Laminate film having adhesive layer

Abstract

To provide a laminate film having an adhesive layer suitable for inhibiting blocking at an end part as well as suitable for securing an easy removal of a one side film.SOLUTION: A laminate film X includes a film 10, an adhesive layer 20, and a film 30. The film 10 abuts on a first face 21 of the adhesive layer 20. The film 30 abuts on a second face 22 of the adhesive layer 20. The film 10 includes an extended end part 12. The extended end part 12 extends outward relative to an end face 23 of the adhesive layer 20 in a surface direction D orthogonal to a thickness direction H. The extended end part 12 includes a surface 12a flush with and connected to the end face 23, and is thinner than a main region part 11 abutting on the adhesive layer 20 at the film 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminated film having a pressure-sensitive adhesive layer. [Background technology]

[0002] A display panel has a laminated structure including elements such as a pixel panel, a polarizing film, a touch panel, and a cover film. In the manufacturing process of such a display panel, for example, an optically transparent adhesive sheet (optical adhesive sheet) is used to bond the elements included in the laminated structure. The optical adhesive sheet is manufactured, for example, in a form in which both sides of the sheet are covered with release liners (in the form of a laminated film having an adhesive layer).

[0003] Meanwhile, development of repeatedly foldable display panels for, for example, smartphones and tablet terminals is progressing. Specifically, a foldable display panel can be repeatedly deformed between a curved shape and a flat non-bent shape. In such a foldable display panel, each element in the laminated structure is made to be repeatedly foldable, and a thin optical adhesive sheet is used for bonding between such elements. An optical adhesive sheet for flexible devices such as a foldable display panel is described, for example, in Patent Document 1 below. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-111754 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, optical adhesive sheets for flexible devices are produced, for example, as follows.

[0006] First, a work film W' is prepared as shown in Fig. 12A. The work film W' is composed of a laminate film 90 as a long original sheet, and a long carrier film C' that supports the laminate film 90. The laminate film 90 has a release liner 91, an adhesive layer 92, and a release liner 93, in this order in the thickness direction H. The release liner 91 is in releasable contact with one side of the adhesive layer 92. The release liner 93 is in releasable contact with the other side of the adhesive layer 92. The carrier film C' supports the laminate film 90 from the release liner 91 side.

[0007] Next, as shown in FIG. 12B, the adhesive layer 92 of the laminated film 90 is pressed to form a plurality of sheet-like adhesive sheets 92A (pressing process). In the press process, as shown in FIG. 13, the blade 101 of the blade die 100 is pressed into the laminated film 90 from the release liner 93 side until it reaches the release liner 91. This forms an adhesive sheet 92A of a predetermined shape in plan view in the adhesive layer 92. In this process, a peripheral portion 92a is formed around the adhesive sheet 92A in the adhesive layer 92. The release liner 93 is also pressed to form a release liner 93A of the same shape in plan view as the adhesive layer 92, and a peripheral portion 93a is formed around the release liner 93A. Also, a cutting groove 95 is formed in the laminated film 90 from the release liner 93 side to the release liner 91.

[0008] After this pressing process, as shown in Figure 12C, peripheral portions 92a, 93a (Figure 12B) are removed from release liner 91 (removal process). Thereafter, as shown in Figure 12D, long release liner 91 is cut into sheet-like release liners 91A. This results in sheet-like laminated film 90A (release liner 91A / adhesive sheet 92A / release liner 93A) having an adhesive layer.

[0009] Adhesive sheets (adhesive layers) for flexible devices are required to be highly flexible so as to have sufficient conformability to an adherend when the device is bent and excellent stress relaxation. However, in the above-mentioned manufacturing method, the softer the adhesive layer 92 is, the easier it is for the adhesive layer 92 to adhere to the blade die 100 and to be pulled by the blade die 100 in the press processing step (FIG. 12B). Therefore, as shown in FIG. 14, a protruding portion 92E is easily formed in the adhesive sheet 92A after the press processing step. The protruding portion 92E is a portion of the end 92e of the adhesive sheet 92A that extends outward in the planar direction D beyond the end surface 93e of the release liner 92A.

[0010] When laminate films 90A are stacked, protruding portion 92E causes the ends of adjacent laminate films 90A to adhere to each other (end blocking). End blocking reduces the handleability of laminate film 90A. This type of defect also occurs when a surface protection film with an adhesive layer (with release liner 91A attached to the adhesive layer side) is formed on release liner 91A instead of adhesive sheet 92A and release liner 93A.

[0011] In the laminated film 90A, the release liner 91A has an extending end 91a. The extending end 91a extends outward from an end face 93e of the release liner 93A in the planar direction D. When the extending end 91a extends outward from the protruding end 92e in the planar direction D, such an extending end 91a suppresses the above-mentioned end blocking.

[0012] However, in conventional laminate film 90A, the force (peeling force) required to peel release liner 91A (having extended end portion 91a) from adhesive sheet 92A is relatively large, and therefore release liner 91A may not be properly peeled from adhesive sheet 92A.

[0013] The present invention provides a laminated film having a pressure-sensitive adhesive sheet that is suitable for suppressing edge blocking and for ensuring ease of peeling of one side of the film. [Means for solving the problem]

[0014] The present invention [1] includes a laminated film having an adhesive layer comprising a first surface and a second surface opposite to the first surface, a first film in contact with the first surface, and a second film in contact with the second surface, the first film having an extended end portion that extends outward beyond an end surface of the adhesive layer in a planar direction perpendicular to a thickness direction, the extended end portion having a surface that is flush with and connected to the end surface, and the extended end portion having an adhesive layer that is thinner than a main region of the first film that contacts the adhesive layer.

[0015] The present invention [2] includes a laminated film having the pressure-sensitive adhesive layer described in [1] above, in which the extension length of the extended end portion from the end face in the surface direction is 50 μm or more.

[0016] The present invention [3] includes a laminated film having the pressure-sensitive adhesive layer described in [1] or [2] above, in which the extension length of the extended end from the end face in the surface direction is 500 μm or less.

[0017] The present invention [4] includes a laminated film having a pressure-sensitive adhesive layer described in any one of [1] to [3] above, in which the ratio of the minimum thickness of the extended end portion to the thickness of the main region portion is 0.3 or more.

[0018] The present invention [5] includes a laminated film having a pressure-sensitive adhesive layer described in any one of [1] to [4] above, wherein the extended end portion has a thinnest portion and an outer portion that is outer than the thinnest portion in the planar direction, and the outer portion is thicker than the thinnest portion.

[0019] The present invention [6] includes a laminated film having the pressure-sensitive adhesive layer according to any one of the above [1] to [5], wherein the pressure-sensitive adhesive layer has a shear storage modulus of 100 kPa or less at 25°C.

[0020] The present invention [7] includes a laminate film having the pressure-sensitive adhesive layer according to any one of the above [1] to [6], wherein the pressure-sensitive adhesive layer has a gel fraction of 40% by mass or more and 80% by mass or less.

[0021] The present invention [8] includes a laminated film having the adhesive layer according to any one of the above [1] to [7], in a peel test in which the first film is peeled from the adhesive layer under conditions of 25°C, a peel angle of 180° and a tensile speed of 300 mm / min, the ratio of peel initiation force to peel force is 10 or less. Effect of the Invention

[0022] In the laminated film of the present invention, as described above, the first film has an extended end portion extending outward from the end face of the adhesive layer in the surface direction, the extended end portion has a surface that is flush with the end face of the adhesive layer, and is thinner than the main region of the first film that contacts the adhesive layer. The fact that the first film has an extended end portion and that the extended end portion has a surface that is flush with the end face of the adhesive layer is suitable for suppressing the above-mentioned end blocking. In addition, in the first film, the fact that the extended end portion is thinner than the main region portion (contacting the adhesive layer) is suitable for ensuring the ease of deformation (bending) of the extended end portion when the extended end portion of the first film is pulled to peel the first film from the adhesive layer. The fact that the extended end portion is easily deformed when the first film is peeled off reduces the peel initiation force for starting the peeling of the first film, and helps to ensure the ease of peeling of the first film. Therefore, the laminated film of the present invention is suitable for suppressing end blocking and for ensuring the ease of peeling of one side film. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic cross-sectional view of one embodiment of a laminated film (a laminated film having a pressure-sensitive adhesive layer) of the present invention. [Diagram 2] 2 is a partially enlarged cross-sectional view of the laminated film shown in FIG. [Diagram 3]3 shows an example of a method for producing the laminated film shown in Fig. 1. Fig. 3A shows a preparation step, Fig. 3B shows a half-cut step, and Fig. 3C shows a full-cut step. [Figure 4] FIG. 3C is a schematic plan view of an example of a region in the workpiece film after a half-cut process (FIG. 3B). [Diagram 5] 3D is a schematic plan view of an example of a region in the workpiece film after a full cutting process (FIG. 3C). FIG. [Figure 6] 1 shows a modified example of the half-cut process, in which the second film layer and the adhesive layer are melted by irradiation and scanning with a first laser light, and the melting points are shifted in a direction intersecting the scanning direction and repeated multiple times to form half-cut grooves. [Figure 7] 7 is a schematic plan view of an example of a region of the workpiece film after the half-cut process shown in FIG. 6. FIG. [Figure 8] This shows the full-cut process after the half-cut process shown in FIG. [Figure 9] 9 is a schematic plan view of an example of a region of the workpiece film after the full cutting process shown in FIG. 8. [Figure 10] 10A and 10B show a part of another example of the method for producing the laminated film shown in Fig. 1. Fig. 10A shows a full-cut process, and Fig. 10B shows a half-cut process. [Figure 11] 1 shows an example of a graph obtained by a peel test in which a release liner on a pressure-sensitive adhesive layer is peeled from the pressure-sensitive adhesive layer. [Figure 12] 12A shows an example of a method for producing a conventional laminated film having a pressure-sensitive adhesive layer, in which Fig. 12A shows a preparation step, Fig. 12B shows a pressing step, Fig. 12C shows a removal step, and Fig. 12D shows a cutting step. [Figure 13] This shows the press processing process using a blade die. [Figure 14] FIG. 2 is a partially enlarged cross-sectional view of an end portion of a conventional laminated film having a pressure-sensitive adhesive layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] 1, a laminated film X according to one embodiment of the present invention includes a film 10 (first film), an adhesive layer 20, and a film 30 (second film) in this order in a thickness direction H. The adhesive layer 20 has a first surface 21 and a second surface 22 opposite to the first surface 21. The film 10 is in contact with the first surface 21. The film 30 is in contact with the second surface 22. The laminated film X extends in a planar direction D perpendicular to the thickness direction H.

[0025] The film 10 is a release liner that can be peeled off from the adhesive layer 20. The film 10 has a main region 11 and an extended end 12. The main region 11 is a region of the film 10 that contacts the adhesive layer 20. As shown in FIG. 2, the extended end 12 extends outward from the end face 23 of the adhesive layer 20 in the planar direction D. The extended end 12 has a surface 12a that is flush with the end face 23 and a surface 12b that is outward from the surface 12a in the planar direction D. The surface 12a has, for example, an arc shape in the cross section shown in FIG. 2. The surface 12b has, for example, a straight shape or a slightly curved shape in the cross section shown in FIG. 2. In this embodiment, a top 12c is formed between the surface 12a and the surface 12b. The top 12c is, for example, pointed with an acute angle in the cross section shown in FIG. 2. The extended end 12 is thinner than the main region 11. That is, the extending end portion 12 is a thin-walled extending end portion.

[0026] The film 30 is, for example, a release liner, a functional optical film, or a base film (support film). The film 30 has a first surface 31 on the pressure-sensitive adhesive layer 20 side, a second surface 32 on the opposite side, and an end surface 33. The end surface 33 is connected to the end surface 23 of the pressure-sensitive adhesive layer 20 so as to be flush with each other.

[0027] At the end of the laminated film X, the end face 33 of the film 30, the end face 23 of the adhesive layer 20, and a portion of the surface 12a of the film 10 adjacent to the end face 23 form a curved shape (R shape) that widens outward and has a smaller radius of curvature as it moves away from the second surface 32 of the film 30 in the thickness direction H. In addition, the surface 12b of the extended end 12 is inclined or curved so as to widen outward as it moves away from the second surface 32 in the thickness direction H.

[0028] In the laminated film X, as described above, the film 10 has the extending end 12 that extends outward beyond the end face 23 of the pressure-sensitive adhesive layer 20 in the planar direction D, the extending end 12 has a surface 12a that is flush with the end face 23, and is thinner than the main region 11 of the film 10 that contacts the pressure-sensitive adhesive layer 20. The fact that the film 10 has the extending end 12 and that the extending end 12 has a surface 12a that is flush with the end face 23 of the pressure-sensitive adhesive layer 20 is suitable for suppressing the above-mentioned end blocking.

[0029] Furthermore, in the film 10, the extending end 12 being thinner than the main region 11 (contacting the adhesive layer 20) is suitable for ensuring the ease of deformation (bending) of the extending end 12 when the extending end 12 of the film 10 is pulled to peel the film 10 from the adhesive layer 20. The ease of deformation of the extending end 12 when the film 10 is peeled reduces the peel initiation force for starting the peeling of the film 10, and helps to ensure the ease of peeling of the film 10.

[0030] As described above, the laminated film X is suitable for suppressing edge blocking and for ensuring that the film 10 can be easily peeled off.

[0031] From the viewpoint of suppressing the above-mentioned blocking in the laminated film X, the extension length d1 (FIG. 2) of the extending end 12 from the end face 23 in the plane direction D (direction perpendicular to the end face 23 in a plan view) is preferably 50 μm or more, more preferably 70 μm or more, and even more preferably 100 μm or more. From the viewpoint of efficient production of the laminated film X, the extension length d1 is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less.

[0032] The ratio (h2 / h1) of the minimum thickness h2 of the extended end portion 12 to the thickness h1 of the main region portion 11 of the film 10 is preferably 0.3 or more, more preferably 0.4 or more, and even more preferably 0.43 or more, from the viewpoint of ensuring the strength of the extended end portion 12. The ratio (h2 / h1) is, for example, 0.7 or less, 0.8 or less, or 0.9 or less.

[0033] The thickness h1 of the main region 11 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, from the viewpoint of ensuring the protective function of the pressure-sensitive adhesive layer 20 by the film 10. The thickness h1 of the main region 11 is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less, from the viewpoint of making the laminated film X thinner.

[0034] In this embodiment, the extending end 12 has the thinnest part 12p having the above-mentioned minimum thickness h2 and an outer part 12q that is located outside the thinnest part 12p in the surface direction D. The outer part 12q is thicker than the thinnest part 12p. The extending end 12 of the film 10 having such a thinnest part 12p and an outer part 12q is suitable for achieving both the ease of deformation (bending) of the extending end 12 when the film 10 is peeled off from the adhesive layer 20 and the ease of catching an abutting element (such as a finger of a peeling operator) on the extending end 12. In addition, in the extending end 12, the thinnest part 12p is located midway from the end face 23 side of the adhesive layer 20 to the apex 12c (in this embodiment, from the center to the apex 12c side).

[0035] The ratio (h3 / h2) of the thickness h3 of the outer portion 12q to the minimum thickness h2 at the extended end 12 is preferably 1.2 or more, more preferably 1.5 or more, even more preferably 1.8 or more, from the viewpoint of ensuring the ease with which the abutting element catches on the extended end 12 when peeled off, and is preferably 3.0 or less, more preferably 2.5 or less, even more preferably 2.2 or less.

[0036] The distance d2 (FIG. 2) between the outer end of the film 10 and the inner end of the adhesive layer 20 in the surface direction D (the direction perpendicular to the end face 23 in a plan view) is preferably 1000 μm or less, more preferably 700 μm or less, and even more preferably 500 μm or less. The distance d2 is, for example, 50 μm or more or 70 μm or more. The region between the outer end of the film 10 and the inner end of the adhesive layer 20 in the surface direction D is a part of the edge region that can be used as an alignment mark (edge ​​alignment mark) for detecting the end of the laminated film X. When the distance d2 is 1000 μm or less (preferably 700 μm or less, more preferably 500 μm or less), erroneous detection of the edge alignment mark by the detection camera can be suppressed (if the edge alignment mark is too large, erroneous detection occurs).

[0037] The thickness of the pressure-sensitive adhesive layer 20 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more, from the viewpoint of ensuring the adhesive strength of the pressure-sensitive adhesive layer 20. The thickness of the pressure-sensitive adhesive layer 20 is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less, from the viewpoint of making the pressure-sensitive adhesive layer 20 thinner.

[0038] The gel fraction of the pressure-sensitive adhesive layer 20 is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less, from the viewpoint of ensuring the softness of the pressure-sensitive adhesive layer 20. The gel fraction of the pressure-sensitive adhesive layer 20 is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more, from the viewpoint of ensuring the cohesive force of the pressure-sensitive adhesive layer 20. Methods for adjusting the gel fraction include, for example, selecting the type of base polymer in the pressure-sensitive adhesive layer 20, adjusting the molecular weight, and adjusting the blending amount. The method for measuring the gel fraction is as described below in the examples.

[0039] The shear storage modulus of the adhesive layer 20 at 25°C is preferably 100 kPa or less, more preferably 90 kPa or less, and even more preferably 80 kPa or less, from the viewpoint of ensuring the softness required for the adhesive layer for flexible device applications in the adhesive layer 20. The shear storage modulus of the adhesive layer 20 at 25°C is preferably 10 kPa or more, more preferably 15 kPa or more, even more preferably 20 kPa or more, and particularly preferably 25 kPa or more, from the viewpoint of ensuring the adhesive strength of the adhesive layer 20. Examples of the method for adjusting the shear storage modulus of the adhesive layer 20 include selecting the type of base polymer in the adhesive layer 20, adjusting the molecular weight, adjusting the blending amount, adjusting the glass transition temperature, and adjusting the degree of crosslinking. Examples of the method for adjusting the shear storage modulus of the adhesive layer 20 include selecting the component other than the base polymer in the adhesive layer 20 and adjusting the blending amount. The shear storage modulus of the adhesive layer is determined by dynamic viscoelasticity measurement. The method for measuring the shear storage modulus is specifically as described below in the examples.

[0040] The peel initiation force F1 for initiating peeling of the film 10 from the pressure-sensitive adhesive layer 20 is preferably 1.5 N / 50 mm or less, more preferably 1.3 N / 50 mm or less, and even more preferably 1.2 N / 50 mm or less, from the viewpoint of ensuring easy peeling of the film 10. The peel initiation force F1 is preferably 0.5 N / 50 mm or more, more preferably 0.65 N / 50 mm or more, and even more preferably 0.75 N / 50 mm or more, from the viewpoint of suppressing unintended peeling of the film 10.

[0041] In this embodiment, the peeling initiation force is the force required in the peeling initiation process when peeling off the film peelably attached to the adhesive layer from the adhesive layer. In the peeling initiation process, a force is applied to the film so that the film deforms in a direction away from the adhesive layer. As a result, the edge of the adhesive layer attached to the film and its vicinity are elastically deformed once so as to follow the deformation of the film. Then, when the film is pulled with a force large enough to pull the film away from the elastically deformed end of the adhesive layer, a cleavage occurs between the edge of the adhesive layer and its vicinity and the film, and peeling starts. That is, the peeling initiation force is the force required in the peeling initiation process to pull the film away from the elastically deformed end of the adhesive layer to start peeling the film from the adhesive layer. Such a peeling initiation force can be measured by the method described later in the Examples below. Examples of the method for adjusting such a peeling initiation force include, for example, adjusting the thickness of the film and selecting the type of release treatment agent on the adhesive layer side surface of the film.

[0042] The peeling force F2 for peeling the film 10 from the pressure-sensitive adhesive layer 20 after the start of peeling of the film 10 from the pressure-sensitive adhesive layer 20 is preferably 0.2 N / 50 mm or less, more preferably 0.17 N / 50 mm or less, and even more preferably 0.16 N / 50 mm or less, from the viewpoint of ensuring easy peeling of the film 10. The peeling force F2 is preferably 0.10 N / 50 mm or more, more preferably 0.12 N / 50 mm or more, and even more preferably 0.14 N / 50 mm or more, from the viewpoint of suppressing unintended peeling of the film 10.

[0043] The ratio (F1 / F2) of the peel initiation force F1 to the peel force F2 is preferably 10 or less, more preferably 9 or less, even more preferably 8 or less, and even more preferably 7.5 or less, from the viewpoint of ensuring ease of peeling of the film 10. The ratio (F1 / F2) is, for example, 1 or more, 3 or more, or 5 or more.

[0044] Figures 3A to 3C show an example of a method for producing the laminated film X. Figure 3A shows a preparation step, Figure 3B shows a half-cutting step, and Figure 3C shows a full-cutting step.

[0045] In the preparation step, a long work film W is prepared as shown in Fig. 3A. The work film W includes a laminate film X' and a carrier film C. The laminate film X' is a long original film. The carrier film C supports the laminate film X'.

[0046] The laminated film X' includes a film layer 10A (first film layer), an adhesive layer 20A, and a film layer 30A (second film layer) in this order in the thickness direction H. The adhesive layer 20A has a first surface 20a and a second surface 20b opposite the first surface 20a. The film layer 10A is in contact with the first surface 20a. The film layer 30A is in contact with the second surface 20b. The laminated film X' extends in a planar direction perpendicular to the thickness direction H.

[0047] The carrier film C is a single-sided adhesive film having an adhesive surface on one side in the thickness direction H. In the workpiece film W, the adhesive surface of the carrier film C is bonded to the film layer 10A side of the laminated film X'. That is, the workpiece film W specifically includes the carrier film C, the film layer 10A, the adhesive layer 20A, and the film layer 30A in this order in the thickness direction H.

[0048] Additionally, the carrier film C is wider than the laminated film X' in the width direction D2 (FIGS. 4 and 5) perpendicular to the flow direction D1 of the workpiece film W. The laminated film X' is disposed at the center position in the width direction D2 on the carrier film C. The width (length in the width direction D2) of the laminated film X' is, for example, 200 mm or more, preferably 280 mm or more, more preferably 400 mm or more, and is, for example, 2000 mm or less, preferably 1800 mm or less, more preferably 1600 mm or less. Such a workpiece film W is run through the production line.

[0049] The film layer 10A is a release liner. Examples of the material of the release liner include polyester, polyolefin, and polycarbonate. Examples of polyester include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Examples of polyolefin include polyethylene, polypropylene, and cycloolefin polymer (COP). The film layer 10A as a release liner is releasably in contact with the first surface 21 of the adhesive layer 20A. The surface of such a film layer 10A (the surface on the adhesive layer 20A side) is preferably subjected to a release treatment. Examples of the release treatment include a silicone release treatment and a fluorine release treatment.

[0050] The adhesive layer 20A is formed from an adhesive composition. The adhesive composition includes a base polymer. The base polymer is an adhesive component that exhibits adhesiveness. Examples of the base polymer include an acrylic polymer, a polyurethane polymer, a polyamide polymer, and a polyvinyl ether polymer. The base polymer may be used alone or in combination of two or more kinds. From the viewpoint of ensuring good transparency and adhesiveness in the adhesive layer 20A, an acrylic polymer is preferably used as the base polymer.

[0051] An acrylic polymer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid ester. "(Meth)acrylic" means acrylic and / or methacrylic. As the (meth)acrylic acid ester, preferably, a (meth)acrylic acid alkyl ester is used, and more preferably, a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 20 carbon atoms is used.

[0052] Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, pentyl (meth)acrylate, n-hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (i.e., lauryl (meth)acrylate), isotridecyl (meth)acrylate, and tetradecyl (meth)acrylate. The (meth)acrylic acid alkyl ester is preferably at least one selected from the group consisting of 2-ethylhexyl acrylate (2EHA), lauryl acrylate (LA), and n-butyl acrylate (BA). The proportion of (meth)acrylic acid alkyl ester in the monomer components is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, from the viewpoint of properly expressing basic properties such as adhesiveness in the adhesive layer 20A, and is, for example, 99% by mass or less.

[0053] The monomer component may include a copolymerizable monomer that is copolymerizable with the (meth)acrylic acid alkyl ester. The copolymerizable monomer may include, for example, a monomer having a polar group. The polar group-containing monomer may include, for example, a hydroxy group-containing monomer, a carboxy group-containing monomer, and a monomer having a nitrogen atom-containing ring. The polar group-containing monomer is useful for modifying the acrylic polymer, such as introducing a crosslinking point into the acrylic polymer and ensuring the cohesive force of the acrylic polymer.

[0054] Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. As the hydroxyl group-containing monomer, at least one selected from the group consisting of 2-hydroxyethyl acrylate (2HEA) and 4-hydroxybutyl acrylate (4HBA) is preferably used. The ratio of the hydroxyl group-containing monomer in the monomer component is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring the cohesive force in the adhesive layer 20A. The ratio is preferably 20% by mass or less, more preferably 10% by mass or less, from the viewpoint of adjusting the polarity of the acrylic polymer. The polarity of the acrylic polymer is related to the compatibility of the acrylic polymer with various additive components in the adhesive layer 20A.

[0055] Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-(meth)acryloyl-2-pyrrolidone, and acryloylmorpholine. As a monomer having a nitrogen atom-containing ring, N-vinyl-2-pyrrolidone (NVP) is preferably used. The ratio of the monomer having a nitrogen atom-containing ring in the monomer component is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, from the viewpoints of ensuring the cohesive force in the pressure-sensitive adhesive layer 20A and ensuring the adhesive force to the adherend in the pressure-sensitive adhesive layer 20A. The ratio is preferably 30% by mass or less, more preferably 20% by mass or less, from the viewpoints of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer.

[0056] The base polymer preferably has a crosslinked structure. Examples of methods for introducing a crosslinked structure into the base polymer include the following first and second methods. In the first method, a base polymer having a functional group capable of reacting with a crosslinking agent and a crosslinking agent are blended into an adhesive composition, and the base polymer and the crosslinking agent are reacted in an adhesive sheet. In the second method, a polyfunctional compound is included as a crosslinking agent in the monomer components forming the base polymer, and a base polymer having a branched structure (crosslinked structure) introduced into the polymer chain is formed by polymerization of the monomer components. These methods may be used in combination.

[0057] The crosslinking agent used in the first method includes, for example, a compound that reacts with the functional group (such as a hydroxyl group and a carboxyl group) contained in the base polymer. Such crosslinking agents include, for example, an isocyanate crosslinking agent, a peroxide crosslinking agent, and an epoxy crosslinking agent. The crosslinking agent may be used alone or in combination of two or more kinds.

[0058] In the second method, the monomer components (including the multifunctional monomer for introducing a crosslinked structure and other monomers) may be polymerized at once or in multiple stages. In the multistage polymerization method, first, a monofunctional monomer for forming a base polymer is polymerized (preliminary polymerization), thereby preparing a prepolymer composition containing a partial polymer (a mixture of a polymer with a low degree of polymerization and an unreacted monomer). Next, a multifunctional monomer is added as a crosslinking agent to the prepolymer composition, and then the partial polymer and the multifunctional monomer are polymerized (main polymerization). As the multifunctional monomer, for example, a multifunctional (meth)acrylate containing two or more ethylenically unsaturated double bonds in one molecule can be mentioned. As the multifunctional monomer, a multifunctional acrylate is preferable from the viewpoint of being able to introduce a crosslinked structure by active energy ray polymerization (photopolymerization). Examples of polyfunctional (meth)acrylates include dipentaerythritol hexaacrylate (DPHA), ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate.

[0059] The acrylic polymer can be formed by polymerizing the above-mentioned monomer components. Examples of the polymerization method include solution polymerization, solvent-free photopolymerization (e.g., UV polymerization), bulk polymerization, and emulsion polymerization. Examples of the solvent used in solution polymerization include ethyl acetate and toluene. Examples of the polymerization initiator used include a thermal polymerization initiator and a photopolymerization initiator.

[0060] From the viewpoint of ensuring the cohesive strength in the pressure-sensitive adhesive layer 20A, the weight average molecular weight of the base polymer is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 500,000 or more. The weight average molecular weight is preferably 5 million or less, more preferably 3 million or less, and even more preferably 2 million or less. The weight average molecular weight of the base polymer is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0061] From the viewpoint of ensuring the softness of the pressure-sensitive adhesive layer 20A, the glass transition temperature (Tg) of the base polymer is preferably 0° C. or lower, more preferably −10° C. or lower, and even more preferably −20° C. or lower. The glass transition temperature is, for example, −80° C. or higher.

[0062] The glass transition temperature (Tg) of the base polymer can be calculated based on the following Fox formula (theoretical value). The Fox formula is expressed as the glass transition temperature (Tg) of a polymer and the glass transition temperature (Tg) of a homopolymer of the monomer that constitutes the polymer. iIn the Fox formula below, Tg represents the glass transition temperature (°C) of a polymer, Wi represents the weight fraction of monomer i constituting the polymer, and Tgi represents the glass transition temperature (°C) of a homopolymer formed from monomer i. For the glass transition temperature of a homopolymer, a literature value can be used. For example, the glass transition temperatures of various homopolymers are listed in "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999). On the other hand, the glass transition temperature of a homopolymer of a monomer can also be determined by the method specifically described in JP-A-2007-51271.

[0063] Fox formula 1 / (273+Tg)=Σ[Wi / (273+Tgi)]

[0064] The adhesive composition may contain other components as necessary. Examples of the other components include a solvent, a silane coupling agent, an ultraviolet absorber, a tackifier, a softener, and an antioxidant. Examples of the solvent include a polymerization solvent that is used as necessary during polymerization of the acrylic polymer, and a solvent that is added to the polymerization reaction solution after polymerization. Examples of the solvent include ethyl acetate and toluene.

[0065] The haze of the adhesive layer 20A is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. The haze of the adhesive layer 20A can be measured using a haze meter in accordance with JIS K7136 (2000). Examples of haze meters include "NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd. and "HM-150 type" manufactured by Murakami Color Research Laboratory Co., Ltd.

[0066] The film layer 30A is, for example, a release liner, a functional optical film, or a substrate film (support film).

[0067] Examples of the material of the release liner include polyester, polyolefin, and polycarbonate. Specifically, the materials of the release liner described above for the film layer 10A are included. The film layer 30A as the release liner is in peelable contact with the second surface 20b of the adhesive layer 20A. The surface of such a film layer 30A (the surface on the adhesive layer 20A side) is preferably subjected to a release treatment. Examples of the release treatment include a silicone release treatment and a fluorine release treatment. From the viewpoint of ensuring the protective function for the adhesive layer 20A, the thickness of the film layer 30A as the release liner is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. From the viewpoint of making the laminated film X to be manufactured thinner, the thickness of the film layer 30A as the release liner is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less.

[0068] Examples of the functional optical film include a polarizing film and a retardation film. The functional optical film may be other optical films such as a panel reinforcement material. When the film layer 30A is a functional optical film, the second surface 20b of the adhesive layer 20A is bonded to the film layer 30A. The film layer 30A as a functional optical film and the adhesive layer 20A form a functional optical film with an adhesive layer.

[0069] The polarizing film may be, for example, a hydrophilic polymer film that has been dyed with a dichroic substance and then stretched. The dichroic substance may be, for example, iodine and a dichroic dye. The hydrophilic polymer film may be, for example, a polyvinyl alcohol (PVA) film, a partially formalized PVA film, and a partially saponified film of an ethylene-vinyl acetate copolymer. The polarizing film may also be a polyene-oriented film. The material of the polyene-oriented film may be, for example, a dehydrated product of PVA and a dehydrochlorinated product of polyvinyl chloride. The polarizing film may have a protective film bonded to one surface and / or the other surface in the thickness direction via an adhesive. The thickness of the polarizing film is preferably 10 μm or more, more preferably 20 μm or more, from the viewpoint of ensuring the function, strength, and durability of the polarizing film. The thickness of the polarizing film is preferably 500 μm or less, more preferably 300 μm or less, from the viewpoint of making the laminated film X thinner.

[0070] Examples of the retardation film include λ / 2 wavelength film, λ / 4 wavelength film, and viewing angle compensation film. Examples of the material of the retardation film include polymer films that are birefringent by stretching. Examples of the polymer films include cellulose films and polyester films. Examples of the cellulose films include triacetyl cellulose films. Examples of the polyester films include polyethylene terephthalate films, polyethylene naphthalate films, and polybutylene terephthalate films. Examples of the retardation film include films that include a substrate such as a cellulose film and an orientation layer on the substrate. The orientation layer is formed from a liquid crystal compound such as a liquid crystal polymer. The thickness of the retardation film is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of ensuring the function and strength of the retardation film. The thickness of the retardation film is preferably 100 μm or less, more preferably 80 μm or less, from the viewpoint of making the laminated film X thinner.

[0071] Examples of materials for the base film include the materials mentioned above as the materials for the release liner. When the film layer 30A is a base film, the second surface 20b of the adhesive layer 20A is bonded to the film layer 30A. The film layer 30A as a base film and the adhesive layer 20A form a single-sided adhesive sheet. From the viewpoint of ensuring the strength of the base film, the thickness of the base film is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. From the viewpoint of making the laminated film X thinner, the thickness of the base film is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less.

[0072] The laminated film X' can be produced, for example, as follows. First, the above-mentioned adhesive composition is applied onto the film layer 30A to form a coating film. Next, the film layer 10A is laminated onto the coating film on the film layer 30A. Next, the coating film between the film layers 10A and 30 is dried, and the coating film is irradiated with light as necessary. In this way, the adhesive layer 20A is formed between the film layers 10A and 30. Examples of the application method of the adhesive composition include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating. The drying temperature of the coating film is, for example, 50°C to 200°C. The drying time is, for example, 5 seconds to 20 minutes.

[0073] In the half-cut process, as shown in FIG. 3B, the half-cut groove G1 is formed by laser processing the work film W. Specifically, the laser processing device irradiates and scans the work film W with laser light L1 (first laser light) from the film layer 30A side, thereby melting the film layer 30A and the adhesive layer 20A in the laminated film X' to form the half-cut groove G1. The half-cut groove G1 is formed so as to follow a predetermined cutting line (design cutting line) in the work film W. As a result, in the adhesive layer 20A, the individualized adhesive layer 20 and the peripheral portion 25 around the adhesive layer 20 are formed. In addition, in the film layer 30A, the film 30 on the adhesive layer 20 and the peripheral portion 35 around the film 30 are formed. In the film layer 10A, a groove G1a (a part of the half-cut groove G1) is formed. The groove G1a is formed along the end surface 23 of the adhesive layer 20. FIG. 4 is a plan view that shows a schematic example of an area in the work film W after the half-cut process. In Fig. 4, the half-cut groove G1 is shown with hatching. The partial cross-sectional view shown in Fig. 3B corresponds to a partial cross-sectional view taken along line II in the workpiece film W shown in Fig. 4.

[0074] Examples of lasers for laser processing include gas lasers, solid-state lasers, and semiconductor lasers. Examples of gas lasers include excimer lasers and CO2 lasers (10.6 μm) (numbers in parentheses indicate the laser wavelengths. The same applies below for lasers). Examples of excimer lasers include F2 excimer lasers (157 nm), ArF excimer lasers (193 nm), KrF excimer lasers (248 nm), and XeCl excimer lasers (308 nm). Examples of solid-state lasers include Nd:YAG lasers (1064 nm), the second harmonic of Nd:YAG lasers (532 nm), the third harmonic of Nd:YAG lasers (355 nm), and the fourth harmonic of Nd:YAG lasers (266 nm). Examples of semiconductor lasers include semiconductor lasers with a wavelength of 405 nm. As the laser light L1 in the half-cutting step (FIG. 3B), a CO2 laser is preferable from the viewpoint of appropriately cutting both the pressure-sensitive adhesive layer 20A and the film layer 30A, which are different in material and optical properties (such as absorbance).

[0075] The laser light L1 is preferably a Gaussian type laser light or a top hat type laser light. Such a configuration is preferable for appropriately forming the half-cut groove G1 in the half-cut process. The Gaussian type laser light is a laser light whose energy intensity distribution has a Gaussian distribution. The top hat type laser light is a laser light whose energy intensity distribution has a top hat shape.

[0076] The output of the laser light L1 is, for example, 2 to 500 W. The pulse frequency of the laser light L1 is, for example, 10 to 100 kHz. The spot diameter of the laser light L1 on the work film W is, for example, 50 to 500 μm.

[0077] In the full-cut process, as shown in FIG. 3C, a full-cut groove G2 is formed by laser processing the workpiece film W. Specifically, a laser processing device irradiates and scans the workpiece film W with laser light L2 (second laser light) from the film layer 30A side, thereby melting the film layer 30A, the adhesive layer 20A, and the film layer 10A in the laminated film X' to form the full-cut groove G2. The full-cut groove G2 is formed along the half-cut groove G1 as shown in FIG. 5 (in FIG. 5, the full-cut groove G2 is shown with finer hatching than the half-cut groove G1). The partial cross-sectional view shown in FIG. 3C corresponds to a partial cross-sectional view taken along the line II-II in the workpiece film W shown in FIG. The half-cut groove G1 and the full-cut groove G2 extend parallel to each other adjacent to each other, and are continuously connected in the extension direction in the adjacent direction.

[0078] The laser light L2 in the full cutting process (FIG. 3C) is preferably a CO2 laser from the viewpoint of appropriately cutting the adhesive layer 20A and the film layers 10A and 30A, which are different in material and optical properties (such as absorbance). The laser light L2 may be a Gaussian type laser light or a top hat type laser light. The output of the laser light L2 is, for example, 2 to 500 W. The pulse frequency of the laser light L2 is, for example, 10 to 100 kHz. The spot diameter of the laser light L2 on the workpiece film W is, for example, 50 to 500 μm.

[0079] In this step, the peripheral portions 25, 35 between the adjacent half-cut grooves G1 are evaporated and removed, and the film layer 10A forms individual films 10. Then, a laminated film X (a laminated film having a pressure-sensitive adhesive layer) is formed on the carrier film C.

[0080] In this manufacturing method, after the half-cutting step (FIG. 3B) and the full-cutting step (FIG. 3C), the laminated film X is removed from the carrier film C. In this manner, the laminated film X can be manufactured.

[0081] The laminated film X is used, for example, as a supply material for an adhesive layer to be incorporated into the laminated structure of a flexible device during the manufacturing process of the device. An example of a flexible device is a flexible display panel. The flexible display panel has a laminated structure including elements such as a pixel panel, a polarizing film, a touch panel, and a cover film (surface protection film).

[0082] In this manufacturing method, the laminated film X is contoured by laser processing as described above. Laser processing is suitable for continuously contouring the work film while it is being continuously moved (it is not necessary to feed the work film intermittently for contour processing). Therefore, this manufacturing method is suitable for efficiently manufacturing the laminated film X.

[0083] In the half-cut process (FIG. 3B), the material of the workpiece film W is evaporated and removed in the portion where the workpiece film W is irradiated with the laser light L1. This forms the half-cut groove G1. In the full-cut process, the material of the workpiece film W is evaporated and removed in the portion where the workpiece film W is irradiated with the laser light. This forms the full-cut groove G2. As described above, the half-cut groove G1 and the full-cut groove G2 extend adjacent to each other in parallel, and are continuously connected in the extension direction in the adjacent direction. The half-cut groove G1 and the full-cut groove G2 connected in this way define the outer shape of the laminated film X (film 10 / adhesive layer 20 / film 30) on the carrier film C. Therefore, in the manufacturing method of the laminated film X (including the film 10 having the extended end portion 12), the removal process described above in relation to the conventional manufacturing method is not necessary. Therefore, the manufacturing method of the present invention is suitable for efficiently manufacturing the laminated film X.

[0084] In the half-cut process of the present manufacturing method, as shown in FIG. 6, the half-cut groove G1 may be formed by repeatedly fusion-cutting the film layer 30A and the adhesive layer 20A by irradiation and scanning with the laser light L1 multiple times while shifting the fusion points in a direction intersecting the scanning direction. The half-cut groove G1 separates the adhesive layer 20 in the adhesive layer 20A. FIG. 7 is a plan view that shows a schematic example of an area in the work film W after such a half-cut process (the half-cut groove G1 is shown hatched in FIG. 7). The partial cross-sectional view shown in FIG. 6 corresponds to the partial cross-sectional view of the work film W taken along line III-III shown in FIG. 7. Such a half-cut process is preferable for forming a wide half-cut groove G1. In addition, in this process (half-cut process), the half-cut groove G1 may be formed so as not to leave the peripheral parts 25, 35.

[0085] In the subsequent full-cut process, as shown in FIG. 8, the workpiece film W is irradiated with and scanned with a laser beam L2 from the film layer 30A side to melt and cut the film layer 30, the adhesive layer 20, and the film layer 10 in the laminated film X' to form a full-cut groove G2. The full-cut groove G2 is formed along the half-cut groove G1 as shown in FIG. 9 (in FIG. 9, the full-cut groove G2 is shown with finer hatching than the half-cut groove G1). The partial cross-sectional view shown in FIG. 8 corresponds to a partial cross-sectional view taken along the line IV-IV of the workpiece film W shown in FIG. 9. Specifically, the full-cut groove G2 is formed along the half-cut groove G1 on the outer side of the half-cut groove G1 with respect to the adhesive layer 20 that has been singulated by the half-cut groove G1. The half-cut groove G1 and the full-cut groove G2 extend parallel to each other adjacent to each other, and are continuously connected in the extension direction to each other adjacently. In the half-cut process shown in FIG. 6, when the half-cut groove G1 is formed so as not to leave the peripheral portions 25, 35, in the subsequent full-cut process, the laser light L2 is irradiated and scanned so as to follow, for example, the center in the width direction of the half-cut groove G1 to melt the film layer 10A.

[0086] Even after the half-cutting step (FIG. 6) and full-cutting step (FIG. 8) as described above, a laminated film X (film 10 / adhesive layer 20 / film 30) including a film 10 having an extended end portion 12 is formed on the carrier film C. Including the half-cutting step (FIG. 6), which is preferable for forming a wide half-cut groove G1, is preferable for producing a laminated film X including a film 10 having a longer extended end portion 12. The longer the extended end portion 12, the more the above-mentioned blocking can be suppressed.

[0087] The full-cutting step and the half-cutting step may be performed in this order in the manufacturing method of the laminated film X. Figures 10A and 10B show process diagrams in which the full-cutting step and the half-cutting step are performed in this order.

[0088] In the full-cut process, as shown in Fig. 10A, a full-cut groove G2 is formed by laser processing the workpiece film W. Specifically, the workpiece film W is irradiated with and scanned with laser light L2 (second laser light) from the film layer 30A side, thereby melting and cutting the film layer 30A, the adhesive layer 20A, and the film layer 10A in the laminated film X' to form the full-cut groove G2. The full-cut groove G2 is formed so as to follow a predetermined intended cutting line in the workpiece film W.

[0089] In the half-cut process, as shown in FIG. 10B, a half-cut groove G1 is formed by laser processing the workpiece film W. Specifically, the workpiece film W is irradiated with and scanned with a laser beam L1 (first laser beam) from the film layer 30A side, thereby melting the film layer 30A and the adhesive layer 20A in the laminated film X to form the half-cut groove G1. The half-cut groove G1 is formed along the full-cut groove G2 formed in advance. Specifically, the half-cut groove G1 is formed along the full-cut groove G2 on the inside of the full-cut groove G2 so as to contour the adhesive layer 20 within the area surrounded by the full-cut groove G2. The half-cut groove G1 and the full-cut groove G2 extend adjacent to each other in parallel, and are continuously connected in the extension direction in the adjacent direction. EXAMPLES

[0090] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples. In addition, the specific numerical values ​​of the blending amounts (contents), physical property values, parameters, etc. described below can be replaced with the upper limit (a numerical value defined as "equal to or less than") or lower limit (a numerical value defined as "equal to or more than") of the blending amounts (contents), physical property values, parameters, etc. corresponding to those described in the above-mentioned "Form for carrying out the invention".

[0091] Example 1 Preparation of Pressure-Sensitive Adhesive Composition First, a mixture containing 56 parts by mass of 2-ethylhexyl acrylate (2EHA), 34 parts by mass of lauryl acrylate (LA), 7 parts by mass of 4-hydroxybutyl acrylate (4HBA), 2 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 0.015 parts by mass of a photopolymerization initiator (product name "Omnirad 184", manufactured by IGM Resins) was irradiated with ultraviolet light (polymerization reaction) to obtain a prepolymer composition (polymerization rate is about 10%) (the prepolymer composition contains monomer components that have not undergone polymerization reaction). Next, 100 parts by mass of the prepolymer composition, 0.08 parts by mass of dipentaerythritol hexaacrylate (DPHA) as a multifunctional acrylate monomer, and 0.3 parts by mass of a silane coupling agent (product name "KBM-403", 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to obtain a pressure-sensitive adhesive composition C1.

[0092] Preparation process First, the adhesive composition C1 was applied onto the release-treated surface of the release liner (first film layer) to form a coating film. The release liner was a polyethylene terephthalate (PET) film (product name "Diafoil MRV#50", thickness 50 μm, manufactured by Mitsubishi Chemical Corporation) with one side treated for release with silicone. Next, the plasma-treated surface of a surface protection film (second film layer) with one side treated with plasma was attached to the coating film on the release liner. The surface protection film was a specified polyethylene terephthalate (PET) film with a thickness of 50 μm. In the plasma treatment, a plasma irradiation device (product name "AP-TO5", manufactured by Sekisui Kogyo Co., Ltd.) was used, and the voltage was set to 160 V, the frequency was set to 10 kHz, and the treatment speed was set to 5000 mm / min. Next, the coating film was irradiated with ultraviolet light from the surface protection film side to cure the coating film with ultraviolet light, and an adhesive layer with a thickness of 50 μm was formed. This resulted in a laminated film (release liner / adhesive layer / surface protection film). For ultraviolet irradiation, a black light was used as the irradiation light source, and the irradiation intensity was 5 mW / cm 2A carrier film was then attached to the laminate film. The carrier film was a single-sided adhesive film having an adhesive surface on one side in the thickness direction, and the adhesive surface of the carrier film was attached to the release liner side of the laminate film.

[0093] <Half-cut process> Next, the laminated film on the carrier film was laser processed to process the outer shape of the adhesive layer and the surface protective film on the release liner. Specifically, the laminated film was irradiated with and scanned with a first laser light from the surface protective film side to melt and cut the surface protective film and the adhesive layer so as to follow a predetermined first planned cutting line in the laminated film, forming a half-cut groove. In this process, a laser processing device (product name "LC500", Takei Electric Industry Co., Ltd.) was used, a CO2 laser with a wavelength of 9360 nm was used as the first laser light, the spot diameter of the laser light was 100 μm, the laser output was 20 W, the pulse frequency was 30 kHz, the cutting speed by the laser light was 500 mm / sec, and the number of scans (the number of half cuts in the half-cut process) was 1. In this process, an adhesive layer that was singulated into a predetermined planar shape was formed in the large-sized adhesive layer, and an individualized surface protective film (having the same planar shape as the singulated adhesive layer) was formed in the large-sized surface protective film.

[0094] <Full cut process> Next, the release liner was contoured by laser processing the laminated film on the carrier film. Specifically, the second laser light was irradiated and scanned from the surface protection film side onto the laminated film on the carrier film to form a full-cut groove that partially overlaps with the half-cut groove so as to follow a predetermined second cutting line outside the half-cut groove in the laminated film. The full-cut groove thus formed and the half-cut groove described above extend adjacent to each other in parallel, and are connected continuously in the extension direction in the adjacent direction. In this process, a laser processing device (product name "LC500", Takei Electric Industry Co., Ltd.) was used, a CO2 laser with a wavelength of 9360 nm was used as the second laser light, the spot diameter of the laser light was 100 μm, the laser output was 27 W, the pulse frequency was 30 kHz, the cutting speed by the laser light was 500 mm / sec, and the number of scans was 1. In addition, the separation distance between the first intended cutting line in the above-mentioned half cut process and the second intended cutting line in the full cut process (the spot center distance S as the shortest distance between the center position in a planar view of the irradiation spot of the first laser light and the center position in a planar view of the irradiation spot of the second laser light) was 101 μm.

[0095] In this manner, a laminated film (a laminated film having a pressure-sensitive adhesive layer) was produced in Example 1. The laminated film in Example 1 had a release liner, a pressure-sensitive adhesive layer, and a surface protective film in this order in the thickness direction, and the release liner had a thin extending end portion (extending end portion 12 shown in Figs. 1 and 2).

[0096] Example 2 A laminated film of Example 2 was produced in the same manner as the laminated film of Example 1, except for the following.

[0097] In the half-cut process, the surface protection film and the adhesive layer were melted by irradiation and scanning with the first laser light 11 times, with the melting points shifted by 20 μm in the direction intersecting the scanning direction, to form a half-cut groove with a width of about 300 μm (11 half-cuts). In the full-cut process, the second laser light was irradiated and scanned so as to trace the center of the width of the half-cut groove, to melt the release liner. The spot center distance S of the laser light irradiation spots in the half-cut process and full-cut process (the distance between the planar center position of the outermost irradiation spot of the first laser light in the half-cut process and the planar center position of the irradiation spot of the second laser light in the full-cut process) was 139 μm. The full-cut groove (G2) formed in this way and the above-mentioned half-cut groove (G1) extend adjacent to each other in parallel, as shown in FIG. 8, and are continuously connected in the extension direction in the adjacent direction. In the laminate film of Example 2, the extended end portion of the release liner is longer than that of the laminate film of Example 1.

[0098] Example 3 The laminated film of Example 3 was produced in the same manner as the laminated film of Example 2, except for the following. As an adhesive composition for forming an adhesive layer, adhesive composition C2 was prepared as described below, and adhesive composition C2 was used instead of adhesive composition C1 in the preparation process. The spot center distance S of the laser light irradiation spots in the half-cut process and full-cut process (the distance between the planar center position of the outermost irradiation spot of the first laser light in the half-cut process and the planar center position of the irradiation spot of the second laser light in the full-cut process) was 72 μm. The laminated film of Example 3 has a shorter extended end of the release liner than the laminated film of Example 2.

[0099] In preparing the adhesive composition C2, first, a mixture containing 45 parts by mass of 2-ethylhexyl acrylate (2EHA), 42 parts by mass of lauryl acrylate (LA), 2 parts by mass of n-butyl acrylate (BA), 4 parts by mass of 4-hydroxybutyl acrylate (4HBA), 7 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 0.015 parts by mass of a photopolymerization initiator (trade name "Omnirad 184", manufactured by IGM Resins) was irradiated with ultraviolet light (polymerization reaction) to obtain a prepolymer composition (polymerization rate: approximately 10%) (the prepolymer composition contains monomer components that have not undergone the polymerization reaction). Next, 100 parts by mass of the prepolymer composition, 0.08 parts by mass of dipentaerythritol hexaacrylate (DPHA) as a polyfunctional acrylate monomer, and 0.3 parts by mass of a silane coupling agent (product name "KBM-403", 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed together. In this manner, a pressure-sensitive adhesive composition C2 was obtained.

[0100] Comparative Example 1 A laminated film of Comparative Example 1 was produced in the same manner as the laminated film of Example 1, except that the following contour processing step was carried out instead of the above-mentioned half-cutting step and full-cutting step.

[0101] In the outer shape processing step of Comparative Example 1, the release liner, adhesive layer, and surface protection film on the carrier film were fully cut by laser processing the laminate film on the carrier film. Specifically, the surface protection film, adhesive layer, and release liner were melted and cut so as to follow a predetermined planned cutting line in the laminate film by irradiating and scanning the laminate film with laser light from the surface protection film side to form a full cut groove. In this step, a laser processing device (product name "LC500", Takei Electric Co., Ltd.) was used, a CO2 laser with a wavelength of 9360 nm was used as the laser light, the spot diameter of the laser light was 100 μm, the laser output was 27 W, the pulse frequency was 30 kHz, the cutting speed by the laser light was 500 mm / sec, and the number of scans was 1. In this step, a laminate film that was cut into a predetermined planar shape was formed in a large-sized laminate film.

[0102] The laminated film of Comparative Example 1 (laminated film having a pressure-sensitive adhesive layer) comprises a release liner, a pressure-sensitive adhesive layer, and a surface protective film in that order in the thickness direction, and the release liner has an extended end portion that is not thin.

[0103] Comparative Example 2 The laminate film of Comparative Example 2 was produced in the same manner as the laminate film of Example 1, except for the following. A press processing step was carried out instead of the half-cut step and full-cut step. Specifically, a press processing blade was inserted in the thickness direction from the surface protection film side to the carrier film into the laminate film on the carrier film prepared in the preparation step, thereby forming a laminate film (release liner / adhesive layer / surface protection film) with a predetermined shape in plan view. The press processing blade has a cutting edge with a blade angle of 30 degrees.

[0104] <Gel Fraction> The gel fraction of the pressure-sensitive adhesive layer in each of the laminate films of Examples 1 to 3 and Comparative Examples 1 and 2 was measured. Specifically, the measurement was as follows.

[0105] First, about 0.1 g (mass: W1 mg) of an adhesive sample was taken from the adhesive layer in the laminated film. Next, the adhesive sample was wrapped in a purse-like shape with a tetrafluoroethylene resin porous film (mass: W2 mg) having an average pore size of 0.2 μm, and the opening was tied with a kite string (mass: W3 mg) to obtain a package. As the tetrafluoroethylene resin porous film, a porous film (product name: "Nitoflon NTF1122") manufactured by Nitto Denko Corporation was used. Next, the package containing the adhesive sample was placed in a container with a volume of 50 mL, and the container was filled with ethyl acetate (one container was used for each package). After leaving this at 23°C for 7 days, the package was taken out of the container and dried at 130°C for 2 hours. Then, the mass (W4 mg) of the package was measured. Then, the gel fraction (mass%) of the adhesive layer was calculated by substituting the values ​​of W1 to W4 into the following formula. The values ​​are shown in Table 1.

[0106] Gel fraction (mass%) = [(W4-W2-W3) / W1] x 100

[0107] <Shear storage modulus> For the pressure-sensitive adhesive layer in each of the laminate films of Examples 1 to 3 and Comparative Examples 1 and 2, the dynamic viscoelasticity was measured.

[0108] First, a required number of samples for measurement were prepared for each adhesive layer. Specifically, a plurality of pieces of adhesive layer cut out from the adhesive layer of the laminated film were laminated together to prepare a sample sheet with a thickness of about 1.5 mm. Next, this sheet was punched out to obtain cylindrical pellets (diameter 7.9 mm) as the measurement samples.

[0109] Then, dynamic viscoelasticity measurements were performed on the measurement samples using a dynamic viscoelasticity measuring device (name: Advanced Rheometric Expansion System (ARES), manufactured by Rheometric Scientific). Specifically, the measurement samples were fixed to a parallel plate fixture of the device with a diameter of 7.9 mm, and then measurements were performed. In this measurement, the measurement mode was shear mode, the measurement temperature range was -40°C to 100°C, the heating rate was 5°C / min, and the frequency was 1 Hz. The shear storage modulus (kPa) at 25°C was read from the measurement results. The values ​​are shown in Table 1.

[0110] <Shape analysis> The shape of the adhesive layer in each laminate film of Examples 1 to 3 and Comparative Examples 1 and 2 was analyzed using a shape analysis laser microscope (product name "VK-X1000", manufactured by KEYENCE). Specifically, the thickness h1 of the main region of the release liner, the extension length d1 and minimum thickness h2 (thickness of the thinnest part) of the extension end of the release liner, the thickness h3 of the outer part, and the distance d2 between the outer end of the release liner and the inner end of the adhesive layer were measured using the same microscope (thicknesses h1 to h3, extension length d1, and distance d2 are shown in FIG. 2). The measurement results are shown in Table 1. The ratio of thickness h2 to thickness h1 (h2 / h1) is also shown in Table 1. The ratio of thickness h3 to thickness h2 (h3 / h2) is also shown in Table 1.

[0111] <Peel initiation force and peel force> For each of the laminated films in Examples 1 to 3 and Comparative Examples 1 and 2, the force required to peel the release liner (the peel initiation force and the subsequent peel force) was examined.

[0112] First, a test piece for measurement (approximately 50 mm short side × 100 mm long side) was cut out from the laminate film. Specifically, a test piece having a length of approximately 100 mm from the end of the laminate film and a width of 50 mm was cut out from the laminate film.

[0113] Next, the test piece was fixed to the fixing table of a tensile tester (product name "Autograph", manufactured by Shimadzu Corporation). Specifically, the surface protection film side of the test piece was attached to the fixing table via a strong double-sided adhesive tape.

[0114] Next, a gripping tape was attached to the short side of the extended end of the release liner of the test piece on the fixing table. The gripping tape had a strong adhesive surface, and the gripping tape was attached to the release liner of the test piece via the strong adhesive surface.

[0115] Next, a peel test was performed by peeling the release liner on the adhesive layer of the test piece from the adhesive layer using a tensile tester, and the force required for peeling was measured as peel strength. In this measurement, the measurement temperature was 25°C, the release liner was peeled off by pulling the gripping tape in the length direction of the test piece, the peel angle was 180°, the pulling speed was 300 mm / min, and the peel length was 80 mm. An example of a graph obtained by such a peel test is shown in Figure 11. In the graph of Figure 11, the horizontal axis represents the peel length (mm), the vertical axis represents the peel strength (N / 50 mm), and Fmax represents the maximum peel strength.

[0116] The peel initiation force F1 (N / 50 mm) and peel force F2 (N / 50 mm) determined by the above peel test are shown in Table 1. The ratio (F1 / F2) of peel initiation force F1 to peel force F2 is also shown in Table 1. Peel initiation force F1 is the maximum peel strength within a peel length of 20 mm when the release liner is peeled from the adhesive layer, and peel force F2 is the average peel strength within a peel length of 20 to 100 mm (where the peel strength is stable after passing the peel initiation force F1 at the start of peeling).

[0117] <End Blocking> The resistance to edge blocking was examined for each laminate film of Examples 1 to 3 and Comparative Examples 1 and 2. Specifically, first, 10 evaluation samples of substantially the same size were prepared for each laminate film, and the 10 evaluation samples were stacked to form a film bundle (first step). In the film bundle, the edges of the 10 laminate films were substantially flush with each other in the thickness direction. Next, the adhesive surface at the tip of a cylindrical rod (diameter 10 mm) having an adhesive surface at the tip was pressed from above against the laminate film located at the top of the film bundle, and then the rod was pulled up, and the number of laminate films lifted up with the rod was counted (second step). A trial consisting of the first step and the subsequent second step was performed 10 times for each film bundle. In the 10 trials, if the number of trials in which only one laminate film was lifted up with the rod was 10, it was evaluated as "excellent", if it was 6 to 9, it was evaluated as "fair", and if it was 5 or less, it was evaluated as "poor". The evaluation results are shown in Table 1.

[0118] [Table 1] [Explanation of symbols]

[0119] X Laminated film (Laminated film with adhesive layer) H Thickness direction D plane direction 10 Film (First Film) 11 Main area 12 Extended end 12a,12b surface 12c top 12p thinnest part 12q outer part 20 Adhesive layer 23,33 End face 30 Film (2nd Film) W Work Film 10A, 30A film layer 20A Adhesive layer D1 Flow direction D2 width direction

Claims

1. a pressure-sensitive adhesive layer having a first surface and a second surface opposite to the first surface; a first film in contact with the first surface; a second film in contact with the second surface, the first film has an extended end portion, the extended end portion extending outward beyond an end surface of the pressure-sensitive adhesive layer in a plane direction perpendicular to a thickness direction; The extended end portion has a surface that is flush with the end face, and the extended end portion has a pressure-sensitive adhesive layer that is thinner than a main region of the first film that contacts the pressure-sensitive adhesive layer.

2. The laminated film having a pressure-sensitive adhesive layer according to claim 1 , wherein the extension length of the extended end portion from the end face in the planar direction is 50 μm or more.

3. 2. The laminated film having a pressure-sensitive adhesive layer according to claim 1, wherein the extension length of the extended end from the end face in the planar direction is 500 μm or less.

4. 2. The laminated film having a pressure-sensitive adhesive layer according to claim 1, wherein a ratio of a minimum thickness of the extended end portion to a thickness of the main region portion is 0.3 or more.

5. 2. The laminated film having a pressure-sensitive adhesive layer according to claim 1, wherein the extended end portion has a thinnest portion and an outer portion that is outer than the thinnest portion in the planar direction, and the outer portion is thicker than the thinnest portion.

6. The laminated film having a pressure-sensitive adhesive layer according to claim 1 , wherein the pressure-sensitive adhesive layer has a shear storage modulus of 100 kPa or less at 25° C.

7. The laminate film having a pressure-sensitive adhesive layer according to claim 1 , wherein the pressure-sensitive adhesive layer has a gel fraction of 40% by mass or more and 80% by mass or less.

8. 8. A laminate film having a pressure-sensitive adhesive layer according to claim 1, wherein in a peel test in which the first film is peeled from the pressure-sensitive adhesive layer under conditions of 25°C, a peel angle of 180° and a tensile speed of 300 mm / min, the ratio of peel initiation force to peel force is 10 or less.

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