Method for manufacturing gypsum board

Abstract

The purpose of the present invention is to develop a technology that can be applied to an actual continuous manufacturing process of gypsum boards, and that can effectively suppress wrinkles occurring in a base paper constituting a gypsum board product obtained by a gypsum board manufacturing method by a simple method without using chemical substances. Provided is a technique whereby a gypsum board having excellent quality can be stably manufactured with good yield. Provided is a method for manufacturing a gypsum board, the method comprising a step for forming a plate-like laminate in which a gypsum material layer is laminated between an upper sheet and a lower sheet of a base paper for a gypsum board, and conveying the plate-like laminate at the same time. The process comprises the following steps: arranging lower paper on a running conveying forming belt, continuously pouring gypsum slurry serving as a raw material of a gypsum material layer on the conveyed lower paper, and forming a plate-shaped laminated body by laminating upper paper on the gypsum slurry by using a forming machine, the plate-shaped laminated body is conveyed to the rough cutting machine by using the conveying molding belt, and water is sprayed or coated on the paper at a position between the arrangement part of the molding machine and the arrangement part of the rough cutting machine and at a position 1 / 4 of the position between the arrangement part of the molding machine and the arrangement part of the rough cutting machine or at a position closer to the side of the molding machine than the 1 / 4 position.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a gypsum board for continuously manufacturing a gypsum board, and to a technique for providing a gypsum board product that can suppress "wrinkles" generated in base paper constituting the manufactured gypsum board by a simple method. More specifically, the present invention relates to a method for manufacturing a gypsum board, wherein when a gypsum board product is continuously manufactured on a conveyor molding belt also called a conveyor belt, in order to improve the productivity of the gypsum board, when the speed of the conveyor belt is increased compared to the past to manufacture the gypsum board at a high speed, or when a lightweight paper is used as the base paper for the gypsum board, "wrinkles" that tend to occur on the base paper of the manufactured gypsum board can be suppressed, and the product yield can be improved. Background Art

[0002] Gypsum board is an interior material and exterior base material that uses gypsum as a core material and is covered on both sides with gypsum board base paper and formed into a plate shape. Gypsum board has very excellent properties as a building material. Therefore, it quickly became popular after World War II and is now widely used. Gypsum board is manufactured and mass-produced in the following way. First, gypsum slurry made by mixing gypsum and water is poured between the lower paper (the paper surface of the gypsum board) and the upper paper (the paper back of the gypsum board) called gypsum board base paper that are continuously discharged and formed into a plate shape. The gypsum is solidified while being transported by the conveyor belt, and then it is roughly cut and moved to the drying process to dry the excess water. After that, it is cut according to the product size and manufactured continuously. More specifically, gypsum board is continuously manufactured through the following series of processes: gypsum slurry is continuously poured on the lower gypsum board base paper before being continuously fed into the molding machine, and the slurry is piled up and transported, and the upper gypsum board base paper is stacked (covered) on the piled material by the molding machine and passed through a roller, an extruder, etc., to form a continuous plate-like stack on a conveyor belt. Then, the continuous plate-like stack is roughly cut into a specified size, forced dried to dry the remaining water, and then finely cut into a specified product size.

[0003] In the above manufacturing process, the continuous plate-like laminated body formed on the conveyor belt is not dried, but retains excess moisture from the gypsum slurry. Therefore, the gypsum board base paper constituting the above plate-like laminated body is placed on the conveyor molding belt in a state moistened with the moisture and conveyed. If the gypsum board base paper conveyed in this state is subjected to uneven stress, etc., crepe-like or striped wrinkles may sometimes be generated on the surface of the gypsum board base paper. In this case, the "wrinkling" of the gypsum board base paper may sometimes become a defective product instead of a finished product due to the degree of wrinkling, and therefore, the "wrinkling" is an important issue that affects the yield of the product.

[0004] In order to deal with such wrinkle defects, i.e., "wrinkling" of gypsum board base paper, the following solution is proposed in Patent Document 1. Specifically, the following method is disclosed: when manufacturing gypsum board, a lubricant is applied to the outer surface of the gypsum board base paper on the conveyor molding belt of the gypsum board or the surface of the conveyor molding belt in contact with the gypsum board, thereby imparting hydrophobicity and sliding properties to the outer surface of the gypsum board base paper, thereby preventing the occurrence of wrinkles and paper picking at the same time.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2006-82487 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, the above-mentioned prior art has the following problems: a lubricant (hereinafter referred to as "agent") as a chemical substance needs to be applied to the interface between the bottom paper of the gypsum board base paper and the conveyor belt, which makes the manufacturing process complicated, and since a hydrophobic and slippery agent is used, the cost of the agent is increased, and the agent may remain on the bottom paper.

[0010] In recent years, the actual situation is that the base paper used for gypsum board has been newly developed and the weight has been continuously reduced, but there is a problem of "wrinkling" as described below, and no progress has been made in practical application. In addition, although higher productivity is required, according to the research of the present inventors, the "wrinkling" mentioned above in gypsum board products tends to increase, and the present inventors have realized that it is urgent to develop a technology to suppress "wrinkling".

[0011] Since gypsum board is a widely used interior building material and exterior base material, and is also a functional material such as fire resistance, sound insulation, and humidity regulation, gypsum board is required to achieve improved product quality and higher productivity by improving the constituent materials. For example, as described below, the technology of lightweighting gypsum board base paper, which is indispensable in gypsum board products, is constantly developing. In the past, gypsum board base paper usually has a basis weight of 270g / m 2 ~360g / m 2Here, for the base paper used on the surface side of the gypsum board as an interior building material and an exterior base material, excellent strength, smoothness, and water resistance are required. On the other hand, it is considered that for the base paper used on the back side of the gypsum board, in order to fit well with the gypsum layer formed by the poured gypsum slurry, the base paper is preferably a porous paper with high water absorption. In addition, a certain degree of air permeability is required for the base paper to allow the remaining water to escape when the gypsum layer is cured. In this regard, through the recent development of the manufacturing technology of base paper for gypsum board, it has become possible to produce a base paper with a basis weight of 270g / m 2 ~360g / m 2 The board has the same strength and air permeability, but its basis weight is about 80g / m 2 ~200g / m 2 Base paper within the range of (hereinafter sometimes referred to as "light paper").

[0012] However, according to the research of the present inventors, it is found that when the above-mentioned light-weight paper is used as the base paper for gypsum board, there is a tendency that the wrinkle defect described above is more and more likely to occur. Therefore, there is a problem that it is extremely difficult to apply light-weight paper in the actual continuous manufacturing process of gypsum board, which aims to stably manufacture high-quality gypsum board products with suppressed "wrinkles" at a high yield rate.

[0013] In addition, there are the following problems as other causes of "wrinkling". Recently, in order to improve the productivity of gypsum boards, it is sought to increase the manufacturing speed. However, when gypsum boards are continuously manufactured in the series of processes described above, as the manufacturing speed increases, phenomena such as an increase in the mechanical vibration of the conveyor molding belt and an increase in the friction between the gypsum board base paper on the conveyor molding belt and the belt surface occur. Therefore, when the manufacturing speed is increased, the tendency of fine wrinkles in the form of crepes or stripes to occur on the surface of the gypsum board base paper in contact with the conveyor molding belt, which is believed to be caused by the above phenomenon, increases. The inventors of the present invention recognize that since the increase in the manufacturing speed will also lead to an increase in "wrinkling", it is imperative to develop a technology that can manufacture high-quality gypsum board products with suppressed "wrinkling" with good yield, stability and good production efficiency even when the productivity is increased.

[0014] Therefore, the object of the present invention is to develop a technology that can be applied to an actual continuous manufacturing process of gypsum boards by effectively suppressing "wrinkling" generated in base paper constituting the manufactured gypsum boards by a simple method without using chemical substances (agents) in a manufacturing method of gypsum boards for continuously manufacturing gypsum boards, and to provide a technology that can improve production efficiency with a good yield and stably manufacture gypsum boards of excellent quality.

[0015] Solutions for solving problems

[0016] The above object is achieved by the method for producing a gypsum board of the present invention described below.

[0017] [1] A method for manufacturing a gypsum board, which is a continuous method for manufacturing a gypsum board, the method comprising a molding and conveying step, in which a plate-like laminate is molded and conveyed while the plate-like laminate is molded, the plate-like laminate being formed by laminating a gypsum slurry as a raw material of a gypsum material layer of the gypsum board between a base paper for an upper gypsum board and a base paper for a lower gypsum board, wherein the molding and conveying step comprises the following series of processes: before the lower paper is continuously fed into a molding machine, The gypsum slurry is continuously poured on the base paper for gypsum board, the base paper for upper gypsum board is stacked on the poured gypsum slurry by a molding machine to form a plate-like laminate, the molded plate-like laminate is transported to a rough cutter by a conveyor molding belt, and water is sprayed or applied to the base paper for upper gypsum board at a position between the configuration position of the molding machine and the configuration position of the rough cutter, at a position that is 1 / 4 of the upstream side (molding machine side) between the two positions, or at a position on the molding machine side that is upstream of the 1 / 4 position.

[0018] As a preferred embodiment of the method for producing the gypsum composition of the present invention, the following embodiments are mentioned.

[0019] [2] The method for manufacturing a gypsum board according to [1] above, wherein the basis weight of the base paper for the upper gypsum board and the basis weight of the base paper for the lower gypsum board are both 80 g / m 2 ~200g / m 2 within the range.

[0020] [3] The method for producing a gypsum board according to [1] or [2] above, wherein the basis weight of the base paper for the upper gypsum board is 5 g / m smaller than the basis weight of the base paper for the lower gypsum board. 2 ~60g / m 2 .

[0021] [4] The method for producing a gypsum board according to any one of [1] to [3] above, wherein the spraying amount or coating amount of the water is 2.0 g / m 2 ~200g / m 2 within the range.

[0022] [5] The method for producing a gypsum board according to any one of [1] to [4] above, wherein the conveying speed of the conveyor molding belt is 60 m / min or more.

[0023] Effects of the Invention

[0024] According to the present invention, in a method for manufacturing gypsum boards that continuously manufactures gypsum boards, a remarkable effect of being able to effectively suppress "wrinkles" generated in the gypsum board base paper of the manufactured gypsum board product by a simple method without using chemical substances (agents) can be obtained. In addition, since the present invention is a technology that can be applied to a continuous manufacturing process of gypsum boards of a real machine used in the actual process of manufacturing gypsum boards, according to the present invention, a method for manufacturing gypsum boards with high practical value that can stably manufacture gypsum board products of excellent quality with a good yield can be provided. In addition, according to the present invention, in the continuous manufacturing process of gypsum boards, when the speed of the conveyor molding belt that may be the cause of "wrinkles" is increased, it is also possible to suppress "wrinkles" generated in the base paper constituting the gypsum board, thereby improving productivity and being able to more efficiently and stably manufacture gypsum boards of excellent quality with a good yield. In addition, according to the present invention, in the continuous manufacturing process of gypsum boards, even when using lightweight paper that is extremely difficult to use, gypsum boards with excellent quality can be stably manufactured with a good yield, thereby expanding the range of choices for gypsum board base paper and obtaining various gypsum board products. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram for explaining the manufacturing process of the manufacturing method of the gypsum board of this invention.

[0026] Figure 2 It is used for Figure 1 A schematic diagram illustrating a portion of a formed plate-shaped laminated body in a forming and conveying step in a method for producing a gypsum board. DETAILED DESCRIPTION

[0027] Hereinafter, the preferred embodiment of the invention will be cited to illustrate the present invention. The inventors of the present invention have conducted in-depth research on various methods in order to further increase the production speed of gypsum boards in the process of continuously manufacturing gypsum boards and use the recently improved lightweight paper for gypsum board base paper. In the process, one of the causes of wrinkles on the surface of gypsum boards when lightweight paper is used was found. This point is explained below. In a series of manufacturing processes of gypsum boards, as described above, the plate-like laminated body arranged on the conveyor molding belt for transportation is not dried, but retains excess moisture from the gypsum slurry. Although the gypsum board is covered with the base paper for gypsum boards, the base paper continues to swell during the molding and conveying process due to the excess moisture. Here, usually, for gypsum boards manufactured through a series of processes, the lower surface of the lower paper arranged on the conveyor molding belt is formed as the surface of the gypsum board. In contrast, according to the research conducted by the present inventors, if there is a difference in swelling between the lower paper forming the surface of the gypsum board and the upper paper forming the back surface, crepe-like or stripe-like wrinkles will be generated on the surface of the gypsum board base paper on the conveyor molding belt.

[0028] Here, as the reasons for the difference in swelling state between the upper paper and the lower paper of the gypsum board base paper in the molding and conveying process, the following reasons can be cited. In the molding and conveying process, the gypsum slurry is poured onto the lower paper before being continuously fed into the molding machine, and is vibrated by the vibrator as needed while advancing to the molding machine to degas the gypsum slurry. During this period, of course, only the lower paper of the gypsum board base paper is in contact with the gypsum slurry, so that only the lower paper swells. On the other hand, the upper paper contacts the gypsum slurry poured onto the lower paper at a position just before the molding machine. In addition, the upper paper will start to swell from the moment of contact, so there will be a difference between the upper paper and the lower paper of the gypsum board base paper at the beginning of the swelling. The difference in the time when the lower paper and the upper paper start to swell is considered to be one of the reasons for the difference in swelling between the lower paper and the upper paper in the gypsum board base paper.

[0029] In a gypsum board production line for continuously manufacturing gypsum board products, as described above, a continuous plate-like laminate is formed on a conveyor molding belt by a molding machine, etc., and the plate-like laminate is conveyed to the next rough cutting machine. In the plate-like laminate on the conveyor molding belt during transportation, the upper gypsum board base paper is in the following state: its inner side is in contact with the gypsum slurry and the outer side is in contact with the atmosphere, so the excess water evaporates easily. On the other hand, the lower gypsum board base paper is in the following state: its inner side is in contact with the gypsum slurry and the outer side is in contact with the molding belt, so the excess water evaporates less easily than the upper paper. The inventors of the present invention have found that, in addition to the swelling difference caused by the difference in the start time of swelling mentioned above, in particular, the difference in the degree of evaporation of the excess water of the lower and upper papers on the conveyor molding belt is the main reason for the difference in the degree of swelling state of the lower and upper papers in the gypsum board base paper.

[0030] The inventors of the present invention have conducted in-depth research based on the above-mentioned findings, and have completed the present invention as a result. That is, the inventors have paid attention to the fact that the lower paper in the above-mentioned gypsum board base paper is in a state where the excess water compared to the upper paper is difficult to evaporate, or in other words, the upper paper is in a state where the excess water compared to the lower paper is easy to evaporate, which is generated in the production line of gypsum boards for continuously manufacturing gypsum board products, and have conducted in-depth research, and have achieved the structure and effect of the present invention as a result. In view of the difference in swelling state observed between the upper paper and the lower paper of the above-mentioned gypsum board base paper, the inventors of the present invention have anticipated that by supplying water to the upper paper constituting the plate-shaped laminated body on the conveyor molding belt, which is in a state where the excess water is easy to evaporate, the difference in swelling state generated between the upper paper and the lower paper of the gypsum board base paper can be improved, and as a result, the "wrinkling" of the gypsum board base paper can be suppressed, and the present invention has been completed.

[0031] The inventors of the present invention have conducted repeated studies based on the above-mentioned insights, and as a result, have found that by such an extremely simple method as spraying or applying water to the upper paper of the gypsum board base paper constituting the plate-like stack on the conveyor molding belt (i.e., replenishing moisture to the upper paper), it is possible to effectively suppress the "wrinkling" of the gypsum board base paper in the final gypsum board product. It has also been found that in terms of suppressing the above-mentioned "wrinkling" as the purpose of the present invention, the position where water is replenished to the upper paper of the gypsum board base paper constituting the plate-like stack on the conveyor molding belt is extremely important. Specifically, it has been found that in a series of operations on a gypsum board production line for continuously manufacturing gypsum board products, replenishing moisture to the upper paper by spraying water, etc., at a position between the configuration position of a molding machine for stacking the upper paper of the gypsum board base paper on the gypsum slurry and the configuration position of a rough cutting machine for roughly cutting the formed plate-like stack, and at a position 1 / 4 of the upstream side (molding machine side) of the position between the above positions, or at a position on the molding machine side upstream of the above 1 / 4 position, can bring effective results (refer to Figure 1 ).

[0032] In the present invention, it is important to alleviate the difference in swelling state between the upper paper and the lower paper of the gypsum board base paper described above by supplying water to the upper paper constituting the plate-like laminate on the conveyor molding belt. Moreover, the operation of supplying water to the upper paper is performed at the above-mentioned more effective position. Therefore, as long as water can be supplied to the upper paper of the gypsum board base paper, the method of supply is not particularly limited, and is defined as "spraying water or applying water" in the present invention. In addition, considering the above-mentioned purpose and the ease of drying after the water supply, it is expected to supply water to the upper paper without omission by a simple method with a small amount of water, so spraying water is preferred. As water, industrial water, tap water, well water, purified water, etc. can be cited. In short, in the manufacturing method of the present invention, only water is sprayed without using chemicals, so it is extremely useful as a method for manufacturing gypsum board products as interior building materials.

[0033] Reference Figure 1 and Figure 2The production line of gypsum board for continuously manufacturing gypsum board products is described. As described above, in the production line of gypsum board, the formed plate-shaped laminated body 4 is arranged on the running conveyor molding belt 10 and transported, and at the same time, the base paper 1 for the lower paper gypsum board and the base paper 3 for the upper paper gypsum board are transported to the molding machine 20. The gypsum slurry 2 is continuously poured from the mixer 6 onto the lower paper gypsum board base paper 1 that is continuously transported, and the upper paper gypsum board base paper 3 is stacked on the poured gypsum slurry 2 by the molding machine 20 to form the plate-shaped laminated body 4. Then, the formed plate-shaped laminated body 4 is transported to the rough cutter 30 by the conveyor molding belt 10, and is roughly cut into a desired length by the rough cutter 30 to form a plate shape. In addition, the roughly cut board is forced to dry by the dryer 40, and then it is finely cut into the desired product size by the fine cutter 50. Through such a series of processes, the gypsum board product is continuously manufactured.

[0034] The manufacturing method of the gypsum board of the present invention is characterized in that, in the above series of steps, Figure 1 As shown, at a position between the arrangement position of the molding machine 20 and the arrangement position of the rough cutter 30, and at a position of 1 / 4 of the distance on the upstream side (molding machine side) or at a position on the molding machine 20 side closer to the upstream than the above 1 / 4 position, water is sprayed or applied (i.e., water is supplied) to the upper gypsum board base paper 3 stacked for molding the plate-shaped laminated body 4 by a water sprayer 5. By configuring in this way, the problem of "wrinkling" of the gypsum board base paper of the gypsum board product can be effectively suppressed.

[0035] In contrast, the present inventors found that even if water is supplied by spraying water or the like at a position on the side of the rough cutter 30 far from the position of the molding machine 20 downstream of the position of 1 / 4 of the upstream side (molding machine side) (hereinafter referred to as "spraying water"), the above-mentioned significant effect cannot be obtained. Details on this point will be described later. The present inventors considered the following as to the reason why the problem of "wrinkling" of the base paper for gypsum board can be effectively suppressed by spraying water on the upstream side close to the molding machine 20 in the structure specified in the above-mentioned present invention compared with the case of spraying water at a position downstream of the position of 1 / 4 of the upstream side (molding machine side). First, compared with the previous manufacturing method without spraying water, "wrinkling" is suppressed by spraying water to the upper paper, so it is considered that one of the reasons can be reduced by spraying water The swelling difference between the lower paper and the upper paper in the base paper for gypsum board described above. In addition, it was found that the effect of suppressing "wrinkling" varies greatly depending on the position of spraying water, and it can be inferred that the main reason for obtaining a more significant effect by adopting the structure of spraying water at the position specified in the present invention is the following. That is, it is considered that a major reason is that in order to more effectively prevent the swelling difference between the lower paper and the upper paper in the base paper for gypsum board, it is necessary to spray water on the upper paper before the gypsum slurry solidifies. After the gypsum slurry starts to solidify, even spraying water cannot effectively swell the upper paper.

[0036] As described above, the effect of the present invention can be obtained if the position is between the position where the molding machine 20 is arranged and the position where the rough cutter 30 is arranged, and is 1 / 4 of the position on the upstream side (molding machine side) between them or a position on the molding machine 20 side closer to the upstream than the 1 / 4 position. According to the research of the present inventors, by spraying water at a position closer to the molding machine 20, for example, 1 / 8 or 1 / 16, a gypsum board product with further suppressed "wrinkling" can be obtained. In addition, as for the amount of sprayed water, it was confirmed that as long as 2.0 g / m 2 ~200g / m 2 The effect can be obtained within the range of . Considering the subsequent drying, it is preferred that the amount of water sprayed is as small as possible. According to the research of the present inventors, for example, by spraying 10g / m 2 ~100g / m 2 An amount of water of about 100% can achieve a stable effect in suppressing "wrinkling".

[0037] The amount of the sprayed water can be adjusted very easily by the following method: Specifically, the amount of the spray can be easily adjusted by using a conventionally known spray device and adjusting the opening of a spray regulator for spraying water using the production apparatus of the present invention.

[0038] What is particularly important in the present invention is that water is supplied to the upper paper at a specific position specified in the present invention in order to alleviate the difference in swelling state between the upper paper and the lower paper of the base paper for gypsum board, and the amount of water sprayed can be sprayed by a known spraying device, and an excellent effect can be obtained by a simple operation. That is, in the present invention, by setting a structure in which water is sprayed at a specific position specified in the present invention, the difference in swelling between the upper paper and the lower paper that affects "wrinkling" is reduced, and as a result, the excellent effect of the present invention is obtained.

[0039] For the above reasons, the size of water droplets from the spray device when spraying water is not particularly limited. Since it is desired to supply water to the upper paper of the base paper for gypsum board without omission, as the spray device used in the manufacturing method of the present invention, for example, a spray device with a water particle diameter of about 5 μm to 300 μm when spraying water can be preferably used. In addition, the size of water droplets from a known spray device is within this range.

[0040] According to the research of the present inventors, the "wrinkles" generated in the base paper for gypsum boards, which are the cause of defective products in the manufacturing method of gypsum boards for continuously obtaining gypsum board products, tend to occur frequently when the speed of the conveyor molding belt is increased as described above. In view of this, according to the manufacturing method of gypsum boards of the present invention, it is confirmed that the "wrinkles" generated in the base paper for gypsum boards can be reliably reduced and suppressed even when the speed of the conveyor molding belt in operation is 60 m / min, which is the operating condition of a normal production line, and the speed is increased compared to this, for example, to 90 m / min or 120 m / min to increase productivity.

[0041] Regarding the object of the present invention, i.e., suppressing the "wrinkling" that occurs in the base paper of the obtained gypsum board product, which is the cause of defective products in the manufacturing method of gypsum board for continuously obtaining gypsum board products, spraying water at the specific position described above is effective. The present inventors conducted further research and found that in addition to the above method, the following method is also effective. As described above, a base paper with a basis weight of about 80 g / m 2 ~200g / m 2 Although lightweight paper of a certain range is expected to reduce the weight of gypsum board products, it is extremely difficult to apply lightweight paper in the actual continuous manufacturing process of gypsum board. The main reason is that, especially when lightweight paper is used as base paper for gypsum board, wrinkles in the base paper of gypsum board products are more and more likely to occur, and defective products caused by "wrinkles" in the base paper are increasing.

[0042] The present inventors have conducted in-depth research on the above-mentioned problem, and have confirmed that: in the continuous manufacturing process of gypsum board, water is supplied by spraying water on the upper gypsum board base paper at a position within the range specified in the present invention, so that "wrinkling" can be suppressed even when lightweight paper is used for gypsum board base paper. Based on this understanding, the present inventors have conducted further research to stably obtain a better "wrinkling" suppression effect when lightweight paper is used for gypsum board base paper. As a result, it was found that when lightweight paper is used for gypsum board base paper to manufacture gypsum board, in addition to spraying water on the upper paper of the gypsum board base paper as described above, the following design is also performed on the gypsum board base paper used, which is effective in obtaining a stable effect. Specifically, with respect to the structure of the gypsum board base paper, the following structure was found: when the basis weight is 80g / m 2 ~200g / m 2 When using lightweight paper in the range of 500 to 800 grams as the upper gypsum board base paper and the lower gypsum board base paper, it is preferred to use a base weight of 5 g / m2 less than that of the lower gypsum board base paper on the surface side of the gypsum board. 2 ~60g / m 2 The base paper with a basis weight of about 10 g / m is used as the upper gypsum board base paper on the back side of the gypsum board product. In addition, according to the research of the present inventors, it has been confirmed that: as a combination of the upper paper and the lower paper, for example, by making the difference in the basis weight of 10 g / m 2 As described above, a more stable effect can be obtained for suppressing the "wrinkling" generated in the base paper. In the actual continuous manufacturing process of gypsum board, for example, it is preferred to use a base paper with a basis weight of 100 g / m 2 ~180g / m 2 The details of the combination of the upper paper and the lower paper having different basis weights will be described later.

[0043] As described above, the manufacturing method of the gypsum board of the present invention is configured to spray water on the upper paper gypsum board base paper constituting the plate-like laminated body at the position specified in the present invention, and the plate-like laminated body is formed by stacking the upper paper gypsum board base paper on the gypsum slurry poured on the lower paper gypsum board base paper, and other than this, it is the same as the actual continuous manufacturing process of the gypsum board. In addition, in a preferred embodiment of the present invention, on the basis of the above-mentioned structure, the lightweight paper specified in the present invention is used for the upper paper and the lower paper of the gypsum board base paper, and other than this, it is the same as the actual continuous manufacturing process of the gypsum board. Therefore, as the gypsum slurry used in the manufacturing method of the gypsum board of the present invention, any gypsum slurry for gypsum board known in the past can be used. Below, the gypsum and other components as the constituent materials of the gypsum slurry are briefly described.

[0044] <Plaster of Paris>

[0045] The main component of the gypsum slurry used in the manufacturing method of the gypsum board of the present invention is plaster of Paris. Plaster of Paris is called semi-hydrated gypsum, and there are α-type semi-hydrated gypsum and β-type semi-hydrated gypsum according to the difference in the firing method. α-type semi-hydrated gypsum is manufactured by a wet method, and is obtained by firing dihydrate gypsum in water (including steam). β-type semi-hydrated gypsum is manufactured by a dry method, and is obtained by firing dihydrate gypsum in the atmosphere. The plaster of Paris constituting the gypsum slurry used in the manufacturing method of the present invention can use either α-type semi-hydrated gypsum and β-type semi-hydrated gypsum, and can also be used in combination as appropriate. In addition, α-type semi-hydrated gypsum has the advantages that the amount of water required for curing is less than that of β-type semi-hydrated gypsum, and the strength is high when cured.

[0046] <Other additives>

[0047] In the gypsum slurry used in the manufacturing method of the present invention, in addition to gypsum, other additives known in the past such as setting time regulator, pH regulator, defoamer, etc. can also be contained as needed. For example, as a setting delay agent, citrates such as sodium citrate, succinates, acetates, malates, borates such as borax, sucrose, hexametaphosphate, ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid, starch and protein decomposition products can be used. As a defoamer, general defoamers such as polyether, silicone, alcohol, mineral oil, vegetable oil and nonionic surfactants can be appropriately used.

[0048] Example

[0049] Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, "%" in Examples and Comparative Examples is a mass basis unless otherwise specified.

[0050] <Examples and Comparative Examples>

[0051] Hereinafter, the manufacturing method of the gypsum board of the present invention is described by listing embodiments and comparative examples. The present inventors used the same manufacturing equipment and the same raw materials in a gypsum board production line that is an actual machine operating for the manufacture of ordinary gypsum boards, and further manufactured gypsum boards of the same size of 12.5 mm thick and 910 mm × 1820 mm in size. At this time, the effects of changing the manufacturing conditions on the "wrinkling" of the gypsum board products were studied. Specifically, the effects of changes in the manufacturing speed in the gypsum board production line, the presence or absence of water spraying (coating), the spraying location, the basis weight of the gypsum board base paper, etc. on the "wrinkling" of the obtained gypsum board products were studied. In the evaluation, the gypsum board products obtained from the gypsum board production line were sampled and evaluated according to the following evaluation criteria.

[0052] <Evaluation Method>

[0053] First, the evaluation method for confirming the effect obtained by the manufacturing method of the gypsum board of the present invention is described. Specifically, the "wrinkles" generated in the base paper for the lower paper gypsum board constituting the surface of each gypsum board obtained by the manufacturing method of the gypsum board with various manufacturing conditions changed are evaluated by the following evaluation method.

[0054] (Wrinkle Evaluation Method)

[0055] A representative one was sampled from a gypsum board having a thickness of 12.5 mm and a size of 910 mm×1820 mm which was continuously produced by a common gypsum board production line, and a half of the sample having a size of 910 mm×910 mm was used as a sample for evaluation of wrinkles.

[0056] As a wrinkle evaluation method, a method based on the use of a surface state evaluator described in Japanese Patent Publication No. 59-178306 is used. In this method, the degree of wrinkles is relatively evaluated using the following principle: an ultrasonic wave is irradiated on the object to be tested and its reflected wave is received. If there are many wrinkles, the reflected wave is dispersed and therefore less, and if there are few wrinkles, the reflected wave is not dispersed and is more. Table 1 shows the judgment criteria of the "degree of wrinkling" based on the "difference in the numerical value of the signal level (relative value) of the reflected wave". In this numerical difference, the signal level (relative value) of the reflected wave of the sample in a mirror-like state used in the present invention is set to 100 and divided into 6 stages. In addition, in addition to the difference in the signal level divided into these 6 stages, Table 1 also shows the criteria for identifying the degree of wrinkles based on visual evaluation under oblique light based on the experience obtained by the inventors and others, and the same 6 stages are used.

[0057] The evaluation symbols in Table 1 represent the evaluation criteria obtained by comprehensively judging the evaluation criteria based on the numerical value of the "difference in the numerical value of the signal level (relative value) of the reflected wave" and the sensory evaluation of "visual evaluation under oblique light". In the following test example, the result of evaluating the "wrinkles of the base paper" generated in the manufactured gypsum board is shown as "wrinkle evaluation" as the evaluation symbol. Then, as shown in Table 1, evaluation symbols 1 to 3 are regarded as qualified products with no problems in manufacturing.

[0058] Table 1: Evaluation criteria used in judging wrinkles

[0059] Reflected wave (relative value) Evaluation mark Degree of wrinkling based on visual evaluation 80 and above 1 Pass: Like a mirror, no problem at all. Less than 80 and more than 70 2 Qualified: The wrinkle depth is less than 0.05mm, which is allowed. Less than 70 and more than 60 3 Qualified: The wrinkle depth is less than 0.10mm, which is allowed. Less than 60 and more than 50 4 Unqualified: The wrinkle depth is greater than 0.10mm and less than 0.15mm. Less than 50 and more than 40 5 Unqualified: The wrinkle depth is greater than 0.15mm and less than 0.20mm. Less than 40 6 Unqualified: wrinkle depth is more than 0.2mm.

[0060] [Comparative Example 1 to Comparative Example 3]

[0061] In order to confirm the tendency of "wrinkling" generated in the base paper of gypsum board products, a manufacturing test was conducted by changing the manufacturing conditions in a conventional gypsum board production line as follows. Specifically, first, in a conventional gypsum board production line, the speed of the conveyor belt was changed to 90m / min and 120m / min to perform the manufacturing respectively, and the influence of the speed of the conveyor belt on "wrinkling" was confirmed. In addition, the speed of the conveyor belt was kept constant at 90m / min, and the basis weights of the upper paper (back side of the board) and the lower paper (front side of the board) of the gypsum board base paper used in the manufacturing process were compared with the case of using the same basis weight as in the past, to investigate whether the difference in basis weight would have an effect on "wrinkling". Specifically, for the case of using a base paper with a surface / back=150 / 150 (g / m 2 ) and the case where the base paper with the same basis weight is made as the front / back = 150 / 140 (g / m 2 ) was made so that the basis weight of the upper paper (the back side of the board) was smaller than the basis weight of the lower paper (the front side of the board) to confirm whether the difference in the basis weight of the base paper affects the "wrinkling" of the base paper of the gypsum board. The obtained results are shown in Table 2.

[0062] Table 2: Effect of wrinkling, conveyor speed and basis weight of front and back base papers

[0063]

[0064] As shown in the results of Comparative Examples 1 and 2 shown in Table 2, it was found that the basis weight of the base paper affects the "wrinkling" of the base paper of the manufactured gypsum board, and further found that by using a base paper with a smaller basis weight than the lower paper (the front side of the board) of the gypsum board base paper for the upper paper (the back side of the board) of the gypsum board base paper used in the manufacturing process, it was found that the "wrinkling" on the base paper of the manufactured gypsum board can be suppressed.

[0065] In addition, as shown in the results of Comparative Examples 2 and 3 shown in Table 2, it was confirmed that the speed of the conveyor belt affects the "wrinkling" of the base paper of the manufactured gypsum board, and the higher the speed, the more significant the "wrinkling". This means that in order to suppress the "wrinkling" of the manufactured gypsum board, the speed of the conveyor belt needs to be reduced, which becomes an important issue that has a great impact on the manufacturing efficiency. The purpose of the present invention is to develop a simple and effective method that can suppress the "wrinkling" of the manufactured gypsum board without slowing down the speed of the conveyor belt.

[0066] [Examples 1 to 3, Comparative Example 2]

[0067] In a conventional gypsum board production line, the conveyor belt speed is set to 90 m / min, and the same structure is used, that is, the base paper of the gypsum board product is set to front / back = 150 / 140 (g / m 2) and make the basis weight of the upper paper (back side of the board) smaller than the basis weight of the lower paper (front side of the board), and studied whether it is possible to suppress the "wrinkling" of the base paper by spraying water on the upper paper gypsum board base paper. The water spraying on the upper paper gypsum board base paper is carried out at a position between the configuration position of the molding machine and the configuration position of the rough cutting machine (represented as "position" in the table). ＊ ”), and it is carried out at a position 1 / 4 of the upstream side (molding machine side) of the position between them, that is, at a position close to the molding machine side. Table 3 shows the manufacturing conditions and the evaluation results of "wrinkling" of the manufactured gypsum boards. For comparison, Table 3 also shows Comparative Example 2, which is a gypsum board manufactured under the manufacturing conditions of Examples 1 to 3 except that water is not sprayed, as previously described in Table 2. In addition, the spraying of water in the tests of the present invention was carried out using a water sprayer 5 (spraying device (trade name: ST-5, manufactured by Fuso Seiki Co., Ltd.)).

[0068] Table 3: Relationship between wrinkling, the presence or absence of water spray and the amount of spray

[0069]

[0070] As shown in Table 3, it was found that the "wrinkling" of the gypsum board base paper produced can be significantly suppressed by spraying water on the base paper. In addition, it was confirmed that even if the spray amount of water was as small as 2 g / m 2 It can also suppress the "wrinkling" of the gypsum board base paper.

[0071] [Example 4 to Example 7, Comparative Example 3 to Comparative Example 5]

[0072] In a conventional gypsum board production line, the conveyor belt speed is increased to 120 m / min, and the same structure is set, that is, the base paper of the gypsum board product used in the manufacturing process is set to front / back = 150 / 140 (g / m 2 ) and the basis weight of the upper paper (the back side of the board) was made smaller than the basis weight of the lower paper (the front side of the board), and a manufacturing test for the following study was carried out. That is, the following was confirmed: whether the "wrinkling" of the gypsum board base paper can be suppressed by spraying water on the upper gypsum board base paper during the manufacturing process even when the speed is increased. In addition, the influence of the difference in the position of spraying water on the upper gypsum board base paper or the difference in the amount of water sprayed on the suppression of the "wrinkling" of the gypsum board base paper was studied.

[0073] Table 4 summarizes the manufacturing conditions and the evaluation results of "wrinkling" of the manufactured gypsum boards. As shown in Table 4, in Examples 4 to 7, water was sprayed onto the base paper for the water-upward gypsum board at a position between the configuration position of the molding machine and the configuration position of the rough cutter, and at a position that is 1 / 4 of the upstream side (molding machine side) of the position between the positions, or at a position on the molding machine side that is closer to the upstream (near the front side) than the position of 1 / 4. Specifically, in Examples 4, 6, and 7, water was sprayed at a position of 1 / 4 of the upstream side (molding machine side), and in Example 5, water was sprayed at a position of 1 / 16 that is further upstream (near the front side). In addition, for comparison, Comparative Example 3, which was previously described in Table 2 and in which the gypsum board was manufactured under the manufacturing conditions of Examples 4 to 7 except that water was not sprayed, is also shown in Table 4. In Comparative Examples 4 and 5, water was sprayed at a position on the downstream (further) side than "a position between the position where the molding machine is arranged and the position where the rough cutter is arranged, and a position 1 / 4 of the upstream side (molding machine side) of the position between them" specified in the present invention. Specifically, in Comparative Example 4, water was sprayed at the 3 / 4 position, and in Comparative Example 5, water was sprayed at the 2 / 4 (1 / 2) position.

[0074] Table 4: Relationship between wrinkling, spray water position and spray amount

[0075]

[0076] As shown in Table 4, first, the results of Comparative Examples 3 to 5 confirmed that: when the conveyor speed is as fast as 120 m / min, by spraying water on the upward gypsum board base paper, the "wrinkling" of the gypsum board base paper can be suppressed. However, it can be seen from the comparison between Example 4 and Example 5 and Comparative Examples 4 and 5 that the degree of the effect is different depending on the position where the water is sprayed on the upward gypsum board base paper. As shown in Table 4, it is confirmed that a significant effect can be obtained at the position specified in the present invention "a position between the configuration position of the molding machine and the configuration position of the rough cutting machine, and a position that is 1 / 4 of the upstream side (molding machine side) of the position between them or a position that is upstream of the 1 / 4 position". On the other hand, it is confirmed that: as in Comparative Examples 4 and 5, when water is sprayed at a position that is downstream of the position that is 1 / 4 of the upstream side (molding machine side) specified in the present invention, the effect is poor.

[0077] Furthermore, the present inventors have found that, as shown in Table 4, from the comparison of Example 4, Example 6 and Example 7, it can be seen that for the manufactured gypsum board, when the speed of the conveyor belt is as fast as 120m / min, by spraying water on the base paper under the conditions specified in the present invention, the "wrinkling" of the gypsum board base paper can be significantly suppressed. In addition, based on the comparison of Example 4 and Example 5, it was confirmed that: by spraying water at a position closer to the molding machine, which is "a position between the configuration position of the molding machine and the configuration position of the rough cutting machine, and more upstream than the position 1 / 4 of the upstream side (molding machine side) of the position between these positions", a better effect of suppressing "wrinkling" can be obtained. Regarding the amount of water sprayed, as with the previously confirmed case of setting the conveyor belt speed to 90m / min, it was confirmed that the "wrinkling" can be suppressed at a level as low as 2g / m 2 Even in the case of about 2.5°, the effect of suppressing "wrinkling" of the gypsum board base paper can be obtained.

[0078] [Example 8 to Example 14, Example 4]

[0079] As Examples 9 to 14, in a conventional gypsum board production line, the conveyor speed was increased to 120 m / min, the water spraying condition was set to a constant position of 1 / 4 of the upstream side (molding machine side) specified in the present invention, and the "front / back basis weight" and "front / back basis weight difference" of the base paper of the gypsum board product used in the manufacturing process were changed as shown in Table 5, and the water spraying amount was set to the configuration shown in Table 5, respectively, and a manufacturing test was conducted. In addition, in Example 8, the base weight of the base paper of the gypsum board product used in the manufacturing process was the same without difference, and gypsum board was manufactured under the condition of spraying water on the upper paper at a position of 1 / 16 of the upstream side (molding machine side) which is upstream of the position of 1 / 4 of the upstream side (molding machine side) specified in the present invention and closer to the molding machine, and the obtained gypsum board product was evaluated. In order to compare the manufacturing conditions, the manufacturing conditions and evaluation results of Example 4 shown in Table 4 are also recorded in Table 5.

[0080] Table 5: Relationship between the basis weight of the base paper of wrinkling, front and back and the difference in basis weight

[0081]

[0082] As shown in Table 5, first, from the results of Example 8, it can be confirmed that when the conveyor speed is as fast as 120 m / min, even if there is no difference in the basis weight of the gypsum board base paper of the upper paper (the back side of the board) and the lower paper (the front side of the board), by spraying water on the upper gypsum board base paper at the specific position specified in the present invention, the "wrinkling" of the gypsum board base paper can be suppressed.

[0083] As shown in Table 5, in Example 9, Example 4, and Example 10, gypsum boards were manufactured under the same conditions except that the combination of the gypsum board base paper of the upper paper (backing) and the lower paper (surface) was changed. Specifically, in Example 9, the upper paper (backing) was 145 g / m 2 , bottom paper (top) is 150g / m 2 In this case, the basis weight of the upper paper is 5g / m2 less than that of the lower paper. 2 In Example 4, the upper paper (backing) was 140 g / m 2 , bottom paper (top) is 150g / m 2 In this case, the basis weight of the upper paper is 10g / m2 less than that of the lower paper. 2 In Example 10, the upper paper (backing) was 130 g / m 2 , bottom paper (top) is 150g / m 2 In this case, the basis weight of the upper paper is 20g / m2 less than that of the lower paper. 2 From these evaluation results, it was confirmed that when the difference in basis weight was large, there was a tendency that "wrinkling" could be further suppressed.

[0084] In addition, as shown in Table 5, from the comparison between Example 10 and Example 11, both of which have an evaluation result of "1", it can be seen that by increasing the difference in basis weight between the upper paper and the lower paper of the base paper, the same effect can be obtained even if the amount of water sprayed is reduced. Reducing the amount of water sprayed means that the burden on the drying process caused by spraying water can be reduced, which is useful in terms of manufacturing cost.

[0085] Furthermore, as shown in Table 5, in Examples 12 to 14, gypsum boards were manufactured using lighter gypsum board base paper to examine the applicability of the present invention. Specifically, as the gypsum board base paper, a base paper with a basis weight of 130 g / m 2 The base paper and the upper paper (backing) use 120g / m 2 The base paper has a basis weight difference of 10 g / m 2 Combination. Compared with the previous examples, the above-mentioned lightweight papers used in Examples 12 to 14 are more concerned about "wrinkling". In contrast, as shown in Table 5, it was confirmed that when using lighter base papers such as Examples 12 to 14 to manufacture gypsum boards, it is also possible to suppress "wrinkling" of the base paper for gypsum boards by spraying water at specific positions specified in the present invention. Specifically, as shown in Table 5, it was confirmed that when the spray amount of water was 2 g / m 2 ~200g / m 2In the range of , it is possible to produce a gypsum board that is a qualified product in the evaluation of "wrinkling" of the gypsum board base paper. In addition, if the spray amount of water is 100g / m 2 The above can more stably suppress the "wrinkling" of the gypsum board base paper.

[0086] Description of Reference Numerals

[0087] 1. Base paper for lower gypsum board; 2. Gypsum slurry; 3. Base paper for upper gypsum board; 4. Plate-shaped laminate; 5. Water sprayer (spraying device); 6. Mixer; 10. Conveyor forming belt (conveyor belt); 20. Forming machine; 30. Rough cutting machine; 40. Dryer; 50. Fine cutting machine.

Claims

1. A method for manufacturing a gypsum board, which is a continuous method for manufacturing a gypsum board, the method comprising a molding and conveying step, in which a plate-like laminate is molded and conveyed while the plate-like laminate is molded, the plate-like laminate being formed by laminating gypsum slurry as a raw material of a gypsum material layer of the gypsum board between a base paper for an upper gypsum board and a base paper for a lower gypsum board, characterized in that: The molding and conveying step includes the following series of processes: continuously pouring the gypsum slurry on the lower gypsum board base paper before being continuously fed into the molding machine, laminating the upper gypsum board base paper on the poured gypsum slurry to form a plate-shaped laminated body by the molding machine, and conveying the formed plate-shaped laminated body to a rough cutting machine by a conveyor molding belt, Water is sprayed or applied to the base paper for the upper gypsum board at a position between the configuration position of the molding machine and the configuration position of the rough cutting machine, and at a position 1 / 4 of the upstream side (molding machine side) therebetween, or at a position on the molding machine side upstream of the 1 / 4 position.

2. The method for manufacturing a gypsum board according to claim 1, wherein: The basis weight of the base paper for the upper gypsum board and the basis weight of the base paper for the lower gypsum board are both 80 g / m 2 ~200g / m 2 within the range.

3. The method for manufacturing a gypsum board according to claim 1 or 2, wherein: The basis weight of the base paper for the upper gypsum board is 5 g / m smaller than the basis weight of the base paper for the lower gypsum board. 2 ~60g / m 2 .

4. The method for manufacturing a gypsum board according to claim 1 or 2, wherein: The spraying amount or coating amount of the water is 2.0 g / m 2 ~200g / m 2 within the range.

5. The method for manufacturing a gypsum board according to claim 3, wherein: The spraying amount or coating amount of the water is 2.0 g / m 2 ~200g / m 2 within the range.

6. The method for manufacturing a gypsum board according to claim 1 or 2, wherein: The conveying speed of the conveyor forming belt is above 60 m / min.

7. The method for manufacturing a gypsum board according to claim 3, wherein: The conveying speed of the conveyor forming belt is above 60 m / min.

8. The method for manufacturing a gypsum board according to claim 4, wherein: The conveying speed of the conveyor forming belt is above 60 m / min.

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