Production method of gypsum board

Abstract

To provide a production method of a gypsum board capable of producing a high density gypsum board.SOLUTION: A production method of a gypsum board is provided with: a stirring process stirring a mixture 2 including 100 pts. mass of hemihydrate gypsum and 20 to 40 pts. mass of water; an adding process adding in the layer state the mixture 2 processed in the stirring process on a lower side base paper 1 placed to cover a lower mold 30 of a press mold 10 having an upper mold 20 and the lower mold 30; a pressure application molding process applying pressure on a layer 4 obtained by stacking an upper side base paper 3 on an upper surface of the mixture 2 in the layer state while sandwiching it between the lower mold 30 and the upper mold 20; and a drying process drying the layer 4 after the pressure application molding process.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a gypsum board. [Background technology]

[0002] Gypsum boards are plate-shaped components whose main component is gypsum, and are excellent in fire resistance, sound insulation, ease of installation, etc. Therefore, this type of gypsum board is widely used as a building material for constructing walls, ceilings, etc.

[0003] Known gypsum boards include, for example, those having a plate-shaped core material whose main component is gypsum and base paper laminated on both sides of the core material (so-called gypsum boards). As shown in Patent Document 1, for example, this gypsum board is obtained by pouring a slurry consisting of a mixture of calcined gypsum (hemihydrate gypsum) and water between a lower base paper flowing on a belt conveyor and an upper base paper flowing parallel to the lower base paper, and drying the laminate.

[0004] When preparing the slurry, it is necessary to use about 3.5 to 4.5 times the theoretical amount of water required for hydrating the hemihydrate gypsum in order to ensure sufficient fluidity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-71218 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, conventional methods for manufacturing gypsum boards use slurries with a high water content, which results in low bulk densities of the resulting gypsum boards (for example, about 0.95 to 1.15). As a result, the gypsum boards obtained by these conventional manufacturing methods tend to have low strength and low durability.

[0007] Therefore, for example, when an attempt is made to prepare a slurry by adding a small amount of water to gypsum hemihydrate in order to manufacture a gypsum board with a high bulk density, the mixture of gypsum hemihydrate and water becomes lumpy (like a lump or a dumpling). Such a slurry cannot be stirred and mixed uniformly, and because it lacks fluidity, it cannot be poured between the upper and lower base papers when manufacturing a gypsum board.

[0008] Due to these circumstances, a new method for manufacturing gypsum boards that can produce high-density gypsum boards has been desired.

[0009] An object of the present invention is to provide a method for manufacturing a gypsum board that can produce a high-density gypsum board. [Means for solving the problem]

[0010] <1> A method for manufacturing a gypsum board, comprising: a stirring step of stirring a mixture containing 100 parts by mass of gypsum hemihydrate and 20 to 40 parts by mass of water; an application step of applying the mixture after the stirring step in the form of a layer on a lower base paper laid so as to cover the lower mold of a press mold having an upper mold and a lower mold; a pressure molding step of sandwiching and pressing a laminate obtained by placing the upper base paper on the top surface of the layered mixture between the lower mold and the upper mold; and a drying step of drying the laminate after the pressure molding step.

[0011] <2> In the stirring step, a stirrer equipped with a chopper is used, and the mixture is stirred at high speed under the condition of a rotation speed of the chopper of 3000 to 6000 rpm. <1> The method for manufacturing a gypsum board according to claim 1.

[0012] <3> In the application step, the lower mold has at least a bottom and a set of peripheral wall portions arranged on the periphery of the bottom so as to face each other with the bottom portion interposed therebetween, and the lower base paper has at least a lower base paper for the bottom placed on the bottom and a set of lower peripheral wall base papers each connected to the periphery of the lower base paper and overlapped on the set of peripheral wall portions, and the mixture after the stirring step is applied in a layer on the lower base paper for the bottom, and both side surfaces of the layered mixture are covered with the set of lower peripheral wall base papers. <1> or <2> The method for manufacturing a gypsum board according to claim 1.

[0013] <4> In the pressure molding step, the upper mold presses the laminate between the pair of peripheral wall portions and the bottom portion while sandwiching the laminate between the upper mold and the pair of peripheral wall portions. <3> The method for manufacturing a gypsum board according to claim 1.

[0014] <5> In the pressure molding process, when the laminate is pressurized between the lower mold and the upper mold, the liquid squeezed out from the layered mixture permeates into the lower base paper and the upper base paper, respectively. In the drying process, the laminate in which the liquid has permeated into the lower base paper and the upper base paper, respectively, is dried, thereby obtaining a gypsum board in which the lower base paper and the upper base paper are bonded to a core material made of a dried product of the mixture. <1> or <2> The method for manufacturing a gypsum board according to claim 1. [Effects of the Invention]

[0015] According to the present invention, a method for manufacturing a gypsum board capable of manufacturing a high-density gypsum board can be provided. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram schematically illustrating a press mold used in a method for producing a gypsum board according to embodiment 1. [Figure 2] An explanatory diagram showing the application process [Figure 3] An explanatory diagram showing the state in which the laminate obtained by placing the upper base paper on the top surface of the layered mixture is contained in the lower mold. [Figure 4]Schematic diagram of the pressure molding process [Figure 5] A schematic diagram of the press mold opened after the pressure molding process. [Figure 6] FIG. 1 is an explanatory diagram schematically illustrating the configuration of a gypsum board manufactured by the gypsum board manufacturing method of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Embodiment 1> A method for manufacturing a gypsum board according to a first embodiment of the present invention will be described below with reference to Fig. 1 to Fig. 6. The method for manufacturing a gypsum board according to this embodiment includes a stirring step, an applying step, a pressure molding step, and a drying step.

[0018] (stirring process) The stirring step is a step of stirring a mixture containing 100 parts by mass of gypsum hemihydrate and 20 to 40 parts by mass of water. In the present embodiment, a small amount of water is used relative to the amount of gypsum hemihydrate, and therefore, the gypsum hemihydrate and water are stirred in the ratio described above.

[0019] Gypsum hemihydrate (CaSO 1 / 2H O) is also called calcined gypsum. There are no particular limitations on the type of gypsum hemihydrate as long as it does not impair the object of the present invention, but examples that can be used include natural gypsum, chemical gypsum, and β-type gypsum hemihydrate produced from waste gypsum.

[0020] The mixture of this embodiment containing gypsum hemihydrate and water is not in a slurry state but in a semi-dry state, and is composed of a mass of wet, bulky powder.

[0021] In the stirring step, the mixture is mixed and stirred using a high-speed stirring mixer with high shear force. Specifically, when adding a small amount of liquid, it is preferable to use a stirrer (one example of a high-speed stirring mixer) equipped with a chopper to break down lumps and clumps. This stirrer stirs the mixture at high speed with the chopper rotating at a speed of 3000 to 6000 rpm. In the stirring step, the action of the chopper rotating at high speed stirs the mixture so that the hemihydrate gypsum and water are uniformly mixed and dispersed, preventing the mixture from becoming lumpy (so-called clumps or ball-like).

[0022] In addition to the hemihydrate gypsum and water, various known additives such as an adhesion promoter (oxidized starch, polyvinyl alcohol, etc.), a hardening accelerator, a hardening retarder, inorganic fibers, organic fibers, a water repellent, a resin, and a mildew inhibitor may be added to the mixture as needed, as long as the object of the present invention is not impaired.

[0023] (Application process) Fig. 1 is an explanatory diagram schematically showing a press die 10 used in the method for producing a gypsum board according to embodiment 1, and Fig. 2 is an explanatory diagram schematically showing the application step. The application step is a step of applying a layer of the mixture 2 after the stirring step onto a lower base paper 1 laid so as to cover a lower die 30 of the press die 10 having an upper die 20 and a lower die 30.

[0024] The press die 10 has a lower die 30 disposed below and an upper die 20 disposed above the lower die 20 and movable in the vertical direction. The lower die 30 has a bottom 31 and a pair of peripheral wall portions 32 and 33 disposed on the periphery of the bottom 31 so as to face each other with the bottom 31 interposed therebetween.

[0025] The bottom 31 has a flat mounting surface 31a that is rectangular in plan view. Lower bottom base paper 1a of the lower base paper 1 is laid to cover this mounting surface 31a. FIG. 1 shows the state in which the lower base paper 1 used to manufacture a gypsum board is placed (set) in a predetermined position of the press mold 10. The lower base paper 1 has a lower bottom base paper 1a that is rectangular in plan view and a set of lower peripheral wall base papers 1b, 1c connected to its periphery. The lower peripheral wall base papers 1b, 1c are arranged parallel to each other with the lower bottom base paper 1a between them. The lower base paper 1 has another set of lower peripheral wall base papers (not shown).

[0026] The pair of peripheral wall portions 32, 33 are arranged parallel to each other and facing each other with the bottom portion 31 therebetween. The pair of peripheral wall portions 32, 33 are arranged on the periphery of the bottom portion 31 so that their height positions from the placement surface 31a are the same.

[0027] In FIG. 1, one of the lower peripheral wall base papers 1b provided on the lower base paper 1 is placed on the wall surface 32a of one peripheral wall portion 32 shown on the left side, facing the opposing peripheral wall portion 33. In addition, in FIG. 1, the other of the lower peripheral wall base papers 1c provided on the lower base paper 1 is placed on the wall surface 33a of the other peripheral wall portion 33 shown on the right side, facing the opposing peripheral wall portion 32. Each of the lower peripheral wall base papers 1b, 1c is set to a size that can completely cover each wall surface 32a, 33a. Note that the size of each of the lower peripheral wall base papers 1b, 1c of the lower base paper 1 used in manufacturing the gypsum board is set to be larger (for example, about twice the size) than the size of the portion that will ultimately remain as part of the gypsum board.

[0028] In addition to the bottom 31 and the pair of peripheral walls 32, 33, the lower mold 30 also has another pair of peripheral walls (not shown). This pair of peripheral walls is arranged on the periphery of the bottom 31, facing each other with the bottom 31 between them, on the front and back sides of the paper in FIG. 1 etc. These two pairs of peripheral walls surround the bottom 31 in a frame-like manner. In other words, the bottom 31 and the peripheral walls 32, 33, etc. form the overall shape of the lower mold 30 in the form of a container that is open upward.

[0029] The upper mold 20 is configured to be movable up and down by a known reciprocating mechanism. The upper mold 20 has an opposing surface 20a that faces the mounting surface 31a of the bottom 31 of the lower mold 30. The opposing surface 20a has a rectangular shape in a plan view.

[0030] As shown in FIG. 2, the mixture 2 after the above-described stirring process is applied in a layer on the lower base paper 1 laid so as to cover the lower mold 30 of the press mold 10. More specifically, as shown in FIG. 2, the mixture 2 after the stirring process is applied in a layer on the lower bottom base paper 1a, and both side surfaces 2b, 2c of the layered mixture 2 are covered with a pair of lower peripheral wall base papers 1b, 1c. At this time, one side surface 2b of the layered mixture 2 shown on the left side of FIG. 2 is covered with one lower peripheral wall base paper 1b, and the other side surface 2c of the layered mixture 2 shown on the right side of FIG. 2 is covered with the other lower peripheral wall base paper 1c. The lower surface 2a of the layered mixture 2 is in contact with the lower bottom base paper 1a laid on the bottom 31 (mounting surface 31a) of the lower mold 30.

[0031] The lower base paper 1 set in the lower mold 30 is placed on the placing surface 31a of the bottom 31 in the shape of a container with an open top, with the lower peripheral wall base paper 1b, 1c, etc. rising from the periphery of the lower bottom base paper 1a. The mixture 2 is placed on the bottom 31 (placing surface 31a) of the lower mold 30 so as to be contained in the container-shaped lower base paper 1. The mixture 2 is placed on the bottom 31 (placing surface 31a) so as not to exceed the height (height from the placing surface 31a) of the peripheral wall portions 32, 33. The mixture 2 is formed in a layer on the lower bottom base paper 1a so as not to exceed the height (length) of the lower peripheral wall base paper 1b, 1c. In the lower mold 30, it is preferable that the mixture 2 be placed on the placing surface 31a of the bottom 31 via the lower bottom base paper 1a so as to have a substantially uniform thickness.

[0032] The lower base paper 1 and the upper base paper 3 (described later, see FIG. 3, etc.) are made of the same material as base paper used in the industry (for example, corrugated cardboard, thick paper). The type of base paper material, thickness, and other conditions are set appropriately depending on the purpose.

[0033] (Pressure molding process) The pressure molding process is a process in which a laminate 4 obtained by placing an upper base paper 3 on the upper surface 2d of a layered mixture 2 is sandwiched and pressed between the lower mold 30 and the upper mold 20. FIG. 3 is an explanatory diagram showing a state in which the laminate 4 obtained by placing the upper base paper 3 on the upper surface 2d of the layered mixture 2 is accommodated in the lower mold 30. After the laminate 4 is formed in this manner, as shown in FIG. 4, the upper mold 20 is lowered and the pressure molding process is carried out. FIG. 4 is an explanatory diagram that schematically shows the pressure molding process. As shown in FIG. 4, in the pressure molding process, the upper mold 20 is lowered and the laminate 4 is sandwiched between the lower mold 30 and the upper mold 20. The upper mold 20 is sized to fit between the peripheral walls 32 and 33 of the lower mold 30, and while positioned between the peripheral walls 32 and 33, the laminate 4 is sandwiched between the bottom 31 of the lower mold 30.

[0034] When the laminate 4 is sandwiched between the upper mold 20 and the lower mold 30 and pressurized in this manner, the layered mixture 2 is compressed, reducing the thickness of the laminate 4. When pressurized, the liquid squeezed out of the mixture 2 (a liquid in which gypsum hemihydrate is dissolved in water) permeates the lower base paper 1 and the upper base paper 3. By the liquid containing gypsum hemihydrate permeating the lower base paper 1 and the upper base paper 3 in this manner, adhesion between the core material of the gypsum board that is finally obtained and the base papers (lower base paper 1, upper base paper 3) is ensured.

[0035] The molding pressure applied by the press die 10 is not particularly limited as long as it does not impair the object of the present invention. For example, it is 9 kgf / cm 2 More than 200kgf / cm 2 Less than (preferably 20 kgf / cm 2 More than 200kgf / cm 2When the molding pressure is in this range, adhesion between the core material of the gypsum board and the base paper is ensured.

[0036] After the pressure molding process, the upper die 20 is raised to its initial standby position, and the press die 10 is opened. FIG. 5 is an explanatory diagram schematically illustrating the state of the press die 10 after the pressure molding process. In this embodiment, when the press die 10 is opened, the bottom 31 of the lower die 30 can be raised so that the height position of the mounting surface 31a is the same as the height position of the upper end surfaces of the peripheral wall portions 32, 33. By configuring the lower die 30 in this manner, the laminate 4 after the pressure molding process can be easily removed from the press die 10. Note that after the laminate 4 is removed from the press die 10, the bottom 31 of the lower die 30 descends to the initial position shown in FIG. 1, etc.

[0037] (drying process) The drying step is a step of drying the laminate 4 after the pressure molding step. This drying step can be performed using equipment similar to that used in the drying step of general gypsum boards (plaster boards, etc.). The laminate 4 is placed in a drying device set at 60 to 200°C, for example, and heated for a predetermined time.

[0038] After the drying step, unnecessary portions of the bottom base paper 1 (parts of the lower peripheral wall base papers 1b, 1c) of the laminate 4 may be appropriately cut off. In another embodiment, unnecessary portions of the bottom base paper 1 (parts of the lower peripheral wall base papers 1b, 1c) may be cut off in advance before the drying step.

[0039] The gypsum board 6 of this embodiment is manufactured through the above-mentioned steps. Fig. 6 is an explanatory diagram schematically showing the configuration of the gypsum board 6 manufactured by the gypsum board manufacturing method of this embodiment. According to the gypsum board manufacturing method of this embodiment, a high-density gypsum board 6 can be easily manufactured.

[0040] Here, a gypsum board 6 manufactured by the manufacturing method of this embodiment will be described with reference to Fig. 6. Fig. 6 schematically shows a cross-sectional configuration of the gypsum board 6 cut in the short direction. The gypsum board 6 is made of a plate-shaped core material 5, and a lower base paper 1 and an upper base paper 3 that cover the surface of the core material 5.

[0041] The core material 5 is made of the hardened mixture 2 containing the above-mentioned gypsum hemihydrate (CaSO4·1 / 2H2O) and water. The core material 5 is a plate-shaped (board-shaped) member containing gypsum (gypsum component) mainly consisting of gypsum dihydrate (CaSO4·2H2O).

[0042] As described above, the lower base paper 1 and the upper base paper 3 are made of the same material as base paper used in the industry (for example, corrugated cardboard, thick paper).

[0043] The core material 5 of the gypsum board 6 manufactured by the gypsum board manufacturing method of this embodiment can have a higher bulk density than that manufactured by a conventional manufacturing method using a slurry. In this embodiment, the bulk density of the core material 5 of the gypsum board 6 can be set to, for example, 1.3 kg / cm 3 ~2.0kg / cm 3 In the conventional method for manufacturing gypsum boards using a slurry, the bulk density of the core material can be reduced to about 1.3 g / cm. 3 That was about it.

[0044] According to the method for manufacturing a gypsum board of this embodiment, it is possible to manufacture a gypsum board (gypsum board, reinforced gypsum board, hard gypsum board, fiber-mixed gypsum board, etc.) having a high bulk density.

[0045] The gypsum board of this embodiment is excellent in dimensional stability, impact resistance, strength, screwing ability, etc. Furthermore, the gypsum board of this embodiment is also excellent in fire resistance, sound insulation, workability, economy, etc. According to the manufacturing method of the gypsum board of this embodiment, the cost of the drying process is low because the amount of water evaporated in the drying process is small. Furthermore, the gypsum board of this embodiment has a stable cut surface that is not easily broken when cut.

[0046] Furthermore, according to the method for manufacturing a gypsum board of this embodiment, the formation of voids caused by the escape of excess water during drying is suppressed, so the inside of the gypsum board (core material) has a uniform composition.

[0047] The gypsum board manufactured by the gypsum board manufacturing method of the present embodiment can be used in locations requiring strength, such as interior walls, partition walls, ceilings, pillars, etc. Examples of buildings include music halls, lobbies, hospitals, schools, halls, stores, accommodation facilities, gymnasiums, and underground walkways.

[0048] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples in any way.

[0049] [Examples 1 to 5 and Comparative Example 1] (Making gypsum boards) 100 parts by mass of hemihydrate gypsum (calcined gypsum) and ○ parts by mass of water were mixed and stirred using a high-speed stirring mixer to obtain a semi-dry mixture. The obtained mixture was then pressed using the press mold 10 at a molding pressure (kgf / cm) shown in Table 1 in the same manner as in the first embodiment. 2 The gypsum boards were prepared under the conditions of (1) and (2). The lower and upper base papers used were base papers (cardboard base paper manufactured by Hyogo Paper Co., Ltd.) having a thickness of approximately 0.2 mm.

[0050] (bulk density) The bulk density of the core material of each of the obtained gypsum boards was measured, and the results are shown in Table 1.

[0051] (Adhesion between core material and base paper) The adhesion between the core seat and base paper of each of the obtained gypsum boards was confirmed by the method described below. The results are shown in Table 1. In Table 1, cases where there was adhesion are indicated by "○", and cases where there was no adhesion (or insufficient adhesion) are indicated by "×".

[0052] [Table 1]

[0053] As shown in Table 1, the molding pressure was 9 kgf / cm 2 It was confirmed that the above conditions make it possible to produce a gypsum board having a high bulk density and excellent adhesion between the core material and atoms.

[0054] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0055] (1) In the above-mentioned embodiment 1, when the press mold is opened, the bottom is configured to rise so that the height position of the mounting surface and the height position of each upper end face of the peripheral wall portion are at the same height position. However, the present invention is not limited to this, and in other embodiments, when the mold is opened, the peripheral wall portion may be lowered so that the height position of the mounting surface and the height position of each upper end face of the peripheral wall portion are at the same height position. [Explanation of symbols]

[0056] 1...lower base paper, 2...mixture, 3...upper base paper, 4...laminate, 5...core material, 6...gypsum board, 10...press mold, 20...upper mold, 30...lower mold,

Claims

1. a stirring step of stirring a mixture containing 100 parts by mass of hemihydrate gypsum and 20 to 40 parts by mass of water; an application step of applying the mixture after the stirring step in the form of a layer onto a lower base paper placed so as to cover a lower mold of a press mold having an upper mold and a lower mold; a pressure molding step of sandwiching and pressing a laminate obtained by placing an upper base paper on an upper surface of the layered mixture between the lower mold and the upper mold; A method for manufacturing a gypsum board, comprising: a drying step of drying the laminate after the pressure molding step.

2. The method for manufacturing a gypsum board according to claim 1, wherein in the stirring step, a stirrer equipped with a chopper is used and the mixture is stirred at high speed under conditions of a rotation speed of the chopper of 3000 to 6000 rpm.

3. In the applying step, the lower mold has at least a bottom portion and a pair of peripheral wall portions disposed on the periphery of the bottom portion so as to face each other with the bottom portion interposed therebetween; The lower base paper includes at least a lower bottom base paper laid on the bottom portion, and a set of lower peripheral wall base papers each connected to the peripheral edge of the lower bottom base paper and overlapped on a set of peripheral wall portions, 3. The method for manufacturing a gypsum board according to claim 1 or 2, wherein the mixture after the stirring step is applied in a layer on the lower bottom base paper, and both side surfaces of the layered mixture are covered with a set of lower peripheral wall base papers.

4. The method for manufacturing a gypsum board according to claim 3, wherein in the pressure molding step, the upper mold pressurizes the laminate while sandwiching it between the set of peripheral wall portions and the bottom portion.

5. In the pressure molding step, when the laminate is pressed between the lower mold and the upper mold, liquid squeezed out from the layered mixture permeates into the lower base paper and the upper base paper, respectively; 3. The method for manufacturing a gypsum board according to claim 1 or 2, wherein in the drying step, the laminate in which the liquid has permeated the lower base paper and the upper base paper, respectively, is dried to obtain a gypsum board in which the lower base paper and the upper base paper are each adhered to a core material made of a dried product of the mixture.

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