Resin letterpress adhesive sheet

Abstract

To provide an adhesive sheet for a resin relief printing plate which can prevent a cleaning liquid from being penetrated onto an attaching surface while preventing air bubbles from remaining on the attaching surface.SOLUTION: An adhesive sheet for a relief printing plate which is interposed between a resin relief printing plate and a carrier sheet or a drum cylinder, includes a base material sheet, and adhesive layers laminated on both surfaces of the base material sheet, wherein a recess to the outer peripheral edge of the adhesive layer is formed on the surface of the adhesive layer, the adhesive layer is plastically deformed by pressing force imparted to the adhesive layer, when larger pressing force than that in temporary bonding is imparted to the adhesive layer, a state in which the space in the recess disappears in at least the outer peripheral edge part of the adhesive layer is maintained.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an adhesive sheet for resin letterpress printing, which is attached to a resin letterpress printing plate such as a flexographic printing plate. [Background technology]

[0002] For example, in flexographic printing, a resin relief flexographic plate (printing plate) is attached to a printing cylinder for printing. The flexographic plate is attached to a carrier sheet via a double-sided adhesive sheet, and is attached to the printing cylinder by wrapping the carrier sheet around the printing cylinder. In some cases, the flexographic plate is directly attached to the circumferential surface of the printing cylinder.

[0003] If air bubbles remain on the adhesive surface when the adhesive sheet is attached to a flexographic plate, carrier sheet, etc., this may affect printing accuracy, etc., so air release grooves are sometimes provided in the adhesive layer of the adhesive sheet to make it less likely for air bubbles to form (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-9669 [Patent Document 2] Japanese Patent Application Publication No. 4-331152 Summary of the Invention [Problem to be solved by the invention]

[0005] After the printing is completed, the flexographic plate may be removed from the plate cylinder and then washed. However, if an air release groove is formed in the adhesive sheet, the cleaning liquid may enter the adhesion surface through the air release groove, which may weaken the adhesive force. In addition, ink may enter the air release groove during printing, which may weaken the adhesive force. If the adhesive force weakens, the flexographic plate may peel off or fall off. Furthermore, if the cleaning liquid or ink enters the air release groove, not only will the adhesive force be weakened, but the remaining cleaning liquid or ink may remain until the next printing, and the remaining liquid may flow out due to rotation during printing and adhere to the printed material, resulting in printing defects. In order to solve such problems, when attaching the flexographic plate to the carrier sheet, preventive measures such as attaching a sealant or waterproof tape to the periphery for the purpose of waterproofing, or heat welding the flexographic plate to the carrier sheet for the purpose of preventing peeling or falling off are taken, but this requires time and effort, which causes a problem of reduced work efficiency.

[0006] From this viewpoint, an object of the present invention is to provide an adhesive sheet for resin letterpress printing that can prevent air bubbles from remaining on the adhesion surface while preventing ink and cleaning liquid from penetrating into the adhesion surface. [Means for solving the problem]

[0007] The present invention, which solves the above-mentioned problems, is an adhesive sheet for resin letterpress, which is interposed between a resin letterpress and a carrier sheet or a body cylinder, and which comprises a base sheet and an adhesive layer laminated on each side of the base sheet, wherein a recess is formed on the surface of the adhesive layer reaching the outer peripheral edge of the adhesive layer, and wherein the adhesive layer is plastically deformed by a pressing force applied to the adhesive layer, and when a pressing force greater than that at the time of temporary adhesion is applied to the adhesive layer, a state in which the space within the recess has disappeared at least at the outer peripheral edge of the adhesive layer is maintained.

[0008] According to the present invention, even if air bubbles are caught in the adhesion surface when the adhesive sheet for resin letterpress is temporarily attached to a resin letterpress or a carrier sheet, the air bubbles are discharged to the outside through the recesses, so that the air bubbles can be prevented from remaining. Furthermore, when a pressing force greater than that during temporary attachment is applied to the adhesive layer, the space in the recesses disappears and this state is maintained, so that ink is less likely to mix with the adhesion surface, and when the carrier sheet to which the resin letterpress is attached is washed, the infiltration of washing water into the adhesion surface can be prevented. Effect of the Invention

[0009] The pressure-sensitive adhesive sheet for resin letterpress printing according to the present invention can prevent air bubbles from remaining on the adhesion surface, while preventing ink and cleaning liquid from penetrating into the adhesion surface. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view of an adhesive sheet for resin letterpress according to an embodiment. [Diagram 2] FIG. 2 is an enlarged plan view of the adhesive sheet for resin letterpress according to the embodiment. [Diagram 3] FIG. 4 is a diagram showing a cross-sectional shape of a groove. [Figure 4] 1A is a longitudinal sectional view showing a modified example of a groove, and FIG. 1B is a sectional view taken along the line AA of FIG. [Diagram 5] FIG. 2(a) is a schematic diagram showing a state in which a release paper is laminated on one side of a resin letterpress adhesive sheet, and FIG. 2(b) is a schematic diagram showing a state in which a release paper is laminated on both sides of a resin letterpress adhesive sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1, an adhesive sheet 10 for resin letterpress printing according to an embodiment of the present invention is interposed between a resin letterpress printing plate 20 and a carrier sheet 30. A flexographic printing plate is one type of the resin letterpress printing plate 20.

[0012] The adhesive sheet 10 for resin letterpress printing comprises a base sheet 1 and adhesive layers 2 and 3 laminated on both sides of the base sheet 1. A release paper (not shown) is attached to the adhesive sheet 10 for resin letterpress printing before use.

[0013] The base sheet 1 is a resin sheet. Suitable resins include polyethylene terephthalate (PET), polyester, polypropylene, softened polyvinyl chloride, etc. There is no restriction on the color of the base sheet or on the presence or absence of translucency. There is no restriction on the thickness of the base sheet, but when the base sheet is made of polyethylene terephthalate, the thickness is, for example, 10 to 40 μm, and preferably 20 to 30 μm.

[0014] The adhesive layers 2 and 3 have adhesiveness that allows them to be attached to adherends (substrate sheet 1, resin relief printing plate 20, carrier sheet 30, barrel cylinder, etc.). The adhesive strength of one adhesive layer 2 is set on the assumption that it will be attached to a resin relief printing plate 20. The adhesive strength of the other adhesive layer 3 is set on the assumption that it will be releasably attached to a carrier sheet 30. The adhesive strength of one adhesive layer 2 is greater than that of the other adhesive layer 3. In the following description, when the pressure-sensitive adhesive layers 2 and 3 are to be distinguished, one pressure-sensitive adhesive layer 2 will be referred to as the "strong pressure-sensitive adhesive layer 2" and the other pressure-sensitive adhesive layer 3 will be referred to as the "weak pressure-sensitive adhesive layer 3".

[0015] The strong adhesive layer 2 is made of, for example, an acrylic resin-based adhesive composition. An acrylic resin-based adhesive composition is preferable because the acrylic ester copolymer, which is an elastomer, itself has adhesiveness and can be used with adherends made of various materials. The base polymer of the strong adhesive layer 2 has a glass transition temperature (Tg) of about −50° C. and a molecular weight of 500,000 to 700,000.

[0016] Monomers other than the acrylic polymer may be contained in all monomer components for constituting the acrylic polymer that is the base polymer of the strong adhesive layer 2. For example, one containing an acrylic acid ester monomer as the main monomer and vinyl acetate (VAc) as another monomer may be mentioned. Furthermore, the polymer component contained in the acrylic resin-based pressure-sensitive adhesive composition may contain other polymers in addition to the acrylic polymer that is the base polymer, so long as they have the same effect as the acrylic polymer. The adhesive composition may contain a tackifier. The tackifier is not particularly limited as long as it improves adhesive strength, and examples thereof include tackifier resins such as aliphatic petroleum resins (C5 resins), aromatic petroleum resins (C9 resins), aliphatic / aromatic copolymer petroleum resins (C5 / C9 resins), aliphatic hydrocarbon resins, rosin resins, terpene resins, and coumarone-indene resins.

[0017] In addition to the base polymer, the acrylic resin-based adhesive composition may contain a curing agent (crosslinking agent). For example, those crosslinked with an isocyanate-based, epoxy-based, metal chelate, or other compound are preferred. By using the curing agent, the adhesive strength and cohesive force can be adjusted. Examples of the curing agent (crosslinking agent) include an isocyanate-based curing agent, an epoxy-based curing agent, a metal chelate-based crosslinking agent, an oxazoline-based crosslinking agent, and an aziridine-based crosslinking agent. The curing agent (crosslinking agent) may be used alone or in combination of two or more. The thickness of the strong adhesive layer 2 is, for example, 60 to 90 μm, and more preferably 70 to 80 μm. There is no limitation on the type of adhesive composition constituting the strong adhesive layer 2, and it may be selected from rubber-based adhesive compositions, silicone-based adhesive compositions, etc., depending on the material of the adherend.

[0018] The weak adhesive layer 3 is made of, for example, an acrylic resin-based adhesive composition. The base polymer of the weak adhesive layer 3 contains, for example, an acrylic acid ester copolymer, and may contain a tackifier within a range that does not impair the effects of the present invention. The acrylic acid ester copolymer is preferably, for example, a copolymer of an acrylic acid ester and vinyl acetate. The base polymer of the weak adhesive layer 3 has a glass transition temperature (Tg) of about -50°C and a molecular weight of 500,000 to 800,000. As with the strong adhesive layer 2, the entire monomer component of the weak adhesive layer 3 may contain a monomer other than an acrylic polymer. Furthermore, the polymer component may contain other polymers in addition to the acrylic polymer that is the base polymer. When a curing agent (crosslinking agent) is used, an isocyanate-based curing agent, an epoxy-based curing agent, a metal chelate-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, etc. The curing agent (crosslinking agent) may be used alone or in combination of two or more kinds. The thickness of the weak adhesive layer 3 is smaller than that of the strong adhesive layer 2, for example, 20 to 50 μm, and more preferably 30 to 40 μm. The thickness of the weak adhesive layer 3 is preferably half that of the strong adhesive layer 2 or less. There is no limitation on the type of adhesive composition constituting the weak adhesive layer 3, and it may be selected from rubber-based adhesive compositions, silicone-based adhesive compositions, etc., depending on the material of the adherend.

[0019] The resin letterpress adhesive sheet 10 in the embodiment has a total thickness of preferably 90 to 180 μm, more preferably 120 to 150 μm. As long as the total thickness of the resin letterpress adhesive sheet 10 is within the above range, the thickness of the weak adhesive layer 3 may be half or less than that of the strong adhesive layer 2, or may be half or more.

[0020] 2, recesses 4 are formed on the surface of the strong adhesive layer 2, reaching the outer periphery of the strong adhesive layer 2. In this embodiment, the recesses 4 are made up of a plurality of grooves 4a, 4b, 4c that intersect with one another. Although not shown in the figure, the same recesses 4 (grooves 4a, 4b, 4c) as those on the strong adhesive layer 2 side are also formed on the surface of the weak adhesive layer 3.

[0021] As shown in Fig. 3, the groove 4a has a triangular cross section. Although not shown and detailed description is omitted, the grooves 4b and 4c also have a triangular cross section. The maximum groove width D of the groove 4a is, for example, 20 to 100 μm. The depth H of the grooves 4a is, for example, 5 to 40 μm. The depth H of the grooves 4a on the strong adhesive layer 2 side may be the same as the thickness of the strong adhesive layer 2, but is preferably less than the thickness of the strong adhesive layer 2. The depth H of the grooves 4a on the weak adhesive layer 3 side may be the same as the thickness of the weak adhesive layer 3, but is preferably less than the thickness of the weak adhesive layer 3.

[0022] When the thickness of the strong adhesive layer 2 is taken as 1, the maximum groove width dimension D of the grooves 4a, 4b, 4c on the strong adhesive layer 2 side is, for example, 0.2 to 1.7, preferably 0.4 to 1.3, and the depth H is, for example, 0.05 to 0.7, preferably 0.1 to 0.5. Furthermore, when the thickness of the weak adhesive layer 3 is taken as 1, the maximum groove width dimension of the grooves 4a, 4b, 4c on the weak adhesive layer 3 side is, for example, 0.4 to 5.0, preferably 0.8 to 3.0, and the depth is, for example, 0.1 to 2.0, preferably 0.2 to 1.0.

[0023] If the cross-sectional area of ​​the grooves 4a, 4b, 4c is reduced, the internal spaces of the grooves 4a, 4b, 4c are more likely to disappear (be filled) by the pressing force applied to the adhesive layers 2, 3, but there is a possibility that more air bubbles will remain on the adhesion surface. On the other hand, if the cross-sectional area of ​​the grooves 4a, 4b, 4c is increased, fewer air bubbles will remain on the adhesion surface, but a larger pressing force will be required to eliminate the internal spaces of the grooves 4a, 4b, 4c. Therefore, as shown in Fig. 4(a)(b), it is preferable that at least some (or all) of the grooves 4a, 4b, and 4c are formed by connecting a groove with a small cross-sectional area (hereinafter referred to as "small groove 41") and a groove with a larger cross-sectional area than the small groove 41 (hereinafter referred to as "large groove 42") in the groove extension direction. The cross-sectional area of ​​the large groove 42 is, for example, 1.5 to 2.5 times, preferably 1.8 to 2.2 times, that of the small groove 41. It is preferable that 30 to 70% of the total length of one groove 4a (or groove 4b, 4c) is the small groove 41 and the remaining is the large groove 42. The same applies to the grooves 4b and 4c. In addition, the small grooves 41 and the large grooves 42 may be alternately connected in the groove extension direction to form the grooves 4a, 4b, and 4c, or the small grooves 41 and the large grooves 42 may be connected one by one in the groove extension direction to form the grooves 4a, 4b, and 4c.

[0024] The cross-sectional area of ​​the small groove 41 is, for example, 50 to 600 μm 2 and preferably 150 to 380 μm 2 , more preferably 190 to 290 μm 2 When the cross section of the small groove 41 is triangular, the maximum groove width dimension D of the small groove 41 is, for example, 20 to 60 μm, preferably 30 to 50 μm, and more preferably 35 to 45 μm, and the depth H of the small groove 41 is preferably equal to or less than the maximum groove width dimension D of the small groove 41, and is, for example, 5 to 20 μm, preferably 10 to 15 μm, and more preferably 11 to 13 μm. When the thickness of the strong adhesive layer 2 is taken as 1, the small grooves 41 formed in the strong adhesive layer 2 preferably have a maximum groove width D of 0.4 to 0.7 and a depth H of 0.1 to 0.2. When the thickness of the weak adhesive layer 3 is taken as 1, the small grooves 41 formed in the weak adhesive layer 3 preferably have a maximum groove width dimension of 0.8 to 1.4 and a depth of 0.2 to 0.4.

[0025] The cross-sectional area of ​​the large groove 42 is, for example, 150 to 1050 μm 2 and preferably 300 to 700 μm 2 , more preferably 430 to 530 μm 2If the maximum groove width dimension D of the large groove 42 is made larger than that of the small groove 41, a large pressing force may be required to eliminate the internal space of the large groove 42, and therefore it is preferable that the maximum groove width dimension D is equal to or smaller than (preferably the same as) the maximum width dimension of the small groove 41. When the cross section of the large groove 42 is triangular, the maximum groove width dimension D of the large groove 42 is, for example, 20 to 60 μm, preferably 30 to 50 μm, and more preferably 35 to 45 μm, and the depth H of the large groove 42 is preferably equal to or smaller than the maximum groove width dimension D of the large groove 42, and is, for example, 15 to 35 μm, preferably 20 to 28 μm, and more preferably 22 to 26 μm. When the thickness of the strong adhesive layer 2 is taken as 1, the large groove 42 formed in the strong adhesive layer 2 preferably has a maximum groove width D of 0.4 to 0.7 and a depth H of 0.2 to 0.4. Furthermore, when the thickness of the weak adhesive layer 3 is taken as 1, the large groove 42 formed in the weak adhesive layer 3 preferably has a maximum groove width dimension of 0.8 to 1.4 and a depth of 0.5 to 0.9.

[0026] As shown in Fig. 2, the first groove 4a and the second groove 4b are linear grooves in a plan view formed to connect two opposing edges of the strong adhesive layer 2. Adjacent first grooves 4a, 4a are formed to be parallel, and similarly, adjacent second grooves 4b, 4b are formed to be parallel. A single first groove 4a intersects with a plurality of second grooves 4b, and similarly, a single second groove 4b intersects with a plurality of first grooves 4a. The third groove 4c is a linear groove in a plan view formed to pass through the intersection of the first groove 4a and the second groove 4b. Adjacent third grooves 4c, 4c are formed to be parallel to each other.

[0027] In this embodiment, the region defined by the grooves 4a, 4b, and 4c has a triangular shape. The triangular region is a region that comes into contact with the adherend. When the triangular region is an isosceles triangle (including an equilateral triangle), the apex angle is less than 90 degrees, and preferably 50 to 70 degrees. When the maximum groove width dimension of the grooves 4a, 4b, and 4c is 1, the diameter of a circle (inscribed circle) inscribed in a triangle having a side that is the center line of the grooves 4a, 4b, and 4c (a straight line passing through the deepest part in this embodiment) is, for example, 2.5 to 32.5, preferably 5 to 11, and more preferably 6 to 10. In addition, if the diameter of the inscribed circle is increased (the interval between the grooves 4a, 4b, and 4c is increased), the adhesive strength is increased, but there is a possibility that more air bubbles will remain on the application surface. On the other hand, if the diameter of the inscribed circle is decreased (the interval between the grooves 4a, 4b, and 4c is narrowed), there is a possibility that fewer air bubbles will remain on the application surface, but the adhesive strength is decreased. Therefore, the diameter of the inscribed circle is preferably 250 to 650 μm.

[0028] When the grooves 4a, 4b, 4c include the small grooves 41, the diameter of the inscribed circle is preferably 450 μm or less. For example, when the maximum groove width dimension of the small grooves 41 is 40 μm, the diameter is preferably 280 to 440 μm (7 to 11 when the maximum groove width dimension of the small grooves 41 is 1), and more preferably 320 to 400 μm (8 to 10 when the maximum groove width dimension of the small grooves 41 is 1).

[0029] When the diameter of the inscribed circle is increased, it is preferable to increase the cross-sectional area of ​​the grooves 4a, 4b, and 4c so that a large number of bubbles can be discharged from one groove. For example, when the diameter of the inscribed circle exceeds 450 μm, the cross-sectional area of ​​the grooves 4a, 4b, and 4c is, for example, 300 to 2000 μm. 2 and preferably 700 to 1350 μm 2 , more preferably 825 to 1105 μm 2Therefore, when the cross section of the grooves 4a, 4b, and 4c is triangular, the maximum groove width dimension D of the grooves 4a, 4b, and 4c is, for example, 60 to 100 μm, preferably 70 to 90 μm, and more preferably 75 to 85 μm, and the depth H of the grooves 4a, 4b, and 4c is preferably equal to or less than the maximum groove width dimension D, and is, for example, 10 to 40 μm, preferably 20 to 30 μm, and more preferably 22 to 26 μm. In addition, when the diameter of the inscribed circle exceeds 450 μm and the cross section of the grooves 4a, 4b, and 4c is triangular, it is preferable that the diameter of the inscribed circle is 5 to 9, preferably 6 to 8, when the maximum groove width dimension of the grooves 4a, 4b, and 4c is 1. In the strong adhesive layer 2, when the diameter of the inscribed circle exceeds 450 μm and the cross section of the grooves 4a, 4b, 4c is triangular, it is preferable that when the thickness of the strong adhesive layer 2 is 1, the maximum groove width dimension D of the grooves 4a, 4b, 4c is 0.8 to 1.3 and the depth H is 0.2 to 0.5. In the weak adhesive layer 3, when the diameter of the inscribed circle exceeds 450 μm and the cross section of the grooves 4a, 4b, 4c is triangular, it is preferable that when the thickness of the weak adhesive layer 3 is 1, the maximum groove width dimension of the grooves 4a, 4b, 4c is 1.7 to 3.0 and the depth is 0.5 to 1.0.

[0030] The grooves 4a, 4b, 4c are formed by adhering embossed release papers 5, 6 (see FIG. 5) to the adhesive layers 2, 3. The release papers 5, 6 include a core sheet as a substrate, a resin sheet laminated on both sides of the core sheet, and a release agent layer coated on the surface of the resin sheet. The resin sheet is made of, for example, polyethylene or polyethylene terephthalate. The resin sheet has ridges formed thereon corresponding to the grooves 4a, 4b, 4c. The release agent layer is made of, for example, a silicone-based release treatment agent.

[0031] The method for producing the adhesive sheet 10 for resin letterpress printing includes a first step of forming the weak adhesive layer 3 and a second step of forming the strong adhesive layer 2.

[0032] In the first step, an adhesive composition that will become the weak adhesive layer 3 is first applied to one side (the upper side in FIG. 5(a)) of a release paper 5 having ridges formed on both sides, and the adhesive composition is then dried. At this point, the ridges on one side of the release paper 5 are transferred to the weak adhesive layer 3, forming a weak adhesive layer 3 with grooves 4a, 4b, and 4c. Next, one side (the lower side in FIG. 5(a)) of a base sheet 1 is bonded to the weak adhesive layer 3 to form an intermediate laminate consisting of the release paper 5, the weak adhesive layer 3, and the base sheet 1 laminated together, and the intermediate laminate is then wound up on a roller. In the second step, the intermediate laminate (release paper 5, weak adhesive layer 3, base sheet 1) is unwound from the roller, and an adhesive composition that will become the strong adhesive layer 2 is applied to the other surface (upper surface in FIG. 5(a)) of the base sheet 1 of the intermediate laminate, and the adhesive composition is dried. This forms a final laminate (see FIG. 5(a)) that includes the release paper 5, weak adhesive layer 3, base sheet 1, and strong adhesive layer 2. When the final laminate is then wound up on the roller, the convex ridges on the other surface (lower surface in FIG. 5(a)) of the release paper 5 are transferred to the strong adhesive layer 2, and grooves 4a, 4b, and 4c are formed in the strong adhesive layer 2.

[0033] In the second step, a strong adhesive layer 2 having grooves 4a, 4b, and 4c may be formed by coating one surface of a release paper (a release paper having a convex stripe formed on at least one surface) other than the release paper 5 used in the first step with an adhesive composition that will become the strong adhesive layer 2 and drying the adhesive composition. In this case, a laminate of the strong adhesive layer 2 and the release paper is overlaid on the other surface of the base sheet 1 of the intermediate laminate (release paper 5, weak adhesive layer 3, base sheet 1), and then the release paper covering the strong adhesive layer 2 is peeled off to form the final laminate shown in Fig. 5(a).

[0034] 5(b), release papers 5, 6 may be laminated on both sides of the resin letterpress pressure-sensitive adhesive sheet 10. In this case, release paper having convex stripes formed on at least one side is used. In the first step, an adhesive composition that will become the weak adhesive layer 3 is first applied to one surface of the release paper 5, and the adhesive composition is dried. At this point, the convex stripes on one surface of the release paper 5 are transferred to the weak adhesive layer 3, forming the weak adhesive layer 3 with the grooves 4a, 4b, and 4c. Next, one surface of the base sheet 1 is bonded to the weak adhesive layer 3 to form a first intermediate laminate consisting of the release paper 5, the weak adhesive layer 3, and the base sheet 1 laminated together, and the intermediate laminate is taken up on a roller. In the second step, an adhesive composition that will become the strong adhesive layer 2 is applied to one side of a release paper 6 that is different from the release paper 5 used in the first step, and the adhesive composition is dried to form a second intermediate laminate in which the release paper 6 is laminated to the strong adhesive layer 2. At this point, the convex stripes on one side of the release paper 6 are transferred to the strong adhesive layer 2, and a strong adhesive layer 2 having grooves 4a, 4b, and 4c is formed. Thereafter, a second intermediate laminate (strong adhesive layer 2, release paper 6) is attached to the other side of the base sheet 1 of the first intermediate laminate (release paper 5, weak adhesive layer 3, base sheet 1), forming a final laminate (see FIG. 5(b)) in which the release paper 5, weak adhesive layer 3, base sheet 1, strong adhesive layer 2, and release paper 6 are laminated.

[0035] When using the adhesive sheet 10 for resin letterpress printing, first, the strong adhesive layer 2 is attached to the bottom surface of the resin letterpress printing 20. Since the grooves 4a, 4b, and 4c are formed in the strong adhesive layer 2, even if air bubbles are trapped on the attachment surface, they are discharged to the outside through the grooves 4a, 4b, and 4c. Next, the resin letterpress printing 20 is temporarily attached to the carrier sheet 30 via the weak adhesive layer 3 of the adhesive sheet 10 for resin letterpress printing. Since the grooves 4a, 4b, and 4c are formed in the weak adhesive layer 3, even if air bubbles are trapped on the attachment surface, they are discharged to the outside through the grooves 4a, 4b, and 4c. If the attachment position of the resin letterpress printing 20 to the carrier sheet 30 is misaligned, the weak adhesive layer 3 is peeled off again to correct the attachment position.

[0036] After the resin relief plate 20 is temporarily attached to the carrier sheet 30 at a predetermined position, the resin relief plate 20 is pressed firmly against the carrier sheet 30, and a larger pressing force than that during temporary attachment is applied to the adhesive layers 2 and 3. The adhesive layers 2 and 3 are plastically deformed by the pressing force applied during attachment, and a state in which the spaces within the grooves 4a, 4b, and 4c have disappeared at least at the outer periphery of the adhesive layers 2 and 3 is maintained.

[0037] As described above, with the adhesive sheet 10 for resin letterpress printing, even if air bubbles are trapped on the adhesion surface, they are discharged to the outside through the grooves 4a, 4b, and 4c (recesses 4), preventing the air bubbles from remaining. In addition, according to the adhesive sheet 10 for resin letterpress printing, by applying a large pressing force to the adhesive layers 2, 3, the spaces in the grooves 4a, 4b, 4c disappear at least at the outer periphery of the adhesive layers 2, 3. Therefore, when the resin letterpress printing plate 20 and the carrier sheet 30 integrated with the adhesive sheet 10 for resin letterpress printing are washed, it is possible to prevent the infiltration of cleaning water into the adhesion surface. Ink is less likely to be mixed into the adhesion surface during printing. In this way, according to the adhesive sheet 10 for resin letterpress printing, it is possible to prevent the ink and cleaning liquid from infiltrating into the adhesion surface while preventing air bubbles from remaining on the adhesion surface, so that the adhesive force is less likely to be lost. In other words, according to the adhesive sheet 10 for resin letterpress printing, peeling or falling off of the resin letterpress printing plate 20 is less likely to occur, so that the occurrence of printing defects and machine failures can be suppressed.

[0038] Furthermore, when grooves 4a, 4b, and 4c are provided with small grooves 41 designed to make the grooves easy to crush and large grooves 42 designed to allow for the expulsion of air bubbles, it is possible to effectively prevent air bubbles from remaining on the adhesion surface while preventing ink and cleaning liquid from penetrating the adhesion surface.

[0039] The grooves 4a, 4b, and 4c may be formed of only small grooves 41 or only large grooves .

[0040] In this embodiment, the cross-sectional shape of the grooves 4a, 4b, and 4c is triangular, but it may be trapezoidal, rectangular, or semicircular, for example. In addition, in the present embodiment, the grooves 4a, 4b, and 4c extend in three directions, but the grooves may extend in two directions. That is, in the present embodiment, the area defined by the grooves 4a, 4b, and 4c has a triangular shape, but the area defined by the multiple grooves may have a quadrangle shape (a rhombus or a parallelogram). Further, in this embodiment, the grooves are illustrated as straight lines, but they may be curved lines or broken lines. [Explanation of symbols]

[0041] 10. Adhesive sheets for resin letterpress printing 1 Base sheet 2 Strong adhesive layer (adhesive layer) 3 Weak adhesive layer (adhesive layer) 4 Recess 4a,4b,4c groove 41 Small groove 42 Large groove 20 Resin letterpress 30 Career Sheet

Claims

1. An adhesive sheet for resin letterpress, which is interposed between a resin letterpress and a carrier sheet or a cylinder, A base sheet; and a pressure-sensitive adhesive layer laminated on each of both sides of the base sheet, a plurality of grooves extending to an outer periphery of the pressure-sensitive adhesive layer are formed on a surface of the pressure-sensitive adhesive layer; When the thickness of one of the pressure-sensitive adhesive layers is taken as 1, the maximum groove width dimension of the groove is 0.4 to 1.3 and the depth is 0.1 to 0.5, When the thickness of the other pressure-sensitive adhesive layer is taken as 1, the maximum groove width dimension of the groove is 0.8 to 3.0 and the depth is 0.2 to 1.0, The adhesive sheet for resin letterpress printing is characterized in that the adhesive layer undergoes plastic deformation due to a pressure applied to the adhesive layer, and when a pressure greater than that during temporary adhesion is applied to the adhesive layer, a state in which the space within the groove has disappeared is maintained at least at the outer peripheral edge portion of the adhesive layer.

2. The pressure-sensitive adhesive sheet for resin letterpress printing according to claim 1 , wherein one of the pressure-sensitive adhesive layers has a higher adhesive strength than the other of the pressure-sensitive adhesive layers.

3. The area defined by the plurality of grooves has a polygonal shape, 2. The pressure-sensitive adhesive sheet for resin letterpress printing according to claim 1, wherein when the maximum groove width dimension of the groove is 1, the diameter of a circle inscribed in a polygon having a center line as a side is 5 to 11.

4. An adhesive sheet for a resin letterpress, which is interposed between a resin letterpress and a carrier sheet or a cylinder, A base sheet; and a pressure-sensitive adhesive layer laminated on each of both sides of the base sheet, a plurality of grooves extending to an outer periphery of the pressure-sensitive adhesive layer are formed on a surface of the pressure-sensitive adhesive layer; The groove has a small groove and a large groove that are continuous in an extension direction, the cross-sectional area of ​​the large groove is greater than the cross-sectional area of ​​the small groove; The adhesive sheet for resin letterpress printing is characterized in that the adhesive layer undergoes plastic deformation due to a pressure applied to the adhesive layer, and when a pressure greater than that during temporary adhesion is applied to the adhesive layer, a state in which the space within the groove has disappeared is maintained at least at the outer peripheral edge portion of the adhesive layer.

5. 5. The pressure-sensitive adhesive sheet for resin letterpress printing according to claim 4, wherein the maximum width dimension of the large groove is equal to or smaller than the maximum width dimension of the small groove, and the depth of the large groove is greater than the depth of the small groove.

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