Gypsum board, interior material, and method for manufacturing gypsum board

Abstract

A gypsum board includes: a gypsum core; a gypsum core; a board liner paper sheet arranged on each of a first main surface of the gypsum core and a second main surface of the gypsum core located opposite to the first main surface; and a coating layer disposed on a surface of the board liner paper sheet located on the first main surface of the gypsum core, the surface being a surface of the board liner paper sheet opposite to the surface of the board liner paper sheet facing the gypsum core. The gypsum core includes an anti-mold agent having a solubility in water of 100 ppm or more, and content of a waterproofing agent in the gypsum core is less than 0.1 parts by mass per 100 parts by mass of gypsum.

Description

DESCRIPTION TITLE OF THE INVENTION: GYPSUM BOARD, INTERIOR MATERIAL, AND METHOD FOR MANUFACTURING GYPSUM BOARD TECHNICAL FIELD

[0001] The present invention relates to gypsum board, interior material, and method for manufacturing gypsum board. BACKGROUND ART

[0002] Patent Document 1 discloses a gypsum material having antibacterial and anti-mold properties, wherein a soluble glass capable of eluting silver or copper ions is mixed with gypsum in the form of powder, beads, or fibers. RELATED ART DOCUMENTS PATENT DOCUMENTS

[0003] Patent Document 1: Japanese Laid-Open Patent Application No. H2-302354 SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0004] Conventionally, gypsum boards have been used for interior wall and ceiling materials.

[0005] In the gypsum boards used for wall and ceiling materials, a temperature difference may occur between the front surface located on an indoor side and the back surface located opposite to the front surface. As a result, dew condensation may occur on the front and back surfaces of the gypsum boards depending on humidity or the like of the environment where the gypsum boards are installed, and mold may occur on the gypsum boards.

[0006] When mold is generated on the gypsum board, it may be necessary to replace the gypsum board from the viewpoint of appearance and hygiene depending on the degree of mold. Therefore, for the purpose of suppressing the generation of mold on the gypsum board, a gypsum board in which a material capable of imparting an anti- mold performance to the gypsum board is added to a gypsum core or the like as disclosed in Patent Document 1 or the like has been conventionally studied.

[0007] Therefore, a gypsum board having excellent anti-mold performance has been considered necessary.

[0008] Therefore, one object is to provide a gypsum board having excellent anti-mold performance. MEANS FOR SOLVING THE PROBLEMS

[0009] According to an aspect of the present invention, provided is a gypsum board including: a gypsum core; a board liner paper sheet arranged on each of a first main surface of the gypsum core and a second main surface of the gypsum core located opposite to the first main surface; and a coating layer disposed on a surface of the board liner paper sheet located on the first main surface of the gypsum core, the surface being a surface of the board liner paper sheet opposite to the surface facing the gypsum core, wherein the gypsum core includes an anti-mold agent having a solubility in water of 100 ppm or more, and content of a waterproofing agent in the gypsum core is less than 0.1 parts by mass per 100 parts by mass of gypsum. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0010] According to one aspect of the present invention, a gypsum board having excellent anti-mold performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] [FIG. 1] FIG. 1 is a perspective view of a gypsum board according to one aspect of the present disclosure. [FIG. 2] FIG. 2 is a cross-sectional view of the gypsum board according to one aspect of the present disclosure. [FIG. 3] FIG. 3 is a cross-sectional view showing a case where a gypsum core of the gypsum board includes recesses. [FIG. 4] FIG. 4 is an explanatory view of an interior material according to one aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiments of the present invention will be described in the following with reference to the drawings, but the present invention is not limited to the following embodiments, and various modifications and substitutions may be made to the following embodiments without departing from the scope of the present invention. [Gypsum board] Hereinafter, a gypsum board according to one embodiment (hereinafter referred to as "embodiment") of the present disclosure will be described with reference to the drawings.

[0013] Each of the drawings is a schematic view for explaining the structure of the gypsum board or the like of the present embodiment, and does not accurately describe the size or the like.

[0014] FIG. 1 is a perspective view of the gypsum board according to the present embodiment, and FIGS. 2 and 3 are cross- sectional views of the gypsum board according to the present embodiment. FIG. 3 is an explanatory view in the case where a gypsum core of the gypsum board according to the present embodiment includes recesses on the first main surface. Therefore, the gypsum board according to the present embodiment will be described mainly with reference to FIGS. 1 and 2, and FIG. 3 will be used as necessary. In FIGS. 1, 2, and 3, the Z-axis is an axis along the thickness of the gypsum board, as well as an axis along the lamination direction of the gypsum core, the board liner paper sheet, and the coating layer. The XY plane is a plane perpendicular to the Z-axis. (1) Structure of the gypsum board As shown in FIGS. 1 and 2, a gypsum board 10 of the present embodiment includes a gypsum core 11, a board liner paper sheet 12, and a coating layer 13. (Gypsum core) The gypsum core 11 is a hardened body of gypsum slurry, as will be described in the following in the manufacturing method of the gypsum board. The gypsum core 11 can include gypsum, specifically gypsum dihydrate, various additives, and an anti-mold agent. Various additives which can be contained in the gypsum core 11 will be described with reference to the manufacturing method of the gypsum board. The anti- mold agent will be described in the following.

[0015] As shown in FIG. 3, a first main surface 11A of the gypsum core 11 of the gypsum board 10 of the present embodiment may include recesses 31. When the gypsum board 10 of the present embodiment is used as an interior material such as a wall material or a ceiling material, the first main surface 11A is a surface located on the indoor side, and a screw or the like is struck through the surface in order to fix the gypsum board to a base. Therefore, since the first main surface 11A of the gypsum core 11 includes the recesses 31, a travertine pattern or a marble-like pattern can be formed on the first main surface 11A of the gypsum board 10. As a result, a screw or the like struck on the first main surface 11A of the gypsum board 10 becomes less conspicuous, and the design property is enhanced. (Board liner paper sheet) The board liner paper sheet 12 can be arranged on the first main surface 11A and on a second main surface 11B located opposite to the first main surface 11A of the gypsum core 11. The board liner paper sheet 12 arranged on the first main surface 11A may be referred to as a first board liner paper sheet 121, and the board liner paper sheet 12 arranged on the second main surface 11B may be referred to as a second board liner paper sheet 122 or the like. In FIG. 1, the first board liner paper sheet 121 and the second board liner paper sheet 122 are described as separate members that are not connected to each other, but the embodiment is not limited thereto. The first board liner paper sheet 121 and the second board liner paper sheet 122 may be one continuous board liner paper sheet that is arranged to cover a side surface 11C of the gypsum core 11 (see FIG. 2) or the like, or two or more board liner paper sheets may be bonded together with glue or the like to form an integrated liner paper sheet. In addition, as shown in FIGS. 1 and 2, the first board liner paper sheet 121 and the second board liner paper sheet 122 may be separate members that are not connected to each other.

[0016] The first main surface 11A and the second main surface 11B are surfaces that cross the thickness direction of the gypsum board 10. The first main surface 11A and the second main surface 11B are surfaces that serves as a wall surface or a ceiling surface when the gypsum board 10 is used as an interior material such as a wall material or a ceiling material.

[0017] The gypsum core 11 may also include the recesses 31 in the first main surface 11A as described above. When the gypsum core 11 includes the recesses 31 in the first main surface 11A, it is preferable that the board liner paper sheet 12 is also disposed on a bottom surface 31A and side surfaces 31B of each recess 31 of the gypsum core 11 as shown in FIG. 3. That is, when the gypsum core 11 includes the recesses 31, it is preferable that the board liner paper sheet 12 also includes recesses at positions corresponding to the recesses 31 of the gypsum core 11.

[0018] The board liner paper sheet 12 is not particularly limited, and various types of board liner paper sheet that are used for gypsum board, for example, can be used. (Coating layer) The coating layer 13 can be disposed on the board liner paper sheet 12 positioned on the first main surface 11A of the gypsum core 11, that is, on a first surface 121A of the first board liner paper sheet 121, which is a surface opposite to a second surface 121B that faces the gypsum core 11.

[0019] The coating layer 13 may cover the entire first surface 121A of the first board liner paper sheet 121, or may cover only a part of the first surface 121A.

[0020] Note that the coating layer is not provided on the second board liner paper sheet 122 positioned on the second main surface 11B of the gypsum core 11, and the second board liner paper sheet 122 can be configured to include a back surface 10B that is the outer surface of the gypsum board 10.

[0021] Since the gypsum board 10 of the present embodiment includes the coating layer 13, it is considered that it is possible to prevent the anti-mold agent contained in the gypsum core 11 from flowing out to the outside and to increase the concentration of the anti- mold agent in the vicinity of a front surface 10A of the gypsum board 10. Therefore, when the gypsum board 10 includes the coating layer 13, it is considered that the anti-mold performance of the gypsum board 10 can be enhanced.

[0022] The coating layer 13 may contain an anti-mold agent. That is, in the gypsum board 10 of the present embodiment, the gypsum core 11, and the coating layer 13 may each contain an anti-mold agent.

[0023] The coating layer 13 can be formed, for example, by applying paint to the first surface 121A of the first board liner paper sheet 121, and when the coating layer 13 is to contain an anti-mold agent, the paint applied may include the anti-mold agent.

[0024] The paint used for forming the coating layer 13 may also contain a resin. The resin may fix the anti-mold agent to the first surface 121A of the first board liner paper sheet 121 when the paint contains the anti-mold agent.

[0025] That is, the coating layer 13 may include a resin. As the resin contained in the coating layer 13, for example, one or more kinds selected from a group including an acrylic resin, an acrylamide resin, a urethane resin, a silicon resin, an epoxy resin, and the like may be used.

[0026] As described above, the gypsum core 11 may include the recesses 31 on the first main surface 11A. When the gypsum core 11 includes the recesses 31 on the first main surface 11A, the coating layer 13 may or may not be disposed on the surfaces of the bottom surface 31A and the side surfaces 31B of the recesses 31. For example, as shown in FIG. 3, the coating layer 13 may be provided only on the surfaces of projections 32 disposed between the recesses 31 of the gypsum core 11. In this case, the board liner paper sheet 12 is disposed on the surfaces of the bottom surface 31A and the side surfaces 31B of the recesses 31.

[0027] A thickness T13 of the coating layer 13 is not particularly limited, but the average value of the thickness T13 of the coating layer 13 may be, for example, within a range from 0.01 mm to 0.3 mm.

[0028] When the average value of the thickness of the coating layer 13 is 0.01 mm or more, the strength of the coating layer 13 can be sufficiently enhanced. When the coating layer 13 contains an anti-mold agent, when the average value of the thickness of the coating layer 13 is 0.01 mm or more, the coating layer 13 can contain a sufficient amount of the anti-mold agent, and the anti-mold performance of the gypsum board 10 can be particularly enhanced.

[0029] When the average value of the thickness of the coating layer 13 is 0.3 mm or less, the formation of the coating layer 13 can be facilitated, and the productivity of the gypsum board can be enhanced.

[0030] The average value of the thickness of the coating layer 13 can be obtained by the following procedure.

[0031] The thickness of the gypsum board before the formation of the coating layer 13 and the thickness of the gypsum board after the formation of the coating layer 13 can be measured for each gypsum board according to the thickness measurement method specified in Japanese Industrial Standards (JIS) A 6901:2014, "Gypsum board products". Specifically, the thickness of each gypsum board can be obtained by measuring the thickness of the gypsum board at six locations within 25 mm from end surfaces and 80 mm or more from both side surfaces of the sample to be measured at equal intervals, and obtaining the average value of the measured values. When the width of the region to be evaluated is 606 mm or less, the thickness can be measured at three locations.

[0032] Then, by using the obtained thicknesses of the gypsum board before and after the formation of the coating layer 13, the thickness of the coating layer, that is, the average value of the thickness of the coating layer can be calculated by using the following equation:

[0033] (thickness of the coating layer) = (thickness of the gypsum board after the formation of the coating layer) - (thickness of the gypsum board before the formation of the coating layer) When the coating layer has already been formed, the gypsum board after the removal of the coating layer may be used for evaluation as the gypsum board before the formation of the coating layer. In addition, gypsum boards before and after the formation of the coating layer may be manufactured by using another material and used for evaluation. (2) Anti-mold agent Inventors of the present invention examined the gypsum boards having excellent anti-mold performance.

[0034] From the viewpoint of enhancing the anti-mold performance of the gypsum board 10, the anti-mold agent can be added to the gypsum board 10. When adding an anti-mold agent to the gypsum board 10, it is considered that the anti-mold agent is added to the gypsum core 11. However, among the anti-mold agent added to the gypsum core 11, it is mainly the anti-mold agent located on the front surface 10A of the gypsum board 10 or in the vicinity thereof that contributes to the effect of enhancing the anti-mold performance of the gypsum board. Therefore, when the anti-mold agent is added to the gypsum core 11, since a large amount of the anti-mold agent is contained in the gypsum core 11, there is an issue that the ratio of the anti-mold agent that does not contribute to the enhancement of the anti-mold performance increases.

[0035] Therefore, the inventors of the present invention further investigated the issue. As a result, the gypsum core 11 of the gypsum board 10 of the present embodiment can contain the anti-mold agent. The gypsum core 11 can contain the anti-mold agent having a solubility in water of 100 ppm or more. According to the investigation by the inventors of the present invention, the anti-mold performance of the gypsum board 10 can be enhanced by adopting the above configuration.

[0036] Since the gypsum core 11 contains the anti-mold agent having a solubility in water of 100 ppm or more, that is, the water- soluble anti-mold agent, the anti-mold agent can be dissolved in the moisture of the gypsum slurry used for manufacturing the gypsum core 11. When the gypsum core 11 is manufactured, the anti-mold agent in the gypsum slurry is sucked into the board liner paper sheet 12 in the process of arranging and molding the gypsum slurry between the board liner paper sheets, and the concentration of the anti-mold agent in the board liner paper sheet 12 is increased. Therefore, the anti-mold performance on the front surface 10A or the like of the gypsum board 10 can be sufficiently enhanced without directly adding the anti-mold agent to the board liner paper sheet 12 by including the anti-mold agent having a solubility in water of 100 ppm or more in the gypsum core 11.

[0037] The amount of the anti-mold agent included in the gypsum core 11 is not particularly limited and can be selected according to the required anti-mold performance or the like. For example, when all the gypsum included in the gypsum core is assumed to be gypsum dihydrate, the anti-mold agent is preferably included in a mass ratio of within a range from 50 ppm to 1,000 ppm, and more preferably in a mass ratio of within a range from 100 ppm to 500 ppm relative to the gypsum dihydrate.

[0038] By including the anti-mold agent in a mass ratio of 50 ppm or more relative to the gypsum dihydrate in the gypsum core 11, gypsum board having particularly excellent anti-mold performance can be obtained.

[0039] As the amount of the anti-mold agent included in the gypsum core 11 increases, the anti-mold performance tends to increase. However, the anti-mold agent is preferably included in the gypsum core 11 in a mass ratio of 1,000 ppm or less relative to the gypsum dihydrate, because even when the anti-mold agent is included in a mass ratio of more than 1,000 ppm relative to the gypsum dihydrate, excessive anti-mold performance and high cost result.

[0040] When the gypsum board including the recesses 31 on the front surface 10A is formed by embossing as shown in FIG. 3, there are instances where the coating layer 13 is not provided on the surface of the first board liner paper sheet 121 on the bottom surfaces 31A and the side surfaces 31B of the recesses 31. In the gypsum board including the recesses 31, when the coating layer 13 is not provided on the surface of the first board liner paper sheet 121 on the bottom surface 31A and the side surfaces 31B of the recesses 31, the first board liner paper sheet 121 is exposed on the bottom surface 31A and the side surfaces 31B of the recesses 31. Therefore, by enhancing the anti-mold performance on the front surface 10A of the gypsum board 10, especially on the surface of the first board liner paper sheet 121, it is also possible to prevent the generation of mold at places where the coating layer 13 is not provided, such as the bottom surfaces 31A and the side surfaces 31B of the recesses 31.

[0041] In addition, for example, when the gypsum board 10 is used for a ceiling board, when condensation water is generated on the back surface 10B of the gypsum board 10, the condensation water permeates into the front surface 10A from the back surface 10B of the gypsum board 10. When the condensation water permeates into the gypsum board 10, the anti-mold agent in the gypsum core is dissolved in the condensation water and moves toward the front surface 10A, and the concentration of the anti-mold agent on the front surface 10A and its vicinity is further increased. Therefore, the anti-mold performance on the front surface 10A of the gypsum board 10 can be enhanced. In addition, even when the gypsum board includes the recesses 31 on the front surface 10A and no coating layer 13 is provided on the bottom surfaces 31A and the side surfaces 31B of the recesses 31, the anti-mold performance on the bottom surface 31A and the side surfaces 31B of the recesses 31 can be further enhanced by the permeation of the condensation water into the gypsum board 10.

[0042] Incidentally, as described above, the coating layer 13 may also contain an anti-mold agent. By arranging the anti-mold agent also in the coating layer 13, it is possible to particularly suppress the generation of mold on the front surface 10A of the gypsum board 10.

[0043] The amount of the anti-mold agent contained in the coating layer 13 is not particularly limited and can be selected in accordance with required anti-mold performance and the like. For example, when it is assumed that the gypsum contained in the gypsum core 11 is only gypsum dihydrate, the anti-mold agent contained in the coating layer 13 is preferably contained in a mass ratio of within a range from 10 ppm to 1,000 ppm, and more preferably in a mass ratio of within a range from 20 ppm to 500 ppm, relative to the gypsum dihydrate contained in the gypsum core.

[0044] When the coating layer 13 contains the anti-mold agent in a mass ratio of 10 ppm or more relative to the gypsum dihydrate contained in the gypsum core 11, gypsum board having particularly excellent anti-mold performance can be obtained.

[0045] As the amount of the anti-mold agent contained in the coating layer 13 increases, the anti-mold performance tends to increase. However, even when the anti-mold agent is contained in a mass ratio of more than 1,000 ppm relative to the gypsum dihydrate contained in the gypsum core 11, the anti-mold performance is excessive and the cost is high. For this reason, it is preferable that the coating layer 13 contains an anti-mold agent at a mass ratio of 1,000 ppm or less relative to the gypsum dihydrate contained in the gypsum core 11.

[0046] Since the gypsum core 11 may contain a plurality of kinds of anti-mold agents, the gypsum core 11 may contain an anti-mold agent having a solubility in water of less than 100 ppm in addition to an anti-mold agent having a solubility in water of 100 ppm or more, for example.

[0047] When the coating layer 13 contains an anti-mold agent, the anti-mold agent contained in the coating layer 13 is not particularly limited and may contain an anti-mold agent having a solubility in water of 100 ppm or more or an anti-mold agent having a solubility in water of less than 100 ppm in the same manner as the gypsum core 11. The coating layer 13 may also contain a plurality of kinds of anti-mold agents.

[0048] Therefore, the anti-mold agent contained in the coating layer 13 may be one or more kinds selected from a group including an anti-mold agent having a solubility in water of 100 ppm or more and an anti-mold agent having a solubility in water of less than 100 ppm, for example.

[0049] The anti-mold agent contained in the gypsum core 11 and the coating layer 13 may be different or the same. Furthermore, the gypsum core 11 and the coating layer 13 may each contain only one kind of anti-mold agent, and either or both of the gypsum core 11 and the coating layer 13 may contain two or more kinds of anti-mold agents.

[0050] Therefore, for example, the gypsum core 11 may contain at least one kind of anti-mold agent different from the anti-mold agent contained in the coating layer 13.

[0051] The anti-mold agent added to the gypsum core 11 and the coating layer 13 is mainly disposed near the front surface 10A of the gypsum board 10, thereby contributing to enhancement of anti-mold performance on the front surface 10A of the gypsum board 10. However, since materials disposed around the anti-mold agent differ between the coating layer 13 and the gypsum core 11, the preferred anti-mold agent may also differ.

[0052] Therefore, when the gypsum core 11 contains at least one kind of anti-mold agent different from the anti-mold agent contained in the coating layer 13, the anti-mold agent contained in the gypsum core 11 and the coating layer 13 positioned on the front surface 10A of the gypsum board 10 can be especially optimized. Therefore, anti-mold performance of the gypsum board 10 can be enhanced.

[0053] Since the gypsum core 11 contains the anti-mold agent having a solubility in water of 100 ppm or more, the amount of the anti- mold agent dissolved in the gypsum slurry can be increased at the time of manufacturing the gypsum core 11, and the anti-mold agent can be particularly readily contained in the board liner paper sheet 12.

[0054] The coating layer 13 can also contain the anti-mold agent having a solubility in water of less than 100 ppm, for example, as described above. Since the coating layer 13 contains the anti-mold agent having a solubility in water of less than 100 ppm, the elution of the anti-mold agent from the coating layer 13 to the board liner paper sheet 12 can be suppressed, and the amount of the anti-mold agent contained in the coating layer 13 can be particularly increased. Therefore, the anti-mold agent located on the front surface 10A of the gypsum board 10 can be particularly increased, and the anti-mold performance of the gypsum board 10 can be particularly enhanced.

[0055] The solubility of the anti-mold agent in water can be evaluated, for example, by the following procedure.

[0056] For example, the anti-mold agent is added to water at 25°C, stirred for not less than 10 minutes and not more than 20 minutes, and then the undissolved anti-mold agent is removed by solid- liquid separation, and only the liquid portion is collected. Then, the concentration of the anti-mold agent in the mass ratio contained in the liquid portion can be evaluated and defined as the solubility of the anti- mold agent in water. As the water, water from which impurities have been sufficiently removed, for example, distilled water, can be used. The concentration of the anti-mold agent contained in the liquid portion can be evaluated by liquid chromatography or the like.

[0057] Examples of the anti-mold agent that can be used for the gypsum board of the present embodiment include one or more kinds selected from a group including 3-ido-2-propyl butyl carbamate (IPBC, solubility: 156 ppm), imazalil (IMZ, solubility: 180 ppm), 2-N-octyl-4- isothiazolin-3-one (OIT, solubility: 480 ppm), 2-benzimidazol carbamic acid methyl ester (BCM, solubility: 5.6 ppm), orthophenylphenol (OPP, solubility: 700 ppm), 2-(4-thiazolyl)-benzimidazole (TBZ, solubility: 30 ppm), (solubility: 15 ppm), zinc pyrithione (ZPT, solubility: 15 ppm), fludioxonil (FDO, solubility: 1.8 ppm) and the like. It should be noted that each of the above solubility means solubility in water. (3) Waterproofing agent The content of the waterproofing agent in the gypsum core 11 of the gypsum board 10 of the present embodiment can be less than 0.1 parts by mass based on 100 parts by mass of gypsum. The gypsum core 11 of the present embodiment need not contain the waterproofing agent. The content of the waterproofing agent means the ratio of the waterproofing agent to 100 parts by mass of gypsum dihydrate when the gypsum contained in the gypsum core is regarded as the gypsum dihydrate.

[0058] As described above, for example, when the gypsum board 10 is used for a ceiling board, there is a case where dew condensation water is generated on the back surface 10B of the gypsum board 10, and the dew condensation water permeates from the back surface 10B to the front surface 10A of the gypsum board 10. When the dew condensation water permeates the gypsum board 10, the anti-mold agent in the gypsum core 11 is dissolved into the dew condensation water, and moves from the back surface 10B to the front surface 10A by the water. Therefore, when the dew condensation water permeates the gypsum board 10, the concentration of the anti-mold agent in the vicinity of the front surface 10A of the gypsum board 10 can be further increased, and the generation of mold on the front surface 10A of the gypsum board 10 can be particularly prevented.

[0059] Furthermore, even when the gypsum board 10 is used for a wall material or the like other than the ceiling board, the same effect can be obtained by the dew condensation water generated on the back surface 10B of the gypsum board 10.

[0060] However, when the gypsum core 11 contains 0.1 parts by mass or more of the waterproofing agent with respect to 100 parts by mass of the gypsum, it is difficult for the dew condensation water to pass through the gypsum core 11, and it is difficult to collect the anti- mold agent on the front surface side of the gypsum board 10. Therefore, as described above, it is preferable that the content of the waterproofing agent in the gypsum core 11 is sufficiently reduced, preferably to less than 0.1 parts by mass with respect to 100 parts by mass of the gypsum. More preferably, the gypsum core 11 contains no waterproofing agent, i.e. zero parts by mass waterproofing agent. (4) Chamfering The gypsum board 10 of the present embodiment may be chamfered on the outer periphery of the front surface 10A, that is, on sides 131, 132, 133, and 134.

[0061] Since the outer periphery of the front surface 10A is chamfered, when the gypsum boards 10 of the present embodiment are arranged side by side to form a wall, a ceiling, or the like, a space between the gypsum boards 10 as well as a shadow caused by a difference in thickness between the gypsum boards 10 can be made inconspicuous, and the design property can be enhanced. (5) Application Although the gypsum board 10 of the present embodiment can be used for various applications in which the gypsum board 10 is required, it is preferably used for applications in which an anti-mold performance is required because it contains an anti-mold agent.

[0062] In particular, there has been a case where a temperature difference occurs between the surface of the ceiling board constituting the ceiling, which is located on the indoor side, and the back surface, which is the other surface away from the indoor side, such as the back of the ceiling, etc. As a result, depending on the humidity or the like of the environment in which the gypsum board is installed, there has been a case where condensation occurs on the front surface and the back surface of the gypsum board, and mold is generated. In addition, the vicinity of the ventilation hole of the air conditioner embedded in the ceiling and the duct of the air conditioner are prone to condensation due to a temperature difference.

[0063] Therefore, the gypsum board used for the ceiling board, etc. is particularly susceptible to mold generation, and a gypsum board capable of suppressing mold generation has been required. Therefore, the gypsum board of the present embodiment is preferably gypsum board for the ceiling.

[0064] As described above, the existing gypsum board for the ceiling is prone to mold formation, but the use of the gypsum board of the present embodiment for the ceiling can suppress the formation of mold in particular and exhibit a high effect. [Interior material] The interior material of the present embodiment is a structural material for partitioning an indoor space. The interior material of the present embodiment can be used for a ceiling or a wall, for example. Hereinafter, a ceiling structure (ceiling structural material) using the interior material of the present embodiment for a ceiling will be described as an example.

[0065] An interior material 40 of the present embodiment can include the gypsum board 10 according to an aspect of the present disclosure. In the interior material 40 of the present embodiment, the coating layer 13 can be arranged on the indoor side.

[0066] As shown in FIG. 4, in the interior material 40 of the present embodiment, the gypsum board 10 can be fixed to a base such as a furring channel 41, and the furring channel 41 can be fixed to the ceiling through, for example, a hanger or a carrying channel (not illustrated).

[0067] Although FIG. 4 shows an example in which the gypsum board 10 is directly fixed to the furring channel 41, the gypsum board 10 can also be fixed to the furring channel 41 through a metal fitting (not illustrated).

[0068] Then, as shown in FIG. 4, the front surface 10A, which is a surface on which the coating layer 13 of the gypsum board 10 is disposed, can be positioned on the indoor side, that is, on the lower side in FIG. 4.

[0069] Here, a case in which the interior material of the present embodiment is used for a ceiling is shown as an example, but when it is used for a wall, studs or the like can be used instead of the furring member as a base.

[0070] Since the interior material 40 of the present embodiment includes the gypsum board 10 according to one aspect of the present disclosure, the formation of mold on the front surface 10A or the like of the gypsum board 10 can be particularly suppressed. Therefore, deterioration of appearance caused by mold or the like can be prevented. [Method for manufacturing gypsum board] The method for manufacturing gypsum board according to the present embodiment can include a gypsum slurry preparation step, a molding step, a curing step, and a coating layer formation step.

[0071] The gypsum board according to one aspect of the present disclosure can be manufactured by the method for manufacturing gypsum board according to the present embodiment. For this reason, a partial description of matters already described with regard to gypsum board will be omitted. (1) Gypsum slurry preparation step In the gypsum slurry preparation step, a gypsum slurry can be prepared by mixing an anti-mold agent having a solubility in water of 100 ppm or more, calcined gypsum, and water.

[0072] For example, a gypsum slurry can be prepared by kneading these raw material components with a mixer or the like. Various additives can be added to the gypsum slurry as needed. Since the anti-mold agent has already been described, calcined gypsum and additives other than the anti-mold agent will be described. (Calcined gypsum) Calcined gypsum, also called calcium sulfate 1 / 2 hydrate, is an inorganic composition having hydraulic properties. As the calcined gypsum, <semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>-calcined gypsum or <semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>-calcined gypsum alone or a mixture of both can be used. The <semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>-calcined gypsum is obtained by calcining in the atmosphere gypsum obtained by mixing natural gypsum, by-product gypsum, flue gas desulfurization gypsum, and recycled gypsum such as waste gypsum board, or the like, alone or in a combination thereof. The <semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>-calcined gypsum is obtained by calcining in water (including steam) gypsum obtained by mixing natural gypsum, by-product gypsum, flue gas desulfurization gypsum, and recycled gypsum such as waste gypsum board, or the like, alone or in a combination thereof.

[0073] When a gypsum board is manufactured, calcined gypsum used as a raw material preferably contains β-calcined gypsum, and more preferably, the main component of calcined gypsum used as a raw material of the gypsum board is <semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>-calcined gypsum. The main component of calcined gypsum used as a raw material of the gypsum board is <semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>-calcined gypsum, which means that <semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>-calcined gypsum occupies more than 50% in mass ratio of the calcined gypsum used as a raw material of the gypsum board. In the production of the gypsum board, the calcined gypsum used as a raw material may be composed only of the <semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>-calcined gypsum.

[0074] In order to produce the <semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>-calcined gypsum, it is necessary to pressure-bake a dihydrate gypsum such as natural gypsum in water or steam by using an autoclave. In contrast to this, the <semantics>β<annotation encoding="application / x-tex">\beta< / annotation>< / semantics>-calcined gypsum can be produced by pressure-baking a dihydrate gypsum such as natural gypsum in the atmosphere, and the β-calcined gypsum can be produced with higher productivity than the <semantics>α<annotation encoding="application / x-tex">\alpha< / annotation>< / semantics>-calcined gypsum. (Additives) The additives include, for example, one kind or two or more kinds selected from a group including adhesiveness enhancers, inorganic fibers, lightweight aggregates, refractory materials, coagulation retardants, coagulation accelerators, water reducing agents, foaming agents, foam diameter adjusters, organic carboxylic acids, organic carboxylates, organic phosphate compounds, and the like.

[0075] The adhesiveness enhancers include starch, polyvinyl alcohol, and the like. The adhesiveness enhancers can enhance the adhesiveness between the cured gypsum slurry and the board liner paper sheet.

[0076] Examples of the inorganic fiber include glass fiber, and the like.

[0077] Examples of the refractory material include vermiculite, and the like.

[0078] Examples of the foaming agent include sodium alkyl sulfate, alkyl ether sulfate, sodium alkyl benzene sulfonate, polyoxyethylene alkyl sulfate, and the like.

[0079] Examples of the foam diameter adjuster include sulfosuccinate-type surfactant and the like.

[0800] Examples of the organic phosphate compounds include sodium trimetaphosphate and the like.

[0081] The raw material of the gypsum slurry may be kneaded all at once or in multiple steps. For example, only a solid component may be mixed to form a gypsum composition, and then the gypsum composition and the remaining liquid component may be kneaded to form a gypsum slurry.

[0082] Foam may also be added to and mixed with the gypsum slurry for the purpose of adjusting the specific gravity of the gypsum core. When foam is to be added to the gypsum slurry, the timing of adding the foam is not particularly limited. For example, raw materials for the gypsum slurry including the foam may be mixed all at once. The foam may also be added to the gypsum slurry after preparing the gypsum slurry containing components other than the foam.

[0083] In the gypsum core obtained by curing the gypsum slurry, the content of the waterproofing agent may be less than 0.1 parts by mass based on 100 parts by mass of gypsum. The gypsum core 11 need not necessarily contain the waterproofing agent. Therefore, when the gypsum slurry is prepared, it is preferable that the waterproofing agent is not added to the gypsum slurry, or even when the waterproofing agent is added to the gypsum slurry, the content of the waterproofing agent is adjusted to be within the above range. (2) Molding step In the molding step, after the gypsum slurry is arranged between the board liner paper sheets 12, the gypsum slurry can be molded into a plate shape.

[0084] Concretely, for example, the gypsum slurry is arranged between the gypsum board liner paper sheets and passed through a molding machine, whereby a gypsum slurry molded body can be produced. (3) Curing step In the curing step, the gypsum slurry can be cured. In the curing step, a gypsum slurry cured body including the gypsum core 11 obtained by curing the gypsum slurry and the board liner paper sheet 12 disposed on each of the first main surface of the gypsum core and the second main surface positioned opposite to the first main surface can be obtained.

[0085] The curing step can be carried out by forming needle-like crystals of gypsum dihydrate by a hydration reaction of calcined gypsum (gypsum hemihydrate) contained in the gypsum raw material in the gypsum slurry, which coagulates and solidifies. Therefore, in the gypsum slurry molded body formed in the molding step, the calcite in the gypsum raw material added to the gypsum slurry reacts with water, and the hydration reaction of calcite progresses, whereby the curing step can be performed. (4) Coating layer formation step In the coating layer formation step, a coating material is applied to the surface of the board liner paper sheet 12 on the first main surface 11A of the gypsum core 11, the surface being positioned opposite to the surface of the board liner paper sheet 12 facing the gypsum core 11, thereby forming the coating layer 13.

[0086] Resins usable for the coating material (coating liquid) have already been described as resins contained in the coating layer 13, and therefore, description thereof is omitted. In the case where the coating layer 13 is formed after coating the coating material, since the coating layer 13 only needs to contain a desired resin, a precursor of a resin or the like may be used for the coating material.

[0087] When the coating layer 13 contains an anti-mold agent, the coating material used in the coating layer formation step may contain an anti-mold agent. The anti-mold agent used for the coating material is not particularly limited, but for example, the anti-mold agent already described may be suitably used.

[8800] Various solvents may be mixed into the coating material for the purpose of adjusting the viscosity or the like of the coating material such that a coating layer having a desired thickness can be formed while preventing liquid dripping or the like.

[0089] A specific means for applying the coating material to the board liner paper sheet is not particularly limited, and any method such as a roll coater, a flow coater, or spraying may be used. (5) Optional steps The method for producing the gypsum board of the present embodiment may further include any optional steps. Specifically, for example, it may include one or multiple steps selected from a group including a recess formation step, a chamfering step, a cutting step, and a drying step described in the following. (5-1) Recess formation step In the recess formation step, recesses can be formed in the first main surface 11A of the gypsum core 11.

[0090] In the recess formation step, a specific method for forming the recesses is not particularly limited, but for example, after a molding step or a second cutting step, the recesses can be formed by pressing a die or the like against the surface of the gypsum slurry molded body to be the first main surface 11A of the gypsum core 11.

[0091] In the recess formation step, it is preferable to form the recesses with a force and a depth sufficient not to damage the board liner paper sheet 12. The recess formation step can be performed, for example, before the coating layer formation step. (5-2) Chamfering step In the chamfering step, the outer periphery of the front surface 10A of the gypsum board 10, that is, the sides 131, 132, 133, and 134 can be chamfered.

[0092] The method of chamfering is not particularly limited, but the outer periphery of the front surface 10A of the gypsum board 10 can be polished by a polishing machine or the like to perform chamfering. The chamfering step can be performed, for example, after the coating layer formation step. (5-3) Cutting step In the cutting step, the gypsum slurry molded body can be cut by a cutter.

[0093] After the gypsum slurry molded body is formed in the molding step, the gypsum slurry is gradually cured in the curing step. Therefore, the cutting step can be performed, for example, during the curing step or after the curing step is completed. However, it is preferable to perform the cutting step after the curing step has progressed to the extent that the gypsum slurry molded body can be cut.

[0094] The cutting step can be performed a plurality of times. Therefore, the method for producing the gypsum board according to the present embodiment can include, for example, a first cutting step which can be called a rough cutting step. Furthermore, it can also include a second cutting step.

[0095] In the first cutting step, the gypsum slurry molded body can be cut to a desired size according to, for example, the size of a dryer used in a drying step described in the following.

[0096] The second cutting step can be carried out, for example, after the drying step, and can be cut to obtain a desired product size. (5-4) Drying step In the drying step, the gypsum slurry molded body can be dried. In the drying step, excess moisture contained in the gypsum slurry molded body can be dried. It is preferable to supply the gypsum slurry molded body after the curing step to the drying step. The drying step can be carried out by forcibly drying the gypsum slurry molded body by using a dryer.

[0097] The method of forcibly drying the gypsum slurry molded body by a dryer is not particularly limited, but for example, the dryer can be provided on a conveyance path of the gypsum slurry molded body, and the gypsum slurry molded body can be continuously dried by passing the gypsum slurry molded body through the dryer. In addition, the gypsum slurry molded body can be carried into the dryer to dry the gypsum slurry molded body for each batch. EXAMPLES

[0098] Specific examples will be described in the following, but the present invention is not limited to these examples. (1) Method for evaluating anti-mold performance of gypsum board Anti-mold performance was evaluated by the method described in a test method B for plastic products (measurement of mold growth inhibition effect) described in Appendix A of JIS Z 2911:2019, "Test Methods for Mold Resistance", while adding fungal species as described in the following.

[0099] Specifically, a gypsum board specimen cut into 4 cm square pieces was placed on a glucose-added mineral salt medium having a thickness of about 5 mm. Then, 1 mL of mixed spore suspension adjusted such that the number of spores per 1 fungal species was about <semantics>106<annotation encoding="application / x-tex">10^6< / annotation>< / semantics> / mL was sprayed onto the gypsum board specimen.

[0100] For the molds used to prepare mixed spore suspensions, five defined species: Aspergillus (NBRC105649), Penicillium (NBRC100533), Pecilomyces (NBRC107725), Trichoderma (NBRC6355), and Ketmium (NBRC6347), plus Cladosporium (NBRC6348), Aureobasidium (NBRC6353), and Altanaria (NBRC106339) were used.

[0101] The gypsum board specimens sprayed with the mixed spore suspension were placed in an environment with a temperature of 29±1°C and a humidity of 95%RH or more for four weeks to cultivate molds. The gypsum board specimens after four weeks were evaluated on a scale of "0" to "5" (six levels) based on the following criteria. A value of "0" indicates the highest anti-mold performance, and the higher the value, the lower the anti-mold performance. A value of "0" or "1" indicates sufficient anti-mold performance. (Evaluation criteria) 0: No growth of mold is observed with the naked eye or under a microscope. 1: Growth of mold cannot be confirmed with the naked eye, but can be confirmed under a microscope. 2: The percentage of the area covered by mold on the surface of the gypsum board specimen is 25% or less. 3: The percentage of the area covered by mold on the surface of the gypsum board specimen is more than 25% but less than 50%. 4: Of the surface of the gypsum board specimen, the ratio of the area covered with mold is 50% or more and less than 100%. 5: The surface of the gypsum board specimen is completely covered with mold. (2) Production conditions of gypsum board in experimental examples Production conditions of gypsum board in each of the experimental examples are described in the following. Experimental Examples 1 to 19 are examples, and Experimental Examples 20 to 39 are comparative examples. [Experimental Example 1] Gypsum slurry was prepared by mixing calcined gypsum, water, an anti-mold agent, and starch (gypsum slurry preparation step). The anti-mold agent was added to have a mass ratio of 100 ppm relative to the gypsum dihydrate when calcined gypsum was gypsum dihydrate.

[0102] The obtained gypsum slurry was placed between the board liner paper sheets and molded into a board shape to produce a gypsum slurry molded body (molding step).

[0103] Then, the obtained gypsum slurry molded body was cured (curing step).

[0104] After the curing step, the gypsum slurry molded body was cut and dried to produce a gypsum board (cutting step and drying step).

[0105] After the drying step was completed, a coating material, which is a mixture of an anti-mold agent and an acrylic resin, was applied to the face opposite to the gypsum core 11 of the board liner paper sheet 12 (the first board liner paper sheet 121) located on the first main surface 11A of the gypsum core 11 to form a coating layer (coating layer formation step). The coating material was applied (coated) with a paint roller such that the coating thickness was 0.1 mm (about 100 g / m2). The anti-mold agent was added such that the mass ratio of the anti-mold agent relative to gypsum dihydrate was 20 ppm when the calcined gypsum contained in the gypsum core was gypsum dihydrate.

[0106] The anti-mold agent used for the gypsum core and the coating layer was imazalil (IMZ) as shown in a "type, solubility, and amount of anti-mold agent" area in Table 1, and the solubility in water was 100 ppm or more. In Table 1, when the solubility of the anti-mold agent used for the gypsum core in water is 100 ppm or more, "<semantics>○<annotation encoding="application / x-tex">\bigcirc< / annotation>< / semantics>" is added to the column of "solubility in water".

[0107] When the average value of the thickness of the coating layer of the obtained gypsum board was measured and calculated, it was confirmed that the average value of the thickness of the coating layer was 0.1 mm, which was the same as the coating thickness of the coating layer. In other experimental examples, the average value of the thickness of the coating layer was also the same as the coating thickness of the coating layer.

[0108] In addition, since no waterproofing agent was added to the gypsum slurry, the content ratio of the waterproofing agent in the gypsum core 11 is 0. The same can be said to the following Experimental Examples 2 to 32. [Experimental Examples 2 to 8] A gypsum board was manufactured and evaluated under the same conditions as those in the Experimental Example 1, except that the type of anti-mold agent added to the gypsum core and coating layer was changed to the material as shown in Table 1. The evaluation results are shown in Table 1. [Experimental Examples 9 to 12] The resin used for the coating material was changed from acrylic resin to the resin shown in the column of "resin for coating layer" in Table 1, and a gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 2 except that the coating layer was formed by using the coating material. The evaluation results are shown in Table 1. [Experimental Examples 13 and 14] When the coating material was prepared, an anti-mold agent was added such that the mass ratio of the anti-mold agent relative to gypsum dihydrate was the amount as shown in the column of "amount mixed in coating material" in Table 1 when the calcined gypsum contained in the gypsum core was gypsum dihydrate. Then, a gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 2 except that the coating layer was formed by using the coating material. The evaluation results are shown in Table 1. [Experimental Examples 15 and 16] When the coating layer was formed, the coating thickness of the coating material was the value as shown in the column of "coating layer thickness" in Table 1. A gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 2 except for the above points. The evaluation results are shown in Table 1. [Experimental Examples 17 to 19] A gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 1 except that the anti-mold agent added to the gypsum core was the material as shown in Table 1 and the anti-mold agent was not added to the coating layer. The evaluation results are shown in Table 1. [Experimental Example 20] A gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 1 except that the anti-mold agent was not added to the gypsum core and the coating layer. The evaluation results are shown in Table 1. [Experimental Examples 21 and 22] A gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 1 except that the anti-mold agent added to the gypsum core was the material as shown in Table 1 and the coating layer was not formed. The evaluation results are shown in Table 1. [Experimental Example 23] A gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 1 except that the anti-mold agent added to the gypsum core was the material as shown in Table 1 and the anti-mold agent was not added to the coating layer. The evaluation results are shown in Table 1. [Experimental Example 24] A gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 1 except that the anti-mold agent added to the gypsum core and the coating layer was the material as shown in Table 1. The evaluation results are shown in Table 1. [Experimental Examples 25 and 26] When the coating material was prepared, an anti-mold agent was added such that, when the calcined gypsum contained in the gypsum core was gypsum dihydrate, the mass ratio of the anti-mold agent relative to gypsum dihydrate was the amount as shown in the "amount mixed in coating material" column in Table 1. The gypsum board was manufactured and evaluated under the same conditions as those in Experimental Example 24 except that the coating layer was formed by using the coating material. The evaluation results are shown in Table 1. [Experimental Examples 27 and 28] When the coating layer was formed, the coating thickness of the coating material was set to the value as shown in the column of "coating layer thickness" in Table 1. The gypsum board was manufactured and evaluated under the same conditions as those of Experimental Example 24 except for the above points. The evaluation results are shown in Table 1. [Experimental Examples 29 to 32] A gypsum board was manufactured and evaluated under the same conditions as those of Experimental Example 1 except that no anti-mold agent was added to the gypsum core and the anti-mold agent added to the coating layer was the material as shown in Table 1. The evaluation results are shown in Table 1. [Experimental Examples 33 to 39] A gypsum board was manufactured and evaluated under the same conditions as those of Experimental Example 1 except that the anti-mold agent added to the gypsum core and the coating layer was the material as shown in Table 1 and waterproofing agent was added to the gypsum core. The evaluation results are shown in Table 1.

[0109] Organopolysiloxane was used as the waterproofing agent, and was added such that the ratio of the waterproofing agent per 100 parts by mass of gypsum dihydrate, when the gypsum contained in the gypsum core was regarded as gypsum dihydrate, was the value as shown in the column of the waterproofing agent in Table 1.

[0110] [Table 1] [Image disponible dans le document PDF, Image available in the PDF document] From the above results, it was confirmed that the gypsum boards of Experimental Examples 1 to 19 demonstrated excellent anti- mold performance. That is, it was confirmed that the anti-mold performance could be enhanced when the gypsum core 11 had a coating layer, contained an anti-mold agent having a solubility in water of 100 ppm or more, and the content of the waterproofing agent in the gypsum core was set within a predetermined range. (Clauses) (1) A gypsum board according to one aspect of the present disclosure including: a gypsum core; a board liner paper sheet arranged on each of a first main surface of the gypsum core and a second main surface of the gypsum core located opposite to the first main surface; and a coating layer disposed on a surface of the board liner paper sheet located on the first main surface of the gypsum core, the surface being a surface of the board liner paper sheet opposite to the surface of the board liner paper sheet facing the gypsum core, wherein the gypsum core includes an anti-mold agent having a solubility in water of 100 ppm or more, and content of a waterproofing agent in the gypsum core is less than 0.1 parts by mass per 100 parts by mass of gypsum. (2) In (1), the coating layer may include an anti-mold agent. (3) In (2), the gypsum core may include at least one kind of anti-mold agent different from the anti-mold agent included in the coating layer. (4) In any one of (1) to (3), an average value of a thickness of the coating layer may be within a range from 0.01 mm to 0.3 mm. (5) In any one of (1) to (4), the coating layer may include a resin. (6) In any one of (1) to (5), the first main surface of the gypsum core may include a recess. (7) In any one of (1) to (6), a gypsum board may be a gypsum board for a ceiling. (8) The interior material according to one aspect of the present disclosure is an interior material used for a ceiling or a wall for partitioning an indoor space, and includes any one of the gypsum boards in (1) to (7), wherein the coating layer is positioned on an indoor side. (9) A method for producing a gypsum board according to one aspect of the present disclosure includes: a gypsum slurry preparation step of preparing a gypsum slurry by mixing an anti-mold agent having a solubility in water of 100 ppm or more, calcined gypsum, and water; a molding step of arranging the gypsum slurry between the board liner paper sheets and then molding the gypsum slurry into a plate shape; a curing step of obtaining a gypsum slurry cured body including a gypsum core obtained by curing the gypsum slurry; and the board liner paper sheets disposed on a first main surface of the gypsum core and on a second main surface of the gypsum core opposite the first main surface; and a coating layer formation step of applying a coating material to a surface of the board liner paper sheet on the first main surface of the gypsum core, the surface being positioned opposite to a surface of the board liner paper sheet facing the gypsum core, thereby forming a coating layer, wherein content of a waterproofing agent in the gypsum core is less than 0.1 parts by mass per 100 parts by mass of gypsum.

[0111] Although the gypsum board, the interior material, and the method for manufacturing the gypsum board have been described above with reference to embodiments and the like, the present invention is not limited to the above embodiments and the like. Various modifications and changes are possible within the scope of the present invention described in the claims.

[0112] This application claims priority from Japanese Patent 5 Application No. 2024-046736, filed in the Japanese Patent Office on March 22, 2024, and the entire contents of Japanese Patent Application No. 2024-046736. REFERENCE SIGNS LIST 10

[0113] 10 Gypsum board 10A Front surface 10B Back surface 11 Gypsum core 15 11A First main surface 11B Second main surface 12 Board liner paper sheet 121 First board liner paper sheet 122 Second board liner paper sheet 20 121A First surface 121B Second surface 13 Coating layer 131 Side 132 Side 25 133 Side 134 Side T13 Thickness 31 Recess 31A Bottom surface 30 31B Side surface 32 Projection 40 Interior material 41 Furring channel

Claims

1. A gypsum board comprising: a gypsum core; a board liner paper sheet arranged on each of a first main surface of the gypsum core and a second main surface of the gypsum core located opposite to the first main surface; and a coating layer disposed on a surface of the board liner paper sheet located on the first main surface of the gypsum core, the surface being a surface of the board liner paper sheet opposite to the surface of the board liner paper sheet facing the gypsum core, wherein the gypsum core includes an anti-mold agent having a solubility in water of 100 ppm or more, and content of a waterproofing agent in the gypsum core is less than 0.1 parts by mass per 100 parts by mass of gypsum.

2. The gypsum board according to claim 1, wherein the coating layer includes an anti-mold agent.

3. The gypsum board according to claim 2, wherein the gypsum core includes at least one kind of anti-mold agent different from the anti-mold agent included in the coating layer.

4. The gypsum board according to any one of claims 1 to 3, wherein an average value of a thickness of the coating layer is within a range from 0.01 mm to 0.3 mm.

5. The gypsum board according to any one of claims 1 to 3, wherein the coating layer includes a resin.

6. The gypsum board according to any one of claims 1 to 3, wherein the first main surface of the gypsum core includes a recess.

7. The gypsum board according to any one of claims 1 to 3 is a gypsum board for a ceiling.

8. An interior material used for a ceiling or a wall for partitioning an indoor space, the interior material comprising: the gypsum board according to any one of claims 1 to 3, wherein the coating layer is positioned on an indoor side.

9. A method for producing a gypsum board comprising: a gypsum slurry preparation step of preparing a gypsum slurry by mixing an anti-mold agent having a solubility in water of 100 ppm or more, calcined gypsum, and water; a molding step of arranging the gypsum slurry between board liner paper sheets and then molding the gypsum slurry into a plate shape; a curing step of obtaining a gypsum slurry cured body including a gypsum core obtained by curing the gypsum slurry; and the board liner paper sheets disposed on a first main surface of the gypsum core and on a second main surface of the gypsum core opposite the first main surface; and a coating layer formation step of applying a coating material to a surface of the board liner paper sheet on the first main surface of the gypsum core, the surface being positioned opposite to a surface of the board liner paper sheet facing the gypsum core, thereby forming a coating layer, wherein content of a waterproofing agent in the gypsum core is less than 0.1 parts by mass per 100 parts by mass of gypsum.