Release sheet

Abstract

To provide a water-soluble release sheet.SOLUTION: The release sheet comprises a water-soluble base material and a release agent layer containing a release agent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a release sheet. [Background technology]

[0002] Paper that is easily dispersible in water is known. Patent Document 1 discloses water-dispersible paper with excellent printability. Patent Documents 2 and 3 disclose water-dispersible paper in which the performance of the substrate is not likely to deteriorate even when an adhesive layer is provided. Patent Document 4 also discloses water-dispersible paper that causes less clogging in filters. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-158938 [Patent Document 2] Japanese Patent Application Publication No. 2020-143399 [Patent Document 3] International Publication No. 2018 / 221016 [Patent Document 4] International Publication No. 2018 / 180011 Summary of the Invention [Problem to be solved by the invention]

[0004] Until now, release sheets used as adhesive layers or protective sheets for various objects have been incinerated after use, which has resulted in the hassle of collecting the release sheets for incineration at work sites.

[0005] An object of the present invention is to provide a release sheet that is water-soluble. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have found that by providing a water-soluble substrate and a release agent layer containing a release agent, it is possible to impart water solubility to the release sheet, thereby improving convenience while being environmentally friendly. In this way, the above-mentioned problems can be solved, and after further research, they have completed the present invention.

[0007] That is, the present invention relates to the following [1] to [8]. [1] A water-soluble substrate and a release agent layer containing a release agent, A release sheet characterized by: [2] A sealing layer containing a water-soluble sealing material is further provided between the substrate and the release agent layer. The release sheet according to [1], [3] The filling layer is A layer containing polyvinyl alcohol (PVA), The release sheet according to [2], [4] The degree of saponification of the polyvinyl alcohol is 97.0 mol% or less. The release sheet according to [3], [5] The coating amount of the sealing material is 0.5 g / m 2 More than 50.0g / m 2 Below is the The release sheet according to any one of [2] to [4] above. [6] The release agent is a silicone-based release agent. The release sheet according to any one of [1] to [5] above. [7] The coating amount of the release agent is 0.1 g / m 2 More than 3.0g / m 2 Below is the The release sheet according to any one of [1] to [6] above. [8] The smoothness of the surface of the substrate according to JIS P 8119 is 1 second or more and 1000 seconds or less; The release sheet according to any one of [1] to [7] above. [Effects of the Invention]

[0008] A release sheet may be provided that is water soluble. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view of a release sheet according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. Furthermore, the same reference numerals are used to designate identical or similar components, and redundant descriptions will be omitted.

[0011] (definition) In this specification, the term "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid", and the same applies to other similar terms.

[0012] In this specification, when one or more lower limits and one or more upper limits of a numerical range (e.g., a range of content, etc.) are described, it can be understood that any combination of the lower limit and upper limit therein is described. For example, a description such as "preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and preferably 9 or less, more preferably 8 or less, even more preferably 7 or less" clearly means that the numerical range may be any of 1 or more to 9 or less, 1 or more to 8 or less, 1 or more to 7 or less, 2 or more to 9 or less, 2 or more to 8 or less, 2 or more to 7 or less, 3 or more to 9 or less, 3 or more to 8 or less, and 3 or more to 7 or less.

[0013] In this specification, the term "water-soluble" refers to the property of dissolving or dispersing in water, or of easily disintegrating upon contact with water, and broadly includes concepts such as water solubility, water solubility, water dispersibility, and water disintegrability.

[0014] (Release sheet) A release sheet according to one embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a schematic diagram of a release sheet 1 according to one embodiment. The release sheet 1 comprises a water-soluble substrate 10 and a release agent layer 11. This makes it possible to impart water solubility to the release sheet, thereby improving convenience while being environmentally friendly. The release sheet 1 may also comprise a filling layer 12 between the substrate 10 and the release agent layer 11, which contains a water-soluble filling material.

[0015] (base material) The substrate 10 functions, for example, as a support for the release agent layer 11. The substrate 10 also functions, for example, as a protective layer depending on the application of the release sheet 1. The type of substrate 10 is not particularly limited as long as it is water-soluble, and it can be a hard substrate or a flexible substrate. The substrate 10 may also be a flexible substrate from the viewpoints of improving releasability, facilitating lamination, or enabling it to be formed into a roll form. Specifically, for example, a paper substrate, a water-soluble film, or the like can be used as the substrate 10.

[0016] The paper substrate is preferably water-soluble paper or water-decomposable paper, for example, to enhance water solubility. Water-soluble paper is paper in which the constituent fibers disperse and dissolve in water. There are no particular limitations on such water-soluble paper, and water-soluble papers such as fibrous CMC (carboxymethyl cellulose) salt paper-making type, fibrous CMC acid paper-making type, and laminate carboxymethylated type can be used. Here, the fibrous CMC salt paper-making type is water-soluble paper obtained by papermaking a water-soluble fibrous CMC salt, and wood pulp is usually blended during papermaking to improve papermaking properties. In addition, the fibrous CMC acid paper-making type is water-soluble paper obtained by papermaking a sheet from water-insoluble fibrous CMC acid (free CMC) and then treating it with an alkaline solution to form a water-soluble fibrous CMC salt, and wood pulp can also be blended in some cases. Furthermore, the carboxymethylated laminate is a water-soluble paper obtained by first forming a sheet-like cellulose-based laminate and then carboxymethylating it as is, and paper, rayon nonwoven fabric, etc. can be used as the cellulose-based laminate.

[0017] Water-dispersion paper is paper that contains almost no water-soluble fibers and disintegrates in water, ultimately dispersing into individual fibers. This water-dispersion paper can be made from wood pulp, wood pulp and binder combinations, or wet-laid nonwoven fabrics. Wood pulp types are water-dispersion paper made by not beating wood pulp fibers much to minimize the loss of their inherent water dispersibility, resulting in low-basis weight sheets. Wood pulp and binder combinations are water-dispersion paper made from the wood pulp type by adding special binders, such as alkaline earth metal salts of CMC, carrageenan, and dialdehyde starch, that improve wet strength against water-alcohol-based detergents. Wet-laid nonwoven fabrics are water-dispersion paper made by fixing and laminating rayon or polyester fibers, which have weak interfiber bonding strength, with water-soluble polyvinyl alcohol binder fibers.

[0018] The basis weight of the paper substrate is, for example, 10 g / m from the viewpoint of increasing the water solubility of the release sheet. 2 It is preferable that the content is 15 g / m or more, and more preferably 15 g / m 2More preferably, it is 20 g / m or more. 2 or more, 250 g / m 2 It is preferable that the weight is 200 g / m or less, and more preferably 200 g / m 2 More preferably, it is 150 g / m or less. 2 The following is the result.

[0019] The water-soluble film is a film that uses a water-soluble polymer material as its main material, and may be made of the water-soluble polymer material alone or may contain additives in addition to the water-soluble polymer material. Specific examples of water-soluble polymers that make up the water-soluble film include polyvinyl alcohol-based resins such as polyvinyl alcohol, saponified copolymers of unsaturated carboxylic acids such as acrylic acid, maleic acid, fumaric acid, itaconic acid, and allyl acetate with vinyl acetate, and esters with acid anhydrides such as succinic anhydride, phthalic anhydride, and maleic anhydride; polyacrylamide; sodium polyacrylate; polyvinylpyrrolidone; cellulose-based resins such as acetyl cellulose, acetylbutyl cellulose, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose; and various water-soluble polymers such as starch, dextrin, gelatin, glue, and sodium alginate. These water-soluble polymers may be used alone or in combination.

[0020] The substrate 10 may also be a laminated film in which two or more types of water-soluble films are laminated together, or may be a substrate in which a paper substrate and a water-soluble film are laminated together.

[0021] Furthermore, the smoothness of the surface of the substrate 10 on the release agent layer 11 side, measured in accordance with JIS P 8119, is preferably 1 second or more from the viewpoint of improving releasability. The upper limit of this smoothness is preferably 1000 seconds or less, more preferably 300 seconds or less, and even more preferably 200 seconds or less. The smoothness of the surface of the substrate 10 on the release agent layer 11 side can be appropriately selected depending on, for example, the amount of release agent applied.

[0022] In addition, for example, from the viewpoint of increasing the smoothness, the surface of the substrate 10 on the release agent layer 11 side may be treated using a treatment device such as a machine calender, a super calender, a gloss calender, or a soft calender.

[0023] The thickness of the substrate 10 is not particularly limited, but is preferably 10 μm or more and 350 μm or less from the viewpoint of achieving both supportability and roll winding properties. The lower limit of the thickness of the substrate 10 is more preferably 20 μm or more, and even more preferably 30 μm or more. The upper limit of the thickness of the substrate 10 is more preferably 300 μm or less, and even more preferably 250 μm or less.

[0024] (Release agent layer) The release agent contained in the release agent layer 11 is not particularly limited, and examples thereof include silicone-based resins, fluorine-based resins, alkyd resins, long-chain alkyl-based resins, olefin-based resins, various waxes, etc. Among these, from the viewpoint of excellent releasability, the release agent is preferably a silicone-based resin.

[0025] 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.

[0026] The silicone resin can be used in any of the solvent-based, solventless, and emulsion forms, but emulsion and solventless forms are preferred. From an environmental consideration perspective, emulsion silicone resins are more preferred. By using an emulsion silicone resin as the release agent, it is possible to suppress the generation of VOCs (Volatile Organic Compounds) during the production of the release sheet 1.

[0027] The coating amount of the release agent is 0.1 g / m2 in dry weight. 2 More than 3.0g / m2 The lower limit of the coating amount is preferably 0.2 g / m or less. 2 More preferably, it is 0.5 g / m or more. 2 The upper limit of the coating amount is 2.5 g / m or more. 2 More preferably, it is 2.0 g / m or less. 2 It is even more preferable that the coating amount of the release agent is less than or equal to 100%. By controlling the coating amount of the release agent within this range, the release sheet 1 can be made water-soluble and have a more appropriate and stable release force. However, the coating amount of the release agent that allows the release sheet 1 to be water-soluble can be selected appropriately depending on the type of release agent, etc.

[0028] (Filling layer) The filling layer 12 serves to prevent the release agent composition contained in the release agent layer 11 from penetrating into the substrate 10, as well as to improve adhesion between the substrate 10 and the release agent layer 11 and to obtain smoothness of the surface of the release agent layer 11. By providing the filling layer 12, it is possible to prevent a decrease in the water solubility of the release sheet 1 due to penetration of the release agent composition into the substrate 10.

[0029] The filling layer 12 includes, for example, a filling material. Examples of the filling material 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; methyl methacrylate-butadiene copolymers, (meth)acrylic acid, and copolymerizable monomer components (excluding olefins) with (meth)acrylic acid. acrylic resins; 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; styrene resins such as styrene-maleic anhydride copolymer, styrene-butadiene copolymer, and styrene-acrylic copolymer; casein, gum arabic, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic acid ester, polyvinyl butyral, polystyrose and copolymers thereof, polyamide resins, silicone resins, petroleum resins, terpene resins, ketone resins, coumarone resins, dextrin, ethylene-vinyl chloride copolymer, and ethylene-vinyl acetate copolymer.

[0030] Among these, the sealing material is preferably a water-soluble polymer material from the viewpoint of water solubility. Specifically, a polyvinyl alcohol (PVA) resin is preferred, more preferably a fully saponified polyvinyl alcohol or a partially saponified polyvinyl alcohol, and even more preferably a partially saponified polyvinyl alcohol.

[0031] The viscosity at 20°C of the polyvinyl alcohol (PVA) resin contained in the sealing layer 12 is preferably 3.0 mPa·s or more, more preferably 20 mPa·s or more, even more preferably 40 mPa·s or more, and is preferably 130 mPa·s or less, more preferably 125 mPa·s or less, and even more preferably 120 mPa·s or less. By controlling the viscosity of the polyvinyl alcohol resin within this range, it is possible to prevent the sealing material from penetrating into the substrate and to prevent a decrease in the water solubility of the release sheet 1.

[0032] Furthermore, from the viewpoint of increasing the water solubility of the release sheet 1, the degree of saponification of the polyvinyl alcohol (PVA) resin contained in the sealing layer 12 is preferably 70 mol% or more, more preferably 75 mol% or more, even more preferably 80 mol% or more, even more preferably 85 mol% or more, and is preferably 97 mol% or less, more preferably 95 mol% or less, even more preferably 93 mol% or less, even more preferably 90 mol% or less.

[0033] Furthermore, the filling layer 12 may contain, for example, an inorganic pigment in addition to the filling material. Examples of the inorganic pigment include light calcium carbonate, heavy calcium carbonate, kaolin, calcined kaolin, engineered kaolin, clay, delaminated clay, talc, silica, colloidal silica, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, calcium silicate, magnesium silicate, aluminum hydroxide, alumina, magnesium carbonate, magnesium hydroxide, kaolinite, antigorite, smectite, vermiculite, and mica.

[0034] Furthermore, the sealing layer 12 may contain, as necessary, various commonly used auxiliaries such as a sizing agent, a water-resistant agent, a water-repellent agent, a dye, a surfactant, a dispersant, a thickener, a water-retaining agent, an antifoaming agent, a water-resistant agent, a dye, a fluorescent dye, and a crosslinking agent.

[0035] The coating amount of the sealing layer 12 is 0.5 g / m2 in terms of dry weight. 2 More than 50.0g / m 2 The lower limit of the coating amount is preferably 0.7 g / m or less. 2 It is preferably 1.0 g / m or more. 2 The upper limit of the coating amount is 10.0 g / m or more. 2 More preferably, it is 5.0 g / m or less. 2 By controlling the coating amount of the filling layer 12 within such a range, the release sheet 1 can be made water-soluble, and the release agent of the release agent layer 11 or the filling material of the filling layer 12 can be prevented from penetrating into the substrate 10.

[0036] The filling layer 12 may be one layer (single layer) or two or more layers. When the filling layer 12 is a plurality of layers, these layers may be the same or different from each other, and the combination of these layers is not particularly limited.

[0037] The release strength of the release sheet 1 can be appropriately adjusted depending on the application of the release sheet 1, but from the viewpoint of maintaining a practical level of release strength, it is preferably, for example, 10 mN / 25 mm or more and 2000 mN / 25 mm or less. The upper limit is more preferably 1500 mN / 25 mm or less, and even more preferably 1000 mN / 25 mm or less. The lower limit is more preferably 20 mN / 25 mm or more, and even more preferably 25 mN / 25 mm or more.

[0038] (Other layers) The pressure-sensitive adhesive sheet 1 described above may have layers other than the substrate 10, the release agent layer 11, and the filling layer 12. For example, an additional release agent layer and filling layer may be provided on the surface of the substrate 10 opposite to the release agent layer 11 and the filling layer 12.

[0039] (Production method of release sheet) There are no particular limitations on the method for producing the release sheet 1. For example, the release sheet 1 can be produced as follows. First, an organic solvent is added to a raw material composition containing the components of the filling layer 12 described above to prepare a solution of the raw material composition. This solution is then applied to the substrate 10 to form a coating film, which is then dried, thereby providing the filling layer 12 on the substrate 10. Next, raw material compositions containing the components of the release agent layer 11 described above are mixed to prepare a solution of the raw material composition. This solution is then applied to the filling layer 12 to form a coating film, which is then dried, thereby providing the filling layer 12 and the release agent layer 11 on the substrate 10.

[0040] Examples of organic solvents used to prepare the solution of the raw material composition include toluene, ethyl acetate, and methyl ethyl ketone. Examples of methods for applying the solution include spin coating, spray coating, bar coating, knife coating, roll coating, roll knife coating, blade coating, die coating, gravure coating, and printing methods (e.g., screen printing and inkjet printing).

[0041] The method for drying the solution is not particularly limited, and for example, a common method such as a steam heater, a gas heater, an infrared heater, an electric heater, a hot air heater, a microwave, or a cylinder dryer can be used.

[0042] (Use of release sheet) One embodiment of the release sheet of the present invention may be a laminate comprising a pressure-sensitive adhesive sheet having a substrate and a pressure-sensitive adhesive layer, and a release sheet. The release sheet may be used, for example, as a protective sheet to protect pressure-sensitive adhesive sheets for hygiene products such as diapers, cleaning tools, deodorants, air fresheners, etc. The release sheet may also be used as a protective sheet to protect pressure-sensitive adhesive sheets for building materials. The release sheet may also be used for protecting pressure-sensitive adhesive sheets attached to semiconductor products such as hard disk drives, relays, switches, other precision electronic devices, and precision electronic components, or for protecting pressure-sensitive adhesive sheets for sealing medical supplies and food, etc., or display labels, etc. The release sheet is water-soluble, and therefore can be flushed down toilets, sinks, kitchens, etc. after use in the above-mentioned applications.

[0043] <Example> The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. In each example, parts and percentages are by weight unless otherwise specified.

[0044] In the examples, the following release agents, fillers, and substrates were used.

[0045] <Removal agent (A)> The main component (A1) and catalyst (A2) below were mixed in a mass ratio of 90:10 to prepare a release agent.

[0046] <Main agent (A1)> Emulsion silicone: (manufactured by Dow Toray Industries, Inc., product name "7920NF Emulsion Coating").

[0047] <Catalyst (A2)> Catalyst (Dow Toray Industries, Inc., product name "7924 Catalyst Emulsion") <Sealing agent (B)> The following sealing material (B1) and solvent (B2) were mixed in a mass ratio of 95.5:4.5 to prepare a sealing agent.

[0048] <Sealing material (B1)> Polyvinyl alcohol (manufactured by Kuraray Co., Ltd., product name "Kuraray Poval (95-88)", volatile content: 5.0% or less, sodium acetate: 1.0% or less, saponification degree: 97.0-89.0 mol%, viscosity at 20°C: 80.0-110.0, purity: 94.0% or more) <Solvent (B2)> ·water <Base material (C)> Water-soluble paper (manufactured by Nippon Paper Papylia Co., Ltd., product name "60MDP, 60CD-2", thickness: 110μm (60MDP), 95μm (60CD-2), basis weight: 60g / m2 (60MDP, 60CD-2).

[0049] The release sheet produced using the above-mentioned release agent (A), filler (B), and substrate (C) will be described in detail below.

[0050] Example 1 The filler (B) was applied to the substrate (C) and dried at 150°C for 1 minute to obtain a coating of 1.2 g / m 2 A release agent (A) was applied onto the filling layer and dried at a temperature of 150°C for 1 minute to form a filling layer of 1.2 g / m 2 A release agent layer of the above formula was formed to prepare a release sheet.

[0051] Examples 2 to 9 A release sheet was prepared in the same manner as in Example 1, except that the coating amounts of the release agent (A) and the filler (B) were as shown in Table 1.

[0052] (Examples 10 to 15) A release sheet was produced in the same manner as in Example 1, except that the coating amounts of the release agent (A) and the filler (B) were as shown in Table 1 and the substrate (C) was subjected to a calendar treatment to achieve smoothness as shown in Table 1.

[0053] [Table 1]

[0054] <Measurement and evaluation methods> (Measurement of the smoothness of the substrate) The Bekk smoothness of the surface of the substrate on which the sealing layer and release agent layer were laminated was measured in accordance with JIS P 8119 (1998) for each of the release sheets of Examples 10 to 15. For each of the release sheets of Examples 1 to 9, no calendering treatment was performed, and therefore no smoothness was measured.

[0055] (Evaluation of water solubility of release sheets) The water solubility of the release sheets prepared in Examples 1 to 3 and Examples 7 to 9 was evaluated. Specifically, for the evaluation of water solubility, the release sheets prepared in Examples 1 to 3 and Examples 7 to 9 were each cut into a 5 cm x 5 cm square to prepare test specimens. A glass bottle containing 100 g of water was prepared for each test specimen of each Example. The test specimen was then placed in the glass bottle and shaken up and down 50 times, after which the state of the release sheet was observed to evaluate the water solubility of the test specimen. Table 2 shows the evaluation results of water solubility. In Table 2, ◯ indicates that the test specimen was well dissolved in water, and × indicates that the test specimen was less water soluble.

[0056] [Table 2]

[0057] It was confirmed that the release sheet tended to be more soluble in water, regardless of the amount of sealant applied, by reducing the amount of release agent applied as in Examples 1 to 3. This is thought to be because reducing the amount of release agent applied reduced the amount of release agent that penetrated into the substrate, making the release sheet more soluble in water.

[0058] (Evaluation of water decomposability of release sheet) The water-disintegrability of the release sheets prepared in Examples 1, 4, and 7 was evaluated using a disintegration test in accordance with JIS P 4501:1993 "Toilet Paper." Specifically, the release sheets prepared in Examples 1, 4, and 7 were each cut into 114 mm squares to prepare test pieces. A 300 ml beaker containing 300 ml of water and a rotor was placed on a magnetic stirrer, and the rotor was adjusted to rotate at 600 rpm. The test piece was then placed in the rotating beaker, and time measurement was initiated. After the rotor's rotation speed decreased to approximately 500 rpm due to the resistance of the test piece, the time until the rotor recovered to 540 rpm as the test piece disintegrated was measured and evaluated. Table 3 shows the results of the water-disintegrability evaluation. In Table 3, ◯ indicates a measured value within 100 seconds, and × indicates a value exceeding 100 seconds.

[0059] [Table 3]

[0060] It was confirmed that the release sheet tends to become more easily unraveled in water when the coating amount of the release agent is reduced, as in Examples 1 and 4. This is thought to be because reducing the coating amount of the release agent reduces the amount of release agent that penetrates into the substrate, making the release sheet more easily unraveled in water.

[0061] (Evaluation of the release force of the release sheet) An acrylic adhesive (manufactured by Toyochem Co., Ltd., product name "Olivine (registered trademark) BPW-6401") was applied using an applicator onto the release agent layer of the release sheet prepared in each Example, and dried at 110°C for 2 minutes to form an adhesive layer with a thickness of 100 μm. Furthermore, a piece of wood-free paper (manufactured by Nippon Paper Industries Co., Ltd., product name "WM Seal 64 printed surface outer wrap", thickness 73 μm) was attached to the surface of the adhesive layer opposite the release sheet to obtain a measurement sample.

[0062] The test sample was fixed to a universal tensile tester (manufactured by A&D Co., Ltd., product name "Tensilon Universal Tester RTI-1225"), and the force when peeled from the fine paper in a 180° direction at a pulling rate of 0.3 m / min was measured in accordance with JIS Z0237:2009, and this was taken as the peel force (mN / 50 mm). Table 4 shows the evaluation results of the peel force.

[0063] [Table 4]

[0064] As in Examples 1 to 15, the release force required to peel the release sheet tends to decrease when the coating amount of the release agent is large. Furthermore, as in Examples 10 to 15, increasing the smoothness of the substrate further reduces the release force of the release sheet. This is thought to be because increasing the smoothness of the substrate makes it easier for the release agent to be uniformly coated on the substrate. Thus, by appropriately adjusting the smoothness of the substrate, a release force appropriate for the application of the release sheet can be obtained.

[0065] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention. [Explanation of symbols]

[0066] 1 release sheet, 10 substrate, 11 release agent layer, 12 sealing layer

Claims

1. The ink-jet recording medium comprises a water-soluble substrate and a release agent layer containing a release agent. A release sheet characterized by:

2. a sealing layer containing a water-soluble sealing material between the substrate and the release agent layer, The release sheet according to claim 1 .

3. The filling layer is A layer containing polyvinyl alcohol (PVA), The release sheet according to claim 2 .

4. The degree of saponification of the polyvinyl alcohol is 97.0 mol% or less. The release sheet according to claim 3 .

5. The coating amount of the sealing material is 0.5 g / m ２ 50.0g / m or more ２ Below is the The release sheet according to claim 2 .

6. The release agent is a silicone-based release agent. The release sheet according to claim 1 .

7. The coating amount of the release agent is 0.1 g / m ２ 3.0g / m or more ２ Below is the The release sheet according to claim 1 .

8. The smoothness of the surface of the substrate according to JIS P 8119 is 1 second or more and 1000 seconds or less. The release sheet according to claim 1 .

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