Moisture-proof paper on the back of decorative panels

Abstract

To provide back surface moisture-proof paper for a decorative plate which can prevent warpage even when used in a place having a large difference between temperature and humidity environments on both sides.SOLUTION: There is provided back surface moisture-proof paper 10 for a decorative plate in which a paper base material 1 and a moisture-proof layer 20 are laminated, wherein the moisture-proof layer 20 is formed by laminating an anchor coat layer 2, a vapor-deposited layer 4 and an overcoat layer 5 in this order from a paper base material 1 side, the anchor coat layer 2 contains first polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride group and carboxylate, and the overcoat layer 5 contains second polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group and carboxylate, and the back surface moisture-proof paper has a resin layer 3 containing a polyvinyl alcohol-based resin between the paper base material 1 and the anchor coat layer 2 or between the anchor coat layer 2 and the vapor-deposited layer 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a moisture-proof backing paper for decorative panels. [Background technology]

[0002] Conventionally, decorative panels used for interior door panels and the like have generally been made by laminating a decorative sheet printed with a plain print layer for concealment or a patterned layer for design enhancement to the surface of a multilayered wood-based substrate, such as plywood, medium-density fiberboard (MDF), veneer, board, or other material. Warping of such decorative panels occurs due to moisture absorption and release caused by changes in indoor temperature and humidity. Specifically, if the moisture content of a wood-based substrate is lower than its equilibrium moisture content under outdoor conditions, moisture is absorbed from the side of the decorative panel not covered with the decorative sheet, causing the surface to expand. If the moisture content is higher than the equilibrium moisture content, moisture is released, causing shrinkage. In contrast, the side of the decorative panel covered with the decorative sheet exhibits almost no moisture absorption or release, resulting in deformation (warping, dimensional change) of the decorative panel.

[0003] To prevent this deformation, various methods are known, such as applying paint to the back of a decorative board with a decorative sheet attached to the surface, attaching a synthetic resin sheet such as polyvinyl chloride, polyethylene, or polypropylene, or attaching a moisture-proof sheet made of paper / polyethylene / paper. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3206408 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above method does not provide sufficient moisture resistance, and therefore, when used for a long period of time on doors, sliding doors, partitions, etc. where there is a large difference in temperature and humidity environment between the two sides, the degree of expansion and contraction on both sides may differ, causing warping.

[0006] The present invention has been made to solve the above unresolved problems, and aims to provide a moisture-proof paper for the back side of decorative panels that can prevent warping of the decorative panels even when used in places where there is a large difference in temperature and humidity environment between both sides. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, according to one aspect of the present invention, there is provided a backside moisture-proof paper for decorative panels, which is composed of a paper substrate and a moisture-proof layer laminated together, wherein the moisture-proof layer is composed of an anchor coat layer, a vapor deposition layer, and an overcoat layer laminated in this order from the paper substrate side, wherein the anchor coat layer contains a first polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride group, and a carboxylic acid ester, and the overcoat layer contains a second polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride group, and a carboxylic acid ester, and further wherein a resin layer containing a polyvinyl alcohol-based resin is provided between the paper substrate and the anchor coat layer or between the anchor coat layer and the vapor deposition layer. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to realize a moisture-proof paper for the back side of decorative panels that has significantly superior moisture-proof performance compared to conventional moisture-proof sheets made of synthetic resins such as polyvinyl chloride, polyethylene, polypropylene, etc., or paper / polyethylene / paper. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of a moisture-proof backside paper for decorative panels according to the present invention. [Figure 2]FIG. 4 is a cross-sectional view showing another example of the configuration of the moisture-proof backside paper for decorative panels according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] The drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of each thickness, etc., differ from the actual ones. Furthermore, the embodiments shown below are merely examples of configurations for embodying the technical idea of the present invention, and the technical idea of the present invention is not limited to the materials, shapes, etc. of the components described below. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims. <Moisture-proof paper on the back side of decorative panels>

[0012] FIG. 1 is a cross-sectional view showing a schematic example of the structure of a moisture-proof backside paper for decorative boards according to the present invention.

[0013] As shown in Figure 1, moisture-proof backside paper for decorative panels 10 is composed of a paper substrate 1, an anchor coat layer 2, a resin layer 3 containing a polyvinyl alcohol-based resin, a vapor deposition layer 4, and an overcoat layer 5 laminated in this order. The laminate consisting of the anchor coat layer 2, the resin layer 3 containing a polyvinyl alcohol-based resin, the vapor deposition layer 4, and the overcoat layer 5 forms a moisture-proof layer 20.

[0014] The anchor coat layer 2 contains a first polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

[0015] Similarly, the overcoat layer 5 contains a second polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

[0016] As shown in FIG. 2, the moisture-proof backside paper 10 for decorative sheets may have an adhesive primer layer 6 on the surface of the overcoat layer 5 opposite to the vapor-deposited layer 4 .

[0017] Next, the structure of each layer will be described. <Paper base material>

[0018] The paper substrate 1 is not particularly limited, and may be appropriately selected depending on the application of the moisture-proof backside paper 10 for decorative boards. Specific examples of the paper substrate 1 include tissue paper, fine paper, art paper, cast-coated paper, kraft paper, titanium paper, linter paper, paperboard, gypsum board paper, fine paper, coated paper, parchment paper, glassine paper, parchment paper, paraffin paper, and Japanese paper. As the paper substrate 1, tissue paper in which a synthetic resin is mixed to increase the strength between the sheets (so-called inter-sheet reinforced paper), or paper impregnated with latex or synthetic resin, is preferably used. The basis weight of the paper substrate 1 is not particularly limited, but is preferably 20 g / m 2 In the following cases, the paper base material 1 is too flexible and wrinkles are likely to occur during processing. 2 In the above cases, peeling between layers of the paper base material 1 is likely to occur, and problems such as peeling from the paper base material 1 are likely to occur. Therefore, the basis weight of the paper base material 1 is set to 20 g / m 2 More than 200g / m 2 Preferably less than 20 g / m 2 More than 100g / m 2 Preferably less than 20 g / m 2 More than 50g / m 2 The following is more preferred:

[0019] Furthermore, the paper substrate 1 may be subjected to surface treatment such as corona treatment, plasma treatment, or flame treatment as required.

[0020] The paper substrate 1 may also have a coating layer provided on at least the side that comes into contact with the anchor coat layer 2. The coating layer not only prevents the anchor coat layer 2 from penetrating into the paper substrate 1, but also serves as a sealant that fills in unevenness in the paper, allowing the anchor coat layer 2 to be formed uniformly and without defects. The coating layer may contain binder resins such as styrene-butadiene, styrene-acrylic, and ethylene-vinyl acetate copolymers, polyvinyl alcohol resins, cellulose resins, paraffin (wax), and the like, and fillers such as clay, kaolin, calcium carbonate, talc, and mica.

[0021] The thickness of the coating layer is not particularly limited, but is preferably, for example, 1 μm or more and 10 μm or less, and more preferably 3 μm or more and 8 μm or less.

[0022] The weight of the paper substrate 1 is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the weight of the entire moisture proof layer 20. If the weight of the paper substrate 1 is 50% by mass or more based on the weight of the entire moisture proof layer 20, the amount of plastic material used can be significantly reduced compared to conventional moisture proof sheets made of synthetic resins such as vinyl chloride, polyethylene, or polypropylene, or paper / polyethylene / paper, and the moisture proof paper 10 for decorative laminate backside can be said to be made of paper. <Anchor coat layer>

[0023] The anchor coat layer 2 is provided on the surface of the paper substrate 1 to improve adhesion between the paper substrate 1 and a resin layer 3 containing a polyvinyl alcohol-based resin. The anchor coat layer 2 contains a first polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester. Such an anchor coat layer 2 has excellent flexibility, which can suppress cracking of the vapor-deposited layer 4 and improve adhesion between the anchor coat layer 2 and the resin layer 3 containing a polyvinyl alcohol-based resin. Furthermore, the inclusion of the above-mentioned polyolefin makes it possible to form a dense film due to the carboxyl groups, etc., and to obtain a laminate with excellent water vapor barrier properties.

[0024] The anchor coat layer 2 may contain other components in addition to the first polyolefin, such as polyolefins other than the first polyolefin, silane coupling agents, organic titanates, polyacrylics, polyesters, polyurethanes, polycarbonates, polyureas, polyamides, polyimides, melamine, and phenols.

[0025] The content of the first polyolefin in the anchor coat layer 2 may be, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass.

[0026] The thickness of the anchor coat layer 2 may be, for example, 1 μm or more, more preferably 2 μm or more, and preferably 5 μm or less. If the thickness of the anchor coat layer 2 is 1 μm or more, the unevenness of the paper base material 1 described above can be efficiently filled, and the resin layer 3 containing a polyvinyl alcohol resin and the vapor deposition layer 4 can be laminated evenly. Furthermore, even if the thickness of the anchor coat layer 2 is greater than 5 μm, there is no problem in terms of moisture resistance, but if the thickness of the anchor coat layer 2 is 5 μm or less, the above layers can be laminated evenly while keeping costs down.

[0027] The anchor coat layer 2 can be provided by applying a coating liquid containing the above-mentioned polyolefin and solvent to the paper substrate 1 and drying it. Examples of solvents contained in the coating liquid include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used alone or in combination. Among these, from the viewpoint of properties, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred. Furthermore, from the viewpoint of environmental friendliness, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred. <Resin layer containing polyvinyl alcohol-based resin>

[0028] The resin layer 3 containing a polyvinyl alcohol-based resin is provided on the surface of the anchor coat layer 2 opposite the paper substrate 1, and is provided to improve adhesion between the anchor coat layer 2 and the vapor-deposited layer 4. Examples of polyvinyl alcohol-based resins include fully saponified polyvinyl alcohol resins, partially saponified polyvinyl alcohol resins, modified polyvinyl alcohol resins, and ethylene-vinyl alcohol copolymer resins. The degree of polymerization of the polyvinyl alcohol-based resin is preferably 300 or more and 1500 or less. A degree of polymerization of 300 or more improves the barrier properties and flex resistance of the moisture-proof layer, while a degree of polymerization of 1500 or less reduces the viscosity of the coating liquid of the polyvinyl alcohol-based resin described below, improving coatability.

[0029] The resin layer 3 can be provided by applying a coating liquid containing the polyvinyl alcohol resin and a solvent to the surface of the anchor coat layer 2 opposite the paper substrate 1, followed by drying. Examples of solvents contained in the coating liquid include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, and dimethylacetamide. Mixtures of water and alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol are particularly preferred. The coating liquid may also contain additives such as surfactants, preservatives, storage stabilizers, silane coupling agents, and organic titanates.

[0030] Such a resin layer 3 has excellent flexibility, can suppress cracking of the vapor-deposited layer 4, and can improve the adhesion between the vapor-deposited layer 4 and the resin layer 3.

[0031] The thickness of the resin layer 3 may be, for example, 1 μm or more, and preferably 2 μm or more and 5 μm or less. If the thickness of the resin layer 3 is 1 μm or more, the vapor-deposited layer 4 can be laminated uniformly. Furthermore, even if the thickness of the resin layer 3 is greater than 5 μm, there is no problem in terms of moisture resistance, but if the thickness of the resin layer 3 is 5 μm or less, the vapor-deposited layer 4 can be laminated uniformly while keeping costs down. <Vapour-deposited layer>

[0032] The vapor-deposited layer 4 is a layer obtained by vapor-depositing a metal or an inorganic compound. The vapor-deposited layer 4 may be obtained by vapor-depositing aluminum, or may contain aluminum oxide (AlOx), silicon oxide (SiOx), or the like.

[0033] The thickness of the vapor-deposited layer 4 may be set appropriately depending on the intended use, but may be 30 nm to 100 nm, and preferably 50 nm to 80 nm. A thickness of 30 nm or more makes it easier to ensure sufficient continuity of the vapor-deposited layer 4, while a thickness of 100 nm or less makes it easier to suppress the occurrence of curling and cracking and to achieve sufficient moisture-proof performance.

[0034] From the viewpoint of film uniformity, it is preferable to form the vapor deposition layer 4 by a vacuum deposition method. While known deposition methods include vacuum evaporation, sputtering, and chemical vapor deposition (CVD), vacuum deposition is preferred due to its high deposition rate and high productivity. Among vacuum deposition methods, electron beam heating is particularly effective because it allows the deposition rate to be easily controlled by the irradiation area and electron beam current, and the temperature of the deposition material can be increased or decreased in a short time. <Overcoat layer>

[0035] The overcoat layer 5 is provided on the surface of the vapor-deposited layer 4 opposite the resin layer 3 so as to be in contact with the vapor-deposited layer 4, and contains a second polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

[0036] Such an overcoat layer 5 has excellent flexibility, can suppress cracking of the vapor-deposited layer 4, and has excellent adhesion to the vapor-deposited layer 4. Furthermore, by including the second polyolefin described above, a laminate with excellent water vapor barrier properties can be obtained.

[0037] The overcoat layer 5 may contain other components in addition to the second polyolefin, such as a silane coupling agent, organic titanate, polyacrylic, polyester, polyurethane, polycarbonate, polyurea, polyamide, polyolefin emulsion, polyimide, melamine, and phenol.

[0038] The content of the second polyolefin in the overcoat layer 5 may be, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass.

[0039] The thickness of the overcoat layer 5 may be, for example, 2 μm or more, and preferably 3 μm or more. The thickness of the overcoat layer 5 may be 10 μm or less, and is preferably 8 μm or less, and more preferably 5 μm or less. Although there is no problem with moisture resistance even if the thickness of the overcoat layer 5 is greater than 10 μm, if the thickness of the overcoat layer 5 is 10 μm or less, it is possible to suppress costs and to sufficiently exhibit adhesion to the vapor deposition layer 4 and barrier properties.

[0040] The overcoat layer 5 can be provided by applying a coating liquid containing the polyolefin and a solvent to the surface of the vapor-deposited layer 4 opposite the resin layer 3, followed by drying. Examples of solvents contained in the coating liquid include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used alone or in combination. Among these, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred from the viewpoint of properties. Furthermore, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred from the viewpoint of environmental friendliness.

[0041] The first polyolefin and the second polyolefin contained in the anchor coat layer 2 and the overcoat layer 5, respectively, may be the same or different, but considering ease of production, it is preferable that they are the same. <Adhesive primer layer>

[0042] The adhesive primer layer 6 is provided to ensure sufficient adhesion with various laminating adhesives, such as isocyanate-curing urethane resins and modified vinyl acetate resin emulsions, used when laminating onto the surface of various substrates. Known primer materials include ester resins, urethane resins, acrylic resins, polycarbonate resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral resins, and nitrocellulose resins. A primer suitable for the type of laminating adhesive is selected from these. For example, when using a modified vinyl acetate resin emulsion adhesive as the laminating adhesive, good adhesion can be achieved by providing an adhesive primer layer 6 made of a urethane adhesive primer.

[0043] If an inorganic fine powder such as silica is added to the adhesive primer, the surface of the adhesive primer layer 6 is roughened, which not only prevents blocking when the moisture-proof sheet is rolled up and stored, but also improves adhesion to the laminating adhesive due to its anchoring effect. The adhesive primer layer 6 can be formed by using an adhesive composition, either alone or in combination, and then applying it by a suitable coating method such as roll coating or gravure printing.

[0044] While one embodiment of the moisture-proof backside paper 10 for decorative laminates according to this embodiment has been described above, the present invention may also include other layers. For example, in FIG. 1 , the resin layer 3 containing a polyvinyl alcohol resin is disposed between the anchor coat layer 2 and the vapor-deposited layer 4, but it may also be disposed between the paper substrate 1 and the anchor coat layer 2. That is, the resin layer 3 may be disposed between the paper substrate 1 and the anchor coat layer 2, or between the anchor coat layer 2 and the vapor-deposited layer 4. By providing the resin layer 3 between the anchor coat layer 2 and the vapor-deposited layer 4, the adhesion between the anchor coat layer 2 and the vapor-deposited layer 4 can be improved, and by providing the resin layer 3 between the paper substrate 1 and the anchor coat layer 2, the adhesion between the paper substrate 1 and the anchor coat layer 2 can be improved. <Effects>

[0045] The moisture-proof backside paper for decorative panels according to the present invention has a lower moisture permeability (JIS Z 0208) than conventional moisture-proof sheets made of synthetic resins such as vinyl chloride, polyethylene, or polypropylene, or made of paper / polyethylene / paper. 2 Therefore, it is possible to obtain a moisture-proof paper for the back side of decorative laminates that has excellent moisture-proofing properties and can prevent warping even when used in places where there is a large difference in temperature and humidity between the two sides. The moisture permeability is 0g / m 2 ·5.0g / m over 24hr 2 24 hours or less is preferable, 0.1 g / m 2 ·4.0g / m over 24hr 2 24 hours or less is more preferable, and 0.5 g / m 2 ·3.0g / m over 24hr 2 24 hours or less is preferable.

[0046] Furthermore, because this moisture-proof paper for the back side of decorative panels uses a paper base material 1, the amount of plastic material used can be reduced compared to moisture-proof paper that uses conventional plastic materials, making it possible to realize a moisture-proof paper for the back side of decorative panels that has higher moisture permeability than conventional papers and allows for a reduction in the amount of plastic material used. [Example]

[0047] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples in any way. Example 1

[0048] Paper base material: 50g / m 2 A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals, Inc.) was applied to the surface of the paper using a bar coater and dried in an oven to form an anchor coat layer. The thickness of the anchor coat layer was 3 μm.

[0049] Next, a coating solution containing polyvinyl alcohol resin (a polyvinyl alcohol resin with a saponification degree of 98% and a polymerization degree of 500 dissolved in a water / IPA solution at a solids concentration of 10% by mass) was applied onto the anchor coat layer using a bar coater and dried in an oven to form a resin layer containing polyvinyl alcohol resin. The thickness of the resin layer containing polyvinyl alcohol resin was 1 μm.

[0050] Next, aluminum was vapor-deposited onto the resin layer containing polyvinyl alcohol resin. The thickness of the aluminum vapor-deposited layer was 50 nm. A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals, Inc.) was then applied onto the vapor-deposited layer using a bar coater and dried in an oven to form an overcoat layer, resulting in a moisture-proof layer. The thickness of the polyolefin-containing overcoat layer was 3 μm. This resulted in a moisture-proof paper for the back side of decorative laminates, with a moisture-proof layer laminated on top of the paper substrate. Example 2 A moisture-proof backside paper for decorative boards was obtained in the same manner as in Example 1, except that the thickness of the anchor coat layer was set to 5 μm. Example 3 A moisture-proof backside paper for decorative boards was obtained in the same manner as in Example 1, except that the thickness of the overcoat layer was 2 μm. Example 4 A moisture-proof backside paper for decorative boards was obtained in the same manner as in Example 1, except that the thickness of the overcoat layer was 10 μm. Example 5 A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 1, except that the thickness of the vapor-deposited layer was 30 nm. Example 6 A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 1, except that the thickness of the vapor-deposited layer was 100 nm. Example 7 A moisture-proof backside paper for decorative boards was obtained in the same manner as in Example 1, except that the thickness of the anchor coat layer was 1 μm and the thickness of the resin layer containing polyvinyl alcohol resin was 5 μm. Example 8 A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 1, except that silica was used for the vapor-deposited layer and the thickness of the vapor-deposited layer was 30 nm. Example 9 A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 1, except that alumina was used for the vapor-deposited layer, and the thickness of the vapor-deposited layer was set to 30 nm. Example 10 Paper base material: 50g / m 2 A coating solution containing polyvinyl alcohol resin, prepared by dissolving polyvinyl alcohol resin with a saponification degree of 98% and a degree of polymerization of 500 in a water / IPA solution at a solids concentration of 10% by mass, was applied to the surface of the paper using a bar coater, and the paper was dried in an oven to form a resin layer containing polyvinyl alcohol resin. The thickness of the resin layer containing polyvinyl alcohol resin was 1 μm. Next, a coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals, Inc.) was applied onto the resin layer containing polyvinyl alcohol resin using a bar coater and dried in an oven to form an anchor coat layer with a thickness of 3 μm. Next, aluminum was vapor-deposited onto the anchor coat layer. The thickness of the aluminum vapor-deposited layer was 50 nm. A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals, Inc.) was then applied onto the vapor-deposited layer using a bar coater and dried in an oven to form an overcoat layer, resulting in a moisture-proof layer. The polyolefin-containing overcoat layer had a thickness of 3 μm. This resulted in a moisture-proof paper for decorative laminates with a back surface, consisting of a moisture-proof layer laminated on a paper substrate. Example 11 A moisture-proof backside paper for decorative boards was obtained in the same manner as in Example 10, except that the thickness of the anchor coat layer was set to 5 μm. Example 12 A moisture-proof backside paper for decorative boards was obtained in the same manner as in Example 10, except that the thickness of the overcoat layer was 2 μm. Example 13 A moisture-proof backside paper for decorative boards was obtained in the same manner as in Example 10, except that the thickness of the overcoat layer was 10 μm. Example 14 A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 10, except that the thickness of the vapor-deposited layer was 30 nm. Example 15 A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 10, except that the thickness of the vapor-deposited layer was 100 nm. Example 16 A moisture-proof backside paper for decorative boards was obtained in the same manner as in Example 10, except that the thickness of the resin layer containing polyvinyl alcohol resin was 5 μm and the thickness of the anchor coat layer was 1 μm. Example 17 A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 10, except that silica was used for the vapor-deposited layer and the thickness of the vapor-deposited layer was 30 nm. Example 18 A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 10, except that alumina was used for the vapor-deposited layer, and the thickness of the vapor-deposited layer was set to 30 nm. (Comparative Example 1)

[0051] A moisture-proof backside paper for decorative sheets was obtained in the same manner as in Example 1, except that no vapor deposition layer was provided. (Comparative Example 2)

[0052] 50g / m as paper base material 2 A coating solution containing a vinyl acetate-based polyolefin resin was applied to the surface of the reinforced paper (manufactured by Tenma Tokushu Paper Co., Ltd.) using a bar coater and dried in an oven to form a layer containing a vinyl acetate-based polyolefin resin. The thickness of the vinyl acetate-based polyolefin resin layer was 3 μm. Subsequently, aluminum was vapor-deposited on the layer containing the vinyl acetate-based polyolefin resin. The thickness of the vapor-deposited aluminum layer was 50 nm. A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals, Inc.) was then applied to the vapor-deposited layer using a bar coater and dried in an oven to form a layer containing polyolefin, thus obtaining a moisture-proof layer. The thickness of the polyolefin-containing layer was 3 μm. This resulted in a backside moisture-proof paper for decorative laminates, in which a moisture-proof layer was laminated on a paper substrate. (Comparative Example 3)

[0053] As a conventional moisture-proof sheet, a 30g / m2 sheet with corona treatment on one side was used. 2 The corona-treated surfaces of the above-mentioned reinforced inter-paper sheets (manufactured by Tenma Special Paper Co., Ltd.) were sandwich-laminated with 50 μm of molten polyethylene resin extruded from a T-die extruder to produce a moisture-proof sheet (reinforced inter-paper sheets / polyethylene / reinforced inter-paper sheets). <Evaluation>

[0054] The moisture permeability of the moisture-proof backside paper and moisture-proof sheets for decorative boards of the Examples and Comparative Examples prepared above was calculated in accordance with JIS Z 0208. The results are shown in Tables 1 to 3.

[0055] Furthermore, the film uniformity of the vapor-deposited layer 4 was evaluated for the moisture-proof backside paper and moisture-proof sheet for decorative backing boards of the above Examples and Comparative Examples. This evaluation was made indirectly based on the moisture permeability. 2 If the moisture permeability is less than 24 hours, it is marked as "○" and if the moisture permeability is 4g / m 2 The results are shown in Tables 1 to 3. [Table 1] [Table 2] [Table 3]

[0056] As such, from Tables 1 to 3, it was possible to verify that it is possible to provide a moisture-proof paper for the back side of decorative panels that can prevent warping even when used in places where there is a large difference in temperature and humidity environment on both sides, which is the objective of the present invention. [Explanation of symbols]

[0057] 1...Paper base material 2. Anchor coat layer 3. Resin layer containing polyvinyl alcohol resin 4... Vapor deposition layer 5. Overcoat layer 6. Adhesion primer layer 10. Moisture-proof paper backing for decorative panels 20. Moisture barrier

Claims

1. A back moisture-proof paper for decorative panels in which a paper substrate and a moisture-proof layer are laminated, the moisture-proof layer is formed by laminating an anchor coat layer, a vapor deposition layer, and an overcoat layer in this order from the paper substrate side; the anchor coat layer includes a first polyolefin having a salt of a carboxyl group, the overcoat layer comprises a second polyolefin having a salt of a carboxyl group; Furthermore, the moisture-proof backside paper for decorative panels is characterized in that it has a resin layer containing a polyvinyl alcohol-based resin between the paper base material and the anchor coat layer or between the anchor coat layer and the vapor deposition layer.

2. 2. The moisture-proof backside paper for decorative sheets according to claim 1, wherein the thickness of the anchor coat layer is 1 μm or more.

3. 3. The moisture-proof backside paper for decorative sheets according to claim 1, wherein the resin layer containing the polyvinyl alcohol-based resin has a thickness of 1 μm or more.

4. 4. The moisture-proof backside paper for decorative sheets according to claim 1, wherein the thickness of the vapor-deposited layer is 30 nm or more and 100 nm or less.

5. 5. The moisture-proof backside paper for decorative sheets according to claim 1, wherein the thickness of the overcoat layer is 2 μm or more.

6. 6. The moisture-proof backside paper for decorative panels according to claim 1, wherein the weight of the paper substrate is 50% by mass or more of the weight of the entire moisture-proof layer.

7. The moisture-proof backside paper for decorative panels according to any one of claims 1 to 6, characterized in that the paper base material is a thin paper that is reinforced between the sheets by mixing a synthetic resin into the thin paper to strengthen the strength between the sheets.

8. A moisture-proof paper for decorative panels having a back surface described in any one of claims 1 to 7, characterized in that the first polyolefin and the second polyolefin are water-dispersible polyolefins.

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