JP2006062256A - Manufacturing method of inorganic board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an inorganic board, capable of preventing both the generation of efflorescence and the generation of blocking at the time of the autoclave curing. <P>SOLUTION: A hydraulic material mainly composed of cement is molded to prepare a green sheet, and this green sheet is subjected to the autoclave curing to produce the inorganic board. In producing the inorganic board as mentioned in the above, a sealer is coated on the surface of the green sheet into a film thickness of 2-5 μm and then the autoclave curing is conducted in the state wherein a plurality of the green sheets are piled up. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a cement-based inorganic board used for building materials and the like.

  The cement-based inorganic board is prepared by blending aggregates and fibers as necessary with a hydraulic material mainly composed of cement, and forming the green sheet by wet papermaking or the like. And it is manufactured by curing this green sheet in an autoclave. Thus, by autoclaving the green sheet, a high-quality inorganic plate excellent in dimensional stability and strength can be obtained.

However, when autoclave curing is performed in this way, efflorescence is likely to occur, and the surface of the product becomes uneven, and the adhesion of the coating film applied to the surface of the product is deteriorated and peeling is likely to occur. There is a problem. Eflorescence occurs when free lime generated by the hydrolysis of cement elutes into the water and comes to the surface. Therefore, a sealer made of an aqueous resin dispersion such as an acrylic emulsion is placed on the green sheet before autoclaving. It is applied to the surface, and this sealer prevents free lime from eluting into moisture during autoclave curing, thereby preventing the occurrence of efflorescence (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 06-286676

  Here, the autoclave curing is performed in a state where several tens of green sheets are stacked. And when a sealer such as acrylic emulsion is applied before curing the autoclave as described above, the sealer adheres to the overlapping surface of the green sheets stacked up and down during the autoclave curing, and the inorganic plate obtained by autoclaving the green sheet May stick to each other and block the inorganic plate from being peeled off from the stacked state. In particular, blocking is likely to occur when the number of stacked green sheets during autoclave curing is increased, so that blocking is prevented from occurring by reducing the thickness of the sealer coating. However, when the coating thickness of the sealer becomes too thin, it is difficult to prevent the occurrence of efflorescence.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a method for producing an inorganic board that can prevent both efflorescence and blocking during autoclave curing. It is.

  The method for producing an inorganic board according to claim 1 of the present invention is to produce a green sheet by molding a hydraulic material mainly composed of cement, and to produce an inorganic board by curing this green sheet by autoclave. After the sealer is applied to the surface of the sheet with a film thickness of 2 to 5 μm, autoclave curing is performed with a plurality of green sheets stacked.

  Thus, by adjusting the film thickness of the sealer applied on the surface of the green sheet to be in the range of 2 to 5 μm, it is possible to prevent occurrence of blocking while preventing occurrence of efflorescence. It is possible to prevent both occurrence of efflorescence and blocking.

  The invention of claim 2 is characterized in that, in claim 1, variation in coating film thickness of the sealer applied to the green sheet is within 2 μm.

  According to the present invention, it is possible to more reliably prevent occurrence of efflorescence and occurrence of blocking.

  According to the present invention, by adjusting the film thickness of the sealer applied to the surface of the green sheet in the range of 2 to 5 μm, it is possible to prevent occurrence of blocking while preventing occurrence of efflorescence. Can do. Therefore, it is possible to prevent both efflorescence and blocking during autoclave curing.

  Hereinafter, the best mode for carrying out the present invention will be described.

  Hydraulic materials are usually prepared as a slurry by containing cement such as Portland Sent or fly ash cement as a main component, and adding aggregates or fibers as necessary, and mixing them with water. . The mixing ratio of the solid content in the hydraulic material is preferably adjusted so that the cement is 70 ± 10 mass%, the aggregate is 20 ± 5 mass%, and the fiber is 10 ± 5 mass%. And a green sheet can be shape | molded by carrying out wet papermaking etc. of this hydraulic material.

  Prior to autoclaving the green sheet thus formed, a sealer is applied to the surface of the green sheet. The sealer is not particularly limited, and an aqueous emulsion in which the dispersoid is resin colloidal particles and the dispersion medium is water, such as an acrylic resin aqueous emulsion, can be used.

  The sealer can be applied to the surface of the green sheet by spraying. However, when the sealer is applied using a fixed spray device to which a spray gun is fixed, the sealer formed on the surface of the green sheet is applied. The film thickness varies greatly as shown in FIG. Thus, when the variation in the film thickness of the sealer is large, it is difficult to control the film thickness of the sealer within a predetermined range. Therefore, in the present invention, it is preferable to apply the sealer using a rotary spray device.

  FIG. 3 is a plan view showing an example of the rotary spray device. In the rotary spray device, support rods 2 are provided radially at the lower end portion of the rotary shaft 1 arranged vertically, and an annular support 3 is formed by the support rods 2. A plurality of downward spray guns 4 are provided on the support 3 at regular intervals. The rotating shaft 1 is located at the center of the support body 3, and the support body 3 is rotated in the circumferential direction on a horizontal plane by driving the rotating shaft 1 to rotate horizontally. The support 3 is formed with a diameter larger than the width of the green sheet 5. And while rotating the support body 3 of this rotary spray apparatus horizontally, the green sheet 5 is sent in the longitudinal direction at a predetermined speed just below it, and the sealer is sprayed downward from each spray gun 4 to the surface of the green sheet 5. A sealer can be applied. In this way, when the sealer is sprayed while the support 3 is rotated horizontally and the spray gun 4 is moved, each of the plurality of spray guns 4 provided on the support 3 sequentially turns the green sheet 5 across the green sheet 5 in the width direction. The sealer can be sprayed on the surface of the green sheet, and the sealer is uniformly applied to the surface of the green sheet 5 to reduce the variation in the film thickness of the coating film of the sealer formed on the surface of the green sheet 5. (See FIGS. 1 (a) and 1 (b)).

  Thus, after apply | coating the sealer on the surface of a green sheet, the coating film of a sealer can be formed on the surface of a green sheet by heating and drying for about 2 minutes at the temperature of about 100-160 degreeC. Yes, the sealer film may be formed on at least the surface of the green sheet which is the product surface. In the present invention, the film thickness is set so that the film thickness of the sealer coating film formed on the surface of the green sheet is in the range of 2 to 5 μm. In order to control the film thickness of the sealer so as not to deviate from the film thickness in the range of 2 to 5 μm, it is effective to use the rotary spray device described above.

  In this way, multiple sheets (several tens) of green sheets coated with a sealer are introduced into the autoclave chamber in a stacked state, and the green sheets are cured in autoclave under saturated steam at high temperature and pressure to harden the cement. By making it, an inorganic board can be obtained. The conditions for the autoclave curing are not particularly limited, but are preferably set to a temperature of 160 to 170 ° C. and a time of about 3 to 6 hours.

  Thus, in the inorganic board obtained by curing the green sheet by autoclave, the sealer is applied to the green sheet, so that the free lime is prevented from eluting into the moisture and coming out to the surface, and the efflorescence is It can be prevented from occurring. Here, when the coating thickness of the sealer applied to the green sheet is less than 2 μm, the effect of preventing efflorescence by the sealer becomes insufficient, and efflorescence may occur. If the thickness of the sealer applied to the green sheet exceeds 5 μm, the effect of preventing efflorescence is sufficient, but blocking may occur. Therefore, by setting the film thickness of the sealer formed on the surface of the green sheet before curing the autoclave in the range of 2 to 5 μm, it is possible to prevent both efflorescence and blocking.

  Here, the effect of preventing the occurrence of both efflorescence and blocking can be obtained more reliably as the variation in the thickness of the sealer coating film formed on the surface of the green sheet is smaller. The film thickness variation is preferably within 2 μm.

  Next, the present invention will be specifically described with reference to examples.

Example 1
40 parts by mass of cement, 40 parts by mass of fly ash, 10 parts by mass of quartzite powder, 10 parts by mass of pulp, 3 parts by mass of mica, and 10 parts by mass of scrap crushed cement board are mixed with water and solid content concentration A 13% by mass cementitious slurry was prepared. This cementitious slurry was made into a green sheet having a water content of 35% by mass and a thickness of 15 mm.

  On the other hand, as the sealer, “YJ1116MDap” (acrylic resin aqueous emulsion, solid content 50 mass%) manufactured by BASF and water were mixed and diluted at a mass ratio of 1: 3. Then, this sealer was applied to the surface of the green sheet using the rotary spray device of FIG. 3, and then dried by heating at 130 ° C. for 2 minutes. Thus, when the film thickness of the sealer formed on the surface of the green sheet was measured, it was distributed in a range of 3 to 5 μm as shown in FIG.

  Next, 60 sheets of this green sheet were loaded and autoclaved under a saturated water vapor of 164 ° C. and 588 kPa for 4.5 hours, whereby an inorganic material having a plate size of 455 mm × 3030 mm × 15 mm and a specific gravity of 1.0 I got a plate.

(Example 2)
As the sealer, “YJ1116MDap” manufactured by BASF (acrylic resin aqueous emulsion, solid content: 50% by mass) and water were mixed at a mass ratio of 1: 4 and diluted. Other than this, the sealer was applied to the surface of the green sheet and dried using the rotary spray device of FIG. 3 in the same manner as in Example 1. Thus, when the film thickness of the sealer formed on the surface of the green sheet was measured, it was distributed in a range of 2 to 4 μm as shown in FIG.

  Next, 90 sheets of this green sheet were loaded and autoclave-cured in the same manner as in Example 1 to obtain an inorganic plate.

(Comparative Example 1)
As the sealer, “YJ1116MDap” (acrylic resin aqueous emulsion, solid content 50 mass%) manufactured by BASF and water were mixed at a mass ratio of 1: 1 and diluted. Other than this, the sealer was applied to the surface of the green sheet and dried using the rotary spray device of FIG. 3 in the same manner as in Example 1. Thus, when the film thickness of the sealer formed on the surface of the green sheet was measured, it was distributed in the range of 5 to 7 μm as shown in FIG.

  Next, 60 sheets of this green sheet were loaded, and autoclave curing was performed in the same manner as in Example 1 to obtain an inorganic plate.

(Comparative Example 2)
As the sealer, "YJ1116MDap" manufactured by BASF (acrylic resin aqueous emulsion, solid content 50 mass%) and water were mixed at a mass ratio of 1: 5 and diluted. Other than this, the sealer was applied to the surface of the green sheet and dried using the rotary spray device of FIG. 3 in the same manner as in Example 1. Thus, when the film thickness of the sealer formed on the surface of the green sheet was measured, it was distributed in the range of 1 to 3 μm as shown in FIG.

  Next, 60 sheets of this green sheet were loaded, and autoclave curing was performed in the same manner as in Example 1 to obtain an inorganic plate.

  About said Example 1-2 and Comparative Examples 1-2, generation | occurrence | production of efflorescence and generation | occurrence | production of blocking were test | inspected. The results are shown in Table 1. In Table 1, “◯” indicates no occurrence, and “x” indicates occurrence.

  As can be seen from Table 1, neither the efflorescence nor the blocking occurred in Examples 1 and 2 in which the film thickness of the sealer was set in the range of 2 to 5 μm. In particular, in Example 2, blocking did not occur even when the number of stacked sheets was 90 sheets. On the other hand, blocking occurs in Comparative Example 1 where the sealer film thickness deviates from the range of 2 to 5 μm, and efflorescence occurs in Comparative Example 2 where the sealer film thickness deviates from the range of 2 to 5 μm. It was a thing.

It is a graph which shows distribution of the film thickness of the sealer given before autoclave curing, (a) relates to Example 1, and (b) relates to Example 2. It is a graph which shows the distribution of the film thickness of the sealer given before autoclave curing, (a) relates to Comparative Example 1, and (b) relates to Comparative Example 2. It is a top view of a rotary spray device. It is a graph which shows an example of distribution of the film thickness of the sealer given before autoclave curing.

Claims (2)

  A green material is formed by molding a hydraulic material mainly composed of cement, and a sealer is applied to the surface of the green sheet with a film thickness of 2 to 5 μm in order to produce an inorganic plate by curing the green sheet. Then, the manufacturing method of the inorganic board characterized by carrying out an autoclave curing in the state which accumulated several green sheets.   The method for producing an inorganic board according to claim 1, wherein the coating thickness variation of the sealer applied to the green sheet is within 2 μm.

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