Release liner, laminate including the release liner, and method for applying the laminate

Abstract

A release liner capable of reducing or suppressing the generation of paper dust and the like when cutting the release liner. The release liner includes, in order, a release layer, a first resin layer, a paper base material, and a second resin layer. The paper base material contains recycled pulp, and the release liner has an internal bond strength of approximately 45.0 N / m or greater.

Description

Description Title of InventionRELEASE LINER, LAMINATE INCLUDING THE RELEASE LINER, AND METHOD FOR APPLYING THE LAMINATETechnical Field

[0001] The present disclosure relates to a release liner, a laminate including the release liner, and a method for applying the laminate.Background Art

[0002] Release liners including paper substrates have been developed.

[0003] Patent Document 1 (JP 2012-224952 A) describes a release paper in which, by providing a sealing coating layer and a release layer sequentially on a base paper mainly made of wood pulp, and providing a back face coating layer on the face opposite to the release layer, curls at both end portions occur toward the back face layer by 2 mm or greater on average at a relative humidity of 20% when the release paper, which is 20 mm in the vertical direction and 210 mm in the horizontal direction, is placed on a horizontal face with the back face layer side facing up and is subjected to humidity control in an environment at 23°C and a relative humidity of 20% for 10 hours and then maintained in an environment at 23°C and a relative humidity of 80% for 10 hours.

[0004] Patent Document 2 (W O 2020 / 110689) describes a release paper including: a paper base material; a sealing layer on one face or both faces of the paper base material, the sealing layer containing a biomass-derived resin and / or a biodegradable resin; and a release layer on at least one side of the sealing layer.Citation ListPatent Document

[0005] Patent Document 1: JP 2012-224952 APatent Document 2: WO 2020 / 110689Summary of Invention Technical Problem

[0006] The inventors of the present invention attempted to employ a paper base material containing recycled pulp as a base material for a release liner from the viewpoint of sustainability.

[0007] However, for example, when a release liner is cut by using a cutter exclusively for use for release liners, as the cutting ability of such a cutter deteriorates, using a paper base material containing recycled pulp has been found to cause, for example, failures such as paper dust and fluffing (also simply referred to as “paper dust” or “paper dust and the like”) in a cross section of the cut portion and the like. For example, when only a release liner of a laminate including the release liner and a decorative sheet iscut and pressure-bonded to a wall surface or the like, and then the release liner is peeled, paper dust and the like is attached to an adhesive face, and as a result, the generation of the paper dust and the like may cause failures such as appearance failure due to recesses and protrusions of a sheet surface after the application.

[0008] The present disclosure provides a release liner capable of reducing or suppressing generation of paper dust and the like at the time of cutting of the release liner.Solution to Problem

[0009] According to an embodiment of the present disclosure, a release liner including, in order, a release layer, a first resin layer, a paper base material, and a second resin layer, the paper base material containing recycled pulp, and the release liner having an internal bond strength of approximately 45.0 N / m or greater, is provided.

[0010] According to another embodiment of the present disclosure, a laminate including the release liner and a decorative sheet disposed on the release layer of the release liner by interposing an adhesive layer is provided.

[0011] According to another embodiment of the present disclosure, a method for applying the laminate described above to a support member is provided. The method includes forming a cut portion by cutting the release liner along at least partially in a length direction of the release liner of the laminate using a cutter, exposing the adhesive layer by peeling at least a part of the release liner along the cut portion, and applying the exposed adhesive layer to the support member.Advantageous Effects of Invention

[0012] According to the present disclosure, a release liner capable of reducing or suppressing generation of paper dust and the like at the time of cutting of the release liner can be provided.

[0013] The above description is not to be construed as having disclosed all the embodiments of the present invention nor all the advantages related to the present invention.Brief Description of Drawings

[0014] FIG. 1 is a schematic cross-sectional view of a release liner of an embodiment of the present disclosure.FIG. 2 is a schematic cross-sectional view of a laminate including a release liner and a decorative sheet of an embodiment of the present disclosure.FIG. 3 is a photograph related to paper dust generated when a release liner is cut by using a cutter.FIG. 4(a) is a drawing illustrating dimension and the like of plain copy paper used in a test to measure the cutting ability of a cutter. FIG. 4(b) is a photograph related to a measurement device and a measurement method used in the test to measure the cutting ability of a cutter.FIG. 5(a) is a photograph of a condition of a test piece set in a tensile tester of an internal bond strength test of a release liner, and FIG. 5(b) is a schematic drawing illustrating the condition of the test piece in FIG. 5(a).FIG. 6 is a schematic drawing of the state in which a part of a release liner in a laminate including the release liner and a decorative sheet of an embodiment of the present disclosure is cut, and the decorative sheet is applied to a support member by interposing an adhesive layer.Description of Embodiments

[0015] Below, with an object of illustrating typical embodiments of the present invention, more detailed description will be given with reference to the drawings as necessary; however, the present invention is not limited to these embodiments.

[0016] In the present disclosure, the term “on”, for example used in “a release layer disposed on a first resin layer” means that the release layer is disposed directly on the upper side of the first resin layer, or that the release layer is indirectly disposed on the upper side of the first resin layer via another layer.

[0017] In the present disclosure, the term “under”, for example used in “a paper base material disposed under a first resin layer” means that the paper base material is disposed directly at the lower side of the first resin layer, or that the paper base material is indirectly disposed at the lower side of the first resin layer via another layer.

[0018] In the present disclosure, the term “in order”, for example used in “including, in order, a release layer, a first resin layer, a paper base material, and a second resin layer”, means that, when four components that are the release layer, the first resin layer, the paper base material, and the second resin layer are focused, a release liner or a laminate including the liner contains these components in this order, and another layer such as a printed layer may be interposed between these components, such as between the first resin layer and the paper base material.

[0019] In the present disclosure, the term “sheet” encompasses members referred to as “films”.

[0020] In the present disclosure, the term “(meth)acrylic” refers to acrylic or methacrylic, and the term“(meth)acrylate” refers to acrylate or methacrylate.

[0021] A schematic cross-sectional view of a release liner of an embodiment of the present disclosure is illustrated in FIG. 1. A release liner 100 in FIG. 1 includes, in order, a release layer 103, a first resin layer 105, a paper base material 107, and a second resin layer 109.

[0022] The release liner of the present disclosure has an internal bond strength of approximately 45.0 N / m or greater determined by the internal bond strength test of the release liner described below. Since the release liner of the present disclosure has such an internal bond strength that, when the release liner is cut, paper dust and the like do not scatter in surroundings and are held in a liner inner part, and thus generation of paper dust and the like can be reduced or suppressed. The internal bond strength of the release liner is preferably approximately 48.0 N / m or greater, approximately 50.0 N / m or greater, approximately 53.0 N / m or greater, or approximately 55.0 N / m or greater, from the viewpoint of reducing or suppressing generation of paper dust and the like at the time of cutting. The upper limit of the internal bond strength can be, for example, approximately 100 N / m or less, approximately 90.0 N / m or less,approximately 80.0 N / m or less, approximately 70.0 N / m or less, approximately 65.0 N / m or less, approximately 63.0 N / m or less, or approximately 60.0 N / m or less.

[0023] The internal bond strength of the release liner can be adjusted by, for example, recycled pulp blended in the paper base material described below. The strength can be adjusted based on, for example, the fiber size and the fiber length of the recycled pulp. When the internal bond strength test is performed for the release liner, typically, the release liner is separated into two in a manner that the release liner is tom in a layer of the paper base material but not in an interface between the first resin layer or the second resin layer and the paper base material (FIG. 5(b)). Thus, in other words, the internal bond strength of the release liner is an intralayer bond strength of the paper base material. Furthermore, it can be said that the internal bond strength of the release liner indirectly defines parameters (e.g., fiber size and fiber length) related to pulp (e.g., recycled pulp) in the paper base material because the internal bond strength can be adjusted by fiber size and the like of the recycled pulp.

[0024] The release layer in the release liner of the present disclosure is not particularly limited. Examples of the release agent that can be used for the release layer include a silicone-based release agent or a fluorine -based release agent, or a release agent containing an alkyd resin, a long-chain alkyl-based resin, and various waxes. The release agent may be a biodegradable release agent. In particular, from the viewpoint of releasing characteristics, the release agent preferably contains a silicone -based release agent. The release agent may be used alone or in combination of two or more types. The release agent may be, for example, in any form selected from solvent type, solventless type, or emulsion type, but preferably is an emulsion type or solventless type release agent from the viewpoint of environment and the like.

[0025] Examples of the resin that can be used in a silicone -based release agent include a homopolymer or copolymer of trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, diphenyldichlorosilane, phenyltrichlorosilane, and methylvinyldichlorosilane. These resins can be used alone, or two or more thereof can be used in combination.

[0026] The thickness of the release layer is not particularly limited. The thickness can be, for example, approximately 0.01 micrometers or greater, approximately 0.05 micrometers or greater, approximately 0. 1 micrometers or greater, approximately 0.5 micrometers or greater, or approximately 1 micrometer or greater, and can be approximately 10 micrometers or less, approximately 7 micrometers or less, approximately 5 micrometers or less, or approximately 3 micrometers or less. Here, the thickness of the release layer is an average value of thicknesses for at least 5 freely chosen points in a release layer of a release liner determined by measuring a cross section in a thickness direction of the release liner of a laminate structure by using a scanning electron microscope. The measurement method of the thickness can be used similarly for thickness of each layer constituting a release liner and a laminate including the liner.

[0027] The method of applying the release agent to the first resin layer is not particularly limited. As such a method, for example, a known method, such as blade coating, air-knife coating, rod blade coating, bar blade coating, gravure coating, bar coating, roll coating, and spray coating, can be appropriately employed. In FIG. 1, the release layer is applied to the first resin layer; however, also, the release layermay be applied to the second resin layer. As a method for applying the release layer to a second resin layer, an application method for the first resin layer can be similarly employed.

[0028] The first resin layer in the release liner of the present disclosure is typically a layer positioned in between a release layer 103 and a paper base material 107 as illustrated in FIG. 1, and is a layer positioned on a side to which a decorative sheet 201 and the like is applied as illustrated in FIG. 2. The first resin layer may have a single layer structure or a multilayered structure. Note that the first resin layer can be called a “filling layer” because the first resin layer can achieve a performance to suppress infiltration of a release agent into a paper base material when the release agent is applied to the paper base material. In a case where the first resin layer has a multilayered structure, the entire layers thereof can be referred to as “first resin layer group”.

[0029] The raw material of the first resin layer is not particularly limited. Examples of the raw material include a polyolefin resin, such as polyethylene, polypropylene, and polymethylpentene, a (meth)acrylic resin, a silicone resin, an alkyd resin containing an amino alkyd, a polyvinyl alcohol, a styrene acrylic resin, a cellulose derivative, a polyester resin, a resin containing a urethane bond, a melamine resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, and an epoxy resin. Here, in the present disclosure, the term “resins having urethane bonds” may include, for example, a resin prepared using at least one selected from urethane (meth)acrylate and urethane (meth)acrylate oligomer besides a urethane resin, and the urethane resin can also include a (meth)acrylic urethane resin, and the like. Among these raw materials, from the viewpoint of reducing or suppressing generation of paper dust and the like at the time of cutting of the release liner, a polyolefin resin is preferred, and polyethylene is more preferred. The raw material of the first resin layer can be used alone, or in combination of two or more.

[0030] The thickness of the first resin layer is not particularly limited. The thickness can be, for example, approximately 0.5 micrometers or greater, approximately 1 micrometer or greater, approximately 3 micrometers or greater, approximately 5 micrometers or greater, or approximately 10 micrometers or greater, and can be approximately 50 micrometers or less, approximately 40 micrometers or less, approximately 30 micrometers or less, or approximately 20 micrometers or less. In a case where the first resin layer is a multilayered structure, the thickness of each constituent layer may be in such a thickness range, or the thickness of the entire first resin layer may be in such a thickness range.

[0031] The method of applying the first resin layer to the paper base material is not particularly limited. As such a method, for example, a known method, such as extrusion coating, blade coating, airknife coating, rod blade coating, bar blade coating, gravure coating, bar coating, roll coating, and spray coating, can be appropriately employed.

[0032] The paper base material in the release liner of the present disclosure contains recycled pulp. The recycled pulp content in the paper base material can be, for example, approximately 30 mass% or greater, approximately 35 mass% or greater, approximately 40 mass% or greater, approximately 50 mass% or greater, or approximately 60 mass% or greater, and can be approximately 100 mass% or less, or less than approximately 100 mass%, with respect to the total amount of the paper base material. As described above, even in a case where the paper base material contains a high recycled pulp content,when the internal bond strength of the release liner is approximately 45.0 N / m or greater, generation of paper dust and the like at the time of cutting of the release liner can be reduced or suppressed. The paper base material may have a single layer structure or a multilayered structure.

[0033] In the present disclosure, “recycled pulp” can mean pulp regenerated from wastepaper. Examples of the recycled pulp can include, for example, wastepaper pulp obtained by defiberizing wastepaper, and deinked pulp obtained by removing ink after wastepaper is defiberized. Examples of the wastepaper used as the raw material include newspapers, leaflets, magazines, books, office papers, sealed letters, heat-sensitive papers, carbonless copy papers, corrugated cardboards, white paperboards, printed papers produced by copiers or office automation equipment. Magazine wastepaper containing a tacky material, such as a tacky adhesive, an adhesive agent, an adhesive tape, and bookbinding glue of magazines, can be also used as a raw material of the recycled pulp. These recycled pulp obtained by such raw materials can be used alone, or in combination of two or more.

[0034] For the recycled pulp, as necessary, for example, sodium hydroxide, sodium silicate, other alkali chemicals, a deinking agent, an acidic bleaching agent, and a reducing bleaching agent can be applied. In addition, for the recycled pulp, as necessary, for example, a dye, a fluorescent brightening agent, a pH adjusting agent, an antifoaming agent, a pitch controlling agent, and a slime controlling agent can also be applied.

[0035] When deinking is performed for wastepaper, a deinking agent can be used. Examples of the deinking agent include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants of fatty acid salts, higher alkyl sulfates, alkylbenzene sulfonates, higher alcohols, alkyl phenols, and alkylene oxide adducts of fatty acids; and organic solvents, proteins, enzymes, natural polymers, and synthetic polymers.

[0036] Wastepaper that is used as a raw material of the recycled pulp may contain inorganic particles called ashes. The ashes refer to inorganic particles in general and can be substances remained after paper, in which a loading material, a pigment, and the like are added or coated during production of the paper, is subjected to ashing. Examples of the inorganic particles include calcium carbonate, talc, kaolin, and titanium dioxide. From the viewpoint of reducing or suppressing generation of paper dust and the like at the time of cutting of the release liner, in the paper base material of the present disclosure, the inorganic particle content in the paper base material is preferably approximately 10 mass% or less, approximately 5 mass% or less, approximately 3 mass% or less, approximately 1 mass% or less, approximately 0.5 mass% or less, or approximately 0.1 mass% or less, with respect to the total amount of the paper base material, and more preferably the inorganic particles are not contained in the paper base material.

[0037] In some embodiments, the paper base material of the present disclosure can contain pulp (e.g., natural pulp originated from a plant) other than the recycled pulp. Examples of the pulp include softwood or hardwood kraft pulp (NKP or LKP); softwood or hardwood-based mechanical pulp such as groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), chemigroundwood pulp (CGP), and semichemical pulp (SCP). The pulp other than the recycled pulp can be used alone, or in combination of two or more types thereof.

[0038] The pulp content not including the recycled pulp in the paper base material can be, for example, approximately 70 mass% or less, approximately 65 mass% or less, approximately 60 mass% or less, approximately 50 mass% or less, approximately 40 mass% or less, approximately 30 mass% or less, approximately 20 mass% or less, or approximately 10 mass% or less, with respect to the total amount of the paper base material. The lower limit of the content can be, for example, approximately 0 mass% or greater or greater than approximately 0 mass%.

[0039] As the internal bond strength of the release liner can be said to be the intralayer bond strength of the paper base material as described above, the internal bond strength can be adjusted by the fiber size, the fiber length, and the like of the recycled pulp and virgin pulp other than the recycled pulp blended in the paper base material. Note that, in a case where the paper base material is formed by using a mixed slurry of recycled pulp and virgin pulp, distinguishing the recycled pulp from the virgin pulp in the obtained paper base material by using means such as an electron microscope is often difficult. Because it can be said that the internal bond strength of the release liner of the present disclosure indirectly defines parameters (e.g., fiber size and fiber length of the pulp) related to the pulp in the paper base material (e.g., papermaking base material), the internal bond strength can be said to be a suitable parameter to specify the paper base material, especially a paper base material in a mixed form of the recycled pulp and the virgin pulp. Therefore, values of the fiber size and the fiber length of the pulp blended in the paper base material can be appropriately set in a manner that the internal bond strength of the release liner is within the predetermined range.

[0040] The basis weight of the paper base material can be, for example, approximately 10 g / m2or greater, approximately 20 g / m2or greater, approximately 30 g / m2or greater, approximately 40 g / m2or greater, approximately 50 g / m2or greater, or approximately 60 g / m2or greater, and can be approximately 150 g / m2or less, approximately 130 g / m2or less, approximately 100 g / m2or less, or approximately 90 g / m2or less.

[0041] The method of producing the paper base material of the present disclosure is not particularly limited. The paper base material can be produced by a known paper-making method by using a pulp slurry containing recycled pulp and the like.

[0042] In the paper base material, an optional additive (e.g., sizing agent, yield improver, and paper strengthening agent) that is ordinarily used in paper production can be appropriately blended as necessary. In some embodiments, the paper base material of the present disclosure contains a paper strengthening agent. Examples of the paper strengthening agent include a (meth)acrylamide-based paper strengthening agent containing a component related to a (meth)acrylamide as a constituent unit of a polymer. The compounded amount of the paper strengthening agent, in terms of solid content, is approximately 5 mass% or less, approximately 3 mass% or less, approximately 1 mass% or less, approximately 0.5 mass% or less, or approximately 0.1 mass% or less, with respect to the pulp solid content of the paper base material.

[0043] The second resin layer in the release liner of the present disclosure is typically a layer positioned on a side opposite to the first resin layer 105 with respect to the paper base material 107 as illustrated in FIG. 1. For example, the second resin layer has a performance to protect the paper basematerial. Furthermore, in some embodiments, the second resin layer is a layer positioned on a side opposite to the decorative sheet 201 as illustrated in FIG. 2, and is a layer that is cut first by a cutter when the laminate 200 of FIG. 2 is applied by adhering to an adherend. When the second resin layer is disposed for the paper base material, generation of paper dust and the like can be reduced or suppressed at the time of cutting of the release liner compared to a case of a release liner that does not include the resin layer. The second resin layer may have a single layer structure or a multilayered structure. Note that, in a case where the second resin layer has a multilayered structure, the entire layers thereof can be referred to as “second resin layer group”.

[0044] The raw material of the second resin layer is not particularly limited, and a raw material similar to that of the first resin layer described above can be used. The method for applying the second resin layer to the paper base material is also not particularly limited, and an application method similar to that of the first resin layer described above can be employed.

[0045] The thickness of the second resin layer is not particularly limited. The thickness can be, for example, approximately 0.5 micrometers or greater, approximately 1 micrometer or greater, approximately 3 micrometers or greater, approximately 5 micrometers or greater, or approximately 10 micrometers or greater, and can be approximately 50 micrometers or less, approximately 40 micrometers or less, approximately 30 micrometers or less, or approximately 20 micrometers or less. In a case where the second resin layer is a multilayered structure, the thickness of each constituent layer may be in such a thickness range, or the thickness of the entire second resin layer may be in such a thickness range.

[0046] The thickness of the release liner of the present disclosure can be various thicknesses depending on the handling and usage. The thickness can be, for example, approximately 200 micrometers or less, approximately 180 micrometers or less, approximately 150 micrometers or less, or approximately 145 micrometers or less, and can be approximately 50 micrometers or greater, approximately 70 micrometers or greater, approximately 100 micrometers or greater, approximately 110 micrometers or greater, or approximately 120 micrometers or greater. The thickness of the entire release liner may be defined, for example, as an average value of thicknesses of at least any five points on the release liner measured with a thickness gauge (PC-465N, available from TECLOCK).

[0047] In place of the thickness, the release liner of the present disclosure can be defined by the basis weight. The basis weight can be, for example, approximately 200 g / m2or less, approximately 180 g / m2or less, approximately 150 g / m2or less, approximately 140 g / m2or less, approximately 130 g / m2or less, or approximately 120 g / m2or less, and can be approximately 50 g / m2or greater, approximately 60 g / m2or greater, approximately 70 g / m2or greater, approximately 80 g / m2or greater, approximately 90 g / m2or greater, or approximately 100 g / m2or greater.

[0048] The release liner of the present disclosure can reduce or suppress generation of paper dust and the like at the time of cutting. For example, when only a release liner of a laminate including the release liner and a decorative sheet is cut and pressure-bonded to a wall surface or the like, and then the release liner is peeled, paper dust and the like is attached to an adhesive face, and as a result, the generation of the paper dust and the like may cause failures such as appearance failure due to recesses and protrusions of adecorative sheet surface after the application. Since the release liner of the present disclosure can improve such failures, the release liner can be suitably used for a decorative sheet.

[0049] The release liner of the present disclosure can provide a laminate by application of an optional component to the release layer of the liner. Examples of the optional component include a decorative sheet. For example, the decorative sheet can be disposed on a release layer 203 of the release liner by interposing an adhesive layer 202 therebetween as illustrated in FIG. 2. The arrangement of the decorative sheet on the release layer can be performed by adhering the decorative sheet after the adhesive layer is applied to the release layer or by adhering the decorative sheet after the decorative sheet is applied to the adhesive layer by interposing the adhesive layer between the decorative sheet and the release layer.

[0050] The adhesive layer can be released from the release layer and is typically a layer applied to an adherend, such as a support member described below, together with the decorative sheet.

[0051] The raw material of the adhesive layer is not particularly limited and, for example, a typically used adhesive agent can be used, such as a solvent, emulsion, pressure-sensitive, heat-sensitive, thermosetting, or ultraviolet-curable adhesive agent of (meth)acrylic, polyolefin, polyurethane, polyester, or rubber. Among these, from the viewpoint of workability and reworkability of the decorative sheet, a pressure -sensitive adhesive agent is preferred.

[0052] The raw material of the pressure -sensitive adhesive agent is not particularly limited, and for example, (meth)acrylic polymers, natural rubbers, synthetic rubbers, polyester-based polymers, polyether- based polymers, polyurethane-based polymers, silicone-based polymers, or other polymers can be used. Among these, a pressure-sensitive adhesive agent of (meth)acrylic polymer is preferred because of excellent transparency, weather resistance, and adhesiveness.

[0053] As optional components, the adhesive layer can contain, for example, tackifying resins, crosslinking agents, fillers such as electrically conductive fillers and thermally conductive fillers, silane coupling agents, plasticizers, thickeners, pigments, dyes, flame retardants, antioxidants, UV absorbing agents, and stabilizers. The optional components can be used alone, or in combination of two or more types thereof.

[0054] The thickness of the adhesive layer is not particularly limited and, for example, can be approximately 5 micrometers or greater, approximately 10 micrometers or greater, or approximately 20 micrometers or greater, and can be approximately 100 micrometers or less, approximately 80 micrometers or less, or approximately 50 micrometers or less.

[0055] The decorative sheet includes a decorative layer. Examples of the decorative layer include, but are not limited to, a color layer that exhibits a paint color, for example, a light color, such as white or yellow, and a deep color, such as red, brown, green, blue, gray, or black; a pattern layer that imparts a design pattern, such as a wood grain, a stone grain, a geometric pattern, or a leather pattern, a logo, a drawing, a character, a number, a symbol, a photograph, or a picture pattern on an article; a relief (embossed pattern) layer in which an uneven shape is provided on the surface; and combinations of these layers. The decorative layer may have a single layer structure or a layered structure.

[0056] The decorative layer can be applied to, but is not limited to, an entire surface of or a part of a surface layer described later, directly or indirectly via the bonding layer or the like.

[0057] The raw material for the color layer is not limited to the following, but for example, a raw material obtained by dispersing a pigment in a binder resin can be used. Examples of the pigment include inorganic pigments, such as carbon black, chrome yellow, yellow iron oxide, colcothar, or red iron oxide; or organic pigments, such as a phthalocyanine pigment such as phthalocyanine blue or phthalocyanine green, an azo lake pigment, an indigo pigment, a perinone pigment, a perylene pigment, a quinophthalone pigment, a dioxazine pigment, and a quinacridone pigment such as quinacridone red. The binder resin can be used alone, or in combination of two or more. Examples of such resins include thermoplastic resins, thermosetting resins, and radiation curable resins. Specific examples thereof include fluorine-based resins, polyester-based resins such as PET and PEN, (meth)acrylic resins, polyolefin-based resins such as polyethylene and polypropylene, thermoplastic elastomers, polycarbonate resins, polyamide resins, ABS resins, acrylonitrile-styrene resins, polystyrene resins, vinyl chloride resins, and resins having a urethane bond. Of these, vinyl chloride resins are preferable from the viewpoint of flame retardance and the like. Here, in the present disclosure, the “vinyl chloride resin” may include, in addition to a homopolymer of vinyl chloride, a copolymer of a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer. As the other monomer copolymerizable with the vinyl chloride monomer, known monomers commonly used may be used without any particular limitation. Examples thereof include one or a mixture of two or more of vinyl esters such as vinyl acetate, alkyl vinyl ethers such as ethyl vinyl ether and octyl vinyl ether, a-olefins such as ethylene and propylene, monovalent unsaturated acids such as acrylic acid and methacrylic acid, and alkyl esters such as methyl esters of these monovalent unsaturated acids, divalent unsaturated acids such as maleic acid and itaconic acid, alkyl esters such as methyl esters of these divalent unsaturated acids, vinylidene compounds such as vinylidene chloride, and unsaturated nitriles such as acrylonitrile. The proportion of these monomers used is not particularly limited, and for example, they may be used in a proportion of about 30 mass% or less or about 20 mass% or less with respect to the vinyl chloride monomer.

[0058] The color layer can be formed using such a raw material, for example, by a coating method, such as gravure coating, roll coating, die coating, bar coating, or knife coating.

[0059] The pattern layer is not limited to the following but, for example, a pattern layer obtained by directly applying a pattern, such as a design pattern, a logo, or a picture pattern, on the surface layer described later or the like using a printing method, such as gravure direct printing, gravure offset printing, inkjet printing, laser printing, or screen printing, may be employed. Alternatively, for example, a film or a sheet having a design pattern, a logo, a picture pattern, or the like formed by coating, such as gravure coating, roll coating, die coating, bar coating, or knife coating, punching, or etching can be also used. For example, a raw material similar to those used in the color layer can be used for the pattern layer.

[0060] For the relief layer, a thermoplastic resin film having an uneven shape on the surface may be used, the uneven shape being obtained by a well-known method in the art, such as, for example, emboss finishing, scratch processing, laser processing, dry etching processing, or hot press processing. The relief layer may be also formed by applying a thermosetting or radiation-curable resin, such as a curable (meth)acrylic resin, on a release liner having an uneven shape, curing the resin by heat or radiation, and removing the release liner.

[0061] The thermoplastic resin, thermosetting resin, and radiation-curable resin used in the relief layer are not particularly limited but, for example, a fluororesin, a polyester resin such as PET or PEN, a (meth)acrylic resin, a polyolefin resin such as polyethylene or polypropylene, a thermoplastic elastomer, polycarbonate, polyamide, an ABS resin, an acrylonitrile-styrene resin, polystyrene, vinyl chloride, or a resin having a urethane bond can be used. Among these, for example, from the perspective of impact resistance, a resin having a urethane bond is preferred. The relief layer may include at least one type of pigment used in the color layer.

[0062] The thickness of the decorative layer is to be appropriately adjusted according to the required decorativeness or the like and is not particularly limited. The thickness can be, for example, approximately 1 micrometer or greater, approximately 3 micrometers or greater, or approximately 5 micrometers or greater, and approximately 200 micrometers or less, approximately 150 micrometers or less, or approximately 100 micrometers or less.

[0063] The decorative sheet of the present disclosure may include any additional configuration. Examples of the additional configuration include at least one selected from the group consisting of a surface layer, a bonding layer, and a middle film layer. The additional configuration can be applied to the entire surface or a portion of the decorative sheet.

[0064] In some embodiments, the decorative sheet of the present disclosure includes a surface layer. The raw material of the surface layer is not particularly limited, and for example, one type of or a blend of two or more types of (meth)acrylic resins such as polymethyl methacrylate (PMMA) and (meth)acrylic copolymers, resins having a urethane bond (e.g., polyurethane), fluororesins such as ethylenetetrafluoroethylene copolymers (ETFE), polyvinylidene fluoride (PVDF), methyl methacrylate-vinylidene fluoride copolymers (PMMA / PVDF), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), silicone resins, polyvinyl chloride (PVC), polycarbonate (PC), polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamides such as nylon, and copolymers such as ethylene / acrylic acid copolymers (EAA) and ionomers thereof, ethylene -ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, and ethylene -vinyl alcohol copolymers (EVOH) can be used. The surface layer may have a single layer structure or a multi-layer structure. For example, the surface layer may be a laminate of films formed from the resins described above, or may be a multilayer coating of the resins described above. The surface layer may have a three-dimensional uneven shape such as an embossed pattern on the entirety or part of the surface thereof.

[0065] The surface layer can be formed by coating the decorative layer with a resin composition directly or via the bonding layer or the like. The coating of the surface layer can be performed before application or after application of the decorative sheet to the adherend. Alternatively, a surface layer film can be formed by coating the release liner with the resin composition, and the film can be laminated on the decorative layer directly or via the bonding layer or the like. For example, the surface layer film can be formed by coating a release liner with a resin raw material such as a curable (meth)acrylic resin composition or a reactive polyurethane composition by knife coating, bar coating, blade coating, doctor coating, roll coating, or cast coating, and then light or heat curing as necessary.

[0066] A surface layer formed into a film beforehand through extrusion, stretching, and the like may be used. Such a film can be laminated on the decorative layer directly or via the bonding layer or the like. By using a film with high flatness as the film, an article (laminate) can be given an appearance of higher surface flatness. The surface layer can be formed by multilayer extrusion with other layers. For example, a (meth)acrylic film can be used as the other layer. For example, a resin containing polymethyl methacrylate (PMMA), butyl polyacrylate, (meth)acrylic copolymer, ethylene / acrylic copolymer, ethylene vinyl acetate / acrylic copolymer can be formed into a film and used as the (meth)acrylic film. The (meth)acrylic film is excellent in transparency and / or scratch resistance, resistant to heat and / or light, and less likely to cause discoloration and / or changes in gloss. In addition, excellent molding processability is achieved without use of a plasticizer, and excellent contamination resistance is also achieved because use of plasticizer is not required. Among these, a (meth)acrylic film having PMMA as the main component is preferred. For example, in a case where a (meth)acrylic resin having excellent scratch resistance or the like is used as such another layer and a fluororesin having excellent chemical resistance or the like, such as ETFE, PVDF, or PMMA / PVDF, as the surface layer, the formed surface layer can be a surface layer having both performances of these layers.

[0067] The surface layer may be transparent, or partially translucent or opaque. From the perspective of visibility of the decorative layer, for example, the surface layer is preferably transparent.

[0068] The thickness of the surface layer may vary, and, for example, may be approximately 1 micrometer or more, approximately 5 micrometers or more, approximately 10 micrometers or more, approximately 20 micrometers or more, or approximately 30 micrometers or more, and may be approximately 200 micrometers or less, approximately less than 200 micrometers, approximately 180 micrometers or less, approximately 150 micrometers or less, approximately 130 micrometers or less, approximately 100 micrometers or less, or approximately 80 micrometers or less.

[0069] In the decorative sheet of the present disclosure, a bonding layer (sometimes referred to as a “primer layer”, for example) can be used to bond each layer constituting the decorative sheet.

[0070] The bonding layer can contain, for example, a resin having a urethane bond, a (meth)acrylic resin, an epoxy resin, a phenoxy resin, or a resin blend of two or more types of these.

[0071] The thickness of the bonding layer can be, for example, approximately 0.1 micrometers or more, approximately 0.2 micrometers or more, or approximately 0.5 micrometers or more, and approximately 10 micrometers or less, approximately less than 10 micrometers, approximately 5.0 micrometers or less, approximately 2.0 micrometers or less, approximately 1.0 micrometers or less, approximately 0.5 micrometers or less, or approximately less than 0.5 micrometers.

[0072] The decorative sheet may optionally include, for example, a middle fdm layer interposed between the surface layer and the decorative layer, or between the decorative layer and the adhesive layer. The middle film layer can enhance the strength of the decorative sheet.

[0073] As the middle film layer, for example, resin films of resins having a urethane bond, polyvinyl chlorides, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, (meth)acrylic polymers, or fluorochemical polymers can be used. The middle film layer preferably has thermoplasticity.

[0074] The thickness of the middle fdm layer can be, for example, approximately 5.0 micrometers or more, approximately 10 micrometers or more, or approximately 15 micrometers or more, and approximately 200 micrometers or less, approximately 100 micrometers or less, or approximately 50 micrometers or less.

[0075] Each layer constituting the decorative sheet may contain, as an optional component, a filler, an antioxidant, an ultraviolet absorber, a light stabilizer, a heat stabilizer, a hard coat material, a gloss imparting agent, a dispersant, a plasticizer, a flow improver, a surfactant, a leveling agent, a silane coupling agent, a catalyst, a pigment, a dye, and the like as long as the effect of the present invention is not adversely affected. The optional components can be used alone, or in combination of two or more types.

[0076] The application method of the laminate described above containing a decorative sheet disposed on a release layer of the release liner by interposing an adhesive layer between the decorative sheet and the release layer is not particularly limited. In some embodiments, the application method includes (1) forming a cut portion by cutting the release liner along at least partially in a length direction of the release liner of the laminate using a cutter, (2) exposing the adhesive layer by peeling at least a part of the release liner along the cut portion, and (3) applying the exposed adhesive layer to the support member. Note that “length direction of the release liner of the laminate” does not mean the thickness direction of the release liner, and can mean a freely chosen direction of a surface of the release liner, such as a length direction (long side direction) or a width direction (short side reaction) of the release liner. The release liner of the present disclosure can reduce or suppress generation of paper dust and the like at the time of cutting, and appearance failures caused by the generation of paper dust and the like can be reduced or suppressed, and thus the release liner can be suitably employed for the application method described above.

[0077] As the cutter to cut the release liner, for example, a cutter for a release liner can be used. Examples of the cutter for a release liner include a backing paper cutter. Such a cutter for a release liner typically has a structure that cuts a liner by a middle part of the cutter and, successively, spread the liner by a tip part of the cutter. Therefore, it is conceived that, when the cut is insufficient due to deterioration of cutting ability of the middle part of the cutter, paper dust tends to be generated due to paper tom by the tip part of the cutter. The release liner of the present disclosure can reduce or suppress generation of paper dust and the like even when such a cutter for a release liner is used.

[0078] The release liner of the present disclosure can be evaluated by a release liner cut test described below for the degree of generation of paper dust and the like. In this test, according to the chart for the estimation of contraries in JIS P8208, the size of paper dust and the like is classified into Group 1 (1.0 mm2or greater) and Group 2 (0.5 mm2or greater and less than 1.0 mm2). In some embodiments, the release liner of the present disclosure can suppress generation of paper dust and the like of Group 1 when the test is performed. That is, the number of Group 1 can be zero. The paper dust having a size of Group 1 tends to cause, for example, appearance failure of the decorative sheet; however, the release liner of the present disclosure can suppress paper dust and the like having such a size. In some embodiments, the release liner of the present disclosure can make the number of Group 2 to be 10 or less, 8 or less, 5 or less, or 4 or less. The lower limit of the number is not particularly limited but can be 0 or greater. Forexample, the paper dust having the size of Group 2 does not remarkably affect appearance failure of a decorative sheet compared to paper dust having the size of Group 1 ; however, when the amount of the paper dust having such a size is less, better appearance can be achieved.

[0079] The raw material of the support member to which the decorative sheet can be applied is not particularly limited. Examples of the raw material include resin raw materials (e.g., polyolefin resins, polyester resins, (meth)acrylic resins, polycarbonate resins, and acrylonitrile -butadiene -styrene copolymers), inorganic raw materials (e.g., glass, ceramic, concrete, gypsum, calcium silicate, natural stone, and asphalt), rubber raw materials, cloth materials (e.g., woven fabrics, knitted fabrics, and nonwoven fabrics), metal or metal alloy materials (e.g., iron, aluminum, and stainless steel), and woody raw materials including paper and the like.

[0080] The shape or structure of the support member is not particularly limited. The shape may be, for example, a plane shape (e.g., fdm shape or plate shape), curved surface shape, deformed shape, or three- dimensional shape, and the structure may be a single-layer structure, a laminated structure, or a composite structure in which a plurality of members having different shapes or materials are combined.

[0081] The laminate including the decorative sheet can be used for various purposes. Examples of such purposes include signboards (e.g., internally illuminated signboards and externally illuminated signboards); signs (e.g., internally illuminated signs and externally illuminated signs); various interior or exterior articles such as interior or exterior articles for vehicles, such as automobiles, railways, aircrafts, and ships (e.g., roof members; pillar members; door trim members; instrument panel members; front members, such as hoods; bumper members; fender members; side sill members; and interior panel members); and interior products or exterior products of buildings (e.g., window glass, doors, sashes, roof members such as tiling, outer wall members, and wall papers); electrical appliances, such as personal computers, smartphones, cellular phones, refrigerators, and air conditioners; stationery; furniture; desks; and various containers such as cans.Examples

[0082] In the following examples, specific embodiments of the present disclosure are illustrated, but the present invention is not limited to these embodiments. All 'part' and 'percent' are based on mass unless otherwise specified. A numerical value essentially includes an error originated from a measurement principle and a measuring device. The numerical value is generally indicated by a significant digit that is rounded.

[0083] «Examples 1 to 3 and Comparative Examples 1 to 3»<Example 1>On both faces of a paper base material containing approximately 40 mass% of recycled pulp and having a basis weight of approximately 70 g / m2, after a polyethylene resin layer having a thickness of approximately 20 micrometers was applied by extrusion coating, a silicone-based release layer having a thickness of approximately 1 micrometer was applied to one of the polyethylene resin layer by gravure coating, and thus a release liner having a total thickness of approximately 126 micrometers and a basis weight of approximately 109 g / m2was produced.

[0084] <Examples 2 and 3 and Comparative Examples 1 to 3>Each release liner of Examples 2 and 3 and Comparative Examples 1 to 3 was produced in the same manner as in Example 1 except for changing the recycled pulp content in the paper base material and the basis weight of the paper base material, and the total thickness and the basis weight of the release liner by adjusting the thickness of the polyethylene resin layer to those listed in Table 1.

[0085] <Physical Property Evaluation Test>The characteristics of the release liner and the inorganic particle content in the paper base material were evaluated by performing the following tests. The results are shown in Table 1.

[0086] (Internal bond strength test of release liner)The internal bond strength of the release liner was measured in accordance with JIS K 6854-2. The specific method of measurement is as follows.A test piece was produced by cutting the release liner into a size with a length of 150 mm and a width of 25 mm. From one of the resin layers of this test piece, the test piece was cut in a width direction in a manner that the blade of the cutter reached around the middle in a thickness direction of the paper base material. The resin layer and the cut paper base material was pulled from the cut position in a substantially 180 degrees direction, and thus a T-shaped test piece was produced. Edges of the resin layer and the cut paper base material of the test piece were set to chuck portions of a tensile tester (AGS-lkNG, available from Shimadzu Corp.) as illustrated in FIG. 5(a). The test piece was pulled at a speed of 300 mm / min in an environment at a temperature of 23°C and a humidity of 65%RH, and an average load after 50 mm peeling was measured. The test was performed three times, and an average value of the results thereof was used as the internal bond strength of the release liner. The results are shown in Table 1.

[0087] (Confirmation test of inorganic particle content in paper base material)The test piece produced in the same manner as for the internal bond strength test was cut into an approximately 1 cm square, and the cut test piece was adhered on an aluminum stage in a manner that the paper base material face was facing up by using an ordinary carbon tape. The surface observation of the paper base material was performed by using the SU3800 Plus II scanning electron microscope, available from Hitachi High-Tech Corporation, and Xplore 30 energy-dispersive X-ray spectroscopy, available from Oxford Instruments, (hereinafter, referred to as “EDS detector”) and focusing under the following conditions. For the data processing, analysis was performed by AZtecLive provided with the EDS detector. Note that, for all the samples, elementary analysis was performed for inorganic particles by fixing the magnification of the screen display to 100 times (measurement range: approximately 1.25 mm x approximately 1.0 mm rectangle) at an accumulated number of 30, and thus a mass percentage of the element in the measurement range was determined. The results are shown in Table 1.Measurement conditionsAcceleration voltage: 10 kVSpot intensity: 60Focal length (work distance): 10 mmDegree of vacuum (vacuum mode): 30 PaSurface sputtering treatment (sample treatment): noneVariable objective aperture (aperture): No. 1

[0088] (Release liner cut test)Paper dust and the like tend to occur as cutting ability of a cutter deteriorates. Thus, for this test, a cutter with a deteriorated cutting ability was used. Note that the cutting ability of the cutter was measured as described below, and a cutter having a load at the time of cutting paper of approximately 2.6 N / m was employed. Plain copy paper (PPC PAPER High White, available from Otsuka Corporation) having a basis weight of approximately 68 g / m2and a thickness of approximately 92 micrometers was cut into a size with a length of 10 cm and a width of 29 cm, and a 10 cm slit part was made in a longitudinal direction from a center of a 10 cm width of an edge portion as illustrated in FIG. 4(a). As illustrated in FIG. 4(b), the plain copy paper and a backing paper cutter (Guide Cutter, available from KLASS Corporation) were each disposed on upper and lower chuck portions of a tensile tester. Note that the backing paper cutter was disposed at the slit part of the prepared plain copy paper in a manner that the blade of the cutter was substantially linear to the cutting direction so that the plain copy paper can be cut by pulling the cutter. The average load when the cutter was pulled for 15 cm at a pulling speed of 300 mm / sec in an environment at a temperature of 23°C and a humidity of 65%RH was measured. The measurement was performed for three times, and the average value of the results thereof was used as a load at the time of cutting the paper.

[0089] Using the cutter described above, the release liner cut test was performed by the following procedure. A test piece was produced by cutting the release liner into a size with a length of 300 mm and a width of 210 mm. Subsequently, 3M (trade name) DI-NOC (trade name) fdm WG-157, which is a decorative sheet, (available from 3M Japan Limited (Shinagawa-ku, Tokyo, Japan)) was cut into a size with a length of 400 mm and a width of 300 mm, then the release liner of the fdm was peeled, and the release-treated face of the test piece was adhered to an adhesive face of the fdm. After the test piece was pressure -bonded by a squeegee, using the backing paper cutter, the test piece was cut for approximately 300 mm in a length direction at a speed of approximately 600 mm / min. This cutting operation was performed four times in total by shifting the cut positions (that is, 1200 mm was cut in total). After the test piece was pressure-bonded again by a squeegee, the test piece was removed, and the size of paper dust and the like attached to the adhesive face was classified as follows using the chart for the estimation of contraries of JIS P 8208, and the number of the paper dust and the like attached to the adhesive face was recorded based on the classification. The results are shown in Table 1.Size of paper dust and the likeGroup 1: 1.0 mm2or greaterGroup 2: 0.5 mm2or greater and less than 1.0 mm2

[0090] Table 1

[0091] It is apparent for a person skilled in the art that various variations of the embodiments and examples described above can be made without departing from the basic principles of the present invention. In addition, it is apparent for a person skilled in the art that various modifications and variations of the present invention can be made without departing from the spirit and scope of the present invention.Reference Signs List

[0092] 100 Release liner103, 203, 603 Release layer105, 205, 605 First resin layer107, 207, 607 Paper base material109, 209, 609 Second resin layer200 Laminate201, 601 Decorative sheet202, 602 Adhesive layer610 Cut portion611 Support member

Claims

Claims1. A release liner comprising, in order: a release layer; a first resin layer; a paper base material; and a second resin layer, wherein the paper base material comprises recycled pulp, and the release liner has an internal bond strength of 45.0 N / m or greater.

2. The release liner according to claim 1, wherein the paper base material comprises 30 mass% or greater of the recycled pulp.

3. The release liner according to claim 1 or 2, wherein a basis weight of the release liner is 200 g / m2or less.

4. The release liner according to claim 1 or 2, wherein a thickness of the release liner is 200 micrometers or less.

5. The release liner according to claim 1 or 2, wherein an inorganic particle content in the paper base material is 10 mass% or less.

6. The release liner according to claim 1 or 2, which is for a decorative sheet.

7. A laminate comprising a decorative sheet, the decorative sheet disposed on the release layer of the release liner according to claim 1 or 2 by interposing an adhesive layer.

8. A method for applying the laminate according to claim 7 to a support member, the method comprising: forming a cut portion by cutting the release liner along at least partially in a length direction of the release liner of the laminate using a cutter; exposing the adhesive layer by peeling at least a part of the release liner along the cut portion; and applying the exposed adhesive layer to the support member.

9. The application method according to claim 8, wherein the cutter is a cutter for a release liner.

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