Gypsum board, interior material, method for manufacturing gypsum board

Abstract

A gypsum board is provided, comprising: a gypsum core; a board base paper disposed on a first main surface of the gypsum core and a second main surface opposite to the first main surface; and a coating layer disposed on the surface of the board base paper on the first main surface of the gypsum core opposite to the surface opposite to the gypsum core. The gypsum core contains a mildew inhibitor with a solubility of 100 ppm or more relative to water, and the content of a waterproofing agent in the gypsum core is less than 0.1 parts by weight relative to 100 parts by weight of gypsum.

Description

Technical Field

[0001] This invention relates to gypsum board, interior decoration materials, and a method for manufacturing gypsum board. Background Technology

[0002] Patent document 1 discloses a gypsum material with antibacterial and antifungal properties, characterized in that a soluble glass that dissolves silver or copper ions is mixed into the gypsum as powder, beads or fibers.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1: Japanese Patent Application Publication No. 2-302354. Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Gypsum board has long been used as a wall and ceiling material for interior decoration.

[0008] In gypsum board used as wall and ceiling materials, a temperature difference sometimes occurs between the interior surface and the exterior surface opposite to it. As a result, depending on the humidity of the environment where the gypsum board is installed, condensation may occur on the surface and back of the gypsum board, and mold may sometimes develop on the gypsum board.

[0009] If mold grows on a gypsum board, it needs to be replaced from both an aesthetic and hygiene perspective, depending on the extent of the mold growth. Therefore, gypsum boards with materials that impart anti-mold properties to the gypsum board, such as those disclosed in Patent Document 1, have been under research to inhibit mold growth.

[0010] Furthermore, gypsum board with excellent mold resistance is required.

[0011] Therefore, one objective of this invention is to provide a gypsum board with excellent anti-mildew properties.

[0012] Methods for solving problems

[0013] To address the aforementioned issues, according to one aspect of the present invention, a gypsum board is provided, which has the following characteristics: Plaster core, The base paper for the board is disposed on the first main surface of the gypsum core and on the second main surface opposite to the first main surface, and A coating layer disposed on the surface of the board base paper opposite to the surface opposite to the gypsum core, located on the first main surface of the gypsum core. The gypsum core contains a mildew inhibitor with a solubility of more than 100 ppm relative to water. In the gypsum core, the content of waterproofing agent is less than 0.1 parts by weight relative to 100 parts by weight of gypsum.

[0014] The effects of the invention

[0015] According to one aspect of the present invention, a gypsum board with excellent anti-mildew properties can be provided. Attached Figure Description

[0016] Figure 1 This is a perspective view of a gypsum board according to one aspect of the present invention.

[0017] Figure 2 This is a cross-sectional view of a gypsum board according to one aspect of the present invention.

[0018] Figure 3 This is a cross-sectional view of a gypsum board with a concave gypsum core.

[0019] Figure 4 This is an explanatory diagram of an interior material according to one aspect of the present invention. Detailed Implementation

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, 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.

[0021] [Gypsum board]

[0022] Hereinafter, a gypsum board according to one embodiment of the present disclosure (hereinafter referred to as "Embodiment") will be described with reference to the accompanying drawings.

[0023] In addition, the attached drawings are schematic diagrams used to illustrate the structure of the plasterboard, etc. in this embodiment, and the dimensions, etc. are not accurately shown.

[0024] Figure 1 A perspective view showing the gypsum board according to this embodiment. Figure 2 , Figure 3 This is a cross-sectional view of the gypsum board according to this embodiment. Figure 3 This is an explanatory diagram showing the case where the gypsum core of the gypsum board in this embodiment has a recess on the first main surface. Therefore, it mainly utilizes... Figure 1 , Figure 2 The gypsum board of this embodiment will be described, and if necessary, it will be utilized. Figure 3 .exist Figure 1 , Figure 2 , Figure 3 In this diagram, the Z-axis is the axis along the thickness of the gypsum board, and it is the axis along the stacking direction of the gypsum core, the base paper, and the coating layer. The XY plane is the plane perpendicular to the Z-axis.

[0025] (1) Regarding the construction of gypsum board

[0026] like Figure 1 and Figure 2 As shown, the gypsum board 10 of this embodiment has a gypsum core 11, board base paper 12, and coating layer 13.

[0027] (Plaster core)

[0028] As described later in the method for manufacturing gypsum board, the gypsum core 11 is a cured gypsum slurry. The gypsum core 11 may contain gypsum, specifically dihydrate gypsum, various additives, and a mildew inhibitor. The various additives that the gypsum core 11 may contain will be explained in the method for manufacturing gypsum board. Furthermore, the mildew inhibitor will be explained later.

[0029] like Figure 3 As shown, the first main surface 11A of the plaster core 11 of the plasterboard 10 in this embodiment may include a recess 31. When the plasterboard 10 of this embodiment is used as an interior material such as wall material or ceiling material, the first main surface 11A is the surface located on the interior side and is used to fix screws or the like to the substrate. Therefore, since the first main surface 11A of the plaster core 11 has a recess 31, columnar patterns or marble patterns can be formed on the first main surface 11A of the plasterboard 10. As a result, screws or the like that impacting the first main surface 11A of the plasterboard 10 become less noticeable, and the appearance design can be improved.

[0030] (Base paper for the board)

[0031] The board base paper 12 can be disposed on a second main surface 11B opposite to the first main surface 11A and the first main surface 11A of the gypsum core 11. The board base paper 12 disposed on the first main surface 11A can be designated as first board base paper 121, and the board base paper 12 disposed on the second main surface 11B can be designated as second board base paper 122, etc. Figure 1 In this text, the first sheet base paper 121 and the second sheet base paper 122 are described as separate, unconnected components, but the description is not limited to this. The first sheet base paper 121 and the second sheet base paper 122 may be configured to cover the sides 11C of the plaster core 11 (see [link to documentation]). Figure 2 A single continuous sheet of PCB material can be used, or two or more sheets can be glued together to form a single unit. Additionally, such as... Figure 1 and Figure 2 As shown, the first board base paper 121 and the second board base paper 122 can be different parts that are not connected anywhere.

[0032] The first main surface 11A and the second main surface 11B become surfaces that intersect with the thickness direction of the gypsum board 10. When the gypsum board 10 is used as an interior material such as a wall material or ceiling material, the first main surface 11A and the second main surface 11B become wall or ceiling surfaces.

[0033] As described above, the plaster core 11 may also have a recess 31 on the first main surface 11A. When the plaster core 11 has a recess 31 on the first main surface 11A, such as Figure 3 As shown, the preferred board paper 12 is also disposed on the bottom surface 31A and side surface 31B of the recess 31 of the plaster core 11. That is, when the plaster core 11 has a recess 31, the preferred board paper 12 also has a recess at a position corresponding to the recess 31 of the plaster core 11.

[0034] There are no particular limitations on the base paper 12 for board, and various base papers used in gypsum board can be used, for example.

[0035] (Coating layer)

[0036] The coating layer 13 can be disposed on the board base paper 12 located on the first main surface 11A of the gypsum core 11, that is, the surface of the first board base paper 121 opposite to the second surface 121B, and the first surface 121A is the surface opposite to the gypsum core 11.

[0037] The coating layer 13 may cover the entire first surface 121A of the first board base paper 121, or it may cover only a portion of the first surface 121A.

[0038] In addition, the second board base paper 122 located on the second main surface 11B of the gypsum core 11 is not provided with a coating layer, and the second board base paper 122 can be configured to include a back surface 10B, which serves as the outer surface of the gypsum board 10.

[0039] The gypsum board 10 of this embodiment has a coating layer 13, which can prevent the antifungal agent contained in the gypsum core 11 from flowing out to the outside, and can also increase the concentration of the antifungal agent near the surface 10A of the gypsum board 10. Therefore, the antifungal performance of the gypsum board 10 can be improved by having a coating layer 13.

[0040] The coating layer 13 may also contain a mildew inhibitor. That is, the gypsum core 11 and the coating layer 13 of the gypsum board 10 in this embodiment may each contain a mildew inhibitor.

[0041] The coating layer 13 can be formed, for example, by applying a coating material to the first side 121A of the base paper 121 on the first board. If the coating layer 13 contains a mildew inhibitor, the coating material may also contain a mildew inhibitor.

[0042] The coating used to form the coating layer 13 may also include a resin. If the coating contains a mildew inhibitor, the mildew inhibitor may be fixed onto the first side 121A of the first board base paper 121.

[0043] That is, the coating layer 13 may also include a resin. As the resin contained in the coating layer 13, one or more resins selected from acrylic resin, acrylamide resin, polyurethane resin, silicone resin, epoxy resin, etc. can be used.

[0044] As described above, the plaster core 11 may also have a recess 31 on the first main surface 11A. When the plaster core 11 has a recess 31 on the first main surface 11A, the coating layer 13 may be provided on the surface of the bottom surface 31A or the side surface 31B of the recess 31, or it may not be provided. For example, as Figure 3 As shown, the coating layer 13 may be applied only to the surface of the protrusions 32 disposed between the recesses 31 of the plaster core 11. In this case, the board base paper 12 is disposed on the surface of the bottom surface 31A or the side surface 31B of the recesses 31.

[0045] The thickness T13 of the coating layer 13 is not particularly limited, but the average value of the thickness T13 of the coating layer 13 can be, for example, above 0.01 mm and below 0.3 mm.

[0046] By ensuring that the average thickness of the coating layer 13 is 0.01 mm or more, the strength of the coating layer 13 can be sufficiently improved. Furthermore, when the coating layer 13 contains a mildew inhibitor, ensuring that the average thickness of the coating layer 13 is 0.01 mm or more allows the coating layer 13 to contain a sufficient amount of mildew inhibitor, thereby significantly improving the mildew resistance of the gypsum board 10.

[0047] By making the average thickness of the coating layer 13 less than 0.3 mm, the coating layer 13 can be easily formed, thereby improving the productivity of gypsum board.

[0048] The average thickness of coating layer 13 can be determined by following these steps.

[0049] The thickness of the gypsum board before coating layer 13 is formed and the thickness of the gypsum board after coating layer 13 is formed can be measured separately for each gypsum board according to the thickness measurement method specified in JIS A 6901 (2014) "Gypsum Board Products". Specifically, six measurements are taken at equal intervals on the inner side of the sample, within 25 mm from the end face and at least 80 mm from both sides, and the average value of the measurements is obtained to determine the thickness of each gypsum board. Alternatively, if the width of the evaluation area is 606 mm or less, the thickness can be measured at three locations.

[0050] Then, the thickness of the coating layer can be calculated using the thickness of the gypsum board before and after the formation of coating layer 13, i.e., the average value of the coating thickness.

[0051] (Coating thickness) = (Thickness of gypsum board after coating) - (Thickness of gypsum board before coating)

[0052] If a coating layer has already been formed, the gypsum board after the coating layer has been removed can be used for evaluation as if it were the gypsum board before the coating layer was formed. Alternatively, gypsum boards before and after the coating layer can be made using other materials for evaluation.

[0053] (2) Regarding antifungal agents

[0054] The inventors of this invention have conducted research on gypsum board with excellent anti-mildew properties.

[0055] From the perspective of improving the mildew resistance of gypsum board 10, a mildew inhibitor can be added to gypsum board 10. When adding a mildew inhibitor to gypsum board 10, adding it to the gypsum core 11 can be considered. However, when adding a mildew inhibitor to the gypsum core 11, the effect of improving the mildew resistance of the gypsum board is mainly on the surface 10A of gypsum board 10 and the mildew inhibitor located nearby. Therefore, when adding a mildew inhibitor to the gypsum core 11, since the interior of the gypsum core 11 also contains a relatively large amount of mildew inhibitor, there is a problem of an increased proportion of mildew inhibitors that do not contribute to improving mildew resistance.

[0056] Therefore, the inventors of this invention conducted further research. As a result, the gypsum core 11 of the gypsum board 10 of this embodiment can contain a mildew inhibitor. Furthermore, the gypsum core 11 can contain a mildew inhibitor with a solubility of 100 ppm or more relative to water. According to the inventors' research, by adopting the above-described configuration, the mildew resistance of the gypsum board 10 can be improved.

[0057] By containing a water-soluble antifungal agent with a solubility of 100 ppm or more relative to water in the gypsum core 11, the antifungal agent can be dissolved in the water content of the gypsum slurry used in manufacturing the gypsum core 11. Furthermore, during the manufacturing of the gypsum core 11, gypsum slurry is placed between the board base paper and the gypsum board 12. During the molding process, the antifungal agent in the gypsum slurry is absorbed into the board base paper 12, increasing the concentration of the antifungal agent in the board base paper 12. Therefore, by containing an antifungal agent with a solubility of 100 ppm or more relative to water in the gypsum core 11, the antifungal properties of the surface 10A of the gypsum board 10 can be sufficiently improved even without directly adding the antifungal agent to the board base paper 12.

[0058] The amount of antifungal agent contained in the gypsum core 11 is not particularly limited and can be selected according to the required antifungal performance. For example, if it is assumed that all the gypsum contained in the gypsum core is dihydrate gypsum, the antifungal agent is preferably contained in a proportion of 50 ppm to 1000 ppm by mass relative to dihydrate gypsum, and more preferably in a proportion of 100 ppm to 500 ppm.

[0059] By containing a mildew inhibitor in the gypsum core 11 at a mass ratio of 50 ppm or more relative to dihydrate gypsum, gypsum boards with particularly excellent mildew resistance can be produced.

[0060] The results show that the higher the amount of antifungal agent contained in the gypsum core 11, the higher the antifungal performance. However, even if the amount is more than 1000 ppm relative to dihydrate gypsum, it will result in excessive antifungal performance and high cost. Therefore, the gypsum core 11 preferably contains antifungal agent at a ratio of less than 1000 ppm by mass relative to dihydrate gypsum.

[0061] In such Figure 3 In the case of a gypsum board with a recess 31 formed at surface 10A in the mold shown, the surface of the first board paper 121 at the bottom surface 31A or side surface 31B of the recess 31 sometimes does not have a coating layer 13. In gypsum boards with recesses 31, if the coating layer 13 is not provided on the surface of the first board paper 121 at the bottom surface 31A or side surface 31B of the recess 31, the first board paper 121 is exposed at the bottom surface 31A or side surface 31B of the recess 31. Therefore, by improving the anti-mildew properties of the surface 10A of the gypsum board 10, especially the surface of the first board paper 121, it is also possible to prevent mold growth in areas where the coating layer 13 is not provided, such as the bottom surface 31A or side surface 31B of the recess 31.

[0062] Furthermore, for example, when the gypsum board 10 is used as a ceiling, if condensation occurs in the back surface 10B of the gypsum board 10, the condensation will penetrate from the back surface 10B to the surface 10A. When the condensation penetrates the gypsum board 10, the antifungal agent in the gypsum core dissolves in the condensation and moves towards the surface 10A, further increasing the concentration of the antifungal agent on and near the surface 10A. Therefore, the antifungal performance of the surface 10A of the gypsum board 10 can be improved. Additionally, even when the surface 10A of the gypsum board has a recess 31 and the bottom surface 31A or side surface 31B of the recess 31 is not coated with a coating layer 13, the antifungal performance of the bottom surface 31A or side surface 31B of the recess 31 can still be further improved due to the penetration of condensation into the gypsum board 10.

[0063] In addition, as mentioned above, coating layer 13 may also contain a mildew inhibitor. By also providing a mildew inhibitor in coating layer 13, it is possible to specifically inhibit the growth of mold on the surface 10A of gypsum board 10.

[0064] The amount of antifungal agent contained in the coating layer 13 is not particularly limited and can be selected according to the required antifungal performance. For example, if it is assumed that all the gypsum contained in the gypsum core 11 is dihydrate gypsum, the antifungal agent contained in the coating layer 13 is preferably contained in a proportion of 10 ppm to 1000 ppm by mass relative to the dihydrate gypsum contained in the gypsum core, and more preferably in a proportion of 20 ppm to 500 ppm.

[0065] By containing a mildew inhibitor in the coating layer 13 at a mass ratio of 10 ppm or more relative to the dihydrate gypsum contained in the gypsum core 11, it is possible to produce a gypsum board with particularly excellent mildew resistance.

[0066] The study shows that the higher the amount of antifungal agent contained in the coating layer 13, the better the antifungal performance. However, compared with the dihydrate gypsum contained in the gypsum core 11, even a mass ratio exceeding 1000 ppm would result in excessive antifungal performance and high cost. Therefore, compared with the dihydrate gypsum contained in the gypsum core 11, the coating layer 13 preferably contains an antifungal agent at a mass ratio of 1000 ppm or less.

[0067] Since the gypsum core 11 can also contain a variety of antifungal agents, the gypsum core 11 can contain, for example, antifungal agents with a solubility of more than 100 ppm relative to water, as well as antifungal agents with a solubility of less than 100 ppm relative to water.

[0068] When the coating layer 13 contains a mildew inhibitor, the mildew inhibitor contained in the coating layer 13 is not particularly limited. Similar to the gypsum core 11, it may contain a mildew inhibitor with a solubility of 100 ppm or more relative to water, or it may contain a mildew inhibitor with a solubility of less than 100 ppm relative to water. In addition, the coating layer 13 may contain a variety of mildew inhibitors.

[0069] Therefore, the antifungal agent contained in the coating layer 13 may be one or more selected from antifungal agents with a solubility of more than 100 ppm relative to water and antifungal agents with a solubility of less than 100 ppm relative to water.

[0070] The gypsum core 11 and the coating layer 13 may contain different or the same antifungal agents. In addition, the gypsum core 11 and the coating layer 13 may each contain only one type of antifungal agent, or either or both of the gypsum core 11 and the coating layer 13 may contain two or more types of antifungal agents.

[0071] Therefore, for example, the gypsum core 11 may also contain at least one antifungal agent that is different from the antifungal agent contained in the coating layer 13.

[0072] The antifungal agent added to the gypsum core 11 and the coating layer 13 is mainly disposed near the surface 10A of the gypsum board 10, which helps to improve the antifungal performance of the surface 10A of the gypsum board 10. However, in the coating layer 13 and the gypsum core 11, the preferred antifungal agent is sometimes different because the materials disposed around the antifungal agent are different.

[0073] Therefore, by including at least one type of antifungal agent in the gypsum core 11 that is different from the antifungal agent contained in the coating layer 13, the antifungal agents contained in the gypsum core 11 and the coating layer 13 located on the surface 10A of the gypsum board 10 can be particularly optimized. Thus, the antifungal performance of the gypsum board 10 can be improved.

[0074] By including a mildew inhibitor with a solubility of 100 ppm or more relative to water in the gypsum core 11, the amount of mildew inhibitor dissolved in the gypsum slurry can be increased during the manufacture of the gypsum core 11, making it particularly easy to include mildew inhibitor in the board base paper 12.

[0075] For example, as described above, the coating layer 13 can also contain a mildew inhibitor with a solubility of less than 100 ppm relative to water. By containing a mildew inhibitor with a solubility of less than 100 ppm relative to water in the coating layer 13, the leaching of the mildew inhibitor from the coating layer 13 to the base paper 12 is suppressed, thereby significantly increasing the amount of mildew inhibitor contained in the coating layer 13. Therefore, the amount of mildew inhibitor on the surface 10A of the gypsum board 10 can be significantly increased, and the mildew resistance of the gypsum board 10 can be significantly improved.

[0076] The solubility of a fungicide relative to water can be evaluated, for example, through the following steps.

[0077] For example, a fungicide is added to water at 25°C, stirred for 10 to 20 minutes, and then subjected to solid-liquid separation to remove undissolved fungicide, collecting only the liquid fraction. The concentration of the fungicide by mass ratio in this liquid fraction can then be evaluated as the solubility of the fungicide relative to water. Water that has been thoroughly cleaned of impurities, such as distilled water, can be used as the water. Alternatively, the concentration of the fungicide in the liquid fraction can be evaluated using liquid chromatography or similar methods.

[0078] Examples of antifungal agents that can be used in the gypsum board of this embodiment include one or more selected from IPBC (3-iodo-2-propylbutylcarbamate, solubility: 156 ppm), IMZ (Imazalil, solubility: 180 ppm), OIT (2-N-octyl-4-isothiazolin-3-one, solubility: 480 ppm), BCM (methyl 2-benzimidazole carbamate, solubility: 5.6 ppm), OPP (o-phenol, solubility: 700 ppm), TBZ (2-(4-thiazolyl)-benzimidazole, solubility: 30 ppm), (solubility: 15 ppm), ZPT (zinc pyrithione, solubility: 15 ppm), and FDO (fluorodioxane, solubility: 1.8 ppm). Furthermore, all the above solubilities refer to solubility relative to water.

[0079] (3) About waterproofing agents

[0080] The waterproofing agent content of the gypsum core 11 in the gypsum board 10 of this embodiment can be less than 0.1 parts by weight relative to 100 parts by weight of gypsum. The gypsum core 11 of this embodiment may not contain a waterproofing agent. Furthermore, the aforementioned waterproofing agent content indicates the ratio of the waterproofing agent to 100 parts by weight of dihydrate gypsum, assuming the gypsum contained in the gypsum core is considered as dihydrate gypsum.

[0081] As described above, for example, when the gypsum board 10 is used for a ceiling, condensation occurs on the back surface 10B of the gypsum board 10, and sometimes the condensation permeates from the back surface 10B to the surface 10A. Furthermore, when the condensation permeates the gypsum board 10, the antifungal agent within the gypsum core 11 dissolves in the condensation and moves from the back surface 10B to the surface 10A via the water. Therefore, by allowing the condensation to permeate the gypsum board 10, the concentration of the antifungal agent near the surface 10A of the gypsum board 10 can be further increased, effectively preventing the growth of mold on the surface 10A of the gypsum board 10.

[0082] Furthermore, even when the plasterboard 10 is used as a wall material other than a ceiling, the same effect can be achieved through condensation or the like generated on the back side 10B of the plasterboard 10.

[0083] However, if the gypsum core 11 contains more than 0.1 parts by weight of waterproofing agent relative to 100 parts by weight of gypsum, condensation will have difficulty passing through the gypsum core 11, and the anti-mildew agent may have difficulty accumulating on the surface of the gypsum board 10. Therefore, as described above, the content of waterproofing agent in the gypsum core 11 is preferably sufficiently reduced, preferably less than 0.1 parts by weight relative to 100 parts by weight of gypsum, and particularly preferably, the gypsum core 11 contains no waterproofing agent, i.e., 0.

[0084] (4) About chamfers

[0085] In this embodiment, the gypsum board 10 may also be chamfered on the outer periphery of the surface 10A, namely the portions of edges 131, 132, 133, and 134.

[0086] By chamfering the outer periphery of the surface 10A, when the plasterboards 10 of this embodiment are arranged side by side to form walls, ceilings, etc., the shadows caused by the gap between the abutments of the plasterboards 10 and the difference in thickness between the boards are not obvious, thus improving the appearance design.

[0087] (5) Regarding the use

[0088] The gypsum board 10 of this embodiment can be used for various applications requiring gypsum board 10, but since it contains a mildew inhibitor, it is best used for applications requiring mildew resistance.

[0089] In particular, temperature differences sometimes occur between the interior surface of the ceiling and the exterior surface (back side), such as the inner side of the ceiling. As a result, depending on the humidity of the environment where the plasterboard is installed, condensation may form on the surface or back of the plasterboard, leading to mold growth. Additionally, condensation is prone to occur near the ventilation openings of ceiling-mounted air conditioners or in the air ducts of those air conditioners due to temperature differences.

[0090] Therefore, gypsum board used for ceilings and the like is particularly prone to mold growth, and there is a need for gypsum board that can inhibit mold growth. Therefore, the gypsum board of this embodiment is particularly preferred for ceilings.

[0091] As mentioned above, plasterboard used for ceilings in the past is prone to mold growth, but using the plasterboard of this embodiment for ceilings can effectively inhibit mold growth and achieve high efficiency.

[0092] [Interior materials]

[0093] The interior material in this embodiment is a structural material used to divide interior space. For example, the interior material in this embodiment can be used for ceilings or walls. Hereinafter, an example will be given of a ceiling structure (ceiling structural material) in which the interior material of this embodiment is used as a ceiling.

[0094] The interior material 40 in this embodiment may include the gypsum board 10 according to one aspect of the present invention. In the interior material 40 of this embodiment, the coating layer 13 may be disposed on the interior side.

[0095] like Figure 4 As shown, in the interior material 40 of this embodiment, the plasterboard 10 can be fixed to a base such as the edge 41, and the edge 41 can be fixed to the ceiling via, for example, a hanging beam or edge support not shown.

[0096] Although Figure 4An example is shown in which the plasterboard 10 is directly fixed to the edge 41, but the plasterboard 10 can also be fixed to the edge 41 via a metal component or the like, not shown.

[0097] like Figure 4 As shown, surface 10A, i.e., the surface of gypsum board 10 with the coating layer 13, can be disposed on the indoor side, i.e., disposed on... Figure 4 Below.

[0098] Here, the example of using the interior material of this embodiment for a ceiling is given. However, when using the interior material for a wall, screws or the like can be used instead of the outer edge as a base.

[0099] In the interior material 40 of this embodiment, since it includes the gypsum board 10 of one aspect of the present disclosure, it is particularly effective to suppress the growth of mold on the surface 10A of the gypsum board 10. Therefore, it is possible to prevent the deterioration of appearance caused by mold or the like.

[0100] [Manufacturing method of gypsum board]

[0101] The method for manufacturing gypsum board according to this embodiment may include a gypsum slurry preparation process, a molding process, a curing process, and a coating layer formation process.

[0102] The gypsum board manufacturing method of this embodiment can be used to manufacture the gypsum board according to one aspect of the present invention. Therefore, some descriptions of matters already described regarding the gypsum board are omitted.

[0103] (1) Plaster slurry preparation process

[0104] In the gypsum slurry preparation process, a mildew inhibitor with a solubility of more than 100 ppm relative to water, calcined gypsum, and water can be mixed to prepare gypsum slurry.

[0105] For example, these raw material components can be mixed using a mixer or similar device to prepare gypsum slurry. Various additives can also be added to the gypsum slurry as needed. Since mold inhibitors have already been described, additives other than calcined gypsum and mold inhibitors will be described.

[0106] (calcined plaster)

[0107] Calcined gypsum, also known as calcium sulfate half hydrate, is an inorganic composition with hydraulic properties. Calcined gypsum can be produced by calcining monomers of β-type calcined gypsum or α-type calcined gypsum, or mixtures thereof. β-type calcined gypsum is obtained by calcining a mixture of any monomer or combination of natural gypsum, by-product gypsum, flue gas desulfurization gypsum, and recycled gypsum such as waste gypsum board, in atmospheric conditions. α-type calcined gypsum is obtained by calcining a mixture of any monomer or combination of natural gypsum, by-product gypsum, flue gas desulfurization gypsum, and recycled gypsum such as waste gypsum board, in water (including steam).

[0108] When manufacturing gypsum board, the calcined gypsum used as raw material preferably includes β-type calcined gypsum, and the main component of the calcined gypsum used as raw material for gypsum board is preferably β-type calcined gypsum. When the main component of the calcined gypsum used as raw material for gypsum board is β-type calcined gypsum, this means that β-type calcined gypsum accounts for more than 50% by mass in the calcined gypsum used as raw material for gypsum board. In manufacturing gypsum board, the calcined gypsum used as raw material may consist solely of β-type calcined gypsum.

[0109] To manufacture α-type calcined gypsum, a high-pressure autoclave is used to calcine dihydrate gypsum such as natural gypsum under pressure in water or steam. On the other hand, β-type calcined gypsum can be manufactured by calcining dihydrate gypsum such as natural gypsum at atmospheric pressure, and β-type calcined gypsum can be manufactured more efficiently than α-type calcined gypsum.

[0110] (additive)

[0111] As an additive, for example, one or more can be selected from adhesive modifiers, inorganic fibers, lightweight aggregates, refractory materials, setting delay agents, setting accelerators, water-reducing agents, foaming agents, foam diameter adjusters, organic carboxylic acids, organic carboxylates, organophosphate compounds, etc.

[0112] Examples of adhesive modifiers include starch and polyvinyl alcohol. Adhesive modifiers can improve the adhesion between the cured gypsum slurry and the base paper for board.

[0113] Inorganic fibers include glass fibers, etc.

[0114] Refractory materials include vermiculite, etc.

[0115] Foaming agents include sodium alkyl sulfate, alkyl ether sulfate, sodium alkylbenzene sulfonate, and polyoxyethylene alkyl sulfate.

[0116] Materials for adjusting foam diameter include sulfosuccinate surfactants, etc.

[0117] Examples of organophosphate compounds include sodium trimethylphosphate.

[0118] The raw materials for gypsum slurry can be mixed in one step or in multiple stages. For example, after mixing only the solid components to form a gypsum composition, the gypsum composition can be mixed with the remaining liquid components to form a gypsum slurry.

[0119] Foam can be added or mixed into plaster slurry for purposes such as adjusting the specific gravity of the plaster core. There is no particular limitation on the timing of adding foam to plaster slurry. For example, the raw materials of plaster slurry, including foam, can be mixed together. Alternatively, foam can be added to the plaster slurry after it has been prepared with ingredients other than foam.

[0120] In the gypsum core obtained after the gypsum slurry has cured, the content of the waterproofing agent can be less than 0.1 parts by weight relative to 100 parts by weight of gypsum. The gypsum core 11 may also not contain a waterproofing agent. Therefore, when preparing the gypsum slurry, it is preferable not to add a waterproofing agent to the gypsum slurry, or even if a waterproofing agent is added, its content ratio is adjusted to be within the above-mentioned range.

[0121] (2) Molding process

[0122] In the molding process, after the gypsum slurry is placed between the base paper 12, the gypsum slurry can be molded into a board shape.

[0123] Specifically, for example, plaster slurry molded bodies can be manufactured by placing plaster slurry between the base paper of plasterboard and passing it through a molding machine.

[0124] (3) Curing process

[0125] In the curing process, the gypsum slurry can be cured. In the curing process, a cured gypsum slurry body can be obtained, which has a gypsum core 11 with cured gypsum slurry and a board base paper 12 disposed on a second main surface located at a position opposite to the first main surface of the gypsum core.

[0126] The curing process can be implemented by the solidification and setting of calcined gypsum (hemihydrate gypsum) contained in the gypsum raw material in the gypsum slurry through a hydration reaction, resulting in needle-like crystals of dihydrate gypsum. Therefore, in the gypsum slurry mold formed during the molding process, a reaction occurs between the calcined gypsum and water added to the gypsum raw material in the gypsum slurry, and the curing process can be implemented through the hydration reaction of the calcined gypsum.

[0127] (4) Coating layer formation process

[0128] In the coating layer forming process, a coating material can be applied to the side of the board base paper 12 located on the first main surface 11A of the gypsum core 11 opposite to the side facing the gypsum core 11 to form a coating layer 13.

[0129] The resins that can be used in coatings (coating liquids) have already been described as the resins contained in coating layer 13, so the description is omitted. In addition, when coating layer 13 is used after coating, as long as coating layer 13 contains the desired resin, the coating can also use resin precursors, etc.

[0130] If coating layer 13 contains a mildew inhibitor, the coating used in the coating layer forming process may also contain a mildew inhibitor. There are no particular limitations on the mildew inhibitor used in the coating; for example, the mildew inhibitors already described may be preferred.

[0131] In addition, in order to form a coating layer of the desired thickness while preventing dripping, various solvents can be added to the coating to adjust its viscosity.

[0132] There are no particular restrictions on the specific method for coating the base paper of the board; any method such as coil coating machine, flow coating machine, or spray coating can be used.

[0133] (5) Any process

[0134] The method for manufacturing gypsum board according to this embodiment can also include any steps. Specifically, for example, it can include one or more steps selected from the following steps: recess forming step, chamfering step, cutting step, and drying step.

[0135] (5-1) Recessed portion forming process

[0136] In the recess forming process, a recess can be formed on the first main surface 11A of the plaster core 11.

[0137] In the recess forming process, there is no particular limitation on the specific method of forming the recess, but for example, after the molding process or after the second cutting process, the recess can be formed by pressing a mold or the like onto the surface of the first main surface 11A of the plaster core 11 of the plaster slurry molded body.

[0138] In the recess formation process, it is preferable to form the recess with a force and depth that does not damage the board paper 12. The recess formation process can be performed, for example, before the coating layer formation process.

[0139] (5-2) Chamfering process

[0140] In the chamfering process, chamfering can be performed on the outer periphery of the surface 10A of the gypsum board 10, namely, the parts of edge 131, edge 132, edge 133, and edge 134.

[0141] There are no particular limitations on the method of chamfering, but the outer periphery of the surface 10A of the gypsum board 10 can be ground using a grinder or similar equipment to perform the chamfering. The chamfering process can be performed, for example, after the coating layer formation process.

[0142] (5-3) Cutting process

[0143] In the cutting process, a cutting device can be used to cut the gypsum slurry molded body.

[0144] After the plaster slurry is formed in the molding process, it gradually hardens in the curing process. Therefore, for example, the cutting process can be performed during or after the curing process. However, it is preferable to perform the cutting process after the curing process has progressed to a point where the plaster slurry can be cut.

[0145] The cutting process can be performed multiple times. Therefore, the method for manufacturing gypsum board according to this embodiment may include a first cutting process, which may be referred to as a rough cutting process. Additionally, a second cutting process may also be included.

[0146] In the first cutting process, the gypsum slurry molded body can be cut to the desired size according to, for example, the size of the dryer used in the drying process described later.

[0147] In addition, the second cutting process can be performed, for example, after the drying process, and can be cut into the desired product size.

[0148] (5-4) Drying process

[0149] In the drying process, the gypsum slurry molded body can be dried. During the drying process, any remaining moisture contained in the gypsum slurry molded body can be removed. Furthermore, it is preferable to supply the gypsum slurry molded body after the curing process has concluded during the drying process. The drying process can be implemented by forcibly drying the gypsum slurry molded body using a dryer.

[0150] The method of forcibly drying gypsum slurry molded bodies using a dryer is not particularly limited. For example, a dryer can be installed along the conveying path of the gypsum slurry molded bodies, allowing them to be continuously dried as they pass through the dryer. Alternatively, the gypsum slurry molded bodies can be moved into the dryer and dried in batches.

[0151] Example

[0152] The following are specific examples for illustration, but the present invention is not limited to these examples.

[0153] (1) Evaluation methods for the mildew resistance of gypsum board

[0154] The anti-mold performance is further evaluated by adding microbial strains in the test method B (determination of the inhibitory effect on mold growth) of plastic products described in Appendix A of JIS Z 2911 (2019) "Test methods for resistance to mold".

[0155] Specifically, gypsum board test pieces cut into 4cm squares were placed on a 5mm thick glucose-added inorganic salt medium. Then, the spore count for each mold species was adjusted to approximately 10. 6 Spray 1 mL of a mixed spore suspension of 1 spore / mL onto a gypsum board test piece.

[0156] The molds used in preparing the mixed spore suspension were prepared by adding Cladosporium (NBRC6348), Penicillium (NBRC100533), White mold (NBRC107725), Trichoderma (NBRC6355), and Chaetomium (NBRC6347) to the five specified species.

[0157] Plasterboard test pieces sprayed with a mixed spore suspension were cultured for mold growth every 4 weeks at a temperature of 29±1°C and a humidity of 95% RH or higher. After 4 weeks, the plasterboard test pieces were evaluated using a scale of 0 to 5 according to the following criteria. A score of 0 indicates the highest mold resistance, with the resistance decreasing as the number increases. A score of 0 or 1 indicates adequate mold resistance.

[0158] (Evaluation Criteria)

[0159] 0: No mold growth was observed with the naked eye or under a microscope.

[0160] 1: Mold growth is not visible to the naked eye, but it is visible under a microscope.

[0161] 2: The area of ​​mold coverage on the surface of the gypsum board test piece is less than 25%.

[0162] 3: The area of ​​mold-covered region on the surface of the gypsum board test piece is greater than 25% and less than 50%.

[0163] 4: The area of ​​mold coverage on the surface of the gypsum board test piece is more than 50% but less than 100%.

[0164] 5: The surface of the gypsum board test piece was completely covered with mold.

[0165] (2) Regarding the manufacturing conditions of the gypsum board in the experimental example

[0166] The manufacturing conditions for the gypsum board in each experimental example are described below. Experimental Examples 1 to 19 are exemplary cases, and Experimental Examples 20 to 39 are comparative examples.

[0167] [Experimental Example 1]

[0168] Plaster slurry is prepared by mixing calcined gypsum, water, a fungicide, and starch (plaster slurry preparation process). When the calcined gypsum is dihydrate gypsum, a fungicide is added to make its mass ratio relative to dihydrate gypsum 100 ppm.

[0169] The gypsum slurry is prepared by placing it between sheets of paper and forming it into a sheet shape to manufacture a gypsum slurry molded body (molding process).

[0170] Next, the obtained gypsum slurry molded body is cured (curing process).

[0171] After the curing process, gypsum board is manufactured by cutting the gypsum slurry into molded pieces and drying them (cutting process, drying process).

[0172] After the drying process, a coating made of a mixture of antifungal agent and acrylic resin is applied to the side of the board base paper 12 (first board base paper 121) located on the first main surface 11A of the gypsum core 11, opposite to the side facing the gypsum core 11, to form a coating layer (coating layer formation process). The coating is applied using a coating roller to achieve a coating thickness of 0.1 mm (approximately 100 g / m²). 2 When the gypsum core contains dihydrate gypsum, an antifungal agent is added to make the mass ratio relative to the dihydrate gypsum 20 ppm.

[0173] As shown in the "Type, Solubility, and Dosage of Antifungal Agent" column of Table 1, the antifungal agent used for gypsum core and coating layer is IMZ, with a solubility in water of 100 ppm or more. In Table 1, when the antifungal agent used for gypsum core has a solubility in water of 100 ppm or more, "O" is added to the "Solubility in Water" column.

[0174] The average coating thickness was measured and calculated in the obtained gypsum board, and the result confirmed that it was the same as the coating thickness of the coating layer, which was 0.1 mm. In other experimental examples, the average coating thickness was the same as the coating thickness of the coating layer.

[0175] Furthermore, since no waterproofing agent is added to the gypsum mortar, the proportion of waterproofing agent in the gypsum core 11 is 0. The same applies to Experimental Examples 2 to 32 below.

[0176] [Experimental Examples 2-8]

[0177] Except for changing the type of antifungal agent added to the plaster core and coating to the materials shown in Table 1, plasterboard was manufactured and evaluated under the same conditions as in Experimental Example 1. The evaluation results are shown in Table 1.

[0178] [Experimental Examples 9-12]

[0179] Except that the resin used for the coating was changed from acrylic resin to the resin shown in the "Coating Layer Resin" column of Table 1 and the coating layer was formed using this coating, gypsum board was manufactured and evaluated under the same conditions as in Experimental Example 2. The evaluation results are shown in Table 1.

[0180] [Experimental Example 13, Experimental Example 14]

[0181] When preparing the coating, if the calcined gypsum contained in the gypsum core is dihydrate gypsum, the antifungal agent is added at the mass ratio of the antifungal agent to the dihydrate gypsum as shown in the "Formulation Amount for Coating" column of Table 1. The coating is then used to form a coating layer. Otherwise, gypsum boards are manufactured and evaluated under the same conditions as in Experimental Example 2. The evaluation results are shown in Table 1.

[0182] [Experimental Example 15, Experimental Example 16]

[0183] When forming the coating layer, the coating thickness was set to the value shown in the "Coating Thickness" column of Table 1. Otherwise, gypsum board was manufactured and evaluated under the same conditions as in Experimental Example 2. The evaluation results are shown in Table 1.

[0184] [Experimental Examples 17-19]

[0185] The antifungal agents added to the gypsum core were the materials shown in Table 1. No antifungal agents were added to the coating layer. Otherwise, gypsum boards were manufactured and evaluated under the same conditions as in Experimental Example 1. The evaluation results are shown in Table 1.

[0186] [Experiment Example 20]

[0187] Except that no antifungal agent was added to the gypsum core and coating layer, gypsum boards were manufactured under the same conditions as in Experimental Example 1, and then evaluated. The evaluation results are shown in Table 1.

[0188] [Experimental Example 21, Experimental Example 22]

[0189] The antifungal agent added to the gypsum core was the material shown in Table 1. No coating layer was formed. Otherwise, gypsum boards were manufactured under the same conditions as in Experimental Example 1 and evaluated. The evaluation results are shown in Table 1.

[0190] [Experiment Example 23]

[0191] The gypsum board was manufactured under the same conditions as in Experimental Example 1, except that no antifungal agent was added to the coating layer, and the results were evaluated. The evaluation results are shown in Table 1.

[0192] [Experiment Example 24]

[0193] Except that the antifungal agents added to the gypsum core and coating layer were the materials shown in Table 1, gypsum boards were manufactured and evaluated under the same conditions as in Experimental Example 1. The evaluation results are shown in Table 1.

[0194] [Experimental Example 25, Experimental Example 26]

[0195] When preparing the coating, if the calcined gypsum contained in the gypsum core is dihydrate gypsum, the antifungal agent is added at a mass ratio to the dihydrate gypsum as shown in the "Formulation Amount for Coating" column of Table 1. Furthermore, the coating is used to form a coating layer, and gypsum board is manufactured and evaluated under the same conditions as in Experimental Example 24. The evaluation results are shown in Table 1.

[0196] [Experimental Example 27, Experimental Example 28]

[0197] When forming the coating layer, the coating thickness was set to the value shown in the "Coating Thickness" column of Table 1. Otherwise, gypsum board was manufactured and evaluated under the same conditions as in Experimental Example 24. The evaluation results are shown in Table 1.

[0198] [Experimental Examples 29~32]

[0199] Except that no antifungal agent was added to the gypsum core, and the antifungal agent added to the coating layer was the material shown in Table 1, gypsum boards were manufactured under the same conditions as in Experimental Example 1, and evaluated. The evaluation results are shown in Table 1.

[0200] [Experimental Examples 33~39]

[0201] Except that the antifungal agents added to the gypsum core and coating layer were the materials shown in Table 1, and a waterproofing agent was added to the gypsum core, gypsum boards were manufactured under the same conditions as in Experimental Example 1, and the results were evaluated. The evaluation results are shown in Table 1.

[0202] When using organopolysiloxane as a waterproofing agent, and when the gypsum contained in the gypsum core is considered to be dihydrate gypsum, the waterproofing agent is added in the proportion of 100 parts by weight of dihydrate gypsum as shown in the waterproofing agent column of Table 1.

[0203] [Table 1]

[0204] The results above confirm that the gypsum boards of Experimental Examples 1 to 19 have excellent anti-mildew properties. Specifically, by having a coating layer, the gypsum core 11 contains an anti-mildew agent with a solubility of 100 ppm or more relative to water, ensuring that the content of the waterproofing agent in the gypsum core is within the specified range, thereby improving the anti-mildew performance.

[0205] (Postscript)

[0206] (1) One aspect of this disclosure relates to a gypsum board having a gypsum core. The base paper for the board is disposed on the first main surface of the gypsum core and the second main surface opposite to the first main surface. A coating layer is applied to the surface of the board base paper located on the first main surface of the gypsum core, opposite to the surface opposite the gypsum core. The aforementioned gypsum core contains a mildew inhibitor with a solubility of over 100 ppm relative to water. The content of the waterproofing agent in the above-mentioned gypsum core is less than 0.1 parts by weight relative to 100 parts by weight of gypsum.

[0207] (2) In (1), the above coating layer may contain a mildew inhibitor.

[0208] (3) In (2), the above-mentioned gypsum core may contain at least one antifungal agent that is different from the antifungal agent contained in the coating layer.

[0209] (4) In any of (1) to (3), the average thickness of the coating layer can be more than 0.01 mm and less than 0.3 mm.

[0210] (5) In any of (1) to (4), the coating layer may contain resin.

[0211] (6) In any of (1) to (5), the first main surface of the plaster core may include a recess.

[0212] (7) In any of (1) to (6), it can be plasterboard for ceilings.

[0213] (8) One aspect of this disclosure relates to interior materials used for ceilings or walls, for dividing interior spaces, including gypsum board of any one of (1) to (7). The coating layer is located on the indoor side.

[0214] (9) One aspect of the present disclosure relates to a method for manufacturing gypsum board comprising the following steps: A gypsum slurry preparation process that involves mixing a mildew inhibitor with a solubility of more than 100 ppm relative to water, calcined gypsum, and water to prepare gypsum slurry. After the gypsum slurry is placed between the base paper sheets, the gypsum slurry is then formed into a sheet shape. A curing process for obtaining a cured gypsum slurry body having a gypsum core formed by curing the gypsum slurry and the board base paper disposed on a first main surface of the gypsum core and a second main surface opposite to the first main surface. A coating layer forming process involves applying a coating material to the surface of the board base paper located on the first main surface of the gypsum core, opposite to the surface opposite the gypsum core, to form a coating layer. The content of the waterproofing agent in the gypsum core is less than 0.1 parts by weight relative to 100 parts by weight of gypsum.

[0215] The above description of gypsum board, interior decoration materials, and methods for manufacturing gypsum board has been provided through various embodiments, but the present invention is not limited to the embodiments described above. Various modifications and alterations can be made within the scope of the spirit of the invention as set forth in the claims.

[0216] This application claims priority based on Japan Patent Application No. 2024-046736, filed with the Japan Patent Office on March 22, 2024, and the entire contents of Japan Patent Application No. 2024-046736 are incorporated in this international application.

[0217] [Explanation of Symbols]

[0218] 10: Plasterboard.

[0219] 10A: Surface.

[0220] 10B: Back side.

[0221] 11: Plaster core.

[0222] 11A: First primary surface.

[0223] 11B: Second primary surface.

[0224] 12: The base paper for the board.

[0225] 121: The first board uses the original paper.

[0226] 122: The second board uses the original paper.

[0227] 121A: Page 1.

[0228] 121B: Page 2.

[0229] 13: Coating layer.

[0230] 131: Side.

[0231] 132: Side.

[0232] 133: Side.

[0233] 134: Side.

[0234] T13: Thickness.

[0235] 31: concave part.

[0236] 31A: Bottom surface.

[0237] 31B: Side view.

[0238] 32: Convex part.

[0239] 40: Interior materials.

[0240] 41: Edge.

Claims

1. A type of gypsum board, wherein, It has the following characteristics: Plaster core, The base paper for the board is disposed on the first main surface of the gypsum core and on the second main surface opposite to the first main surface, and A coating layer disposed on the surface of the board base paper opposite to the surface opposite to the gypsum core, located on the first main surface of the gypsum core. The gypsum core contains a mildew inhibitor with a solubility of more than 100 ppm relative to water. In the gypsum core, the content of waterproofing agent is less than 0.1 parts by weight relative to 100 parts by weight of gypsum.

2. The gypsum board according to claim 1, wherein, The coating layer contains an antifungal agent.

3. The gypsum board according to claim 2, wherein, The gypsum core contains at least one antifungal agent that is different from the antifungal agent contained in the coating layer.

4. The gypsum board according to any one of claims 1 to 3, wherein, The average thickness of the coating layer is between 0.01 mm and 0.3 mm.

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

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

7. The gypsum board according to any one of claims 1 to 3, wherein, It is plasterboard used for ceilings.

8. An interior material, wherein, It is an interior decoration material used for ceilings or walls to divide interior spaces, comprising gypsum board as described in any one of claims 1 to 3. The coating layer is located on the indoor side.

9. A method for manufacturing gypsum board, wherein, It has the following characteristics: The process of preparing gypsum slurry involves mixing a mildew inhibitor with a solubility of more than 100 ppm relative to water, calcined gypsum, and water. After the gypsum slurry is placed between the base paper sheets, the gypsum slurry is then subjected to a molding process to form a sheet. A curing process for obtaining a cured gypsum slurry body having a gypsum core formed by curing the gypsum slurry, and the board base paper disposed on a first main surface of the gypsum core and a second main surface opposite to the first main surface, and a curing process for obtaining a cured gypsum slurry body having the gypsum core having cured gypsum slurry, and the board base paper having cured gypsum slurry, and a second main surface disposed on the first main surface of the gypsum core having cured gypsum slurry, and a second main surface disposed on the opposite side of the first main surface of the gypsum core having cured gypsum slurry, and a second main surface disposed on ... opposite side of the first main surface of the gypsum slurry, and a third main surface disposed on the first main surface of the gypsum A coating layer forming process is performed on the surface of the board base paper located on the first main surface of the gypsum core, opposite to the surface opposite the gypsum core, by applying a coating material to form a coating layer. In the gypsum core, the content of waterproofing agent is less than 0.1 parts by weight relative to 100 parts by weight of gypsum.

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