JP2016175256A - Method for manufacturing inorganic board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an inorganic board that can simply ensure coating film adhesion while maintaining mold releasability during press-forming.SOLUTION: In a method for manufacturing an inorganic board by press-forming a green sheet composed mainly of a hydraulic material by a molding die and then forming a coating film comprising an aqueous coating material on a surface of a hardened board produced by curing and hardening the green sheet, the method includes allowing a mold release agent to adhere to at least one of a surface of the green sheet and a press surface of the molding die, curing and hardening after press-forming, and performing the modification for imparting hydrophilicity to the surface of the hardened board to which the mold release agent adhered by plasma treatment.SELECTED DRAWING: None

Description

  The present invention relates to a method for manufacturing an inorganic plate.

  The inorganic board used for outer wall materials, roofing materials, etc. is a green sheet mainly composed of a hydraulic material such as cement-based material. It is manufactured by forming a coating film made of a water-based paint or the like. Patent Document 1 discloses that when an inorganic plate is produced, press molding is performed by attaching a release agent to at least one surface of a green sheet or a molding die.

JP 2004-142151 A

  When the green sheet has hydrophilicity, an oil-based release agent (hydrophobic release agent) is used as the release agent. However, there is a problem that even when an aqueous paint is applied to the surface of the cured plate to which the release agent is adhered, the aqueous paint is easily repelled by the hydrophobic release agent, and the coating film is difficult to adhere to the surface of the cured plate. is there.

  On the other hand, when the green sheet has hydrophobicity, a hydrophilic release agent is used as the release agent. However, even if a water-based paint is applied to the surface of the hardened plate to which the release agent is adhered, the water-based paint is easily repelled by the hardened plate, and the portion of the surface where the hardened plate is exposed, that is, the surface of the hardened plate. Since the part to which the release agent is not attached is hydrophobic, there is a problem that the coating film is difficult to adhere.

  For example, as a mold release agent, there is a countermeasure against such a problem of coating film adhesion that a mold release agent that adheres to the surface of the green sheet and penetrates into the green sheet and hardly remains on the surface is used. However, since such a release agent has a low molecular weight, there is a problem that the working environment of press molding tends to be deteriorated.

  On the other hand, a sealer resin having a relatively high affinity with the release agent is applied on the surface of the cured plate to which the release agent is adhered to form a sealer resin layer, and a water-based paint is applied on the sealer resin layer. There is a countermeasure. However, this measure has a problem that the sealer resin is compatible with the release agent, and the release agent is likely to float on the surface of the sealer resin layer, and the adhesion of the coating film is likely to be lowered.

  As described above, there has been a great technical difficulty in securing the coating film adhesion between the cured plate and the coating film made of the water-based coating material while maintaining the releasability during press molding.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing an inorganic plate that can easily ensure adhesion of a coating film while maintaining releasability during press molding. To do.

  The method for producing an inorganic board according to the present invention is to form a coating film made of a water-based paint on the surface of a cured board obtained by press-molding a green sheet mainly composed of a hydraulic material with a mold and then curing and curing. A method of manufacturing an inorganic plate, wherein a release agent is attached to at least one of the surface of the green sheet and the press surface of the mold, and after the press molding is cured and cured, the release agent is attached. The surface of the cured plate is modified to impart hydrophilicity by plasma treatment.

  In the present invention, the release agent has hydrophilicity, while the green sheet has hydrophobicity, and the plasma treatment may modify the surface of the cured plate to hydrophilicity. preferable.

  In the present invention, the hydraulic material is preferably a polymer cement containing a hydrophobic substance.

  In the present invention, it is preferable that the green sheet has hydrophilicity, while the release agent has hydrophobicity, and the release agent is modified to be hydrophilic by the plasma treatment. .

  In the present invention, a hydrophobic layer is formed by penetrating at least a part of the release agent on the surface of the green sheet, and only the surface side of the hydrophobic layer is modified to be hydrophilic by the plasma treatment. It is preferable.

  In the present invention, the plasma treatment is preferably a corona discharge treatment.

  According to the present invention, a release agent is attached to at least one of the surface of the green sheet and the press surface of the mold, and after press molding is cured and cured, the surface of the cured plate to which the release agent is attached is subjected to plasma treatment. Therefore, the coating film adhesion can be easily ensured while maintaining the releasability during press molding.

  Embodiments of the present invention will be described below.

The manufacturing method of the inorganic board of embodiment (henceforth this embodiment) of this invention is the surface of the hardening board obtained by carrying out curing hardening after pressing the green sheet which has a hydraulic material as a main component with a shaping | molding die. In this method, an inorganic plate is produced by forming a coating film made of a water-based paint. At the time of press molding, a release agent is attached to at least one of the surface of the green sheet and the press surface of the mold. Then, curing is performed after press molding, and the surface of the cured plate to which the release agent is attached is modified to impart hydrophilicity by plasma treatment. That is, the manufacturing method of the inorganic board of this embodiment is:
A pressing step (a) for press-molding a green sheet, and a curing step (b) for curing and curing a green sheet (hereinafter sometimes referred to as a molded green sheet) that has been press-molded and has a release agent attached thereto to obtain a cured plate And a plasma treatment step (c) for performing plasma treatment on the surface of the cured plate, and a coating step for forming a coating film on the surface of the cured plate subjected to the plasma treatment (hereinafter sometimes referred to as a plasma-treated cured plate). (D).

{Green sheet}
The green sheet in the present embodiment is not particularly limited as long as the main component is a hydraulic material. For example, a hydrophobic green sheet, a hydrophilic green sheet, or the like can be used.

  Such a green sheet preferably includes, for example, a hydraulic material, an aggregate, and the like, and is manufactured by papermaking, extrusion, casting, or the like.

(Green sheet with hydrophobic properties)
The green sheet having hydrophobicity (hereinafter referred to as hydrophobic green sheet) is a green sheet whose surface has a large contact angle with water and is easy to repel water. For example, the contact angle with water is Preferably it is 90 ° or more, more preferably 110 ° or more. The hydrophobic green sheet preferably includes, for example, a hydraulic material, an aggregate, and the like, and an additive is blended as necessary. Examples of additives include powders such as fly ash, reinforcing fibers such as polypropylene fibers, dispersants, thickeners, extenders, colorants, pigments, viscosity modifiers, and the like. The contact angle with water is measured by the θ / 2 method using a contact angle meter at a temperature of 23 ± 5 ° C. with 1 μL of water dropped on the surface of the hydrophobic green sheet in a horizontal state. be able to.

  As a hydraulic material used for the hydrophobic green sheet, for example, a cement-based material such as Portland cement, fly ash cement, blast furnace cement, alumina cement, high alumina cement, silica fume cement, polymer cement, or the like can be used. These may be used alone or in combination of two or more.

  The polymer cement contains a hydrophobic substance. For example, the polymer cement preferably comprises a cement-containing inverse emulsion composition containing the cement-based material, an oily substance, and water as main components. In this composition, the content of water is preferably 0.3 to 2 parts by mass with respect to the total mass of the cementitious material.

  The hydrophobic substance is not particularly limited as long as it can form an inverse emulsion (W / O emulsion) with water, and usually a hydrophobic liquid substance is used. For example, toluene, xylene, kerosene, styrene, divinyl Examples thereof include benzene, methyl methacrylate, trimethylolpropane trimethacrylate, unsaturated polyester resin, styrene butadiene rubber latex (SBR), ethylene vinyl acetate emulsion (EV), and acrylic emulsion (AE). These may be used alone or in combination of two or more. Preferred are those having a polymerizable double bond (vinyl monomer) such as styrene, divinylbenzene, methyl methacrylate, trimethylolpropane trimethacrylate, and unsaturated polyester resin. As a result, the hydration reaction of the cement-based material and the polymerization reaction of the oily substance having a polymerizable double bond occur at the same time, and the polymer forms a matrix to form an inorganic plate having excellent physical and mechanical properties. Can do. The content of the hydrophobic substance in the cement-containing inverse emulsion composition is not particularly limited, and is preferably 5 to 10% by volume with respect to the total amount of the polymer cement.

  When using a hydrophobic substance having a polymerizable double bond, it is preferable to use a polymerization initiator in combination. Thereby, polymerization of the hydrophobic substance can be promoted. As the polymerization initiator, for example, an organic peroxide such as t-hexylperoxy-2-ethylhexanoate, a persulfate, or the like can be used. Further, a crosslinking agent such as trimethylolpropane trimethacrylate can be used in combination.

  The polymer cement preferably further contains an emulsifier (reverse emulsifier). Thereby, stability can be provided to the inverse emulsion. Examples of the emulsifier include nonionic surfactants such as sorbitan sesquioleate, glycerol monostearate, sorbitan monooleate, diethylene glycol monostearate, sorbitan monostearate, diglycerol monooleate, various anionic surfactants, and cationic systems. A surfactant or the like can be used. The content of the emulsifier is preferably 1 to 3% by volume with respect to the total amount of the polymer cement.

  Aggregates used in hydrophobic green sheets include, for example, natural aggregates such as sand, gravel, and coal ash, molten aggregates, crushed stones, crushed sand, artificial aggregates such as fly ash, etc. Recycled aggregates, lightweight aggregates such as perlite can be used. These may be used alone or in combination of two or more. The blending ratio of the aggregate is preferably 40 to 70 parts by mass with respect to the total mass of the hydraulic material.

(Green sheet with hydrophilicity)
A hydrophilic green sheet (hereinafter referred to as a hydrophilic green sheet) is a green sheet whose surface has a small contact angle with water and easily penetrates water. For example, a contact angle with water. Is preferably 80 ° or less, more preferably 70 ° or less. The hydrophilic green sheet includes, for example, a hydraulic material, an aggregate, and a reinforcing fiber, and an additive is preferably blended as necessary. Examples of additives include powders such as fly ash, dispersants, thickeners such as methylcellulose, weight materials, colorants, pigments, viscosity modifiers, and the like. The contact angle with water is measured by the θ / 2 method using a contact angle meter at a temperature of 23 ± 5 ° C. with 1 μL of water dropped on the surface of the hydrophilic green sheet in a horizontal state. be able to.

  Examples of the hydraulic material used for the hydrophilic green sheet include Portland cement, fly ash cement, blast furnace cement, alumina cement, high alumina cement, and silica fume cement. These may be used alone or in combination of two or more. However, the cement raw material may contain additives in advance.

  Examples of the aggregate used for the hydrophilic green sheet include, for example, natural aggregates such as siliceous materials, sand, gravel, coal ash, artificial aggregates such as molten slag, crushed stone, crushed sand, and fly ash that are fired at high temperature, Lightweight aggregates such as recycled aggregates and microballoons taken out from the concrete waste can be used. These may be used alone or in combination of two or more. As the siliceous material, for example, silica powder, silica powder, silica fume, shirasu balloon, perlite, mica, diatomaceous earth, dolomite, wollastonite, glass powder, siliceous clay, bentonite and the like can be used.

  Examples of reinforcing fibers used for hydrophilic green sheets include vinylon fibers, polyester fibers, polyamide fibers, acrylic fibers, acetate fibers, polyethylene fibers, polypropylene fibers, and other organic fibers, glass fibers, carbon fibers, ceramic fibers, and metal fibers. Etc. can be used. These may be used alone or in combination of two or more. The fiber length of the reinforcing fiber is not particularly limited, and is preferably 0.5 to 10 mm, more preferably 2 to 8 mm. The fiber diameter of the reinforcing fiber is not particularly limited, and is 1 to 100 μm, more preferably 10 to 30 μm.

{Pressing process (a)}
In the pressing step (a), a mold is used to attach a release agent to at least one of the surface of the green sheet and the pressing surface of the mold, and the green sheet is press-molded. Thereby, while the surface shape (uneven shape) of a press surface is transcribe | transferred on the surface of a green sheet, the shaping | molding green sheet in which the thickness of the green sheet was formed in the predetermined product thickness is obtained. Furthermore, by attaching a release agent to at least one of the surface of the green sheet and the press surface of the mold, the green sheet can be easily released during press molding.

(Release agent)
The release agent is not particularly limited, and for example, a hydrophobic release agent (hereinafter referred to as a hydrophobic release agent), a hydrophilic release agent (hereinafter referred to as a hydrophilic release agent), or the like is used. Can do. When a hydrophobic green sheet is used as the green sheet, it is preferable to use a hydrophilic release agent. Moreover, when using a hydrophilic green sheet as a green sheet, it is preferable to use a hydrophobic release agent.

  The hydrophobic release agent is, for example, natural fats and oils, synthetic oils, or a mixture of both. Specifically, oil-based mold release agents such as synthetic oils such as silicon oil, fluoride, and hydrocarbons, and refined petroleum products such as kerosene, light oil, spindle oil, and machine oil can be used. These may be used alone or in combination of two or more.

  The hydrophilic release agent is, for example, a water-soluble resin or a surfactant. These may be used alone or in combination of two or more.

  Examples of the method for applying the release agent include a dipping method, a brush coating method, a roller coating method, a spray method, a flow coating, and a rotary coating.

The application amount of the release agent is not particularly limited, and is preferably 5 to 50 g / m ² , more preferably 5 to 20 g / m ² .

In particular, when a hydrophilic green sheet is used as the green sheet and a hydrophobic release agent is used as the release agent, the coating amount of the release agent is preferably 5 to 20 g / m ² , more preferably 5 to 10 g / m ² . is there. Thereby, at least a part of the hydrophobic release agent penetrates into the surface of the hydrophilic green sheet to form a hydrophobic layer. That is, the hydrophobic layer is composed of a layer made of a hydrophobic release agent located on the surface of the hydrophilic green sheet and a layer made of a hydrophobic release agent that has penetrated into the hydrophilic green sheet. And after curing and curing this hydrophilic green sheet, only the hydrophobic side of the surface of the hydrophobic layer is modified to be hydrophilic by plasma treatment, which will be described later. It remains unmodified by plasma treatment. Therefore, the obtained inorganic board has a water-repellent layer derived from a part of the hydrophobic release agent that is not modified to be hydrophilic. As a result, it can be set as the inorganic board excellent in water permeability.

  Examples of the forming method include a method in which a forming die is arranged above the green sheet, the forming die is lowered toward the green sheet in this state, and the green sheet is pressed. The press pressure is not particularly limited, and is preferably 1 to 10 MPa. What is necessary is just to adjust the uneven | corrugated shape of a press surface suitably according to the use application of an inorganic board.

{Curing process (b)}
In the curing step (b), the molded green sheet is cured and cured to obtain a cured plate with a release agent attached thereto.

  Examples of the curing method include a method in which a primary curing is performed on a formed green sheet and a certain degree of strength is secured, and then a secondary curing (autoclave curing) is performed.

  The primary curing may be appropriately adjusted according to the material of the hydraulic material, and examples thereof include normal temperature curing and steam curing. Specifically, the primary curing is preferably performed, for example, at a temperature of 40 to 90 ° C. for 4 to 12 hours under normal pressure.

  The autoclave curing may be appropriately adjusted according to the primary curing conditions, the material of the hydraulic material, and the like, for example, performed at a temperature of 160 to 180 ° C. for 4 to 12 hours under 5065 to 8104 hPa (5 to 8 atm). Is preferred.

{Plasma treatment step (c)}
In the plasma treatment step (c), the surface of the cured plate to which the release agent is attached is modified to impart hydrophilicity by plasma treatment. Thereby, even if a water-based paint is applied to the surface of the plasma-treated cured plate, the water-based paint is hardly repelled. That is, the surface of the cured plate to which the release agent is attached can be modified to be hydrophilic by a relatively simple method called plasma treatment, and the adhesion of a coating film made of an aqueous paint can be ensured. The hydrophilicity is imparted in this way because, for example, a resin component such as a hydrophobic release agent or a hydrophobic substance located on or near the surface of the cured plate is exposed to the plasma discharge region by the plasma treatment, It is presumed that a carboxyl group, a hydroxyl group, a carbonyl group or the like is generated.

  When a curing plate having hydrophobicity obtained by curing and curing a hydrophobic green sheet as a curing plate (hereinafter sometimes referred to as a hydrophobic curing plate), when using a hydrophilic release agent as a release agent, by plasma treatment, The surface of the hydrophobic cured plate is modified to be hydrophilic. Thereby, even if it is a case where a hydrophobic cured board is used as a cured board, the adhesiveness of the cured board and the coating film which consists of water-based paints can be ensured by a comparatively simple method.

  In addition, when a curing plate having hydrophilicity (hereinafter sometimes referred to as a hydrophilic curing plate) obtained by curing and curing a hydrophilic green sheet is used as the curing plate, and when a hydrophobic release agent is used as the release agent, plasma treatment is performed. As a result, the hydrophobic release agent is modified to be hydrophilic. This makes it easy to release the hydrophilic cured plate during press molding with the hydrophobic release agent, while the hydrophilic release property is imparted to the hydrophobic release agent by surface modification. Adhesiveness with the coating film consisting of can be ensured.

  Examples of plasma treatment include plasma treatment under atmospheric pressure, plasma treatment under vacuum, corona discharge treatment, plasma flame treatment, and excimer lamp treatment. Among them, corona that can perform plasma treatment relatively easily. Discharge treatment is preferred.

(Corona discharge treatment)
Corona discharge treatment imparts hydrophilicity to the surface of the cured plate by generating corona discharge in the atmosphere using a high-frequency power supply voltage and irradiating the surface of the cured plate with electrons and ions generated along with it. It is. Such hydrophilicity is given, for example, by molecules containing oxygen generated by corona discharge treatment, and resin components such as a hydrophobic release agent and a hydrophobic substance located on the surface of the cured plate or in the vicinity thereof. This is presumed to be due to the formation of carboxyl group, hydroxyl group, carbonyl group and the like.

Although there is no restriction | limiting in particular as a discharge amount in the case of a corona discharge process, Preferably it is 1-15 kW * min / m < ² >, More preferably, it is 5-10 kW * min / m < ² >. The discharge amount is calculated from the following formula (1).
Discharge amount = discharge power / (treatment speed × electrode length) (1)

  For example, after placing a hardened plate on a conveyor and using a corona discharge treatment device (“PSCMECHA” manufactured by Pearl Industry Co., Ltd.) under the following conditions by the corona discharge method (in air), The moving speed (processing speed) is preferably 5 to 15 m / min, more preferably 5 to 10 m / min. When the treatment speed is within the above range, the surface of the cured plate can be more sufficiently modified and the productivity is more excellent.

(Example of corona discharge treatment conditions)
・ Oscillation frequency: 20 kHz
・ Method: Air corona blowout ・ Pulse frequency: 100 kHz
・ Workpiece distance: 10mm
-Number of processing: 1 time.

{Coating process (d)}
In the coating step (d), a coating film is formed on the surface of the plasma-treated cured plate. Thereby, the inorganic board excellent in coating-film adhesiveness is obtained.

  The configuration of the coating film is not particularly limited, and may be a single layer, or may be a two-layer configuration including an undercoat layer made of an undercoat water-based paint and an overcoat layer made of an overcoat water-based paint. A multi-layer structure of three or more layers may be used.

  The thickness of the coating film is preferably 20 to 50 μm.

  The coating film is formed, for example, by applying an aqueous paint on the surface of the plasma-treated cured plate and drying it. In the case where the coating film has a two-layer structure, for example, an undercoat water-based paint is applied on the surface of the plasma-treated cured plate and dried to form an undercoat layer, and then the surface of the obtained undercoat layer is formed. It is formed by applying a top-coat water-based paint and drying it.

The application amount of the water-based paint is preferably 40 to 200 g / m ² · wet, more preferably 150 to 200 g / m ² · wet.

When the coating film has a two-layer structure, the coating amount of the undercoat water-based paint is preferably 50 to 150 g / m ² · wet, more preferably 80 to 120 g / m ² · wet. , Preferably 80 to 200 g / m ² · wet, more preferably 120 to 150 g / m ² · wet.

  The method for applying the water-based paint is not particularly limited, and examples thereof include a spray gun, a roll coater, a flow coater, and a curtain coater.

(Water-based paint)
As the water-based paint, for example, an acrylic resin paint based on an acrylic emulsion, an acrylic silicon resin paint based on an acrylic silicon emulsion, or the like can be used. It is preferable that at least one of extender pigment and hygroscopic resin is blended in the water-based paint. Thereby, color developability can be improved.

  Examples of extender pigments that can be used include silica, alumina, aluminum hydroxide, calcium carbonate, barium sulfate, porous silica, and diatomaceous earth. As the hygroscopic resin, for example, an ink-absorbing polymer such as vinyl acetate, urethane polymer, acrylic polymer, polyvinyl alcohol, or the like can be used. In addition, pigments such as titanium oxide, iron oxide, and carbon black can be blended in the water-based paint as a colorant.

  As the undercoat water-based paint and the topcoat water-based paint, those exemplified as the water-based paint can be used.

  Hereinafter, the present invention will be specifically described by way of examples.

(Release agent)
Release agents A to D shown in Table 1 were used.

(Water-based paint)
-Undercoat water-based paint: A water-based Mighty Sealer Multi manufactured by Dainippon Paint Co., Ltd. was mixed with water.
-Top coat water-based paint: A product obtained by mixing "View Silicon" manufactured by Dainippon Paint Co., Ltd. with water.

  Moreover, using the green sheet obtained through the pressing step (a), the cured plate after the plasma treatment step (c), and the inorganic plate obtained through the coating step (d), Evaluation of releasability, water repellency, and coating film adhesion was performed. The evaluation method is as follows.

(Evaluation of releasability)
The releasability was evaluated in the following two stages based on visual confirmation of the presence or absence of deposits on the surface of the press mold.
○: No deposit other than mold release agent ×: Deposit other than mold release agent (Evaluation of water repellency)
Water was sprayed on the surface of the plasma-treated cured plate by spraying, and relative evaluation was performed according to the shape of the attached water droplets. The evaluation criteria are as follows.
○: Wet uniformly △: Some parts are not repelled and wet ×: All are polka dots (Evaluation of coating film adhesion)
The treatment of air drying at 60 ° C. for 8 hours and then air-drying for 16 hours is one cycle. One cloth tape (“cloth tape” manufactured by Sekisui Chemical Co., Ltd.) is applied to the coating surface of the inorganic board that has been subjected to 10 cycles. I stuck the sheets. Next, the surface of the pasted cloth tape was rubbed 30 times with silicon rubber, and then pulled in the direction of about 45 ° toward the front to peel the cloth tape from the coating surface. The area of the coating film adhering to the adhesive surface of the peeled cloth tape was calculated, and the peeled area ratio was calculated from the following formula (2) using this area. Based on this peeled area ratio, the following three stages were evaluated.
Peeling area ratio (%) = (Area of coating film adhered to adhesive surface of peeled fabric tape / Area of adhesive surface of fabric tape) × 100 (2)
○: Peeling area ratio <1%
Δ: 1% ≤ peeling area ≤ 3%
X: 3% <peeling area ratio

[Example 1, Comparative Example 5]
(Production of polymer cement board)
As molding materials, Portland cement 44.15 parts by mass, fly ash 30.0 parts by mass, oily substance (styrene) 4.5 parts by mass, lightweight aggregate (perlite) 18.5 parts by mass, polypropylene fiber 1.2 parts by mass , 1.5 parts by weight of an emulsifier (sorbitan monooleate), 0.05 parts by weight of a crosslinking agent (trimethylolpropane trimethacrylate), 0.1 parts by weight of a polymerization initiator (t-hexylperoxy-2-ethylhexanoate) A cement-containing inverse emulsion composition comprising 100 parts by mass of the solid content and 43.0 parts by mass of water was put into an extruder and extruded from a die member to obtain a polymer cement plate (hydrophobic green sheet). The size of the green sheet was 0.5 m × 0.5 m × 0.2 mt. The contact angle of the polymer cement board with water was 97 °.

(Pressing process (a))
The release agent shown in Table 2 was applied on the press surface of the molding machine by spraying. At this time, the coating amount of the release agent was 20 g / m ² . Next, the green sheet was press-molded under the condition of 1 MPa to obtain a green sheet (molded green sheet) with a release agent attached thereto. When the surface of the molded green sheet was visually observed, the entire surface was not covered with a release agent, and there was a portion where the green sheet was exposed.

  Using the obtained molded green sheet, the releasability was evaluated. The results are shown in Table 2.

(Curing process (b))
The molded green sheet was cured and cured under normal pressure at a temperature of 100 ° C. for 10 hours and dried to obtain a cured plate (hydrophobic cured plate) with a release agent attached thereto.

(Plasma treatment step (c))
After the hydrophobic cured plate is placed on the conveyor, the moving speed (processing speed) of the conveyor is adjusted to the speed shown in Table 2, corona discharge treatment is performed on one side of the hydrophobic cured plate, and the plasma-treated cured plate is Obtained. The obtained plasma-treated cured plate was evaluated for water repellency. The results are shown in Table 2.

The corona discharge treatment was performed under the following conditions by a corona discharge method (in air) using a corona discharge treatment apparatus (“PSCMECHA” manufactured by Pearl Industry Co., Ltd.).
-Oscillation frequency: 20 kHz.
・ Method: Air blow-out corona.
-Pulse frequency: 100 kHz.
-Work distance: 10 mm.
-Number of processing: 1 time.

(Coating process (d))
On the surface of the plasma-treated cured plate that has been subjected to the corona discharge treatment, an undercoat water-based paint is applied by spraying, and dried at a temperature of about 100 ° C. for about 5 minutes using a hot air dryer. Formed. Next, the top coat water-based paint was applied by spraying and dried at a temperature of about 100 ° C. for about 5 minutes using a hot air drier to form a top coat film to obtain an inorganic plate. The thickness of the lower coating film was 20 μm. The thickness of the top coating film was 10 μm. About the obtained inorganic board, coating-film adhesiveness was evaluated. The results are shown in Table 2.

[Examples 2-6, Comparative Examples 1-4]
(Production of fiber cement board)
As molding materials, Portland cement 65.0 parts by mass, silica powder 13.0 parts by mass, fly ash 12.0 parts by mass, lightweight aggregate (microballoon) 5.0 parts by mass, pulp fiber 1.5 parts by mass, weight increase 5.0 parts by weight of the agent (cured product of the cured plate), 0.3 parts by weight of the thickener (methylcellulose) and 0.2 parts by weight of the dispersant are dry-mixed, and the solid content concentration is 80% by weight. A hydraulic material was obtained by blending water and mixing and dispersing them with a mixer. The obtained hydraulic material was put into an extruder and extruded from a die member to obtain a fiber cement board (hydrophilic green sheet). The contact angle of the fiber cement board with water was 63 °.

(Pressing process (a))
Except for using the release agent shown in Table 2, the green sheet was press-molded in the same manner as in [Example 1, Comparative Example 5] to obtain a green sheet (molded green sheet) to which the release agent adhered. . When the surface of the molded green sheet was visually observed, the entire surface was not covered with a release agent, and there was a portion where the green sheet was exposed.

  Using the obtained molded green sheet, the releasability was evaluated. The results are shown in Table 2.

(Curing process (b))
The molded green sheet was cured and cured in the same manner as in [Example 1, Comparative Example 5] and dried to obtain a cured plate (hydrophilic cured plate) to which the release agent was adhered.

(Plasma treatment step (c))
Except having adjusted the process speed to the speed shown in Table 2, it carried out similarly to [Example 1, the comparative example 5], the corona discharge process was performed to the single side | surface of the hydrophilic cured board, and the plasma-treated cured board was obtained. The obtained plasma-treated cured plate was evaluated for water repellency. The results are shown in Table 2.

(Coating process (d))
On the surface of the plasma-treated cured plate on the side subjected to the corona discharge treatment, a coating film was formed in the same manner as in [Example 1, Comparative Example 5] to obtain an inorganic plate. About the obtained inorganic board, coating-film adhesiveness was evaluated. The results are shown in Table 2.

  In Examples 1 to 6, after the release agent was attached to the pressing surface of the mold in the pressing step (a) and the pressing step (a) and the curing step (b) were performed in this order, the plasma treatment step ( In c), since the surface of the cured plate to which the release agent was adhered was modified by imparting hydrophilicity by plasma treatment, in the evaluation of release property, water repellency and coating film adhesion, There were three, or two “◯” and one “Δ”. That is, in Examples 1 to 6, it was possible to easily ensure the coating film adhesion while maintaining the releasability during press molding.

  On the other hand, in Comparative Examples 1 to 5, after the release agent is adhered to the press surface of the mold in the pressing step (a) and the pressing step (a) and the curing step (b) are performed in this order, plasma treatment is performed. In the step (c), since the surface of the cured plate to which the release agent was attached was not modified to impart hydrophilicity by plasma treatment, in the evaluation of releasability, water repellency and coating film adhesion, One or more “x” was included, or two “Δ” were included. That is, in Comparative Examples 1 to 5, it was not possible to easily ensure the coating film adhesion while maintaining the release property during press molding.

Claims (6)

A method for producing an inorganic board by forming a coating film made of an aqueous paint on the surface of a cured board obtained by press-molding a green sheet mainly composed of a hydraulic material and then curing and curing the green sheet. ,
A release agent is attached to at least one of the surface of the green sheet and the press surface of the mold,
A method for producing an inorganic plate, characterized in that after the press molding is cured and cured, the surface of the cured plate to which the release agent is adhered is modified to impart hydrophilicity by plasma treatment. In the manufacturing method of the inorganic board of Claim 1,
While the release agent has hydrophilicity, the green sheet has hydrophobicity,
The method for producing an inorganic plate, wherein the surface of the cured plate is modified to be hydrophilic by the plasma treatment. In the manufacturing method of the inorganic board of Claim 2,
The method for producing an inorganic board, wherein the hydraulic material is a polymer cement containing a hydrophobic substance. In the manufacturing method of the inorganic board of Claim 1,
While the green sheet has hydrophilicity, the mold release agent has hydrophobicity,
The method for producing an inorganic plate, wherein the release agent is modified to be hydrophilic by the plasma treatment. In the manufacturing method of the inorganic board of Claim 4,
An inorganic material characterized in that a hydrophobic layer is formed by penetrating at least a part of the release agent on the surface of the green sheet, and only the surface side of the hydrophobic layer is modified to be hydrophilic by the plasma treatment. A manufacturing method of a board. In the manufacturing method of the inorganic board of any one of Claims 1 thru | or 5,
The method for producing an inorganic plate, wherein the plasma treatment is a corona discharge treatment.