Method for preparing hydrophobic film on surface of gypsum board

Abstract

The invention discloses a method for preparing a hydrophobic film on the surface of a paper-faced gypsum board, comprising the following steps: applying an alkaline solution mixed with methyl hydrogenated silicone oil on the front of a lower face paper, and then drying a wet gypsum board. There are multiple Si-H groups with active chemical properties in the methyl hydrogenated silicone oil, and then the wet gypsum board is dried. In the process of drying the paper-faced gypsum board under alkaline conditions, the unhydrolyzed Si-H and the water molecules evaporated from the board core continue to hydrolyze into Si-OH, a part of Si-OH is combined with the face paper fiber to fix the hydrophobic group to the front of the gypsum board, and the other Si-OH forms a more stable -Si-O-covalent network through self-condensation to cover the front of the gypsum board, so that a hydrophobic film is formed on the front of the gypsum board.

Description

Technical Field

[0001] The invention relates to the field of gypsum board production lines, and in particular to a method for preparing a hydrophobic film on the surface of a paper-faced gypsum board. Background Art

[0002] The main components of paper-faced gypsum board are gypsum, facing paper and some additives. Both gypsum and facing paper have the characteristics of easy moisture absorption, and the surface of the facing paper is hydrophilic. In a humid environment, moisture will penetrate through the paper surface and enter the gypsum core layer.

[0003] In order to solve this problem, a hydrophobic film can be formed on the front side of the gypsum board to prevent moisture from penetrating through the paper surface and entering the gypsum core layer. It is known that the lower facing paper of the gypsum board is the use side, and the upper facing paper of the gypsum board usually faces the wall or ceiling and is generally not affected by the humid environment. Therefore, it is usually only necessary to form a hydrophobic film on the front side of the lower facing paper. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a hydrophobic film on the surface of a paper-faced gypsum board, so as to solve the technical problem of how to form a hydrophobic film on the front side of the lower face paper of the gypsum board.

[0005] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0006] A method for preparing a hydrophobic film on the surface of a paper-faced gypsum board comprises the following steps: applying an alkaline solution mixed with methyl hydrogen silicone oil on the front surface of a lower face paper, and then drying the wet gypsum board.

[0007] Furthermore, after the lower face paper passes through the lower face paper deflection correcting machine, the alkaline solution is applied to the front side of the lower face paper.

[0008] Furthermore, before the lower face paper passes through the lower face paper scoring machine, the alkaline solution is applied to the front side of the lower face paper.

[0009] Furthermore, a second lower face paper deflection corrector is added between the lower face paper deflector and the lower face paper notching machine, and after the alkaline solution is applied to the front side of the lower face paper, the lower face paper passes through the second lower face paper deflector.

[0010] Furthermore, blank areas with a width of 10 mm to 15 mm are reserved on both sides of the front side of the lower face paper, and the alkaline solution is applied to the areas outside the blank areas.

[0011] Furthermore, the step of applying an alkaline solution mixed with methyl hydrogen silicone oil on the front side of the lower face paper includes: spraying the alkaline solution on the front side of the lower face paper using a spray gun; and smoothing the alkaline solution attached to the front side of the lower face paper using an applying component.

[0012] Furthermore, the number of the spray guns is several, and the several spray guns are arranged side by side at equal intervals along the width direction of the lower face paper, and each of the spray guns can be opened or closed independently; the number of the coating components is at least 2, and the multiple coating components form a continuous and uninterrupted coating area in the width direction of the lower face paper, wherein the position of at least one coating component in the width direction of the lower face paper can be adjusted to change the overall width of the coating area; the step of using the spray gun to spray the alkaline solution on the front side of the lower face paper includes: selectively opening some of the spray guns so that the alkaline solution sprayed on the lower face paper by the spray gun avoids the blank area; the step of using the coating component to smooth the alkaline solution attached to the front side of the lower face paper includes: adjusting the position of the coating component to change the overall width of the coating area so that the edge of the coating area fits the edge of the blank area.

[0013] Furthermore, the step of applying an alkaline solution mixed with methyl hydrogen silicone oil on the front side of the lower face paper also includes: providing a supporting component on the side of the lower face paper facing away from the applying component, the supporting component including a smooth line or surface for supporting the back side of the lower face paper, and using the supporting component to offset the force applied by the applying component to the front side of the lower face paper.

[0014] On the other hand, the step of applying an alkaline solution mixed with methyl hydrogen silicone oil on the front side of the lower face paper also includes: setting a belt conveyor on the side of the lower face paper facing away from the application component, the transmission surface of the belt conveyor is in contact with the back side of the lower face paper, the transmission speed of the belt conveyor is in the same direction and speed as the linear speed of the lower face paper, and the width of the transmission surface of the belt conveyor is greater than the width of the lower face paper.

[0015] Furthermore, the step of applying an alkaline solution mixed with methyl hydrogen silicone oil on the front side of the lower face paper also includes: using a color sensor to detect the printed pattern on the front side of the lower face paper, calculating the linear speed of the lower face paper according to the interval time between the appearance of two adjacent printed patterns, and then adjusting the transmission speed of the belt conveyor so that the transmission speed of the belt conveyor is equal to the linear speed of the lower face paper.

[0016] Compared with the prior art, this application has the following beneficial effects:

[0017] Provided is a method for preparing a hydrophobic film on the surface of a paper-faced gypsum board. The method comprises the following steps: applying an alkaline solution mixed with methyl hydrogen silicone oil on the front side of a lower face paper, wherein the methyl hydrogen silicone oil contains a plurality of Si-H groups with active chemical properties, and then drying the wet gypsum board. In the process of drying the paper-faced gypsum board under alkaline conditions, Si-H that has not yet been hydrolyzed continues to hydrolyze into Si-OH with water molecules evaporated from the board core. A part of the Si-OH is combined with face paper fibers to fix the hydrophobic group to the front side of the gypsum board, and the other Si-OH forms a more stable -Si-O- covalent network through self-condensation and covers the front side of the gypsum board, so that a hydrophobic film is formed on the front side of the gypsum board. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0019] Figure 1 A three-dimensional diagram of a coating device according to an embodiment of the present invention;

[0020] Figure 2 A bottom view of a coating device according to an embodiment of the present invention;

[0021] Figure 3 for Figure 2 The cross-sectional view in the AA direction and the enlarged view of its local structure;

[0022] The numbers in the figure represent the following:

[0023] 1-lower protective paper; 11-blank area; 2-applying component; 21-rag; 22-elastic plate; 3-spray gun; 31-solenoid valve; 4-servo slide; 5-pipeline; 6-belt conveyor; 7-color sensor. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The following provides a method for preparing a hydrophobic film on the surface of a gypsum board, comprising the following steps:

[0026] Before drying the gypsum board, an alkaline solution mixed with methyl hydrogen silicone oil is applied to the front side of the lower face paper 1, and then the gypsum board is dried.

[0027] The hydrophobic film is formed by the following principles:

[0028] The alkaline solution can be potassium hydroxide. Methyl hydrogen silicone oil is a highly polymerized organic compound with multiple chemically active Si-H groups in its molecules. In the process of drying the gypsum board under alkaline conditions, the unhydrolyzed Si-H and the water molecules evaporated from the board core continue to hydrolyze into Si-OH. A part of Si-OH combines with the facing paper fibers to fix the hydrophobic group to the front of the gypsum board, and the other Si-OH forms a more stable -Si-O- covalent network through self-condensation to cover the front of the gypsum board, finally forming a hydrophobic film on the front of the gypsum board.

[0029] It can be seen that the other steps of the method for producing gypsum board do not require any changes. It is only necessary to apply an alkaline solution mixed with methyl hydrogen silicone oil on the front side of the lower face paper 1 before the wet gypsum board is dried to obtain a gypsum board with a hydrophobic film formed on the front side.

[0030] Preferably:

[0031] Before the lower face paper 1 passes through the lower face paper notching machine, an alkaline solution mixed with methyl hydrogen silicone oil is applied to the front side of the lower face paper 1 .

[0032] The location for applying the alkaline solution mixed with methyl hydrogen silicone oil is selected between the lower face paper correction machine and the lower face paper scoring machine of the gypsum board production line. This is because it is difficult to apply the alkaline solution to the scored portion of the lower face paper 1, and it is difficult to form a hydrophobic layer at the edge of the lower face paper 1 of the gypsum board finally obtained. Therefore, it is necessary to apply the alkaline solution before scoring so that a hydrophobic layer can be formed on both sides of the scored portion of the lower face paper 1.

[0033] Furthermore, since glue needs to be applied to the top surface of the flange after the upper face paper is erected so that the upper face paper can be attached to the top surface of the flange, the edges on both sides of the upper face paper cannot be coated with alkaline solution, otherwise the stickiness of the glue attached to the front side of the lower face paper 1 will be reduced.

[0034] In the step of applying the alkaline solution mixed with methyl hydrogen silicone oil on the front side of the lower face paper 1, the following conditions need to be defined:

[0035] A blank area 11 with a width of 10 mm to 15 mm is left on both sides of the lower face paper 1 , and an alkaline solution mixed with methyl hydrogen silicone oil is applied to the area outside the blank area 11 .

[0036] Since the deviation of the lower face paper 1 during the transmission process will make the position of the blank area 11 difficult to control, the following conditions need to be defined: after the lower face paper 1 passes through the lower face paper deviation correcting machine, an alkaline solution mixed with methyl hydrogen silicone oil is applied to the front side of the lower face paper 1.

[0037] Furthermore, since the widths of the lower facing papers 1 of gypsum boards of different specifications are different, it is necessary to prepare coating devices of different widths for the lower facing papers 1 of different widths.

[0038] The coating device comprises at least two coating components 2, which are arranged on the transmission path of the lower face paper 1 and are used to coat the alkaline solution on the front side of the lower face paper 1;

[0039] The two application components 2 can move along the width direction of the lower face paper 1 so that the edge of the application component 2 can be close to one side of the lower face paper 1 and away from the other side of the lower face paper 1, the projections of the two application components 2 in the width direction of the lower face paper 1 are staggered from each other, and the projections of the two application components 2 in the length direction of the lower face paper 1 are partially overlapped, so that the two application components 2 can respectively apply from the middle of the lower face paper 1 to one side of the lower face paper 1, and repeat the application in the middle of the lower face paper 1.

[0040] If the width of the largest gypsum board is 2 times or more than the width of the smallest gypsum board, then two application components 2 are not sufficient to accommodate gypsum boards of any specifications. The operator needs to replace application components 2 of different lengths to adapt to changes in the width of the gypsum board, or expand the number of application components 2 to 3 or more.

[0041] When the smearing device includes three smearing components 2 , one of the smearing components 2 is fixed in the middle of the lower face paper 1 and is symmetrical with respect to the center line of the lower face paper 1 , and the other two smearing components 2 are respectively located on both sides of the smearing component 2 .

[0042] The above embodiment can also be differentiated into more embodiments, for example:

[0043] The smearing device includes three smearing components 2; one of the smearing components 2 is fixed in the middle of the lower face paper 1 and is symmetrical with respect to the center line of the lower face paper 1; the other two smearing components 2 are respectively located on both sides of the smearing component 2, and the two smearing components 2 can both move along the width direction of the lower face paper 1, and their projections in the width direction of the lower face paper 1 overlap with each other.

[0044] Therefore, in many embodiments, the application component 2 only needs to meet the following conditions:

[0045] The overall width of the plurality of application members 2 in the width direction of the lower face paper 1 is adjustable, and the plurality of application members 2 do not interfere with each other when the overall width is adjusted.

[0046] The coating component 2 can be a rag 21, a brush, a roller brush, a spray gun 3 or other existing tools for coating liquid on the surface of the product, and the alkaline solution can be quantitatively transmitted to the rag 21, the brush, the roller brush or the spray gun 3 through a pipeline.

[0047] The following preferred technical means are adopted in this embodiment.

[0048] The coating device comprises: a spray gun 3 and a linear drive;

[0049] A plurality of spray guns 3 are arranged side by side at equal intervals along the width direction of the lower face paper 1, each spray gun 3 is connected to an alkali solution source, and each spray gun 3 can be independently opened to spray the alkali solution onto the surface of the lower face paper 1;

[0050] The number of linear drives is at least 2, and the 2 linear drives are respectively connected to 1 coating component 2. The driving direction of the linear drive is parallel to the width direction of the lower protective paper 1. When the number of coating components 2 is 3, the coating component 2 located in the middle does not need to be driven by the linear drive.

[0051] Specifically, the linear drive adopts a servo slide 4 .

[0052] Each spray gun 3 is connected to a pipe 5 with an alkaline solution flowing therein via a separate solenoid valve 31. The alkaline solution can be stored inside a box (not shown in the figure). The box is connected to the pipe 5 and is located at a high place, so that the inside of the pipe 5 has a pressure that enables the alkaline solution to be sprayed out through the spray gun 3.

[0053] The smearing component 2 includes: a rag 21 and an elastic plate 22; the rag 21 is fixedly connected to the elastic plate 22, the portion where the elastic plate 22 and the rag 21 are connected is a rectangular shape, and the edge of the rag 21 exceeds the edge of the elastic plate 22, and the rag 21 always adheres to the surface of the lower protective paper 1 under the action of the rebound force of the elastic plate 22.

[0054] When the size of the gypsum board changes, the solenoid valve 31 is selectively opened and closed to change the spraying width of the spray gun 3. At the same time, the servo slide 4 drives the elastic plate 22 to move so that the alkaline solution sprayed by the spray gun 3, after being smoothed by the rag 21, just covers the area outside the blank area 11 on both sides of the lower face paper 1.

[0055] Furthermore, since at least two coating components 2 are asymmetric relative to the center line of the lower facing paper 1, when each coating component 2 applies alkaline solution to the front side of the lower facing paper 1, the lower facing paper 1 will deflect to one side, causing the corrected lower facing paper 1 to shift again.

[0056] In order to solve this problem, a device is needed to prevent the coating component 2 from exerting a force on the lower face paper 1 to cause it to deflect, or a lower face paper correction device (not shown) is added between the coating device and the lower face paper scoring device.

[0057] Among them, the device for preventing the smearing component 2 from applying a force to the lower face paper 1 to cause it to deviate includes: a supporting component, which is arranged on the side of the lower face paper 1 facing away from the smearing component 2, and the supporting component is used to support the back side of the lower face paper 1, so that when the smearing component 2 applies a force to the front side of the lower face paper 1, the supporting component applies a reverse force, and the two forces offset each other to avoid the lower face paper 1 from deviating.

[0058] The supporting member may be a roller, a smooth metal plate or the like, which can be used in existing technical means to avoid damaging the lower face paper 1 when rubbing against the back side of the lower face paper 1 .

[0059] The following preferred technical means are adopted in this embodiment.

[0060] The device for preventing the smearing component 2 from exerting a force on the lower face paper 1 to cause it to deviate includes: a belt conveyor 6, the transmission surface of the belt conveyor 6 is in contact with the back of the lower face paper 1, the transmission speed of the belt conveyor 6 is in the same direction and speed as the linear speed of the lower face paper 1, and the width of the transmission surface of the belt conveyor 6 is greater than the width of the lower face paper 1.

[0061] Furthermore, in order to ensure that the transmission speed of the belt conveyor 6 is the same as the linear speed of the lower facing paper 1, in this embodiment, the linear speed of the lower facing paper 1 is also detected by a color sensor 7. The color sensor 7 is installed between the lower facing paper deflection correction machine and the belt conveyor 6, and the detection end of the color sensor 7 faces the front side of the lower facing paper 1. The color sensor 7 is used to detect the printed pattern on the front side of the lower facing paper 1.

[0062] The printed pattern is printed on the surface of the lower face paper 1 by a printing roller before passing through the deflection correction machine. Usually, the printed pattern is the manufacturer's name, specification and batch of the gypsum board. Usually, the color sensor 7 is set in the middle of the lower face paper 1, and the sensing color is black.

[0063] The controller calculates the linear speed of the lower face paper 1 according to the interval time between two adjacent printed patterns, and then adjusts the transmission speed of the belt conveyor 6 so that the transmission speed of the belt conveyor 6 is equal to the linear speed of the lower face paper 1. There is no relative movement between the transmission surface of the belt conveyor 6 and the lower face paper 1, and no relative friction is generated.

[0064] The operator can also use a photoelectric encoder instead of the color sensor 7. The photoelectric encoder is used to detect the rotation speed of the roller that transmits the lower protective paper 1, and then calculate the linear speed of the lower protective paper 1 through the controller. However, this calculation result is not accurate, and there is a problem of slippage between the lower protective paper 1 and the roller.

[0065] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A method for preparing a hydrophobic film on the surface of a gypsum board, characterized in that: The method comprises the following steps: leaving blank areas with a width of 10 mm to 15 mm on both sides of the front side of the lower face paper, spraying an alkaline solution containing methyl hydrogen silicone oil on the parts outside the blank areas with a spray gun, smoothing the alkaline solution attached to the front side of the lower face paper with a coating component, the number of the coating components is at least 2, and the plurality of coating components form a continuous and uninterrupted coating area in the width direction of the lower face paper, wherein the position of at least one coating component in the width direction of the lower face paper can be adjusted to change the overall width of the coating area, arranging a belt conveyor on the side of the lower face paper facing away from the coating component, the transmission surface of the belt conveyor is in contact with the back side of the lower face paper, thereby offsetting the force applied by the coating component on the front side of the lower face paper, the transmission speed of the belt conveyor is in the same direction and speed as the linear speed of the lower face paper, the width of the transmission surface of the belt conveyor is greater than the width of the lower face paper, and then drying the wet gypsum board.

2. The method for preparing a hydrophobic film on the surface of a gypsum board according to claim 1, characterized in that: After the lower face paper passes through the lower face paper deflection correcting machine, the alkaline solution is applied to the front side of the lower face paper.

3. The method for preparing a hydrophobic film on the surface of a gypsum board according to claim 2, characterized in that: Before the lower face paper passes through the lower face paper scoring machine, the alkaline solution is applied to the front side of the lower face paper.

4. The method for preparing a hydrophobic film on the surface of a gypsum board according to claim 1, characterized in that: The number of the spray guns is several, and the spray guns are arranged side by side at equal intervals along the width direction of the lower face paper, and each of the spray guns can be opened or closed independently; The step of using a spray gun to spray the alkaline solution containing methyl hydrogen silicone oil on the part other than the blank area includes: selectively opening part of the spray gun so that the alkaline solution sprayed by the spray gun on the lower face paper avoids the blank area; The step of smoothing the alkaline solution attached to the front side of the lower face paper using the smearing member includes: adjusting the position of the smearing member to change the overall width of the smearing area so that the edge of the smearing area fits the edge of the blank area.

5. The method for preparing a hydrophobic film on the surface of a gypsum board according to claim 4, characterized in that: The step of using a spray gun to spray the alkaline solution containing methyl hydrogen silicone oil on the part outside the blank area also includes: A color sensor is used to detect the printed pattern on the front side of the lower face paper, and the linear speed of the lower face paper is calculated according to the interval time between two adjacent printed patterns. Then, the transmission speed of the belt conveyor is adjusted so that the transmission speed of the belt conveyor is equal to the linear speed of the lower face paper.

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