B) may be, for example, 16,000 or less, 10,000 or less, 4,000 or less, 1,500 or less, or 1,000 or less. The molecular weight of the photoreactive monomer (B) is, for example, 100 or more, typically 120 or more. From the viewpoint of processability and handleability, in some embodiments, the molecular weight of the photoreactive monomer (B) may be, for example, 150 or more, 200 or more, 280 or more, 350 or more, 420 or more, 480 or more, or 550 or more.

[0083] In the laminate disclosed herein, the amount of the photoreactive monomer (B) contained in the adhesive layer is not particularly limited and can be appropriately set according to the target performance (for example, the elastic modulus of the adhesive layer after photocuring). In some embodiments in which the adhesive layer contains a polymer (A) and a photoreactive monomer (B), the amount of the photoreactive monomer (B) relative to 100 parts by weight of the polymer (A) contained in the adhesive layer may be, for example, 1 part by weight or more, and is suitably 3 parts by weight or more. From the viewpoint of easily increasing the elastic modulus of the adhesive layer after photocuring, the amount of the photoreactive monomer (B) relative to 100 parts by weight of the polymer (A) may be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more. In addition, from the viewpoint of the cohesiveness and handleability (e.g., processability) of the adhesive layer before photocuring, the amount of photoreactive monomer (B) per 100 parts by weight of polymer (A) is suitably 80 parts by weight or less, preferably 60 parts by weight or less, or may be 50 parts by weight or less, 40 parts by weight or less, or 35 parts by weight or less.

[0084] In some embodiments, the pressure-sensitive adhesive layer preferably contains at least a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule as the photoreactive monomer (B). The pressure-sensitive adhesive layer containing the compound B1 of such a structure can effectively increase the deformation resistance of the pressure-sensitive adhesive layer by light irradiation. The ring in the ring structure may be an aliphatic ring or an aromatic ring. The ring may be a carbon ring or a heterocycle. The number of rings contained in one molecule of compound B1 may be 1 or 2 or more. The upper limit of the number of rings contained in compound B1 is not particularly limited, and may be, for example, 100 or less, 70 or less, 50 or less, 30 or less, 15 or less, 8 or less, 6 or less, 5 or less, or 4 or less. When compound B1 contains two or more rings, the rings may or may not form a condensed ring (typically a bicyclic or tricyclic condensed ring) by one or two or more rings. The ring is preferably included in the main chain of compound B1. That is, it is preferable that one ethylenically unsaturated group of compound B1 and at least one other ethylenically unsaturated group are linked via the ring structure. Compound B1 can be used alone or in combination of two or more.

[0085] Compound B1 may preferably be a compound having a ring structure and two or more ethylenically unsaturated groups in the molecule and a functional group equivalent of 100 g / mol or more. When compound B1 that satisfies the above functional group equivalent is used in the adhesive layer, a bond having high deformation resistance and high impact resistance can be suitably formed. The reason for obtaining such an effect is not particularly limited, but it is considered that compound B1 can effectively increase the elastic modulus of the adhesive layer after light irradiation due to the rigidity of the ring structure, thereby imparting deformation resistance, while the functional group equivalent of compound B1 is a predetermined value or more, thereby maintaining the distance between crosslinking points and forming a crosslinked structure having high impact resistance. In some embodiments, the functional group equivalent of compound B1 may be, for example, 120 g / mol or more, 150 g / mol or more, 180 g / mol or more, 230 g / mol or more, 280 g / mol or more, 320 g / mol or more, or 350 g / mol or more. The impact resistance tends to improve by increasing the functional group equivalent of compound B1. In addition, the functional group equivalent of compound B1 may be, for example, 10000g / mol or less, 8000g / mol or less, 5000g / mol or less, 3000g / mol or less, or 2000g / mol or less. In some embodiments, from the viewpoint of photocurability, etc., the functional group equivalent of compound B1 is preferably 800g / mol or less, more preferably 600g / mol or less. In some embodiments, the functional group equivalent of compound B1 may be 500g / mol or less, 400g / mol or less, or 300g / mol or less.

[0086] In some embodiments, the number of functional groups of compound B1 may be, for example, 2 to 50, 2 to 40, 2 to 30, or 2 to 10, and is preferably, for example, 2 to 6, 2 to 4, or 2 to 3. In some embodiments, compound B1 having 2 functional groups may be preferably used.

[0087] Compound B1 may have a functional group other than the ethylenically unsaturated group. Examples of the functional group other than the ethylenically unsaturated group include a hydroxyl group, a carboxyl group, and an amino group. Suitable examples of the functional group other than the ethylenically unsaturated group include a hydroxyl group and an amino group.

[0088] Examples of the compound B1 include bisphenol A type epoxy (meth)acrylates such as bisphenol A glycidyl ether (meth)acrylic acid adduct, bisphenol A glycidyl amine (meth)acrylic acid adduct, and bisphenol A glycidyl ester (meth)acrylic acid adduct; alkylene oxide modified bisphenol A (meth)acrylates such as ethylene oxide (EO) modified bisphenol A di(meth)acrylate and propylene oxide (PO) modified bisphenol A di(meth)acrylate; bisphenol F type epoxy (meth)acrylates such as bisphenol F glycidyl ether (meth)acrylic acid adduct, bisphenol F glycidyl amine (meth)acrylic acid adduct, and bisphenol F glycidyl ester (meth)acrylic acid adduct; alkylene oxide modified bisphenol F (meth)acrylates such as EO modified bisphenol F di(meth)acrylate and PO modified bisphenol F di(meth)acrylate; bisphenol E glycidyl ether (meth)acrylic acid adduct, bisphenol E Bisphenol E type epoxy (meth)acrylates such as glycidylamine (meth)acrylic acid adduct and bisphenol E glycidyl ester (meth)acrylic acid adduct; alkylene oxide modified bisphenol E (meth)acrylates such as EO modified bisphenol E di(meth)acrylate and PO modified bisphenol E di(meth)acrylate; 9,9-bis(4-hydroxyphenyl)fluoren-di(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluoren-di(meth)acrylate (meth)acrylates containing a fluorene skeleton, such as acrylate; aliphatic rings (alicyclic condensed rings), such as tricyclodecane dimethanol di(meth)acrylate, hydrogenated bisphenol A type epoxy (meth)acrylate, hydrogenated bisphenol F type epoxy (meth)acrylate, hydrogenated bisphenol E type epoxy (meth)acrylate, hydrogenated phthalic acid type epoxy (meth)acrylate, hydrogenated terpene phenol (meth)acrylate, and 1,4-cyclohexane dimethanol diglycidyl ether (meth)acrylate.(Meth)acrylates having the above structure; (meth)acrylic acid adducts of novolac-type epoxy resins; (meth)acrylic acid adducts of thioether-type epoxy resins; (meth)acrylic acid adducts of naphthalene-type epoxy resins; (meth)acrylic acid adducts of dicyclopentadiene-type epoxy resins; (meth)acrylic acid adducts of alkyldiphenol-type epoxy resins; (meth)acrylic acid adducts of biphenyl-type epoxy resins; (meth)acrylic acid adducts of terpene phenol resins; isocyanurate-type (meth)acrylates such as tris(2-hydroxyethyl)isocyanurate di(meth)acrylate and tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; divinylbenzene; hydroquinone di(meth)acrylate; resorcinol di(meth)acrylate; modified products of any of the above materials (e.g., amine modified products, acid modified products, halogen modified products); and the like, but are not limited thereto. In some embodiments, a compound B1 having an aromatic carbon ring may be preferably employed. Suitable examples of the compound B1 include compounds containing a bisphenol A structure, such as bisphenol A type epoxy (meth)acrylate, alkylene oxide modified bisphenol A (meth)acrylate, and modified products thereof (eg, amine modified products).

[0089] Examples of commercially available products that can be used as compound B1 include, but are not limited to, products manufactured by Shin-Nakamura Chemical Co., Ltd. under the trade names "A-DCP" and "A-BPE-4", products manufactured by Osaka Organic Chemical Industry Co., Ltd. under the trade names "Viscoat #540" and "Viscoat #700HV", products manufactured by Nippon Kayaku Co., Ltd. under the trade names "Epoxy Ester 3000A" and "Epoxy Ester 80MFA" manufactured by Kyoeisha Chemical Co., Ltd., and products manufactured by Daicel Allnex under the trade names "EBECRYL 3700", "EBECRYL 3703", and "EBECRYL 3603".

[0090] The amount of compound B1 relative to 100 parts by weight of polymer (A) contained in the adhesive layer is not particularly limited, and can be, for example, 0.5 parts by weight or more. From the viewpoint of easily obtaining an adhesive layer that balances deformation resistance and impact resistance, in some embodiments, the amount of compound B1 relative to 100 parts by weight of polymer (A) may be, for example, 1 part by weight or more, 3 parts by weight or more, 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, or 15 parts by weight or more. In addition, from the viewpoint of the cohesiveness and handleability of the adhesive layer before photocuring, the amount of compound B1 relative to 100 parts by weight of polymer (A) is suitably 80 parts by weight or less, preferably 60 parts by weight or less, may be 50 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 25 parts by weight or less, or 15 parts by weight or less.

[0091] In some embodiments, the pressure-sensitive adhesive layer may contain, as the photoreactive monomer (B), a compound B2 having two or more functional groups and no ring structure in the molecule. Compound B2 is preferably used in combination with compound B1. This can adjust the crosslinked structure of the pressure-sensitive adhesive layer to form a bond that more suitably balances deformation resistance and impact resistance. Compound B2 can be used alone or in combination of two or more.

[0092] The number of functional groups of compound B2 may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. The number of functional groups of compound B2 used in some embodiments may be, for example, 2 to 10, preferably 3 to 10, 3 to 8, or 4 to 6. For example, in an embodiment in which a compound having 2 functional groups is used as compound B1, it may be advantageous to use compound B2 having 3 or more functional groups (preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more).

[0093] The functional group equivalent of the compound B2 is not particularly limited, and may be, for example, 5000 g / mol or less, 2000 g / mol or less, or 1000 g / mol or less. In some embodiments, the functional group equivalent of the compound B2 may be, for example, 600 g / mol or less, and from the viewpoint of improving the photocurability and hardness of the cured product, may be 400 g / mol or less, 300 g / mol or less, 200 g / mol or less, 150 g / mol or less, or 100 g / mol or less. The functional group equivalent of the compound B2 is typically 50 g / mol or more, preferably 60 g / mol or more, 70 g / mol or more, 80 g / mol or more, or 90 g / mol or more.

[0094] Examples of compounds that can be used as compound B2 include, but are not limited to, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, trimethylolethane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, EO modified products or PO modified products of any of the above-mentioned materials, and the like.

[0095] In the embodiment using the compound B2, the amount of the compound B2 relative to 100 parts by weight of the polymer (A) contained in the adhesive layer is not particularly limited, and can be, for example, 0.1 parts by weight or more. From the viewpoint of easily obtaining an adhesive layer that balances deformation resistance and impact resistance, in some embodiments, the amount of the compound B2 relative to 100 parts by weight of the polymer (A) may be, for example, 1 part by weight or more, 2 parts by weight or more, 4 parts by weight or more, 6 parts by weight or more, 10 parts by weight or more, or 12 parts by weight or more. In addition, from the viewpoint of suppressing a decrease in adhesion to the adherend due to excessive crosslinking, in some embodiments, the amount of the compound B2 relative to 100 parts by weight of the polymer (A) is, for example, appropriate to be 25 parts by weight or less, preferably 17 parts by weight or less, may be 15 parts by weight or less, may be 13 parts by weight or less, or may be 9 parts by weight or less.

[0096] In an embodiment in which compound B1 and compound B2 are used in combination, a compound having a functional group number of 3 or more and a functional group equivalent smaller than that of compound B1 used in combination therewith may be preferably used as compound B2. In some embodiments, the ratio (FE2 / FE1) of the functional group equivalent FE2 of compound B2 to the functional group equivalent FE1 of compound B1 may be, for example, 0.9 or less, 0.7 or less, 0.5 or less, or 0.4 or less. According to such an embodiment, the effect of improving the elastic modulus by the photoreactive monomer (B) may be efficiently exerted. The lower limit of the ratio (FE2 / FE1) is not particularly limited, and may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more.

[0097] In the embodiment in which the compound B1 and the compound B2 are used in combination, the weight ratio (W2 / W1) of the amount W2 of the compound B2 to the amount W1 of the compound B1 is not particularly limited. In some embodiments, the weight ratio (W2 / W1) may be, for example, 0.05 to 10, 0.1 to 5, 0.2 to 3, or 0.3 to 2. By setting the weight ratio (W2 / W1) to any of the above ranges, the effect of using the compound B1 and the compound B2 in combination tends to be favorably exhibited.

[0098] In some other embodiments using a photoreactive monomer (B) (typically compound B2), the amount of the photoreactive monomer (B) (typically compound B2) used can be about 3% by weight or less of the monomer components of the polymer (A), preferably about 2% by weight or less, more preferably about 1% by weight or less (e.g., about 0.5% by weight or less). The lower limit of the amount of the photoreactive monomer (B) (typically compound B2) used is not particularly limited, as long as it is greater than 0% by weight. It is appropriate to use the amount of the photoreactive monomer (B) (typically compound B2) of about 0.001% by weight or more (e.g., about 0.01% by weight or more) of the monomer components.

[0099] In some embodiments, the photoreactive monomer (B) may be contained in the pressure-sensitive adhesive layer in a free form. Such a pressure-sensitive adhesive layer may be suitably formed using a pressure-sensitive adhesive composition containing the photoreactive monomer (B) in a free form. Here, the term "free form" refers to the photoreactive monomer (B) not being chemically bonded to other components (e.g., polymer (A)) contained in the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition. A pressure-sensitive adhesive composition containing the photoreactive monomer (B) in a free form may be advantageous in terms of ease of preparation and suppression of gelation.

[0100] In some other embodiments, at least a part of the photoreactive monomer (B) may be included in the pressure-sensitive adhesive layer in a form chemically bonded to other components (e.g., polymer (A), a crosslinking agent described below, etc.) included in the pressure-sensitive adhesive layer or pressure-sensitive adhesive composition from the viewpoint of improving processability, etc. The chemical bond may be, for example, a bond formed by a reaction between a functional group F1 other than an ethylenically unsaturated group contained in the molecule of the photoreactive monomer (B) and a functional group F2 contained in the molecule of the other component and capable of reacting with the functional group F1. The other component may be a crosslinking agent, and the photoreactive monomer (B) may be bonded to the polymer (A) via the crosslinking agent.

[0101] (Acrylic Oligomer) The adhesive layer disclosed herein may contain an acrylic oligomer from the viewpoint of improving the cohesive force and improving the adhesion to the surface adjacent to the adhesive layer (for example, a transparent member or a decorative film). The adhesive layer containing the acrylic oligomer may be preferably formed using an adhesive composition containing the acrylic oligomer. As the acrylic oligomer, one having a higher Tg than the Tg of the above-mentioned polymer (A) may be preferably used.

[0102] The Tg of the acrylic oligomer is not particularly limited, and may be, for example, about 20°C or more and 300°C or less. The Tg may be, for example, about 30°C or more, about 40°C or more, about 60°C or more, about 80°C or more, or about 100°C or more. When the Tg of the acrylic oligomer is high, the effect of improving the cohesive force generally tends to be high. In addition, from the viewpoint of adhesion to the adherend and impact absorption, the Tg of the acrylic oligomer may be, for example, about 250°C or less, about 200°C or less, about 180°C or less, or about 150°C or less. The Tg of the acrylic oligomer is a value calculated based on the Fox formula, like the Tg of the polymer (A).

[0103] The Mw of the acrylic oligomer is not particularly limited, and may be, for example, about 1000 or more, suitably about 1500 or more, about 2000 or more, or about 3000 or more. The Mw of the acrylic oligomer may be, for example, less than about 30000, suitably less than about 10000, less than about 7000, or less than about 5000. When the Mw is within the above range, the effect of improving the cohesiveness of the pressure-sensitive adhesive layer and the adhesion to the adjacent surface is easily exhibited. The Mw of the acrylic oligomer can be measured by GPC and calculated as a value converted into standard polystyrene. Specifically, for example, it can be measured using 2 columns of TSKgel GMH-H (20) on a HPLC 8020 manufactured by Tosoh Corporation, with a flow rate of about 0.5 mL / min in tetrahydrofuran solvent.

[0104] As the monomer component constituting the acrylic oligomer, the above-mentioned various (meth)acrylic acids C 1-20 Examples of (meth)acrylate monomers include alkyl esters, the various alicyclic hydrocarbon group-containing (meth)acrylates described above, the various aromatic hydrocarbon group-containing (meth)acrylates described above, and (meth)acrylates obtained from alcohols derived from terpene compounds. These can be used alone or in combination of two or more.

[0105] From the viewpoint of improving adhesiveness, it is preferable that the acrylic oligomer contains, as a monomer unit, an acrylic monomer having a relatively bulky structure, such as an alkyl (meth)acrylate having a branched structure such as isobutyl (meth)acrylate or t-butyl (meth)acrylate, an alicyclic hydrocarbon group-containing (meth)acrylate, or an aromatic hydrocarbon group-containing (meth)acrylate, etc. In addition, when ultraviolet light is used in synthesizing the acrylic oligomer or in preparing the adhesive layer, a monomer having a saturated hydrocarbon group at the ester end is preferable in terms of being less likely to cause polymerization inhibition, and for example, an alkyl (meth)acrylate having a branched structure such as an alkyl group or a saturated alicyclic hydrocarbon group-containing (meth)acrylate can be suitably used.

[0106] The proportion of (meth)acrylate monomers in all monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more (e.g., 80% by weight or more, or even 90% by weight or more). In some preferred embodiments, the acrylic oligomer has a monomer composition substantially consisting of one or more (meth)acrylate monomers. The monomer components are an alicyclic hydrocarbon group-containing (meth)acrylate and (meth)acrylic acid C. 1-20 When the alkyl ester is included, the weight ratio thereof is not particularly limited. In some embodiments, the alicyclic hydrocarbon group-containing (meth)acrylate / (meth)acrylic acid C 1-20The weight ratio of the alkyl esters can be, for example, 10 / 90 or more, 20 / 80 or more, or 30 / 70 or more, and can be 90 / 10 or less, 80 / 20 or less, or 70 / 30 or less.

[0107] In addition to the above (meth)acrylate monomer, functional group-containing monomers can be used as monomer components constituting the acrylic oligomer, if necessary. Examples of functional group-containing monomers include monomers having nitrogen atom-containing heterocycles such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino group-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate; amide group-containing monomers such as N,N-diethyl (meth)acrylamide; carboxy group-containing monomers such as AA and MAA; and hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate. These functional group-containing monomers can be used alone or in combination of two or more. When a functional group-containing monomer is used, the ratio of the functional group-containing monomer to the total monomer components constituting the acrylic oligomer can be, for example, 1% by weight or more, 2% by weight or more, or 3% by weight or more, and can be, for example, 15% by weight or less, 10% by weight or less, or 7% by weight or less. The acrylic oligomer may not use a functional group-containing monomer.

[0108] Suitable acrylic oligomers include, for example, homopolymers of dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), 1-adamantyl methacrylate (ADMA), and 1-adamantyl acrylate (ADA), as well as copolymers of DCPMA and MMA, copolymers of DCPMA and IBXMA, copolymers of ADA and methyl methacrylate (MMA), copolymers of CHMA and isobutyl methacrylate (IBMA), copolymers of CHMA and IBXMA, copolymers of CHMA and acryloylmorpholine (ACMO), copolymers of CHMA and diethylacrylamide (DEAA), and copolymers of CHMA and AA.

[0109] The acrylic oligomer can be formed by polymerizing its constituent monomer components. The polymerization method and polymerization mode are not particularly limited, and various conventionally known polymerization methods (e.g., solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be used in an appropriate mode. The type of polymerization initiator (e.g., azo-based polymerization initiator) that can be used as necessary is generally as exemplified for the synthesis of the acrylic polymer (A), and the amount of the polymerization initiator and the amount of the chain transfer agent (e.g., mercaptans) that is optionally used are appropriately set based on technical common sense so as to obtain a desired molecular weight, so detailed explanations are omitted.

[0110] When the adhesive layer or adhesive composition contains an acrylic oligomer, the content can be, for example, 0.01 parts by weight or more relative to 100 parts by weight of the polymer (A), and from the viewpoint of obtaining a higher effect, it may be 0.05 parts by weight or more, 0.1 parts by weight or more, or 0.2 parts by weight or more. From the viewpoint of compatibility with the polymer (A), the content of the acrylic oligomer relative to 100 parts by weight of the polymer (A) is suitably less than 50 parts by weight, preferably less than 30 parts by weight, more preferably 25 parts by weight or less, and may be, for example, 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less. The adhesive layer or adhesive composition may not contain an acrylic oligomer.

[0111] (Crosslinking agent) A crosslinking agent may be used in the pressure-sensitive adhesive layer as necessary. In the technology disclosed herein, the crosslinking agent is typically contained in the pressure-sensitive adhesive layer in a form after crosslinking reaction. By using a crosslinking agent, the cohesive strength of the pressure-sensitive adhesive layer can be appropriately adjusted. In addition, for example, in a pressure-sensitive adhesive layer containing a photoreactive monomer (B), by using a crosslinking agent in combination with the photoreactive monomer (B), it is possible to suitably achieve both the flexibility of the pressure-sensitive adhesive layer before photocuring of the photoreactive monomer and the deformation resistance of the pressure-sensitive adhesive layer after photocuring.

[0112] The type of crosslinking agent is not particularly limited, and can be selected from conventionally known crosslinking agents so that the crosslinking agent exerts an appropriate crosslinking function in the adhesive layer, for example, according to the composition of the adhesive composition. Examples of crosslinking agents that can be used include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, melamine-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, hydrazine-based crosslinking agents, and amine-based crosslinking agents. These can be used alone or in combination of two or more.

[0113] As the isocyanate-based crosslinking agent, a polyfunctional isocyanate compound having two or more functionalities can be used. For example, aromatic isocyanates such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, diphenylmethane diisocyanate, etc., alicyclic isocyanates such as isophorone diisocyanate, etc., aliphatic isocyanates such as hexamethylene diisocyanate, etc. can be mentioned. Examples of commercially available products include isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, product name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, product name "Coronate HL"), an isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate HX"), and trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-110N").

[0114] As the epoxy crosslinking agent, those having two or more epoxy groups in one molecule can be used without any particular limitation. An epoxy crosslinking agent having 3 to 5 epoxy groups in one molecule is preferable. Specific examples of the epoxy crosslinking agent include N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, and the like. Commercially available epoxy crosslinking agents include Mitsubishi Gas Chemical Company's product names "TETRAD-X" and "TETRAD-C", DIC Corporation's product name "Epicron CR-5L", Nagase ChemteX Corporation's product name "Denacol EX-512", Nissan Chemical Industries' product name "TEPIC-G", and the like.

[0115] As the oxazoline-based crosslinking agent, any agent having one or more oxazoline groups in one molecule can be used without any particular limitation. Examples of the aziridine crosslinking agent include trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-(1-(2-methyl)aziridinylpropionate)], and the like. As the carbodiimide crosslinking agent, a low molecular weight compound or a high molecular weight compound having two or more carbodiimide groups can be used.

[0116] In some embodiments, peroxides may be used as crosslinking agents. Examples of peroxides include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroylperoxide, di-n-octanoylperoxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate, and dibenzoylperoxide. Among these, examples of peroxides that are particularly excellent in crosslinking reaction efficiency include di(4-t-butylcyclohexyl)peroxydicarbonate, dilauroylperoxide, and dibenzoylperoxide. In addition, when peroxides are used as the polymerization initiator, it is also possible to use the remaining peroxides that are not used in the polymerization reaction in the crosslinking reaction. In this case, the remaining amount of peroxide is quantified, and if the ratio of peroxide is less than the predetermined amount, peroxide is added as necessary to reach the predetermined amount. The amount of peroxide can be quantified by the method described in Japanese Patent No. 4971517.

[0117] When a crosslinking agent is used, the amount used (when two or more crosslinking agents are used, the total amount of the crosslinking agents) is not particularly limited. From the viewpoint of realizing a pressure-sensitive adhesive that exhibits adhesive properties such as adhesive strength and cohesive strength in a well-balanced manner, the amount of the crosslinking agent used is suitably about 5 parts by weight or less relative to 100 parts by weight of the polymer (A), and may be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or less than 1 part by weight. In an embodiment in which a crosslinking agent and a photoreactive monomer (B) are used in combination, from the viewpoint of favorably exhibiting the effects of such combined use, the amount of the crosslinking agent used relative to 100 parts by weight of the polymer (A) may be, for example, 0.80 parts by weight or less, 0.60 parts by weight or less, 0.30 parts by weight or less, or 0.10 parts by weight or less. The lower limit of the amount of the crosslinking agent used is not particularly limited, and it may be used in an amount greater than 0 parts by weight relative to 100 parts by weight of the polymer (A). In some embodiments, the amount of the crosslinking agent used can be, for example, 0.001 parts by weight or more, optionally 0.01 parts by weight or more, or optionally 0.03 parts by weight or more, relative to 100 parts by weight of the polymer (A).

[0118] The technology disclosed herein can be preferably implemented in an embodiment using at least an isocyanate-based crosslinking agent as a crosslinking agent. The isocyanate-based crosslinking agent may be used in combination with other crosslinking agents. In an embodiment using an isocyanate-based crosslinking agent, the amount of the isocyanate-based crosslinking agent used relative to 100 parts by weight of the polymer (A) may be, for example, 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.03 parts by weight or more. In addition, the amount of the isocyanate-based crosslinking agent used relative to 100 parts by weight of the polymer (A) may be, for example, 10 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, less than 2 parts by weight, less than 1 part by weight, less than 0.80 parts by weight, less than 0.60 parts by weight, less than 0.30 parts by weight, less than 0.10 parts by weight, or less than 0.08 parts by weight.

[0119] A crosslinking catalyst may be used to promote the crosslinking reaction more effectively. Examples of the crosslinking catalyst include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, nursem ferric, butyltin oxide, and dioctyltin dilaurate. Among them, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred. The amount of the crosslinking catalyst used is not particularly limited. The amount of the crosslinking catalyst used can be, for example, about 0.0001 parts by weight or more, about 0.001 parts by weight or more, about 0.005 parts by weight or more, and about 1 part by weight or less, about 0.1 parts by weight or less, about 0.05 parts by weight or less, relative to 100 parts by weight of the polymer (A).

[0120] The adhesive composition used for forming the adhesive layer can contain a compound that generates keto-enol tautomerism as a crosslinking retarder, if desired. For example, a compound that generates keto-enol tautomerism can be preferably used in an adhesive composition that contains an isocyanate-based crosslinking agent or an adhesive composition that can be used by blending an isocyanate-based crosslinking agent. This can provide the effect of extending the pot life of the adhesive composition. As the compound that generates keto-enol tautomerism, various β-dicarbonyl compounds can be used. Specific examples include β-diketones such as acetylacetone and 2,4-hexanedione; acetoacetates such as methyl acetoacetate and ethyl acetoacetate; propionyl acetates such as ethyl propionyl acetate; isobutyryl acetates such as ethyl isobutyryl acetate; malonates such as methyl malonate and ethyl malonate; and the like. Among them, acetylacetone and acetoacetates are preferred. The compound that generates keto-enol tautomerism can be used alone or in combination of two or more. The amount of the compound that causes keto-enol tautomerization used may be, for example, 0.1 parts by weight or more and 20 parts by weight or less, and appropriately 0.5 parts by weight or more and 15 parts by weight or less, for example, 1 part by weight or more and 10 parts by weight or less, or may be 1 part by weight or more and 5 parts by weight or less, relative to 100 parts by weight of polymer (A).

[0121] (Silane coupling agent) The adhesive layer disclosed herein may contain a silane coupling agent if desired. The use of a silane coupling agent may improve the peel strength of the adhesive layer from an adherend (e.g., a glass plate). The adhesive layer containing a silane coupling agent may be suitably formed using an adhesive composition containing a silane coupling agent. In such an adhesive composition, the silane coupling agent is preferably contained in the adhesive composition in a free form from the viewpoint of gelation inhibition and the like. In some embodiments, the silane coupling agent is preferably contained in the adhesive layer disclosed herein in a free form. The silane coupling agent contained in the adhesive layer in such a form can effectively contribute to improving the peel strength. Here, the term "free form" refers to the silane coupling agent not being chemically bonded to other components contained in the adhesive composition or the adhesive layer.

[0122] Examples of the silane coupling agent include silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; silicon compounds containing amino groups such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; silane coupling agents containing (meth)acrylic groups such as acetoacetyl group-containing trimethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane; and silane coupling agents containing isocyanate groups such as 3-isocyanatepropyltriethoxysilane. In some embodiments, the above-mentioned effects can be more preferably achieved by adopting a silane coupling agent having a trialkoxysilyl group. Among these, preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane.

[0123] The amount of the silane coupling agent used when using it can be set so as to obtain the desired effect of use, and is not particularly limited. In some embodiments, the amount of the silane coupling agent used may be, for example, 0.001 parts by weight or more relative to 100 parts by weight of the polymer (A), and from the viewpoint of obtaining a higher effect, it may be 0.01 parts by weight or more, 0.05 parts by weight or more, or 0.1 parts by weight or more. In addition, from the viewpoint of suppressing gelation of the pressure-sensitive adhesive composition, the amount of the silane coupling agent used relative to 100 parts by weight of the polymer (A) is suitably 3 parts by weight or less, may be 1 part by weight or less, or may be 0.5 parts by weight or less.

[0124] (Photopolymerization initiator) The adhesive layer disclosed herein may contain a photopolymerization initiator as necessary for the purpose of improving or imparting photocurability. As the photopolymerization initiator, a ketal-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, etc., may be used, as well as the photopolymerization initiators exemplified as those usable in the synthesis of the polymer (A). The photopolymerization initiator may be used alone or in appropriate combination of two or more.

[0125] Specific examples of ketal-based photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethan-1-one and the like. Specific examples of acetophenone-based photopolymerization initiators include 1-hydroxycyclohexyl-phenyl-ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methoxyacetophenone, and the like. Specific examples of the benzoin ether-based photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, and substituted benzoin ethers such as anisole methyl ether. Specific examples of the acylphosphine oxide photopolymerization initiator include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and the like. Specific examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, etc. Specific examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride, etc. Specific examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime, etc. Specific examples of benzoin-based photopolymerization initiators include benzoin, etc. Specific examples of benzyl-based photopolymerization initiators include benzyl, etc. Specific examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Specific examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

[0126] The content of the photopolymerization initiator in the adhesive layer is not particularly limited and can be set so that the desired effect is appropriately exhibited. In some embodiments, the content of the photopolymerization initiator can be, for example, about 0.005 parts by weight or more, suitably 0.01 parts by weight or more, preferably 0.05 parts by weight or more, may be 0.10 parts by weight or more, may be 0.15 parts by weight or more, or may be 0.20 parts by weight or more, relative to 100 parts by weight of the polymer (A) contained in the adhesive layer. The photocuring property of the adhesive layer tends to improve by increasing the content of the photopolymerization initiator. In addition, the content of the photopolymerization initiator relative to 100 parts by weight of the polymer (A) is suitably 10 parts by weight or less, preferably 7 parts by weight or less, may be 5 parts by weight or less, 3 parts by weight or less, may be 2 parts by weight or less, or may be 1 part by weight or less. It may be advantageous from the viewpoint of improving storage stability (for example, stability against photodegradation) if the content of the photopolymerization initiator is not too high.

[0127] The adhesive layer containing a photopolymerization initiator can typically be formed using an adhesive composition (e.g., a solvent-based adhesive composition) containing the photopolymerization initiator. The adhesive composition containing a photopolymerization initiator can be prepared, for example, by mixing the photopolymerization initiator with other components used in the composition. In addition, when preparing an adhesive composition using a polymer (A) (e.g., an acrylic polymer (A)) synthesized (photopolymerized) in the presence of a photopolymerization initiator, the residue (unreacted material) of the photopolymerization initiator used in synthesizing the polymer (A) may be used as part or all of the photopolymerization initiator contained in the adhesive layer. The same applies when an acrylic oligomer synthesized in the presence of a photopolymerization initiator is used as the acrylic oligomer used as needed. From the viewpoint of ease of production management, the adhesive layer disclosed herein can be preferably formed using an adhesive composition prepared by newly adding the above-mentioned amount of photopolymerization initiator to other components.

[0128] The adhesive layer or adhesive composition disclosed herein may contain, as necessary, various additives common in the field of adhesives, such as tackifier resins (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based, etc. tackifier resins), viscosity adjusters (e.g., thickeners), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, antiaging agents, etc., as other optional components. As for such various additives, those conventionally known can be used in the usual manner, and they do not particularly characterize the present invention, so detailed explanations are omitted. The technology disclosed herein can exhibit good adhesive strength without using the tackifier resin. Therefore, in some embodiments, the content of the tackifier resin in the pressure-sensitive adhesive layer or pressure-sensitive adhesive composition can be, for example, less than 10 parts by weight, or even less than 5 parts by weight, relative to 100 parts by weight of the polymer (A). The content of the tackifier resin can be less than 1 part by weight (for example, less than 0.5 parts by weight), or less than 0.1 parts by weight (0 parts by weight or more and less than 0.1 parts by weight). The pressure-sensitive adhesive layer or pressure-sensitive adhesive composition can be one that does not contain a tackifier resin.

[0129] From the viewpoint of transparency, it is preferable that the amount of components other than the polymer (A) and the photoreactive monomer (B) used as necessary in the pressure-sensitive adhesive layer (and thus the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer) is limited. In the technology disclosed herein, the amount of components other than the polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer is, for example, about 30% by weight or less, suitably about 15% by weight or less, and preferably about 12% by weight or less (for example, about 10% by weight or less). In some embodiments, the amount of components other than the polymer (A) and the photoreactive monomer (B) in the pressure-sensitive adhesive layer may be about 5% by weight or less, about 3% by weight or less, or about 1.5% by weight or less (for example, about 1% by weight or less).

[0130] <Form of Pressure-Sensitive Adhesive Composition> The adhesive layer can be formed using an adhesive composition containing the monomer components of the above-mentioned composition in the form of a polymer, an unpolymerized product (i.e., a form in which the polymerizable functional group is unreacted), or a mixture thereof. The adhesive composition can be in various forms, such as a composition containing an adhesive (adhesive component) in an organic solvent (solvent-based adhesive composition), a composition in the form in which an adhesive is dispersed in an aqueous solvent (water-dispersed adhesive composition), a composition prepared to form an adhesive by curing with active energy rays such as ultraviolet rays or radiation (active energy ray-curable adhesive composition), and a hot melt adhesive composition that is applied in a heated and molten state and forms an adhesive when cooled to around room temperature. From the viewpoint of ease of preparation of the adhesive composition and ease of formation of the adhesive layer, a solvent-based adhesive composition can be preferably adopted in some embodiments. The solvent-based adhesive composition can be preferably prepared using a polymer (A) that is a polymer obtained by solution polymerization of a monomer component.

[0131] In this specification, the term "active energy rays" refers to energy rays having energy capable of inducing chemical reactions such as polymerization reactions, crosslinking reactions, decomposition of initiators, etc. Examples of active energy rays include light such as ultraviolet rays, visible light, and infrared rays, and radiation such as α rays, β rays, γ rays, electron beams, neutron beams, and X-rays.

[0132] The pressure-sensitive adhesive composition typically contains at least a part of the monomer components of the composition (which may be a part of the type of monomer or a part of the amount) in the form of a polymer. The polymerization method for forming the polymer is not particularly limited, and various conventionally known polymerization methods can be appropriately adopted. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization (typically carried out in the presence of a thermal polymerization initiator); photopolymerization carried out by irradiating light such as ultraviolet light (typically carried out in the presence of a photopolymerization initiator); radiation polymerization carried out by irradiating radiation such as β-rays and γ-rays; and the like can be appropriately adopted. In these polymerization methods, the mode of polymerization is not particularly limited, and the polymerization can be carried out by appropriately selecting a conventionally known monomer supply method, polymerization conditions (temperature, time, pressure, light irradiation amount, radiation irradiation amount, etc.), and materials used other than the monomer (polymerization initiator, surfactant, etc.), etc.

[0133] In the polymerization, a known or commonly used photopolymerization initiator or thermal polymerization initiator can be used depending on the polymerization method, polymerization mode, etc. Examples of photopolymerization initiators and thermal polymerization initiators are as described above, so duplicated explanations will be omitted. Such polymerization initiators can be used alone or in appropriate combination of two or more types.

[0134] (Adhesive composition containing polymerized and unpolymerized monomer components) The pressure-sensitive adhesive composition according to some embodiments contains a polymerization product of a monomer mixture containing at least a part of the monomer components (raw material monomers) of the composition. Typically, the composition contains a part of the monomer components in the form of a polymer, and the remaining part in the form of an unpolymerized product (unreacted monomer). The polymerization product of the monomer mixture can be prepared by at least partially polymerizing the monomer mixture. The polymerization reaction product is preferably a partial polymer of the monomer mixture. Such a partial polymer is a mixture of a polymer derived from the monomer mixture and an unreacted monomer, and typically has a syrup-like appearance (viscous liquid). Hereinafter, a partial polymer having such properties may be referred to as "monomer syrup", "polymer syrup", or simply as "syrup".

[0135] The polymerization method for obtaining the polymerization reaction product is not particularly limited, and various polymerization methods as described above can be appropriately selected and used. From the viewpoint of efficiency and simplicity, a photopolymerization method can be preferably adopted. According to photopolymerization, the polymerization conversion rate of the monomer mixture can be easily controlled by the polymerization conditions such as the amount of light irradiation (light amount).

[0136] The polymerization conversion rate of the monomer mixture in the partial polymer is not particularly limited. The polymerization conversion rate can be, for example, about 70% by weight or less, and is preferably about 60% by weight or less. From the viewpoint of ease of preparation and coatability of the adhesive composition containing the partial polymer, the polymerization conversion rate is suitably about 50% by weight or less, and is preferably about 40% by weight or less (for example, about 35% by weight or less). The lower limit of the polymerization conversion rate is not particularly limited, but is typically about 1% by weight or more, and is suitably about 5% by weight or more.

[0137] The adhesive composition containing the partial polymer of the monomer mixture can be easily obtained, for example, by partially polymerizing the monomer mixture containing all of the raw material monomers by an appropriate polymerization method (for example, photopolymerization method). The adhesive composition containing the partial polymer may contain other components (for example, photopolymerization initiator, polyfunctional monomer, crosslinking agent, acrylic oligomer described later, etc.) that are used as necessary. The method of adding such other components is not particularly limited, and for example, they may be contained in the monomer mixture in advance, or may be added to the partial polymer.

[0138] The adhesive composition disclosed herein may be in a form in which a complete polymer of a monomer mixture containing some types of monomers among the monomer components (raw monomers) is dissolved in the remaining types of monomers or their partial polymers. Such a form of adhesive composition is also included in the examples of adhesive compositions containing polymerized and unpolymerized monomers of the monomer components. In this specification, the term "completely polymerized" refers to a polymerization conversion rate of more than 95% by weight.

[0139] A photopolymerization method can be preferably adopted as a curing method (polymerization method) when forming an adhesive from an adhesive composition containing a polymerized product and an unpolymerized product of a monomer component. In an adhesive composition containing a polymerization reactant prepared by a photopolymerization method, it is particularly preferable to adopt a photopolymerization method as a curing method. Since the polymerization reactant obtained by the photopolymerization method already contains a photopolymerization initiator, when the adhesive composition containing this polymerization reactant is further cured to form an adhesive, it can be photocured without adding a new photopolymerization initiator. Alternatively, the adhesive composition may be a composition in which a photopolymerization initiator is added as necessary to the polymerization reactant prepared by the photopolymerization method. The photopolymerization initiator to be added may be the same as or different from the photopolymerization initiator used in preparing the polymerization reactant. An adhesive composition prepared by a method other than photopolymerization can be made photocurable by adding a photopolymerization initiator. A photocurable adhesive composition has the advantage that even a thick adhesive layer can be easily formed. In some preferred embodiments, photopolymerization when forming an adhesive from the adhesive composition can be performed by ultraviolet irradiation. For the ultraviolet irradiation, a known high pressure mercury lamp, low pressure mercury lamp, metal halide lamp, or the like can be used.

[0140] (Adhesive composition containing monomer component in the form of a completely polymerized product) A PSA composition according to some other embodiments contains a monomer component of the PSA composition in the form of a complete polymer. Such a PSA composition may be in the form of, for example, a solvent-based PSA composition containing an acrylic polymer, which is a complete polymer of the monomer component, in an organic solvent, or an aqueous dispersion-based PSA composition in which the acrylic polymer is dispersed in an aqueous solvent.

[0141] (Formation of adhesive layer) The method of forming the adhesive layer is not particularly limited. For example, an adhesive composition is applied to the release surface of a release film and dried (e.g., dried by heating) or cured to form an adhesive layer on the release surface. Alternatively, an adhesive composition sandwiched between two release films can be dried or cured to form an adhesive layer. The curing treatment may include crosslinking (e.g., crosslinking by the reaction of the crosslinking agent described above), cooling, etc. When two or more types of curing treatments are performed, they can be performed simultaneously or stepwise. As a method for applying the adhesive composition, various conventionally known methods can be used. Specific examples include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, extrusion coating using a die coater, etc. As the release surface, a release film having a highly smooth release surface in which the maximum height (Rz) or arithmetic mean roughness (Ra) is typically limited to a predetermined value or less can be used to stably (reproducibly) produce a highly smooth adhesive surface. The pressure-sensitive adhesive composition is preferably applied at 80° C. or lower, and more preferably at 60° C. or lower (e.g., 40° C. or lower), which can suppress roughening of the pressure-sensitive adhesive layer due to the difference in thermal expansion coefficient between the release film and the pressure-sensitive adhesive layer, and can form a smoother adhesive surface.

[0142] (Adhesive layer thickness) The thickness of the adhesive layer is not particularly limited. The thickness of the adhesive layer may be, for example, about 1 μm to 500 μm, and may be, for example, about 3 μm to 500 μm. In some embodiments, the thickness of the adhesive layer is suitably 5 μm or more, and may be, for example, 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and may be more than 25 μm. When the thickness of the adhesive layer is large, the stress dispersion ability of the adhesive layer tends to be high. This can advantageously contribute to reducing optical distortion. In addition, a thick adhesive layer tends to have excellent step conformability and easily absorbs deformation caused by foreign matter, etc. Impact resistance also tends to be improved. The technology disclosed herein can be preferably implemented in an embodiment in which the thickness of the adhesive layer is, for example, 30 μm or more. The thickness of the adhesive layer may be 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 75 μm or more, or 90 μm or more. On the other hand, when the thickness of the adhesive layer is large, the optical path passing through the adhesive layer is also long, so that optical distortion is easily recognized. For this reason, in some embodiments, the thickness of the adhesive layer is suitably set to, for example, 200 μm or less, and may be 150 μm or less, 120 μm or less, preferably 100 μm or less, more preferably 70 μm or less, even more preferably 50 μm or less, and may be 35 μm or less. An adhesive layer having such a thickness can be one in which deformation of the adhesive layer is better suppressed. According to the technology disclosed herein, a bond having high deformation resistance and high impact resistance can be formed in a configuration including an adhesive layer having a thickness of, for example, 70 μm or less. The thickness of the adhesive layer can be measured with a 1 / 1000 mm scale dial gauge of a flat probe.

[0143] (Tan δ peak top temperature) The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer disclosed herein preferably has a peak top temperature of its loss tangent tan δ in the range of -50°C to 0°C. A pressure-sensitive adhesive having a peak top of tan δ in the low temperature region is likely to provide good impact resistance. The peak top temperature of the loss tangent tan δ of the pressure-sensitive adhesive can be determined by the following method. That is, dynamic viscoelasticity measurement is carried out under the same conditions as the measurement of the 25°C storage modulus described below, and the storage modulus G' and loss modulus G" are measured. The loss tangent tan δ is then calculated by the following formula: tan δ=G" / G'; and the temperature dependency is plotted, whereby the temperature corresponding to the peak top (the temperature at which the tan δ curve is maximum) can be determined.

[0144] (25℃ storage modulus) The storage modulus at 25°C (25°C storage modulus) of the adhesive layer is appropriately set depending on the purpose and mode of use, and is not limited to a specific range. From the viewpoint of adhesive properties such as deformation resistance and heat resistance, the above-mentioned 25°C storage modulus is about 4×10 4 It is appropriate to set the pressure to 6×10 Pa or more, and preferably to 6×10 4 Pa or more, more preferably about 8×10 4 Pa or more, approximately 1.0×10 5 Pa or more, and is approximately 1.2×10 5 Pa or more is acceptable, approximately 1.5×10 5 Pa or more is sufficient, approximately 1.8×10 5 The pressure-sensitive adhesive layer having a high storage modulus at 25° C. tends to have excellent resistance to deformation under pressure. 7 Pa or less, approximately 1×10 6 From the viewpoint of suitably exhibiting adhesive properties such as adhesion, the storage modulus at 25° C. is preferably about 5.0×10 Pa or less. 5 Pa or less, more preferably about 3.0×10 5 Pa or less, and more preferably about 2.0×10 5 Pa or less, approximately 1.4×10 5 Pa or less, and may be approximately 1.0×10 5The storage modulus at 25°C may be equal to or less than 1 Pa. The storage modulus at 25°C can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc. of the base polymer. The storage modulus at 25°C is measured by the following method. The same applies to the examples described later.

[0145] [Storage modulus at 25℃] A pressure-sensitive adhesive layer with a thickness of about 2 mm is prepared by stacking several layers of the pressure-sensitive adhesive layer to be measured. A sample is punched out from this pressure-sensitive adhesive layer into a disk shape with a diameter of 7.9 mm, which is sandwiched between parallel plates and fixed. Dynamic viscoelasticity is measured under the following conditions using a viscoelasticity tester (e.g., ARES or equivalent, manufactured by TA Instruments) to determine the storage modulus G´ (25°C) [Pa] at 25°C. Measurement mode: Shear mode Temperature range: -70℃~150℃ Heating rate: 5℃ / min ·Measurement frequency: 1Hz

[0146] (Gel fraction) The gel fraction of the adhesive layer is appropriately set according to the purpose of use, the mode of use, etc., and is not limited to a specific range. The gel fraction is, for example, about 99% by weight or less, and is suitably about 97% by weight or less. From the viewpoint of step conformability, etc., in some preferred embodiments, the gel fraction is about 95% by weight or less, more preferably about 92% by weight or less, and may be about 88% by weight or less, may be about 75% by weight or less, or may be about 65% by weight or less. For example, when a logo mark or other print is formed on the surface of the adherend, the adhesive layer having the gel fraction can well conform to the unevenness of the print without impairing visibility. In addition, from the viewpoint of good adhesive properties and viscoelastic properties, the gel fraction of the adhesive layer is, for example, about 10% by weight or more, and is suitably about 20% by weight or more. From the viewpoint of deformation resistance, the gel fraction is preferably about 30% by weight or more, more preferably about 40% by weight, and may be about 50% by weight or more, about 65% by weight or more, or about 75% by weight or more. The gel fraction can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc. of the base polymer. The gel fraction is measured by the following method. The same applies to the examples described later.

[0147] [Gel fraction] A predetermined amount of adhesive sample (weight Wg1) is wrapped in a porous polytetrafluoroethylene film (weight Wg2) with an average pore size of 0.2 μm in a purse shape, and the opening is tied with string (weight Wg3). As the porous polytetrafluoroethylene (PTFE) film, the product name "Nitoflon (registered trademark) NTF1122" (average pore size 0.2 μm, porosity 75%, thickness 85 μm) available from Nitto Denko Corporation or an equivalent product is used. The package is immersed in a sufficient amount of ethyl acetate and kept at room temperature (typically 23° C.) for 7 days to elute only the sol component in the adhesive layer outside the film, and then the package is taken out and the ethyl acetate adhering to the outer surface is wiped off, the package is dried at 130° C. for 2 hours, and the weight (Wg4) of the package is measured. The gel fraction of the adhesive layer is calculated by substituting each value into the following formula. Gel fraction (%) = [(Wg4-Wg2-Wg3) / Wg1] x 100

[0148] (Total light transmittance) In some embodiments, the total light transmittance of the pressure-sensitive adhesive layer is, for example, about 50% or more, and is suitably about 70% or more. In terms of visibility of the decorative film through the pressure-sensitive adhesive layer, in some preferred embodiments, the total light transmittance of the pressure-sensitive adhesive layer is about 85% or more, more preferably about 90% or more. Theoretically, the upper limit of the total light transmittance is a value obtained by subtracting the light loss (Fresnel loss) caused by reflection at the air interface from 100%, and in practice, it may be about 95% or less, or about 94% or less (for example, 93% or less). Even with a pressure-sensitive adhesive layer having such a total light transmittance, good visibility through the pressure-sensitive adhesive layer can be obtained.

[0149] (Haze value) In some embodiments, the haze value of the adhesive layer is, for example, about 10% or less, and is suitably about 3% or less. In some preferred embodiments, from the viewpoint of visibility through the adhesive layer, the haze value of the adhesive layer is about 1% or less, more preferably about 0.8% or less, and even more preferably 0.5% or less. The lower limit of the haze value is theoretically 0%, and may be more than about 0.0% in practice.

[0150] The total light transmittance and haze value of the pressure-sensitive adhesive layer can be adjusted by the composition (type of base polymer and added components), thickness, etc. of the pressure-sensitive adhesive layer.

[0151] The total light transmittance and haze value of the adhesive layer can be measured by attaching the adhesive layer to one side of a glass plate and using a haze meter. The haze meter can be an instrument named "HM-150N" manufactured by Murakami Color Research Laboratory or an equivalent. Specifically, the measurements are performed by the method described in the Examples below.

[0152] The pressure-sensitive adhesive layer having the total light transmittance and haze value as described above may be a colored transparent or colorless transparent pressure-sensitive adhesive layer. In addition, the optical distortion reducing effect of the pressure-sensitive adhesive layer according to the technology disclosed herein can be exhibited in a configuration in which at least a part of the pressure-sensitive adhesive layer surface has transparency to such an extent that it is possible to see through the pressure-sensitive adhesive layer, so the pressure-sensitive adhesive layer does not need to be transparent or translucent.

[0153] (Surface properties of adhesive surface) The adhesive layer disclosed herein preferably has an adhesive surface (including the first adhesive surface and the second adhesive surface; the same applies hereinafter unless otherwise specified) whose maximum height Rz is limited to a predetermined value or less. A configuration having an adhesive surface designed to have a low maximum height Rz can have high surface smoothness and can have no optical distortion or suppressed optical distortion. Such an adhesive layer can not impair the design of the adherend, for example, its aesthetic appearance or luxurious feel, for example, when the decorative film is viewed through the adhesive layer.

[0154] The maximum height Rz of the adhesive surface of the adhesive layer is, for example, about 2000nm or less, and is suitably about 1000nm or less, preferably about 600nm or less, more preferably about 500nm or less, even more preferably about 450nm or less, particularly preferably about 400nm or less, and may be less than 350nm, may be less than 300nm, or may be less than 250nm. From the viewpoint of production efficiency, etc., in some embodiments, the maximum height Rz of the adhesive surface of the adhesive layer may be, for example, about 10nm or more, may be about 50nm or more, may be about 100nm or more, or may be about 200nm or more. The maximum height Rz of the first adhesive surface of the adhesive layer and the maximum height Rz of the second adhesive surface may be about the same or different.

[0155] The adhesive surface of the adhesive layer disclosed herein is preferably limited to a predetermined value or less in arithmetic mean roughness Ra. By providing an adhesive surface designed to have a low arithmetic mean roughness Ra, optical distortion can be easily suppressed to a high degree.

[0156] The arithmetic mean roughness Ra of the adhesive surface of the adhesive layer is, for example, about 300 nm or less, suitably about 150 nm or less, preferably about 70 nm or less, more preferably about 65 nm or less, even more preferably about 55 nm or less, and may be less than 50 nm, may be less than 45 nm, or may be less than 40 nm. From the viewpoint of production efficiency, etc., in some embodiments, the arithmetic mean roughness Ra of the adhesive surface of the adhesive layer may be, for example, about 10 nm or more, may be about 20 nm or more, or may be about 30 nm or more (for example, about 40 nm or more). The arithmetic mean roughness Ra of the first adhesive surface of the adhesive layer and the arithmetic mean roughness Ra of the second adhesive surface may be similar or different.

[0157] The maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the adhesive layer can be adjusted depending on the surface properties of the release film laminated to the adhesive surface before use, the peeling force of the release film from the adhesive layer, the thickness of the adhesive layer, etc.

[0158] In addition, the maximum height Rz and the arithmetic mean roughness Ra of the adhesive surface of the adhesive layer are measured by using a non-contact surface roughness measuring device for the adhesive surface of the adhesive layer after the release film is peeled off. As the non-contact surface roughness measuring device, a surface roughness measuring device of the optical interference type is used, and for example, a three-dimensional optical profiler (trade name "NewView7300", manufactured by ZYGO) or its equivalent can be used. The specific measurement operation and measurement conditions can be set according to the measurement conditions described in the examples below, or to obtain results equivalent to or corresponding to those obtained by following the measurement conditions.

[0159] (Adhesion to transparent materials) The adhesive strength of the adhesive layer disclosed herein is not particularly limited and may be set according to the purpose. In some embodiments, the adhesive strength of the adhesive layer to the transparent member is, for example, about 1.0 N / 20 mm or more, and may be about 3.0 N / 20 mm or more (for example, about 5.0 N / 20 mm or more). In other words, it can be said that the adhesive layer is adhered to the transparent member with the above adhesive strength. By thus providing good adhesion between the transparent member and the adhesive layer, the laminate can exhibit good durability against impact and the like. From the viewpoint of bonding reliability, the adhesive strength is preferably about 7.0 N / 20 mm or more, more preferably about 8.0 N / 20 mm or more, even more preferably about 9.0 N / 20 mm or more, and may be about 10.0 N / 20 mm or more, or may be about 11.0 N / 20 mm or more. From the viewpoint of easily achieving a balance with other properties, the adhesive strength may be, for example, about 20 N / 20 mm or less, about 16.0 N / 20 mm or less, or about 12.0 N / 20 mm or less. The adhesive strength can be adjusted by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer.

[0160] The adhesive strength to a transparent member is determined by pressing the adhesive surface to be measured against a transparent member (e.g., a glass plate) by rolling a 2 kg rubber roller back and forth once, and measuring the peel strength when peeling the adhesive layer from the transparent member at a peel angle of 180 degrees and a tensile speed of 300 mm / min using a tensile tester in an environment of 23°C and 50% RH in accordance with JIS Z 0237. Specifically, the peel strength is measured by the method described in the Examples below.

[0161] (Elastic modulus by tensile test) In some preferred embodiments, the adhesive layer has a modulus of elasticity (also referred to as initial modulus of elasticity) of 3.0 MPa or more in a tensile test. An adhesive layer with a higher modulus of elasticity tends to exhibit better deformation resistance. In an embodiment in which two members (typically a transparent member and a decorative film) are bonded to each other via an adhesive layer in a laminate, the high deformation resistance of the adhesive layer can be useful for precisely maintaining the relative positions of the two members. In an embodiment in which a decorative film and a transparent member are bonded to each other via an adhesive layer, for example, the high deformation resistance of the adhesive layer can be useful for suppressing a phenomenon in which the appearance of the laminate changes due to local pressure from the decorative film side (pressure deformation resistance).

[0162] In some preferred embodiments of the pressure-sensitive adhesive layer, the elastic modulus may be, for example, 5.0 MPa or more, 7.0 MPa or more, 10.0 MPa or more, 15.0 MPa or more, or 20.0 MPa or more. The increase in the elastic modulus tends to improve the deformation resistance. The upper limit of the elastic modulus is not particularly limited. From the viewpoint of easily achieving a balance with other properties (for example, one or more properties selected from impact resistance, adhesive strength, haze value, etc.), the elastic modulus is advantageously 150 MPa or less, preferably 120 MPa or less, may be 100 MPa or less, may be 80 MPa or less, or may be 60 MPa or less. The elastic modulus measured by the tensile test can be adjusted by selecting the composition of the pressure-sensitive adhesive layer, etc. The elastic modulus measured by the tensile test is measured by the above-mentioned tensile test. More specifically, it is measured by the method described in the Examples below.

[0163] (Impact resistance) The adhesive layer disclosed herein has an impact resistance of 2.0 J / 10 mm 2 The pressure-sensitive adhesive layer having high impact resistance can form a highly reliable bond. Even if the pressure-sensitive adhesive layer is subjected to an impact due to, for example, a drop or a collision, the pressure-sensitive adhesive layer can withstand the impact and can maintain a good bonded state in the laminate.

[0164] In some preferred embodiments of the pressure-sensitive adhesive layer, the impact resistance is, for example, 2.1 J / 10 mm 2 It may be more than 2.3J / 10mm 2 More than 2.5J / 10mm is fine. 2 More than 2.7J / 10mm is fine. 2 More than 3.0J / 10mm is also acceptable. 2 The laminate disclosed herein has an impact resistance of 3.3 J / 10 mm or more. 2 or more than 3.5J / 10mm 2 The impact resistance may be, for example, 20 J / 10 mm or less. The upper limit of the impact resistance is not particularly limited. From the viewpoint of easily achieving a balance with other properties, the impact resistance may be, for example, 20 J / 10 mm or less. 2 It may be less than 15J / 10mm 2 Less than 10J / 10mm is also acceptable. 2 Less than 8.0J / 10mm is also acceptable. 2 But 6.0J / 10mm 2 The impact resistance can be adjusted by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer. The impact resistance is measured by the above-mentioned shear impact test. More specifically, it is measured by the method described in the examples below.

[0165] In addition, the pressure-sensitive adhesive layer disclosed herein includes an embodiment in which the adhesive layer is photocured after being attached to an adherend, so that at least the photocurable pressure-sensitive adhesive layer (e.g., pressure-sensitive adhesive C in the examples described later) is exposed to light with an illuminance of 300 mW / cm 2 , cumulative light intensity 3000mJ / cm 2 The measurement sample is irradiated with ultraviolet light under the conditions of and aged at 50° C. for 48 hours, and then the peak top temperature of tan δ, the storage modulus at 25° C., the gel fraction, the total light transmittance, the haze value, the maximum height Rz of the adhesive surface, the arithmetic mean roughness Ra, the adhesive strength, the modulus of elasticity by a tensile test, and the impact resistance are measured using the measurement sample. When the release film is transparent, the ultraviolet irradiation treatment is preferably performed in a state where the pressure-sensitive adhesive layer is sandwiched between transparent release films.

[0166] <Second adhesive layer> The technology disclosed herein may be implemented in the form of a laminate including a first adhesive layer and a second adhesive layer, for example, as shown in FIG. 4. The first adhesive layer is disposed between a transparent member and a decorative film, and the second adhesive layer is disposed on the side of the decorative film opposite to the first adhesive layer. In such an embodiment, the first adhesive layer and the second adhesive layer may have the same composition, configuration, characteristics, etc., or may be different. Based on the above explanation, the first adhesive layer and the second adhesive layer can be independently designed to have a composition, configuration, characteristics, etc. suitable for their purpose or use. For example, the second adhesive layer may not require the visibility required for the first adhesive layer due to its arrangement, and may have a composition, configuration, and characteristics different from those of the first adhesive layer. Depending on the characteristics required for the arrangement, a known or commonly used adhesive may be adopted as the second adhesive layer.

[0167] Although not particularly limited, the second pressure-sensitive adhesive layer may have a lower total light transmittance than the first pressure-sensitive adhesive layer. The second pressure-sensitive adhesive layer may have a higher haze value than the first pressure-sensitive adhesive layer. The second pressure-sensitive adhesive layer may be a colored pressure-sensitive adhesive layer (e.g., a black pressure-sensitive adhesive layer) and may also function as a colored layer. The maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the second pressure-sensitive adhesive layer are not particularly limited, and may be approximately the same as the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the first pressure-sensitive adhesive layer, but may be higher than the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the first pressure-sensitive adhesive layer.

[0168] In an embodiment in which the laminate includes a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer, it is preferable to design the thickness of the second pressure-sensitive adhesive layer to be greater than the thickness of the first pressure-sensitive adhesive layer. By configuring in this way, for example, the deformation resistance including the pressure deformation resistance can be preferably ensured by the second pressure-sensitive adhesive layer. This increases the degree of freedom in designing the first pressure-sensitive adhesive layer disposed on the viewing side of the decorative film, and for example, the first pressure-sensitive adhesive layer can reduce optical distortion, and the second pressure-sensitive adhesive layer can improve the deformation resistance, thereby preferably improving the performance of the laminate as a whole. Although not particularly limited, the thickness of the second pressure-sensitive adhesive layer can be 1.2 times or more (for example, about 1.2 to 5 times) the thickness of the first pressure-sensitive adhesive layer, and may be 1.5 times or more, or even 2 times or more.

[0169] <Attachment of adhesive layer> The method of attaching the adhesive layer disclosed herein to the adherend is not particularly limited. Any known or conventional pressure-bonding method can be adopted according to the purpose and mode of use. In some preferred modes, the adhesive layer may be attached by a method including photocuring the adhesive layer after bonding to the adherend (specifically, a transparent member or a decorative film). A laminate in which the adhesive layer is laminated is formed by bonding the adhesive layer to the adherend (specifically, a transparent member or a decorative film). A laminate including the cured adhesive layer and the adherend (specifically, a transparent member or a decorative film) is obtained by photocuring the adhesive layer. Thus, this specification provides a method for manufacturing a laminate including, in this order, bonding any of the adhesive layers disclosed herein to an adherend (specifically, a transparent member or a decorative film) and irradiating the adhesive layer with ultraviolet light (for example, through a transparent member) to photocur the adhesive layer.

[0170] <Laminated structure of transparent member and adhesive layer> (Total light transmittance) In some embodiments, the total light transmittance of the laminated structure of the transparent member and the adhesive layer is, for example, about 50% or more, and is suitably about 70% or more. In some preferred embodiments, from the viewpoint of visibility of the decorative film through the transparent member and the adhesive layer, the total light transmittance of the laminated structure is about 85% or more, more preferably about 90% or more. The upper limit of the total light transmittance is theoretically 100% minus the light loss (Fresnel loss) due to reflection at the air interface, and in practice may be about 95% or less, and even if it is about 94% or less (for example, 92% or less), good visibility can be obtained through the transparent member and the adhesive layer.

[0171] (Haze value) In some embodiments, the haze value of the laminated structure of the transparent member and the adhesive layer is, for example, about 10% or less, and is suitably about 3% or less. In some preferred embodiments, from the viewpoint of visibility through the transparent member and the adhesive layer, the haze value of the laminated structure is about 1% or less, more preferably about 0.8% or less, and may be 0.5% or less. The lower limit of the haze value is theoretically 0%, and may be more than about 0.0% in practical use.

[0172] The total light transmittance and haze value of the laminated structure of the transparent member and the adhesive layer can be measured using a haze meter, such as the "HM-150N" manufactured by Murakami Color Research Laboratory or an equivalent product.

[0173] <Decorative film> The laminate disclosed herein includes a decorative film. Here, the decorative film refers to a film having a design on its surface (decorated surface), and is also called a design film or a decorative film. The decorative film includes a member that plays a role of decoration and protection while maintaining the visibility of an image display device or an input device. Examples of the decorative film include a film having a decorative layer (printed layer, laminate layer, colored layer, glossy layer, continuous or discontinuous inorganic layer (metal layer, metal oxide layer, etc.)) that imparts a desired appearance. The decorative film can have a design on its surface and exhibit good concealment properties.

[0174] The decorative film may have a decorative layer. Examples of the decorative layer include a print layer, a laminate layer, a colored layer, a glossy layer, a continuous or discontinuous inorganic layer, etc., which impart a desired appearance. Examples of the continuous or discontinuous inorganic layer include a continuous or discontinuous metal layer, a continuous or discontinuous metal oxide layer, a laminate of a continuous or discontinuous metal layer and a metal oxide layer, and a continuous or discontinuous metal / metal oxide composite layer. Examples of the metal include aluminum, zinc, lead, copper, silver, and alloys thereof. Examples of the metal oxide include chromium oxide, indium oxide, zinc oxide, titanium oxide, etc. The metal layer or metal oxide layer can be formed by deposition, sputtering, or the like. A typical example of a decorative film is a metallic film. A metallic decorative film may have electromagnetic wave transparency in addition to metallic luster. Examples of such decorative films include electromagnetic wave-transmitting metallic glossy members as described in JP-A-2018-69462, JP-A-2019-123238, and JP-A-2019-188805.

[0175] In addition, the decorative film may further include a substrate layer and a decorative layer covering at least a part of at least one surface of the substrate layer. As the substrate layer, various resin films such as plastic films may be used. Examples of materials for the plastic film include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, and ethylene-butene copolymer, cellulose resins such as triacetyl cellulose, acetate resins, polysulfone resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, and cyclic polyolefin resins such as norbornene resins, (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, ethylene-vinyl acetate copolymer resins, ethylene-vinyl alcohol copolymer resins, polyarylate resins, and polyphenylene sulfide resins. A film substrate formed from one or a mixture of two or more of these resins can be used. Among them, resin films formed from polyester resins such as PET, polyolefin resins, polycarbonate resins, and (meth)acrylic resins are preferred. The thickness of the substrate layer is not particularly limited, and is, for example, about 5 to 250 μm. The decorative layer may be disposed on the adhesive layer side of the substrate layer, on the opposite side to the adhesive layer, or on both sides of the substrate layer.

[0176] In a decorative film including a decorative layer, the thickness of the decorative layer is preferably within the range of about 1 to 1000 nm, and may be, for example, about 1 to 300 nm, or may be, for example, about 1 to 200 nm. The sheet resistance of the decorative layer is suitably 100 Ω / □ or more, and may be, for example, 250 Ω / □ or more, or may be 1000 Ω / □ or more. A decorative film having such a decorative layer can have radio wave transparency, and can be preferably used in various applications requiring radio wave transparency, such as portable electronic devices. The upper limit of the sheet resistance of the decorative layer is not particularly limited, and may be, for example, 1×10 16 The sheet resistance can be Ω / □ or less. The sheet resistance can be measured based on the eddy current measurement method described in JIS Z 2316. The same method is used in the examples described later.

[0177] In addition, the visible light transmittance of the decorative film is preferably less than 30% from the viewpoint of concealment and light blocking properties, may be less than 20%, preferably less than 10%, and may be 7.0% or less. The lower limit of the visible light transmittance is 0%, may be 1% or more, may be 3% or more. The visible light transmittance of the decorative film can be adjusted by setting the decorative layer of the decorative film, etc. The visible light transmittance of the decorative film is obtained by measuring the transmittance in the visible light region (380 to 780 nm) with a spectrophotometer. It is measured in the same manner in the examples described later.

[0178] The design-forming surface of the decorative film may be flat or may have irregularities due to a printed matter such as a logo mark, an engraved mark, etc. The pressure-sensitive adhesive layer disclosed herein may have excellent step conformability, and therefore can adhere well to the decorative film surface having the irregularities.

[0179] The surface of the decorative film on the side of the adhesive layer may be subjected to a surface treatment such as application of an undercoat agent, corona discharge treatment, plasma treatment, etc. Such a surface treatment can be useful for improving the adhesion between the decorative film and the adhesive layer.

[0180] <Colored layer> The laminate disclosed herein may have one or more colored layers. The colored layer may be disposed between the transparent member and the adhesive layer, between the adhesive layer and the decorative film, or on the side of the decorative film opposite to the adhesive layer. The colored layer may be disposed on the outer surface of the transparent member. A laminate having a colored layer may achieve high concealment properties.

[0181] The colored layer disposed on the laminate is not particularly limited except that it is colored. In some embodiments, the colored layer can be formed by applying a colored layer forming composition containing a colorant and a binder to a transparent member, a pressure-sensitive adhesive layer, or a decorative film. As the colorant, a conventionally known pigment or dye can be used. The color of the colorant can be, for example, black, gray, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearl, white, or the like. Black-based colorants tend to have excellent light-shielding properties, and also tend to have excellent visibility, including machine distinguishability, and design properties. From the viewpoint of obtaining excellent light-shielding properties, the use of black-based colorants is preferable. In that case, the colored layer is also called a black layer.

[0182] As the black colorant, organic or inorganic colorants (pigments, dyes, etc.) can be used. Specific examples of black colorants include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine soot, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complexes, anthraquinone-based colorants, etc. Among these, carbon black is preferable.

[0183] As the binder used in the colored layer, a material known in the field of paint or printing can be used without any particular limitation. Examples include polyurethane, phenolic resin, epoxy resin, urea melamine resin, polymethyl methacrylate, and the like. The composition for forming the colored layer can be, for example, a solvent type, an ultraviolet curing type, a heat curing type, and the like. The colored layer can be formed by adopting a means that has been conventionally adopted for forming a colored layer without any particular limitation. For example, a method of forming a colored layer (printed layer) by printing such as gravure printing, flexographic printing, and offset printing can be preferably adopted.

[0184] The colored layer may be a single layer structure consisting of one layer as a whole, or may be a multilayer structure including two, three or more sub-colored layers. A colored layer having a multilayer structure including two or more sub-colored layers can be formed, for example, by repeatedly applying (for example, printing) a colored layer-forming composition. The color and amount of the colorant contained in each sub-colored layer may be the same or different. For a colored layer for imparting light-shielding properties, it is particularly meaningful to have a multilayer structure from the viewpoint of preventing pinholes from occurring and increasing the reliability of preventing light leakage.

[0185] The colored layer (which may be a printed layer) as described above may be formed over the entire surface of, for example, the surface of a transparent member or the surface of a decorative film, or may be formed partially on the surface. The printed layer is suitable for partial formation. For example, in the laminate shown in Figures 2 to 4, the colored layer (printed layer) may be preferably used as the colored layer 40. The colored layer that is partially arranged may be, for example, text information, a design, or a pattern when viewed from above, and may be formed in a ring shape (frame shape) along the outer edge.

[0186] In some other embodiments, the colored layer is a resin film containing a colorant, and may be, for example, a resin film in which a colorant is mixed in the main constituent material (resin material) of the resin film. The above-mentioned colorant-containing resin film is also called a colored resin film. As the colorant contained in the resin film, the conventionally known pigments and dyes exemplified above can be used. From the viewpoint of hiding power, a black colorant is preferred, and carbon black is particularly preferred. The above-mentioned colored layer is preferably a black layer.

[0187] If necessary, the above-mentioned colored resin film may contain various additives such as fillers (inorganic fillers, organic fillers, etc.), dispersants (surfactants, etc.), antiaging agents, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, etc.

[0188] The colored resin film may have a single layer structure, or may have a multilayer structure of two, three or more layers. From the viewpoint of shape stability, the resin film is preferably a single layer structure. In the case of a multilayer structure, at least one layer (preferably all layers) is preferably a layer having a continuous structure of the resin (resin containing a colorant). The method for producing the resin film is not particularly limited and may be any conventionally known method. For example, conventionally known general film forming methods such as extrusion molding, inflation molding, T-die casting molding, and calendar roll molding may be appropriately used.

[0189] The colored resin film layer as described above can be disposed, for example, on the side opposite to the pressure-sensitive adhesive layer of the decorative film, preferably over the entire surface. For example, in the laminate shown in Figures 3 to 4, a colored resin film layer (for example, a black resin film layer) can be preferably used as the colored layer 50.

[0190] <Other layers> The laminate disclosed herein may have one or more additional layers in addition to the transparent member, adhesive layer, decorative film, and colored layer, depending on the purpose and mode of use. For example, additional layers such as an undercoat layer for improving interlayer adhesion, an easy-adhesion layer, an ultraviolet absorbing layer, and an anti-blocking layer may be disposed between each layer (transparent member, adhesive layer, decorative film, colored layer, etc.). In addition, a layer such as a hard coat layer, an anti-reflection layer, and an anti-fouling / anti-fingerprint coat layer may be provided on the side of the transparent member opposite to the adhesive layer.

[0191] <Application> The use of the laminate disclosed herein is not particularly limited. It can be used in various applications to which a laminate having a transparent member and a decorative film can be applied. The laminate disclosed herein can be preferably used in a portable electronic device. For example, in a portable electronic device, it can be preferably used as a laminate including a transparent housing as a transparent member. With such a configuration, the decorative surface of the decorative film can be seen from the outside of the housing, while, for example, a configuration having a colored layer can have internal concealment properties, making it particularly suitable as an exterior structure such as a case.

[0192] Non-limiting examples of the portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (for example, wristwear-type devices worn on the wrist like a wristwatch, modular-type devices worn on a part of the body with a clip or strap, eyewear-type devices including glasses-type devices (monocular and binocular types, including head-mounted types), clothing-type devices attached to shirts, socks, hats, etc. in the form of accessories, earwear-type devices attached to the ears like earphones, etc.), digital cameras, digital video cameras, audio devices (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game devices, electronic dictionaries, electronic organizers, electronic books, in-vehicle information devices, portable radios, portable televisions, portable printers, portable scanners, portable modems, etc. In this specification, "portable" does not mean that it is sufficient to simply be portable, but rather that it has a level of portability that allows an individual (average adult) to carry it relatively easily.

[0193] The matters disclosed in this specification include the following. [1] A laminate having a transparent member, an adhesive layer, and a decorative film arranged in this order. [2] The laminate according to the above [1], wherein the visible light transmittance in the lamination direction of the transparent member, the pressure-sensitive adhesive layer and the decorative film is less than 10%. [3] The laminate according to the above [1] or [2], wherein the pressure-sensitive adhesive layer has a surface with an arithmetic mean roughness Ra of 70 nm or less and a maximum height Rz of 600 nm or less. [4] The laminate according to any one of the above [1] to [3], wherein the pressure-sensitive adhesive layer has a total light transmittance in the lamination direction of 85% or more and a haze value of 1% or less. [5] The pressure-sensitive adhesive layer has a storage modulus of 4×10 at 25° C. 4 The laminate according to any one of the above [1] to [4], having a compressive strength of 100 Pa or more. [6] The laminate according to any one of the above [1] to [5], wherein the pressure-sensitive adhesive layer is adhered to the transparent member with a 180 degree peel strength of more than 7 N / 20 mm. [7] The laminate according to any one of the above [1] to [6], wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer. [8] The laminate according to any one of the above [1] to [7], wherein the pressure-sensitive adhesive layer has an elastic modulus of 3.0 MPa or more as measured by the following tensile test. [Tensile test] The adhesive layer was exposed to an illumination intensity of 300 mW / cm 2 , Accumulated light intensity 3000mJ / cm 2 After aging at 50° C. for 48 hours, the pressure-sensitive adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test piece. A tensile test is performed on the test piece using a tensile tester under conditions of 23° C., 50% RH, 120 mm between-chuck distance, and 50 mm / min tensile speed to obtain a stress-displacement curve, and the elastic modulus [MPa] is calculated from the initial slope. [9] The pressure-sensitive adhesive layer has an impact resistance of 2.0 J / 10 mm as measured by the following shear impact test. 2The laminate according to any one of the above items [1] to [8]. [Shear impact test] A shear impact test is performed using a pendulum-type adhesive shear impact tester based on JIS K6855. As a measurement sample, the first surface of the pressure-sensitive adhesive layer, which is 10 mm square, is attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then the second surface of the pressure-sensitive adhesive layer is attached to the center of a 40 mm square stainless steel plate (SUS304BA plate) and pressed with a load of 5 N for 10 seconds, and then autoclaved (50°C, 0.5 MPa, 15 minutes), and the illuminance from the glass plate side is 300 mW / cm. 2 , Accumulated light intensity 3000mJ / cm 2 After irradiating ultraviolet light under the above conditions, the film is aged at 50°C for 48 hours before use. The measurement sample was fixed so that the stainless steel plate was on the bottom side, and a hammer was applied to the outer peripheral side of the glass plate at a hammer energy of 2.75 J and a hammer speed of 3.5 m / sec in an environment of 23°C and 50% RH. The absorbed energy [J] was measured to determine the impact resistance [J / 10 mm 2 ] is required.

[10] The laminate according to any one of the above [1] to [9], wherein the pressure-sensitive adhesive layer contains a polymer (A) and a photoreactive monomer (B).

[11] The laminate according to

[10] above, wherein the photoreactive monomer (B) contains a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule, and the compound B1 has a molecular weight per one of the ethylenically unsaturated groups of 100 g / mol or more.

[12] The laminate according to any one of the above [1] to

[11] , wherein the decorative film has a base layer and a decorative layer covering at least a portion of at least one surface of the base layer, and the thickness of the decorative layer is within the range of 1 to 1000 nm.

[13] The laminate according to

[12] above, wherein the decorative layer has a sheet resistance of 100 Ω / □ or more.

[14] The laminate according to any one of [1] to

[13] above, wherein the transparent member has a linearly bent portion or a curved portion that is curved in a curved line in any cross section parallel to the stacking direction of the laminate, and the pressure-sensitive adhesive layer and the decorative film are disposed at the bent portion or the curved portion of the transparent member.

[15] Further having one or more colored layers, The laminate described in any one of the above [1] to

[14] , wherein the colored layer is disposed either between the transparent member and the adhesive layer, between the adhesive layer and the decorative film, or on the opposite side of the decorative film to the adhesive layer.

[16] The laminate according to any one of [1] to

[15] above, which is used in a portable electronic device.

[17] The laminate according to any one of the above [1] to

[16] , wherein the pressure-sensitive adhesive layer has a gel fraction of 30 to 95% by weight.

[18] The laminate according to any one of the above [1] to

[17] , wherein the pressure-sensitive adhesive layer has a thickness of 5 to 100 μm.

[0194]

[19] The laminate according to

[11] above, wherein the compound B1 contains at least one structure selected from the group consisting of a bisphenol A structure, a bisphenol F structure, and a bisphenol E structure in the molecule.

[20] The laminate according to

[11] or

[19] above, wherein the compound B1 contains an aliphatic ring structure as the ring structure.

[21] The laminate according to

[11] ,

[19] or

[20] above, wherein the compound B1 contains at least one structure selected from the group consisting of a hydroxyl group and an amino group in the molecule.

[22] The laminate according to any one of

[11] and

[19] to

[21] above, wherein the content of the compound B1 in the pressure-sensitive adhesive layer is 0.5 parts by weight or more and 60 parts by weight or less per 100 parts by weight of the polymer (A).

[23] The laminate according to any one of

[11] and

[19] to

[22] , wherein the pressure-sensitive adhesive layer contains, as the photoreactive monomer (B), the compound B1 and a compound B2 having two or more functional groups and not having a ring structure in the molecule.

[24] The laminate according to

[23] above, wherein the functional group equivalent of the compound B2 is smaller than the functional group equivalent of the compound B1.

[25] The laminate according to

[23] or

[24] above, wherein the compound B2 has a functional group equivalent of 400 g / mol or less.

[26] The laminate according to any one of the above

[23] to

[25] , wherein the content of the compound B2 in the pressure-sensitive adhesive layer is 25 parts by weight or less based on 100 parts by weight of the polymer (A).

[27] The laminate according to any one of

[10] ,

[11] , and

[19] to

[26] , wherein the content of the photoreactive monomer (B) in the pressure-sensitive adhesive layer is 1 part by weight or more and 80 parts by weight or less per 100 parts by weight of the polymer (A).

[28] The laminate according to any one of the above

[10] ,

[11] , and

[19] to

[27] , wherein the polymer (A) is an acrylic polymer.

[29] The laminate according to

[28] above, wherein the monomer component constituting the acrylic polymer includes a monomer having a nitrogen atom-containing ring.

[30] The laminate according to any one of the above

[10] ,

[11] , and

[19] to

[29] , wherein the glass transition temperature of the polymer (A) is −45° C. or higher and lower than 0° C.

[31] The laminate according to any one of the above [1] to

[30] , wherein the pressure-sensitive adhesive layer is crosslinked with a crosslinking agent.

[32] The laminate according to any one of the above [1] to

[31] , wherein the pressure-sensitive adhesive layer contains a photopolymerization initiator.

[33] The laminate according to any one of the above [1] to

[32] , wherein the pressure-sensitive adhesive layer contains a silane coupling agent.

[0195] Some test examples relating to the present invention will be described below, but it is not intended that the present invention be limited to those shown in the test examples. In the following description, "parts" and "%" are based on weight unless otherwise specified.

[0196] <Evaluation method> [Total light transmittance and haze value] One release film is peeled off from the adhesive sheet (adhesive layer) with a release film, and the sheet is attached to a slide glass (manufactured by Matsunami Glass Industry Co., Ltd., product name "White Polishing No. 1", thickness 0.8 to 1.0 mm, total light transmittance 92%, haze value 0.2%). Next, the other release film is peeled off to prepare a test piece having a layer structure of adhesive sheet (adhesive layer) / slide glass. The total light transmittance and haze value of the test piece thus obtained are measured using a haze meter (device name "HM-150N", manufactured by Murakami Color Research Institute). The above measurement is preferably performed by placing the glass plate to which the adhesive sheet (adhesive layer) is attached so that the adhesive sheet (adhesive layer) is on the light source side.

[0197] [Adhesion to glass] The adhesive sheet (adhesive layer) with release film is cut to a length of 100 mm and a width of 20 mm. Next, one release film of the adhesive sheet (adhesive layer) with release film is peeled off, and a PET film (trade name "Lumirror S-10", manufactured by Toray Industries, Inc., thickness 25 μm) is backed up. Next, the release film of the other side (measurement surface side) is peeled off, and a glass plate (trade name "Soda-lime glass #0050", manufactured by Matsunami Glass Industry Co., Ltd.) as a test plate is pressed by rolling a 2 kg roller back and forth once to prepare a test piece consisting of test plate / adhesive sheet (adhesive layer) / PET film. The obtained test piece is autoclaved (50°C, 0.5 MPa, 15 minutes), and then allowed to cool for 30 minutes under an atmosphere of 23°C and 50% RH. After cooling, the adhesive sheet (adhesive layer) (measurement surface side) is peeled off from the test plate using a tensile tester (machine name "Autograph AG-IS", manufactured by Shimadzu Corporation) in accordance with JIS Z 0237 under conditions of 23°C, 50% RH, tensile speed of 300 mm / min, and peel angle of 180°. This is the adhesion strength to glass [N / 20 mm]. In the case of an adhesive sheet protected by a release film with release surfaces on both sides, one adhesive surface is exposed when the adhesive sheet is unwound from a roll, so this surface can be backed with a PET film before carrying out the measurement.

[0198] [Arithmetic mean roughness (Ra) and maximum height (Rz)] The arithmetic mean roughness (Ra) and maximum height (Rz) of the adhesive surface of the adhesive sheet (adhesive layer) are measured as follows: After peeling the release film from the adhesive sheet (adhesive layer) with release film at a peel angle of 180° and a speed of 300 mm / min, the exposed adhesive surface after leaving it to stand for 30 minutes is measured for surface shape using a 3D optical profiler (product name "NewView7300", manufactured by ZYGO Corporation) in an environment of 23°C and 50% RH. The arithmetic surface roughness Ra is calculated from the measured data in accordance with JIS B 0601-2001. The maximum height (Rz) is calculated as the sum of the height Rp of the highest peak above the mean line of the roughness curve and the depth Rv of the deepest valley below the mean line of the data (roughness curve) obtained by the above measurement. The measurement conditions are as follows. The measurements of Ra and Rz are carried out five times (i.e., N=5), and the average values ​​are used. (Measurement conditions) Measurement area: 5.62mm x 4.22mm (Objective lens: 2.5x, internal lens: 0.5x) Analysis mode: Remove: Cylinder Data Fill: ON(Max:25) Remove Spikes: ON (xRMS:1) Filter: OFF

[0199] [Optical distortion evaluation] A commercially available mirror (2 mm thick) made of plain glass by silver coating is prepared, and the mirror is used after visual inspection and projecting a reflected image onto a screen using the same method as described below to confirm that there is no distortion. In a clean room, the surface of the mirror is cleaned with a clean cloth, and then one release film of the adhesive sheet (adhesive layer) with release film is peeled off from the adhesive sheet, and the mirror is attached to the surface of the mirror with an appropriate tension so that no foreign matter, air bubbles, or deformation lines are introduced, and a degassing process is performed using a pressurized degassing device (autoclave) to remove the influence of minute air bubbles (processing conditions: 50°C, 0.5 MPa, 15 minutes). After cooling at room temperature for 30 minutes or more, the other release film is peeled off from the adhesive sheet (adhesive layer) to create an optical distortion evaluation sample (a laminate consisting of an adhesive sheet (adhesive layer) and a mirror). The evaluation sample is placed so that the adhesive sheet (adhesive layer) side faces the point light source side and the angle with respect to the light from the point light source is about 45 degrees. A white screen is placed at the end of the light beam, and the reflected image is projected onto it. As a point light source, a product called "Xenon Lamp C2577" manufactured by Hamamatsu Photonics or an equivalent product can be used. The point light source, evaluation sample, and screen are positioned so that the distance between the evaluation sample and the point light source, and the distance between the evaluation sample and the screen are each approximately 50 cm. The point light source is turned on, and the image reflected by the sample and projected onto the screen is visually observed to evaluate the presence and degree of optical distortion according to the following three levels. E: No optical distortion is observed. A: Some optical distortion is observed, but is within the range of acceptable practical use. P: Obvious optical distortion is observed.

[0200] [Elastic modulus by tensile test] A test specimen was prepared by cutting an adhesive sheet (adhesive layer) with a release film to a size of 10 mm wide and 150 mm long. In an environment of 23°C and 50% RH, two release films were peeled off to expose the adhesive layer. A tensile test was then performed on the test specimen using a tensile testing machine (machine name "Autograph AG-IS", manufactured by Shimadzu Corporation) with a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain an SS curve, and the elastic modulus [MPa] was calculated from the initial slope (the elastic deformation region of the SS curve, specifically the slope in the range where the displacement is less than approximately 5%).

[0201] The thickness of the test piece used in the tensile test may be the same as or different from the thickness of the adhesive sheet (adhesive layer) as described above. For example, when the thickness of the adhesive sheet (adhesive layer) is relatively small, the result obtained by performing the tensile test using a test piece prepared to have a thickness of 5 μm or more (for example, about 5 μm to 200 μm) for the purpose of improving operability, etc., can be adopted as the elastic modulus of the adhesive sheet (adhesive layer). For example, in the case of a photocurable adhesive sheet, the thickness of the test piece can be adjusted by appropriately overlapping the adhesive layer before irradiation with photocurable ultraviolet light. In addition, a test piece having a thickness that is easy to perform a tensile test is prepared using the same adhesive composition as that used to form the adhesive layer to be measured, and the result obtained by performing the tensile test on the test piece can be adopted as the elastic modulus of the adhesive layer. The tensile test can be performed, for example, using a test piece having a thickness of about 10 μm to 50 μm (preferably, about 15 μm to 25 μm).

[0202] [Impact resistance] A shear impact test is performed using a pendulum-type adhesive shear impact tester based on JIS K 6855. As a measurement sample, an adhesive sheet (adhesive layer) with a release film is cut into 10 mm squares, one release film is peeled off to expose a first adhesive surface of the adhesive sheet (adhesive layer), the first adhesive surface is attached to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate (manufactured by Corning), the other release film is peeled off to expose a second adhesive surface of the adhesive sheet (adhesive layer), the second adhesive surface is attached to the center of a 40 mm square stainless steel plate (SUS304BA plate) and pressure-bonded with a load of 5 N for 10 seconds, then autoclaved (50°C, 0.5 MPa, 15 minutes), and an illuminance of 300 mW / cm is applied from the glass plate side using a high-pressure mercury lamp. 2 , Accumulated light intensity 3000mJ / cm 2 After irradiating ultraviolet light under the above conditions, the film is aged at 50°C for 48 hours before use. The measurement sample was fixed so that the stainless steel plate was on the bottom, and the impact resistance [J / 10 mm] was measured by measuring the absorbed energy [J] when a hammer hit the outer peripheral side of the glass plate under conditions of a hammer energy of 2.75 J and a hammer speed (impact speed) of 3.5 m / s in an environment of 23°C and 50% RH. 2 The measurement is carried out three times, and the arithmetic mean value is used. In the case of an adhesive sheet protected by a release film with release surfaces on both sides, one adhesive surface of the adhesive sheet when unwound from a roll is exposed, so a chemically strengthened glass plate is attached to this surface, and the other adhesive surface is peeled off from the release film to expose it, and then attached to a stainless steel plate to obtain a measurement sample, and then the measurement can be performed.

[0203] The pressure-sensitive adhesive sheet (adhesive layer) disclosed herein includes a pressure-sensitive adhesive sheet (adhesive layer) in a form in which the pressure-sensitive adhesive layer is photocured after being attached to an adherend, and therefore, at least the photocurable pressure-sensitive adhesive sheet (for example, the pressure-sensitive adhesive sheet of Example 4 having the pressure-sensitive adhesive C described below) is exposed to an illuminance of 300 mW / cm. 2 , Accumulated light intensity 3000mJ / cm 2The above measurements (total light transmittance, haze value, adhesion to glass, arithmetic mean roughness (Ra) and maximum height (Rz) of the adhesive surface, optical distortion evaluation, elastic modulus by tensile test) are carried out using the measurement sample after aging at 50 ° C for 48 hours. Regarding adhesion to glass, the photocurable adhesive sheet (for example, the adhesive sheet of Example 4 having adhesive C described later) is pressed onto a test plate, and then irradiated with ultraviolet light under the above conditions, and measurement is carried out. In addition, when the release film is transparent, the above ultraviolet irradiation treatment is preferably carried out in a state where the adhesive sheet (typically the adhesive layer) is sandwiched between transparent release films. It is advisable to measure the illuminance and light intensity of the light source using an industrial UV checker (model "UVR-T2", light receiving part "UD-T36T2", manufactured by TOPCON) by adjusting the actual distance between the light source and the sample.

[0204] <Example 1> (Preparation of Pressure-Sensitive Adhesive Composition) After mixing 57 parts of n-butyl acrylate (BA), 12 parts of cyclohexyl acrylate (CHA), 23 parts of 4-hydroxybutyl acrylate (4HBA), 8 parts of hydroxyethyl acrylate (HEA) as monomer components, 0.075 parts of "Irgacure 651" (BASF) and 0.075 parts of "Irgacure 184" (BASF) as photopolymerization initiators, this monomer mixture was exposed to ultraviolet light under a nitrogen atmosphere to partially photopolymerize, thereby obtaining a partially polymerized product (acrylic polymer syrup) with a polymerization rate of about 10%. 0.14 parts of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA", Nippon Kayaku Co., Ltd.) and 0.3 parts of a silane coupling agent (trade name "KBM-403", Shin-Etsu Chemical Co., Ltd.) were added to 100 parts of the obtained acrylic polymer syrup and mixed uniformly to obtain an acrylic adhesive composition A.

[0205] (Preparation of adhesive sheet) As the first release film, a PET release film having a thickness of 75 μm and a first adhesive surface S1, which is the surface to be laminated on the first adhesive surface of the adhesive sheet, being a release surface made of a silicone-based release treatment agent, and surface S1 having an Ra of 18 nm and an Rz of 223 nm, was prepared. As the second release film, a PET release film having a thickness of 100 μm and a second adhesive surface S2, which is the surface to be laminated on the second adhesive surface of the adhesive sheet, being a release surface made of a silicone-based release treatment agent, and surface S2 having an Ra of 18 nm and an Rz of 223 nm, was prepared. The acrylic adhesive composition A obtained above was applied onto the first adhesive surface S1 of the first release film so that the thickness after the adhesive layer was formed would be 100 μm to form an adhesive composition layer, and then the surface of the adhesive composition layer was covered with the second release film so that the second adhesive surface S2 was on the adhesive composition layer side. This blocked the adhesive composition layer from oxygen. Thereafter, the adhesive composition layer was exposed to light at an illuminance of 5 mW / cm 2 , light intensity 2000mJ / cm 2 The pressure-sensitive adhesive composition layer was photocured by irradiating with ultraviolet light under the above conditions to produce a substrate-less double-sided pressure-sensitive adhesive sheet consisting of only an acrylic pressure-sensitive adhesive layer (also referred to as pressure-sensitive adhesive A), each side of which was protected by a first and second release film. The weight-average molecular weight (Mw) of the acrylic polymer serving as the base polymer of the pressure-sensitive adhesive layer was 2,000,000.

[0206] <Example 2> As the first release film, a release film having a first adhesive surface S1 with Ra of 18 nm and Rz of 112 nm was used, and as the second release film, a release film having a second adhesive surface S2 with Ra of 18 nm and Rz of 112 nm was used. In addition, the thickness of the adhesive layer was changed to 25 μm. The substrate-less double-sided adhesive sheet according to this example was produced in the same manner as in Example 1 above.

[0207] <Example 3> An acrylic polymer syrup was prepared in the same manner as in Example 1 above, except that the monomer components were changed to 68 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of N-vinyl-2-pyrrolidone (NVP), and 17 parts of HEA, and an acrylic pressure-sensitive adhesive composition B was obtained in the same manner as in Example 1 above, except that the obtained acrylic pressure-sensitive adhesive composition B was used and the thickness of the pressure-sensitive adhesive layer (also referred to as pressure-sensitive adhesive B) was 50 μm, and a substrate-less double-sided pressure-sensitive adhesive sheet according to this example was produced in the same manner as in Example 2 above.

[0208] <Example 4> (Preparation of Pressure-Sensitive Adhesive Composition) In a reaction vessel equipped with a cooling tube, nitrogen introduction tube, thermometer and stirrer, 60 parts of BA, 6 parts of CHA, 18 parts of NVP, 1 part of isostearyl acrylate (iSTA) and 15 parts of 4HBA as monomer components, 0.085 parts of α-thioglycerol as a chain transfer agent, 0.2 parts of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and ethyl acetate as a polymerization solvent were added so that the monomer components were 45%, and nitrogen gas was flowed and nitrogen replacement was performed for about 1 hour while stirring. After that, the reaction vessel was heated to 60 ° C and reacted for 7 hours to obtain an acrylic polymer with a weight average molecular weight (Mw) of 350,000. To this acrylic polymer solution (100 parts solids), 0.1 parts on a solids basis of trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-110N", solids concentration 75%) as an isocyanate crosslinking agent, 0.01 parts of dioctyltin dilaurate (manufactured by Tokyo Fine Chemicals, product name "Envirizer OL-1") as a crosslinking accelerator, 4 parts of acetylacetone as a crosslinking retarder, 0.3 parts of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") as a silane coupling agent, 8 parts of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DPH") and 12 parts of tricyclodecane dimethanol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-DCP") as photoreactive monomers, and 1-hydroxycyclohexyl-phenyl-ketone (IGM) as a photopolymerization initiator were added. 0.7 parts of "Omnirad184" (manufactured by Regins) was added and mixed uniformly to prepare a pressure-sensitive adhesive composition C according to this example.

[0209] (Preparation of adhesive sheet) As the first release film and the second release film, release films having surfaces S1 and S2 having Ra and Rz shown in Table 1 were used, respectively. The adhesive composition C obtained above was applied onto the first adhesive surface S1 of the first release film so that the thickness after drying was 20 μm, and the adhesive composition C was dried by heating at normal pressure at 60° C. for 1 minute and at 120° C. for 3 minutes, and then aged at 23° C. for 120 hours to form a photocurable adhesive layer (substrate-less double-sided adhesive sheet). The second adhesive surface S2 of the second release film was attached to the surface of this photocurable adhesive layer for protection. In this way, a substrate-less double-sided adhesive sheet was produced, which was composed only of a photocurable acrylic adhesive layer (also referred to as adhesive C) and in which each side of the photocurable acrylic adhesive layer was protected by the first and second release films.

[0210] <Example 5> As the first release film, a release film having a first adhesive surface S1 with Ra of 19 nm and Rz of 256 nm was used, and as the second release film, a release film having a second adhesive surface S2 with Ra of 19 nm and Rz of 196 nm was used. In addition, the thickness of the adhesive layer was changed to 100 μm. The rest of the process was the same as in Example 3 above to produce a substrate-less double-sided adhesive sheet according to this example.

[0211] <Preparation of Laminate> (Creating decorative film) A PET film (125 μm thick, 340 mm wide) manufactured by Mitsubishi Plastics was prepared as the substrate film, and an ITO layer with a thickness of 5 nm was formed directly on the substrate film by DC magnetron sputtering along the surface of the substrate film. The temperature of the substrate film when the ITO layer was formed was set to 130°C. The tin oxide (SnO2) content in the ITO (content = (SnO2 / (In2O3+SnO2)) × 100) was 10%. Next, an aluminum (Al) layer with a thickness of 30 nm was formed on the ITO layer by alternating current sputtering (AC: 40 kHz). The obtained Al layer was a discontinuous layer. The temperature of the substrate film when the Al layer was formed was set to 130°C. An AlO layer with a thickness of 20 nm was formed on the above Al layer by RF (13.6 MHz) power sputtering. xA barrier layer consisting of was formed to obtain a metallic gloss film (decorative film). The temperature of the base film when forming the barrier layer was set to room temperature. The sheet resistance of the Al layer and ITO-containing layer of this decorative film was 3000 Ω / □ or more, and the visible light transmittance was 7% or less.

[0212] (Preparation of Laminate) The first release film of the adhesive sheet (adhesive layer) with release film according to each example was peeled off to expose the first adhesive surface, which was then pressed against a slide glass (manufactured by Matsunami Glass Industry Co., Ltd., product name "White Polish No. 1", thickness 0.8-1.0 mm, total light transmittance 92%, haze value 0.2%) as a transparent member by rolling a 2 kg roller back and forth once. Next, the second release film was peeled off from the adhesive sheet (adhesive layer) to expose the second adhesive surface, and the decorative film obtained above was pressed against the slide glass to produce a laminate in which the transparent member, adhesive layer, and decorative film were arranged in this order. The visible light transmittance of this laminate was 7% or less.

[0213] <Evaluation> The adhesive sheet with release film (adhesive layer) of each example was evaluated for total light transmittance [%], haze value [%], adhesion to glass [N / 20 mm], arithmetic mean roughness (Ra) [nm] of the adhesive surface, maximum height (Rz) [nm], and optical distortion. The results are shown in Table 1. In addition, the adhesive sheet of Example 4 was subjected to measurement of elastic modulus by tensile test, and the adhesive sheets of Examples 1 to 4 were subjected to impact resistance test. Table 1 also shows an overview of each example (adhesive type, adhesive sheet (adhesive layer) thickness [μm], 25°C storage modulus [Pa], gel fraction [%]).

[0214] [Table 1]

[0215] As shown in Table 1, no optical distortion was observed in any of the adhesive layers of Examples 1 to 5, or the optical distortion was within a range acceptable for practical use. These results show that, with a laminate in which the adhesive sheet (adhesive layer) is disposed between a transparent member and a decorative film, the design on the surface of the decorative film can be clearly seen through the transparent member and the adhesive layer. The adhesive sheet (adhesive layer) of Example 4 had a modulus of elasticity of 3.0 MPa or more in a tensile test, and the adhesive sheets (adhesive layers) of Examples 1 to 4 all had an impact resistance of 2.0 J / 10 mm. 2 That was all.

[0216] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above. [Explanation of symbols]

[0217] 1, 2, 3, 4 stack 10 Transparent materials 10a 1st page 10b Second surface (adhesive layer side surface) 20 (1st) Adhesive layer 20a First adhesive surface 20b 2nd adhesive side 30 Decorative Film 30a 1st page 30b 2nd side 40 colored layer 50 colored layer 60 Second adhesive layer 60a First adhesive surface 60b 2nd adhesive side

Claims

1. A laminate in which a transparent member, a pressure-sensitive adhesive layer, and a decorative film are arranged in this order, The decorative film has a base layer and a decoration layer covering at least a part of a surface of the base layer on the side of the pressure-sensitive adhesive layer, and has a decorative surface on the side of the pressure-sensitive adhesive layer, The laminate has a colored layer partially disposed between the transparent member and the pressure-sensitive adhesive layer and between the pressure-sensitive adhesive layer and the decorative film, The pressure-sensitive adhesive layer has a total light transmittance of 85% or more, The transparent member is made of glass, The transparent member has a thickness of 0.5 mm or more, The pressure-sensitive adhesive layer has a thickness of 1 μm to 500 μm.

2. The laminate according to claim 1 , wherein the transparent member, the pressure-sensitive adhesive layer and the decorative film have a visible light transmittance of less than 10% in a lamination direction thereof.

3. The laminate according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has a haze value of 1% or less.

4. The storage modulus of the pressure-sensitive adhesive layer at 25° C. is 4×10 ４ The laminate according to any one of claims 1 to 3, wherein the modulus is 1 Pa or more.

5. The laminate according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer is adhered to the transparent member with a 180 degree peel strength of greater than 7 N / 20 mm.

6. The laminate according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer.

7. The laminate according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer has an elastic modulus of 3.0 MPa or more as measured by the following tensile test. [Tensile test] The pressure-sensitive adhesive layer was exposed to an illuminance of 300 mW / cm ２ , cumulative light amount 3000 mJ / cm ２ After aging at 50° C. for 48 hours, the pressure-sensitive adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test piece. A tensile test is performed on the test piece using a tensile tester under conditions of 23° C., 50% RH, 120 mm between-chuck distance, and 50 mm / min tensile speed to obtain a stress-displacement curve, and the elastic modulus [MPa] is calculated from the initial slope.

8. The pressure-sensitive adhesive layer has an impact resistance of 2.0 J / 10 mm as measured by the following shear impact test. ２ The laminate according to any one of claims 1 to 7. [Shear impact test] A shear impact test is performed using a pendulum-type adhesive shear impact tester based on JIS K6855. As a measurement sample, the first surface of the pressure-sensitive adhesive layer of 10 mm square is attached to the center of a chemically strengthened glass plate of 25 mm square and 1.7 mm thick, and then the second surface of the pressure-sensitive adhesive layer is attached to the center of a stainless steel plate (SUS304BA plate) of 40 mm square, and pressed with a load of 5 N for 10 seconds, and then autoclaved (50°C, 0.5 MPa, 15 minutes), and the illuminance from the glass plate side is 300 mW / cm. ２ , cumulative light amount 3000 mJ / cm ２ After irradiation with ultraviolet light under the above conditions, the film is aged at 50° C. for 48 hours before use. The measurement sample was fixed so that the stainless steel plate was on the lower side, and a hammer was applied to the outer peripheral side surface of the glass plate under conditions of a hammer energy of 2.75 J and a hammer speed of 3.5 m / sec in an environment of 23° C. and 50% RH, and the absorbed energy [J] was measured to determine the impact resistance [J / 10 mm ２ ] is required.

9. The laminate according to any one of claims 1 to 8, wherein the pressure-sensitive adhesive layer contains a polymer (A) and a photoreactive monomer (B).

10. The laminate according to claim 9, wherein the photoreactive monomer (B) includes a compound B1 having a ring structure and two or more ethylenically unsaturated groups in the molecule, and the compound B1 has a molecular weight per one ethylenically unsaturated group of 100 g / mol or more.

11. The laminate according to any one of claims 1 to 10, wherein the decorative layer has a thickness in the range of 1 to 1000 nm.

12. The laminate according to claim 11, wherein the decorative layer has a sheet resistance of 100 Ω / □ or more.

13. The laminate according to any one of claims 1 to 12, wherein the transparent member has a linearly bent portion or a curved portion that is curved in a curved line in any cross section parallel to the stacking direction of the laminate, and the adhesive layer and the decorative film are arranged at the bent portion or the curved portion of the transparent member.

14. The laminate according to any one of claims 1 to 13, further comprising a colored layer disposed on the decorative film on the side opposite to the pressure-sensitive adhesive layer.

15. The laminate according to any one of claims 1 to 14, which is used in a portable electronic device.

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