Base paper for release paper, release paper, and adhesive sheet

Abstract

To provide base paper for release paper, release paper and a pressure-sensitive adhesive sheet which can be used in many kinds of printing systems such as an LBP system and an inkjet system and suppress the occurrence of curling due to the printing of the pressure-sensitive adhesive sheet.SOLUTION: The present invention provides a raw paper 1 for release paper comprising a paper substrate 10 (A) and a coating agent layer 12 (B) in this order, wherein the coating agent layer 12 (B) contains at least one ingredient (b) selected from the group consisting of dextrins, polyamine resins, and starches, and the raw paper 1 for release paper has an air permeability of 180 seconds or less as determined in accordance with the JISP8117.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a base paper for release paper, a release paper, and an adhesive sheet. [Background technology]

[0002]

[0003] Pressure-sensitive adhesive sheets that are attached to various objects are composed of, for example, a release paper, an adhesive layer formed thereon, and a surface substrate. Conventionally, the paper substrate used in the release paper absorbs and desorbs moisture in response to changes in humidity in the surrounding environment, causing the release paper to curl, which in turn causes problems in the manufacturing process and leads to a deterioration in the quality of the pressure-sensitive adhesive sheet.

[0003] As an example of technology relating to such release paper, Patent Document 1 discloses a release paper having a structure in which a resin layer, a mica-containing layer, and a release layer are laminated in that order on at least one side of a paper support, and the paper support is made of paper having a Stockigt sizing degree of 60 seconds or more, an air permeability of 50 seconds or more, and a wet tensile strength of 1.6 kg / 15 mm or more. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 07-252799 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, many different recording methods have been put into practical use, and these are used to print characters, images, and the like on the surface of the surface substrate of pressure-sensitive adhesive sheets. Examples of printing methods include inkjet printing and laser beam printing (hereinafter sometimes referred to as LBP methods). Pressure-sensitive adhesive sheets printed using LBP methods are subjected to a heat treatment to fix the toner. This heat treatment also causes the release paper to absorb and desorb moisture, so LBP printing tends to cause the pressure-sensitive adhesive sheet to curl after printing. However, the pressure-sensitive adhesive sheet using the release paper of Patent Document 1 above cannot sufficiently suppress the curling of the pressure-sensitive adhesive sheet caused by LBP printing, leaving room for improvement.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a base paper for release paper, a release paper using the same, and an adhesive sheet which can be used in a variety of printing methods such as the LBP method and the inkjet method, and which suppresses curling due to printing on an adhesive sheet. [Means for solving the problem]

[0007] As a result of intensive research into achieving the above-mentioned object, the inventors have discovered that a base paper for release paper comprises, in this order, (A) a paper substrate and (B) a coating layer, wherein the (B) coating layer contains at least one component (b) selected from the group consisting of dextrin, polyamine resin, and starch, and the base paper for release paper has an air permeability of 180 seconds or less as determined in accordance with JIS P 8117, and have thus completed the present invention.

[0008] That is, the present invention is as follows.

[0009] (1) The base paper for release paper comprises, in this order, (A) a paper substrate and (B) a coating layer, wherein the (B) coating layer contains at least one component (b) selected from the group consisting of dextrin, polyamine resin, and starch, and the air permeability of the base paper for release paper determined in accordance with JIS P 8117 is 180 seconds or less. (2) The base paper for release paper according to (1), wherein the starch is at least one selected from the group consisting of phosphated starch, acetylated oxidized tapioca starch, and oxidized starch. (3) The dry adhesion amount of the component (b) in the coating agent layer (B) is 0.1 to 1.0 g / m 2 The base paper for release paper according to (1) or (2) above, (4) The paper substrate (A) is a release paper base paper according to (1) or (2), which has an air permeability determined in accordance with JIS P 8117 of 10 to 150 seconds. (5) The release paper base paper according to (1) or (2), wherein the minimum flexibility of the release paper base paper, measured in accordance with the Gurley method specified in JIS L 1096:2010 using a Gurley flexibility tester, is within the range of 0.10 to 0.35 mN. (6) The release paper comprises the base paper for release paper according to (1) or (2) and a (C) release agent layer, the (C) release agent layer, the (A) paper substrate, and the (B) coating agent layer in this order. (7) (6) A pressure-sensitive adhesive sheet comprising the release paper described above, (D) a pressure-sensitive adhesive layer, and (E) a paper substrate for image recording, the pressure-sensitive adhesive sheet comprising the (E) paper substrate for image recording, the (D) pressure-sensitive adhesive layer, the (C) release agent layer, the (A) paper substrate, and the (B) coating agent layer in this order. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a release paper base paper that can be used in a variety of printing methods such as the LBP method and the inkjet method, and that suppresses curling of the adhesive sheet when printed, as well as a release paper and an adhesive sheet using the same. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a base paper for release paper according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an example of a release paper according to this embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing an example of the pressure-sensitive adhesive sheet according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0013] In the drawings, the same elements are given the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

[0014] Furthermore, in this specification, terms with "abbreviation" attached indicate the meaning of the term excluding "abbreviation" within the scope of common technical knowledge of a person skilled in the art, and also include the meaning itself excluding "abbreviation."

[0015] Furthermore, unless otherwise specified, the term "sheet" in this specification also includes what is called a "film," etc. Similarly, the term "film" in this specification also includes what is called a "sheet," etc.

[0016] Furthermore, unless otherwise specified, in this specification, "(meth)acrylic" includes methacrylic and acrylic, and "(meth)acrylate" includes methacrylate and acrylate. For example, (meth)acrylic means methacrylic, acrylic, or both.

[0017] 1. Base paper for release paper

[0018] FIG. 1 is a cross-sectional view showing an example of a release paper base paper 1 according to this embodiment.

[0019] The release paper base paper 1 according to this embodiment is a release paper base paper 1 comprising, in this order, (A) a paper substrate 10 and (B) a coating layer 12, the (B) coating layer 12 containing at least one component (b) selected from the group consisting of dextrin, polyamine resin, and starch, and the release paper base paper 1 has an air permeability of 180 seconds or less as determined in accordance with JIS P 8117. An adhesive sheet using this release paper base paper 1 can suppress curling of the adhesive sheet during printing.

[0020] Unless otherwise specified, the "release paper base paper 1" referred to here is not necessarily limited to a two-layer configuration, as long as it includes (A) a paper substrate 10 and (B) a coating agent layer 12, in that order. It is also not limited to a configuration in which these two layers are in contact with each other. For example, it goes without saying that a configuration of three or more layers, with another layer interposed between these two layers, may be used, if necessary. However, it is preferable that no other layer is interposed between these two layers. In other words, it is preferable that the (A) layer and the (B) layer are in contact with each other.

[0021] This "release paper base paper 1" does not include a release agent layer, which will be described later. Furthermore, this "release paper base paper 1" does not include a sealing layer between the (A) paper substrate 10 and the release agent layer. The "release paper base paper 1" according to this embodiment can be suitably used as "release paper" by, for example, including a sealing layer and a release agent layer, etc., in this order, on the surface of the (A) paper substrate 10 of the release paper base paper 1 opposite the surface containing the (B) coating agent layer 12 (in this case, the release agent layer allows the paper to be used as release paper, rather than as release paper base paper 1). The above-mentioned "release paper" can be suitably used as an "adhesive sheet," for example, by including an adhesive layer and a paper substrate for image recording, etc., in this order, on the surface of the release agent layer.

[0022] The release paper base paper 1 according to this embodiment has an air permeability of 180 seconds or less as determined in accordance with JIS P 8117. From the viewpoint of further suppressing curling during printing of an adhesive sheet including the release paper base paper 1, the upper limit of this air permeability is preferably 120 seconds or less, more preferably 100 seconds or less. The lower limit of this air permeability is not particularly limited, but is preferably 10 seconds or more, more preferably 20 seconds or more. Note that, for example, when the release paper base paper 1 includes layers other than the (A) paper substrate 10 and the (B) coating agent layer 12, the air permeability of the release paper base paper 1 including these layers is measured and used as the air permeability of the release paper base paper 1 (however, these layers do not include the (C) release agent layer 16 and the sealing layer 14 shown in FIG. 2 described below).

[0023] In particular, the effects of this embodiment can be more effectively achieved in electrophotographic printing such as the LBP method, in which the adhesive sheet is subjected to high heat due to the thermocompression of toner during printing. For example, in electrophotographic printing such as the LBP method, the adhesive sheet tends to curl during printing. However, an adhesive sheet including the release paper base paper 1 according to this embodiment can effectively suppress curling even in such LBP printing. Therefore, it can be suitably used for LBP printing. Furthermore, in LBP printing, high-quality paper substrates (wooden paper) are often used as the paper substrate (surface substrate) for recording images on the adhesive sheet. However, since the release paper base paper 1 according to this embodiment has an air permeability within the above-mentioned range, curling due to printing can be effectively suppressed even when used as the release paper base paper 1 for an adhesive sheet including a wood-free paper substrate as the surface substrate. Therefore, it can be suitably used as the release paper base paper 1 for an adhesive sheet including a wood-free paper substrate as the surface substrate (however, the functions and effects according to this embodiment are not limited to these).

[0024] Furthermore, in this embodiment, the minimum flexibility of the release paper base paper 1, measured using a Gurley flexibility tester in accordance with the Gurley method specified in JIS L 1096:2010, is preferably within the range of 0.10 to 0.35 mN. The lower limit is more preferably 0.20 mN or more, and even more preferably 0.22 mN or more. The upper limit is more preferably 0.30 mN or less. When the minimum flexibility of the release paper base paper 1 is within the above range, curling of the pressure-sensitive adhesive sheet including the release paper base paper 1 during printing can be effectively suppressed.

[0025] The flexibility of the release paper base paper 1 is measured using a Gurley flexibility tester in accordance with the Gurley method specified in JIS L 1096:2010. However, the direction in which the flexibility of the release paper base paper 1 is measured is not particularly limited, and the direction in which the flexibility is minimum may be measured. The direction in which the flexibility is minimum is, for example, the direction (CD) perpendicular to the forming direction (MD). Therefore, the minimum flexibility of the release paper base paper 1 can be obtained, for example, by measuring the flexibility in the direction (CD) perpendicular to the forming direction (MD) of the release paper base paper 1.

[0026] Each component of the release paper base paper 1 will be described below.

[0027] ((A) Paper base material)

[0028] (A) The type of paper for the paper base material 10 is not particularly limited, but examples thereof include wood-free paper, glassine paper, and kraft paper. The paper base material 10 preferably contains pulp, for example. The pulp constituting the paper base material 10 is not particularly limited, but examples thereof include hardwood pulp and softwood pulp.

[0029] The hardwood pulp is not particularly limited, and examples thereof include virgin pulp and recycled paper pulp. The virgin pulp is preferably wood pulp. Examples of the virgin pulp that can be used include various known hardwood pulps, such as chemical pulps including bleached hardwood kraft pulp (LBKP), unbleached hardwood kraft pulp (LUKP), semi-bleached hardwood kraft pulp (LSBKP), and sulfite hardwood pulp, as well as mechanical pulps including stone ground pulp (SGP), pressed stone ground pulp (TGP), chemi-ground pulp (CGP), groundwood pulp (GP), and thermomechanical pulp (TMP). Among these, from the viewpoint of effectively improving surface smoothness, chemical pulps such as bleached hardwood kraft pulp (LBKP), unbleached hardwood kraft pulp (LUKP), semi-bleached hardwood kraft pulp (LSBKP), and hardwood sulfite pulp are preferred, and bleached hardwood kraft pulp (LBKP) is more preferred.

[0030] The softwood pulp is not particularly limited, and various known pulps can be used, including chemical pulps such as bleached softwood kraft pulp (NBKP), unbleached softwood kraft pulp (NUKP), semi-bleached softwood kraft pulp (NSBKP), and softwood sulfite pulp, and mechanical pulps such as stone ground pulp (SGP), pressed stone ground pulp (TGP), chemi-ground pulp (CGP), groundwood pulp (GP), and thermomechanical pulp (TMP).

[0031] The pulp content of the (A) paper base material 10 is not particularly limited, but is preferably 60 to 100% by mass. The lower limit is more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more. The upper limit is more preferably 98% by mass or less, and even more preferably 97% by mass or less.

[0032] Furthermore, the mass proportion of hardwood pulp in the pulp used in (A) paper base material 10 (hardwood pulp content / total pulp amount) is preferably 50 mass% or more. The lower limit is more preferably greater than 50 mass%, even more preferably 60 mass% or more, even more preferably 70 mass% or more, even more preferably greater than 80 mass%, and even more preferably 100 mass%. By having the mass proportion of hardwood pulp in the total pulp amount within the above range, the surface smoothness of the release paper base paper 1 is more effectively improved.

[0033] Furthermore, when the pulp constituting the (A) paper base material 10 contains softwood bleached kraft pulp (NBKP) and / or hardwood bleached kraft pulp (LBKP), the softwood bleached kraft pulp (NBKP) / hardwood bleached kraft pulp (LBKP) content ratio (NBKP content ratio to LBKP, pulp N / L ratio, mass ratio) is preferably 0 / 100 to 70 / 30, more preferably 0 / 100 to 20 / 80. This further effectively improves the surface smoothness of the release paper base paper 1.

[0034] The method for producing the (A) paper base material 10 is not particularly limited, and known methods can be used. For example, softwood pulp and hardwood pulp are dispersed in water in a predetermined mass ratio, and the dispersion is beaten to a predetermined degree in a beater to obtain a pulp slurry. Next, additives and the like are added to the obtained pulp slurry as desired. The prepared slurry is made into paper using a known papermaking machine such as a Fourdrinier papermaking machine, a cylinder papermaking machine, or a twin-wire papermaking machine, to obtain the (A) paper base material 10. The papermaking method is also not particularly limited, and either acidic papermaking or neutral papermaking can be selected.

[0035] (A) The basis weight of the paper substrate 10 is not particularly limited, but is preferably 35 to 100 g / m 2 The lower limit is preferably 50 g / m 2 The upper limit is 60 g / m 2It is more preferable that the basis weight is less than 1 / 2 the weight of the paper substrate 10. The basis weight is a value measured based on the basis weight testing method of JIS P 8124:2011. By keeping the basis weight within the above range, suitability for papermaking is further improved. In addition, the flexibility of the (A) paper substrate 10 can be controlled more effectively.

[0036] The thickness of the (A) paper substrate 10 is preferably 30 to 120 μm. The lower limit is more preferably 55 μm or more. The upper limit is more preferably 70 μm or less. When the thickness of the (A) paper substrate 10 is equal to or greater than the above-mentioned lower limit, the occurrence of wrinkles during the production of the release paper base paper 1 can be effectively suppressed. Also, the suitability for the cutting process in the label processing during the production of adhesive labels can be effectively improved. Furthermore, the flexibility of the (A) paper substrate 10 can be more effectively controlled. Also, when the thickness of the (A) paper substrate 10 is equal to or less than the above-mentioned upper limit, excessive rigidity can be effectively suppressed. This thickness can be measured in accordance with JIS P 8118:2014.

[0037] The beating degree of the (A) paper base material 10, as measured by the Schopper-Rigler method, is preferably 20 to 50°SR. The lower limit is more preferably 40°SR or higher. When the beating degree of the (A) paper base material 10 is equal to or higher than the above-mentioned lower limit, stable paper strength is more easily obtained, and paper breakage after papermaking can be more effectively prevented. Furthermore, when the beating degree of the (A) paper base material 10 is equal to or lower than the above-mentioned upper limit, pulp fibrillation can be more effectively suppressed, and penetration of the components forming the coating agent layer 12 and / or filling layer into the paper can be more effectively suppressed.

[0038] The (A) paper substrate 10 preferably has an air permeability of 10 to 150 seconds as determined in accordance with JIS P 8117. The upper limit is more preferably 120 seconds or less, and even more preferably 100 seconds or less. The lower limit of this air permeability is not particularly limited, but is more preferably 20 seconds or more. When the air permeability of the (A) paper substrate 10 is within the above range, curling due to printing of the pressure-sensitive adhesive sheet including the release paper base paper 1 can be more effectively suppressed.

[0039] (A) The paper substrate 10 may be subjected to various surface treatments such as heat treatment and corona discharge treatment in advance to enhance adhesion to each coating layer. The conditions for such surface treatments are not particularly limited as long as they achieve the effects of this embodiment, and suitable conditions can be selected as appropriate.

[0040] ((B) Coating layer)

[0041] The release paper base paper 1 according to this embodiment includes a (B) coating agent layer 12. The (B) coating agent layer 12 contains at least one component (b) selected from the group consisting of dextrin, polyamine resin, and starch. By including component (b), the air permeability of the release paper base paper 1 can be controlled, and as a result, curling due to printing of the pressure-sensitive adhesive sheet can be suppressed (however, the functions and effects according to this embodiment are not limited to these).

[0042] The dextrin preferably has a DE (Dextrose Equivalent) value of 10 to 40. Commercially available dextrins can be used. Specific examples of commercially available dextrins include Pinedex #2 (manufactured by Matsutani Chemical Industry Co., Ltd.; DE value 11), Pinedex #3 (manufactured by Matsutani Chemical Industry Co., Ltd.; DE value 25), Pinedex #4 (manufactured by Matsutani Chemical Industry Co., Ltd.; DE value 19), Pinedex #6 (manufactured by Matsutani Chemical Industry Co., Ltd.; DE value 40), MPD (manufactured by Matsutani Chemical Industry Co., Ltd.; DE value 25), Sandec #150 (manufactured by Sanwa Starch Industry Co., Ltd.; DE value 17), and Sandec #300 (manufactured by Sanwa Starch Industry Co., Ltd.; DE value 28). The DE value of the dextrin is preferably 20 to 40, and more preferably 25 to 40. In this embodiment, it is also preferable to use, for example, cyclic dextrin as the dextrin. The release paper base paper 1 containing the (B) coating agent layer 12 containing dextrin tends to be highly flexible (hard), and therefore can more effectively suppress curling caused by printing on the pressure-sensitive adhesive sheet (however, the functions and effects of this embodiment are not limited to these). These may be used alone or in combination of two or more.

[0043] The polyamine resin is preferably a compound having two or more amino groups or imino groups in the molecule, and is preferably a compound having no epoxy groups in the molecule. For example, commercially available products can be used as such polyamine resins. Specific examples of commercially available products include Sumirez (registered trademark) Resin SPI-102A (manufactured by Taoka Chemical Co., Ltd., modified amine-based resin) and PA series (manufactured by Seiko PMC Corporation, polyamide polyamine resin). Among these, it is more preferable to use Sumirez (registered trademark) Resin SPI-102A (manufactured by Taoka Chemical Co., Ltd., modified amine-based resin). These may be used alone or in combination of two or more.

[0044] The starch is preferably at least one selected from the group consisting of phosphated starch, acetylated oxidized tapioca starch, and oxidized starch. Among these, phosphated starch is more preferred. These may be used alone or in combination of two or more.

[0045] ((B) Content of Coating Layer)

[0046] The dry adhesion amount of the component (b) in the (B) coating agent layer 12 contained in the release paper base paper 1 according to this embodiment is 0.1 to 1.0 g / m 2 The lower limit is preferably 0.4 g / m 2 More preferably, it is 0.5 g / m or more. 2 More preferably, it is 0.7 g / m or more. 2 It is even more preferable that the dry adhesion amount of component (b) is equal to or greater than the above-mentioned lower limit, thereby effectively suppressing the generation of paper dust in the papermaking process of release paper base paper 1. When the dry adhesion amount of component (b) is equal to or less than the above-mentioned upper limit, the air permeability of release paper base paper 1 can be effectively reduced to 180 seconds or less, and as a result, curling of adhesive sheets containing release paper base paper 1 during printing can be effectively suppressed.

[0047] Furthermore, from the viewpoint of more effectively suppressing the generation of paper dust, it is preferable that component (b) contains at least one selected from the group consisting of dextrin and polyamine resin.

[0048] When the (B) coating layer 12 contains, as component (b), at least one selected from the group consisting of dextrin and polyamine resin, the mass ratio (b / B) of the dry adhesion amount of component (b) to the total dry adhesion amount of the (B) coating layer 12 is preferably 0.5 to 1.0. The lower limit of this mass ratio (b / B) is more preferably 0.7 or more, and even more preferably 0.9 or more. When the mass ratio (b / B) calculated as the dry adhesion amount is within this range, the air permeability of the release paper base paper 1 can be effectively reduced to 180 seconds or less, and as a result, curling due to printing of an adhesive sheet including the release paper base paper 1 can be more effectively suppressed. Furthermore, the generation of paper dust during the papermaking process can be more effectively suppressed.

[0049] The (B) coating layer 12 can be formed, for example, by applying a coating layer-forming composition prepared by dissolving component (b) in a solvent onto one surface of the (A) paper substrate 10 and drying the composition. The solvent may be selected appropriately depending on the form of component (b), and examples of the solvent include water. The application method is not particularly limited, and examples include a method using an appropriately selected coating device such as a blade coater, air knife coater, rod blade coater, bar blade coater, gravure coater, bar coater, multi-stage roll coater, roll coater, reverse roll coater, curtain coater, spray coater, gate roll coater, size press coater, or shim sizer.

[0050] The coating layer-forming composition may contain additives as needed. The additives are not particularly limited, but examples thereof include fillers such as kaolin, clay, silica, calcium carbonate, titanium oxide, and zinc oxide, dispersants, thickeners, defoamers, antifoaming agents, viscosity adjusters, lubricants, water-resistant agents, water retention agents, and colorants.

[0051] (B) The surface to be coated with the coating agent layer 12 may be smoothed, for example, by supercalendering, which further improves the sealing effect and stiffening effect.

[0052] 2. Release paper

[0053] FIG. 2 is a cross-sectional view showing an example of the release paper 2 according to this embodiment.

[0054] The release paper 2 according to this embodiment includes a release paper base paper 1 and a (C) release agent layer 16, and preferably includes the (C) release agent layer 16, the (A) paper substrate 10, and the (B) coating agent layer 12, in this order. Unless otherwise specified, the "release paper 2" herein refers to a paper that includes the (C) release agent layer 16, the (A) paper substrate 10, and the (B) coating agent layer 12, in this order. The release paper 2 according to this embodiment preferably includes the (C) release agent layer 16 on the surface of the (A) paper substrate 10 of the release paper base paper 1, opposite the surface including the (B) coating agent layer 12. Furthermore, the release paper 2 according to this embodiment is not necessarily limited to this three-layer configuration. For example, it may, of course, be configured to have four or more layers, with additional layers interposed between each layer, as needed.

[0055] Below, we will explain each of the components of the release paper 2. It goes without saying that the release paper base paper 1 included in the release paper 2 can appropriately adopt the above-mentioned components and configurations.

[0056] ((C) Release agent layer)

[0057] The release agent contained in (C) release agent layer 16 is not particularly limited, but examples thereof include silicone-based resins, fluorine-based resins, alkyd resins, long-chain alkyl resins, various waxes, etc. Among these, from the viewpoint of excellent releasability, the release agent is preferably a silicone-based resin.

[0058] Examples of silicone resins include homopolymers or copolymers of trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, diphenyldichlorosilane, phenyltrichlorosilane, methylvinyldichlorosilane, etc. These may be used alone or in combination of two or more.

[0059] The silicone resin may be used in any of the solvent-based, solventless, and emulsion-based forms, but the emulsion and solventless types are preferred.

[0060] The coating amount (dry adhesion amount) of the coating liquid containing the release agent is 0.4 to 3.0 g / m 2 The lower limit is preferably 0.6 g / m 2 More preferably, it is 0.8 g / m or more. 2 The upper limit is 2.0 g / m 2 More preferably, it is 1.5 g / m or less. 2 By controlling the coating amount within this range, it is possible to provide the release paper 2 with a release force that is more suitable for the release paper 2.

[0061] The thickness of the (C) release agent layer 16 is preferably 0.01 to 10 μm, more preferably 0.1 μm or more as the lower limit, and more preferably 5 μm or less as the upper limit.

[0062] The (C) release agent layer 16 can be formed, for example, by applying and heating to harden a coating liquid containing the release agent described above to a portion of the surface of the release paper base paper 1. The application method is not particularly limited, but can be, for example, a method of applying the coating using an appropriately selected coating device such as a blade coater, air knife coater, rod blade coater, bar blade coater, gravure coater, bar coater, or multi-stage roll coater.

[0063] Furthermore, the release paper 2 according to this embodiment preferably further comprises a filling layer 14 between the (A) paper substrate 10 and the (C) release agent layer 16, for the purposes of preventing the release agent from penetrating into the (A) paper substrate 10 when the release agent is applied and forming a (C) release agent layer 16 on the surface of the (A) paper substrate 10. By providing the filling layer 14, it is possible to effectively inhibit the penetration of the release agent into the (A) paper substrate 10 and effectively improve the releasability of the (C) release agent layer 16.

[0064] The filler layer 14 is not particularly limited, and any suitable material usable in the field of coated paper, etc., can be used as appropriate. Examples of binder resins for forming the filler layer 14 include polyvinyl alcohol-based resins such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, ethylene copolymer polyvinyl alcohol, acetoacetylated polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, olefin-modified polyvinyl alcohol, nitrile-modified polyvinyl alcohol, pyrrolidone-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, and other modified polyvinyl alcohols; (meth)acrylic resins such as methyl methacrylate-butadiene copolymers, copolymers of (meth)acrylic acid and monomer components copolymerizable with (meth)acrylic acid (excluding olefins); styrene-based resins such as styrene-maleic anhydride copolymers, styrene-butadiene copolymers, and styrene-acrylic copolymers; and resins such as polyamide resins, silicone-based resins, petroleum resins, terpene resins, ketone resins, and coumarone resins. Examples of the sealing layer 14 include layers containing cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and acetyl cellulose; starches such as oxidized starch, etherified starch, and esterified starch; casein, gum arabic, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic acid ester, polyvinyl butyral, polystyrose, and copolymers thereof; dextrin, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, and the like.

[0065] Among these, the filling layer 14 preferably contains at least one selected from the group consisting of polyvinyl alcohol resins, starches, and styrene resins. The filling layer 14 more preferably contains at least one selected from the group consisting of polyvinyl alcohol resins (fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol), oxidized starch, and styrene copolymers (styrene-maleic anhydride copolymer, styrene-butadiene copolymer, styrene-acrylic copolymer, etc.). These may be used alone or in combination of two or more.

[0066] Furthermore, the filling layer 14 may contain, as necessary, various commonly used auxiliary agents such as kaolin, clay, silica, other inorganic pigments, sizing agents, water-resistant agents, water-repellent agents, dyes, surfactants, dispersants, thickeners, water-retaining agents, antifoaming agents, water-resistant agents, dyes, fluorescent dyes, and crosslinking agents.

[0067] Among these sealing layers 14, the sealing layer 14 is more preferably a laminate of clay and polyvinyl alcohol resin (clay / polyvinyl alcohol resin) or polyvinyl alcohol resin, from the viewpoint of more effectively suppressing the penetration of the (C) release agent layer 16 into the (A) paper substrate 10. The thickness of the sealing layer 14 is not particularly limited, but is, for example, about 0.5 to 50 μm.

[0068] The release paper 2 according to this embodiment may be configured to include only one (single) filling layer 14, or may be configured to include multiple filling layers 14. When the release paper 2 according to this embodiment includes multiple filling layers 14, these multiple layers may be the same as or different from one another, and the types and configurations of these multiple layers are not particularly limited. For example, multiple filling layers 14 may be provided when it is desired to more effectively suppress the penetration of the release agent into the substrate or when it is desired to more effectively maintain the surface smoothness of the (C) release agent layer 16. Usually, when multiple filling layers 14 are included, it is more preferable that the number of layers is two or three.

[0069] The release paper 2 described above has the effect of at least effectively suppressing curling due to printing, and from the viewpoint of making effective use of this feature, a suitable application of the release paper 2 is, for example, protection of the adhesive layer of adhesive sheets, adhesive tapes, labels, etc. (protection of the adhesive surface of adhesive products). For example, conventional adhesive sheets and the like tend to be prone to problems such as curling due to printing, but the release paper 2 according to this embodiment can effectively suppress curling due to printing, as described above. This is particularly suitable when using high-quality paper as the material for the adhesive sheet described below.

[0070] 3. Adhesive sheet

[0071] FIG. 3 is a cross-sectional view of a first embodiment of the adhesive sheet 3 according to the present embodiment.

[0072] The pressure-sensitive adhesive sheet 3 according to the present embodiment preferably includes the release paper 2 described above, a (D) adhesive layer 18, and a (E) paper substrate 20 for image recording. The (D) adhesive layer 18 is preferably formed, for example, on at least a portion of the surface of the (E) paper substrate 20 for image recording and / or the surface of the (C) release agent layer 16. The pressure-sensitive adhesive sheet 3 preferably includes, in this order, the (E) paper substrate 20 for image recording, the (D) adhesive layer 18, the (C) release agent layer 16, the (A) paper substrate 10, and the (B) coating agent layer 12. The pressure-sensitive adhesive sheet 3 can be suitably used by, for example, laminating the (E) paper substrate 20 for image recording to the surface of the (C) release agent layer 16 of the release paper 2 described above via the (D) adhesive layer 18. The pressure-sensitive adhesive sheet 3 according to the present embodiment is not necessarily limited to this five-layer configuration. Needless to say, a configuration of six or more layers, with additional layers interposed between the individual layers, may be used as needed. For example, the pressure-sensitive adhesive sheet 3 shown in FIG. 3 has a six-layer structure, further including a sealing layer 14 between (A) a paper substrate 10 and (C) a release agent layer 16.

[0073] Below, we will explain each component of the adhesive sheet 3. It goes without saying that the release paper base paper 1 and release paper 2 included in the adhesive sheet 3 can appropriately adopt the above-mentioned components and configurations.

[0074] ((D)Adhesive layer)

[0075] The adhesive contained in (D) adhesive layer 18 is not particularly limited, but examples thereof include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, epoxy-based adhesives, polyester-based adhesives, urethane-based adhesives, polyolefin-based adhesives, and vinyl ether-based adhesives. The adhesive may also be a solvent-free adhesive such as a solvent-based adhesive, emulsion-based adhesive, or hot-melt-based adhesive, or an energy ray-curable adhesive that hardens upon irradiation with energy rays to become removable. Furthermore, the adhesive may contain, as needed, a crosslinking agent, a tackifier, a softener, an antioxidant, a filler, or a colorant such as a dye or pigment.

[0076] The thickness of (D) pressure-sensitive adhesive layer 18 is not particularly limited, but is preferably, for example, 1 to 100 μm. For example, when a thinner pressure-sensitive adhesive sheet 3 is desired, the thickness of (D) pressure-sensitive adhesive layer 18 can be reduced to 50 μm or less in a preferred embodiment, to 20 μm or less in a more preferred embodiment, and to 15 μm or less in an even more preferred embodiment. Even when the thickness of pressure-sensitive adhesive layer 18 is thus thin, the pressure-sensitive adhesive sheet 3 according to this embodiment can be expected to satisfy the required properties.

[0077] ((E) Paper substrate for image recording)

[0078] The (E) image recording paper substrate 20 is not particularly limited, but is preferably, for example, fine paper, coated paper, art paper, synthetic paper, etc., and more preferably, fine paper. Pulp, for example, can be used for the (E) image recording paper substrate 20. Further, such (E) image recording paper substrate 20 may, for example, contain wood pulp and a filler.

[0079] The wood pulp is not particularly limited, but examples thereof include chemical pulp and mechanical pulp of softwood or hardwood. The wood pulp preferably contains LBKP (hardwood bleached kraft pulp) in terms of texture and appearance. The composition ratio of NBKP (softwood bleached kraft pulp) to LBKP is preferably 0:100 to 20:80, more preferably 0:100 to 10:90, by mass.

[0080] Furthermore, if desired, various fibers can be mixed with the wood pulp, such as recycled paper pulp, non-wood pulp such as hemp or cotton, synthetic pulp made from polyethylene, polypropylene, or other raw materials, organic fibers such as acrylic fiber, rayon fiber, phenol fiber, polyamide fiber, and polyester fiber, and inorganic fibers such as glass fiber, carbon fiber, and alumina fiber.

[0081] The filler is not particularly limited, but examples thereof include mineral fillers such as talc, kaolin, clay, calcined kaolin, terramikaolin, calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, magnesium sulfate, magnesium silicate, calcium sulfate, calcium silicate, white carbon, aluminosilicate, silica, sericite, bentonite, and smectite, as well as organic synthetic fillers such as polystyrene resin microparticles, urea-formalin resin microparticles, and hollow microparticles. Fillers contained in waste paper, broken paper, and the like can also be recycled and reused. One type of filler may be used alone, or two or more types may be used in combination. The content of the filler is not particularly limited, but is preferably 0.5 to 20 parts by mass, and more preferably 3 to 15 parts by mass, per 100 parts by mass of the pulp raw material.

[0082] (E) In addition to the above-mentioned pulp and fillers, various conventionally used internal papermaking aids such as anionic, nonionic, cationic, or amphoteric retention aids, drainage aids, paper strength agents, and internal sizing agents can be appropriately selected and used as needed for the image-recording paper substrate 20, provided that the desired effects of this embodiment are not impaired. Furthermore, internal papermaking aids such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, and slime control agents can also be appropriately added depending on the application of the PSA sheet 3.

[0083] The method for producing the (E) image-recording paper substrate 20 is not particularly limited, and any known method may be used. For example, softwood pulp and hardwood pulp are dispersed in water in a predetermined mass ratio, and the dispersion is beaten to a predetermined degree using a beater to obtain a pulp slurry. Next, a filler and, if desired, additives are added to the obtained pulp slurry. The prepared slurry is made into paper using a known papermaking machine such as a Fourdrinier papermaking machine, a cylinder papermaking machine, or a twin-wire papermaking machine, to obtain the (E) image-recording paper substrate 20. The papermaking method is also not particularly limited, and either acidic or neutral papermaking can be selected.

[0084] (E) The basis weight of the paper substrate 20 for image recording is 35 to 150 g / m 2 The lower limit is preferably 50 g / m 2 The upper limit is 90 g / m 2 It is more preferable that the basis weight is less than 1 / 2 lb. This basis weight is a value measured based on the basis weight testing method of JIS P 8124:2011. By keeping the basis weight within the above range, the suitability for papermaking of (E) the paper substrate 20 for image recording can be further improved. In addition, the flexibility of (E) the paper substrate 20 for image recording can be effectively controlled.

[0085] The thickness of the (E) image-recording paper substrate 20 is preferably 30 to 180 μm. The lower limit is more preferably 50 μm or more. The upper limit is more preferably 100 μm or less. When the thickness of the (E) image-recording paper substrate 20 is equal to or greater than the above-mentioned lower limit, the occurrence of wrinkles during the production of the (E) image-recording paper substrate 20 can be effectively suppressed. Furthermore, when an adhesive label is produced from the adhesive sheet 3, the suitability for die-cutting in label processing can be effectively improved. Furthermore, the flexibility of the (E) image-recording paper substrate 20 can be effectively controlled. Furthermore, when the thickness of the (E) image-recording paper substrate 20 is equal to or less than the above-mentioned upper limit, excessive rigidity can be effectively suppressed. This thickness can be measured in accordance with JIS P 8118:2014.

[0086] The (E) image-recording paper substrate 20 preferably has an air permeability of 10 to 6000 seconds as determined in accordance with JIS P 8117. The upper limit is more preferably 1000 seconds or less, and even more preferably 300 seconds or less. The lower limit is not particularly limited, but is more preferably 20 seconds or more. When the (E) image-recording paper substrate 20 has an air permeability within the above range, curling of the pressure-sensitive adhesive sheet 3 due to printing can be more effectively suppressed.

[0087] Furthermore, the air permeability of the (E) image-recording paper substrate 20 and that of the release paper base paper 1 are preferably approximately the same, but may be different. The difference in air permeability between the release paper base paper 1 and the (E) image-recording paper substrate 20 is preferably 180 seconds or less, more preferably 120 seconds or less, even more preferably 100 seconds or less, even more preferably 90 seconds or less, even more preferably 80 seconds or less, and even more preferably 70 seconds or less. When the pressure-sensitive adhesive sheet 3 is heated by the heat during printing, moisture is released from the surfaces of the release paper base paper 1 and the (E) image-recording paper substrate 20. By keeping the difference in air permeability within the above-mentioned range, the difference in the amount and / or speed of moisture release from these surfaces can be effectively reduced. As a result, curling caused by printing of the pressure-sensitive adhesive sheet 3 can be more effectively suppressed.

[0088] An image-receiving layer may be formed by applying, for example, a polymer compound containing a pigment to the surface of the (E) image-recording paper substrate 20 (the surface opposite to the surface on which the (D) adhesive layer 18 is provided) to improve the receptivity of various inks, effectively suppress uneven transfer, and further improve the sharpness of the image. In addition, water-resistant agents such as epoxy compounds, fluorescent brighteners, antifoaming agents, antistatic agents, dyes, etc. may also be added to the surface of the (E) image-recording paper substrate 20 as needed.

[0089] The method for producing the adhesive sheet 3 is not particularly limited, but examples include applying a coating liquid containing an adhesive onto the surface of the (C) release agent layer 16 of the release paper 2 described above by a known method to form the (D) adhesive layer 18, and then laminating the (E) paper substrate 20 for image recording onto the (D) adhesive layer 18.

[0090] The release paper base paper 1 according to this embodiment can be suitably used as the release paper 2 of the adhesive sheet 3. The adhesive sheet 3 including the release paper base paper 1 according to this embodiment is compatible with a variety of printing methods, but the adhesive sheet 3 according to this embodiment can effectively prevent the adhesive sheet 3 from curling immediately after being discharged when printing with a laser beam printer, and is therefore more suitably used for printing with a laser beam printer.

[0091] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. [Example]

[0092] The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples. Note that percentages and the like are based on mass unless otherwise specified.

[0093] Example 1

[0094] (Preparation of release paper base paper 1)

[0095] Bleached softwood kraft pulp (NBKP) and bleached hardwood kraft pulp (LBKP) were mixed to a ratio of 16% by mass to 84% by mass, and the mixture was beaten in water by the Schopper-Rigler method to a beating degree of 46°SR. The mixture was dispersed in water to obtain a pulp slurry with a concentration of approximately 1% by mass. This pulp slurry was then made into paper using a fourdrinier multi-cylinder paper machine, and a basis weight of 55 g / m was obtained. 2 The paper base material 10 was obtained. The thickness of the paper base material 10 was 62 μm. The air permeability of the paper base material 10 was 50 seconds. The thickness of the paper base material 10 was measured in accordance with JIS P 8118:2014. The air permeability of the paper base material 10 was measured in accordance with JIS P 8117.

[0096] Next, a coating liquid containing 10% by mass of dextrin (manufactured by Sanwa Starch Co., Ltd., product name "Sandec #300") as component (b) in terms of solid content and water as a solvent was prepared. Next, the coating liquid was dried to a coating weight of 0.7 g / m 2 The coating liquid was applied by hand coating to one surface of the paper substrate 10 so that the coating liquid was in the range of 0.1 to 1.0, and then dried at 105°C for 2 minutes to form a coating layer 12 on the surface of the paper substrate 10. The dry adhesion amount of this coating liquid was the dry adhesion amount of component (b) in the coating layer 12. In this way, the release paper base paper 1 (coating layer 12 / paper substrate 10) shown in Figure 1 was obtained.

[0097] (Preparation of release paper 2)

[0098] A coating solution for a filling layer containing 50 parts by mass of clay and 50 parts by mass of polyvinyl alcohol was applied to the surface opposite to the surface containing the coating agent layer 12 of the base paper for release paper 1 obtained above in a dry deposition amount of 2.0 g / m 2 The coating was applied by hand coating so that the coating amount was 1.0 g / m2, and then dried at 105°C for 2 minutes to form the sealing layer 14. Subsequently, a silicone release agent was applied to the sealing layer 14 so that the dry adhesion amount was 1.0 g / m2. 2 and curing at 130°C for 30 seconds to form a release agent layer 16 (thickness: approximately 1 µm). In this way, the release paper 2 (coating agent layer 12 / paper substrate 10 / filler layer 14 / release agent layer 16) shown in Figure 2 was obtained.

[0099] (Preparation of adhesive sheet 3)

[0100] An emulsion-type adhesive composition was applied to the surface of the release agent layer 16 of the release paper 2 obtained above to form an adhesive layer 18 (coating amount 16 g / m 2 Then, a high-quality surface substrate (basis weight 53 g / m) was formed on the surface of the adhesive layer 18, which was a paper substrate 20 for image recording. 2, a thickness of 62 μm determined in accordance with JIS P 8118:2014, and an air permeability of 25 seconds determined in accordance with JIS P 8117) were bonded together to obtain the adhesive sheet 3 (coating agent layer 12 / paper substrate 10 / filler layer 14 / release agent layer 16 / adhesive layer 18 / image-recording paper substrate 20) shown in Figure 3. The difference in air permeability between the release paper base paper 1 and the image-recording paper substrate 20 was 70 seconds.

[0101] <Example 2>

[0102] Release paper base paper 1, release paper 2, and adhesive sheet 3 were obtained in the same manner as in Example 1, except that the dry adhesion amount of the coating liquid containing component (b) was changed to the amount shown in Table 1. The dry adhesion amount of the coating liquid was the dry adhesion amount of component (b) in the coating agent layer 12. The difference in air permeability between release paper base paper 1 and the air permeability of paper substrate 20 for image recording was 70 seconds.

[0103] Example 3

[0104] Release paper base paper 1, release paper 2, and adhesive sheet 3 were obtained in the same manner as in Example 1, except that component (b) in Example 1 was changed to a polyamine resin (manufactured by Taoka Chemical Co., Ltd., product name "Sumirez (registered trademark) Resin SPI-102A") and the dry adhesion amount of the coating liquid containing component (b) was changed to the amount shown in Table 1. The dry adhesion amount of the coating liquid was the dry adhesion amount of component (b) in coating agent layer 12. The difference in air permeability between release paper base paper 1 and the air permeability of paper substrate 20 for image recording was 68 seconds.

[0105] Example 4

[0106] The coating fluid of Example 1 was changed to a coating fluid containing 5% by solids of a polyamine resin (manufactured by Taoka Chemical Co., Ltd., product name "Sumirez (registered trademark) Resin SPI-102A") and 5% by solids of oxidized starch (manufactured by Oji Cornstarch Co., Ltd., product name "Ace Y") as component (b), and water as the solvent. Release paper base paper 1, release paper 2, and pressure-sensitive adhesive sheet 3 were obtained in the same manner as in Example 1, except that the dry adhesion weight of the coating fluid containing component (b) was changed to the amount shown in Table 1. The dry adhesion weight of the coating fluid was the dry adhesion weight of component (b) in coating agent layer 12. The difference in air permeability between release paper base paper 1 and (E) image-recording paper substrate 20 was 93 seconds.

[0107] <Example 5>

[0108] Release paper base paper 1, release paper 2, and adhesive sheet 3 were obtained in the same manner as in Example 1, except that component (b) in Example 1 was changed to phosphated starch (manufactured by Oji Cornstarch Co., Ltd., product name "HSS Coat 300") and the dry adhesion amount of the coating liquid containing component (b) was changed to the amount shown in Table 1. The dry adhesion amount of the coating liquid was the dry adhesion amount of component (b) in the coating agent layer 12. The difference in air permeability between release paper base paper 1 and the air permeability of paper substrate 20 for image recording was 150 seconds.

[0109] <Comparative Example 1>

[0110] A release paper base paper, a release paper, and an adhesive sheet were obtained in the same manner as in Example 1, except that oxidized starch (manufactured by Oji Cornstarch Co., Ltd., product name "Ace Y") was used as component (b) in Example 1, and the dry adhesion amount of the coating liquid containing component (b) was changed to the amount shown in Table 1. The dry adhesion amount of the coating liquid was the dry adhesion amount of component (b) in the coating agent layer 12.

[0111] <Comparative Example 2>

[0112] A release paper base paper, a release paper, and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1, except that an anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd., product name "Polymerset HP-710") was used instead of component (b) in Example 1, and the dry adhesion amount of the coating liquid containing the anionic acrylic resin was changed to the amount shown in Table 1. The dry adhesion amount of the coating liquid was the dry adhesion amount of the anionic acrylic resin in the coating agent layer.

[0113] <Comparative Example 3>

[0114] A release paper base paper, a release paper, and an adhesive sheet were obtained in the same manner as in Example 1, except that polyvinyl alcohol (manufactured by Kuraray Co., Ltd., product name "Kuraray Poval PVA-103") was used instead of component (b) in Example 1, and the dry adhesion amount of the coating solution containing polyvinyl alcohol was changed to the amount shown in Table 1. The dry adhesion amount of the coating solution was the dry adhesion amount of polyvinyl alcohol in the coating agent layer.

[0115] <Comparative Example 4>

[0116] A release paper base paper, a release paper, and an adhesive sheet were obtained in the same manner as in Example 1, except that a styrene-butadiene latex (manufactured by Nippon A&L Inc., product name "SN-309R") was used instead of component (b) in Example 1, and the dry adhesion amount of the coating liquid containing the styrene-butadiene latex was changed to the amount shown in Table 1. The dry adhesion amount of the coating liquid was the dry adhesion amount of the styrene-butadiene latex in the coating agent layer.

[0117] <Measurement> The following measurements were carried out for each of the above Examples and Comparative Examples. The measurement results are shown in Table 1.

[0118] (Air permeability)

[0119] The air permeability was measured in accordance with JIS P 8117 for the release paper base paper 1 before the release paper was produced.

[0120] (Flexibility)

[0121] The flexibility was measured using a bending resistance tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name "Gurley flexibility tester") in accordance with the Gurley method specified in JIS L 1096:2010, by measuring the flexibility of the release paper base paper (25 mm x 38 mm test piece) before the release paper was produced. At this time, the flexibility was measured in the direction perpendicular (CD) to the molding direction (MD) of the release paper base paper. The measured flexibility was the minimum value of the flexibility of the release paper base paper.

[0122] <Evaluation> The following evaluations were carried out for each of the above Examples and Comparative Examples. The evaluation results are shown in Table 1.

[0123] (Curling due to printing)

[0124] The obtained adhesive sheet was cut to 210 mm x 297 mm (A4 size) and printed over an entire area of ​​190 mm x 270 mm using a laser beam printer (manufactured by Ricoh Co., Ltd., product name "RICOH SP C841"). Immediately after the printed adhesive sheet was ejected from the printer, it was placed on a table with the printed side facing up, and the height of the curl at the four corners of the adhesive sheet relative to the surface of the table was measured to evaluate the curl. The evaluation criteria are as follows: ⊚: The maximum height of the curl at the four corners was 5 mm or less. ◯: The maximum height of the curl at the four corners was more than 5 mm and 10 mm or less. △: The maximum height of the curl at the four corners was more than 10 mm and 20 mm or less. ×: The maximum height of the curl at the four corners exceeded 20 mm. XX: The adhesive sheet was rolled into a cylindrical shape.

[0125] Table 1 shows the compositions and evaluation results of each example and comparative example.

[0126] [Table 1]

[0127] From the above, it was at least confirmed that this example can suppress curling of the pressure-sensitive adhesive sheet due to printing. [Explanation of symbols]

[0128] 1...Releasing paper base paper 2...Release paper 3...Adhesive sheet 10…Paper base material 12...Coating layer 14...Filling layer 16...Release agent layer 18...Adhesive layer 20...Paper substrate for image recording

Claims

1. A release paper base paper comprising (A) a paper substrate and (B) a coating agent layer in this order, the (B) coating layer contains at least one component (b) selected from the group consisting of dextrin, polyamine resin, and starch, The air permeability of the release paper base paper as determined in accordance with JIS P 8117 is 180 seconds or less. Base paper for release paper.

2. The starch is at least one selected from the group consisting of phosphated starch, acetylated oxidized tapioca starch, and oxidized starch. The release paper base paper according to claim 1.

3. The dry adhesion amount of the component (b) in the coating agent layer (B) is 0.1 to 1.0 g / m ２ That is, The release paper base paper according to claim 1 or 2.

4. The (A) paper substrate is The air permeability measured in accordance with JIS P 8117 is 10 to 150 seconds. The release paper base paper according to claim 1 or 2.

5. the minimum softness of the release paper base paper, measured using a Gurley softness tester in accordance with the Gurley method specified in JIS L 1096:2010, is within the range of 0.10 to 0.35 mN; The release paper base paper according to claim 1 or 2.

6. A release paper comprising the base paper for release paper according to claim 1 or 2 and (C) a release agent layer, The sheet comprises, in this order, the (C) release agent layer, the (A) paper substrate, and the (B) coating agent layer, Release paper.

7. A paper substrate comprising the release paper according to claim 6, (D) a pressure-sensitive adhesive layer, and (E) a paper substrate for image recording, The image recording medium includes, in this order: (E) a paper substrate for image recording; (D) an adhesive layer; (C) a release agent layer; (A) a paper substrate; and (B) a coating agent layer. Adhesive sheet.

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