Adhesive sheet, laminate for image display device, adhesive sheet roll set, and method for producing adhesive sheet with release film

Abstract

Provided is an adhesive sheet having an adhesive layer (X1) and an adhesive layer (X2) as a thick adhesive sheet, for example, a new adhesive sheet 300 μm or more thick, from the viewpoint of the ability to follow differences in level and the like, wherein both the adhesive layer (X1) and the adhesive layer (X2) include an adhesive component derived from a (meth)acrylic polymer (A), the total thickness of the adhesive sheet is 300 μm or more, the thickness of both the adhesive layer (X1) and the adhesive layer (X2) is 100 μm or more, and the ratio (x2 / x1) of the thickness (x2) of the adhesive layer (X2) and the thickness (x1) of the adhesive layer (X1) is 1-3.

Description

Adhesive sheet, laminate for image display device, adhesive sheet roll set, and method for producing adhesive sheet with release film

[0001] The present invention relates to a pressure-sensitive adhesive sheet, a laminate for an image display device using the pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet roll set having two pressure-sensitive adhesive sheet rolls with release films, and a method for producing a pressure-sensitive adhesive sheet with release films using the pressure-sensitive adhesive sheet roll set.

[0002] Glass or plastic films are laminated as surface protective layers on image display modules of electronic devices such as mobile terminals, computer displays, and touch panels. These surface protective layers are fixed to the image display module or touch panel by applying a frame-shaped tape or adhesive to the outer margin of the image display area or the outside of the effective operating area of ​​the touch panel. As a result, a gap is formed between the image display area or the effective operating area of ​​the touch panel and the surface protective layer.

[0003] A trend in the industry is to replace the gap between the image display module or touch panel and the surface protection layer with a transparent material that roughly matches the refractive index of these materials to improve transparency and image clarity. Examples of transparent materials used in this case include pressure-sensitive adhesives, adhesives, silicone gels, etc. When adhesives are used as the transparent material, there is a problem that, for example, after bonding the surface protection layer to the image display module, it is difficult to peel off and replace the surface protection layer if a defect occurs. Furthermore, when silicone gel is used, there is a problem with long-term reliability due to low adhesive strength. In contrast, pressure-sensitive adhesives, especially adhesive sheets, have sufficient adhesive strength and are reusable, making them effective for bonding the surface protection layer to the image display module or touch panel.

[0004] The surfaces of adherends such as image display modules, optical components, and surface protective layers are often uneven. The surface of the surface protective layer, particularly the surface that comes into contact with the adhesive sheet, is often printed for decorative or light-shielding purposes. In some cases, the printed portion creates a step of 10 μm or more on the surface of the surface protective layer. When an image display module or touch panel is bonded to the surface protective layer using an adhesive sheet, there is a problem that, for example, the adhesive sheet does not conform to the step insufficiently, resulting in voids on or near the step. Furthermore, the stress caused by deformation of the adhesive sheet is too great, which may result in color unevenness on the liquid crystal display. To avoid these problems, the thickness of the adhesive sheet usually needs to be approximately 10 times the height of the step.

[0005] From this viewpoint, i.e., from the viewpoint of conformability to unevenness, a thick adhesive sheet, for example, an adhesive sheet of 300 μm or more, may be required. Regarding thick adhesive sheets, for example, Patent Document 1 discloses an adhesive sheet of 0.05 to 2 mm, specifically an adhesive sheet of 500 μm.

[0006] Furthermore, with regard to release film-attached pressure-sensitive adhesive sheets having a layer structure of release film / pressure-sensitive adhesive sheet / release film, double-sided pressure-sensitive adhesive sheets with a laminated structure in which a light release film with a relatively low release strength and a heavy release film with a relatively high release strength are laminated on both sides of the pressure-sensitive adhesive layer have been known (e.g., Patent Documents 2 and 3). An example of a processing step for such a double-sided pressure-sensitive adhesive sheet with a laminated structure is to first peel off the light release film, and then adhere one surface of the exposed pressure-sensitive adhesive layer to the surface of the other object to be bonded, and after this adhesion, further peel off the heavy release film, and then adhere the other surface of the exposed pressure-sensitive adhesive layer to the surface of a different object, thereby surface-bonding the objects.

[0007] JP 2003-336013 A JP 2016-180021 A JP 2016-188266 A

[0008] As mentioned above, from the viewpoint of conformability to unevenness, a thick adhesive sheet, for example, an adhesive sheet having a thickness of 300 μm or more, may be required. However, if the thickness of the adhesive sheet is too thick, specifically if the thickness is 300 μm or more, it may be difficult to form the adhesive sheet into a uniform sheet, or it may be difficult to roll it into a roll for storage or transportation, or even if it can be rolled up once, there may be problems such as a risk of poor appearance when stored in a rolled state for a certain period of time or when unwound. Furthermore, when trying to thicken an adhesive sheet by laminating two adhesive sheets together, for example, when two identical release film-attached adhesive sheets having a layer structure of release film / adhesive sheet / release film are used to laminate the two adhesive sheets together, it is expected that the peel strength of the release films on both sides will be relatively the same, making it difficult to peel off the release films.

[0009] Therefore, an object of the present invention is to provide a thick adhesive sheet, for example a new adhesive sheet having a thickness of 300 μm or more, from the viewpoint of conformability to unevenness, etc., and a laminate for an image display device using the same. Another object of the present invention is to provide a new production method for a release film-attached adhesive sheet comprising such a thick adhesive sheet, which can produce an adhesive sheet with a release film that can form a uniform sheet shape, has good storage stability, and from which the release films on both sides can be easily peeled, and an adhesive sheet roll set to be used therefor.

[0010] The pressure-sensitive adhesive sheet proposed by the present invention, the laminate for an image display device using the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet roll set, and the method for producing a pressure-sensitive adhesive sheet with a release film using the pressure-sensitive adhesive sheet roll set have the following configurations in order to solve the above-mentioned problems.

[0011] [1] A first aspect of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (X1) and a pressure-sensitive adhesive layer (X2), wherein both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) contain a pressure-sensitive adhesive component derived from a (meth)acrylic polymer (A), the total thickness of the pressure-sensitive adhesive sheet is 300 μm or more, the thicknesses of the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) are both 100 μm or more, and the ratio (x2 / x1) of the thickness (x2) of the pressure-sensitive adhesive layer (X2) to the thickness (x1) of the pressure-sensitive adhesive layer (X1) is 1 to 3 (also referred to as the "pressure-sensitive adhesive sheet of the present invention").

[0012] [2] A second aspect of the present invention is a pressure-sensitive adhesive sheet according to the first aspect, wherein an interface between the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) is observed when a cross section of the pressure-sensitive adhesive sheet according to the first aspect is observed with an electron microscope. [3] A third aspect of the present invention is a pressure-sensitive adhesive sheet according to the first or second aspect, wherein the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) both have a storage modulus G' at a temperature of 25°C of 1 kPa or more and 1,000 kPa or less. [4] A fourth aspect of the present invention is a pressure-sensitive adhesive sheet according to any one of the first to third aspects, wherein the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) both have a storage modulus G' at a temperature of 60°C of 0.1 kPa or more and 200 kPa or less. [5] A fifth aspect of the present invention is the pressure-sensitive adhesive sheet according to any one of the first to fourth aspects, wherein the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) each have a glass transition temperature (Tg) of −50° C. or higher and 5° C. or lower.

[0013] [6] A sixth aspect of the present invention is a laminate for an image display device, which has a configuration in which two optical members are laminated via the adhesive sheet of any one of the first to fifth aspects, and the optical members have a size of 10 inches or more and 100 inches or less.

[0014] [7] A seventh aspect of the present invention is a pressure-sensitive adhesive sheet roll set comprising a pressure-sensitive adhesive sheet roll (Z1) with a release film having a layer structure of release film (Y1) / adhesive layer (X1) / release film (Y3), and a pressure-sensitive adhesive sheet roll (Z2) with a release film having a layer structure of release film (Y2) / adhesive layer (X2) / release film (Y4), wherein the peel strength (α1) between the release film (Y1) and the adhesive layer (X1) is greater than the peel strength (α3) between the release film (Y3) and the adhesive layer (X1), the peel strength (α2) between the release film (Y2) and the adhesive layer (X2) is greater than the peel strength (α4) between the release film (Y4) and the adhesive layer (X2), The pressure-sensitive adhesive sheet roll set has a peel strength ratio (α1 / α2) of 1.1 or more between the peel strength (α1) of the release film (Y1) / adhesive layer (X1) and the peel strength (α2) of the release film (Y2) / adhesive layer (X2).

[0015] [8] An eighth aspect of the present invention is a pressure-sensitive adhesive sheet roll set according to the seventh aspect, wherein both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) contain a pressure-sensitive adhesive component derived from the (meth)acrylic polymer (A). [9] A ninth aspect of the present invention is a pressure-sensitive adhesive sheet roll set according to the seventh or eighth aspect, wherein both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) have a thickness of 100 μm or more.

[10] A tenth aspect of the present invention is a pressure-sensitive adhesive sheet roll set according to any one of the seventh to ninth aspects, wherein both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) have a storage modulus G' at a temperature of 25° C. of 1 kPa or more and 1,000 kPa or less.

[11] An eleventh aspect of the present invention is the pressure-sensitive adhesive sheet roll set according to any one of the seventh to tenth aspects, wherein the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) both have a storage modulus G' of 0.1 kPa or more and 200 kPa or less at a temperature of 60° C.

[12] A twelfth aspect of the present invention is the pressure-sensitive adhesive sheet roll set according to any one of the seventh to eleventh aspects, wherein the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) both have a glass transition temperature (Tg) of -50° C. or more and 5° C. or less.

[0016]

[13] A thirteenth aspect of the present invention provides a sheet roll body (Z1) made of a pressure-sensitive adhesive sheet with a release film, which has a layer structure of release film (Y1) / adhesive layer (X1) / release film (Y3), and in which the peel strength (α1) between the release film (Y1) and the adhesive layer (X1) is greater than the peel strength (α3) between the release film (Y3) and the adhesive layer (X1), and a sheet roll body (Z2) made of a pressure-sensitive adhesive sheet with a release film, which has a layer structure of release film (Y2) / adhesive layer (X2) / release film (Y4), and in which the peel strength (α2) between the release film (Y2) and the adhesive layer (X2) is greater than the peel strength (α4) between the release film (Y4) and the adhesive layer (X2), The method for producing a pressure-sensitive adhesive sheet with a release film includes unwinding the sheet roll body (Z1), peeling the release film (Y3) to form a release film (Y1) / adhesive layer (X1), and bonding together an adhesive surface of the adhesive layer (X1) obtained by unwinding the sheet roll body (Z2), and peeling the release film (Y4) to form a release film (Y2) / adhesive layer (X2), to form a pressure-sensitive adhesive sheet with a release film having a layer structure of release film (Y1) / adhesive layer (X1) / adhesive layer (X2) / release film (Y2).

[0017]

[14] A fourteenth aspect of the present invention is the method for producing a pressure-sensitive adhesive sheet with a release film, wherein in the thirteenth aspect, the peel strength ratio (α1 / α2) of the peel strength (α1) of the release film (Y1) / adhesive layer (X1) to the peel strength (α2) of the release film (Y2) / adhesive layer (X2) is 1.1 or more.

[0018] The pressure-sensitive adhesive sheet proposed by the present invention (pressure-sensitive adhesive sheet of the present invention) has a total thickness of 300 μm or more, and therefore can have good conformability to large unevenness. Furthermore, according to the method for producing a pressure-sensitive adhesive sheet with a release film proposed by the present invention, for example, two or more pressure-sensitive adhesive layers (X1) and (X2) each having a thickness of 100 μm or more can be separately prepared and then bonded together to form a pressure-sensitive adhesive sheet of the present invention having an interface. This allows each pressure-sensitive adhesive layer (X1) and (X2) to be uniform, and the sheet can be made into a roll suitable for storage and transportation, thereby improving storage stability. Furthermore, the peel strength (α1) between the release film (Y1) and the pressure-sensitive adhesive layer (X1) is greater than the peel strength (α2) between the release film (Y2) and the pressure-sensitive adhesive layer (X2), allowing the release films on both sides to be easily peeled off.

[0019] An example of an embodiment of the present invention will be described below, but the present invention is not limited to the embodiment described below.

[0020] <Adhesive Sheet of the Present Invention> A pressure-sensitive adhesive sheet according to one embodiment of the present invention (referred to as "adhesive sheet of the present invention") is a pressure-sensitive adhesive sheet having an adhesive layer (X1) and an adhesive layer (X2).

[0021] The total thickness of the pressure-sensitive adhesive sheet of the present invention is preferably 300 μm or more, more preferably 350 μm or more, even more preferably 400 μm or more, and even more preferably 450 μm or more, from the viewpoint of conformability to large steps as described above. The upper limit is not particularly limited, but from the viewpoint of suppressing the thickness of an image display device, for example, when the pressure-sensitive adhesive sheet of the present invention is used to manufacture the image display device, it is preferably 2000 μm or less, and even more preferably 1000 μm or less.

[0022] When the cross section of the pressure-sensitive adhesive sheet of the present invention is observed using an electron microscope, it is preferable that the interface between the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) can be observed. That is, when the cross section of the pressure-sensitive adhesive sheet of the present invention is observed using an electron microscope, it is preferable that at least one interface extending parallel to the sheet surface can be observed. Note that the pressure-sensitive adhesive sheet of the present invention may be any pressure-sensitive adhesive sheet having the above-mentioned interface, and for example, a desired interface can be formed by laminating pressure-sensitive adhesive sheets together. On the other hand, when the same material is laminated by extrusion molding, the interface between the layers cannot be observed, so this is different from this.

[0023] The thickness of each of the adhesive layers (X1) and (X2) is preferably 100 μm or more. If the thickness of each of the adhesive layers (X1) and (X2) is 100 μm or more, the total thickness of the adhesive sheet of the present invention can be increased, so the thickness of each of the adhesive layers (X1) and (X2) is preferably 100 μm or more, more preferably 150 μm or more, and even more preferably 200 μm or more. On the other hand, if each thickness is too thick, as mentioned above, problems such as difficulty in winding into a roll for storage or transportation and poor appearance when unwound arise. Therefore, the thickness of each of the adhesive layers (X1) and (X2) is preferably 300 μm or less, even more preferably 250 μm or less, and even more preferably 200 μm or less.

[0024] The thicknesses of the adhesive layer (X1) and the adhesive layer (X2) may be the same or different, and the ratio (x2 / x1) of the thickness (x2) of the adhesive layer (X2) to the thickness (x1) of the adhesive layer (X1) is preferably 1 to 3. If the ratio (x2 / x1) is 3 or less, the number of adhesive layers can be reduced, that is, the lamination interface of the adhesive layers can be reduced, and the thickness of the adhesive sheet can be increased, which is preferable. From this viewpoint, the ratio (x2 / x1) is preferably 3 or less, more preferably 2 or less, and even more preferably 1.5 or less.

[0025] It is preferable that both the adhesive layer (X1) and the adhesive layer (X2) contain a pressure-sensitive adhesive component derived from the (meth)acrylic polymer (A). If both the adhesive layer (X1) and the adhesive layer (X2) contain a pressure-sensitive adhesive component derived from the (meth)acrylic polymer (A), sufficient adhesive strength can be obtained, which is preferable. Note that the "pressure-sensitive adhesive component derived from the (meth)acrylic polymer (A)" means a pressure-sensitive adhesive component made from the (meth)acrylic polymer (A) as a raw material, and includes at least the (meth)acrylic polymer (A) or a reaction product of the (meth)acrylic polymer (A), for example, a crosslinked product obtained by crosslinking the (meth)acrylic polymer (A).

[0026] The preferred compositions of the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) are the same as the compositions of the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet with a release film of the present invention described below.

[0027] The adhesive layer (X1) and the adhesive layer (X2) in the pressure-sensitive adhesive sheet of the present invention are preferably configured by laminating two layers together. An example of the pressure-sensitive adhesive sheet of the present invention includes an adhesive layer (X1) and an adhesive layer (X2) on the front and back sides, and the thickness of the adhesive layer (X1) and the thickness of the adhesive layer (X2) are each 100 μm or more. In this case, the pressure-sensitive adhesive sheet of the present invention may have a two-layer configuration consisting of the adhesive layer (X1) and the adhesive layer (X2), or a multi-layer configuration of three or more layers with one or more intermediate layers between the adhesive layer (X1) and the adhesive layer (X2). The thicknesses of the adhesive layer (X1) and the adhesive layer (X2) may be the same or different, and may be 200 μm or more as long as they are 100 μm or more. On the other hand, if each thickness is too thick, as mentioned above, it becomes difficult to form a uniform sheet, making it difficult to wind it into a roll for storage or transportation, and causing problems such as poor appearance when unwound.From this viewpoint, the thickness is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less.

[0028] [Storage Modulus (G')] The adhesive layer (X1) and adhesive layer (X2) in the adhesive sheet of the present invention, i.e., the adhesive layer (X1) and adhesive layer (X2) in a laminated state, each preferably have a storage modulus (G') at a temperature of 25 ° C. of 1 kPa or more, more preferably 10 kPa or more, and even more preferably 20 kPa or more, from the viewpoint of imparting adhesive strength and reliability when made of a solvent-free system. On the other hand, from the viewpoint of improving conformability to uneven surfaces when made of a solvent-free system, each preferably have a storage modulus (G') of 1000 kPa or less, more preferably 500 kPa or less, even more preferably 200 kPa or less, and even more preferably 100 kPa or less. From the same viewpoint as above, the storage modulus (G') at 60 ° C. of each of the adhesive layers (X1) and (X2) in a laminated state is preferably 0.1 kPa or more, more preferably 1 kPa or more, and even more preferably 5 kPa or more. On the other hand, each is preferably 200 kPa or less, particularly 100 kPa or less, particularly 60 kPa or less, and particularly 30 kPa or less. In order to adjust the storage modulus (G') of the adhesive layer (X1) and adhesive layer (X2) in the pressure-sensitive adhesive sheet of the present invention at temperatures of 25°C and 60°C to within the above range, the composition, molecular weight or glass transition temperature (Tg) of the main component resin (base polymer) of the adhesive layer (X1) and adhesive layer (X2) may be adjusted, or the compounding ratio of the crosslinking agent and initiator used when producing the adhesive layer (X1) and adhesive layer (X2) may be adjusted. However, this is not limited to this.

[0029] [Glass transition temperature (Tg)] The adhesive layer (X1) and adhesive layer (X2) in the pressure-sensitive adhesive sheet of the present invention, i.e., the adhesive layer (X1) and adhesive layer (X2) in a laminated state, each preferably have a glass transition temperature (Tg) of −50° C. or higher, more preferably −40° C. or higher, and even more preferably −30° C. or higher, from the viewpoint of enhancing adhesive strength when made of a solvent-free system. On the other hand, from the viewpoint of enhancing conformability to uneven surfaces when made of a solvent-free system, each preferably has a glass transition temperature (Tg) of 5° C. or lower, more preferably 0° C. or lower, even more preferably −10° C. or lower, and even more preferably −20° C. or lower. The glass transition temperatures (Tg) of the adhesive layer (X1) and adhesive layer (X2) in the pressure-sensitive adhesive sheet of the present invention can be adjusted to fall within the above range by adjusting the composition, molecular weight, or glass transition temperature (Tg) of the main component resin (base polymer) of the adhesive layer (X1) and adhesive layer (X2), or by adjusting the compounding ratio of the crosslinking agent and initiator used when preparing the adhesive layer (X1) and adhesive layer (X2). The glass transition temperature (Tg) of the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) in the pressure-sensitive adhesive sheet of the present invention is a glass transition temperature (Tg) defined as the peak temperature of the loss tangent (Tanδ) obtained by dynamic viscoelasticity measurement.

[0030] [Gel Fraction] The adhesive layer (X1) and adhesive layer (X2) in the pressure-sensitive adhesive sheet of the present invention, i.e., the adhesive layer (X1) and adhesive layer (X2) in a laminated state, each preferably have a gel fraction of 40% or more, more preferably 50% or more, and even more preferably 60% or more. On the other hand, from the viewpoint of improving conformability to uneven surfaces during lamination, each preferably has a gel fraction of 80% or less, more preferably 75% or less, and even more preferably 70% or less. To adjust the gel fractions of the adhesive layer (X1) and adhesive layer (X2) in the pressure-sensitive adhesive sheet of the present invention to fall within the above range, the type and amount of crosslinking agent and initiator, and the amount of UV irradiation may be adjusted. However, this is not limiting.

[0031] The pressure-sensitive adhesive sheet of the present invention can be provided and used as a pressure-sensitive adhesive sheet alone, or can be provided as a pressure-sensitive adhesive sheet with a release film of the present invention described below, and used by peeling off the release film.In addition, the pressure-sensitive adhesive sheet of the present invention can be provided in a state where it is attached to one or both sides of an adherend, such as an optical member.

[0032] <Adhesive Sheet with Release Film of the Present Invention> A release film-attached adhesive sheet according to one embodiment of the present invention (referred to as "adhesive sheet with release film of the present invention") is an adhesive sheet with a release film having a layer structure of release film (Y1) / adhesive sheet of the present invention / release film (Y2), for example a layer structure of release film (Y1) / adhesive layer (X1) / adhesive layer (X2) / release film (Y2). In the present invention, when it is expressed as "release film (Y1) / adhesive sheet of the present invention / release film (Y2)", it indicates a layer structure in which the release film (Y1), adhesive sheet of the present invention and release film (Y2) are laminated in this order. The same applies to other cases.

[0033] The peel strength ratio (α1 / α2) of the release film (Y1) / adhesive layer (X1) peel strength (α1) to the release film (Y2) / adhesive layer (X2) peel strength (α2) is preferably 1.1 or more, more preferably 1.3 or more, even more preferably 1.5 or more, even more preferably 1.8 or more, even more preferably 2.0 or more, and even more preferably 2.3 or more, from the viewpoint of ease of peeling of the release film (Y2). On the other hand, from the viewpoint of ease of peeling of the release film (Y2), it is preferably 20 or less, even more preferably 10 or less, even more preferably 6 or less, and even more preferably 3 or less.

[0034] The peel force (α1) is preferably 0.02 N / cm or more, particularly 0.05 N / cm or more, and even more preferably 0.08 N / cm or more, from the viewpoint of workability when peeling off the release film (Y1) or preventing peeling of the release film during roll storage. On the other hand, from the viewpoint of ease of peeling off the release film (Y1) after lamination to the adherend, it is preferably 0.40 N / cm or less, particularly 0.30 N / cm or less, and even more preferably 0.20 N / cm or less. The peel force (α2) is preferably 0.02 N / cm or more, particularly 0.04 N / cm or more, and even more preferably 0.18 N / cm or more, from the viewpoint of workability when peeling off the release film (Y2) or preventing peeling of the release film during roll storage. On the other hand, from the viewpoint of ease of peeling of the release film (Y2), it is preferably 0.40 N / cm or less, particularly preferably 0.25 N / cm or less, and even more preferably 0.18 N / cm or less.

[0035] In the present invention, a release film with a relatively high peeling strength is sometimes referred to as a "heavy release film" or "heavy separator," and a release film with a relatively low peeling strength is sometimes referred to as a "light release film" or "light separator."

[0036] Regarding the means for adjusting the peel force (α1) between the release film (Y1) and the adhesive layer (X1) and the peel force (α2) between the release film (Y2) and the adhesive layer (X2), for example, in the case of a configuration in which a release layer is laminated on a base film, the peel force can be adjusted by the composition and thickness of the release layer, the thickness of the base film, etc. However, since release films with various peel strengths are currently commercially available, the peel force (α1) and the peel force (α2) can be adjusted by appropriately purchasing and using a release film with the desired peel strength. The method for adjusting the peel force between the release film and the adhesive sheet is the same in other cases.

[0037] An example of the pressure-sensitive adhesive sheet with a release film of the present invention is a pressure-sensitive adhesive sheet with a release film having a layer structure of release film (Y1) / adhesive layer (X1) / adhesive layer (X2) / release film (Y2), wherein the adhesive layer (X1) is a pressure-sensitive adhesive sheet with a release film having a layer structure of release film (Y1) / adhesive layer (X1) / release film (Y3), and the peel strength (α1) between the release film (Y1) and the adhesive layer (X1) is greater than the peel strength (α3) between the release film (Y3) and the adhesive layer (X1), The adhesive layer (X2) is an adhesive sheet with a release film having a layer structure of release film (Y4) / adhesive layer (X2) / release film (Y2), and is an adhesive layer formed from an adhesive sheet with a release film in which the peel strength (α2) between the release film (Y2) and the adhesive layer (X2) is greater than the peel strength (α4) between the release film (Y4) and the adhesive layer (X2), and, as mentioned above, examples include those in which the peel strength (α1) between the release film (Y1) and the adhesive layer (X1) is greater than the peel strength (α2) between the release film (Y2) and the adhesive layer (X2).

[0038] In the case of the above-mentioned configuration, the adhesive layer (X1) is formed by peeling off the release film (Y3), which is a light separator, from the layer configuration of release film (Y1) / adhesive layer (X1) / release film (Y3), to form a configuration of release film (Y1) / adhesive layer (X1); while the adhesive layer (X2) is formed by peeling off the release film (Y4), which is a light separator, from the layer configuration of release film (Y4) / adhesive layer (X2) / release film (Y2), to form a configuration of release film (Y2) / adhesive layer (X2); and the adhesive surface of the adhesive layer (X1) in the configuration of release film (Y1) / adhesive layer (X1) and the adhesive surface of the adhesive layer (X2) in the configuration of release film (Y2) / adhesive layer (X2) are bonded together to form a configuration of release film (Y1) / adhesive layer (X1)+adhesive layer (X2) / release film (Y2). Alternatively, the adhesive surface of the adhesive layer (X1) in the release film (Y1) / adhesive layer (X1) configuration and the adhesive surface of the adhesive layer (X2) in the release film (Y2) / adhesive layer (X2) configuration can be bonded to an intermediate adhesive layer to form a structure of release film (Y1) / adhesive layer (X1) + intermediate adhesive layer + adhesive layer (X2) / release film (Y2).

[0039] In this case, the peel strength ratio (α1 / α2) of the release film (Y1) / adhesive layer (X1) peel strength (α1) to the release film (Y2) / adhesive layer (X2) peel strength (α2) is preferably 1.1 or more from the viewpoint of ease of peeling of the release film (Y1) and the release film (Y2), and more preferably 1.3 or more, more preferably 1.5 or more, more preferably 1.8 or more, more preferably 2.0 or more, and even more preferably 2.3 or more. On the other hand, from the viewpoint of ease of peeling of the release film (Y2), it is preferably 20 or less, more preferably 10 or less, more preferably 6 or less, and even more preferably 3 or less.

[0040] From the viewpoint of ease of peeling of each release film, the peel force ratio (α1 / α3) between the peel force (α1) and the peel force (α3) and the peel force ratio (α2 / α4) between the peel force (α2) and the peel force (α4) are preferably 1.1 or more, more preferably 1.3 or more, even more preferably 1.5 or more, even more preferably 1.8 or more, even more preferably 2.0 or more, and even more preferably 2.3 or more. On the other hand, from the viewpoint of ease of peeling of the release film (Y2), they are preferably 20 or less, even more preferably 10 or less, even more preferably 6 or less, and even more preferably 3 or less.

[0041] From the viewpoint of storage stability in a roll form or handling properties when peeling off the release film, the peel force (α1) is preferably 0.02 to 0.40 N / cm, and more preferably 0.05 N / cm or more or 0.30 N / cm or less, and even more preferably 0.08 N / cm or more or 0.20 N / cm or less. From the viewpoint of storage stability in a roll form or handling properties when peeling off the release film, the peel force (α3) is preferably 0.01 to 0.20 N / cm, and even more preferably 0.02 N / cm or more or 0.15 N / cm or less, and even more preferably 0.03 N / cm or more or 0.10 N / cm or less.

[0042] From the viewpoint of storage stability in a roll form or handling properties when peeling off the release film, the peel force (α2) is preferably 0.02 N / cm or more or 0.40 N / cm or less, and more preferably 0.04 N / cm or more or 0.25 N / cm or less, and even more preferably 0.06 N / cm or more or 0.18 N / cm or less. From the viewpoint of storage stability in a roll form or handling properties when peeling off the release film, the peel force (α4) is preferably 0.01 to 0.20 N / cm, and even more preferably 0.02 N / cm or more or 0.15 N / cm or less, and even more preferably 0.03 N / cm or more or 0.10 N / cm or less.

[0043] [Storage Modulus (G')] When the adhesive layer (X1) and adhesive layer (X2) in the adhesive sheet with release film of the present invention are solvent-free, from the viewpoint of imparting adhesive strength and reliability, the storage modulus (G') at a temperature of 25 ° C. is preferably 1 kPa or more, more preferably 10 kPa or more, and even more preferably 20 kPa or more. On the other hand, when the adhesive layer (X1) and adhesive layer (X2) are solvent-free, from the viewpoint of improving conformability to uneven surfaces, the storage modulus (G') is preferably 1000 kPa or less, more preferably 500 kPa or less, even more preferably 200 kPa or less, and even more preferably 100 kPa or less. From the same viewpoint as above, the storage modulus (G') at 60 ° C. is preferably 0.1 kPa or more, more preferably 1 kPa or more, and even more preferably 5 kPa or more. On the other hand, it is preferably 200 kPa or less, particularly 100 kPa or less, particularly 60 kPa or less, and particularly 30 kPa or less. In order to adjust the storage modulus (G') of the adhesive layer (X1) and the adhesive layer (X2) at a temperature of 25°C or 60°C to fall within the above range, the composition, molecular weight or Tg of the main component resin (base polymer) may be adjusted, or the compounding ratio of the crosslinking agent or initiator may be adjusted. However, this is not limitative.

[0044] [Glass Transition Temperature (Tg)] In order to enhance adhesive strength when the adhesive layer (X1) and adhesive layer (X2) in the release film-attached adhesive sheet of the present invention are solvent-free, the glass transition temperature (Tg) is preferably −50° C. or higher, more preferably −40° C. or higher, and even more preferably −30° C. or higher. On the other hand, in order to enhance conformability to uneven surfaces when the adhesive layer is solvent-free, the glass transition temperature (Tg) is preferably 5° C. or lower, more preferably 0° C. or lower, even more preferably −10° C. or lower, and even more preferably −20° C. or lower. The glass transition temperatures (Tg) of the adhesive layer (X1) and adhesive layer (X2) can be adjusted to fall within the above range by adjusting the composition, molecular weight, or Tg of the main component resin (base polymer), or by adjusting the compounding ratio of the crosslinking agent and initiator. However, the present invention is not limited to this. The glass transition temperature (Tg) of the adhesive layer (X1) and the adhesive layer (X2) is a glass transition temperature (Tg) defined as the peak temperature of the loss tangent (Tan δ) obtained by dynamic viscoelasticity measurement.

[0045] [Gel Fraction] In the pressure-sensitive adhesive sheet with release film of the present invention, the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) preferably have a gel fraction of 40% or more, more preferably 50% or more, and even more preferably 60% or more, from the viewpoint of improving reliability after lamination. On the other hand, in the viewpoint of improving conformability to irregularities during lamination, the gel fraction is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less.

[0046] (Composition) The adhesive layer (X1) and the adhesive layer (X2) may have any composition as long as they have adhesive strength. If necessary, they may be capable of being adhered by applying pressure or heat. Furthermore, the adhesive layer (X1) and the adhesive layer (X2) may have the same composition or different compositions. The adhesive layer (X1) and the adhesive layer (X2) are collectively referred to as "the adhesive sheet."

[0047] The adhesive layer (X1) and the adhesive layer (X2) may be a pressure-sensitive adhesive sheet, a heat-curable adhesive sheet, or an ultraviolet-curable adhesive sheet. Among them, from the viewpoint of the simplicity of the curing process and the stability of the physical properties after curing, a solvent-free adhesive sheet formed from a resin composition containing no solvent and an ultraviolet-curable adhesive sheet is preferred. For example, an ultraviolet-curable adhesive sheet that is primarily cured to obtain sheet retention and adhesiveness, i.e., an ultraviolet-curable adhesive sheet that is provisionally cured so as to leave room for final ultraviolet curing, can be mentioned.

[0048] (Main Component Resin) The main component resins of the adhesive layer (X1) and the adhesive layer (X2) may be the same or different. It is preferable that both the adhesive layer (X1) and the adhesive layer (X2) contain a (meth)acrylic polymer as the main component resin. However, as described above, the (meth)acrylic polymer that is the main component resin of the adhesive layer (X1) and the adhesive layer (X2) is preferably derived from the (meth)acrylic polymer (A). Here, the term "main component resin" refers to the resin with the highest mass percentage among the resins constituting each layer. The content of the main component resin is not particularly limited, but it can be assumed that the main component resin accounts for, for example, 50 mass% or more, particularly 60 mass% or more, particularly 70 mass% or more, particularly 80 mass% or more, particularly 90 mass% or more, particularly 95 mass% or more, or particularly 100 mass% of the resin (100 mass%) constituting the adhesive layer (X1) or the adhesive layer (X2). In the present invention, the term "resin" refers to a polymer, or in other words, a polymer (including a copolymer), and includes polymers and oligomers. The molecular weight of the resin is, for example, a mass average molecular weight of 10,000 or more, preferably 50,000 or more, and more preferably 100,000 or more.

[0049] [(Meth)acrylic polymer (A)] The (meth)acrylic polymer (A) as the main component resin (base polymer) of the adhesive layer (X1) and the adhesive layer (X2) preferably has a mass average molecular weight of 100,000 to 1,000,000, from the viewpoint of easily achieving both handleability during coating and adhesive properties when it is a solvent-free system, and more preferably 200,000 or more or 800,000 or less, and even more preferably 300,000 or more or 600,000 or less. The glass transition temperature (Tg) of the (meth)acrylic polymer (A) is preferably -50 to 5°C, from the viewpoint of a balance between conformability to uneven surfaces and adhesive properties, and even more preferably -40°C or more or 0°C or less, even more preferably -35°C or more or -10°C or less, and even more preferably -30°C or more or -20°C or less.

[0050] In the present invention, the term "(meth)acrylic polymer" encompasses acrylic homopolymers, methacrylic homopolymers, acrylic copolymers, and methacrylic copolymers, the term "(meth)acrylate" encompasses acrylates and methacrylates, and the term "(meth)acryloyl" encompasses acryloyl and methacryloyl.

[0051] The (meth)acrylic polymer (A) preferably does not substantially contain, as a copolymerization component, a structural unit derived from a carboxy group-containing (meth)acrylate monomer, and contains, as monomer components constituting the copolymer, a low-Tg (meth)acrylate monomer (a1) that, when formed into a homopolymer, has a glass transition temperature (Tg) of less than −30° C., and one or more polar group-containing (meth)acrylate monomers (a2) selected from the group consisting of hydroxyl group-containing (meth)acrylate monomers and nitrogen atom-containing (meth)acrylate monomers.

[0052] Here, the above phrase "substantially free of structural units derived from carboxy group-containing (meth)acrylate monomers" not only refers to a case where structural units derived from carboxy group-containing (meth)acrylate monomers are completely absent, but also refers to a case where the (meth)acrylic copolymer contains structural units derived from carboxy group-containing (meth)acrylate monomers in an amount of 0.5% by mass or less, preferably 0.1% by mass or less.

[0053] Examples of the carboxy group-containing (meth)acrylate monomer include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, citraconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0054] [Low Tg (meth)acrylate monomer (a1)] Examples of the low Tg (meth)acrylate monomer (a1) having a glass transition temperature (Tg) of less than −30° C. when forming the homopolymer include 2-ethylhexyl acrylate (Tg; −70° C.), n-butyl acrylate (Tg; −55° C.), n-octyl (meth)acrylate (Tg; −65° C.), isooctyl acrylate (Tg; −54° C.), nonyl acrylate (Tg; −37° C.), and isononyl acrylate (Tg; − Examples of suitable copolymers include isodecyl acrylate (Tg; -58°C), isodecyl acrylate (Tg; -60°C), isodecyl methacrylate (Tg; -41°C), tridecyl acrylate (Tg; -55°C), tridecyl methacrylate (Tg; -40°C), n-lauryl methacrylate (Tg; -65°C), 2-ethoxyethyl methacrylate (Tg; -31°C), and ethoxyethoxyethyl acrylate (ethyl carbitol acrylate) (Tg; -67°C). Among these, from the viewpoints of glass transition temperature and versatility of the monomer, it is preferable to include at least one selected from 2-ethylhexyl acrylate and n-butyl acrylate as the copolymerization component.

[0055] The low Tg (meth)acrylate monomer (a1) is preferably contained in an amount of 30% by mass or more, based on a total of 100% by mass of all monomer components constituting the (meth)acrylic polymer (A). In particular, from the viewpoint of adjusting the glass transition temperature when the (meth)acrylic polymer (A) is formed, the low Tg (meth)acrylate monomer (a1) is contained in an amount of 40% by mass or more and 90% by mass or less, and of these, the low Tg (meth)acrylate monomer (a1) is contained in an amount of 45% by mass or more or 80% by mass or less.

[0056] [Polar Group-Containing (Meth)acrylate Monomer (a2)] Examples of the hydroxyl group-containing (meth)acrylate monomer as the polar group-containing (meth)acrylate monomer (a2) include (meth)acrylate monomers other than (a1) above, such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0057] Furthermore, examples of the nitrogen atom-containing (meth)acrylate monomer as the polar group-containing (meth)acrylate monomer (a2) include aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, (meth)acryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hydroxy(meth)acrylamide.

[0058] Among these, from the viewpoints of imparting polarity to improve the glass transition temperature, versatility of the monomer, and adhesive properties, it is preferable to use at least one selected from 2-hydroxyethyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, and 6-hydroxyhexyl(meth)acrylate as the hydroxyl group-containing (meth)acrylate monomer. Furthermore, from the viewpoints of imparting polarity to improve the glass transition temperature, versatility of the monomer, and adhesive properties, it is preferable to use at least one selected from N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hydroxy(meth)acrylamide as the nitrogen atom-containing (meth)acrylate monomer.

[0059] The polar group-containing (meth)acrylate monomer (a2) is preferably contained in an amount of 1% by mass or more, particularly 3% by mass or more, based on a total of 100% by mass of all monomer components constituting the (meth)acrylic polymer (A). In particular, from the viewpoint of imparting polarity in order to improve the glass transition temperature and adhesive properties when copolymerized, the polar group-containing (meth)acrylate monomer (a2) is contained in an amount of 5% by mass or more and 50% by mass or less, and of these, the polar group-containing (meth)acrylate monomer (a2) is contained in an amount of 8% by mass or more or 30% by mass or less, particularly preferably 5% by mass or more and 50% by mass or less.

[0060] [Other Copolymerization Components] In addition to the above (a1) and (a2), the (meth)acrylic polymer (A) may also use, as copolymerization components constituting the copolymer, linear or branched alkyl (meth)acrylate (a3) ​​having an alkyl group with 4 to 18 carbon atoms, epoxy group-containing (meth)acrylate monomer (a4), (meth)acrylate monomer (a5) having an alkyl group with 1 to 3 carbon atoms, and the like.

[0061] Examples of the linear or branched alkyl (meth)acrylate (a3) ​​having an alkyl group of 4 to 18 carbon atoms include those other than (a1) and (a2) above, such as isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, isobornyl (meth)acrylate, etc. These may be used alone or in combination of two or more. The linear or branched alkyl (meth)acrylate (a3) ​​having an alkyl group of 4 to 18 carbon atoms is preferably contained in an amount of 3 mass% or more, based on a total of 100 mass% of all monomer components constituting the (meth)acrylic polymer (A). In particular, from the viewpoint of adjusting the glass transition temperature when copolymerized, the amount is more preferably 5 mass% or more and 50 mass% or less, and of these, the amount is particularly preferably 8 mass% or more or 30 mass% or less.

[0062] Examples of the epoxy group-containing (meth)acrylate monomer (a4) include those other than (a1) and (a2) above, such as glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. These may be used alone or in combination of two or more. The epoxy group-containing (meth)acrylate monomer (a4) is preferably contained in an amount of 1% by mass or more relative to a total of 100% by mass of all monomer components constituting the (meth)acrylic polymer (A). In particular, from the viewpoint of imparting cohesive strength and adhesive strength to the pressure-sensitive adhesive sheet, it is more preferably contained in an amount of 2% by mass or more to 30% by mass or less, and even more preferably contained in an amount of 3% by mass or more or 15% by mass or less.

[0063] Examples of the (meth)acrylate monomer (a5) having an alkyl group containing 1 to 3 carbon atoms include those other than (a1) and (a2) above, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and i-propyl (meth)acrylate. These may be used alone or in combination of two or more. The (meth)acrylate monomer (a5) having an alkyl group containing 1 to 3 carbon atoms preferably accounts for 1 mass% or more of the total 100 mass% of all monomer components constituting the (meth)acrylic polymer (A). In particular, from the viewpoint of adjusting the glass transition temperature when copolymerized, it is more preferably contained in a proportion of 3 mass% to 50 mass%, and particularly preferably contained in a proportion of 5 mass% to 30 mass%.

[0064] Among the above, the (meth)acrylic polymer (A) is particularly preferably a three- or four-component copolymer containing, as copolymerization components constituting the copolymer, the above (a1) and (a2) as well as either the above (a3) ​​and / or (a5), from the viewpoint of adjusting the glass transition temperature and polarity upon copolymerization and imparting a good balance of adhesive properties such as cohesive strength and adhesive strength. In the present invention, when the glass transition temperature (Tg) of the copolymerization components (a2) to (a5) is lower than −30° C., these are treated as low-Tg (meth)acrylate monomers (a1).

[0065] The (meth)acrylic polymer (A) may form a crosslinked structure between the copolymers, and from the viewpoint of the shape retention of the photocurable pressure-sensitive adhesive sheet of the present invention, the shear storage modulus (G') of the pressure-sensitive adhesive sheet of the present invention at a temperature of 25°C being within the above range, and the measured Tg of the pressure-sensitive adhesive sheet of the present invention being within the above range, chemical bonds may be formed between a hydroxyl group and an isocyanate group, or between an amino group and an isocyanate group.

[0066] More specifically, examples of such a method include a method in which a pressure-sensitive adhesive resin composition is used in which the (meth)acrylic polymer (A) contains a hydroxyl group-containing (meth)acrylate as a copolymerization component and further contains an isocyanate compound having an isocyanate group reactive with the hydroxyl group, and the composition is heated or cured to react the hydroxyl group on the side chain of the (meth)acrylic polymer (A) with the isocyanate group of the isocyanate compound, thereby forming a chemical bond between the functional groups; or a method in which a pressure-sensitive adhesive resin composition is used in which the (meth)acrylic polymer (A) contains an amino group-containing (meth)acrylate as a copolymerization component and, similar to the above, contains an isocyanate compound having an isocyanate group reactive with the amino group, and the composition is heated or cured to react the amino group on the side chain of the (meth)acrylic polymer (A) with the isocyanate group of the isocyanate compound, thereby forming a chemical bond.

[0067] Examples of the isocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, and triphenylmethane triisocyanate.

[0068] Furthermore, the compound having an isocyanate group may further have a radically polymerizable functional group such as a (meth)acryloyl group, such as 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, etc. In this way, when the (meth)acrylic polymer (A) has a radically polymerizable functional group, by utilizing a crosslinking reaction between the (meth)acrylic polymers (A) due to the radically polymerizable functional group, there are advantages such as an efficient increase in cohesive strength after photocuring (crosslinking) and excellent reliability, even without using a carboxy group-containing (meth)acrylate monomer or a crosslinking agent (B), and this is more preferred.

[0069] From the same viewpoint as above, the (meth)acrylic polymer (A) preferably has a photo-crosslinkable structural moiety. The photo-crosslinkable structural moiety refers to a structural moiety that can be excited by irradiation with active energy rays and cause a hydrogen abstraction reaction to generate radicals. More specifically, the photo-crosslinkable structural moiety is preferably any one or more structures selected from a benzophenone structure, a benzyl structure, an o-benzoylbenzoic acid ester structure, a thioxanthone structure, a 3-ketocoumarin structure, a 2-ethylanthraquinone structure, and a camphorquinone structure. When the (meth)acrylic polymer (A) has such a photo-crosslinkable structural moiety, the photo-crosslinkable structural moiety can efficiently cure (crosslink) the (meth)acrylic polymer (A), which has advantages such as an efficient increase in cohesive strength after photo-curing (crosslinking) and excellent reliability without using a carboxy group-containing (meth)acrylate monomer or a crosslinking agent (B).

[0070] In order for the (meth)acrylic polymer (A) to have the above-mentioned photocrosslinkable structural moiety, a (meth)acrylate monomer having a benzophenone structure may be used as a copolymerization component, such as 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone, and mixtures thereof. By using such a (meth)acrylate monomer having a photocrosslinkable structural moiety, a photocrosslinkable structural moiety can be formed in the (meth)acrylic polymer (A).

[0071] (Composition Other Than Main Component Resin) The adhesive layer (X1) and the adhesive layer (X2) can be formed from a pressure-sensitive adhesive composition containing a base resin, for example, an acrylic polymer (A), and, if necessary, a crosslinking agent (B), a photopolymerization initiator (C), a silane coupling agent (D), and further other components, such as a rust inhibitor, a tackifying resin, etc. The adhesive layer (X1) and the adhesive layer (X2) are preferably formed from a pressure-sensitive adhesive composition containing, for example, the acrylic polymer (A) and a hydrogen abstraction photopolymerization initiator as the photopolymerization initiator (C).

[0072] (Crosslinking Agent (B)) The crosslinking agent (B) is preferably a crosslinking agent having at least a double bond crosslink. Examples include crosslinking agents having at least one crosslinkable functional group selected from a (meth)acryloyl group, an epoxy group, an isocyanate group, a carboxy group, a hydroxy group, a carbodiimide group, an oxazoline group, an aziridine group, a vinyl group, an amino group, an imino group, and an amide group, and one or more of these may be used in combination. Among the above, as described above, it is particularly preferable to use an isocyanate compound as the crosslinking agent (B), particularly from the viewpoint of forming a crosslinked structure between the (meth)acrylic polymers (A).

[0073] In addition to the above, it is also preferable to use a photopolymerizable compound having a carbon-carbon double bond, particularly a polyfunctional (meth)acrylate, as the crosslinking agent (B). Here, "polyfunctional" refers to a compound having two or more crosslinkable functional groups. If necessary, the compound may have three or more, or four or more crosslinkable functional groups.

[0074] By using a polyfunctional (meth)acrylate as the crosslinking agent (B), not only can the polyfunctional (meth)acrylates chemically bond to each other to form a chemical crosslinked structure consisting of a three-dimensional network structure, but also the chain-like (meth)acrylic polymer becomes entangled in this three-dimensional network structure, restricting the movement of the polymer and forming a physical aggregation structure, i.e., a physical crosslinked structure.

[0075] Examples of the polyfunctional (meth)acrylate include polypropylene glycol dimethacrylate, 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin glucidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-Nonanediol di(meth)acrylate, tricyclodecane dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxydi(meth)acrylate, bisphenol A polypropoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane trioxyethyl (meth)acrylate, ε- Caprolactone-modified tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol Examples of the acrylic monomer include ultraviolet-curable polyfunctional (meth)acrylic monomers such as di(meth)acrylate, polyethylene glycol di(meth)acrylate, tris(acryloxyethyl)isocyanurate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, di(meth)acrylate of an ε-caprolactone adduct of hydroxypivalic acid neopentyl glycol, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate, as well as polyfunctional (meth)acrylic oligomers such as polyester(meth)acrylate, epoxy(meth)acrylate, urethane(meth)acrylate, and polyether(meth)acrylate. These may be used alone or in combination of two or more.

[0076] The amount of crosslinking agent (B) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, particularly preferably 5 parts by mass or more, and especially preferably 10 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer (A). It is more preferably 100 parts by mass or less, more preferably 50 parts by mass or less, particularly preferably 30 parts by mass or less, and especially preferably 20 parts by mass or less. The weight average molecular weight of the crosslinking agent (B) is preferably 1000 or less, more preferably 50 or more or 800 or less, and even more preferably 100 or more or 600 or less. The molecular weight per reactive functional group of the crosslinking agent (B) is preferably 300 or less, more preferably 30 or more or 250 or less, and even more preferably 60 or more or 150 or less. The Tg of the crosslinked product of the crosslinking agent alone is preferably 100°C or more, preferably 200°C or more. By setting the crosslinking agent blending amount, crosslinking agent molecular weight, molecular weight per reactive functional group of the crosslinking agent, and crosslinking agent Tg within the above ranges, it becomes easier to adjust the elastic modulus of the pressure-sensitive adhesive sheet of the present invention to a predetermined range, making it easier to impart punching processability.

[0077] (Photopolymerization initiator (C)) Preferred examples of the photopolymerization initiator (C) include compounds that generate active radical species when irradiated with light such as ultraviolet light or visible light, more specifically, light having a wavelength of 200 nm to 780 nm.

[0078] As described above, the photopolymerization initiator (C) may be either a cleavage-type photopolymerization initiator (c1) or a hydrogen-abstraction-type photopolymerization initiator (c2), and may be used either alone or in combination, or may be used alone or in combination of two or more of each. Among these, from the viewpoint of adjusting the gel fraction within a predetermined range, it is preferred to use a hydrogen-abstraction-type photopolymerization initiator (c2) as the photopolymerization initiator (C).

[0079] Examples of the cleavage-type photopolymerization initiator (c1) include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), methyl phenylglyoxylate, 2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone, methyl phenylglyoxylate ... benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)2,4,4-trimethylpentylphosphine oxide, and derivatives thereof can be given.

[0080] Examples of the hydrogen abstraction photopolymerization initiator (c2) include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(meth)acryloyloxybenzophenone, methyl 2-benzoylbenzoate, methyl benzoylformate, bis(2-phenyl-2-oxoacetate)oxybisethylene, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl)benzophenone, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, and derivatives thereof.

[0081] The amount of the photopolymerization initiator (C) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and most preferably 0.3% by mass or more, relative to the total mass of the pressure-sensitive adhesive sheet of the present invention. The upper limit is preferably 10% by mass or less, more preferably 8 parts by mass or less, preferably 6 parts by mass or less, preferably 5 parts by mass or less, and most preferably 4.5% by mass or less. The amount is preferably 0.01 to 10 parts by mass, more preferably 0.1 parts by mass or more or 7 parts by mass or less, and particularly preferably 0.5 parts by mass or more or 5 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer (A).

[0082] (Silane Coupling Agent (D)) Examples of the silane coupling agent (D) include compounds having a hydrolyzable functional group such as an alkoxy group in addition to an unsaturated group such as a vinyl group, an acryloxy group, or a methacryloxy group, an amino group, or an epoxy group, from the viewpoint of improving adhesion, particularly adhesion to glass materials. Specific examples of the silane coupling agent include N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. Among these, γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane is preferred from the viewpoint of particularly good adhesion and little discoloration such as yellowing. The silane coupling agents can be used alone or in combination of two or more.

[0083] The content of the silane coupling agent is preferably 0.01 to 2% by mass, more preferably 0.05% by mass or more or 1% by mass or less, based on the total mass of the pressure-sensitive adhesive sheet of the present invention.

[0084] (Tackifying Resin) Examples of tackifying resins include rosin-based tackifying resins, terpene-based tackifying resins, petroleum-based tackifying resins, styrene-based tackifying resins, epoxy-based tackifying resins, polyamide-based tackifying resins, elastomer-based tackifying resins, phenol-based tackifying resins, and ketone-based tackifying resins. Among these, rosin-based tackifying resins are particularly preferred, and preferred rosin-based tackifying resins are rosin ester-based resins such as rosin ester resins, disproportionated rosin ester resins, hydrogenated rosin ester resins, and polymerized rosin ester resins. The tackifying resins can be used alone or in combination of two or more.

[0085] The content of the tackifier resin is preferably 1 to 40% by mass, more preferably 3% by mass or more or 20% by mass or less, based on the total mass of the pressure-sensitive adhesive sheet.

[0086] (Other Components) The resin composition forming the adhesive layer (X1) and the adhesive layer (X2) can appropriately contain various additives such as antioxidants, light stabilizers, metal deactivators, antiaging agents, moisture absorbers, polymerization inhibitors, ultraviolet absorbers, inorganic particles, etc., as components other than those described above. However, the resin composition forming the adhesive layer (X1) and the adhesive layer (X2) is preferably a solvent-free system that does not contain a solvent, from the viewpoint of not containing residual solvent even when applied to a thick substrate, suppressing bubble generation after lamination, etc., and improving reliability.

[0087] <Manufacturing method> Next, an example of a method for manufacturing the pressure-sensitive adhesive sheet with a release film of the present invention will be described. However, the method for manufacturing the pressure-sensitive adhesive sheet with a release film of the present invention is not limited to the manufacturing method below. Here, a case where the pressure-sensitive adhesive sheet of the present invention comprises a pressure-sensitive adhesive layer (X1) and a pressure-sensitive adhesive layer (X2) will be described.

[0088] First, a sheet roll (Z1) is prepared, which consists of a pressure-sensitive adhesive sheet with a release film, which has a layer structure of release film (Y1) / adhesive layer (X1) / release film (Y3), and in which the peel strength (α1) between the release film (Y1) and the adhesive layer (X1) is greater than the peel strength (α3) between the release film (Y3) and the adhesive layer (X1), and a sheet roll (Z2) is prepared, which consists of a pressure-sensitive adhesive sheet with a release film, which has a layer structure of release film (Y2) / adhesive layer (X2) / release film (Y4), and in which the peel strength (α2) between the release film (Y2) and the adhesive layer (X2) is greater than the peel strength (α4) between the release film (Y4) and the adhesive layer (X2). Next, the sheet roll body (Z1) is unwound, and the release film (Y3), which is a light separator, is peeled off to form a release film (Y1) / adhesive layer (X1). The adhesive surface of the adhesive layer (X1) is then bonded to the adhesive surface of the adhesive layer (X2) which is obtained by unwounding the sheet roll body (Z2) and peeling off the release film (Y4), which is a light separator, to form a release film (Y2) / adhesive layer (X2). This makes it possible to obtain an adhesive sheet with a release film having a layer structure of release film (Y1) / adhesive layer (X1)+adhesive layer (X2) / release film (Y2).

[0089] Although the above-mentioned production method is for the case where the pressure-sensitive adhesive sheet of the present invention consists of a pressure-sensitive adhesive layer (X1) and a pressure-sensitive adhesive layer (X2), a pressure-sensitive adhesive sheet of the present invention having three or more layers, including a pressure-sensitive adhesive layer (X1) and a pressure-sensitive adhesive layer (X2) as front and back layers and a pressure-sensitive adhesive sheet (X3) as an intermediate layer, can be produced in the same manner. That is, by peeling off the release film, which is a light separator, from the sheet rolls (Z1) and (Z2), and peeling off the release film from each side of the pressure-sensitive adhesive sheet (X3) that forms the intermediate layer, and then bonding the adhesive surfaces of the pressure-sensitive adhesive sheets together, a pressure-sensitive adhesive sheet with a release film having a layer structure of release film (Y1) / adhesive layer (X1)+adhesive layer (X3)+adhesive layer (X2) / release film (Y2) can be produced.

[0090] The combination of the sheet roll body (Z1) and the sheet roll body (Z2) is also referred to as a pressure-sensitive adhesive sheet roll body set, and can be provided as the pressure-sensitive adhesive sheet roll body set of the present invention. That is, the pressure-sensitive adhesive sheet roll body set of the present invention is a pressure-sensitive adhesive sheet roll body set comprising a release film-attached pressure-sensitive adhesive sheet roll body (Z1) having a layer structure of release film (Y1) / adhesive layer (X1) / release film (Y3), and a release film-attached pressure-sensitive adhesive sheet roll body (Z2) having a layer structure of release film (Y2) / adhesive layer (X2) / release film (Y4), wherein the peel strength (α1) between the release film (Y1) and the adhesive layer (X1) is greater than the peel strength (α3) between the release film (Y3) and the adhesive layer (X1), the peel strength (α2) between the release film (Y2) and the adhesive layer (X2) is greater than the peel strength (α4) between the release film (Y4) and the adhesive layer (X2), The pressure-sensitive adhesive sheet roll set has a peel strength ratio (α1 / α2) of 1.1 or more between the peel strength (α1) of the release film (Y1) / adhesive layer (X1) and the peel strength (α2) of the release film (Y2) / adhesive layer (X2).

[0091] <Uses> A laminate for an image display device (referred to as "a laminate for an image display device of the present invention") can be constructed by peeling off the release films (Y1) and (Y2) from the pressure-sensitive adhesive sheet with release film of the present invention and bonding two optical members together with the pressure-sensitive adhesive sheet of the present invention. In other words, the laminate for an image display device of the present invention is a laminate for an image display device having a configuration in which two optical members are laminated via the pressure-sensitive adhesive sheet of the present invention.

[0092] Furthermore, an image display device (referred to as "the image display device of the present invention") can be constructed using the laminate for an image display device of the present invention as a constituent member. That is, the image display device of the present invention is an image display device including the laminate for an image display device of the present invention.

[0093] With regard to the laminate for an image display device of the present invention and the image display device of the present invention, examples of the image display device include image display devices such as personal computers, televisions (TVs), mobile terminals (PDAs), mobile phones, and smartphones. However, the present invention is not limited to these. Furthermore, examples of the optical member in the laminate for an image display device of the present invention include components such as liquid crystal displays (LCDs), electroluminescent displays (ELDs), plasma display panels (PDPs), cathode ray tube displays (CRTs), surface electrolytic displays (SEDs), electronic paper, transparent screens, LED diffusion plates, head-up displays, and diffusion plates for TVs. However, the present invention is not limited to these. In particular, considering the characteristic of the pressure-sensitive adhesive sheet with release film of the present invention, i.e., the ability to increase the thickness of the pressure-sensitive adhesive sheet of the present invention, specifically the ability to increase the thickness to 300 μm or more, the pressure-sensitive adhesive sheet is suitable for bonding large optical members having a screen of 10 inches or more, particularly 20 inches or more, and even 30 inches or more, but not more than 100 inches.

[0094] <Explanation of Terms, etc.> In the present invention, the term "film" includes the term "sheet", and the term "sheet" includes the term "film".

[0095] In the present invention, when it is stated that "α to β" (α and β are any numbers), it means "not less than α and not more than β" and also means "preferably greater than α" or "preferably smaller than β" unless otherwise specified. Furthermore, when it is stated that "not less than α" or "α≦" (α is any number), it means "preferably greater than α" unless otherwise specified, and when it is stated that "not more than β" or "≦β" (β is any number), it also means "preferably smaller than β" unless otherwise specified.

[0096] An example of an embodiment of the present invention will be described below, but the present invention is not limited to the embodiment described below.

[0097] <Raw Materials> = Main Agent (Main Component Resin) = ・A-1: (meth)acrylic copolymer (2-ethylhexyl acrylate (EHA) / methyl acrylate (MA) / 2-hydroxyethyl acrylate (HEA) = (mass ratio) 65 / 20 / 15, mass average molecular weight: 460,000, Tg: -24°C) ・A-2: (meth)acrylic copolymer (2-ethylhexyl acrylate (EHA) / methyl acrylate (MA) / ethyl acrylate (EA) / 2-hydroxyethyl acrylate (HEA) = (mass ratio) 46 / 14 / 26 / 14, mass average molecular weight: 230,000, Tg: -9°C) A-3: (meth)acrylic copolymer (2-ethylhexyl acrylate (EHA) / methyl acrylate (MA) / N-vinylpyrrolidone (NVP) = (mass ratio) 46 / 46 / 8, mass average molecular weight: 240,000, Tg: 0°C)

[0098] The mass average molecular weight of the (meth)acrylic copolymer was measured using a gel permeation chromatography (GPC) analyzer (apparatus name: HLC-8320GPC manufactured by Tosoh Corporation). Specifically, 4 mg of copolymer was dissolved in 12 mL of THF to prepare a measurement sample, and the molecular weight distribution curve was measured under the following conditions to determine the mass average molecular weight (Mw). Guard column: TSKguardcolumnHXL Separation column: TSKgelGMHXL (4 columns) Temperature: 40°C Injection volume: 100 μL Polystyrene equivalent Solvent: THF Flow rate: 1.0 mL / min

[0099] The glass transition temperature (Tg) of the (meth)acrylic copolymer was measured using a rheometer (DiscoveryHR2 manufactured by TA Instruments). Specifically, the dynamic viscoelasticity spectrum was measured in the temperature range of −50° C. to 80° C. under the following conditions: adhesive jig: Φ8 mm parallel plate, strain: 0.1%, frequency: 1 Hz, temperature: −50 to 80° C., and heating rate: 5° C. / min. From the obtained data, the temperature at which the loss tangent (Tan δ) reached its maximum value was read to determine Tg.

[0100] = Materials other than the base resin (main component resin) = B-1: PDP-400N (manufactured by NOF Corporation): polypropylene glycol dimethacrylate C-1: Esacure TZT (manufactured by IGM): mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone C-1: MBP (manufactured by Shinryo Corporation): 4-methacryloyloxybenzophenone D-1: KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.): 3-glycidoxypropyltrimethoxysilane

[0101] =Release film= Light separator: Release film I: MHE75: (manufactured by Mitsubishi Chemical Corporation, thickness 75 μm, PET film with silicone release layer) Heavy separator: Release film II: MRQ100: (manufactured by Mitsubishi Chemical Corporation, thickness 100 μm, PET film with silicone release layer) Heavy separator: Release film III: MRV100 (V03): (manufactured by Mitsubishi Chemical Corporation, thickness 100 μm, PET film with silicone release layer)

[0102] <Adhesive Sheet 1 with Release Film> The above raw materials were weighed and mixed in the amounts shown in Table 1 below to prepare a pressure-sensitive adhesive composition. This pressure-sensitive adhesive composition was spread in the form of a sheet on Release Film II. Next, Release Film I was laminated on the sheet-shaped pressure-sensitive adhesive composition. The integrated light intensity at a wavelength of 365 nm was 3000 mJ / cm. ２ Using a high-pressure mercury lamp, ultraviolet light was irradiated from both sides of the release films I and II through the release films I and II (1500 mJ / cm on one side). ２ ) to cure the pressure-sensitive adhesive composition, thereby obtaining a pressure-sensitive adhesive sheet 1 with release film having a layer structure of release film I / pressure-sensitive adhesive sheet (thickness 200 μm) / release film II.

[0103] <Adhesive Sheets 2 to 11 with Release Film> Adhesive sheets 2 to 11 with release film were obtained in the same manner as in Example 1, except that the type and amount of each raw material used in preparing the adhesive composition, the type of release film, the UV irradiation dose, and the thickness of the adhesive sheet were changed as shown in Table 1.

[0104] [Storage Modulus (G') and Glass Transition Temperature (Tg)] The release films were peeled from the release film-attached pressure-sensitive adhesive sheets 1 to 11, and the pressure-sensitive adhesive sheets were laminated to a thickness of 0.6 to 0.8 mm. A measurement sample was then punched out into a circle with a diameter of 8 mm. Using a rheometer (TA Instruments, "DiscoveryHR2"), the dynamic viscoelastic spectrum was measured in the temperature range of -50°C to 200°C under the following conditions: adhesive jig: Φ8 mm parallel plate, strain: 0.1%, frequency: 1 Hz, temperature: -50 to 200°C, heating rate: 5°C / min. From the obtained data, the storage modulus (G') of the pressure-sensitive adhesive sheet at temperatures of -20°C, 0°C, 25°C, 40°C, 60°C, and 80°C was determined. In addition, the temperature at which Tanδ was maximized, i.e., the peak temperature, was read to determine the measured Tg of the pressure-sensitive adhesive sheet.

[0105] [Gel Fraction] One release sheet was peeled off from each of the pressure-sensitive adhesive sheets 1 to 11 with release film, and the pressure-sensitive adhesive sheet side was attached to a 50 mm × 100 mm SUS mesh sheet (200 mesh). Then, the other release sheet was peeled off, and the SUS mesh sheet was folded back from the center in the longitudinal direction to encase the sample. The sample was then immersed in a sealed container containing 250 g of ethyl acetate at 23°C for 24 hours, and the gel fraction (% by mass) was measured from the change in mass.

[0106] [Peel Strength] For each of the pressure-sensitive adhesive sheets 1 to 11 with release film, one release film was peeled off and a 100 μm PET film (manufactured by Mitsubishi Chemical Corporation, "Diafoil T100") was attached as a backing film. This was then cut to a length of 150 mm and a width of 10 mm, and the remaining release film was peeled off, and the exposed adhesive surface was roll-pressed onto soda lime glass to form a bonded product. The bonded product was autoclaved (60 ° C, gauge pressure 0.2 MPa, 20 minutes) for finish bonding, and then aged at a temperature of 23 ° C and 50% RH for 12 hours to prepare a sample for adhesive strength measurement. The peel strength (N / cm) of the above sample was measured when peeled at a peel angle of 180 ° and a peel speed of 60 mm / min in an environment of 23 ° C and 50% RH.

[0107] [Optical properties] For each of the pressure-sensitive adhesive sheets 1 to 11 with release film, one release sheet was peeled off and the pressure-sensitive adhesive sheet side was attached to soda-lime glass (thickness 0.6 mm), and then the other release sheet was peeled off and attached to the soda-lime glass to prepare a test piece having a configuration of "soda-lime glass / pressure-sensitive adhesive layer / soda-lime glass". The total light transmittance and haze were measured using the obtained test pieces.

[0108] The total light transmittance was measured using a HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). This instrument conforms to JIS K7361-1. Haze was calculated by measuring the diffuse transmittance and total light transmittance using a HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) and substituting the obtained values ​​of diffuse transmittance and total light transmittance into the following formula 4. [Formula 4] Haze (%) = (Diffuse transmittance / Total light transmittance) × 100

[0109] The refractive index of each of the pressure-sensitive adhesive sheets 1 to 11, from which the release films had been peeled off from both sides, was measured in accordance with JIS K7124 using an Abbe refractometer manufactured by Atago and sodium D line (589 nm) as a light source.

[0110] [Measurement of Release Film Peel Force] Release film-attached PSA sheets 1 to 11 were cut to a length of 200 mm and a width of 50 mm, and then the heavy release film (heavy separator) side was roll-pressed to glass via double-sided tape. The light release film (light separator) was peeled at a peel angle of 180° and a peel speed of 300 mm / min in an environment of 23°C and 50% RH, and the peel force (N / cm) was recorded as the light separator peel force. Similarly, after cutting to a length of 200 mm and a width of 50 mm, the light separator was peeled, and the exposed adhesive surface was roll-pressed to glass. The heavy separator was peeled at a peel angle of 180° and a peel speed of 300 mm / min in an environment of 23°C and 50% RH, and the peel force (N / cm) was recorded as the heavy separator peel force. The heavy separator peel force / light separator peel force ratio was recorded.

[0111]

[0112] Examples 1 to 6 The release film (Y3), which is a light separator, was peeled off from the release film-attached pressure-sensitive adhesive sheet ((Y1) / (X1) / (Y3)) shown in Table 2 to give release film (Y1) / adhesive layer (X1), while the release film (Y4), which is a light separator, was peeled off from the release film-attached pressure-sensitive adhesive sheet ((Y2) / (X2) / (Y4)) to give release film (Y2) / adhesive layer (X2). The adhesive surface of the adhesive layer (X1) and the adhesive surface of the adhesive layer (X2) were bonded together to produce a pressure-sensitive adhesive sheet (sample) with a release film having a layer structure of release film (Y1) / adhesive layer (X1)+adhesive layer (X2) / release film (Y2).

[0113] Example 7 The release film (Y3), which is a light separator, was peeled off from the release film-attached pressure-sensitive adhesive sheet ((Y1) / (X1) / (Y3)) shown in Table 2 to obtain release film (Y1) / adhesive layer (X1), while the release film, which is a light separator, of the release film-attached pressure-sensitive adhesive sheet constituting the intermediate layer was peeled off to obtain release film / adhesive sheet, and the adhesive surface of the adhesive layer (X1) was bonded to the adhesive surface of this adhesive sheet to obtain a pressure-sensitive adhesive sheet with a release film having a layer structure of release film (Y1) / adhesive layer (X1) / adhesive layer of intermediate layer / release film of intermediate layer. Next, the release film (Y4), which is a light separator, was peeled off from the pressure-sensitive adhesive sheet with release film ((Y2) / (X2) / (Y4)) to leave release film (Y2) / adhesive layer (X2), and the release film, which is a heavy separator, of the pressure-sensitive adhesive sheet with release film that constitutes the intermediate layer was peeled off and the adhesive surface of the adhesive layer (X2) was bonded to the adhesive surface of that adhesive sheet, to produce a pressure-sensitive adhesive sheet (sample) with release film having a layer structure of release film (Y1) / adhesive layer (X1) + adhesive layer of intermediate layer + adhesive layer (X2) / release film (Y2).

[0114] Comparative Examples 1 to 4 Each of the pressure-sensitive adhesive sheets with release film shown in Table 2 was used as an evaluation sample.

[0115] <Evaluation> The release film-attached pressure-sensitive adhesive sheets (samples) produced or prepared in Examples 1 to 7 and Comparative Examples 1 to 4 were evaluated as follows.

[0116] [Lamination Interface] The pressure-sensitive adhesive sheets with release films produced or prepared in the Examples and Comparative Examples were cut with a feather blade that had been immersed in liquid nitrogen and cooled, and the cross sections were observed with an electron microscope (device: Nikon LV100ND, observed image: transmitted image, magnification: 20x). The number of observed lamination interfaces was recorded.

[0117] [Measurement of Release Film Peel Force] The pressure-sensitive adhesive sheets with release films produced or prepared in the Examples and Comparative Examples were cut to a length of 200 mm and a width of 50 mm, and the heavy separator side was roll-pressed to glass via double-sided tape. The light separator was peeled at a peel angle of 180° and a peel speed of 300 mm / min in an environment of 23°C and 50% RH, and the peel force (N / cm) was recorded as the light separator peel force. Similarly, after cutting to a length of 200 mm and a width of 50 mm, the light separator was peeled, and the exposed adhesive surface was roll-pressed to glass. The heavy separator was peeled at a peel angle of 180° and a peel speed of 300 mm / min in an environment of 23°C and 50% RH, and the peel force (N / cm) was recorded as the heavy separator peel force. The heavy separator peel force / light separator peel force was recorded as the peel force ratio.

[0118] [Evaluation of storage stability] A paper tube with an inner diameter of 10 inches (width 1250 mm) was prepared, and each of the pressure-sensitive adhesive sheets with release film produced or prepared in the Examples and Comparative Examples was wound around a width of 1000 mm for 200 m, with a light separator on the outside and a heavy separator on the inside, and then a 30-day storage test was carried out at 23°C and 50% RH. After the test, the roll sample was unwound and its appearance was checked. Samples that could not be wound around a roll and exhibited poor appearance such that the release film peeled off were rated "XX (bad)", samples that could be wound around a roll but exhibited poor appearance such that the separator peeled off when unwound after the 30-day storage test were rated "X (usual)", and samples that still had good appearance after the storage test were rated "○ (good)".

[0119] [Evaluation of Handling Efficiency] The pressure-sensitive adhesive sheets with release films produced or prepared in the Examples and Comparative Examples were cut to 210 x 300 mm using a Thomson punch to prepare 10 samples. The handleability was evaluated when these light separators were peeled off diagonally by hand. If the light separator could not be peeled off properly and the heavy separator side interface peeled off, or if one or more of the 10 sheets had defects, this was evaluated as "X", and if the light separator could be peeled off from all 10 sheets without any defects, this was evaluated as "O".

[0120] [Irregularity Conformability: Evaluation of Lamination Appearance] The pressure-sensitive adhesive sheets with release films prepared or prepared in the Examples and Comparative Examples were cut to 52 x 80 mm using a Thomson punch with the release film still laminated. One side of the release film was peeled off, and the exposed adhesive surface was pressed and bonded using a vacuum press to the printed surface of soda-lime glass (82 mm x 54 mm x 0.5 mm thick) with a 5 mm peripheral edge printed to a thickness of 50 μm, so that all four sides of the pressure-sensitive adhesive sheet overlapped the printed step (temperature 23 ° C, press pressure 0.3 MPa). Next, the remaining release film was peeled off, and a PET film (Diafoil T100-200, 82 mm x 54 mm x 0.2 mm thick) was laminated using a 2 kg hand roll, followed by autoclaving (60 ° C, gauge pressure 0.2 MPa, 20 minutes) for finish bonding, producing a stepped glass / double-sided pressure-sensitive adhesive sheet / PET film laminate.

[0121] The produced laminate was projected using a projector, and the unevenness of the PET film near the printing step was visually observed. The projector and screen were placed 2 m apart, and the laminate was placed parallel to the screen, 40 cm from the screen, between the projector and the screen, and the appearance projected on the screen was observed. A thick black shadow remained near the printing step, showing poor unevenness followability, was rated as "x (usual)." A good unevenness followability with only a slight faint shadow remaining on the printing step was rated as "○ (good)." A very good unevenness followability with no shadow visible near the printing step was rated as "◎ (very good)."

[0122]

[0123] (Discussion) From the above examples and comparative examples and the results of tests conducted by the inventors, it is believed that the pressure-sensitive adhesive sheet of the present invention can have good step-following properties for large steps if the thickness is 300 μm or more. It has been confirmed that if the thicknesses of the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) are both 100 μm or more and the ratio (x2 / x1) of the thickness (x2) of the pressure-sensitive adhesive layer (X2) to the thickness (x1) of the pressure-sensitive adhesive layer (X1) is 1 to 3, various performances can be improved in a bonding configuration with few lamination interfaces (few adhesive layers).

[0124]

[0043] Furthermore, it was confirmed that, as described above, if two or more pressure-sensitive adhesive sheets each having a thickness of 100 μm or more are separately prepared and then these pressure-sensitive adhesive sheets are bonded together to prepare a pressure-sensitive adhesive sheet of the present invention having an interface, it can be made into a roll suitable for storage and transportation, and therefore storage stability can be improved. Furthermore, it was also confirmed that the release films on both sides can be easily peeled off because the peel force (α1) between the release film (Y1) and the pressure-sensitive adhesive layer (X1) is greater than the peel force (α2) between the release film (Y2) and the pressure-sensitive adhesive layer (X2).

Claims

1. An adhesive sheet having an adhesive layer (X1) and an adhesive layer (X2), wherein both the adhesive layer (X1) and the adhesive layer (X2) contain an adhesive component derived from a (meth)acrylic polymer (A), the total thickness of the adhesive sheet is 300 μm or more, the thicknesses of both the adhesive layer (X1) and the adhesive layer (X2) are 100 μm or more, and the ratio (x2 / x1) of the thickness (x2) of the adhesive layer (X2) to the thickness (x1) of the adhesive layer (X1) is 1 to 3.

2. The adhesive sheet according to claim 1, wherein an interface between the adhesive layer (X1) and the adhesive layer (X2) is observed when the sheet cross-section of the adhesive sheet is observed with an electron microscope.

3. The adhesive sheet according to claim 1, wherein both the adhesive layer (X1) and the adhesive layer (X2) have a storage elastic modulus G' at 25°C of 1 kPa or more and 1000 kPa or less.

4. The adhesive sheet according to claim 1, wherein both the adhesive layer (X1) and the adhesive layer (X2) have a storage elastic modulus G' at 60°C of 0.1 kPa or more and 200 kPa or less.

5. The adhesive sheet according to claim 1, wherein both the adhesive layer (X1) and the adhesive layer (X2) have a glass transition temperature (Tg) of -50°C or more and 5°C or less.

6. A laminate for an image display device, comprising a configuration in which two optical members are laminated via the adhesive sheet according to any one of claims 1 to 5, wherein the size of the optical member is 10 inches or more and 100 inches or less.

7. An adhesive sheet roll body set having a release film-attached adhesive sheet roll body (Z1) having a layer configuration of release film (Y1) / adhesive layer (X1) / release film (Y3) and a release film-attached adhesive sheet roll body (Z2) having a layer configuration of release film (Y2) / adhesive layer (X2) / release film (Y4), wherein the peeling force (α1) between the release film (Y1) and the adhesive layer (X1) is greater than the peeling force (α3) between the release film (Y3) and the adhesive layer (X1), the peeling force (α2) between the release film (Y2) and the adhesive layer (X2) is greater than the peeling force (α4) between the release film (Y4) and the adhesive layer (X2), and the peeling force ratio (α1 / α2) between the peeling force (α1) of the release film (Y1) / adhesive layer (X1) and the peeling force (α2) of the release film (Y2) / adhesive layer (X2) is 1.1 or more.

8. The pressure-sensitive adhesive sheet roll body set according to claim 7, wherein both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) contain a pressure-sensitive adhesive component derived from a (meth)acrylic polymer (A).

9. The pressure-sensitive adhesive sheet roll body set according to claim 7, wherein the thicknesses of both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) are 100 μm or more.

10. The pressure-sensitive adhesive sheet roll body set according to claim 7, wherein both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) have a storage elastic modulus G' at a temperature of 25°C of 1 kPa or more and 1000 kPa or less.

11. The pressure-sensitive adhesive sheet roll body set according to claim 7, wherein both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) have a storage elastic modulus G' at a temperature of 60°C of 0.1 kPa or more and 200 kPa or less.

12. The pressure-sensitive adhesive sheet roll body set according to claim 7, wherein both the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) have a glass transition temperature (Tg) of -50°C or more and 5°C or less.

13. A method for manufacturing a pressure-sensitive adhesive sheet with a release film, comprising preparing a sheet roll body (Z1) composed of a pressure-sensitive adhesive sheet with a release film having a layer structure of release film (Y1) / pressure-sensitive adhesive layer (X1) / release film (Y3), wherein the peeling force (α1) between the release film (Y1) and the pressure-sensitive adhesive layer (X1) is greater than the peeling force (α3) between the release film (Y3) and the pressure-sensitive adhesive layer (X1), and a sheet roll body (Z2) composed of a pressure-sensitive adhesive sheet with a release film having a layer structure of release film (Y2) / pressure-sensitive adhesive layer (X2) / release film (Y4), wherein the peeling force (α2) between the release film (Y2) and the pressure-sensitive adhesive layer (X2) is greater than the peeling force (α4) between the release film (Y4) and the pressure-sensitive adhesive layer (X2). Then, unwind the sheet roll body (Z1), peel off the release film (Y3) to obtain the pressure-sensitive adhesive layer (X1) with the structure of release film (Y1) / pressure-sensitive adhesive layer (X1), unwind the sheet roll body (Z2), peel off the release film (Y4) to obtain the pressure-sensitive adhesive layer (X2) with the structure of release film (Y2) / pressure-sensitive adhesive layer (X2), and bond the adhesive surface of the pressure-sensitive adhesive layer (X1) and the adhesive surface of the pressure-sensitive adhesive layer (X2) to form a pressure-sensitive adhesive sheet with a release film having a layer structure of release film (Y1) / pressure-sensitive adhesive layer (X1) / pressure-sensitive adhesive layer (X2) / release film (Y2).

14. The method for manufacturing a pressure-sensitive adhesive sheet with a release film according to claim 13, wherein the peeling force ratio (α1 / α2) between the peeling force (α1) of the release film (Y1) / pressure-sensitive adhesive layer (X1) and the peeling force (α2) of the release film (Y2) / pressure-sensitive adhesive layer (X2) is 1.1 or more.

Images