Production method and production system of water-resistant gypsum board

Abstract

The invention relates to the technical field of gypsum board production, and discloses a waterproof gypsum board production method, which comprises: sequentially adding calcined gypsum powder, a water reducing agent, PVAC, silicone oil, a basic catalyst and starch into water, standing, and uniformly stirring after standing to obtain a gypsum slurry; in the stirring process, the gypsum slurry is poured into first surface protection paper and then covered with second surface protection paper, a pressing plate and a ballasting object are adopted to be arranged on the second surface protection paper in a pressing mode, the gypsum slurry is shaped into a plate body till the plate body is finally set, the pressing plate is removed, and a wet plate is obtained; and carrying out distributed drying on the wet board to obtain the water-resistant gypsum board. The invention further discloses a production system of the water-resistant gypsum board. Double waterproof performance protection of the plasterboard body and the surface protection paper is achieved, an assembly line production device is provided, a pressing plate or a ballasting object does not need to be moved, and time and labor are saved.

Description

Technical Field

[0001] The present invention relates to the technical field of gypsum board production, and particularly relates to a production method and a production system for water-resistant gypsum boards. Background Art

[0002] Water-resistant paper-faced gypsum board uses building gypsum as the main raw material, and a certain amount of waterproofing agent and surfactant and other additives are added to the gypsum core material to endow the gypsum itself with certain waterproof performance.

[0003] Currently, the production process of water-resistant gypsum board is mainly to add raw materials such as silicone oil, alkaline catalyst, calcined gypsum powder, and water into a mixer for mixing. In actual production, due to the defoaming effect of waterproofing agents such as silicone oil, if the addition amount of silicone oil is too much or the mixing of silicone oil is uneven, it may lead to unqualified water absorption rate and surface water absorption of the produced water-resistant gypsum board.

[0004] At the same time, part of the support strength of the gypsum board is provided by the facing paper. If the surface water absorption of the gypsum board is high, the connection effect between the gypsum board core and the facing paper will decline, resulting in gaps between the gypsum board core and the facing paper. If there is moisture and oxygen in the gaps to generate mold, the gas generated by the mold will further expand the gaps, and over time, it will lead to the detachment of the facing paper, greatly reducing the service life of the gypsum board body. Summary of the Invention

[0005] The purpose of the present invention is to provide a production method and a production system for water-resistant gypsum boards to solve the technical problem of high surface water absorption of gypsum boards in the prior art.

[0006] To solve the above technical problems, the present invention specifically provides the following technical solutions:

[0007] The present invention provides a production method for water-resistant gypsum boards, including the following steps:

[0008] Add calcined gypsum powder, water reducing agent, PVAC, silicone oil, alkaline catalyst, and starch into water in sequence, let it stand, and stir until uniform after standing to obtain gypsum slurry;

[0009] During the stirring process, pour the gypsum slurry into the first facing paper, then cover it with the second facing paper, use a pressing plate and a pressing weight to press on the second facing paper, shape the gypsum slurry into a plate body until the plate body finally sets, and remove the pressing plate to obtain a wet plate;

[0010] Perform distributed drying on the wet plate to obtain the water-resistant gypsum board.

[0011] As a preferred embodiment of the present invention, the formulation of the water-resistant gypsum board is as follows, by mass: 1000 parts of calcined gypsum powder, 3.6 parts of water reducer, 2 parts of PVAC, 1.8 parts of silicone oil, 0.3 - 1.2 parts of alkaline catalyst, 6 parts of starch, and 530 parts of water.

[0012] As a preferred embodiment of the present invention, the calcined gypsum powder is the gypsum powder after two-step calcination and aging;

[0013] The water reducer is a naphthalene-based water reducer;

[0014] The alkaline catalyst is ordinary 42.5 Portland cement.

[0015] As a preferred embodiment of the present invention, the step-by-step drying includes the following steps: internally drying the wet board at a temperature of 160 ± 2 °C for 30 min, and then drying it at a temperature of 45 ± 2 °C for 24 h and then taking it out.

[0016] The present invention provides a production system for water-resistant gypsum boards, including a mixer, a conveyor belt, and a drying device. The mixer extrudes the mixed gypsum slurry into the conveyor belt. The conveyor belt can transport the gypsum slurry away from the mixer until the gypsum slurry finally sets into a wet board. The drying device is used to dry the wet board;

[0017] An inlet is provided at the end of the conveyor belt close to the mixer, and an outlet is provided at the end of the conveyor belt close to the drying device. The inlet allows the first facing paper and the second facing paper to pass through. The mixer can continuously pour the stirred gypsum slurry from the inlet onto the first facing paper. The gypsum slurry forms a board between the first facing paper and the second facing paper and finally sets into the wet board at the outlet;

[0018] Fixing plates are provided at both ends of the conveyor belt. A pressing plate is slidably provided on the fixing plates. The pressing plate can move above the second facing paper. A pressing weight is provided on the pressing plate. The pressing plate and the pressing weight can shape the gypsum slurry located between the first facing paper and the second facing paper during the movement of the first facing paper.

[0019] As a preferred embodiment of the present invention, on the inlet, a first baffle is provided between the two fixing plates. At the outlet, a second baffle parallel to the first baffle is also provided. The pressing plate is arranged between the first baffle and the second baffle. The first baffle and the second baffle limit the pressing plate in the horizontal direction.

[0020] As a preferred embodiment of the present invention, the bottom of the first baffle is bent into an arc towards the pressing plate, and the arc-shaped side of the first baffle is butted against the pressing plate, and the second facing paper can be attached to the arc-shaped side of the first baffle.

[0021] As a preferred embodiment of the present invention, a peripheral edge is provided on the periphery of the pressing plate, and the peripheral edge encloses the top of the pressing plate into a groove body, and the pressing weight is arranged in the groove body.

[0022] As a preferred embodiment of the present invention, the pressing weight includes a plurality of density boards stacked together, and the periphery of the board body is attached to the peripheral edge, and each density board has a uniform density and thickness.

[0023] As a preferred embodiment of the present invention, a notch is provided on the peripheral edge, and the notch extends downward to the pressing plate, and the notch is used to expose the density board.

[0024] The present invention has the following beneficial effects compared with the prior art:

[0025] The present invention uses polyvinyl acetate as an additive for the gypsum board, which can protect the double waterproof performance of the gypsum board body and the facing paper. One is that it can be used as an adhesive to improve the bonding effect between the gypsum board surface and the facing paper, and prevent moisture from entering the gypsum board core through the gap between the facing paper and the gypsum board core; at the same time, polyvinyl acetate hydrolyzes into polyvinyl alcohol in an alkaline solvent, which can significantly improve the water resistance of the paper, so that the paper can still maintain good performance in a humid environment, thereby further reducing the surface water absorption rate of the gypsum board.

[0026] The present invention further provides an assembly line production system. By pulling the formed gypsum board, the unformed gypsum board slurry and the facing paper directly enter the pressing environment, and solidification is completed during the pressing and forming process. The production efficiency is high, and there is no need to move the pressing plate or the pressing weight, which saves time and effort. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can be obtained according to the provided drawings.

[0028] Figure 1 It is a schematic flow chart of the production method of the water-resistant gypsum board provided by the present invention;

[0029] Figure 2Schematic structural diagram of the production system for water-resistant gypsum boards provided by the present invention;

[0030] Figure 3 Provided by the present invention Figure 2 Schematic structural diagram of the conveyor belt in the illustrated embodiment;

[0031] Figure 4 Provided by the present invention Figure 2 Schematic structural diagram of the weight in the illustrated embodiment;

[0032] Figure 5 Provided by the present invention Figure 2 Schematic structural diagram of the pressing plate in the illustrated embodiment.

[0033] The reference numerals in the figure respectively represent the following:

[0034] 1 - Mixer; 2 - Conveyor belt; 3 - Drying device; 4 - Paper inlet; 5 - Plate outlet; 6 - Fixed plate; 7 - Pressing plate; 8 - Weight; 9 - First baffle; 10 - Second baffle; 11 - Perimeter; 12 - Notch. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] As Figure 1 shown, the present invention provides a production method for water-resistant gypsum boards, including the following steps:

[0037] Add plaster of Paris powder, water reducing agent, PVAC, silicone oil, alkaline catalyst, and starch into water in sequence, and let it stand for a while (the plaster of Paris powder and starch are completely immersed in water to prevent dust from floating during stirring). After standing, stir until uniform (the stirring time is 1 - 2 min) to obtain gypsum slurry;

[0038] During the stirring process, pour the gypsum slurry into the first facing paper, then cover it with the second facing paper, press it on the second facing paper with a pressing plate and a weight, and shape the gypsum slurry into a plate body until the plate body finally sets. Then remove the weight and the pressing plate in sequence to obtain a wet plate;

[0039] Bake the wet plate in an internal oven at a temperature of 160 ± 2 °C for 30 min, then bake it at a temperature of 45 ± 2 °C for 24 h and take it out, and remove the pressing plate to obtain the water-resistant gypsum board.

[0040] Among them, polyvinyl acetate (PVAc) can be used as an adhesive to improve the adhesion effect between the gypsum board surface and the facing paper, preventing moisture from entering the gypsum board core through the gap between the facing paper and the gypsum board core. Secondly, PVAC can improve the toughness and water resistance of the facing paper, prevent moisture from seeping into the gypsum board core from the facing paper, and improve the overall surface water absorption resistance of the gypsum board.

[0041] Furthermore, polyvinyl acetate is easily hydrolyzed into polyvinyl alcohol in an alkaline solvent. Polyvinyl alcohol has good film-forming properties and can significantly improve the water resistance of paper, which enables the paper to maintain good performance in a humid environment, thereby further reducing the surface water absorption rate of the gypsum board.

[0042] The above principle is similar to that found in the production of fiberglass mat boards in factories, where the water absorption rate can be effectively reduced under the action of residual emulsion. In the present invention, through polyvinyl acetate and polyvinyl alcohol generated under alkaline action, not only can the waterproof performance of the board core be improved together with silicone oil, but also it can adhere between the gypsum board core and the facing paper. By combining with the paper surface fibers, the bonding degree between the board core and the facing paper can be improved, the waterproof effect of the facing paper can also be improved, the surface water absorption degree of the gypsum board can be reduced, the cracking between the gypsum board and the facing paper can be prevented, and the service life of the gypsum board can be extended.

[0043] It can be seen that the present invention does not simply improve the hydrophobic effect of the gypsum board core or the facing paper, but by improving the production formula and process of the gypsum board, the connection effect between the gypsum board core and the facing paper is improved, the connection strength is increased, and the waterproof effects of the board core and the facing paper can be improved respectively, thereby reducing the surface water absorption of the gypsum board in multiple aspects.

[0044] In the present invention, a pressing plate and a pressing weight are pressed on the second facing paper to improve the bonding effect between the facing paper and the gypsum board slurry. During the solidification process, the pressing weight reduces the connection gap between the board core and the facing paper, facilitating the continuous reaction of polyvinyl acetate or polyvinyl alcohol in the slurry with the facing paper.

[0045] The present invention also provides a water-resistant gypsum board, which is prepared by the above preparation method. Specifically, by mass, the hemihydrate gypsum powder is 1000 parts, the water reducer is 3.6 parts, PVAC is 2 parts, silicone oil is 1.8 parts, the alkaline catalyst is 0.3 - 1.2 parts, starch is 6 parts, and water is 530 parts.

[0046] According to the above-provided formula, the concentration of the gypsum slurry is relatively high. In order to better shape the gypsum slurry so that it can form a standard floor body, the pressing plate and the pressing weight can provide a flattening force to the gypsum slurry during the pressing process, enabling it to spread as flat as possible towards both ends to form a plate body.

[0047] The calcined gypsum powder is the gypsum powder after two-step calcination and aging.

[0048] The water reducing agent is a naphthalene-based water reducing agent.

[0049] The alkaline catalyst is ordinary 42.5 Portland cement.

[0050] The following provides an example to characterize the surface waterproof effect of this water-resistant gypsum board.

[0051] Example 1:

[0052] 1000 g of calcined gypsum powder, 3.6 g of naphthalene-based water reducing agent, 2 g of PVAC, 1.8 g of silicone oil, 0.3 g of alkaline catalyst, 6 g of starch, and 530 g of water.

[0053] After weighing each raw material according to the above ratio, pour them together into a stirrer containing 530 g of water, let it stand for a while, stir for 1 - 2 min. After stirring evenly, while maintaining the stirring, pour the gypsum slurry onto the facing paper that has been pre-laid, then cover it with another layer of facing paper, and press on the pressing plate and heavy objects;

[0054] After the gypsum slurry has finally set, remove the heavy objects, take out the experimental small board, put it into an oven preheated to 160 ± 2 °C and bake for 30 min, then cool down to 45 ± 2 °C and bake for another 24 h, and then take out the experimental small board.

[0055] Example 2

[0056] The operation is the same as that of Example 1, except that the addition amount of the alkaline catalyst is 0.6 g.

[0057] Example 3

[0058] The operation is the same as that of Example 1, except that the addition amount of the alkaline catalyst is 0.8 g.

[0059] Example 4

[0060] The operation is the same as that of Example 1, except that the addition amount of the alkaline catalyst is 1.2 g.

[0061] Comparative Example 1:

[0062] The operation is the same as that of Example 1, except that the addition amount of the alkaline catalyst is 0.3 g and PVAC is not added.

[0063] Comparative Example 2:

[0064] The operation is the same as that of Example 1, except that the addition amount of the alkaline catalyst is 0.6 g and PVAC is not added.

[0065] Comparative Example 3:

[0066] The operation was the same as that in Example 1, except that the addition amount of the alkaline catalyst was 0.8 g and PVAC was not added.

[0067] The water absorption rate and surface water absorption amount of the experimental small board were tested according to the national standard, and the results are shown in Table 1:

[0068] Table 1

[0069]

[0070] From Table 1, the following conclusions can be obtained:

[0071] (1) By comparing the water absorption rates of Comparative Example 1 - Comparative Example 3, it can be seen that the stronger the alkalinity of the gypsum board (the larger the addition amount of the alkaline catalyst), the lower the water absorption rate of the gypsum board;

[0072] (2) By comparing the water absorption rates of Example 1 and Example 4, it can be seen that it is not the case that the higher the alkalinity, the higher the water absorption rate of the gypsum board. In fact, PVAC and the alkaline catalyst have an optimal ratio, and in this ratio, the water absorption rate of the gypsum board can be reduced to the greatest extent;

[0073] (3) By comparing the surface water absorption of Comparative Example 1 - 3, it can be seen that the addition amount of the alkaline catalyst has no effect on the surface water absorption of the gypsum board (this is because in the case of not adding PVAC, the surface water absorption effect of the gypsum board is related to the facing paper, and at this time, the formula of the gypsum board core has no effect on the facing paper itself);

[0074] (4) By comparing the water absorption amounts of the comparative examples and the examples, it can be seen that the addition of PVAC can significantly reduce the surface water absorption amount of the gypsum board, indicating that polyvinyl acetate (PVAc) can improve the toughness and water resistance of the facing paper, prevent water from seeping from the facing paper into the gypsum board core, and improve the overall surface water absorption resistance of the gypsum board;

[0075] (5) By comparing the water absorption amounts of Example 1 - 4, it can be seen that the higher the addition amount of the alkaline catalyst, the lower the surface water absorption amount of the gypsum board. It can be seen that polyvinyl acetate can be hydrolyzed into polyvinyl alcohol in an alkaline environment, and the more the content of polyvinyl alcohol, the better the water resistance of the facing paper itself, thus reducing the surface water absorption rate of the gypsum board.

[0076] In the preferred scheme, the addition amount of the alkaline catalyst can be preferably selected from 0.8 - 1.2 parts, so that both the water absorption rate and the surface water absorption amount of the gypsum board are at an excellent level.

[0077] In order to maintain the contact effect between the facing paper and the gypsum board core during the production process and improve the connection strength between the facing paper and the core, see Figures 2 to 5As shown in the figure, the present invention further provides a production system for water-resistant gypsum boards, including a mixer 1, a conveyor belt 2, and a drying device 3. The mixer 1 is arranged in the upstream part of the production system for water-resistant gypsum boards, the conveyor belt 2 is arranged in the middle stream part of the production system, and the drying device 3 is arranged in the downstream position. The conveyor belt 2 can convey the gypsum slurry away from the mixer 1 until the gypsum slurry finally sets into a wet board, and the drying device 3 is used to dry the wet board.

[0078] The mixer 1 is used to stir the calcined gypsum powder, water reducer, PVAC, silicone oil, alkaline catalyst, starch, and water until they are uniform, and can achieve automatic feeding with a controllable flow rate during the stirring process. There are various implementation methods for such a mixer 1.

[0079] The drying device 3 can dry the wet gypsum board step by step, including two drying zones. The temperature of the first drying zone is 160 ± 2 °C, and the temperature of the second drying zone is 45 ± 2 °C. After the wet board is dried in the first drying zone, it can be sent to the second drying zone through other conveyor belts. Although the drying time in the second drying zone is long, the temperature is low, which can play a role in reducing production costs and improving production efficiency.

[0080] An inlet 4 is arranged at the end of the conveyor belt 2 close to the mixer 1, and an outlet 5 is arranged at the end of the conveyor belt 2 close to the drying device 3. The inlet 4 allows the first facing paper and the second facing paper to pass through. The mixer 1 can continuously pour the stirred gypsum slurry from the inlet 4 onto the first facing paper. The gypsum slurry forms a plate body between the first facing paper and the second facing paper, and finally sets into a wet board at the outlet 5. The wet board moves continuously during the conveying process. A cutting machine can be used to cut the wet board at a certain distance, and then other transmission devices can be used to send the cut wet board into the above-mentioned drying device 3 for drying.

[0081] Particularly, the conveyor belt 2 can not only play a role in conveying, but also press the gypsum slurry into a plate structure during the conveying process, eliminate the gap between the facing paper and the gypsum slurry, and improve the contact effect between the gypsum slurry and the facing paper. Specifically, fixing plates 6 are arranged at both ends of the conveyor belt 2, and a pressing plate 7 is slidably arranged on the fixing plates 6. The pressing plate 7 can move above the second facing paper, and a pressing weight 8 is arranged on the pressing plate 7. The pressing plate 7 and the pressing weight 8 can shape the gypsum slurry located between the first facing paper and the second facing paper during the movement of the first facing paper.

[0082] As the gypsum board moves, the second facing paper and the first facing paper continuously enter from the paper inlet 4. The pressing plate 7 can change the moving angle of the facing paper, so that the second facing paper wraps around the first facing paper. When the first facing paper, the gypsum slurry, and the second facing paper enter the space between the pressing plate 7 and the conveyor belt 2, the pressing plate 7 and the pressing weight 8 can press the second facing paper to make it closely adhere to the gypsum slurry. At the same time, by pressing the gypsum slurry, the gypsum slurry is spread evenly between the first facing paper and the second facing paper, so that the gypsum board has a uniform thickness.

[0083] Compared with the method of laying the first facing paper, the gypsum slurry, and the second facing paper in sequence and then static pressing, the present invention provides a fully automated method for pressing weights and decompressing. By pulling the formed gypsum board, the unformed gypsum board slurry and the facing paper directly enter the pressing environment and complete solidification during the pressing and forming process. The production efficiency is high, and there is no need to move the pressing plate or the pressing weight, saving time and effort.

[0084] During the forming process, in order to prevent the pressing plate 7 and the pressing weight 8 from moving left and right, a first baffle 9 is arranged between two fixed plates 6 at the paper inlet 4. At the paper outlet 5, a second baffle 10 parallel to the first baffle 9 is also arranged. The pressing plate 7 is arranged between the first baffle 9 and the second baffle 10, and the first baffle 9 and the second baffle 10 limit the pressing plate 7 in the horizontal direction.

[0085] In order to make the facing paper feed more smoothly, the bottom of the first baffle 9 is bent into an arc towards the pressing plate 7, and the arc-shaped side of the first baffle 9 is butted against the pressing plate 7. The second facing paper can adhere to the arc-shaped side of the first baffle 9.

[0086] The arc-shaped side can also prevent the formation of wavy patterns on the surface of the gypsum slurry during feeding, making the bonding area between the gypsum slurry and the second facing paper increase smoothly, thereby improving the bonding degree between the gypsum slurry and the second facing paper.

[0087] In order to prevent the pressing weight 8 from leaving the pressing plate 7 during movement, a surrounding edge 11 is arranged on the periphery of the pressing plate 7. The surrounding edge 11 encloses the top of the pressing plate 7 into a groove, and the pressing weight 8 is arranged in the groove.

[0088] The thickness of the gypsum board body is related to the mass of the pressing weight. To facilitate the replacement of the mass of the pressing weight 8, the pressing weight 8 includes a number of density boards stacked together. The periphery of the board body is fitted on the surrounding edge 11. Each density board has a uniform density and thickness. The total mass of the pressing weight 8 is related to the number of density boards. The more the number of density boards, the greater the mass of the pressing weight 8, and vice versa. In the production process, with the change of environmental temperature and formula, it is necessary to adjust the mass of the pressing weight 8 to adjust the finally formed thickness of the gypsum board body. The pressing weight board proposed by the present invention is easy to adjust, and the density boards are easy to store.

[0089] A notch 12 is provided on the surrounding edge 11. The notch 12 extends downward to the pressing plate 7. The notch 12 is used to expose the density board, facilitating the operator to buckle out the density board.

[0090] The above embodiments are only exemplary embodiments of the present application and are not used to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements within the essence and protection scope of the present application, and such modifications or equivalent replacements should also be regarded as falling within the protection scope of the present application.

Claims

1. A method for producing a water-resistant gypsum board, characterized in that: The steps include: Adding gypsum powder, water reducing agent, PVAC, silicone oil, alkaline catalyst and starch to water in sequence, letting it stand, and stirring it until it is uniform to obtain gypsum slurry; During the stirring process, the gypsum slurry is poured into the first face paper, and then covered with the second face paper, and a pressing plate and a weight are used to press on the second face paper to shape the gypsum slurry into a board body, until the board body is finally set, and the pressing plate is removed to obtain a wet board; The wet board is subjected to distributed drying to obtain the water-resistant gypsum board.

2. The method for producing a water-resistant gypsum board according to claim 1, characterized in that: The formula of the water-resistant gypsum board is as follows, which includes, by weight: 1000 parts of gypsum powder, 3.6 parts of water reducer, 2 parts of PVAC, 1.8 parts of silicone oil, 0.3-1.2 parts of alkaline catalyst, 6 parts of starch, and 530 parts of water.

3. The method for producing a water-resistant gypsum board according to claim 1, characterized in that: The gypsum powder is gypsum powder calcined and aged in two steps; The water reducer is a naphthalene-based water reducer; The alkaline catalyst is ordinary 42.5 silicate cement.

4. The method for producing a water-resistant gypsum board according to claim 1, characterized in that: The stepwise drying comprises the following steps: drying the wet plate at 160±2° C. for 30 minutes, and then drying at 45±2° C. for 24 hours before taking it out.

5. A production system of a water-resistant gypsum board, used in the production method of the water-resistant gypsum board according to any one of claims 1 to 4, characterized in that: The invention comprises a mixer (1), a conveyor belt (2) and a drying device (3), wherein the mixer (1) extrude the mixed gypsum slurry into the conveyor belt (2), the conveyor belt (2) can transport the gypsum slurry away from the mixer (1) until the gypsum slurry is finally set into a wet plate, and the drying device (3) is used to dry the wet plate; The conveyor belt (2) is provided with a paper inlet (4) at the end close to the mixer (1), and the conveyor belt (2) is provided with a board outlet (5) at the end close to the drying device (3). The paper inlet (4) allows the first face paper and the second face paper to pass through. The mixer (1) can continuously pour the stirred gypsum slurry from the paper inlet (4) onto the first face paper. The gypsum slurry forms a board body between the first face paper and the second face paper, and finally sets at the board outlet (5) to form the wet board. Fixed plates (6) are provided at both ends of the conveyor belt (2), and a pressure plate (7) is slidably provided on the fixed plate (6). The pressure plate (7) can move above the second facing paper, and a ballast (8) is provided on the pressure plate (7). The pressure plate (7) and the ballast (8) can shape the gypsum slurry located in the first facing paper and the second facing paper during the movement of the first facing paper.

6. A production system for water-resistant gypsum board according to claim 5, characterized in that: A first baffle (9) is arranged between the two fixed plates (6) on the paper inlet (4), and a second baffle (10) is arranged parallel to the first baffle (9) at the outlet (5). The pressure plate (7) is arranged between the first baffle (9) and the second baffle (10), and the first baffle (9) and the second baffle (10) limit the pressure plate (7) in the horizontal direction.

7. A production system for water-resistant gypsum board according to claim 6, characterized in that: The bottom of the first baffle (9) is bent into an arc shape toward the pressing plate (7), and the arc-shaped side edge of the first baffle (9) is butted against the pressing plate (7), and the second face paper can be attached to the arc-shaped edge of the first baffle (9).

8. A production system for water-resistant gypsum board according to claim 7, characterized in that: The pressure plate (7) is provided with a surrounding edge (11) on its circumference, and the surrounding edge (11) surrounds the top of the pressure plate (7) to form a groove body, and the ballast (8) is arranged in the groove body.

9. A production system for water-resistant gypsum board according to claim 8, characterized in that: The ballast (8) comprises a plurality of density boards stacked together, the four sides of the board body are arranged on the surrounding edge (11) in a close fit, and each density board has uniform density and thickness.

10. A production system for water-resistant gypsum board according to claim 9, characterized in that: A notch (12) is provided on the surrounding edge (11), and the notch (12) extends downward to the pressing plate (7), and the notch (12) is used to expose the density board.

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