Laminate

Abstract

To provide a novel laminate that does not impair visibility of a design of a decorative film.SOLUTION: A laminate is provided. A transparent member, an adhesive layer, and a decorative film are disposed in this order in the laminate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminate. More specifically, it relates to a laminate provided with a decorative film.

Background Art

[0002] In various applications such as mobile electronic devices such as smartphones, tablet computers, laptop computers, and cover members of vehicles, decorative films such as metallic films are used for the purpose of imparting design properties and the like. Such a decorative film has a design including colors, color tones, patterns, etc. on its surface (decorative surface). For example, recently, highly functional decorative films having electromagnetic wave permeability in addition to the metallic luster as the above design have been proposed. Patent Document 1 can be cited as a prior art document disclosing this type of prior art.

[0003] By the way, as a bonding means for films and members, adhesives (also referred to as pressure-sensitive adhesives. The same applies hereinafter) are widely used in various industrial fields. An adhesive exhibits a state of a soft solid (viscoelastic body) in a temperature range near room temperature and has a property of easily adhering to an adherend by pressure. Further, in addition to the above adhesiveness, it may have one or more properties suitable for various applications. For example, an adhesive used for optical applications may be excellent in transparency and visibility through the adhesive in addition to the adhesiveness to members. As prior art documents disclosing this type of prior art, for example, Patent Documents 2 and 3 can be cited. Patent Document 4 is a prior art document disclosing an anti-scattering adhesive sheet attached to a cover glass of a capacitive touch panel.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] The conventional use of decorative films described above involves placing the back surface of the decorative film on the surface of the substrate, with the decorative surface (front) of the decorative film typically being placed on the outermost surface. In this configuration, the decorative film needs to have a certain level of durability against external forces and under the usage environment. Alternatively, methods to improve durability by providing a protective layer on the surface of the decorative film can be considered, but this tends to reduce the aesthetic appeal of the decorative film, and the formation of such a protective layer leads to an increase in the number of processes, an increase in thickness, and an increase in cost, making it disadvantageous in terms of productivity.

[0006] This invention was created in view of the above circumstances, and aims to provide a novel laminate that does not impair the visibility of the design of the decorative film. [Means for solving the problem]

[0007] This specification provides a laminate in which a transparent member, an adhesive layer, and a decorative film are arranged in that order. With this laminate, the design on the surface of the decorative film (including colors, tones, patterns, and even textual information such as logos; the same applies hereinafter) can be seen through the transparent member and the adhesive layer. Furthermore, due to the presence of the decorative film, the laminate as a whole can have concealment (internal concealment when the transparent member side is considered 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%. A laminate configured in this way can exhibit good concealment while also showcasing the design of the decorative film. For example, if the transparent member of the laminate is used as the housing of a structure such as a portable electronic device, the interior of the structure is concealed, while the design of the decorative film can be viewed through the transparent member on its outer surface.

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

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

[0011] In some preferred embodiments, the storage modulus of the adhesive layer at 25°C is 4 × 10⁻⁶. 4 The storage modulus at 25°C is Pa or higher. The adhesive layer having the above 25°C storage modulus tends to have desirable heat resistance and easily exhibits good adhesive properties such as deformation resistance.

[0012] In some preferred embodiments, the adhesive layer is bonded to the transparent member with a 180-degree peel strength greater than 7 N / 20 mm. This good adhesion between the transparent member and the adhesive layer allows the laminate to exhibit good durability against impacts and other forces.

[0013] In some preferred embodiments, the adhesive layer is an acrylic adhesive layer. With an acrylic adhesive, the target adhesive properties and viscoelastic properties can be suitably achieved without using additive components such as softeners that may cause a decrease in transparency, or by limiting the amount of additives used, making it easier to achieve both transparency and adhesive / viscoelastic properties. Furthermore, acrylic adhesives tend to have superior discoloration resistance compared to, for example, rubber-based adhesives, which is advantageous in terms of maintaining transparency over a long period of time.

[0014] In some preferred embodiments, the adhesive layer has an elastic modulus of 3.0 MPa or higher, as measured by the tensile test described below. By satisfying the above characteristics, the adhesive layer can exhibit high deformation resistance. [Tensile test] The aforementioned adhesive layer is subjected to an illuminance of 300 mW / cm². 2 , cumulative light intensity 3000 mJ / cm 2 The adhesive layer is irradiated with ultraviolet light under the specified conditions and aged at 50°C for 48 hours. After this, the adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test specimen. In an environment of 23°C and 50% RH, a tensile test is performed on the test specimen using a tensile testing machine with a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain a stress-displacement curve, and the modulus of elasticity [MPa] is calculated from its initial slope.

[0015] In some preferred embodiments, the adhesive layer has an impact resistance of 2.0 J / 10 mm² as measured by the following shear impact test. 2 This concludes the explanation. By satisfying the above characteristics, the adhesive layer can exhibit high impact resistance. For example, an adhesive layer that satisfies the elastic modulus characteristics and impact resistance characteristics determined by the above tensile test can form a joint with high deformation resistance and high impact resistance, and thus a laminate equipped with such an adhesive layer can also have excellent deformation resistance and impact resistance. [Shear impact test] A shear impact test will be performed using a pendulum-type adhesive shear impact tester based on JIS K6855. For the measurement sample, the first surface of the 10 mm square adhesive layer will be bonded to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then the second surface of the adhesive layer will be bonded to the center of a 40 mm square stainless steel plate (SUS304BA plate). The samples will be pressed together with a load of 5 N for 10 seconds, followed by autoclaving (50°C, 0.5 MPa, 15 minutes), and an illuminance of 300 mW / cm² will be applied from the glass plate side. 2 , cumulative light intensity 3000 mJ / cm 2 The product used will have been irradiated with ultraviolet light under these conditions, followed by aging at 50°C for 48 hours. The measurement sample is fixed with the stainless steel plate facing downwards, and the absorbed energy [J] is measured when a hammer is struck against the outer surface of the glass plate under the conditions of hammer energy 2.75J and hammer speed 3.5m / sec in an environment of 23℃ and 50%RH, thereby determining the impact resistance [J / 10mm]. 2 Find the answer to ].

[0016] In some preferred embodiments, the 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 its molecule, and it is more preferable that the molecular weight of compound B1 per ethylenically unsaturated group is 100 g / mol or more. The above adhesive layer can suitably form a bond with high deformation resistance and high impact resistance, so that the laminate comprising the adhesive layer can also have excellent deformation resistance and impact resistance.

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

[0018] In some preferred embodiments, the sheet resistance of the decorative layer is 100 Ω / □ or greater. Since a decorative film having such a decorative layer may be radio wave transparent, it can be preferably used in various applications where radio wave transparency is required, such as portable electronic devices.

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

[0020] Laminates according to some embodiments further have one or more colored layers. The colored layers are located 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 the adhesive layer. With such a laminated structure, higher opacity can be achieved due to the presence of the colored layers.

[0021] Laminates according to several embodiments can be preferably used in portable electronic devices. For example, by using the transparent members 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 allows the design of the decorative film to be visible from the outside, while also having internal concealment, making it particularly suitable as an exterior structure such as a case. Furthermore, by selecting the decorative film, it can have radio wave transparency, making it preferably used as a laminate for portable electronic devices. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic cross-sectional view showing a laminate according to one embodiment. [Figure 2]It is a schematic cross-sectional view showing a laminate according to another embodiment. [Figure 3] It is a schematic cross-sectional view showing a laminate according to another embodiment. [Figure 4] It is a schematic cross-sectional view showing a laminate according to another embodiment.

Mode for Carrying Out the Invention

[0023] Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than those specifically mentioned in this specification and necessary for the implementation of the present invention can be understood by those skilled in the art based on the teachings regarding the implementation of the invention described in this specification and the common technical knowledge at the time of filing. The present invention can be implemented based on the content disclosed in this specification and the common technical knowledge in the relevant field. In the following drawings, members and parts having the same function may be denoted by the same reference numerals for explanation, and duplicate explanations may be omitted or simplified. In addition, the embodiments shown in the drawings are schematized for clearly explaining the present invention, and do not necessarily accurately represent the size and scale of the actually provided product.

[0024] In this specification, the “adhesive” refers to a material that, as described above, exhibits a state of a soft solid (viscoelastic body) in a temperature range near room temperature and has the property of easily adhering to an adherend by pressure. The adhesive here is, as defined in “C. A. Dahlquist, ‘Adhesion: Fundamental and Practice’, McLaren & Sons, (1966) P. 143”, generally a material having a property that satisfies the complex tensile elastic modulus E * (1Hz) < 10 7 dyne / cm 2 and can be a material having the above properties (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 acrylic monomers, and is also called an acrylic polymer. The above-mentioned acrylic monomer refers to a monomer having at least one (meth)acryloyl group in one molecule. In this specification, "(meth)acryloyl" comprehensively refers to acryloyl and methacryloyl. Similarly, "(meth)acrylate" comprehensively refers to acrylate and methacrylate, and "(meth)acrylic" comprehensively refers to acrylic and methacrylic. In this specification, "mass" and "weight" shall be considered synonymous.

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

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

[0028] Figure 2 schematically shows the structure of a laminate according to another embodiment. Laminate 2 shown in Figure 2 differs from laminate 1 shown in Figure 1 in that a colored layer 40 is placed 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 amount of its thickness, 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 this step-forming surface. Note that other points are basically the same as the configuration shown in Figure 1, so redundant explanations are omitted here.

[0029] Furthermore, Figure 3 schematically shows the structure of a laminate according to another embodiment. The laminate 3 shown in Figure 3 differs from the laminate 2 shown in Figure 2 in that it has a colored layer 50 below the decorative film 30 (on the opposite side from the adhesive layer 20). That is, the laminate 3 is a laminate in which the transparent member 10, the adhesive layer 20, the decorative film 30, and the colored layer 50 are arranged in this order. Also, similar to the laminate 2, the laminate 3 has a colored layer (a partially arranged colored layer) 40 arranged between the transparent member 10 and the adhesive layer 20. In this embodiment, the colored layer 50 is arranged on the second surface 30b of the decorative film 30 (the opposite surface from the first surface 30a on the adhesive layer 20 side). More specifically, the colored layer 50 is arranged over 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 opacity in the direction of its lamination. Furthermore, since the other aspects are basically the same as the configuration shown in Figure 2, we will omit any redundant explanations here.

[0030] Furthermore, Figure 4 schematically shows the structure of a laminate according to another embodiment. The laminate 4 shown in Figure 4 differs from the laminate 3 shown in Figure 3 in that it has a second adhesive layer 60 below the decorative film 30 (on the opposite side from the first adhesive layer 20), and a colored layer 50 below the second adhesive layer 60 (on the opposite side from the decorative film 30). 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. Also, similar to the laminate 3, the laminate 4 has a colored layer (a partially arranged colored layer) 40 arranged between the transparent member 10 and the adhesive layer 20. 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 adhesive layer 60 and the colored layer 50 may be single-sided adhesive sheets with a colored substrate. Furthermore, the thickness of the second adhesive layer 60 is greater than the thickness of the first adhesive layer 20. The colored layer 50 is arranged across the entire second surface 60b of the second adhesive layer 60, similar to the configuration shown in Figure 3. In this embodiment, the colored layer 50 is a black layer, and the laminate 4 has opacity in the lamination direction. Note that other aspects are basically the same as the configuration shown in Figure 3, so redundant explanations are omitted here.

[0031] In the configurations shown in Figures 2-4, the colored layer 40 was partially provided on the second surface 10b of the transparent member 10, but the design is not limited to this. The partially provided colored layer may also be provided in a recess formed on the second surface of the transparent member. This prevents the partially provided colored layer from protruding from the second surface. Alternatively, the partially provided colored layer may be partially formed on the first adhesive surface of the adhesive layer. It is also possible to provide such a colored layer on the second surface of the adhesive layer.

[0032] Furthermore, in the configurations shown in Figures 3-4, the colored layer 50 was positioned below the decorative film (on the opposite side from the adhesive layer 20). However, such a colored layer may also be positioned between the decorative film 30 and the second adhesive layer 60 in the laminate 4 shown in Figure 4. Alternatively, the colored layer may be positioned as a colored adhesive layer below the decorative film (on the opposite side from the adhesive layer 20).

[0033] Furthermore, additional layers such as an undercoat layer or an easy-adhesion layer may be present between the transparent member and the adhesive layer, and between the adhesive layer and the decorative film. Any layer, such as a layer containing a coloring agent, may be provided on at least a part (the entire surface or partially) of the surface within a transparent range. A protective layer, such as a hard coat layer, may be provided on the side of the transparent member opposite to the adhesive layer (outside).

[0034] Furthermore, the adhesive layer may be a substrate-embedded adhesive layer in which a non-peelable substrate is embedded (recessed). The substrate can be a plastic film, paper, nonwoven fabric, etc. In addition, Figures 1-4 illustrate a configuration in which the (first) adhesive layer 20 and the second adhesive layer 60 are single-layer structures, but the configuration of the adhesive layer is not limited to this. For example, the adhesive layer may be composed of two or more sub-adhesive layers made of the same or different adhesives. From the viewpoint of productivity and transparency, a single-layer adhesive layer is preferred.

[0035] <Characteristics of laminated materials> The laminate disclosed herein preferably has a visible light transmittance of less than 30% in the lamination direction of the transparent member, adhesive layer, and decorative film. A laminate configured in this manner can exhibit the design appeal of the decorative film while also having good concealment properties. For example, if the transparent member of the laminate is used as the housing of a structure such as a portable electronic device, the interior of the structure will be concealed, while the design of the decorative film will be visible through the transparent member and adhesive layer on its outer surface.

[0036] 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, and even 1.0% or less (substantially 0-1.0%), from the viewpoint of opacity and light shielding. The visible light transmittance of the laminate can be adjusted by setting the transmittance of the decorative film, the arrangement and thickness of one or more colored layers, the selection and concentration of colorants in the colored layers, etc. The visible light transmittance of the laminate is determined by measuring the transmittance in the visible light region (380-780 nm) with a spectrophotometer. The same method is used in the examples described later.

[0037] <Transparent material> The transparent members disclosed herein are not particularly limited in their transparency, as long as they are transparent. The materials constituting the transparent members may include, for example, glass such as alkali glass or alkali-free glass; resin materials such as acrylic resin, ABS resin, polycarbonate resin, transparent polyimide, polyester resin such as polyethylene terephthalate (PET), and polystyrene resin; and so on. The transparent member materials can be used individually or in combination by laminating two or more types.

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

[0039] (Haze value) In some embodiments, the haze value of the transparent member is, for example, approximately 10% or less, and preferably approximately 3% or less. From the viewpoint of visibility through the transparent member, in some preferred embodiments, the haze value of the transparent member is approximately 1% or less, more preferably approximately 0.8% or less, and even more preferably 0.5% or less. The lower limit of the above haze value is theoretically 0%, and in practice, it may be approximately greater than 0.0%. Note that "haze value" refers to the ratio of diffusely transmitted light to total transmitted light when visible light is irradiated onto the object to be measured. 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 transparent materials can be measured using a haze meter. A haze meter such as the "HM-150N" manufactured by Murakami Color Technology Laboratory, or an equivalent model, can be used.

[0041] Transparent members having the total light transmittance and haze value described above may be colored or colorless transparent members. In this specification, "transparent" is used to include the concept of translucency.

[0042] The transparent member described above may be a flat plate, but may also have irregularities such as printing or engraving on the surface to which the adhesive layer is attached, or the transparent member as a whole may have a three-dimensional shape. The adhesive layer disclosed herein may have excellent step-following properties, and can therefore adhere well to the surface of the transparent member having the irregularities. Furthermore, the transparent member having a three-dimensional shape may have a bent portion that bends in a straight line or a curved portion that curves in a curved shape in its cross-section in the thickness direction. The transparent member may have a shape on the adhesive layer side that is bent or curved in any one direction, or it may have a shape that is bent or curved in two directions, in addition to the one direction mentioned above, in a direction that intersects (for example, perpendicular to) that one direction. In other words, the adhesive layer side of the transparent member may have a two-dimensional or three-dimensional structure.

[0043] In embodiments including a transparent member having a two-dimensional or three-dimensional structure as described above, the adhesive layer and decorative film laminated on the transparent member, and additional layers such as a colored layer if necessary, may be arranged only on the flat portion of the transparent member, or they may be arranged not only on the flat portion but also on the three-dimensional shaped portion of the transparent member (specifically, the bent portion or curved portion). With this configuration, the design on the surface of the decorative film can be seen through the transparent member and adhesive layer even in the three-dimensional shaped portion of the transparent member, and the laminate may also have shielding properties in the three-dimensional shaped portion of the transparent member.

[0044] The thickness of the transparent material is set appropriately according to the purpose and manner of use, and is not limited to a specific range. For example, the thickness of the transparent material is 0.01 mm or more, 0.05 mm or more is appropriate, and from the viewpoint of strength, it is preferably 0.1 mm or more, it may be 0.5 mm or more, it may be 1 mm or more, or it may be 3 mm or more. Also, the thickness of the transparent material is approximately 30 mm or less is appropriate, preferably approximately 10 mm or less, it may be approximately 7 mm or less, it may be approximately 5 mm or less, it may be approximately 2 mm or less, or it 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 composed of one or more adhesives selected from various known adhesives such as acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, mixtures thereof, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. Here, acrylic adhesive refers to an adhesive whose base polymer is an acrylic polymer (the main component of the polymer component, i.e., a component included in more than 50% by weight). The same meaning applies to rubber adhesives and other adhesives.

[0046] (Polymer (A)) In some embodiments, the adhesive layer contains polymer (A). Examples of materials that can be used as 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 fluoropolymers, which are known in the field of adhesives. These can be used individually or in combination of two or more.

[0047] The weight percentage of polymer (A) in the total weight of the adhesive layer is appropriately 40% by weight or more, 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 approximately 80% by weight or more, approximately 90% by weight or more, and may be approximately 97% by weight or more (for example, approximately 99% by weight or more). Adhesives with a high polymer (A) content tend to have excellent transparency. In addition, the weight percentage of polymer (A) in 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, and may be 87% by weight or less.

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

[0049] In some embodiments, (meth)acrylic acid C is included in the entire monomer component of the acrylic polymer (A). 1-20The proportion of alkyl esters is appropriately greater than 40% by weight, as it allows for a good balance of properties. For example, it may be 45% by weight or more, 50% by weight or more, 55% by weight or more, or 60% by weight or more. Among the monomer components, (meth)acrylic acid C 1-20 The proportion of alkyl ester can be 100% by weight, but it is appropriate to have 98% by weight or less to easily balance the properties, for example it may be 95% by weight or less, or even 90% by weight or less. In some embodiments, C is included in the total monomer component of the acrylic polymer (A). 1-20 The proportion of alkyl methacrylate 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, from the viewpoint of improving the cohesiveness of the adhesive layer.

[0050] (meth)acrylic acid C 1-20 Non-specific 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 (meth)acrylate, and i Examples include sooctyl, 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] Of 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 is (meth)acrylic acid C 4-18 Examples of alkyl esters include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). (meth)acrylate C is a preferred choice. 4-20 Other specific examples of alkyl esters include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), and isostearyl acrylate (iSTA). These (meth)acrylate C 4-20 Alkyl esters can be used individually or in combination of two or more types.

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

[0053] In some embodiments, the monomer component constituting the acrylic polymer (A) is (meth)acrylic acid C 4-18 It may contain alkyl esters in a proportion of 40% by weight or more. (meth)acrylate C in the monomer component. 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. Furthermore, from the viewpoint of improving the cohesiveness of the adhesive layer, (meth)acrylic acid C is included in the monomer component. 4-18The proportion of alkyl esters should be 99.5% by weight or less, but may also be 95% by weight or less, 85% by weight or less, or 75% by weight or less.

[0054] The monomer components constituting the acrylic polymer (A) may, optionally, include other monomers copolymerizable with the (meth)acrylate alkyl ester (copolymerizable monomers). Suitable copolymerizable monomers include monomers having polar groups (e.g., carboxyl groups, hydroxyl groups, nitrogen-containing rings, etc.) and monomers with relatively high glass transition temperatures (e.g., 10°C or higher) of the homopolymer. Monomers having polar groups can be useful for introducing crosslinking points into the acrylic polymer (A) or for increasing the cohesive strength of the adhesive. Copolymerizable monomers can be used individually or in combination of two or more.

[0055] Non-specific 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, etc. Monomers containing acid anhydride groups: For example, maleic anhydride, itaconic anhydride. Hydroxypropyl monomers: For example, 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, hydroxyalkyl (meth)acrylate such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, etc. Monomers containing sulfonic acid groups or phosphate groups: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethylacryloyl 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, glycidyl (meth)acrylate, etc. Cyano group-containing monomers: for example, acrylonitrile, methacrylonitrile, etc. Monomers containing isocyanate groups: for example, 2-isocyanate ethyl (meth)acrylate, etc. 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, 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, 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)acrylamides such as N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide; and others such as N,N-dimethylaminopropyl(meth)acrylamide and N-(meth)acryloylmorpholine. Amino group-containing monomers: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate. Monomers containing epoxy groups: for example, glycidyl (meth)acrylate, methylglycidyl (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-morpholindione, 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)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyhexamethylenesuccinimide, etc. Maleimides: For example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc. Itaconimides: For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, etc. (meth)acrylate aminoalkyls: for example, (meth)acrylate aminoethyl, (meth)acrylate N,N-dimethylaminoethyl, (meth)acrylate N,N-diethylaminoethyl, (meth)acrylate t-butylaminoethyl. Alkoxy group-containing monomers: For example, alkoxyalkyl (alkoxyalkyl (meth)acrylate) types 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 glycol (e.g., alkoxypolyalkylene glycol (meth)acrylate) types 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, as well as alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane. 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 alicyclic hydrocarbon groups: For example, alicyclic hydrocarbon group-containing (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and adamantyl (meth)acrylate. (Meth)acrylic acid esters having aromatic hydrocarbon groups: for example, aromatic hydrocarbon group-containing (meth)acrylates such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate. Other examples include heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen-containing (meth)acrylates such as vinyl chloride and fluorine-containing (meth)acrylates, silicon-containing (meth)acrylates such as silicone (meth)acrylate, and (meth)acrylic acid esters obtained from terpene compound derivative alcohols.

[0056] When using such copolymerizable monomers, the amount used is not particularly limited, but it is appropriate to use at least 0.01% by weight of the total monomer components. From the viewpoint of better demonstrating the effects of using copolymerizable monomers, the amount of copolymerizable monomer used may be 0.1% by weight or more of the total monomer components, or 0.5% by weight or more. Furthermore, from the viewpoint of easily balancing the adhesive properties, it is appropriate to use at least 50% by weight of the total monomer components, and preferably at least 40% by weight.

[0057] In some embodiments, the monomer components constituting the acrylic polymer (A) may include monomers having nitrogen atoms. The use of monomers having nitrogen atoms can enhance the cohesive force of the adhesive and preferably improve the peel strength after photocuring. A suitable example of a monomer having nitrogen atoms is a monomer having a nitrogen atom-containing ring. Examples of monomers having a nitrogen atom-containing ring include those exemplified above, for example, general formula (1): [ka] An N-vinyl cyclic amide represented by can be used. Here, in general formula (1), R 1 It is a divalent organic group, specifically -(CH2) n - is an integer between 2 and 7 (preferably 2, 3, or 4). Among these, N-vinyl-2-pyrrolidone can be preferably used. Another preferred example of a monomer having a nitrogen atom is (meth)acrylamide.

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

[0059] In some embodiments, the monomer components constituting the acrylic polymer (A) may include hydroxyl group-containing monomers. The use of hydroxyl group-containing monomers can suitably adjust the cohesive force and degree of crosslinking (e.g., crosslinking with isocyanate crosslinking agents) of the adhesive. The amount of hydroxyl group-containing monomer used is not particularly limited, and may be, for example, 0.01% by weight or more of the total monomer component, 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. Furthermore, from the viewpoint of suppressing the water absorption of the adhesive layer, in some embodiments, the amount of hydroxyl group-containing monomer used may be, for example, 40% by weight or less of the total monomer component, for example, 30% by weight or less, 25% by weight or less, or 20% by weight or less. In some other embodiments, the amount of hydroxyl group-containing monomer used may be, for example, 15% by weight or less of the total monomer component, for example, 10% by weight or less, or 5% by weight or less.

[0060] In some embodiments, the proportion of carboxyl group-containing monomers in the monomer component 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 carboxyl group-containing monomers as a monomer component. Here, substantially not using carboxyl group-containing monomers means not using them at least intentionally. An adhesive layer containing an acrylic polymer (A) in which the amount of carboxyl group-containing monomers used is limited as described above is preferred from the viewpoint of preventing metal corrosion. Such an adhesive layer can also be preferably used in a manner that contacts an adherend having a metal material, for example.

[0061] In some embodiments, the monomer components constituting the acrylic polymer (A) may include alicyclic hydrocarbon group-containing (meth)acrylate. This can enhance the cohesive force of the adhesive and improve the peel strength after photocuring. Examples of alicyclic hydrocarbon group-containing (meth)acrylates that can be used include those exemplified above, and for example, cyclohexyl acrylate and isobornyl acrylate are preferably used. When using alicyclic hydrocarbon group-containing (meth)acrylate, the amount used is not particularly limited and can be, for example, 1% or more by weight, 3% or more by weight, or 5% or more by weight of the total monomer components. In some embodiments, the amount of alicyclic hydrocarbon group-containing (meth)acrylate used may be 10% or more by weight of the total monomer components, or 15% or more by weight. The upper limit of the amount of alicyclic hydrocarbon group-containing (meth)acrylate used is appropriately about 40% or less by weight, for example, it may be 30% or less by weight, or 25% or less by weight (for example, 15% or less by weight, and even 10% or less by weight).

[0062] The polymerization method used to form (synthesize) polymer (A) from monomer components is not particularly limited, and various conventionally known polymerization methods can be appropriately employed. For example, polymerization methods such as thermal polymerization (typically carried out in the presence of a thermal polymerization initiator), including solution polymerization, emulsion polymerization, and bulk polymerization; photopolymerization (typically carried out in the presence of a photopolymerization initiator), which is performed by irradiation with light such as ultraviolet light; and radiation polymerization (typically carried out by irradiation with radiation such as beta rays and gamma rays) can be appropriately employed. Two or more polymerization methods may also be combined (for example, in steps).

[0063] For solution polymerization, one solvent or a mixture of two or more solvents can be used as the solvent (polymerization solvent), for example, 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 (e.g., monohydric alcohols with 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; etc.

[0064] In polymerization, known or conventional thermal polymerization initiators or photopolymerization initiators may be used depending on the polymerization method and polymerization mode. Such polymerization initiators can be used individually or in appropriate combinations of two or more.

[0065] While not particularly limited, the following can be used as thermal polymerization initiators: azo polymerization initiators, peroxide initiators, redox initiators using a combination of peroxide and reducing agent, substituted ethane initiators, etc. More specifically, for example, 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 azo initiators include 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; and redox initiators such as combinations of persulfates and sodium bisulfite, or peroxides and sodium ascorbate; but are not limited to these. Thermal polymerization can preferably be carried out at a temperature of, for example, 20 to 100°C (typically 40 to 80°C), but is not limited to this.

[0066] While not particularly limited, the following can be used as photopolymerization initiators: 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, thioxanthone-based photopolymerization initiators, and the like.

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

[0068] For the above polymerization, various conventionally known chain transfer agents (which may also be known as molecular weight modifiers or degree of polymerization modifiers) can be used as needed. As chain transfer agents, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α-thioglycerol can be used. Alternatively, chain transfer agents that do not contain sulfur atoms (non-sulfur chain transfer agents) 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 benzylidenyl 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; and benzyl hydrogens such as diphenylbenzene and triphenylbenzene. Chain transfer agents can be used individually or in combination of two or more. The technology disclosed herein can also be preferably implemented in a form that does not use chain transfer agents.

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

[0070] In the technologies disclosed herein, the glass transition temperature (Tg) of polymer (A) is not particularly limited, but is suitable to be 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 polymer (A) decreases. In some embodiments, the Tg of polymer (A) may be less than -25°C or less than -30°C. Also, the Tg of polymer (A) is typically -80°C or higher, for example, may be -70°C or higher, may be -60°C or higher, or may be -55°C or higher. From the viewpoint of increasing the elastic modulus, in some embodiments, the Tg of polymer (A) is preferably -50°C or higher, more preferably -45°C or higher, may be -40°C or higher, may be -38°C or higher, or may be -35°C or higher.

[0071] Herein, in this specification, the Tg of a polymer refers to the Tg determined by Fox's formula based on the composition of the monomer components used in the preparation of the polymer. Fox's formula, as shown below, is a relationship 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. 1 / Tg = Σ(Wi / Tgi)

[0072] In Fox's equation above, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the monomer i homopolymer (unit: K). If the polymer for which Tg is to be 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 in calculating Tg shall be the value specified in publicly available documents. For example, for the monomers listed below, the following values ​​shall be used as the glass transition temperature of the homopolymer of the monomer. 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 monomer homopolymers other than those exemplified above, the values ​​listed in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. If multiple values ​​are listed in this document, the highest value shall be adopted.

[0075] The weight-average molecular weight (Mw) of 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 polymer (A) is, for example, approximately 10 × 10 4 The above is appropriate, 20 × 10 4 It is preferable that it be greater than 30 × 10 4 Super is fine, 40 x 10 4 Super is fine, 50 x 10 4 It can also be "super". Also, the upper limit of Mw for polymer (A) is approximately 500 × 10 4 The following is possible. In some embodiments, from the viewpoint of adhesion to the adherend and peel strength, the Mw of polymer (A) is, for example, 300 × 10 4 The following may be used: 150 × 10 4 The following is also acceptable: 100 x 10 4 The following is also acceptable: 90 x 10 4 The following is also acceptable: 75 x 10 4 The following is also acceptable. The above examples of Mw may apply to the Mw of polymer (A) in the adhesive layer disclosed herein, or to the Mw of polymer (A) in the adhesive composition used to form the adhesive layer.

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

[0077] (Photoreactive monomer (B)) In some preferred embodiments, the adhesive layer may include a photoreactive monomer (B) in addition to the polymer (A) described above (e.g., acrylic polymer (A)). As the photoreactive monomer (B), a compound having two or more ethylenically unsaturated groups (hereinafter also referred to as "number of functional groups") in the molecule can be used. There is no particular upper limit to the number of functional groups of the compound used as the photoreactive monomer (B). The number of functional groups 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, for example, 2 to 10 ethylenically unsaturated groups can be used, preferably a compound with 2 to 8 functional groups, and more preferably a compound with 2 to 6 functional groups. The photoreactive monomer (B) can be used alone or in combination of two or more.

[0078] The photoreactive monomer (B) contained in the adhesive layer can form a crosslinked structure by reacting with the ethylenically unsaturated groups after application to the substrate by irradiation with light (e.g., ultraviolet light). The deformation resistance of the adhesive layer containing the photoreactive monomer (B) can be improved by curing the adhesive layer by irradiation with ultraviolet light after application to the substrate. This allows for a favorable balance between good conformability to the surface shape of the substrate during application and high deformation resistance after application.

[0079] The above examples of ethylenically unsaturated groups include, but are not limited to, acryloyl, methacryloyl, vinyl, and allyl groups. The two or more ethylenically unsaturated groups in the photoreactive monomer (B) may be the same group or two or more different groups. From the viewpoint of photoreactivity, preferred ethylenically unsaturated groups include acryloyl and methacryloyl groups. Among these, acryloyl groups are preferred.

[0080] The functional group equivalent of the compound used as the photoreactive monomer (B) is not particularly limited. The above 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) can be preferably used as the photoreactive monomer (B).

[0081] The functional group equivalent of photoreactive monomer (B) is calculated by dividing the molecular weight [g / mol] of photoreactive monomer (B) by the number of ethylene unsaturated functional groups it possesses. The molecular weight of photoreactive monomer (B) can be obtained, for example, by the GPC method as the weight-average molecular weight on a standard polystyrene basis. Alternatively, the molecular weight [g / mol] of photoreactive monomer (B) may be the manufacturer's stated value or the molecular weight calculated from the molecular structure.

[0082] The molecular weight of the photoreactive monomer (B) is not particularly limited and can be selected so as to suitably exhibit the desired effect. For example, a photoreactive monomer (B) with a molecular weight of approximately 20,000 or less can be used. From the viewpoint of ease of preparation and coating properties of the 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, and typically 120 or more. From the viewpoint of processability and handling properties, 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 photoreactive monomer (B) contained in the adhesive layer is not particularly limited and can be appropriately set according to the target performance (e.g., the elastic modulus of the adhesive layer after photocuring). In some embodiments in which the adhesive layer contains polymer (A) and photoreactive monomer (B), the amount of photoreactive monomer (B) per 100 parts by weight of polymer (A) contained in the adhesive layer may be, for example, 1 part by weight or more, and preferably 3 parts by weight or more. From the viewpoint of making it easier to increase the elastic modulus of the adhesive layer after photocuring, the amount of photoreactive monomer (B) per 100 parts by weight of 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. Furthermore, from the viewpoint of cohesiveness and handling (e.g., processability) of the adhesive layer before photocuring, the amount of photoreactive monomer (B) per 100 parts by weight of polymer (A) is appropriate to be 80 parts by weight or less, preferably 60 parts by weight or less, and may also 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 adhesive layer preferably contains at least a compound B1 as the photoreactive monomer (B), which has a ring structure and two or more ethylenically unsaturated groups in its molecule. An adhesive layer containing a compound B1 with such a structure can effectively increase the deformation resistance of the adhesive layer upon light irradiation. The ring in the ring structure may be an aliphatic ring or an aromatic ring. The ring may also be a carbon ring or a heterocycle. The number of rings contained in one molecule of compound B1 may be one or two or more. There is no particular upper limit to the number of rings contained in compound B1; for example, it may be 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. If compound B1 contains two or more rings, these rings may or may not form a fused ring (typically a bicyclic or tricyclic fused ring). The above-mentioned 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 above-mentioned ring structure. Compound B1 can be used alone or in combination of two or more types.

[0085] As compound B1, a compound having a ring structure and two or more ethylenically unsaturated groups within the molecule, and having a functional group equivalent of 100 g / mol or more, can preferably be used. When compound B1 satisfying the above functional group equivalent is used as an adhesive layer, a bond with high deformation resistance and high impact resistance can be suitably formed. The reason for obtaining such effects is not to be interpreted in a particularly restrictive way, but it is thought 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 being above a predetermined level maintains the distance between crosslinking points, thereby forming a crosslinked structure with 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. Impact resistance tends to improve with increasing functional group equivalent of compound B1. The functional group equivalent of compound B1 may be, for example, 10,000 g / mol or less, 8,000 g / mol or less, 5,000 g / mol or less, 3,000 g / mol or less, or 2,000 g / mol or less. In some embodiments, from the viewpoint of photocurability, etc., the functional group equivalent of compound B1 is preferably 800 g / mol or less, and more preferably 600 g / mol or less. In some embodiments, the functional group equivalent of compound B1 may be 500 g / mol or less, 400 g / mol or less, or 300 g / mol or less.

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

[0087] Compound B1 may have functional groups other than ethylenically unsaturated groups. Examples of functional groups other than ethylenically unsaturated groups include hydroxyl groups, carboxyl groups, and amino groups. Preferred examples of functional groups other than ethylenically unsaturated groups include hydroxyl groups and amino groups.

[0088] Examples of compound B1 include bisphenol A type epoxy (meth)acrylates such as bisphenol A glycidyl ether (meth)acrylic acid adduct, bisphenol A glycidylamine (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 glycidylamine (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, and bisphenol E Bisphenol E type epoxy (meth)acrylates such as glycidylamine (meth)acrylate adducts and bisphenol E glycidyl ester (meth)acrylate adducts; 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)full orange (meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]full orange (meth)acrylate (Meth)acrylates containing a fluorene skeleton, such as rilate; 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 phthalate type epoxy(meth)acrylate, hydrogenated terpenephenol(meth)acrylate, 1,4-cyclohexanedimethanol diglycidyl ether(meth)acrylate, etc., which may be aliphatic rings (or alicyclic condensed rings).Examples of (meth)acrylates having ); (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 terpenephenol 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 versions of any of the above materials (e.g., amine-modified, acid-modified, halogen-modified); etc., but not limited to these. In some embodiments, compound B1 having an aromatic carbon ring can be preferably used. Preferred examples of 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 their modified products (e.g., amine-modified products).

[0089] Commercially available products that can be used as compound B1 include, but are not limited to, the following: "A-DCP" and "A-BPE-4" from Shin-Nakamura Chemical Industry Co., Ltd., "Viscote #540" and "Viscote #700HV" from Osaka Organic Chemical Industry Co., Ltd., "R-114F" from Nippon Kayaku Co., Ltd., "Epoxy Ester 3000A" and "Epoxy Ester 80MFA" from Kyoeisha Chemical Co., Ltd., and "EBECRYL 3700," "EBECRYL 3703," and "EBECRYL 3603" from Daicel Ornex Co., Ltd.

[0090] The amount of compound B1 per 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 making it easier to obtain an adhesive layer that balances deformation resistance and impact resistance well, in some embodiments, the amount of compound B1 per 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. Furthermore, from the viewpoint of cohesiveness and handling of the adhesive layer before photocuring, the amount of compound B1 per 100 parts by weight of polymer (A) is appropriate to be 80 parts by weight or less, preferably 60 parts by weight or less, may be 50 parts by weight or less, may be 40 parts by weight or less, may be 35 parts by weight or less, may be 25 parts by weight or less, or may be 15 parts by weight or less.

[0091] In some embodiments, the adhesive layer may contain, as the photoreactive monomer (B), compound B2 having two or more functional groups and no ring structure within the molecule. Compound B2 is preferably used in combination with compound B1. This adjusts the crosslinking structure of the adhesive layer, making it possible to form a bond that more favorably balances deformation resistance and impact resistance. Compound B2 can be used alone or in combination of two or more types.

[0092] The number of functional groups in compound B2 may be, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 15 or less. In some embodiments, the number of functional groups in compound B2 may be, for example, 2 to 10, preferably 3 to 10, 3 to 8, or 4 to 6. For example, in embodiments where compound B1 is a compound with 2 functional groups, it may be advantageous to use compound B2 with 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 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 compound B2 may be, for example, 600 g / mol or less, and 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 from the viewpoint of improving photocurability and the hardness of the cured product. The functional group equivalent of compound B2 is typically 50 g / mol or more, preferably 60 g / mol or more, may be 70 g / mol or more, may be 80 g / mol or more, or may be 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, hydroxypivalate neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, EO-modified or PO-modified versions of any of the above materials, etc.

[0095] In embodiments using compound B2, the amount of compound B2 per 100 parts by weight of 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 making it easier to obtain an adhesive layer that balances deformation resistance and impact resistance well, in some embodiments, the amount of compound B2 per 100 parts by weight of 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. Furthermore, from the viewpoint of suppressing a decrease in adhesion to the adherend due to excessive crosslinking, in some embodiments, the amount of compound B2 per 100 parts by weight of polymer (A) is, for example, suitable 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 embodiments where compound B1 and compound B2 are used in combination, compound B2 may preferably be a compound having 3 or more functional groups and having a smaller functional group equivalent than compound B1 used in combination with it. In some embodiments, the ratio of the functional group equivalent FE2 of compound B2 to the functional group equivalent FE1 of compound B1 (FE2 / FE1) may be, for example, 0.9 or less, 0.7 or less, 0.5 or less, or 0.4 or less. According to such embodiments, the effect of improving the elastic modulus by the photoreactive monomer (B) can be efficiently exerted. The lower limit of the above 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 embodiments where compound B1 and compound B2 are used in combination, the weight ratio (W2 / W1) of the amount of compound B2 used W2 to the amount of compound B1 used W1 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 effects of using compound B1 and compound B2 in combination tend to be favorably exhibited.

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

[0099] In some embodiments, the photoreactive monomer (B) may be included in the adhesive layer in a free form. Such an adhesive layer can be suitably formed using an adhesive composition containing the photoreactive monomer (B) in a free form. Here, "free form" means that the photoreactive monomer (B) is not chemically bonded to other components (e.g., polymer (A)) contained in the adhesive layer or adhesive composition. Adhesive compositions containing the photoreactive monomer (B) in a free form may be advantageous in terms of ease of preparation and suppression of gelation.

[0100] In several other forms, at least a portion of the photoreactive monomer (B) may be included in the adhesive layer in a form chemically bonded to other components (e.g., polymer (A), crosslinking agent described later) in the adhesive layer or adhesive composition, from the viewpoint of improving processability, etc. The above chemical bond may be, for example, a bond formed by the reaction of a functional group F1 other than an ethylenically unsaturated group that the photoreactive monomer (B) has in its molecule and a functional group F2 that has in the molecule of the other component and is capable of reacting with the functional group F1. The above other component may be a crosslinking agent, and the photoreactive monomer (B) may be bonded to polymer (A) via the crosslinking agent.

[0101] (Acrylic oligomers) The adhesive layer disclosed herein may contain an acrylic oligomer for the viewpoint of improving cohesive strength and adhesion to adjacent surfaces (e.g., transparent members or decorative films). The adhesive layer containing the acrylic oligomer can preferably be formed using an adhesive composition containing the acrylic oligomer. As the acrylic oligomer, one having a higher Tg than the polymer (A) described above can preferably be used.

[0102] The Tg of the above acrylic oligomer is not particularly limited and may be, for example, between approximately 20°C and 300°C. The above Tg may be, for example, above approximately 30°C, above approximately 40°C, above approximately 60°C, above approximately 80°C, or above approximately 100°C. Generally, as the Tg of the acrylic oligomer increases, the effect of improving cohesive force tends to increase. Furthermore, from the viewpoint of adhesion to the adherend and shock absorption, the Tg of the acrylic oligomer may be, for example, below approximately 250°C, below approximately 200°C, below approximately 180°C, or below approximately 150°C. Note that the Tg of the acrylic oligomer is a value calculated based on Fox's formula, just like the Tg of polymer (A).

[0103] The Mw of the acrylic oligomer is not particularly limited; for example, it may be approximately 1000 or more, approximately 1500 or more is appropriate, approximately 2000 or more, or approximately 3000 or more. Furthermore, the Mw of the acrylic oligomer may be approximately less than 30000, approximately less than 10000 is appropriate, approximately less than 7000, or approximately less than 5000. When the Mw is within the above range, the effect of improving the cohesiveness of the adhesive layer and adhesion to adjacent surfaces is favorably exhibited. The Mw of the acrylic oligomer can be measured by GPC and determined as a value equivalent to standard polystyrene. Specifically, for example, it can be measured using an HPLC8020 manufactured by Tosoh Corporation with two TSKgelGMH-H(20) columns at a flow rate of approximately 0.5 mL / min using tetrahydrofuran solvent.

[0104] The monomer components that make up the acrylic oligomers are the various (meth)acrylic acid C compounds mentioned above. 1-20 Examples of (meth)acrylate monomers include alkyl esters; various alicyclic hydrocarbon group-containing (meth)acrylates mentioned above; various aromatic hydrocarbon group-containing (meth)acrylates mentioned above; and (meth)acrylates obtained from terpene compound derivative alcohols. These can be used individually or in combination of two or more.

[0105] From the viewpoint of improving adhesion, it is preferable that acrylic oligomers contain relatively bulky acrylic monomers as monomer units, such as alkyl(meth)acrylates with branched alkyl groups like isobutyl(meth)acrylate and t-butyl(meth)acrylate; alicyclic hydrocarbon group-containing(meth)acrylates; and aromatic hydrocarbon group-containing(meth)acrylates. Furthermore, when ultraviolet light is used during the synthesis of acrylic oligomers or the preparation of adhesive layers, monomers having saturated hydrocarbon groups at the ester terminus are preferred because they are less likely to inhibit polymerization. For example, alkyl(meth)acrylates with branched alkyl groups and saturated alicyclic hydrocarbon group-containing(meth)acrylates can be suitably used.

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

[0107] In addition to the (meth)acrylate monomers mentioned above, functional group-containing monomers can be used as constituent monomers of acrylic oligomers as needed. Examples of functional group-containing monomers include monomers having nitrogen atom-containing heterocycles such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; monomers containing amino groups such as N,N-dimethylaminoethyl (meth)acrylate; monomers containing amide groups such as N,N-diethyl (meth)acrylamide; monomers containing carboxyl groups such as AA and MAA; and monomers containing hydroxyl groups such as 2-hydroxyethyl (meth)acrylate. These functional group-containing monomers can be used individually or in combination of two or more. When functional group-containing monomers are used, the proportion of functional group-containing monomers in the total monomer components constituting the acrylic oligomer can be, for example, 1% or more by weight, 2% or more by weight, or 3% or more by weight, and can also be, for example, 15% or less by weight, 10% or less by weight, or 7% or less by weight. Acrylic oligomers may also be those that do not use functional group-containing monomers.

[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), copolymers of CHMA and AA, and the like.

[0109] Acrylic oligomers can be formed by polymerizing their 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 employed in appropriate manner. The types of polymerization initiators that can be used as needed (e.g., azo polymerization initiators) are generally as exemplified for the synthesis of acrylic polymer (A), and the amount of polymerization initiator and the amount of chain transfer agent (e.g., mercaptans) used as needed are appropriately set based on common technical knowledge to achieve the desired molecular weight, so a detailed explanation is omitted.

[0110] When an acrylic oligomer is included in the adhesive layer or adhesive composition, its content can be, for example, 0.01 parts by weight or more per 100 parts by weight of polymer (A), and may be 0.05 parts by weight or more, or 0.1 parts by weight or more, or 0.2 parts by weight or more, from the viewpoint of obtaining a higher effect. Furthermore, from the viewpoint of compatibility with polymer (A), it is appropriate that the content of the acrylic oligomer per 100 parts by weight of polymer (A) be 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, or 5 parts by weight or less, or 1 part by weight or less. An adhesive layer or adhesive composition that does not contain an acrylic oligomer is also acceptable.

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

[0112] The type of crosslinking agent is not particularly limited, and can be selected from conventionally known crosslinking agents, for example, depending on the composition of the adhesive composition, so that the crosslinking agent exhibits appropriate crosslinking function within the adhesive layer. 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, amine-based crosslinking agents, and the like. These can be used individually or in combination of two or more.

[0113] As isocyanate crosslinking agents, polyfunctional isocyanate compounds with two or more functions can be used. Examples include aromatic isocyanates such as tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, and diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate. 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"), isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate HX"), and trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, product name "Takenate D-110N").

[0114] As an epoxy crosslinking agent, any agent having two or more epoxy groups in one molecule can be used without particular limitation. Epoxy crosslinking agents having 3 to 5 epoxy groups in one molecule are preferred. Specific examples of epoxy crosslinking agents include N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available epoxy crosslinking agents include "TETRAD-X" and "TETRAD-C" from Mitsubishi Gas Chemical Company, "Epiclon CR-5L" from DIC Corporation, "Denacol EX-512" from Nagase ChemteX Corporation, and "TEPIC-G" from Nissan Chemical Industries, Ltd.

[0115] As an oxazoline crosslinking agent, any agent having one or more oxazoline groups in one molecule can be used without particular limitation. Examples of aziridine crosslinking agents include trimethylolpropantris[3-(1-aziridinyl)propionate] and trimethylolpropantris[3-(1-(2-methyl)aziridinylpropionate)]. As the carbodiimide crosslinking agent, low-molecular-weight or high-molecular-weight compounds 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, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate, and dibenzoyl peroxide. Among these, di(4-t-butylcyclohexyl)peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide are particularly excellent in crosslinking reaction efficiency. When peroxides are used as polymerization initiators, any remaining peroxide that is not used in the polymerization reaction can also be used in the crosslinking reaction. In that case, the amount of remaining peroxide should be quantified, and if the proportion of peroxide is less than a predetermined amount, peroxide should be added as needed to reach the predetermined amount. The quantification of peroxide can be carried out by the method described in Japanese Patent Publication No. 4971517.

[0117] The amount of crosslinking agent used (or the total amount if two or more crosslinking agents are used) is not particularly limited. From the viewpoint of realizing an adhesive that exhibits a good balance of adhesive properties such as adhesion and cohesiveness, it is appropriate to use approximately 5 parts by weight or less of crosslinking agent per 100 parts by weight of polymer (A), but it may also 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 embodiments in which a crosslinking agent and a photoreactive monomer (B) are used in combination, from the viewpoint of making it easier to suitably exhibit the effects of such combination use, the amount of crosslinking agent used per 100 parts by weight of 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 crosslinking agent used is not particularly limited, and it may be used in an amount greater than 0 parts by weight per 100 parts by weight of polymer (A). In some embodiments, the amount of crosslinking agent used may be, for example, 0.001 parts by weight or more, 0.01 parts by weight or more, or 0.03 parts by weight or more, per 100 parts by weight of polymer (A).

[0118] The technologies disclosed herein can preferably be implemented in a manner in which at least an isocyanate-based crosslinking agent is used as the crosslinking agent. An isocyanate-based crosslinking agent may be used in combination with other crosslinking agents. In the embodiment in which an isocyanate-based crosslinking agent is used, the amount of isocyanate-based crosslinking agent used per 100 parts by weight of 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. Alternatively, the amount of isocyanate-based crosslinking agent used per 100 parts by weight of 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 more effectively advance the crosslinking reaction. Examples of crosslinking catalysts include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, ferric narcem, butyltin oxide, and dioctyltin dilaurate. Among these, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred. The amount of crosslinking catalyst used is not particularly limited. The amount of crosslinking catalyst used can be, for example, approximately 0.0001 parts by weight or more, approximately 0.001 parts by weight or more, approximately 0.005 parts by weight or more, or approximately 1 part by weight or less, approximately 0.1 parts by weight or less, approximately 0.05 parts by weight or less, per 100 parts by weight of polymer (A).

[0120] The adhesive composition used to form the adhesive layer may optionally contain a compound that induces keto-enol tautomerism as a crosslinking retarder. For example, in an adhesive composition containing an isocyanate crosslinking agent or an adhesive composition that may be used with an isocyanate crosslinking agent, a compound that induces keto-enol tautomerism can be preferably used. This can extend the pot life of the adhesive composition. Various β-dicarbonyl compounds can be used as compounds that exhibit keto-enol tautomerism. Specific examples include β-diketones such as acetylacetone and 2,4-hexanedione; acetoacetate esters such as methyl acetoacetate and ethyl acetoacetate; propionyl acetate esters such as ethyl propionylacetate; isobutyryl acetate esters such as ethyl isobutyrylacetate; and malonic acid esters such as methyl malonate and ethyl malonate. Among these, acetylacetone and acetoacetate esters are particularly preferred. The compounds exhibiting keto-enol tautomerism can be used individually or in combination of two or more. The amount of compound that produces keto-enol tautomerism may be, for example, 0.1 parts by weight or more and 20 parts by weight or less per 100 parts by weight of polymer (A), preferably 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 1 part by weight or more and 5 parts by weight or less.

[0121] (Silane coupling agent) The adhesive layer disclosed herein may optionally contain a silane coupling agent. The use of a silane coupling agent can improve the peel strength of the adhesive layer from the adherend (e.g., a glass plate). An adhesive layer containing a silane coupling agent can be suitably formed using an adhesive composition containing a silane coupling agent. In such an adhesive composition, the silane coupling agent is preferably included in the adhesive composition in a free form from the viewpoint of suppressing gelation, etc. Furthermore, in some embodiments, the silane coupling agent is preferably included in the adhesive layer disclosed herein in a free form. A silane coupling agent included in the adhesive layer in such a form can effectively contribute to improving the peel strength. Herein, "free form" means that the silane coupling agent is not chemically bonded to other components contained in the adhesive composition or adhesive layer.

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

[0123] The amount of silane coupling agent used when using a silane coupling agent can be set to obtain the desired effect and is not particularly limited. In some embodiments, the amount of silane coupling agent used may be, for example, 0.001 parts by weight or more per 100 parts by weight of 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. Furthermore, from the viewpoint of suppressing gelation of the adhesive composition, it is appropriate to use 3 parts by weight or less per 100 parts by weight of polymer (A), and it may be 1 part by weight or less, or 0.5 parts by weight or less.

[0124] (Photopolymerization initiator) The adhesive layer disclosed herein may contain a photopolymerization initiator as needed for the purpose of improving or imparting photocurability. As the photopolymerization initiator, similar to the photopolymerization initiators exemplified for use in the synthesis of polymer (A), 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, thioxanthone-based photopolymerization initiators, etc. The photopolymerization initiator may be used individually or in appropriate combinations of two or more types.

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

[0126] The content of the photopolymerization initiator in the adhesive layer is not particularly limited and can be set so as to appropriately exhibit the desired effect. In some embodiments, the content of the photopolymerization initiator can be, for example, approximately 0.005 parts by weight or more, preferably 0.01 parts by weight or more, preferably 0.05 parts by weight or more, and may also be 0.10 parts by weight or more, 0.15 parts by weight or more, or 0.20 parts by weight or more, per 100 parts by weight of polymer (A) contained in the adhesive layer. Increasing the content of the photopolymerization initiator tends to improve the photocurability of the adhesive layer. Furthermore, the content of the photopolymerization initiator per 100 parts by weight of polymer (A) is appropriately 10 parts by weight or less, preferably 7 parts by weight or less, and may also be 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less. Not having too much photopolymerization initiator content can be advantageous from the viewpoint of improving storage stability (e.g., stability against photodegradation).

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

[0128] The adhesive layers or adhesive compositions disclosed herein may optionally contain, as needed, various additives common in the field of adhesives, such as tackifying resins (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based tackifying resins), viscosity modifiers (e.g., thickeners), leveling agents, plasticizers, fillers, colorants such as pigments and dyes, stabilizers, preservatives, and anti-aging agents. Such additives can be conventionally used by conventional methods and do not particularly characterize the present invention, so a detailed explanation is omitted. Furthermore, the technology disclosed herein can exhibit good adhesive strength without using the tackifying resin described above. For this reason, in some embodiments, the content of the tackifying resin in the adhesive layer or adhesive composition may be, for example, less than 10 parts by weight, or even less than 5 parts by weight, per 100 parts by weight of polymer (A). The content of the tackifying resin may 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 adhesive layer or adhesive composition may not contain the tackifying resin.

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

[0130] <Form of adhesive composition> The adhesive layer can be formed using an adhesive composition containing monomer components having the above-described composition in the form of polymers, unpolymerized products (i.e., in a form where polymerizable functional groups are unreacted), or mixtures thereof. The above adhesive composition can take various forms, such as a composition containing an adhesive (adhesive component) in an organic solvent (solvent-type adhesive composition), a composition in which the adhesive is dispersed in an aqueous solvent (water-dispersible adhesive composition), a composition prepared to form an adhesive by curing with active energy rays such as ultraviolet light or radiation (active energy ray-curable adhesive composition), or a hot-melt type adhesive composition that is applied in a heated 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, solvent-type adhesive compositions can be preferably used in some embodiments. Solvent-type adhesive compositions can preferably be prepared using a polymer (A), which is a polymer obtained by solution polymerization of monomer components.

[0131] In this specification, "active energy rays" refers to energy rays that have the energy to trigger chemical reactions such as polymerization reactions, crosslinking reactions, and initiator decomposition. Examples of active energy rays include light such as ultraviolet rays, visible light, and infrared rays, as well as radiation such as alpha rays, beta rays, gamma rays, electron beams, neutron beams, and X-rays.

[0132] The above adhesive composition typically contains at least a portion of the monomer components of the composition (which may be a portion of the types of monomers or a portion of the quantities) in the form of a polymer. The polymerization method used to form the polymer is not particularly limited, and various conventionally known polymerization methods can be used as appropriate. 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 irradiation with light such as ultraviolet light (typically carried out in the presence of a photopolymerization initiator); and radiation polymerization carried out by irradiation with radiation such as beta rays and gamma rays can be used as appropriate. In these polymerization methods, the mode of polymerization is not particularly limited, and conventionally known monomer supply methods, polymerization conditions (temperature, time, pressure, light irradiation amount, radiation irradiation amount, etc.), and materials other than monomers used (polymerization initiators, surfactants, etc.) can be appropriately selected.

[0133] In polymerization, known or conventional photopolymerization initiators or thermal polymerization initiators may be used depending on the polymerization method and polymerization mode. Examples of photopolymerization initiators and thermal polymerization initiators are as described above, so redundant explanations will be omitted. Such polymerization initiators can be used individually or in appropriate combinations of two or more.

[0134] (An adhesive composition containing polymers and unpolymerized monomer components) Adhesive compositions according to several embodiments include a polymerization product of a monomer mixture containing at least a portion of the monomer components (raw material monomers) of the composition. Typically, the monomer components are contained in the form of a polymer, with the remainder in the form of an unpolymerized product (unreacted monomer). The polymerization product of the monomer mixture can be prepared by polymerizing the monomer mixture at least partially. The polymerization reaction product described above is preferably a partial polymer of the monomer mixture. Such a partial polymer is a mixture of polymers derived from the monomer mixture and unreacted monomers, and typically exhibits a syrup-like (viscous liquid) state. Hereinafter, a partial polymer with such properties may be referred to as "monomer syrup," "polymer syrup," or simply "syrup."

[0135] The polymerization method used to obtain the above-mentioned 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, photopolymerization can be preferably employed. With photopolymerization, the polymerization conversion rate of the monomer mixture can be easily controlled by polymerization conditions such as the amount of light irradiation (light intensity).

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

[0137] An adhesive composition containing a partially polymerized product of the above monomer mixture can be easily obtained, for example, by partially polymerizing a monomer mixture containing all of the raw material monomers using a suitable polymerization method (e.g., photopolymerization). The adhesive composition containing the above partially polymerized product may contain other components as needed (e.g., photopolymerization initiators, polyfunctional monomers, crosslinking agents, acrylic oligomers described later, etc.). The method of incorporating such other components is not particularly limited; for example, they may be included in the monomer mixture beforehand or added to the above partially polymerized product.

[0138] Furthermore, the adhesive compositions 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 material monomers) is dissolved in the remaining types of monomers or their partial polymers. Such forms of adhesive compositions are also included as examples of adhesive compositions containing polymers and unpolymerized monomer components. In this specification, "complete polymer" means a polymerization conversion rate of more than 95% by weight.

[0139] As a curing method (polymerization method) when forming an adhesive from an adhesive composition containing polymers and unpolymerized monomer components, photopolymerization can be preferably employed. In adhesive compositions containing polymerization reaction products prepared by photopolymerization, photopolymerization is particularly preferred as the curing method. Since the polymerization reaction product obtained by photopolymerization already contains a photopolymerization initiator, when further curing the adhesive composition containing this polymerization reaction product to form an adhesive, photocuring is possible without adding a new photopolymerization initiator. Alternatively, the adhesive composition may have a composition in which a photopolymerization initiator is added as needed to the polymerization reaction product prepared by photopolymerization. The added photopolymerization initiator may be the same as or different from the photopolymerization initiator used to prepare the polymerization reaction product. Adhesive compositions prepared by methods other than photopolymerization can be made photocurable by adding a photopolymerization initiator. Photocurable adhesive compositions have the advantage that even thick adhesive layers can be easily formed. In some preferred embodiments, photopolymerization when forming an adhesive from an adhesive composition can be carried out by ultraviolet irradiation. For ultraviolet irradiation, known high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, etc., can be used.

[0140] (An adhesive composition containing monomer components in the form of a complete polymer) Adhesive compositions according to several other embodiments include the monomer component of the adhesive composition in the form of a complete polymer. Such adhesive compositions may take the form of, for example, a solvent-type adhesive composition containing an acrylic polymer, which is a complete polymer of the monomer component, in an organic solvent, or a water-dispersible adhesive composition in which the acrylic polymer is dispersed in an aqueous solvent.

[0141] (Formation of the adhesive layer) The method for forming the adhesive layer is not particularly limited. For example, an adhesive layer can be formed on the release surface of a release film by applying an adhesive composition to the release surface and drying (e.g., heat drying) or curing it. Alternatively, an adhesive layer can be formed by drying or curing an adhesive composition sandwiched between two release films. The curing treatment may include crosslinking (e.g., crosslinking by the reaction of the crosslinking agent described above), cooling, etc. When two or more curing treatments are performed, they can be performed simultaneously or in stages. Various conventionally known methods can be used as the method for applying the adhesive composition. Specifically, 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, and extrusion coating methods using die coaters. Typically, by using a release film with a highly smooth release surface in which the maximum height (Rz) and arithmetic mean roughness (Ra) are limited to predetermined values ​​or less, a highly smooth adhesive surface can be manufactured stably (with good reproducibility). Furthermore, it is preferable to apply the adhesive composition at a temperature of 80°C or lower, and more preferably at a temperature of 60°C or lower (for example, 40°C or lower). This suppresses roughening of the adhesive layer due to the difference in thermal expansion coefficients between the release film and the adhesive layer, and can result in the formation of a smoother adhesive surface.

[0142] (Thickness of the adhesive layer) 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 suitable to be 5 μm or more, for example, may be 10 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and may be greater than 25 μm. As the thickness of the adhesive layer increases, the stress distribution ability of the adhesive layer tends to increase. This can advantageously contribute to the reduction of optical distortion. In addition, adhesive layers with greater thickness tend to have better step-following ability and can easily absorb deformation caused by foreign matter, etc. Impact resistance also tends to improve. The technology disclosed herein can preferably be 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, as the thickness of the adhesive layer increases, the optical path transmitted through the adhesive layer also becomes longer, making optical distortion more easily noticeable. For this reason, in some embodiments, the thickness of the adhesive layer is appropriately set to, for example, 200 μm or less, but may also 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 also be 35 μm or less. An adhesive layer having such a thickness can better suppress the deformation of the adhesive layer. According to the technology disclosed herein, a bond with high deformation resistance and high impact resistance can be formed with 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 with a flat probe.

[0143] (Peak top temperature of tanδ) The adhesive constituting the adhesive layer disclosed herein preferably has a peak top temperature of its loss tangent tanδ in the range of -50°C to 0°C. Adhesives with a tanδ peak top in the low-temperature region tend to provide good impact resistance. The peak top temperature of the loss tangent tanδ of the adhesive can be determined by the following method. That is, dynamic viscoelasticity measurements are performed under the same conditions as the measurement of the storage modulus at 25°C described below, and the storage modulus G' and loss modulus G'' are measured. Then, the loss tangent tanδ is calculated using the following equation: tanδ = G'' / G'; and by plotting its temperature dependence, the temperature corresponding to its peak top (the temperature at which the tanδ curve is maximum) can be determined.

[0144] (Storage modulus at 25°C) The storage modulus of the adhesive layer at 25°C (25°C storage modulus) is appropriately set according to the intended use and manner 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 25°C storage modulus is approximately 4 × 10⁻⁶. 4 It is appropriate to set it to Pa or higher, preferably about 6 × 10 4 Pa or higher, more preferably approximately 8 × 10 4 It is above Pa, approximately 1.0 × 10⁻⁶ 5 It may be Pa or higher, approximately 1.2 × 10 5 Pa or higher is also acceptable, approximately 1.5 × 10 5 A value of Pa or higher is sufficient, approximately 1.8 × 10 5 It may be Pa or higher. The adhesive layer with a high storage modulus at 25°C tends to have excellent resistance to compressive deformation. Also, the storage modulus at 25°C can be, for example, 1 × 10⁻⁶. 7 It is less than Pa, approximately 1 × 10 6 A value of Pa or less is appropriate. From the viewpoint of suitably exhibiting adhesive properties such as adhesion, the above 25°C storage modulus is preferably approximately 5.0 × 10⁻⁶. 5 Pa or less, more preferably approximately 3.0 × 10 5 Pa or less, more preferably about 2.0 × 10 5 It is less than Pa, approximately 1.4 × 10 5 It may be less than or equal to Pa, approximately 1.0 × 10 5It may be less than Pa. The 25°C storage modulus can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc., of the base polymer. The 25°C storage modulus is measured by the following method. The same applies to the examples described later.

[0145] [Storage modulus at 25°C] A layer of adhesive approximately 2 mm thick is prepared by stacking multiple adhesive layers to be measured. A sample of this adhesive layer, punched into a disc shape with a diameter of 7.9 mm, is sandwiched and fixed between parallel plates, and dynamic viscoelasticity measurements are performed using a viscoelasticity tester (e.g., ARES or equivalent manufactured by T.A. Instruments) under the following conditions to determine the storage modulus G'(25°C)[Pa] at 25°C. • Measurement mode: Shear mode Temperature range: -70℃ to 150℃ • Heating rate: 5°C / min ·Measurement frequency: 1Hz

[0146] (Gel fraction) The gel fraction of the adhesive layer is appropriately set according to the purpose and manner of use, and is not limited to a specific range. The gel fraction is, for example, approximately 99% by weight or less, and approximately 97% by weight or less is appropriate. From the viewpoint of step-following ability, in some preferred embodiments, the gel fraction is approximately 95% by weight or less, more preferably approximately 92% by weight or less, and may also be approximately 88% by weight or less, approximately 75% by weight or less, or approximately 65% ​​by weight or less. An adhesive layer having the above gel fraction can, for example, follow the irregularities of a print such as a logo mark formed on the surface of the adherend without impairing visibility. Furthermore, from the viewpoint of exhibiting good adhesive properties and viscoelastic properties, the gel fraction of the adhesive layer is, for example, approximately 10% by weight or more, and it is appropriate to set it to approximately 20% by weight or more. From the viewpoint of deformation resistance, the gel fraction is preferably approximately 30% by weight or more, more preferably approximately 40% by weight, and may be approximately 50% by weight or more, approximately 65% ​​by weight or more, or approximately 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 method described below. The same applies to the examples described later.

[0147] [Gel fraction] A predetermined amount of adhesive sample (weight Wg1) is wrapped in a drawstring-like shape with a porous polytetrafluoroethylene membrane (weight Wg2) having an average pore size of 0.2 μm, and the opening is tied with string (weight Wg3). As the porous polytetrafluoroethylene (PTFE) membrane, the product name "Nitoflon (registered trademark) NTF1122" (average pore size 0.2 μm, porosity 75%, thickness 85 μm) or an equivalent product available from Nitto Denko Corporation 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 from the film. Then the package is removed, the ethyl acetate adhering to the outer surface is wiped off, and the package is dried at 130°C for 2 hours. The weight of the package (Wg4) is then measured. The gel fraction of the adhesive layer can be determined by substituting each value into the following formula. Gel fraction (%) = [(Wg4 - Wg2 - Wg3) / Wg1] × 100

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

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

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

[0151] Furthermore, the total light transmittance and haze value of the adhesive layer can be measured by attaching the adhesive layer to be measured to one side of a glass plate and using a haze meter. A haze meter such as the "HM-150N" manufactured by Murakami Color Technology Laboratory or an equivalent product can be used. Specifically, the measurements are performed using the method described in the examples below.

[0152] The adhesive layer having the total light transmittance and haze value described above may be a colored transparent or colorless transparent adhesive layer. Furthermore, the optical distortion reduction effect of the adhesive layer according to the technology disclosed herein can be achieved in a configuration in which at least a portion of the surface of the adhesive layer has a degree of transparency that allows visibility through the adhesive layer; therefore, the adhesive layer does not need to be transparent or translucent.

[0153] (Surface properties of the adhesive surface) The adhesive layer disclosed herein preferably has an adhesive surface (including a first adhesive surface and a second adhesive surface; the same applies hereinafter unless otherwise specified) in which the maximum height Rz is limited to a predetermined value or less. A configuration with an adhesive surface designed to have a low maximum height Rz can have high surface smoothness and may be free from or have suppressed optical distortion. Such an adhesive layer may not impair the design of the adherend, or, for example, its aesthetics or sense of luxury, 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, approximately 2000 nm or less, preferably approximately 1000 nm or less, more preferably approximately 600 nm or less, more preferably approximately 500 nm or less, even more preferably approximately 450 nm or less, particularly preferably approximately 400 nm or less, and may be less than 350 nm, less than 300 nm, or less than 250 nm. 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, approximately 10 nm or more, approximately 50 nm or more, approximately 100 nm or more, or approximately 200 nm or more. The maximum height Rz of the first adhesive surface and the maximum height Rz of the second adhesive surface of the adhesive layer may be about the same or different.

[0155] The adhesive surface of the adhesive layer disclosed herein preferably has an arithmetic mean roughness Ra limited to a predetermined value or less. A configuration with an adhesive surface designed to have a low arithmetic mean roughness Ra makes it easier to suppress optical distortion to a high degree.

[0156] The arithmetic mean roughness Ra of the adhesive surface of the adhesive layer is, for example, approximately 300 nm or less, preferably approximately 150 nm or less, more preferably approximately 70 nm or less, more preferably approximately 65 nm or less, and even more preferably approximately 55 nm or less. It may also be less than 50 nm, less than 45 nm, or 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, approximately 10 nm or more, approximately 20 nm or more, or approximately 30 nm or more (for example, approximately 40 nm or more). The arithmetic mean roughness Ra of the first adhesive surface and the arithmetic mean roughness Ra of the second adhesive surface of the adhesive layer may be of the same magnitude or may be different.

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

[0158] Furthermore, the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the adhesive layer are measured on the adhesive surface of the adhesive layer after the release film has been peeled off, using a non-contact surface roughness measuring device. As the non-contact surface roughness measuring device, an optical interference type surface roughness measuring device is used, for example, a 3D optical profiler (product name "NewView7300", manufactured by ZYGO) or an 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 those measurement conditions.

[0159] (Adhesion strength to transparent materials) The adhesive strength of the adhesive layer disclosed herein is not particularly limited and can be set according to the purpose. In some embodiments, the adhesive strength of the adhesive layer to the transparent member is suitable to be, for example, approximately 1.0 N / 20 mm or more, and may be approximately 3.0 N / 20 mm or more (for example, approximately 5.0 N / 20 mm or more). In other words, it can be said that the adhesive layer adheres to the transparent member with the above adhesive strength. By ensuring good adhesion between the transparent member and the adhesive layer in this way, the laminate can exhibit good durability against impacts and the like. From the viewpoint of bonding reliability, the above adhesive strength is preferably approximately 7.0 N / 20 mm or more, more preferably approximately 8.0 N / 20 mm or more, even more preferably approximately 9.0 N / 20 mm or more, and may also be approximately 10.0 N / 20 mm or more, or approximately 11.0 N / 20 mm or more. Furthermore, from the viewpoint of easily balancing with other characteristics, the above adhesive strength may be, for example, approximately 20 N / 20 mm or less, approximately 16.0 N / 20 mm or less, or approximately 12.0 N / 20 mm or less. The above adhesive strength can be adjusted by selecting the composition and thickness of the adhesive layer, etc.

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

[0161] (Module of elasticity determined by tensile testing) In some preferred embodiments, the adhesive layer has an elastic modulus (also called initial modulus) of 3.0 MPa or higher as determined by a tensile test. Adhesive layers with higher elastic moduli tend to exhibit better deformation resistance. In embodiments where two members (typically a transparent member and a decorative film) are joined via an adhesive layer in a laminate, high deformation resistance of the adhesive layer can help maintain the relative positions of the two members with precision. Furthermore, in embodiments where, for example, a decorative film and a transparent member are joined via an adhesive layer, high deformation resistance of the adhesive layer can help suppress the phenomenon of changes in the appearance of the laminate due to localized pressure from the decorative film side (pressure deformation resistance).

[0162] In some preferred embodiments of the adhesive layer, the modulus of elasticity may be, for example, 5.0 MPa or higher, 7.0 MPa or higher, 10.0 MPa or higher, 15.0 MPa or higher, or 20.0 MPa or higher. Deformation resistance tends to improve with increasing modulus of elasticity. There is no particular upper limit to the modulus of elasticity. From the viewpoint of easily balancing with other properties (e.g., one or more properties selected from impact resistance, adhesive strength, haze value, etc.), it is advantageous for the modulus of elasticity to be 150 MPa or lower, preferably 120 MPa or lower, and may also be 100 MPa or lower, 80 MPa or lower, or 60 MPa or lower. The modulus of elasticity determined by the tensile test can be adjusted by selecting the composition of the adhesive layer, etc. The modulus of elasticity determined by the tensile test is measured by the tensile test described above. More specifically, it is measured by the method described in the examples described later.

[0163] (Impact resistance) The adhesive layer disclosed herein has an impact resistance of 2.0 J / 10 mm 2 The above is preferable. With the above impact-resistant adhesive layer, a highly reliable bond can be formed. Such an adhesive layer can withstand impacts such as drops or collisions and maintain a good bond state in the laminate.

[0164] In some preferred embodiments of the adhesive layer, the impact resistance is, for example, 2.1 J / 10 mm 2 The above is sufficient, 2.3J / 10mm 2 The above is also acceptable, 2.5J / 10mm 2 The above is also acceptable, 2.7J / 10mm 2 The above is also acceptable, 3.0J / 10mm 2 The above is also acceptable. The laminate disclosed herein has an impact resistance of 3.3 J / 10 mm² for the adhesive layer. 2 or larger or 3.5J / 10mm 2 The above-mentioned embodiments may also be preferably implemented. The upper limit of the above impact resistance is not particularly limited. From the viewpoint of easily balancing with other characteristics, the above impact resistance may be, for example, 20J / 10mm 2 The following are acceptable: 15J / 10mm 2 The following is also acceptable: 10J / 10mm 2 The following is also acceptable: 8.0J / 10mm 2 The following is also acceptable: 6.0J / 10mm 2 The following is also acceptable. Impact resistance can be adjusted by selecting the composition and thickness of the adhesive layer. Impact resistance is measured by the shear impact test described above. More specifically, it is measured by the method described in the examples below.

[0165] Furthermore, since the adhesive layer disclosed herein includes a method of photocuring after being bonded to an adherend, at least for the photocurable adhesive layer (for example, adhesive C in the examples described later), an illuminance of 300 mW / cm² is required. 2 , cumulative light intensity 3000 mJ / cm 2 The measurement samples, after being irradiated with ultraviolet light under the specified conditions and aged at 50°C for 48 hours, shall be used to measure the peak top temperature of tanδ, storage modulus at 25°C, gel fraction, total light transmittance, haze value, maximum height Rz of the adhesive surface, arithmetic mean roughness Ra, adhesive strength, modulus of elasticity by tensile test, and impact resistance. When the release film is transparent, it is preferable to perform the above ultraviolet light irradiation treatment with the adhesive layer sandwiched between transparent release films.

[0166] <Second adhesive layer> The technology disclosed herein can be implemented in the form of a laminate including a first adhesive layer and a second adhesive layer, as shown in Figure 4, for example. The first adhesive layer is disposed between the transparent member and the decorative film, and the second adhesive layer is disposed on the side of the decorative film opposite to the first adhesive layer. In this embodiment, the first adhesive layer and the second adhesive layer may have the same composition, structure, properties, etc., or they may be different. Based on the above description, the first adhesive layer and the second adhesive layer can each be designed independently to have a composition, structure, properties, etc., suitable for their purpose and application. For example, the second adhesive layer may not require the same visibility as the first adhesive layer due to its placement, and may have a different composition, structure, and properties than the first adhesive layer. Depending on the properties required for its placement, a known or conventional adhesive may be used as the second adhesive layer.

[0167] While not particularly limited, the second adhesive layer may have a lower total light transmittance than the first adhesive layer. The second adhesive layer may also have a higher haze value than the first adhesive layer. The second adhesive layer may be a colored adhesive layer (e.g., a black adhesive layer) and may function as a coloring layer. Furthermore, the maximum height Rz and arithmetic mean roughness Ra of the adhesive surface of the second adhesive layer are not particularly limited and may be similar to those of the first adhesive layer, but may also be higher.

[0168] In embodiments in which the laminate includes a first adhesive layer and a second adhesive layer, it is preferable to design the thickness of the second adhesive layer to be greater than the thickness of the first adhesive layer. By configuring it in this way, deformation resistance, including resistance to compressive deformation, can be preferably ensured by the second adhesive layer. This increases the design freedom of the first adhesive layer, which is located on the visible side of the decorative film, and allows for a favorable improvement in the overall performance of the laminate, for example, by reducing optical distortion with the first adhesive layer and improving deformation resistance with the second adhesive layer. Although not particularly limited, the thickness of the second adhesive layer can be 1.2 times or more (for example, about 1.2 to 5 times) the thickness of the first adhesive layer, and may be 1.5 times or more, or even 2 times or more.

[0169] <Applying the adhesive layer> The method for attaching the adhesive layer disclosed herein to an adherend is not particularly limited. Known or conventional bonding methods can be adopted according to the intended use and manner of use. In some preferred embodiments, the above attachment may be performed by a method that includes photocuring the adhesive layer after it has been bonded to the adherend (specifically, a transparent member or decorative film). By bonding the adhesive layer to the adherend (specifically, a transparent member or decorative film), a laminate in which the adhesive layers are stacked is formed. By photocuring this adhesive layer, a laminate including the cured adhesive layer and the adherend (specifically, a transparent member or decorative film) is obtained. Therefore, this specification provides a method for manufacturing a laminate, which includes bonding one of the adhesive layers disclosed herein to an adherend (specifically, a transparent member or decorative film), and photocuring the adhesive layer by irradiating it with ultraviolet light (for example, through a transparent member).

[0170] <Laminated structure of transparent material 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, approximately 50% or more, and preferably approximately 70% or more. From the viewpoint of the visibility of the decorative film through the transparent member and the adhesive layer, in some preferred embodiments, the total light transmittance of the above laminated structure is approximately 85% or more, and more preferably approximately 90% or more. Theoretically, the upper limit of the above total light transmittance is 100% minus the light loss due to reflection at the air interface (Fresnel loss), and in practical terms, it may be approximately 95% or less, and even if it is approximately 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, approximately 10% or less, and preferably approximately 3% or less. From the viewpoint of visibility through the transparent member and the adhesive layer, in some preferred embodiments, the haze value of the above laminated structure is approximately 1% or less, more preferably approximately 0.8% or less, and may also be 0.5% or less. The lower limit of the above haze value is theoretically 0%, and in practice, may be approximately greater than 0.0%.

[0172] Furthermore, the total light transmittance and haze value of the laminated structure of the transparent material and adhesive layer can be measured using a haze meter. For the haze meter, the "HM-150N" manufactured by Murakami Color Technology Laboratory or an equivalent product can be used.

[0173] <Decorative film> The laminate disclosed herein includes a decorative film. Here, a decorative film refers to a film having a design on its surface (decorative surface), and is also called a design film or decorative film. The decorative film includes components that perform decorative and protective roles while maintaining the visibility of image display devices and input devices. Examples of decorative films include films having a decorative layer that provides a desired appearance (printed layer, laminate layer, colored layer, glossy layer, continuous or discontinuous inorganic layer (metal layer, metal oxide layer, etc.)). The decorative film may have a design on its surface while exhibiting good opacity.

[0174] The decorative film described above may have a decorative layer. Examples of the decorative layer include, for example, a printed layer, a laminate layer, a colored layer, a glossy layer, and a continuous or discontinuous inorganic layer that provides a desired appearance. Examples of continuous or discontinuous inorganic layers 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 their alloys. Examples of the metal oxide include chromium oxide, indium oxide, zinc oxide, and titanium oxide. The metal layer and metal oxide layer can be formed by vapor deposition, sputtering, etc. A typical example of a decorative film is a metallic-looking film. A metallic-looking decorative film may have electromagnetic wave transmission properties in addition to metallic luster. Examples of such decorative films include electromagnetic wave-transmitting metallic glossy members as described in Japanese Patent Publication No. 2018-69462, Japanese Patent Publication No. 2019-123238, and Japanese Patent Publication No. 2019-188805.

[0175] Furthermore, the decorative film may specifically have a base layer, comprising a base layer and a decorative layer covering at least a portion of at least one surface of the base layer. Various resin films such as plastic films can be used as the base layer. 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 triacetylcellulose; acetate resins; polysulfone resins; polyethersulfone resins; polycarbonate resins; polyamide resins; polyimide resins; norbornene resins; cyclic polyolefin 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 more of these resins can be used. Among these, 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 placed on the adhesive layer side of the substrate layer, on the opposite side from 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 in the range of approximately 1 to 1000 nm, for example, it may be about 1 to 300 nm or about 1 to 200 nm. Furthermore, the sheet resistance of the decorative layer is preferably 100 Ω / □ or more, for example, it may be 250 Ω / □ or more or 1000 Ω / □ or more. A decorative film having such a decorative layer can be radio wave transparent, and can therefore be preferably used in various applications where radio wave transparency is required, such as portable electronic devices. The upper limit of the sheet resistance of the decorative layer is not particularly limited, for example, 1 × 10 16 The value may be less than or equal to Ω / □. The sheet resistance can be measured based on the overcurrent measurement method described in JIS Z 2316. The same method is used in the embodiments described later.

[0177] Furthermore, the visible light transmittance of the decorative film is appropriately less than 30% from the viewpoint of opacity and light shielding, may be less than 20%, preferably less than 10%, and may be 7.0% or less. The lower limit of the above visible light transmittance is 0%, may be 1% or more, and 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. The visible light transmittance of the decorative film is determined by measuring the transmittance in the visible light region (380~780nm) with a spectrophotometer. The same method is used in the examples described later.

[0178] The design-forming surface of the decorative film may have a flat plane, or it may have irregularities such as printed logos or engravings. The adhesive layer disclosed herein may have excellent step-following properties and can therefore adhere well to the surface of the decorative film having the irregularities.

[0179] Furthermore, the adhesive layer side surface of the decorative film may be subjected to surface treatments such as the application of a primer, corona discharge treatment, or plasma treatment. Such surface treatments can help improve 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 located 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 the adhesive layer. The colored layer may also be located on the outer surface of the transparent member. A laminate having a colored layer can achieve high opacity.

[0181] The colored layer to be placed in the laminate is not particularly limited other than being 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, an adhesive layer, or a decorative film. Conventionally known pigments and dyes can be used as the colorant. The color of the colorant may be, for example, black, gray, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearl, white, etc. Black colorants tend to have excellent light-shielding properties and also tend to have excellent visibility, including machine discriminability, and design properties. From the viewpoint of obtaining excellent light-shielding properties, the use of black colorants is preferred. In that case, the colored layer is also called the black layer.

[0182] As a black coloring agent, organic or inorganic coloring agents (pigments, dyes, etc.) can be used. Specific examples of black coloring agents 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 coloring agents, etc. Among these, carbon black is preferred.

[0183] Any material known in the field of paints or printing can be used as the binder for the colored layer without particular limitations. Examples include polyurethane, phenolic resin, epoxy resin, urea-melamine resin, and polymethyl methacrylate. The composition for forming the colored layer may be solvent-based, UV-curing, or thermosetting. The colored layer can be formed by any means conventionally used for forming colored layers without particular limitations. For example, a method of forming the colored layer (printed layer) by printing such as gravure printing, flexographic printing, or offset printing can be preferably employed.

[0184] The above-mentioned colored layer may be a single-layer structure consisting of one layer, or it may be a multilayer structure including two, three or more sub-colored layers. A multilayer colored layer including two or more sub-colored layers can be formed, for example, by repeatedly applying (e.g., printing) a colored layer-forming composition. The color and amount of colorant contained in each sub-colored layer may be the same or different. For colored layers intended to provide light-shielding properties, a multilayer structure is particularly beneficial from the viewpoint of preventing the occurrence of pinholes and improving the reliability of light leakage prevention.

[0185] The colored layer (which may be a printed layer) described above may be formed over the entire surface, such as the surface of a transparent member or the surface of a decorative film, or it may be formed partially on the surface. Printed layers are suitable for partial formation. For example, in the laminate shown in Figures 2-4, the colored layer (printed layer) may be preferably used as the colored layer 40. When viewed from above, a partially placed colored layer may be, for example, text information, a design, or a pattern, and may be formed in an annular (frame-like) shape along the outer edge.

[0186] In some other embodiments, the colored layer is a resin film containing a colorant, which may be a resin film in which the colorant is mixed into 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, conventionally known pigments and dyes as exemplified above can be used. From the viewpoint of opacity, a black colorant is preferred, and carbon black is particularly preferred. The above-mentioned colored layer is preferably a black layer.

[0187] The above-mentioned colored resin film may contain various additives as needed, such as fillers (inorganic fillers, organic fillers, etc.), dispersants (surfactants, etc.), anti-aging agents, antioxidants, UV absorbers, antistatic agents, lubricants, and plasticizers.

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

[0189] The colored resin film layer described above may be arranged, for example, on the side opposite to the adhesive layer of the decorative film, preferably across the entire surface. For example, in the laminate shown in Figures 3-4, the colored resin film layer (e.g., black resin film layer) may be preferably used as the colored layer 50.

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

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

[0192] Non-limiting examples of the above-mentioned portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (e.g., wristwear-type devices worn on the wrist like watches, modular devices attached to a part of the body with clips or straps, eyewear-type devices including glasses (monocular and binocular, including head-mounted types), clothing-type devices attached to shirts, socks, hats, etc. as accessories, earwear-type devices attached to the ears like earphones, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game consoles, electronic dictionaries, electronic organizers, e-books, in-car information systems, portable radios, portable televisions, portable printers, portable scanners, portable modems, etc. In this specification, "portable" means not merely being able to carry, but having a level of portability that allows an individual (a typical adult) to carry it relatively easily.

[0193] The matters disclosed in this specification include the following: [1] A laminate in which a transparent component, an adhesive layer, and a decorative film are arranged in this order. [2] The laminate according to [1], wherein the visible light transmittance in the lamination direction of the transparent member, the adhesive layer, and the decorative film is less than 10%. [3] The laminate according to [1] or [2] above, wherein the arithmetic mean roughness Ra of the adhesive layer surface is 70 nm or less and the maximum height Rz is 600 nm or less. [4] The laminate according to any one of [1] to [3] above, wherein the adhesive layer has a total light transmittance of 85% or more in the lamination direction and a haze value of 1% or less. [5] The storage modulus of the adhesive layer at 25°C is 4 × 10 4 A laminate according to any of the above [1] to [4], wherein the Pa is greater than or equal to Pa. [6] The laminate according to any one of [1] to [5] above, wherein the adhesive layer is bonded to the transparent member with a 180-degree peel strength greater than 7 N / 20 mm. [7] The laminate according to any one of [1] to [6] above, wherein the adhesive layer is an acrylic adhesive layer. [8] The laminate according to any one of [1] to [7] above, wherein the adhesive layer has an elastic modulus of 3.0 MPa or more as measured by the tensile test described below. [Tensile test] The aforementioned adhesive layer is subjected to an illuminance of 300 mW / cm². 2 , cumulative light intensity 3000 mJ / cm 2 The adhesive layer is irradiated with ultraviolet light under the specified conditions and aged at 50°C for 48 hours. After this, the adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test specimen. In an environment of 23°C and 50% RH, a tensile test is performed on the test specimen using a tensile testing machine with a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain a stress-displacement curve, and the modulus of elasticity [MPa] is calculated from its initial slope. [9] The adhesive layer has an impact resistance of 2.0 J / 10 mm as measured by the following shear impact test. 2The laminate described in any of the above [1] to [8]. [Shear impact test] A shear impact test will be performed using a pendulum-type adhesive shear impact tester based on JIS K6855. For the measurement sample, the first surface of the 10 mm square adhesive layer will be bonded to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate, and then the second surface of the adhesive layer will be bonded to the center of a 40 mm square stainless steel plate (SUS304BA plate). The samples will be pressed together with a load of 5 N for 10 seconds, followed by autoclaving (50°C, 0.5 MPa, 15 minutes), and an illuminance of 300 mW / cm² will be applied from the glass plate side. 2 , cumulative light intensity 3000 mJ / cm 2 The product used will have been irradiated with ultraviolet light under these conditions, followed by aging at 50°C for 48 hours. The measurement sample is fixed with the stainless steel plate facing downwards, and the absorbed energy [J] is measured when a hammer is struck against the outer surface of the glass plate under the conditions of hammer energy 2.75J and hammer speed 3.5m / sec in an environment of 23℃ and 50%RH, thereby determining the impact resistance [J / 10mm]. 2 Find the answer to ].

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

[11] The laminate according to

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

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

[11] above, wherein the decorative film comprises 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 in the range of 1 to 1000 nm.

[13] The laminate according to

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

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

[13] above, wherein the transparent member has a bent portion that bends in a straight line or a curved portion that curves in a curved shape in any cross section parallel to the lamination direction of the laminate, and the adhesive layer and the decorative film are arranged in the bent portion or the curved portion of the transparent member.

[15] It further has one or more colored layers, The laminate according to any one of [1] to

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

[16] A laminate according to any of [1] to

[15] above, used in portable electronic devices.

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

[16] above, wherein the gel fraction of the adhesive layer is 30 to 95% by weight.

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

[17] above, wherein the thickness of the adhesive layer is 5 to 100 μm.

[0194]

[19] The laminate according to

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

[20] The laminate according to

[11] or

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

[21] The laminate according to

[11] ,

[19] , or

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

[22] The laminate according to any one of

[11] ,

[19] to

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

[23] The laminate according to any one of

[11] ,

[19] to

[22] , wherein the adhesive layer comprises the above-mentioned compound B1 and compound B2 having two or more functional groups and no ring structure in the molecule as the above-mentioned photoreactive monomer (B).

[24] The laminate according to

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

[25] The laminate according to

[23] or

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

[26] The laminate according to any one of

[23] to

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

[27] The laminate according to any one of

[10] ,

[11] ,

[19] to

[26] , wherein the content of the photoreactive monomer (B) in the 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

[10] ,

[11] ,

[19] to

[27] above, 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

[10] ,

[11] ,

[19] to

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

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

[30] above, wherein the adhesive layer is crosslinked with a crosslinking agent.

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

[31] above, wherein the adhesive layer contains a photopolymerization initiator.

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

[32] above, wherein the adhesive layer contains a silane coupling agent.

[0195] The following describes some test examples relating to the present invention, but it is not intended to limit the present invention to those shown in the test examples. In the following description, "parts" and "%" refer to weight unless otherwise specified.

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

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

[0198] [Arithmetic mean roughness (Ra) and maximum height (Rz)] The arithmetic mean roughness (Ra) and maximum height (Rz) of the adhesive surface of an adhesive sheet (adhesive layer) are measured as follows: After peeling the release film from the adhesive sheet (adhesive layer) with a release film at a peeling angle of 180° and a speed of 300 mm / min, the exposed adhesive surface is left to stand for 30 minutes. The surface shape of the exposed adhesive surface is then measured using a 3D optical profiler (product name "NewView7300", manufactured by ZYGO) 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 determined as the sum of the height Rp of the highest peak above the mean line of the roughness curve obtained from the above measurement and the depth Rv of the deepest valley below the mean line. The measurement conditions are as follows: Ra and Rz are measured 5 times (i.e., N=5), and their 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 from plain glass using the silvering method is prepared, and it is confirmed to be distortion-free by visual inspection and by projecting a reflected image onto a screen using the same method as described below. In a clean room, after removing foreign matter from the surface of the mirror using a clean cloth, one side of the release film of the adhesive sheet with release film (adhesive layer) is peeled off from the adhesive sheet, and the mirror is attached to the surface of the mirror with appropriate tension to prevent foreign matter, air bubbles, or deformation streaks from getting into it, and degassing is performed using a pressurized degassing device (autoclave) to remove the effects 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 side of the 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 positioned with the adhesive sheet (adhesive layer) side facing the point light source, so that the angle with respect to the light rays from the point light source is approximately 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 Hamamatsu Photonics product name "Xenon Lamp C2577" or an equivalent product can be used. The point light source, evaluation sample, and screen should be 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 both approximately 50 cm. By illuminating the point light source and visually observing the image projected onto the screen by reflecting the sample, the presence and degree of optical distortion are evaluated at the following three levels. E: No optical distortion is observed. A: Some optical distortion is present, but it is at a level that is practically acceptable. P: Clear optical distortion is observed.

[0200] [Module of elasticity determined by tensile testing] A test specimen is prepared by cutting an adhesive sheet with a release film (adhesive layer) to a size of 10 mm in width and 150 mm in length. In an environment of 23°C and 50% RH, the two release films are peeled off to expose the adhesive layer, and a tensile test is performed on the above specimen using a tensile testing machine (device 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 the SS curve, and the modulus of elasticity [MPa] is calculated from its initial slope (the slope in the elastic deformation region of the above SS curve, specifically the slope in the range where the displacement is approximately less than 5%).

[0201] The thickness of the test specimen used in the above tensile test may be the same as, or different from, the thickness of the adhesive sheet (adhesive layer) as described above. For example, if the thickness of the adhesive sheet (adhesive layer) is relatively small, for the purpose of improving operability, etc., the results obtained from performing the above tensile test using a test specimen prepared to a thickness of 5 μm or more (for example, about 5 μm to 200 μm) 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 specimen can be adjusted by appropriately overlapping the adhesive layers before UV irradiation. Alternatively, a test specimen of a thickness suitable for tensile testing can be prepared using the same adhesive composition used to form the adhesive layer to be measured, and the results obtained from performing the above tensile test on that test specimen can be adopted as the elastic modulus of the adhesive layer. The above tensile test can be performed using a test specimen with a thickness of about 10 μm to 50 μm (preferably about 15 μm to 25 μm).

[0202] [Impact Resistance] A shear impact test is conducted using a pendulum-type adhesive shear impact tester based on JIS K 6855. As the measurement sample, an adhesive sheet with a release film (adhesive layer) is cut into a 10 mm square, one release film is peeled off to expose the first adhesive surface of the adhesive sheet (adhesive layer), the first adhesive surface is bonded to the central part of a chemically strengthened glass plate (manufactured by Corning) with a size of 25 mm square and a thickness of 1.7 mm. After that, the other release film is peeled off to expose the second adhesive surface of the above adhesive sheet (adhesive layer), the second adhesive surface is attached to the central part of a 40 mm square stainless steel plate (SUS304BA plate), and it is pressure-bonded with a 5 N weight for 10 seconds. Then, autoclave treatment (50 °C, 0.5 MPa, 15 minutes) is carried out, and ultraviolet rays are irradiated from the glass plate side using a high-pressure mercury lamp under the conditions of an illuminance of 300 mW / cm 2 , an integrated light quantity of 3000 mJ / cm 2 . After irradiation, the sample is aged at 50 °C for 48 hours and then used. The above measurement sample is fixed with the stainless steel plate on the lower side. In an environment of 23 °C and 50% RH, the impact resistance [J / 10 mm 2 is determined by measuring the absorbed energy [J] when a hammer is applied to the outer peripheral side surface of the glass plate under the conditions of a hammer energy of 2.75 J and a hammer speed (impact speed) of 3.5 m / s. The measurement is carried out 3 times, and their arithmetic mean value is adopted. In the case of an adhesive sheet protected by a release film with both sides being release surfaces, since one adhesive surface of the adhesive sheet unwound from the roll body is exposed, a chemically strengthened glass plate is bonded thereto, the other adhesive surface is peeled off from the release film to be exposed, and it is attached to the stainless steel plate to obtain a measurement sample, and then the measurement can be carried out.

[0203] The adhesive sheet (adhesive layer) disclosed here includes an adhesive sheet (adhesive layer) in a form where the adhesive layer is photocured after being bonded to the adherend. Therefore, at least for a photocurable adhesive sheet (for example, the adhesive sheet of Example 4 having Adhesive C described later), the illuminance is 300 mW / cm 2 , an integrated light quantity of 3000 mJ / cm 2Using the measurement sample after irradiating with ultraviolet rays under the following conditions and performing aging at 50°C for 48 hours, the 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, modulus of elasticity by tensile test) shall be carried out. Regarding the adhesion to glass, after pressure-bonding the photocurable adhesive sheet (for example, the adhesive sheet of Example 4 having Adhesive C described later) to the test plate, ultraviolet rays shall be irradiated under the above conditions and the measurement shall be carried out. Further, in the process of irradiating the above ultraviolet rays, when the release film is transparent, it is preferably carried out in a state where the above adhesive sheet (typically the adhesive layer) is sandwiched between transparent release films. It is desirable to measure the illuminance and light quantity of the light source by using an industrial UV checker (model "UVR-T2, light receiving part "UD-T36T2", manufactured by TOPCON Corporation) and adjusting the actual distance between the light source and the sample.

[0204] <Example 1> (Preparation of Adhesive Composition) 57 parts of n-butyl acrylate (BA) as a monomer component, 12 parts of cyclohexyl acrylate (CHA), 23 parts of 4-hydroxybutyl acrylate (4HBA), 8 parts of hydroxyethyl acrylate (HEA), 0.075 parts of the product named "Irgacure 651" (manufactured by BASF) and 0.075 parts of the product named "Irgacure 184" (manufactured by BASF) as a photoinitiator were blended. Then, this monomer mixture was exposed to ultraviolet rays in a nitrogen atmosphere and partially photopolymerized to obtain a partial polymer (acrylic polymer syrup) with a polymerization rate of about 10%. To 100 parts of the obtained acrylic polymer syrup, 0.14 parts of dipentaerythritol hexaacrylate (product name "KAYARAD DPHA", manufactured by Nippon Kayaku Co., Ltd.) and 0.3 parts of a silane coupling agent (product name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added and uniformly mixed to obtain an acrylic adhesive composition A.

[0205] (Production of Adhesive Sheet) As the first release film, a PET release film with a thickness of 75 μm was prepared, in which the first adhesive surface side surface S1, which is laminated on the first adhesive surface of the adhesive sheet, is a release surface treated with a silicone-based release agent, and the Ra of this surface S1 is 18 nm and the Rz is 223 nm. As the second release film, a PET release film with a thickness of 100 μm was prepared, in which the second adhesive surface side surface S2, which is laminated on the second adhesive surface of the adhesive sheet, is a release surface treated with a silicone-based release agent, and the Ra of this surface S2 is 18 nm and the Rz is 223 nm. The acrylic adhesive composition A obtained above was applied to the first adhesive side surface S1 of the first release film so that the thickness after the adhesive layer formation was 100 μm, thereby forming an adhesive composition layer. Next, the second release film was covered over the surface of the adhesive composition layer so that its second adhesive side surface S2 faced the adhesive composition layer. This shielded the adhesive composition layer from oxygen. Subsequently, the illuminance was set to 5 mW / cm². 2 , light intensity 2000mJ / cm 2 Under these conditions, ultraviolet irradiation was performed to photocur the adhesive composition layer, and a substrate-less double-sided adhesive sheet was prepared consisting only of an acrylic adhesive layer (also called adhesive A), with each side of the acrylic adhesive layer protected by first and second release films. The weight-average molecular weight (Mw) of the acrylic polymer used as the base polymer of the adhesive layer was 2 million.

[0206] <Example 2> As the first release film, a release film with an Ra of 18 nm and an Rz of 112 nm on the first adhesive surface side S1 was used, and as the second release film, a release film with an Ra of 18 nm and an Rz of 112 nm on the second adhesive surface side S2 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 prepared 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, 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. An acrylic adhesive composition B was obtained in the same manner as in Example 1, except that the obtained acrylic polymer syrup was used. Using the obtained acrylic adhesive composition B, a substrate-less double-sided adhesive sheet according to this example was prepared in the same manner as in Example 2, except that the thickness of the adhesive layer (also called adhesive B) was set to 50 μm.

[0208] <Example 4> (Preparation of adhesive composition) In a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer, 60 parts BA, 6 parts CHA, 18 parts NVP, 1 part isostearyl acrylate (iSTA), and 15 parts 4HBA were added as monomer components, 0.085 parts α-thioglycerol as a chain transfer agent, 0.2 parts 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and ethyl acetate as the polymerization solvent until the monomer components reached 45%. Nitrogen gas was then introduced, and the mixture was purged with nitrogen for approximately 1 hour while stirring. Subsequently, 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 by solids of trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, trade name "Takenate D-110N", solids concentration 75%) was added as an isocyanate crosslinking agent; 0.01 parts of dioctyltin dilaurate (manufactured by Tokyo Fine Chemical Co., Ltd., trade name "Envirizer OL-1") was added as a crosslinking accelerator; 4 parts of acetylacetone was added as a crosslinking retarder; 0.3 parts of 3-glycidoxypropyltrimethoxysilane (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a silane coupling agent; 8 parts of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name "A-DPH") and 12 parts of tricyclodecanedimethanol diacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name "A-DCP") were added as photoreactive monomers; and 1-hydroxycyclohexyl-phenyl-ketone (IGM) was added as a photopolymerization initiator. 0.7 parts of Regins' product, "Omnirad 184," were added and uniformly mixed to prepare adhesive composition C according to this example.

[0209] (Making adhesive sheets) As the first and second release films, release films having surfaces S1 and S2 with Ra and Rz as shown in Table 1 were used, respectively. The adhesive composition C obtained above was applied to the first adhesive side surface S1 of the first release film to a thickness of 20 μm after drying, and heated and dried at 60°C for 1 minute and 120°C for 3 minutes under normal pressure, followed by aging at 23°C for 120 hours to form a photocurable adhesive layer (substrate-less double-sided adhesive sheet). The second adhesive side surface S2 of the second release film was bonded to the surface of this photocurable adhesive layer for protection. In this way, a substrate-less double-sided adhesive sheet was produced consisting only of a photocurable acrylic adhesive layer (also called adhesive C), with each surface of the photocurable acrylic adhesive layer protected by the first and second release films.

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

[0211] <Fabrication of laminates> (Production of decorative film) A PET film manufactured by Mitsubishi Plastics, Inc. (125 μm thick, 340 mm wide) was prepared as the base film, and a 5 nm thick ITO layer was directly formed on it along the surface of the base film using DC magnetron sputtering. The temperature of the base film during ITO layer formation 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 using AC sputtering (AC: 40 kHz). The resulting Al layer was a discontinuous layer. The temperature of the base film during Al layer formation was set to 130°C. On the above Al layer, a 20 nm thick AlO layer was formed using RF (13.6 MHz) power sputtering. xA barrier layer was formed, and a metallic gloss film (decorative film) was obtained. The temperature of the substrate film during the formation of the barrier layer was set to room temperature. The sheet resistance of the Al layer and the ITO-containing layer of this decorative film was 3000 Ω / □ or more, and the visible light transmittance was 7% or less.

[0212] (Fabrication of laminates) For each example, the first release film of the adhesive sheet (adhesive layer) with a release film was peeled off to expose the first adhesive surface, and a 2kg roller was pressed onto a transparent component, a glass slide (manufactured by Matsunami Glass Industry Co., Ltd., product name "White Polishing No. 1", thickness 0.8-1.0 mm, total light transmittance 92%, haze value 0.2%), by one back-and-forth motion. 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 onto it, thereby creating a laminate in which the transparent component, adhesive layer, and decorative film were arranged in this order. The visible light transmittance of this laminate was 7% or less.

[0213] <Rating> For each example, the adhesive sheet with release film (adhesive layer) was evaluated for total light transmittance [%], haze value [%], adhesion strength to glass [N / 20mm], 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 elastic modulus of the adhesive sheet in Example 4 was measured by a tensile test, and impact resistance tests were performed on the adhesive sheets in Examples 1 to 4. Table 1 also shows an overview of each example (adhesive type, adhesive sheet (adhesive layer) thickness [μm], storage modulus at 25°C [Pa], gel fraction [%]).

[0214] [Table 1]

[0215] As shown in Table 1, no optical distortion was observed in the adhesive layers of Examples 1 to 5, or the optical distortion was within an acceptable range in practical use. From this result, it can be seen that when the above adhesive sheet (adhesive layer) is used in a laminate disposed between a transparent member and a decorative film, the design on the surface of the decorative film can be clearly visually recognized through the transparent member and the adhesive layer. The elastic modulus of the adhesive sheet (adhesive layer) according to Example 4 in the tensile test was 3.0 MPa or more, and the impact resistance of the adhesive sheets (adhesive layers) of Examples 1 to 4 was all 2.0 J / 10 mm 2 or more.

[0216] As described above, specific examples of the present invention have been described in detail, but 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 illustrated above.

Explanation of Reference Numerals

[0217] 1, 2, 3, 4 laminate 10 transparent member 10a first surface 10b second surface (surface on the adhesive layer side) 20 (first) adhesive layer 20a first adhesive surface 20b second adhesive surface 30 decorative film 30a first surface 30b second surface 40 coloring layer 50 coloring layer 60 second adhesive layer 60a first adhesive surface 60b second adhesive surface

Claims

1. A laminate in which a transparent component, an adhesive layer, and a decorative film are arranged in this order, The decorative film comprises a base layer and a decorative layer that covers at least a portion of the surface of the base layer on the adhesive layer side, and has a decorative surface on the adhesive layer side. The laminated body is The first adhesive surface of the adhesive layer is adhered to the adhesive layer side surface of the transparent member, and the second adhesive surface of the adhesive layer is in contact with and adhered to the decorative surface of the decorative film, at least a portion of which is the decorative layer. The decorative layer is a continuous or discontinuous inorganic layer. The total light transmittance of the adhesive layer is 85% or more. The aforementioned transparent member is made of glass. The thickness of the transparent member is 0.5 mm or more and 1.0 mm or less. A laminate in which the thickness of the adhesive layer is 1 μm to 500 μm.

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

3. The laminate according to claim 1 or 2, wherein the haze value of the adhesive layer is 1% or less.

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

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

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

7. The laminate according to any one of claims 1 to 6, wherein the adhesive layer has an elastic modulus of 3.0 MPa or more as measured by the following tensile test. [Tensile Test] The adhesive layer is exposed to an illuminance of 300 mW / cm². ２ , cumulative light intensity 3000 mJ / cm ２ The adhesive layer is irradiated with ultraviolet light under the specified conditions and aged at 50°C for 48 hours. After this, the adhesive layer is cut to a size of 10 mm in width and 150 mm in length to prepare a test specimen. In an environment of 23°C and 50% RH, a tensile test is performed on the test specimen using a tensile testing machine with a chuck distance of 120 mm and a tensile speed of 50 mm / min to obtain a stress-displacement curve, and the modulus of elasticity [MPa] is calculated from its initial slope.

8. The aforementioned 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. For the measurement sample, the first surface of a 10 mm square adhesive layer is bonded to the center of a 25 mm square, 1.7 mm thick chemically strengthened glass plate. Then, the second surface of the adhesive layer is bonded to the center of a 40 mm square stainless steel plate (SUS304BA plate) and pressed with a load of 5 N for 10 seconds. Subsequently, it is autoclaved (50°C, 0.5 MPa, 15 minutes), and an illuminance of 300 mW / cm² is applied from the glass plate side. ２ , cumulative light intensity 3000 mJ / cm ２ The product used will have been irradiated with ultraviolet light under these conditions, followed by aging at 50°C for 48 hours. The measurement sample is fixed with the stainless steel plate facing downwards, and the absorbed energy [J] is measured when a hammer is struck against the outer surface of the glass plate under the conditions of hammer energy 2.75 J and hammer speed 3.5 m / s in an environment of 23°C and 50% RH, thereby determining the impact resistance [J / 10mm]. ２ To find out ].

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

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

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

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

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

14. Furthermore, the laminate according to any one of claims 1 to 13, wherein a colored layer is disposed on the side of the decorative film opposite to the adhesive layer.

15. A laminate according to any one of claims 1 to 14, used in portable electronic devices.

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