Release paper and adhesive sheet

Abstract

The utility model provides release paper and an adhesive sheet, in the release paper, a paper base material, a barrier layer and a release agent layer are laminated in sequence, and a concave-convex structure is formed on the exposed surface of the release agent layer. In the release paper disclosed by the utility model, the release layer is directly formed on the barrier layer, and plastic films such as polyethylene are not laminated. Therefore, the environment-friendly embossed release paper in which polyethylene is not laminated and the adhesive sheet having the release paper can be obtained.

Description

Technical Field

[0001] The utility model relates to a release paper and an adhesive sheet. Background Art

[0002] PSA sheets with release paper, in which a release paper is laminated on a substrate sheet via an adhesive layer, are used for decoration, display, and other applications. When the PSA sheet is large in area, air can easily accumulate between the adhesive layer and the adherend during application, detracting from the sheet's aesthetics. To address this issue, a technology is known (see Patent Document 1) that provides concave and convex portions on the surface of the release paper, thereby allowing air (gas) to flow between the adhesive layer and the adherend.

[0003] In the PSA sheet disclosed in Patent Document 1, a so-called polyethylene-laminated release paper is often used as the release liner. Specifically, a plastic film, such as polyethylene, is laminated onto a paper substrate, with a release agent layer formed thereon. In recent years, the problem of plastic waste has become increasingly serious, and as an environmental measure, plastic removal has become increasingly important, leading to demands for reduced plastic usage.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 07-224254 Utility Model Content

[0006] The present invention is proposed in view of the above problems, and its object is to provide a release paper having concave-convex portions on its surface without using a plastic film, and an adhesive sheet having the release paper.

[0007] In order to achieve the above-mentioned object, the present invention provides a release paper, wherein a paper substrate, a barrier layer and a release agent layer are stacked in sequence, and a concave-convex structure is formed on the exposed surface of the release agent layer.

[0008] In the above-mentioned release paper, the concavo-convex structure is formed on the surface of the barrier layer in contact with the release agent layer.

[0009] In the above-mentioned release paper, the concavo-convex structure is formed on the exposed surface of the paper substrate.

[0010] In the above-mentioned release paper, in the concavo-convex structure, the interval between two adjacent concave portions is greater than or equal to 0.5 mm and less than or equal to 5 mm.

[0011] In the above-mentioned release paper, the release agent in the release agent layer is a silicone resin.

[0012] In the above release paper, the basis weight of the paper substrate is 30g / m 2 ~300g / m 2 .

[0013] In the above-mentioned release paper, the thickness of the release agent layer is 0.01 μm to 10 μm.

[0014] In the above release paper, the barrier layer contains inorganic pigments.

[0015] In addition, the present invention also provides an adhesive sheet, wherein a substrate layer, an adhesive layer and the above-mentioned release paper are stacked in sequence.

[0016] In the above-mentioned pressure-sensitive adhesive sheet, the concavo-convex structure of the release agent layer is transferred to the surface of the pressure-sensitive adhesive layer.

[0017] In the release paper of the present invention, the release layer is formed directly on the barrier layer without laminating a plastic film such as polyethylene. Therefore, the release paper of the present invention can provide an environmentally friendly embossed release paper without polyethylene lamination, as well as an adhesive sheet having the release paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic cross-sectional view of a release paper according to one embodiment of the present invention.

[0019] Figure 2 It is a cross-sectional schematic diagram of a release paper according to another embodiment of the present invention.

[0020] Figure 3 It is a cross-sectional schematic diagram of a release paper according to another embodiment of the present invention.

[0021] Figure 4 Schematic diagram of embossing release paper using an off-line embossing process.

[0022] Figure 5 This is a pressure-sensitive adhesive sheet according to one embodiment of the present invention.

[0023] Figure 6 Comparison photos of synthetic leather sheets made using release papers produced using two different embossing methods.

[0024] Description of Reference Numerals

[0025] 10: Paper substrate,

[0026] 20: Barrier layer,

[0027] 30: Release agent layer,

[0028] 40: base material layer,

[0029] 50: adhesive layer,

[0030] 100: embossing roller,

[0031] 200: Wool roller. DETAILED DESCRIPTION

[0032] The following describes embodiments of the present invention with reference to the accompanying drawings. However, the release paper and adhesive sheet disclosed in the following embodiments are merely examples, and are not limited to the following embodiments as long as the effects of the present invention can be achieved.

[0033] Figure 1 Schematic cross-sectional view of a release paper according to an embodiment of the present invention. Figure 1 As shown, the release paper is formed by sequentially laminating a paper base material 10 , a barrier layer 20 and a release agent layer 30 , and a concavo-convex structure is formed on the exposed surface of the release agent layer 30 .

[0034] Examples of the paper substrate 10 include natural pulp paper having coniferous pulp, broadleaf pulp, and mixed coniferous and broadleaf pulp as a main component. The thickness of the paper substrate is not particularly limited, but is preferably smooth, and its basis weight is preferably 30 to 300 g / m 2 For example, the basis weight of a paper substrate may be 30 g / m 2 , 40g / m 2 , 50g / m 2 , 100g / m 2 , 120g / m 2 , 150g / m 2 , 200g / m 2 , 230g / m 2 , 250g / m 2 , 270g / m 2 , 300g / m 2 , or a range consisting of any two of the above values.

[0035] The paper substrate may contain various polymer compounds and additives. For example, the following substances may be appropriately combined and contained: dry paper strengthening agents such as starch, starch derivatives (cationized starch, phosphated starch, oxidized starch, etc.), polyacrylamide, polyvinyl alcohol, polyvinyl alcohol derivatives (completely saponified, partially saponified, carboxyl-modified, cationically modified, and various other modified polyvinyl alcohols), gelatin (alkali-treated, acid-treated, and various modified gelatins), natural polymer polysaccharides such as rosin or alginic acid derivatives, higher fatty acid metal salts, rosin derivatives, dialkyl ketones, alkenyl or alkenyl succinic anhydrides, and epoxidized higher fatty acid amides. Additives include sizing agents such as organic fluorine compounds and dialkyl ketene dimer emulsions, wet paper strength enhancers such as polyamide-polyamine epichlorohydrin resins, melamine resins, urea resins, and epoxidized polyamide resins, stabilizers, pigments, dyes, antioxidants, fluorescent brighteners, various latexes, inorganic electrolytes (sodium chloride, sodium sulfate, sodium phosphate, calcium chloride, lithium chloride, magnesium chloride, magnesium sulfate, barium chloride, etc.), pH adjusters, fixatives such as aluminum sulfate or aluminum chloride, fillers such as calcium carbonate, kaolin, talc, and clay, and organic conductive agents. These ingredients can be dispersed in the pulp slurry during the papermaking stage, added to a tab sizer after papermaking, or applied as a solution using various coating machines.

[0036] The barrier layer 20 is used to prevent the release agent from penetrating the paper substrate. Examples of resins contained in the barrier layer include copolymers such as styrene-butadiene copolymers, ethylene-vinyl chloride copolymers, methyl methacrylate-butadiene copolymers, ethylene-vinyl acetate copolymers, and (meth)acrylate copolymers; and water-soluble resins such as casein, dextrin, starch, oxidized starch, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and polyvinyl alcohol. These resins can be used alone or in combination of two or more.

[0037] The barrier layer 20 preferably contains an inorganic pigment, and more preferably contains the aforementioned resin and an inorganic pigment. Examples of inorganic pigments include light calcium carbonate, heavy calcium carbonate, kaolin, calcined kaolin, engineered-grade 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, aluminum oxide, magnesium carbonate, magnesium hydroxide, kaolinite, antigorite, montmorillonite, and vermiculite mica. Of these, at least one selected from kaolin, calcined kaolin, and engineered-grade kaolin is preferred, with kaolin being more preferred. These inorganic pigments may be used alone or in combination of two or more.

[0038] The content of the inorganic pigment is not particularly limited, but from the viewpoint of smoothness and adhesion, it is preferably 1 to 1400 parts by mass, more preferably 200 to 600 parts by mass, further preferably 250 to 500 parts by mass, and even more preferably 300 to 400 parts by mass relative to 125 parts by mass of the dry weight of the binder resin.

[0039] If necessary, the barrier layer may contain various commonly used auxiliary agents such as a sizing agent, a water-resisting agent, a water-proofing agent, a dye, a surfactant, a dispersant, a thickener, a water-retaining agent, a defoaming agent, a fluorescent dye, and a cross-linking agent.

[0040] The barrier layer preferably does not contain polyolefins. If the barrier layer is a polyolefin-free barrier layer, the above-mentioned requirements for "plastic removal" and recyclability can also be fully met.

[0041] The method for forming the barrier layer on the surface of the paper substrate is not particularly limited. Examples of conventionally known methods include: a method of applying a coating liquid containing a biodegradable resin and a biomass-derived resin onto the paper substrate and drying the coating liquid to form the barrier layer; a method of laminating the paper substrate and the barrier layer with an adhesive; and a method of simultaneously extruding the paper substrate and the barrier layer using a melt extrusion method.

[0042] The release agent contained in the release agent layer 30 is not particularly limited, and examples thereof include silicone resins, fluorine resins, alkyd resins, long-chain alkyl resins, various waxes, and the like. Among them, silicone resins are preferred because of their excellent releasability.

[0043] The silicone resin may be used in any of solvent-based, solvent-free, and emulsion-based forms, but the emulsion-based and solvent-free forms are preferred.

[0044] The thickness of the release agent layer 30 is preferably 0.01 to 10 μm. For example, 0.01 μm, 0.05 μm, 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. A range consisting of any two of these values ​​is also possible. The lower limit of the thickness is more preferably 0.1 μm or greater. The upper limit of the thickness is more preferably 5 μm or less.

[0045] The release agent layer 30 can be formed by applying a coating liquid containing the release agent onto a portion of the surface of the barrier layer 20 of the paper substrate 10, heating it, and curing it. The coating method is not particularly limited, and for example, a method using a variety of coating devices such as a blade coater, an airknife coater, a rod blade coater, a barblade coater, a gravure coater, a bar coater, or a multi-stage roll coater can be used.

[0046] As a method of forming a concavo-convex structure on the surface of the release agent layer 30 , embossing is generally used.

[0047] Embossing is not particularly limited. For example, it is preferred to form a concave-convex structure on the release layer 30 through post-processing such as offline embossing. Offline embossing is a method of using an embossing roller to press the flat surface of laminated or coated paper. The following embossing methods can be used: matched steel embossing, steel-on-steel embossing (double steel roller embossing), paper-on-steel embossing, rubber-on-steel embossing, rubber-on-wool embossing, flat steel embossing, high-pressure embossing, and heat embossing.

[0048] In the concave-convex structure, the spacing between two adjacent concave portions is at least 0.5 mm and less than 5 mm. If the spacing between the concave portions is within this range, the undesirable situation of reduced adhesion due to a small bonding area (the area of ​​the adhesive in contact with the adherend) is less likely to occur. If wool embossing is used, the spacing between two adjacent concave portions is at least 0.5 mm and less than 5 mm. Compared to conventional steel-on-steel embossing, the use of a highly elastic wool roller allows for deeper patterns to be applied. Figure 4 A schematic diagram of embossing release paper using an offline embossing process is shown, wherein the upper roller is, for example, a steel roller, a rubber roller, etc., and the lower roller is a wool roller.

[0049] Figure 2 This is a schematic cross-sectional view of another embodiment of a release paper according to the present invention. In this release paper, in addition to the concavo-convex structure formed on the surface of the release agent layer 30, a concavo-convex structure is also formed on the surface of the barrier layer 20 that contacts the release agent layer 30. For example, a method for manufacturing this release paper can include embossing the barrier layer surface of a paper substrate having a barrier layer (e.g., in-line embossing) to form the concavo-convex structure, and then treating the barrier layer surface with a release agent. This results in a release paper having the concavo-convex structure formed on both the barrier layer 20 and the release agent layer 30.

[0050] Figure 3 This is a schematic cross-sectional view of another embodiment of a release paper according to the present invention. In this release paper, in addition to the concavo-convex structure formed on the surface of the release agent layer 30, the concavo-convex structure is also formed on the exposed surface of the paper substrate 10. This release paper can be manufactured, for example, by forming a release paper having a flat surface and then embossing the release agent layer surface and the paper substrate surface using heat pressing or the like (e.g., off-line embossing) to form the concavo-convex structure.

[0051] Figure 5 This is an adhesive sheet according to one embodiment of the present invention, comprising a substrate layer 40, an adhesive layer 50, and the release paper of the aforementioned embodiment stacked in sequence. The adhesive sheet is manufactured by applying an adhesive to the surface of the release agent layer of the release paper by a known method such as gravure coating, rod coating, spray coating, spin coating, roller coating, die coating, blade coating, air knife coating, or curtain coating, drying to form an adhesive layer, and then attaching the adhesive sheet substrate to the adhesive layer. Preferably, the concave-convex structure of the release agent layer 30 is transferred to the surface of the adhesive layer 50.

[0052] The substrate layer 40 of the present embodiment is not particularly limited and can be made of paper raw materials or a resin film with resin raw materials as the main component. From the viewpoint of reducing the environmental load, preferably paper, a recycled resin film made of recycled resin or a biomass resin film made of a resin derived from biomass, more preferably paper or a biomass resin film. As a paper-based adhesive sheet substrate, for example, coated paper such as high-quality paper, art paper, and coated paper, aluminum foil, colored paper, impregnated paper, glass paper, dust-free paper, etc. can be listed. As the resin used in the resin film, for example, polyester, polyethylene terephthalate, polyethylene, polylactic acid, polyurethane urea, vinyl chloride, polystyrene, polytetrafluoroethylene, polyimide, ABS (acrylonitrile-butadiene-styrene copolymer), polyester synthetic paper, etc. can be listed. The adhesive sheet substrate can be appropriately selected according to the purpose and environment of the adhesive sheet.

[0053] The adhesive in the adhesive layer 50 of this embodiment is not particularly limited. For example, rubber, acrylic, silicone, epoxy, polyester, polyurethane, polyolefin, vinyl ether or biomass adhesives containing biomass-derived materials can be listed. However, from the perspective of reducing environmental load, biomass adhesives are preferred.

[0054] Figure 6 This is a comparison photo of the sheets obtained after using release papers made by two different embossing methods to make synthetic leather. Figure 6 (a) uses rubber to wool embossing method, Figure 6In (b), steel-on-steel embossing is used. Compared to steel-on-steel embossing, the rubber-on-wool embossing method, which uses a wool roller, can create a deeper pattern. However, the highly elastic wool roller tends to widen the spacing between the concave and convex parts of the concave-convex structure.

[0055] Finally, it should be noted that the above embodiments are only specific embodiments of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them, and the scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that any person familiar with the technical field can still modify the technical solutions described in the aforementioned embodiments or easily conceive of changes within the technical scope disclosed in the present invention, or perform equivalent replacements on some of the technical features therein. These modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A release paper, characterized in that: The paper substrate, barrier layer and release agent layer are stacked in sequence. A concavo-convex structure is formed on the exposed surface of the release agent layer. The concavo-convex structure is formed on a surface of the barrier layer in contact with the release agent layer.

2. The release paper according to claim 1, characterized in that The concavo-convex structure is formed on the exposed surface of the paper substrate.

3. The release paper according to claim 1 or 2, characterized in that: In the concavo-convex structure, a distance between two adjacent concave portions is greater than or equal to 0.5 mm and less than 5 mm.

4. The release paper according to claim 1 or 2, characterized in that: The release agent in the release agent layer is a silicone resin.

5. The release paper according to claim 1 or 2, characterized in that: The basis weight of the paper substrate is 30 g / m 2 ~300g / m 2 .

6. The release paper according to claim 1 or 2, characterized in that: The thickness of the release agent layer is 0.01 μm to 10 μm.

7. An adhesive sheet, characterized in that: The release paper according to any one of claims 1 to 6 is laminated in this order.

8. The adhesive sheet according to claim 7, wherein The concavo-convex structure of the release agent layer is transferred onto the surface of the adhesive layer.

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