adhesive sheet

Abstract

To provide a pressure-sensitive adhesive sheet that has excellent designability while ensuring a conduction path for removing air bubbles.SOLUTION: Provided is a pressure-sensitive adhesive sheet, which includes an extensible film layer, a pressure-sensitive adhesive layer formed on one side of the extensible film layer, and a releasable sheet formed on the side of the adhesive layer opposite to the extensible film layer, and has a groove formed on the side of the adhesive layer opposite to the extensible film layer, and in which the groove terminates at the outer peripheral portion of the pressure-sensitive adhesive layer, or communicates with another groove that terminates at the outer peripheral portion of the pressure-sensitive adhesive layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet. [Background technology]

[0002] Conventionally, in pressure-sensitive adhesive sheets that can be attached to an adherend without using adhesive by virtue of a pressure-sensitive adhesive layer provided on the sheet, preventing the intrusion of air bubbles during adhesion has been an issue. In response to this, a pressure-sensitive adhesive sheet has been proposed in which convex portions are provided on the pressure-sensitive adhesive layer, making it possible to remove air bubbles from the voids in the convex portions (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-336017 Summary of the Invention [Problem to be solved by the invention]

[0004] However, providing voids in the adhesive layer causes unevenness on the surface of the adhesive sheet, which impairs the design.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a pressure-sensitive adhesive sheet that has excellent design properties while ensuring a conduction path for removing air bubbles. [Means for solving the problem]

[0006] In order to solve the above problems, an adhesive sheet according to one embodiment of the present invention comprises a stretchable film layer, an adhesive layer formed on one side of the stretchable film layer, and a peelable sheet formed on the side of the adhesive layer opposite the stretchable film layer, and has a groove portion formed on the side of the adhesive layer opposite the stretchable film layer, and the groove portion terminates at the outer periphery of the adhesive layer or is connected to another groove portion that terminates at the outer periphery of the adhesive layer. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to provide a pressure-sensitive adhesive sheet that has excellent design properties while ensuring a conduction path for removing air bubbles. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically showing one configuration example of a pressure-sensitive adhesive sheet according to a first embodiment of the present invention. [Figure 2] 1 is a perspective view schematically showing one configuration example of a printed resin film according to a first embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view schematically showing one configuration example of a pressure-sensitive adhesive sheet according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a pressure-sensitive adhesive sheet according to one embodiment of the present invention will be described with reference to the drawings. Here, the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. differ from the actual ones. Furthermore, the embodiment shown below exemplifies a configuration for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited to the materials, shapes, structures, etc. of the constituent parts described below. The technical idea of ​​the present invention is as set forth in the claims. Various modifications may be made within the scope of the appended claims.

[0010] First Embodiment (adhesive sheet) The basic configuration of the pressure-sensitive adhesive sheet according to the first embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view illustrating one configuration example of the pressure-sensitive adhesive sheet 1 according to the first embodiment of the present disclosure. As shown in Figure 1, an adhesive sheet 1 according to one embodiment of the present invention comprises a stretchable film layer 10 and an adhesive layer 15 formed on one side (hereinafter referred to as "back side 10b") of the stretchable film layer 10. A release sheet 18 is attached to the side of the adhesive layer 15 opposite the stretchable film layer 10 (hereinafter referred to as "back side 15b"). The adhesive sheet 1 is suitable for wallpaper, for example.

[0011] <Expandable film layer> The extensible film layer 10 includes a first base material layer 11, a second base material layer 13 disposed on the side of the first base material layer 11 opposite the pressure-sensitive adhesive layer 15, and a pattern layer 12 disposed between the first base material layer 5 and the second base material layer 6. The extensible film layer 10 is formed so as to have a hiding power of 0.8 or more based on JIS K 5600-4-1. While an example in which a surface protective layer 14 is disposed on the surface 13a of the extensible film layer 10 facing the second base material layer 13 will be described, the present invention is not limited to this configuration. For example, the surface protective layer 14 may not be provided.

[0012] (first base layer) The first base material layer 11 is a sheet-like member that, together with the second base material layer 13, forms the base of the adhesive sheet 1. Examples of materials that can be used for the first base material layer 11 include resins that have excellent heat resistance, fire resistance, and mechanical strength, such as polypropylene resin, acrylonitrile-butadiene-styrene copolymer, and polycarbonate. The thickness of the first base layer 11 is preferably 50 μm or more and 150 μm or less in order to provide the desired physical properties such as sufficient strength while also satisfying the required hiding power. When the thickness is 50 μm or more, the physical properties such as strength and hiding power are improved. When the thickness is 150 μm or less, other physical properties such as fire resistance are improved. The first base layer 11 preferably has a hiding ratio of 0.8 or more based on JIS K 5600-4-1. When the hiding ratio of the first base layer 11 is 0.8 or less, the pattern layer 12 and second base layer 13 having hiding properties may be used to form the extensible film layer 10 so that the hiding ratio is 0.8 or more.

[0013] (Second base layer) The second base layer 13 is a sheet-like member that, together with the first base layer 11, forms the base of the pressure-sensitive adhesive sheet 1. As with the film of the first base layer 11, the resin that constitutes the second base layer 13 may be, for example, polypropylene resin, acrylonitrile-butadiene-styrene copolymer, polycarbonate, or the like, from the viewpoints of heat resistance, cold resistance, and mechanical strength. In addition, the second base layer 13 has transparency that allows the picture layer 12 to be visible. The thickness of the second base layer 13 is preferably 50 μm or more and 100 μm or less in order to provide the desired sufficient elasticity and impact resistance while satisfying other physical properties such as fire resistance. In addition, in this example, an example in which the second base material layer 13 is provided will be described, but the present invention is not limited to this configuration. For example, the second base material layer 13 may not be provided as necessary.

[0014] (Picture layer) The picture layer 12 is a layer for decorating the surface side of the adhesive sheet 1 with a picture pattern. The picture layer 12 is formed by printing a picture pattern on the surface 11a of the first base material layer 11. A coating of printing ink is used. There are no particular limitations on the printing ink, as long as it meets the requirements for lightfastness, color development, and safety of the ingredients used, which are generally required for wallpaper. Safety requirements include, for example, materials that do not contain heavy metals or sulfur compounds as pigments or additives. The thickness of the pattern layer 12 may be any thickness that allows the desired design to be fully expressed, and is preferably in the range of, for example, 0.1 μm to 10 μm. In addition, in this example, an example in which the pattern layer 12 is provided on the surface 11a of the first base material layer 11 will be described, but the present invention is not limited to this configuration. For example, the pattern layer 12 may not be provided as necessary.

[0015] (Surface protective layer) The surface protective layer 14 is a layer for protecting the first base material layer 5 and the pattern layer 12. The surface protective layer 14 has transparency that allows the pattern layer 12 to be seen, and also has physical properties such as sufficient strength, stain resistance, and weather resistance required for protection. The surface protective layer 14 is formed, for example, by applying a coating agent containing a solvent such as methyl ethyl ketone, a polyurethane resin, and an isocyanate curing agent to the surface of the second base material layer 13 opposite the pattern layer 12 (hereinafter referred to as "surface 13a"), drying the coating, and then curing the coating by ultraviolet irradiation. Other resins that may be used for the surface protective layer 14 include acrylic resin-based coating agents. The basis weight of the surface protective layer 14 is set to 2.0 g / m2 in terms of high surface strength. 2 More than 7.0g / m 2 It is preferable to do the following:

[0016] Alternatively, the surface of the surface protective layer 14, which is the outermost layer of the pressure-sensitive adhesive sheet 1, may be embossed (by forming a concave-convex shape using an embossing plate) to form (impart) an embossed pattern. In this case, the embossed pattern formed on the surface of the surface protective layer 14 can provide a more three-dimensional feel to the touch. In the embossing process, for example, recesses having a depth of 15 μm or more may be formed by passing the pressure-sensitive adhesive sheet 1 between an embossing roll and a rubber back roll having a hardness of 50 degrees or more but less than 90 degrees, thereby forming a concave-convex shape. Examples of methods for measuring hardness include the measurement method specified in JIS K-6253. Examples of embossed patterns include wood grain vessel grooves, stone slab surface irregularities, cloth surface texture, matte finish, sand grain, hairline, and linear grooves. As described below, embossing may be omitted, and no embossed pattern may be formed.

[0017] <Adhesive layer> The adhesive layer 15 is a layer that imparts adhesiveness to the extensible film layer 10. The back surface 15b of the adhesive layer 15 is formed with concaves and convexes that match the shape of the printed resin film 17 (described later), and multiple grooves 16 are formed as recesses. Each groove 16 terminates at the outer periphery of the adhesive layer 15 or is connected to other grooves 16 that terminate at the outer periphery of the adhesive layer 15. This allows air trapped between the adhesive layer 15 and the adherend to escape to the surroundings when the adhesive sheet 1 is attached to the adherend. After the air escapes to the surroundings, the bottoms of the grooves 16 are brought into close contact with the surface of the adherend, allowing the grooves 16 to disappear. Furthermore, by bringing the bottoms of the grooves 16 into close contact with the surface of the adherend, impact resistance and cold resistance can be improved.

[0018] The cross-sectional shape of the grooves 16 may be, for example, a V-shape, a U-shape, a rectangle, or a trapezoid. The volume occupied by the grooves 16 is, for example, 1×10 per area of ​​a circle of the adhesive layer 15 having a diameter of 500 μm. 3 μm 3 The depth of the deepest part of the groove portion 16 is preferably 3 μm or more and 10 μm or less to prevent unevenness on the surface of the pressure-sensitive adhesive sheet 1 due to the conduction path for removing air bubbles. If the depth is 3 μm or more, air trapped between the pressure-sensitive adhesive layer 15 and the adherend can be suitably released, improving the air-release performance. On the other hand, if the depth is 10 μm or less, the impact resistance of the pressure-sensitive adhesive sheet 1 is improved.

[0019] A preferred method for forming the grooves 16 is, for example, to attach a release sheet 18 having recesses and projections for forming the grooves 16, thereby forming the grooves 16. Alternatively, for example, a method can be employed in which an adhesive is uniformly applied to the back surface 10b of the first base material layer 11 of the extensible film layer 10, and then the adhesive is embossed using a mold having recesses and projections for forming the grooves 16, thereby forming the grooves 16.

[0020] An acrylic pressure-sensitive adhesive made from acrylic acid or an acrylic acid ester is used as the adhesive composition constituting the adhesive layer 15. Examples of acrylic pressure-sensitive adhesives that can be used include those disclosed in U.S. Pat. Nos. 3,239,478, 3,935,338, 5,169,727, Reissued Patent No. 24906, 4,952,650, and 4,181,752. The adhesive composition can be applied by roll coating or knife coating, for example.

[0021] Furthermore, the thickness of the thickest part of the adhesive layer 15, i.e., the thickness of the part where the groove portion 16 does not exist, is preferably 20 μm or more after the adhesive composition has been applied and dried, in order to provide workability and sufficient adhesive strength while balancing the thickness with the printed resin film 17 described below. Furthermore, from the viewpoints of impact resistance and air-release performance, the maximum height difference of the pressure-sensitive adhesive layer 15 is preferably 3% to 50% of the thickness of the thickest part of the pressure-sensitive adhesive layer 15. When it is 3% or more, air trapped between the pressure-sensitive adhesive layer 15 and the adherend can be released, improving air-release performance. On the other hand, when it is 50% or less, irregularities of the conductive paths are not formed on the surface of the pressure-sensitive adhesive sheet 1, improving design properties.

[0022] <Removable sheet> The release sheet 18 is a sheet-like member that is attached to the pressure-sensitive adhesive layer 15. Examples of the release sheet 18 that can be used include a laminate in which a release layer mainly made of silicone resin or the like is laminated on the surface of an appropriate substrate such as a plastic film or paper, a polyolefin resin film such as a polyethylene film, and a polyethylene terephthalate resin film.

[0023] <Printed resin film> FIG. 2 is a perspective view of a schematic configuration example of a printed resin film according to the first embodiment of the present invention, viewed obliquely from above. As shown in FIG. 2, the printed resin film 17 is a convex portion formed on the surface 18a of the release sheet 18 facing the adhesive layer 15, and fits into the groove portion 16. The material constituting the printed resin film 17 is not particularly limited, as long as it has weak adhesion to the release sheet 18 and can print a pattern having continuous openings on the release sheet 18. Furthermore, the material constituting the printed resin film 17 is a material that can maintain the printed resin film 17 for a long period of time without being affected by the solvent, such as acrylic or toluene, of the adhesive composition constituting the adhesive layer 15. For example, the material constituting the printed resin film 17 can be a polyurethane resin mixed with a solvent, such as methyl ethyl ketone.

[0024] As a method for forming the printed resin film 17, for example, a method of applying the resin by gravure printing to form the printed resin film 17 can be used. Other printing methods that can be used include flexographic printing, offset printing, screen printing, rotary printing, etc. Also usable are a method of embossing the printed resin film 17 using a roller-shaped mold, and a method of forming the printed resin film 17 made of resin on the surface of a plastic film or the like using a roller-shaped mold and a fluid resin composition.

[0025] The printed resin film 17 is terminated at the outer periphery of the release sheet 18 in accordance with the shape of the groove 16 described above, or is connected to another printed resin film 17 that terminates at the outer periphery of the release sheet 18. 2, the printed resin film 17 is formed, for example, in a grid pattern on the release sheet 18. When the printed resin film 17 is formed in a grid pattern, it is preferable that the printed resin film 17 is arranged parallel to the longitudinal direction of the release paper at an inclination angle of 30° to 60°. Furthermore, the length of one side of the adhesive portion 25 provided between groove portions 16 in the adhesive layer 15 is preferably 2 mm to 30 mm. Furthermore, the width of the printed resin film 17 is preferably 1 mm to 15 mm. By forming the printed resin film 17 in a grid pattern, the adhesive sheet 1 can be adhered to the adherend without allowing air bubbles to get in. Furthermore, the adhesive sheet 1 can be peeled off without leaving any marks even after a long period of time has passed since it was adhered.

[0026] When the printed resin film 17 is formed in a grid pattern, the grooves 16 in the adhesive layer 15 are also formed in a grid pattern. As a result, the adhesive portions 25 provided between the grooves 16 in the adhesive layer 15 are formed in independent polygons (for example, quadrangles). More specifically, as shown in Fig. 2, the printed resin film 17 is formed in a grid pattern by being arranged at equal intervals and parallel to the longitudinal direction of the release sheet 18 at an inclination angle of 45°. The length of one side of the adhesive portion 25 is 4 mm, and the width of the printed resin film 17 is 2 mm. In this case, the adhesive portion 25 is formed in a square shape. Alternatively, the printed resin film 17 may be formed in a stripe shape, a T-shape, or the like.

[0027] The thickness of the printed resin film 17 is preferably 3 μm or more and 10 μm or less to prevent the formation of irregularities on the surface of the pressure-sensitive adhesive sheet 1 due to the conduction paths for removing air bubbles. If the thickness is 3 μm or more, air trapped between the pressure-sensitive adhesive layer 15 and the adherend can be efficiently released, improving air-release performance. On the other hand, if the thickness is 10 μm or less, irregularities due to the conduction paths are not formed on the surface of the pressure-sensitive adhesive sheet 1, improving design properties.

[0028] <Effects of the first embodiment> The adhesive sheet 1 according to this embodiment has the following effects. (1) The pressure-sensitive adhesive sheet 1 of this embodiment has grooves 16 on the surface 15b of the pressure-sensitive adhesive layer 15 opposite the extensible film layer 10. This configuration improves impact resistance and air bleeding performance.

[0029] (2) The pressure-sensitive adhesive sheet 1 of the present embodiment is formed so that the extensible film layer 10 has a hiding factor of 0.8 or more based on JIS K 5600-4-1. According to this configuration, the conducting passage for removing bubbles can be concealed, and a higher design quality can be achieved.

[0030] (3) In the adhesive sheet 1 of the present embodiment, the depth of the deepest part of the grooves 16 is formed to be 3 μm or more and 10 μm or less. This configuration allows air bubbles to be suitably removed while preventing the formation of irregularities on the surface of the adhesive sheet 1, thereby achieving a higher level of design.

[0031] Second Embodiment The pressure-sensitive adhesive sheet according to the second embodiment of the present disclosure will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view illustrating one configuration example of the pressure-sensitive adhesive sheet 1 according to the second embodiment of the present disclosure. The surface protection layer 14 of this embodiment differs from the surface protection layer 14 shown in Fig. 1 in that the embossing is omitted and no embossed pattern is applied. In Fig. 1, the same components as those shown in Fig. 1 are denoted by the same reference numerals. In the pressure-sensitive adhesive sheet 1 according to the second embodiment of the present disclosure, embossing of the surface protective layer 14 is omitted, thereby ensuring a conduction path for removing air bubbles and preventing the design from being impaired by the conduction path. At the same time, the efficiency of manufacturing the pressure-sensitive adhesive sheet can be improved. [Example]

[0032] [Example 1] First, a 30 μm thick colored polypropylene film (manufactured by Riken Technos, OW) with a hiding power of 0.7 based on JIS K 5600-4-1 was prepared as the first substrate layer. Subsequently, a design layer was formed by gravure printing onto the surface of the first substrate layer so as to cover the entire surface of the first substrate layer. An acrylic resin-based oil-based ink (manufactured by Toyo Ink Mfg. Co., Ltd., product name: V351UR-T series) was used as the printing ink. Subsequently, an 80 μm thick uncolored polypropylene film (manufactured by Prime Polymer Co., Ltd., CPS-DB) was laminated onto the top layer of the design layer as the second substrate layer. Subsequently, an acrylic resin-based coating agent (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., W-480E) was applied to the surface of the second substrate layer by gravure printing to form a surface protection layer. The application amount of the acrylic resin-based coating agent was 6.0 g / m2 in dry weight. 2 In this way, a stretchable film layer was produced. The hiding power of the stretchable film layer based on JIS K 5600-4-1 was set to 0.7.

[0033] Next, an acrylic pressure-sensitive adhesive (BPS6113, Toyo Ink Mfg. Co., Ltd.) was applied and dried on the backside of the extensible film layer using a coating machine to form a pressure-sensitive adhesive layer. The thickness of the thickest part of the pressure-sensitive adhesive layer after drying was 10 μm. Next, a 120 μm-thick laminated sheet was prepared as a release sheet. The laminated sheet used was a sheet (SHA80, San-A Kaken Co., Ltd.) in which a release layer mainly composed of silicone resin was laminated on top of a polypropylene film layer and a paper layer was laminated on the bottom of the polypropylene film layer. Next, an ether-based polyurethane resin (Sakata Inx Corporation, Sapiriah) was applied to the surface of the release sheet by gravure printing to form a printed resin film in a grid pattern. The thickness of the printed resin film after drying was 1 μm. Next, the release sheet was pressure-bonded to the pressure-sensitive adhesive layer. This formed multiple grooves on the backside of the pressure-sensitive adhesive layer. The depth of the deepest part of the groove (the maximum height difference of the adhesive layer) was 1 μm, that is, the ratio of the maximum height difference of the adhesive layer to the thickness of the thickest part of the adhesive layer was 10%. In this way, the pressure-sensitive adhesive sheet of Example 1 was produced.

[0034] [Example 2] The thickness of the printed resin film after drying was 3 μm. That is, the depth of the deepest part of the groove (the maximum height difference of the adhesive layer) was 3 μm. Accordingly, the ratio of the maximum height difference of the adhesive layer to the thickness of the thickest part of the adhesive layer was 30%. Otherwise, the adhesive sheet of Example 2 was produced using the same materials and procedures as Example 1.

[0035] [Example 3] The thickness of the printed resin film after drying was 10 μm. That is, the depth of the deepest part of the groove (the maximum height difference of the adhesive layer) was 10 μm. Accordingly, the ratio of the maximum height difference of the adhesive layer to the thickness of the thickest part of the adhesive layer was 100%. Otherwise, the adhesive sheet of Example 3 was produced using the same materials and procedures as Example 1.

[0036] [Example 4] The thickness of the thickest part of the adhesive layer after drying was 20 μm. Accordingly, the ratio of the maximum height difference of the adhesive layer to the thickness of the thickest part of the adhesive layer was 30%. Except for this, the adhesive sheet of Example 4 was produced using the same materials and procedures as in Example 1.

[0037] [Example 5] The hiding power of the first base layer based on JIS K 5600-4-1 was set to 0.8. Accordingly, the hiding power of the extensible film layer based on JIS K 5600-4-1 was also set to 0.8. A pressure-sensitive adhesive sheet of Example 5 was produced using the same materials and procedures as in Example 1 except for the above.

[0038] [Example 6] The adhesive sheet of Example 6 was produced using the same materials and procedures as in Example 1, except that the thickness of the first base layer was set to 50 μm.

[0039] [Example 7] The thickness of the first base layer was set to 150 μm, and other than that, the adhesive sheet of Example 7 was produced using the same materials and procedures as in Example 1.

[0040] [Example 8] The first substrate layer was changed from a 30 μm-thick colored polypropylene film to a 50 μm-thick uncolored polypropylene film (CPS-DB, manufactured by Prime Polymer Co., Ltd.). The formation of the second substrate layer was omitted. The density of the design layer was then adjusted to a hiding factor of 0.8 based on JIS K 5600-4-1 of the extensible film layer. The thickness of the thickest part of the adhesive layer after drying was then 20 μm. The thickness of the printed resin film after drying was also set to 3 μm. That is, the depth of the deepest part of the groove (the maximum height difference of the adhesive layer) was set to 3 μm. Accordingly, the ratio of the maximum height difference of the adhesive layer to the thickness of the thickest part of the adhesive layer was 1.5%. The adhesive sheet of Example 8 was otherwise produced using the same materials and procedures as in Example 1.

[0041] [Example 9] The first base layer was a colored polypropylene film with a hiding factor of 0.94 based on JIS K 5600-4-1. The formation of a pattern layer was omitted. Accordingly, the hiding factor of the extensible film layer based on JIS K 5600-4-1 was set to 0.94. Subsequently, the thickness of the thickest part of the adhesive layer after drying was set to 40 μm. Accordingly, the ratio of the maximum height difference of the adhesive layer to the thickness of the thickest part of the adhesive layer was 7.5%. The adhesive sheet of Example 9 was otherwise produced using the same materials and procedures as in Example 8.

[0042] [Example 10] The thickness of the printed resin film after drying was 10 μm. That is, the depth of the deepest part of the groove (the maximum height difference of the adhesive layer) was 10 μm. Accordingly, the ratio of the maximum height difference of the adhesive layer to the thickness of the thickest part of the adhesive layer was 50%. Otherwise, the adhesive sheet of Example 10 was produced using the same materials and procedures as in Example 8.

[0043] [Example 11] The first base layer was a 70 μm thick colored polypropylene film with a hiding power of 0.94 based on JIS K 5600-4-1. Accordingly, the extensible film layer had a hiding power of 0.94 based on JIS K 5600-4-1. Subsequently, the thickness of the thickest part of the adhesive layer after drying was 40 μm. Furthermore, the thickness of the printed resin film after drying was 3 μm. That is, the depth of the deepest part of the groove (maximum height difference of the adhesive layer) was 3 μm. Accordingly, the ratio of the maximum height difference of the adhesive layer to the thickness of the thickest part of the adhesive layer was 7.5%. A pressure-sensitive adhesive sheet of Example 11 was produced using the same materials and procedures as Example 1 except for the above.

[0044] [Comparative Example 1] The adhesive sheet of Comparative Example 1 was produced using the same materials and procedures as in Example 11, except that the formation of the grooves was omitted.

[0045] (evaluation) The pressure-sensitive adhesive sheets of Examples 1 to 11 and Comparative Example 1 obtained by the above-mentioned methods were subjected to a visual evaluation of the conductive paths, an evaluation of the surface irregularities, and an air-bleeding performance confirmation test.

[0046] [Visual confirmation and evaluation of conduction paths] After the test piece was attached to the SUS plate, it was immediately checked under a D65 light source whether the conductive path was visible or not, and the result was evaluated using the following four levels: ◎, ◯, △, ×. ◎: No conductive path is visible ○: The conduction path is almost invisible △: Conduction path is faintly visible ×: The entire conduction path is visible

[0047] [Surface roughness evaluation] After attaching the test piece to the SUS plate, the surface of the test piece was touched with a finger, and the state of surface irregularities was evaluated using the following four levels: ◎, ◯, △, ×. ⊚: The surface is completely free of irregularities and feels smooth. ◯: Almost no unevenness on the surface. △: Some parts of the surface feel uneven. ×: Irregularities are felt along the shape of the conductive path.

[0048] [Air bleeding performance confirmation test] The test piece was attached to the SUS plate so that air bubbles were trapped inside, and immediately after that, the air bubbles were removed using a squeegee. The surface condition of the test piece was then visually observed and rated using the following four levels: ◎, 〇, △, ×. ◎: Air bubbles are completely removed ○: Tiny air bubbles can be seen, but most of the air bubbles have been removed △: Several small bubbles can be seen, but most of the bubbles have been removed. ×: Air bubbles are not removed and many air bubbles remain

[0049] (Evaluation results) Table 1 below shows the configuration of the pressure-sensitive adhesive sheets of each Example and Comparative Example, as well as the results of the visual evaluation of the conductive paths, the evaluation of the surface irregularities, and the air-bleeding performance confirmation test for each Example and Comparative Example.

[0050] [Table 1]

[0051] As shown in Table 1, the evaluation results of Examples 1 to 11 and Comparative Example 1 show that when grooves are formed in the adhesive layer as in Examples 1 to 11, the adhesive layer has higher air-release performance than when no grooves are formed as in Comparative Example 1.

[0052] Furthermore, the evaluation results comparing Example 1 with Examples 5 to 7 showed that by setting the concealing ratio of the extensible film layer to 0.8 or more and the thickness of the first base material layer to 50 μm or more and 150 μm or less, the conductive path becomes invisible, improving the design.

[0053] Furthermore, the evaluation results comparing Example 1 with Examples 4, 6, and 7 showed that by making the thickness of the thickest part of the adhesive layer 20 μm or more and making the thickness of the first base layer 50 μm or more and 150 μm or less, unevenness on the surface of the adhesive sheet due to the conductive paths is prevented, thereby improving the design.

[0054] The pressure-sensitive adhesive sheet of the present invention is not limited to the above-described embodiments and examples, and various modifications are possible within the scope of the invention without impairing its features. [Explanation of symbols]

[0055] 1...Adhesive sheet 10...Extensible film layer 11...First base material layer 12...Picture layer 13...Second base material layer 14…Surface protective layer 15...Adhesive layer 16...Groove 17...Printed resin film 18...Removable sheet

Claims

1. an extensible film layer; a pressure-sensitive adhesive layer formed on one surface of the extensible film layer; a release sheet formed on the surface of the pressure-sensitive adhesive layer opposite to the extensible film layer; Equipped with a groove formed on the surface of the pressure-sensitive adhesive layer opposite to the extensible film layer; the groove portion terminates at the outer peripheral portion of the pressure-sensitive adhesive layer or communicates with another groove portion that terminates at the outer peripheral portion of the pressure-sensitive adhesive layer, a printed resin film provided by printing on the surface of the pressure-sensitive adhesive layer of the release sheet so as to fill the grooves; The thickness of the printed resin film is 10 μm or less, the release sheet comprises a paper layer, a polypropylene film layer formed on the paper layer, and a release layer formed on the polypropylene film layer and containing a silicone resin; The printed resin film is provided on the peelable layer, the printed resin film is formed in a grid pattern by first convex ridge portions extending in a first direction and second convex ridge portions extending in a second direction perpendicular to the first direction, the first direction or the second direction is inclined at an angle of 30° or more and 60° or less with respect to the longitudinal direction of the release sheet, the extensible film layer comprises a first base material layer, a second base material layer disposed on the side of the first base material layer opposite to the pressure-sensitive adhesive layer, and a pattern layer disposed between the first base material layer and the second base material layer; The thickness of the first base layer is 50 μm or more and 150 μm or less, The thickness of the second base layer is 50 μm or more and 100 μm or less, A pressure-sensitive adhesive sheet characterized in that the width of the printed resin film is within the range of 1 mm to 15 mm (excluding 1 mm).

2. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the printed resin film has a thickness of 3 [mu]m or more.

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