JP3713060B2 - Roll coater and molding method of gypsum board using the same - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a roll coater which is a thin coating apparatus and a method for forming a gypsum board using the roll coater.
[0002]
[Prior art]
Gypsum board is widely used as an interior material for buildings because of its fire resistance, sound insulation, workability and economy. Such a gypsum board is a plate-like body in which a core mainly composed of gypsum is coated with a base paper for gypsum board (hereinafter simply referred to as a base paper), and in the manufacturing process, calcined gypsum, adhesion aid, curing accelerator, weight reduction Foam, other additives and water are kneaded with a mixer or the like, and the resulting calcined gypsum slurry (hereinafter referred to as mud) is poured into the lower base paper, Bend a part of the gypsum board to the back side of the gypsum board, pass through the molding machine so that the paste on the side of the upper base paper overlaps the base paper surface on the back side, and spread in the width direction with the upper and lower base paper The slurry on the base paper is coated and formed into a plate shape, then roughly cut after curing, and cut into product dimensions after forced drying.
Here, what is important for molding the gypsum board is that the core constituting the gypsum board and the base paper are bonded together. For example, GB741140 discloses a base paper in order to improve the adhesion. Apply a thin layer of high-density gravity that does not contain foam on the surface of the adhesive, roll it thinly, and flow low-density foam with foam on it, and then cover the base paper or high-density slurry that does not contain foam. A technique for forming a gypsum board by distributing a base paper thinly coated on the surface with a roll is described. Japanese Patent Application Laid-Open No. 5-148001 receives a high specific gravity mud containing an adhesive between an application roll and an idler roll, and supplies the mud from there to the mud adhering to the surface of the application roll. A technique is disclosed in which a thin gypsum layer is provided by transferring to a bonding surface, and a foamed low specific gravity slurry is poured thereon to form a gypsum board.
[0003]
Moreover, drying of gypsum board is mentioned as a big manufacturing factor in connection with gypsum board adhesion. That is, the gypsum board in the forced drying process generally has a relatively faster drying rate at the edge portion or the edge region of the gypsum board than the drying rate at the central portion in the width direction of the gypsum board. For this reason, strength reduction and adhesion failure (dry out) are likely to occur in the edge portion or the edge region due to excessive drying. As a measure for preventing such dry-out, for example, in US Pat. No. 2,672,738, when forming a gypsum board, from the sub-mixers provided at both ends of the slurry on the lower paper poured from the main mixer and above the both ends of the lower paper, respectively. A technique is disclosed in which dry-out is prevented by pouring a slurry with a high specific gravity, forming a gypsum board, and making the core specific gravity of the end of the board larger than the specific gravity of the central portion.
[0004]
[Problems to be solved by the invention]
However, in the prior art roll coater disclosed in GB741140 and JP-A-5-148001, since the rotation direction of the coating roll is the same as the conveying direction of the base paper, the roll is caused by the adhesiveness of the slurry. As a result, the thickness of the thin coating layer is not constant in the transport direction of the base paper, and further, the main component calcined gypsum is water. Since it is a reaction-curing type that cures in contact with the coating, it gradually cures during rotation, narrowing the gap between the coating roll and the idler roll, resulting in a small amount of mud transferred to the coating roll and transferring it thinly. The thickness of the layer changes with time, and the thickness of the thin coating layer is not constant.
On the other hand, in order to remove the slurry on the roll surface after application, even if a scraping plate is provided over the entire longitudinal direction of the roll, the removed slurry falls from the scraping plate to the upper surface of the thin coating layer, eventually Therefore, it becomes difficult to realize a uniform coating thickness.
Furthermore, the mud adhering to the roll side surface or the like hardens, grows up, touches the base paper, causes a piece of paper, and is forced to stop the production line.
[0005]
Further, in the prior art disclosed in US2762738, the low-specific gravity and high-specific gravity slurry flows separately to the center and the edge region of the base paper by the main mixer and the submixer, respectively. The board manufacturing process and process management become complicated.
Accordingly, a first object of the present invention is to provide a roll coater that can improve the adhesion between the gypsum core and the base paper, and a roll coating method using the roll coater.
A second object of the present invention is to provide a roll coater capable of preventing the slurry from hardening before being applied to the base paper, and a roll coating method using the roll coater.
A third object of the present invention is to provide a method for forming a gypsum board that can improve the production efficiency of the gypsum board.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an adhesive property between the core and the gypsum board base paper in a gypsum board formed of a low specific gravity slurry and having a gypsum-based core coated with a gypsum board base paper. In order to improve, in the roll coater that forms a thin layer of high specific gravity slurry on the upper surface of the base paper for gypsum board,
A base paper transport means for transporting the gypsum board base paper in its longitudinal direction;
A receiving material for supporting the base paper for gypsum board from below;
An application roll that extends in the width direction of the base paper for gypsum board, is disposed at a predetermined interval from the upper surface of the base paper for gypsum board, and rotates in a direction opposite to the conveying direction of the base paper for gypsum board;
An application roll rotation driving means for rotating the application roll in a direction opposite to the conveying direction of the base paper for gypsum board;
A scraping roll that is arranged on the upstream side in the conveyance direction of the base paper for gypsum board with respect to the application roll, extends parallel to the application roll, adheres closely to the roll surface of the application roll, and rotates in a direction opposite to the application roll. ,
There is provided a roll coater comprising: a slurry supply means for supplying a high specific gravity slurry on the upper surface of the base paper for gypsum board on the upstream side in the transport direction of the coating roll.
[0007]
According to the present invention , in the roll coater having the above-described configuration, a close contact portion between the coating roll and the scraping roll extends over the entire length of the roll surface of the coating roll, and the roll diameter of the scraping roll is the coating roll. The roll coater is further characterized in that the center height of the scraping roll is smaller than the center height of the coating roll.
[0008]
Preferably, the roll coater further includes a scraping roll rotation driving means for rotating the scraping roll in a direction opposite to the rotation direction of the coating roll, and the rotation speed of the scraping roll is set to be equal to or lower than the rotation speed of the coating roll. .
Preferably, the length of the coating roll is smaller than the width of the gypsum board base paper, and a non-spread portion of the slurry is formed between the end of the coating roll and the edge of the gypsum board base paper. Preferably, the non-extending portion is formed on both sides of the application roll.
More preferably, the coating roll and the scraping roll have the same overall length, and the scraping plate is disposed so as to contact the contact portion at each end of the coating roll and the scraping roll. Preferably, the hardness of the roll surface of the coating roll is greater than the hardness of each of the roll surface of the scraping roll and the receiving surface of the receiving material.
[0009]
The present invention further uses a roll coater configured as described above,
On the upstream side in the transport direction of the coating roll, supplying a high specific gravity slurry on the upper surface of the base paper for gypsum board,
By passing the high specific gravity slurry between the base paper for gypsum board and the coating roll, the high specific gravity slurry is spread in the width direction of the base paper for gypsum board, and the adhesion between the core and the base paper is improved. A thin layer of the high specific gravity slurry to be improved is formed on the gypsum board base paper, and the application roll is rotated in a direction opposite to the conveying direction of the gypsum board base paper to thereby form the gypsum board base paper and the application roll. There is provided a roll coating method for a base paper for gypsum board, wherein the high specific gravity slurry that does not pass between the two is returned to the upstream side in the transport direction by close contact between the roll surface of the coating roll and the roll surface of the scraping roll. .
Preferably, a slurry having a high specific gravity is allowed to flow in the unextended portions at both ends of the application roll, whereby a high specific gravity can be achieved in the edge portion and the edge region of the gypsum board.
[0010]
From another point of view, the present invention relates to the roll coating method having the above-described configuration, and after coating the upper and / or lower gypsum board base paper, the low specific gravity slurry is applied to the lower gypsum board base paper. Provided is a method for forming a gypsum board, characterized in that it is supplied from above to form a laminate of upper paper, slurry and lower paper, and the laminate is dried .
Preferably, before forming the laminate, both edges of the lower gypsum board base paper are folded upward along the longitudinal direction thereof, so that the mud is between the edge of the application roll and the edge of the gypsum board base paper. A damming portion is formed.
[0011]
[Action]
According to the roll coater and the roll coating method of the present invention, the base paper for gypsum board (hereinafter referred to as base paper) is transported in the longitudinal direction by the base paper transport means, and upstream of the base paper in the transport direction from the coating roll by the slurry supply means. By supplying the slurry to the upper surface of the base paper, the slurry on the upper surface of the base paper reaches the spread portion formed between the upper surface of the base paper and the lower end of the roll surface of the coating roll. The coating roll is arranged substantially parallel to the base paper, along the width direction of the base paper, and at a predetermined interval from the upper surface of the base paper, so that the slurry is spread in the width direction of the base paper by the lower end of the roll surface. And thereby a thin layer of slurry can be formed over the entire surface of the base paper. At this time, by rotating the coating roll in the direction opposite to the conveying direction of the base paper, the spread slurry is prevented from adhering to the lower end of the coating roll surface due to its adhesiveness, while the scraping roll is coated. By placing in close contact with the roll surface of the coating roll in parallel with the roll, it is possible to prevent mud from adhering to the coating roll surface on the rotation direction advance side from the close contact portion. It is possible to prevent a change in the transport direction and a change with time, and as a result, the thickness of the thin layer can be made uniform and the adhesion between the gypsum core and the base paper can be improved.
[0012]
When the scraping roll comes into close contact with the coating roll on the upstream side in the conveyance direction of the base paper, the slurry that is not spread by the coating roll in the spreading section adheres to the roll surface of the coating roll that rotates in the reverse direction to the conveyance direction of the base paper, and upstream of the base paper. It moves toward the upper side and reaches the contact portion with the scraping roll, where the slurry moves to the roll surface of the scraping roll . Preferably, the center height of the scraping roll is set to be equal to or less than the center height of the coating roll, and the slurry on the scraping roll surface falls on the base paper on the upstream side in the base paper transport direction from the spreading portion . The slurry that has fallen on the base paper reaches the spreading section again, and part of it spreads and moves to the downstream side in the conveying direction of the coating roll. In particular, it is possible to activate the flow of the sludge damming portion formed upstream of the spreading portion, while finally spreading and transferring it to the downstream side of the coating roll. It becomes possible to prevent hardening of the slurry.
[0013]
According to the gypsum board molding method of the present invention, non-uniform thickness of the thin layer and / or occurrence of dryout is prevented with respect to the upper paper and lower paper of the base paper, and the flow of the mud damming portion is actively performed. by reduction, while improving or maintaining the adhesion between the gypsum core and the base paper, the production line can be avoided to stop the piece of paper or the like by the cured mud, resulting in improved production efficiency of the gypsum board Can be made.
[0014]
【Example】
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings by taking a roll coater for a lower paper as an example.
FIG. 1 is a partial perspective view of a roll coater according to an embodiment of the present invention.
In FIG. 1, reference numeral 10 is a roll coater, and the roll coater 10 includes a slurry supply means 12 for supplying slurry to the upper surface of the base paper A, a coating roll 14 disposed above the base paper A, and a coating roll. 14 of the base paper upstream of the base paper A, the receiving material 18 installed in the lower area of the base paper A, the application roll 14 and the base roll 16 for rotating the application roll and the base roll 16 Means (not shown).
The base paper A is an endless roll paper having a predetermined width, and is supported in the direction indicated by the arrow in FIG. 1 by a transport means (not shown) for transporting the base paper A while being supported by the receiving material 18. It has become.
The slurry supply means 12 is constituted by a pipe line from a mixer (not shown), and the slurry flowing into the base paper surface is 1 as shown in FIG. 1 from the viewpoint of preventing the slurry from staying on the coating roll 14. Is preferred.
[0015]
The application roller 14 and the scooping roller 16 are provided with a common supporting material (both ends of the rotary shafts 19a, b are respectively installed on both sides of the base paper A so as to be positioned with respect to the base paper A while maintaining their relative positions. The applicator roller 14 and the scissor roller 16 are positioned by integrally adjusting the vertical position of each support member and the width direction position of the base paper A, thereby rotating freely. the lower end of the coating roller 14 is adapted to at a desired predetermined distance from the upper surface of the base paper a, and the width direction of the base paper a, the desired exhibition distal portion 20 to be described later is formed.
Next, the application roll 14 will be described. The application roll 14 is a well-known type having a cylindrical shape and an outer surface constituting a roll surface, and is disposed substantially parallel to the base paper A along the width direction of the base paper A. A slurry spreading portion 20 is formed between the upper surface of the base paper A and the lower end of the coating roll 14. In addition, since the coating thickness by the coating roll 14 is preferably 100 to 500 microns, it is preferable to set the predetermined interval of the extended portion 20 within this range.
The length of the coating roll 14 in the longitudinal direction is smaller than the width of the base paper A, and a non-spread portion (not shown) of slurry is formed between each end of the coating roll 14 and each edge of the base paper A. Yes. In general, the width of the non-expanded portion is preferably 10 mm to 50 mm. Accordingly, the slurry spread in the width direction of the base paper A at the spread section 20 protrudes from both ends of the coating roll 14 through the non-spread section, and the edges of the base paper A (both ends are bent from the both ends of the thin layer). The edge of the plasterboard). In the case of the base paper A and the upper sheet of gypsum board, non-spread portion is is not necessarily provided, at both ends of the thin layer to ensure an overlap, width of the roll width or exhibition distal portion 20 Needs to have a width excluding the allowance. The hardness of the roll surface of the coating roll 14 is preferably larger than the hardness of the surface of the scooping roll 16 and the surface of the receiving material 18 from the viewpoint of protecting the roll surface and preventing paper breakage. In the upper area of the coating roll 14, there are provided shower devices 22 in which the jet ports are aligned in the longitudinal direction of the roll and each jet port is directed downward toward the coating roll 14. Water is sprayed onto the roll surface of the coating roll 14 above the close contact portion. The shower device 22 may be used not only during cleaning after the production line is stopped, but also during operation.
[0016]
The wrinkle removing roll 16 is a well-known type similar to the application roll 14 and is arranged in parallel with the application roll 14 and in close contact with the roll surface of the application roll 14. The close contact portion between the scooping roll 16 and the coating roll 14 extends over the entire length of the roll surface of the coating roll 14, and the scooping roll 16 is disposed upstream of the coating roll 14 in the conveying direction of the base paper A. The center height of 16 is equal to or less than the center height of the coating roll 14, and the lower end of the wrinkle removing roll 16 needs not to contact the upper surface of the base paper A, so the roll diameter is smaller than the diameter of the coating roll 14. . Accordingly, the slurry adhering to the roll surface of the coating roll 14 at the spreading portion 20 is transmitted to the scraping roll 16 through the contact portion, and the rotation direction of the scraping roll 16 is opposite to that of the coating roll 14 as will be described later. Therefore, it falls onto the base paper A substantially from the spot, that is, from the vicinity of the close contact portion on the side of the scraping roll 16. Further, the scraping roll 16 and the coating roll 14 have the same length in the longitudinal direction, and as shown in FIG. 1, the scraping plate 26 is disposed so as to be in contact with the close contact portions at the ends of the coating roll 14 and the scraping roll 16. In addition, the mud adhering to the roll side surface is removed, and the adhering mud is prevented from hardening and growing.
[0017]
As shown in FIG. 1, the receiving member 18 includes a receiving table 28 extending in the longitudinal direction of the base paper A, and a receiving roll 30 installed between the tables 28 and immediately below the coating roll 14. The base paper A is supported from below. By covering the surface of the receiving material 30 with, for example, rubber, soft resin or the like, even if foreign matter is mixed between the coating roll 14 and the base paper A on the receiving roll 30, the surface of the rubber or the like is recessed and the base paper A Therefore, the production line can be continued without interruption. The receiving table 28 may be constituted by a surface plate or the like, and the receiving roll 30 may be driven to rotate or may be free.
Each of the coating roll rotation driving means and the take-up roll rotation driving means comprises a known motor and known transmission means for transmitting the rotation of the motor to each rotary shaft, for example, a combination of sprocket and chain. In the driving means, the application roll 14 is rotated in the direction opposite to the conveying direction of the base paper A, and in the removal roll rotation driving means, the removal roll 16 is rotated in the direction opposite to the rotation direction of the application roll 14. It has become. In order to obtain a uniform and stable thin layer on the surface of the base paper, the peripheral speed of the coating roll 14 is preferably equal to or less than the transport speed of the base paper A, and the peripheral speed of the scraping roll 16 is the peripheral speed of the coating roll 14. It is preferable that the speed is not more than the directional speed. An idler may be provided between the coating roll 14 and the wrinkle roll 16 and may be driven by a single rotational driving device.
[0018]
The effect | action is demonstrated below about the roll coater of the above structure.
In advance, the width direction position of the lower sheet of the application roll 14 and the interval between the upper surface of the lower sheet and the lower end of the roll surface of the application roll 14 are adjusted. The lower paper is transported in the longitudinal direction by the base paper transporting means, and the upper surface of the lower paper is supplied by supplying the slurry to the upper surface of the lower paper from the coating roll 14 on the upstream side in the transporting direction of the lower paper. This mud reaches the spreader 20 formed between the upper surface of the lower paper and the lower end of the roll surface of the coating roll 14. Since the coating roll 14 is arranged substantially parallel to the lower paper, along the width direction of the lower paper, and spaced from the upper surface of the lower paper, the slurry is separated from the lower paper by the lower end of the roll surface. It is possible to form a thin layer of slurry across the entire surface of the lower paper. Further, the excess slurry passes through the non-expanded portions formed on both ends of the coating roll 14 and protrudes from both ends of the coating roll 14 to the edge of the lower paper (the edge of the gypsum board when both ends are bent). If the slurry is made to have a high specific gravity, it is possible to easily make the edge slurry high in specific gravity without providing a separate device such as a secondary mixer, thereby preventing dry-out.
[0019]
At this time, by rotating the coating roll 14 in the direction opposite to the conveying direction of the lower sheet, it is possible to prevent the spread mud from trying to adhere to the lower end of the coating roll 14 due to its adhesiveness. Further, by setting the rotation direction of the coating roll 14 to be opposite to the rotation direction of the coating roll 14, mud partially adhered to the surface of the coating roll 14 passes through the coating roll 16 from the downstream side of the coating roll rotation direction of the contact portion 24. Therefore, it is possible to reliably prevent the upstream portion from being transported to the spreading portion 20, so that the thickness of the thin slurry layer in the transport direction of the base paper is made uniform, and further, the operation time of the roll coater 10 is The thickness can be prevented from changing, and as a result, the thickness of the thin layer can be made uniform, and the adhesion between the gypsum core and the lower paper can be improved.
At the same time, the scooping roll 16 is disposed on the upstream side in the conveying direction of the lower sheet from the coating roll 14, and the close contact portion 24 between the scissoring roll 16 and the coating roll 14 extends over the entire longitudinal direction of the roll surface of the coating roll 14. Therefore, the slurry that is not spread by the spreading roll 14 in the spreading section 20 adheres to the roll surface of the spreading roll 14 that rotates in the reverse direction to the conveyance direction of the lower paper, and is transferred upward to the upstream side of the lower paper, At the contact portion 24, the slurry moves to the roll surface of the scraping roll, and the scraping roll rotates in the opposite direction to the coating roll 14, so that it almost falls down on the spot.
[0020]
Here, since the center height of the scraping roll is equal to or less than the center height of the coating roll 14, the slurry on the scraping roll surface can fall from the spreading portion 20 onto the bottom sheet on the upstream side in the sheet transporting direction. Become. Part of the slurry falling on the lower paper is spread and transferred to the downstream side of the coating roll 14, and part of the slurry reaches the spreader 20 again. By repeating this, a circulation loop of the slurry is formed. prevention particular, to revitalize flow stop part amount of mud which is formed upstream of the spread portion 20, eventually it becomes possible to spread, resulting in the cure of the non-spread of the slip by can do. In addition, the wrinkle removing plate 26 removes wrinkles always attached to the side portions of the rolls, cures and grows, and can prevent the occurrence of paper breakage or the like. Further, by cleaning the roll surface of the coating roll 14 by the shower device 22 during operation or during stoppage, the thin layer surface of the slurry spread by the roll surface can be maintained.
As described above, the case of applying to the lower paper has been described as an example. However, the same applies to the upper paper, except that the slurry is not applied to the side edges in order to secure the adhesive margin as described above.
Next, a method for forming a gypsum board using this roll coater will be described below.
FIG. 2 is a process explanatory view partially and schematically showing a molding process of a gypsum board. The lower paper 110 of the base paper for gypsum board is conveyed along the production line. The mixer 120 is disposed at a predetermined position related to the conveyance line, for example, above the conveyance line, and is a type that can supply high specific gravity and low specific gravity slurry by a single mixer, which is separately filed by the present applicant. belongs to. A conventional type mass key may be provided for each of the high specific gravity and low specific gravity slurry. Powders such as calcined gypsum, adhesion aid, effect promoter, additive, foam and water are supplied to the mixer 120. The mixer 120 kneads these raw materials and feeds the high specific gravity slurry 130 through the pipelines 140 and 150. Then, the paper is supplied from the roll coater 100 onto the lower paper 110 and the upper paper 160 on the upstream side in the transport direction. The slurry on the lower paper 110 and the upper paper 160 reaches the spread portion 20 of the roll coater 100, where it is spread as described above, and the thin layer and the edge region of the high specific gravity slurry 130 are the lower paper. A thin layer is formed on top paper 160 on 110. The lower paper 110 is conveyed as it is, and the upper paper 160 is turned in the direction of the lower paper 110 by the turning roller 170, and reaches the forming roller 180 together. Here, between the thin layers formed on the papers 110 and 160, the low specific gravity slurry 200 is supplied from the mixer 120 via the pipe line 190, and thus from the lower paper 110, the slurry 200, and the upper paper 160. A continuous laminate having a three-layer structure is formed, and the laminate reaches a rough cutting cutter (not shown) while curing. A rough cutting cutter cuts a continuous laminated body into a plate body of a predetermined length, and thus a plate-like body formed by covering a core mainly composed of gypsum with a base paper for gypsum board, that is, a raw material for gypsum board. It is formed. The roughly cut laminate is further passed through a drier (not shown), forcedly dried, and then cut into a predetermined product length, thus producing a gypsum board product.
[0021]
【effect】
As is apparent from the above description, according to the roll coater and the roll coating method of the present invention , the thickness of the thin coating layer by the location and time is prevented by preventing the mud from adhering to the coated roll surface and curing. Can be suppressed, thereby making the thickness of the thin coating layer uniform and improving the adhesion between the gypsum core and the lower paper. In addition, according to the roll coater and the roll coating method of the present invention, the gypsum board that prevents the mud from adhering to the surface of the coating roll and the unrolled mud from the coating roll is removed from the coating roll through the contact portion and the scraping roll. By returning to the upstream side of the paper transport direction, a part of the paper is spread and a part is formed to form a mud circulation loop to activate the mud flow. All can be spread, and as a result, hardening of the slurry which is not spread can be prevented. Furthermore, in accordance with the present invention, a non-spread portion of the slurry is formed between the end of the coating roll and the edge of the gypsum board base paper, so that a single roll coater can dry the edge portion or edge area of the gypsum board. to prevent the occurrence of out, thereby it is possible to maintain the adhesion between the gypsum core and the lower paper.
[0022]
According to the gypsum board molding method of the present invention, the flow of the unexpanded slurry is activated while preventing the non-uniform thickness of the thin layer and / or the occurrence of dryout, and The adhesiveness with paper can be improved, and the stop of the production line due to paper breakage can be avoided, and as a result, the production efficiency of gypsum board can be improved.
[Brief description of the drawings]
FIG. 1 is a partial perspective view of a roll coater according to an embodiment of the present invention.
FIG. 2 is a process diagram partially and schematically showing a molding process of a gypsum board.
[Explanation of symbols]
10 roll coater 12 slip supply unit 14 applying rolls 16 refuse removing roll 18 receiving member 19 rotates shaft 20 spread unit 22 shower apparatus 24 contact portion 26 refuse removing plate 28 receiving table 30 receiving roll

Claims (13)

In order to improve the adhesion of the core and the base paper for gypsum board in a gypsum board formed of low specific gravity slurry and having a gypsum-based core coated with a gypsum-based core, a thin layer of high specific gravity slurry In a roll coater for forming on the upper surface of the base paper for gypsum board,
  A base paper transport means for transporting the gypsum board base paper in its longitudinal direction;
  A receiving material for supporting the base paper for gypsum board from below;
  An application roll that extends in the width direction of the base paper for gypsum board, is disposed at a predetermined interval from the upper surface of the base paper for gypsum board, and rotates in a direction opposite to the conveying direction of the base paper for gypsum board;
  An application roll rotation driving means for rotating the application roll in a direction opposite to the conveying direction of the base paper for gypsum board;
  A scraping roll that is arranged on the upstream side in the conveying direction of the gypsum board base paper with respect to the application roll, extends parallel to the application roll, adheres closely to the roll surface of the application roll, and rotates in a direction opposite to the application roll. ,
  A roll coater comprising: a slurry supply means for supplying a high specific gravity slurry to the upper surface of the base paper for gypsum board on the upstream side in the transport direction of the coating roll. The adhesion portion between the coating roll and the scooping roll extends over the entire length of the roll surface of the coating roll, the roll diameter of the scissoring roll is smaller than the diameter of the coating roll, and the center height of the scoring roll is high. The roll coater according to claim 1, wherein the height is set to be equal to or less than a center height of the coating roll. It further has a scraping roll rotation driving means for rotating the scraping roll in a direction opposite to the rotation direction of the coating roll, and the rotational speed of the scraping roll is set to be equal to or lower than the rotational speed of the coating roll. The roll coater according to claim 1 or 2. The length of the coating roll is smaller than the width of the gypsum board base paper, and a non-spread portion of slurry is formed between the end of the coating roll and the edge of the gypsum board base paper. The roll coater according to any one of claims 1 to 3 , wherein the roll coater is characterized.   The roll coater according to claim 4, wherein the non-extending portion is formed on both sides of the coating roll. The total length of the said application roll and the said scooping roll is the same, The scooping board is arrange | positioned so that the said contact | adherence part may be contact | connected in each end of the said applicating roll and the said scooping roll . The roll coater according to any one of claims. The roll coater according to any one of claims 1 to 6 , wherein the hardness of the roll surface of the coating roll is greater than the hardness of each of the roll surface of the scraping roll and the receiving surface of the receiving material. . Using the roll coater according to any one of claims 1 to 7,
On the upstream side in the transport direction of the coating roll, supplying a high specific gravity slurry on the upper surface of the base paper for gypsum board,
By passing the high specific gravity slurry between the base paper for gypsum board and the coating roll, the high specific gravity slurry is spread in the width direction of the base paper for gypsum board, and the adhesion between the core and the base paper is improved. A thin layer of the high specific gravity slurry to be improved is formed on the gypsum board base paper, and the application roll is rotated in a direction opposite to the conveying direction of the gypsum board base paper to thereby form the gypsum board base paper and the application roll. A roll coating method for base paper for gypsum board, wherein the high specific gravity slurry that does not pass between the two is returned to the upstream side in the transport direction by close contact between the roll surface of the coating roll and the roll surface of the scraping roll .   The excess slurry generated when the high specific gravity slurry is spread passes through a non-spread portion between an end of the coating roll and an edge of the gypsum board base paper. Roll coating method for base paper for plasterboard. The roll coating method for base paper for gypsum board according to claim 8 or 9 , wherein a peripheral speed of the coating roll is set to be equal to or lower than a transport speed of the base paper for gypsum board. The roll coating method for base paper for gypsum board according to any one of claims 8 to 10 , wherein the coating thickness by the coating roll is set in a range of 100 to 500 microns.   12. After coating the upper and / or lower gypsum board base paper according to the roll coating method according to any one of claims 8 to 11, a lower specific gravity slurry is applied to the lower gypsum board base paper. A method for forming a gypsum board, comprising: supplying from above, forming a laminate of upper paper, slurry and lower paper, and drying the laminate.   Both edges of the lower gypsum board base paper are bent upward along its longitudinal direction to form a mud-damping portion between the end of the coating roll and the edge of the gypsum board base paper. The molding method of the gypsum board of Claim 12.

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