JPS61287477A - Formation of inorganic coating film - Google Patents

Abstract

PURPOSE:To obtain coated film having superior gloss and smoothness by applying undercoat comprising aq. soln. of water-soluble alkali silicate contg. powdery solid on a substrate, and applying further aq. soln. of water-soluble alkali silicate contg. no solid on the coated film. CONSTITUTION:An undercoat comprising water-soluble alkali silicate or modified water-soluble alkali silicate, contg. powder solid is applied to a substrate. Obtd. coated film is heated at 1-10 deg.C/min (in average) elevating rate of surface temp., held at 40-150 deg.C to dry until the final water content of the whole coated film attains 1-10wt%. Aq. soln. of water-soluble alkali metal silicate or modified product thereof contg. no powdery solid or contg. less powdery solid than the above-decribed paint is applied to the above-described coated film and the whole coated film is dried by heating at 1-10 deg.C/min (in average) elevating rate of the surface temp., maintaining at 40-150 deg.C until the final water content of the whole coated film attains 1-10wt%. The dried film is treated with aq. soln. having 3.5-10.0pH, washed and dried.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming an inorganic coating film, and more specifically, the present invention relates to a method for forming an inorganic coating film, and more specifically, the present invention relates to a method for forming an inorganic coating film, and more specifically, the present invention relates to a method for forming an inorganic coating film.
The present invention relates to a method for forming an inorganic coating film on the surface of a non-porous substrate such as wood or plastic using a water-soluble alkali metal silicate-based inorganic coating material.

[Conventional technology]

Base materials such as asbestos cement boards and calcium silicate boards are noncombustible and have excellent durability, so they are widely used as building materials and other materials. Generally, these materials themselves have poor cosmetic properties, so when cosmetic properties are required, they are finished with organic paint. However, since this organic coating film is flammable and has poor durability, it significantly impairs the characteristics of the base material. Therefore, nonflammable inorganic paints that can take advantage of the characteristics of these base materials have come into use.

These inorganic paints include those based on water-soluble alkali metal silicate aqueous solutions (so-called water glass), those based on colloidal solutions of silicic acid (so-called colloidal silica),
There are those based on a metal biphosphate aqueous solution and those based on alkyl silicate.

[Problem that the invention seeks to solve]

However, in general, inorganic paints are superior to organic paints in terms of nonflammability, heat resistance, etc., but are inferior in terms of flexibility, gloss, smoothness, etc. In particular, base materials such as asbestos cement boards and calcium silicate boards undergo large dimensional changes due to changes in atmospheric humidity, water absorption, and expansion and contraction due to drying, and inorganic coatings lack the flexibility to sufficiently follow these dimensional changes. Therefore, cracks are likely to occur, and contaminants penetrate and adhere to the cracks, resulting in a decrease in contamination resistance.

Furthermore, due to the occurrence of cracks, the efflorescence component in the base material tends to be eluted onto the surface of the coating film, causing efflorescence.If the coating film contains efflorescence components, the efflorescence phenomenon can be completely suppressed. difficult to do.

Inorganic paints used for decorative purposes such as building materials include heat-curing types and room-temperature curing types. In general, heat-curing paints cannot form a sufficiently cured film unless heated to approximately 200 to 300°C, but when asbestos cement boards or calcium silicate boards are used as the base material, this heating will cause the base material to harden. There are problems such as strength deterioration, degeneration, and discoloration.

Room-temperature curing types rarely deteriorate the substrate, but require a curing period of about 1 week or more to obtain a sufficiently cured film.

Furthermore, in Japanese Patent Publication No. 49-47249, a high viscosity paint made by adding a considerable amount of amorphous silica to an alkali metal silicate and melting it by heating for a long time is applied to the base material, and then treated with a strong acid treatment liquid such as acid. A method for subsequent dry curing is disclosed.

This invention is characterized by the use of a paint in which multi-needle amorphous silica powder is heated and dissolved, and when the silica is not dissolved in sea urchin, which is clearly shown in the comparative example of the same publication, is not effective. This method may have some problems regarding the production of the paint, gloss, etc.

The present invention solves the above problems, and in addition to the non-combustible 11F and heat resistance of conventional inorganic coatings, it also has gloss and smoothness comparable to organic paints and glass glazes. Tsutsumi (J. Particularly, when part +A coated with an inorganic paint film is used in a place where there is a lot of water, such as a kitchen or bathroom, contaminants can penetrate and adhere even to minute racks, contaminating the paint film. However, since there is a problem of deteriorating the aesthetic appearance of decorative parts, the present invention solves this problem and provides a method for forming an inorganic coating film that can be used in kitchens, bathrooms, etc. without losing its aesthetic appearance. Each action has a special purpose.

[Means for solving problems]

The method for forming an inorganic coating film according to the present invention which solves the above problems includes applying an undercoating paint on a base material, which is made of a water-soluble alkali metal silicate or a modified water-soluble alkali metal silicate aqueous solution containing a powder solid content. The resulting coating film is heated at a uniform heating rate of 1 to b, maintained at a specific temperature, and dried until the final moisture content of the coating film is within the range of ~20% by weight (hereinafter referred to as
This is called primary drying. ) and applying on the base coat a water-soluble alkali metal silicate or a modified water-soluble alkali metal silicate aqueous solution that does not contain powder solids or contains substantially less powder than the base coat; The entire coating film obtained is heated for 1 to 15 minutes and maintained at a specific temperature until the final moisture content of the entire coating film is 1.
A step of drying (hereinafter referred to as secondary drying) until the pH value is within the range of ~10% by weight, and a step of drying the coating film obtained in the above step with acid/ammonium having a pH value within the range of 3.5 to 10.0. Treatment with a salt-based aqueous solution (hereinafter referred to as
Also called chemical treatment. ), followed by washing, 1- and drying steps.

In the method of the present invention, since the undercoat layer contains a relatively large amount of powder solids (curing agent, filler, pigment, etc.),
The primary drying produces a relatively porous coating. that time,
By regulating the drying temperature increase rate and final moisture content, the pore size and V of the coating film are controlled to make the coating film as dense as possible. next,
When a water-soluble alkali metal silicate paint that does not contain powder solids or contains small amounts of hardeners, pigments, thickeners, etc. is applied to this undercoat layer l-, a portion of it penetrates into the undercoat layer and coats the undercoat. The layer becomes a denser layer, and a transparent glaze-like glossy thin film containing no or a small amount of powder solids is formed on the surface of the coating layer. This top coat layer is subjected to secondary drying by controlling the temperature increase rate and final moisture content again. The temperature increase rate and final moisture content are defined again to densify the resulting coating film. Then, when immersed in an acid or ammonium salt aqueous solution with a specific pH, the alkali metals in the paint film are selectively and forcibly removed by acid ions, and the paint film hardens, while some of the nucleic acids are removed from the components in the paint film. It also reacts with other substances to produce a hardening effect. After that, by soaking the paint film in water and cleaning it, any remaining unreacted acids in the paint film or base material can be removed.
When substances such as ammonium salts are removed and dried, they contract with the paint film and uniformly form fine racks.

The details will be described later, but according to this method, the combination of undercoat and topcoat gives the paint film cosmetic properties such as gloss, and the hardening of the paint film is done using the chemical treatment described above, so that the hardening is uniform and gradual. This makes it possible to form fine racks that are uniformly dispersed throughout the coating. Moreover,
The coating film is densified by controlling the drying conditions of the undercoat layer and the topcoat layer, and the topcoat paint penetrates into the undercoat layer to further densify the coating film, so in combination with the curing by the chemical treatment described above, The cracks that occur become even finer. In this way, the ultra-fine cracks that are uniformly distributed and pre-formed throughout the coating film absorb the expansion and contraction of the base material, preventing the formation of large cracks, and are so fine that contaminants cannot penetrate. It also guarantees stain resistance in kitchens and bathrooms.

As a result of the coating film being dense and having ultrafine and uniformly dispersed cracks, the coating film is also excellent in efflorescence resistance, cosmetic properties, and the like.

Kyoichi Material There is no essential limitation on the base material to which the inorganic coating film can be applied according to the present invention, and it can be applied to all inorganic and organic molded bodies, regardless of whether they are porous or non-porous. . Typical examples include asbestos cement board, asbestos perlite board, calcium silicate board, asbestos cement calcium silicate board,
Gypsum board, mortar board, concrete board, pulp cement board, wood chip cement board, GRC (glass fiber reinforced cement) board, CFRC (carbon fiber reinforced cement) board, 5FRC (steel fiber reinforced cement) board, ALC board, lock Examples include wool inorganic molded bodies, metal plates, ceramic plates, glass plates, and the like.

Paint The inorganic paint, particularly the undercoat paint, in the present invention is formed by mixing a water-soluble alkali metal silicate-based aqueous solution and powder solids such as a curing agent, filler, and pigment. The amount of powder solids contained in the undercoat ranges from about 10% or more, preferably about 20% or more, based on the weight of the paint, to the amount retained as a paint in the silicate aqueous solution vehicle (for example, about 80% or more). % by weight). Generally about 20-6
Amounts in the range 0% by weight are used. The amount of powder solids in the paint coating ranges from less than about 20% by weight and preferably from less than about 10% to zero.

The water-soluble alkali metal silicate has the general formula M20 ・S
ing・yl+, 0 (where M is an alkali metal belonging to Group 1 of the periodic table, and X and y are positive numbers). A modified water-soluble alkali metal silicate may also be used. Water-soluble alkali metal silicates include sodium silicate, potassium silicate, lithium silicate, etc. The value of X is not particularly limited, but is preferably from 2 to 5 from the viewpoint of film-forming properties and durability. The value of y is not particularly limited either, as long as it is within a range that provides appropriate viscosity to the final composition paint, or within a range that does not cause any trouble in handling the composition. The modified water-soluble alkali metal silicate is produced by adding oxides, hydroxides, fluorides, carbonates, phosphates, etc. of polyvalent metals such as magnesium, aluminum, calcium, zinc, and zirconium to the water-soluble alkali metal silicate. It is made by dissolving and reacting one or more compounds, and contributes to improving the water resistance, chemical resistance, etc. of the coating film. In the inorganic coating material of the present invention, one type or a mixture of two or more of these water-soluble alkali metal silicates or modified water-soluble alkali metal silicates can be used. Practically speaking, sodium silicate is excellent in terms of film-forming properties, adhesion, low cost, etc., and in the present invention, even when one type of sodium silicate is used, an excellent inorganic coating film can be obtained. The amount of the alkali metal silicate added is based on the weight of the paint,
about 7% or more, preferably about 10% or more, more preferably about 15% or more, and typically about 10% or more
% range.

Hardening agents for the water-soluble alkali metal silicate or modified water-soluble alkali metal silicate include polyvalent metal oxides such as zinc oxide, magnesium oxide, and aluminum oxide; magnesium hydroxide, aluminum hydroxide, etc. polyvalent metal hydroxides; polyvalent metal carbonates such as zinc carbonate and magnesium carbonate;
These include polyvalent metal phosphates such as magnesium phosphate, aluminum phosphate, and zinc phosphate; silicofluorides such as zinc silicofluoride and aluminum silicofluoride; and organic compounds such as glyoxal and oxalic acid amide. One or more types of curing agents are used. An effective amount of curing agent is about 1% or more, preferably about 3% or more, typically about 5% by weight of the coating.
% or more.

Fillers include granular materials such as silica stone, alumina, and glass powder;
These include flat materials such as clay and mica; fibrous materials such as asbestos and glass fiber powder.

Pigments include titanium dioxide, hengara, yellow lead, chrome clean, ultramarine blue, mars violet, cobalt blue, and carbon blank.

Other additives include known surfactants, dispersants,
Antifoaming agents, thickeners, etc. are included and are added as necessary.

In addition, it is better to add a curing agent to the undercoat paint [1r] in order to improve the adhesion with the substrate and the curing properties of the one-coat film, and also to improve the strength, durability, etc. of the paint film. Solid substances such as fillers are added to make the grains stick or to uniformly generate fine racks. In this way, the undercoat film layer has the function of a paint film, and also has the role of supplementing the hardening of the topcoat film by allowing the topcoat to penetrate appropriately and reacting with the unreacted curing agent in the undercoat paint layer. I will fulfill it.

In addition, a surfactant, an antifoaming agent, a thickener, etc. may be added as necessary.

Undercoating In the method of the present invention, first, an undercoating paint as described above is applied to the surface of the substrate. This application can be done by spraying, dipping, roll coater, curtain coater, etc.

The undercoat film is a main part of the inorganic paint film according to the present invention, and its thickness may be within a range that satisfies the various performances required as a paint film. The thickness of the undercoat layer after curing is usually in the range of 20 to 100 μm. If it is less than 20 μm, the surface strength will be weak and the cosmetic properties will also be poor. When it is 100 μm or more, large ranks tend to occur during the primary or secondary drying of the coating film or during acid/ammonium solution treatment, impairing performance such as water permeability and stain resistance.

Further, regarding the particle size of the powder solid content, in order to obtain a smooth coating surface, it is sufficient that the maximum particle size of the powder solid content is smaller than the film thickness. However, if powder solids with a large particle size are added to form a coating film with a special surface texture (e.g. powder solids protrude from the coating surface to create a pattern), this range will not apply. do not have.

Further, the average particle size of the powder solid content is preferably 1 μm or more. When the average particle size is less than 1 μm, the filling property of the powder solid content in the coating layer becomes poor, which causes a large rank.

Primary Drying During the primary drying after applying the undercoat paint, the average rate of increase in the surface temperature of the paint film is within the range of 1°C/min to 10°C/min, and the water content in the paint film is increased. rate is 1wt%~20-t
The surface temperature is maintained for a certain period of time until the temperature reaches %. By performing the primary drying under such conditions, the water in the coating film evaporates slowly, and the balance between this evaporation rate and the condensation of the silanol groups of the water-soluble alkali metal silicate is improved. It is possible to minimize the incorporation of bores due to evaporation of water in the coating film, and it is possible to form a dense undercoat layer.

If the average rate of increase in the surface temperature of the coating film exceeds 10°C/min, the rate of evaporation of water in the coating film becomes too fast and the balance with the condensation of silanol groups is disrupted, causing the bore to become ineffective. This may result in a porous coating layer with a desired amount of incorporation, or may cause foaming.

On the other hand, if the drying time is less than 1° C./min, the drying time becomes too long and the drying conditions are not good in terms of workability and economy.

In the primary drying, the final moisture content in the coating film is 1wt%~
Keep it within the range of 20-1%. In order to bring the final moisture content within this range, it is usually sufficient to maintain the surface temperature of the coating film at 40° C. to 150° C. for about 1 minute to 48 hours.

When this water content exceeds 20 wt%, there is still a large amount of water remaining in the paint film, so the formation of pores in the undercoat film becomes insufficient, resulting in sufficient penetration of the second coat paint. If this is not done properly, the effect of densifying the coating film by applying the top coat will be poor. In addition, when the moisture content becomes 1wt%,
As the condensation of silanol groups progresses too much, alkali metal components (e.g. Na, K) are firmly incorporated into the condensate, so the alkali metal components can be efficiently eluted in the next chemical treatment with an aqueous acid/ammonium salt solution. It cannot be removed. If the alkali metal component cannot be eluted and removed from the coating film by chemical treatment, high-temperature heating (for example, 230° C. or higher) is required to cure the coating film, which causes heating deterioration of the base material.

The top coat imparts gloss, smoothness, stain resistance, aesthetics, etc. to the paint film, and fills in the pores formed in the undercoat film, forming a dense layer through primary drying.16) This is done to make the undercoat film more dense. A water-soluble alkali metal salt aqueous solution or a modified water-soluble alkali metal salt aqueous solution is used as the top coat, but no hardening agent or filler powder solids are added, or the above characteristics are used to prevent foaming during heating, coloring, etc. Add a small amount of curing agent, pigment, etc. to the extent that it does not reduce the Generally, the minimum necessary amount of curing agent may be added, and it is also desirable to use a water-soluble curing agent (glyoxac) in combination.

The thickness of the overcoat layer is not particularly limited, but a range of up to 10 μm after curing is usually suitable.

Since the top coat layer has a small to no powder solid content,
If it exceeds μm, a large rank will occur, impairing the stain resistance or causing foaming.

Top coat paint can be applied by spraying, dipping, roll coater,
This can be done with a curtain coater.

In primary I secondary drying, after applying the top coat, the average rate of increase in the surface temperature of the paint film is kept within the range of 1°C/min to 10°C/7 min to warm the stomach, and further reduce the water content in the paint film. Rate is 1ivt% ~
The surface temperature is maintained for a certain period of time until it falls within the range of 10-t%. This makes it possible to form a dense one-coat layer for the same reason as the primary drying. In addition, as mentioned above, a part of the top coat has penetrated into the undercoat layer and has the function of making the undercoat layer even more dense.

In this secondary drying, the average temperature increase in the surface temperature of the coating film is set to 1 to b.The reason is the same as in the case of the primary drying.

In the secondary drying, the moisture content in the coating film is finally 1 int% to 1Qw based on the entire coating film of the undercoat layer and topcoat layer.
within the range of t%. To keep the moisture content within this range,
Usually, the surface temperature of the coating film is kept at 40℃~150℃ for 10 minutes~4
It is sufficient to hold it for about 8 hours. If the water content exceeds 10 wt%, the condensation of silanol groups will be insufficient, and even condensates of silanol groups will be decomposed in the chemical treatment in the subsequent step, making it impossible to selectively and efficiently elute and remove alkali metal components. Furthermore, if the water content reaches 1 ivt%, the condensation of the silanol groups will proceed too much and the alkali metal components will be firmly incorporated into the condensate, making it impossible to elute and remove the alkali metal components efficiently in chemical treatment. . As mentioned above, if the alkali metal components cannot be selectively and efficiently eluted and removed by chemical treatment, high-temperature heating will be required to cure the coating film.

After the secondary drying of the chemical treatment, the coating film is immersed in an aqueous acid/ammonium salt solution to selectively elute and remove the alkali metal component, thereby curing the coating film.

When a paint film is formed by chemically curing with a weakly acidic to neutral acid/ammonium salt aqueous solution, the hardening of the paint film is more uniform and gradual compared to the heat curing method, so fine particles are evenly dispersed in the paint film. occurs.

Generally, if a water-soluble alkali metal silicate aqueous solution is simply applied and a dried coating film is heated to a high temperature or simply left to stand, large cranks with a width of about 10 to 20 μm will occur. However, we have found that by applying a water-soluble alkali metal silicate aqueous solution and, after drying, treating it with an acid/ammonium salt aqueous solution with a pH of 3.5 to 10, a large number of fine racks with a width of about 1 to 2 μm are formed on the entire surface of the coating film. It has been found that it can be formed in a uniformly dispersed manner. The cranks generated in this way are so fine that they cannot enter the dyeing material, and even if dimensional changes or deflections occur due to water absorption expansion or drying shrinkage of the base material, the stress is dispersed and absorbed by the rack to ensure uniformity. , large racks that cause a decrease in stain resistance no longer occur, and stain resistance and efflorescence resistance are good. Moreover, the method of the present invention further densifies the dried coating film by controlling the temperature increase rate and final moisture content of the primary drying and secondary drying, and also densifies the coating film after the drying by applying a topcoat. As a result of further densification of the undercoat layer by penetrating it into the undercoat layer after drying, the width of cracks that occur and are evenly distributed in the cured coating obtained after treatment with this acid/ammonium salt-based aqueous solution is more general. It can be made as fine as approximately 0.4 to 0.8 μm.

Even a coating film having uniformly dispersed cracks with a width of 1 to 2 μm has sufficient lη staining resistance as long as it is used for general purposes such as walls and ceilings. However, when used in areas with close water areas such as kitchens and bathrooms that are easily contaminated, widths of 1~
Even in a coating film as fine as 2 μm, contaminants are deposited, contaminating the coating film and deteriorating its aesthetic appearance. but,
By the method of the present invention, the crack width is 0.4 to 0.8 μm.
When the particles are refined to such a degree, the coating film will not be contaminated and its aesthetic appearance will not be impaired even if it is used in places with severe water access, such as in -1-.

In addition, alkali metals in the coating film that become efflorescence components are removed by treatment with an acid/ammonium salt aqueous solution.
A coating film with excellent efflorescence resistance can be obtained. Furthermore, when using a cement material such as an asbestos-cement board or a calcium silicate board as the base material of the present invention, high-temperature heating is not required, and after drying at a relatively low temperature, acid and
Since it is cured using an aqueous ammonium salt solution, it does not cause deterioration of the base material. Furthermore, since the free Ca component which becomes the efflorescence component in the base material can be fixed with acid, the efflorescence resistance can be improved.

Furthermore, base materials containing asbestos or glass fiber as reinforcing materials will not be deteriorated.

An acid/ammonium salt aqueous solution refers to an aqueous solution of a salt that is a reaction product or a reaction product mixture of an acid or an acidic salt and ammonia, aqueous ammonia, or an ammonia compound, and typically includes (1) adding a nucleic acid to water; - Can be prepared by dissolving an ammonium salt, or (2) adding an acid and ammonia water or ammonia gas to water, etc.

As the acid component of the salt of the acid/ammonium salt aqueous solution, inorganic acids and organic acids or their acid salts can be used. Examples of inorganic acids include phosphoric acid, hydrochloric acid, sulfurous acid, sulfuric acid, nitric acid, aluminum chloride, aluminum sulfate, and Typical examples include aluminum monophosphate, monocalcium phosphate, aluminum nitrate, and organic acids include oxalic acid, citric acid, acetic acid, tartaric acid, etc., but are not limited to these. Note that typical acid/ammonium salts include ammonium phosphate, ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium acetate, etc., but in general, primary, secondary, and/or tertiary ammonium phosphates are particularly preferred. suitable.

The pH value of acid/ammonium salt aqueous solutions is generally 3.5.
-10.0, preferably 4-9, and more preferably 4.5-8.5 and particularly preferably 5-8. Outside the range of 3.5 to 10.0, the effects of the present invention are generally difficult to achieve.

In order to adjust the aqueous solution to a desired pH value, for example, ammonia water or ammonia gas, or a nucleic acid may be appropriately added to the aqueous solution. If necessary, it is also possible to add appropriate buffering agents to effectively maintain the desired pH value. Note that the salt component of the acid/ammonium salt aqueous solution may be a mixture of two or more types of salts.

If the pH value of the acid/ammonium aqueous solution is below 3.5, the elution rate of the alkali metal components in the coating film may become rapid.
The elution of coating film components other than alkali metal components also becomes more intense.
occurrence of large cracks, strength, durability, gloss, smoothness,
It causes deterioration in aesthetic appearance.

In addition, cement-based base materials and materials with asbestos added as reinforcing materials are more likely to be eroded.

When the pH value is 10.0 or more, components other than the alkali metal components are eluted in large quantities, and the gloss, smoothness, and aesthetics of the coating film are reduced. Usually, as a chemical treatment condition, the concentration of the acid/ammonium salt aqueous solution is adjusted to the above-mentioned pl+ range, and is typically about 0.2 to about 20% by weight, and typically about 0.2% by weight.
5 to about 10% by weight, processing liquid temperature from room temperature to about 60°C,
The treatment time is preferably about 1 to 24 hours. in short,
Regarding the chemical treatment conditions, it is necessary to use a chemical solution that can selectively remove the alkali metal components in the coating film at an appropriate elution rate and has a pH value that does not easily attack the base material components.

After the chemical treatment with the acid/ammonium salt aqueous solution, the coating film is immersed in water to remove unreacted water-soluble substances such as the acid/ammonium salt in the coating film and the base material. Usually, immersion in water can be carried out for about 1 to 24 hours. Note that the immersion and removal time can be shortened by immersing in saline solution or the like instead of immersing in water.

A strong base that works to shorten the cleaning time is a strong base that acts on the remaining ammonium salt and promotes its removal (for example, decomposition by chemical reaction) and has virtually no effect on the coating film. Strong acids/salts (e.g. NaCl or KCI)
(for example, about 0.1 to 5% by weight). After washing and drying, the process is completed.

〔Example〕

” can example ↓ (1) Preparation of paint For the undercoat paint, mix the ingredients shown below except for the sodium silicate aqueous solution, surfactant, and antifoaming agent in a bot mill.
After mixing for 6 hours, the remaining mixture was added and the mixture was stirred with a screw for 15 minutes.

Preparation of undercoat paint (silicate) IJium aqueous solution (40% liquid) 100 parts by weight Zinc oxide 30 parts by weight Silica powder 40 parts by weight Sodium pyrophosphate 2 parts by weight Titanium white
20 Jubin water
90 parts by weight surfactant (5% liquid)
1 Heavy wall antifoaming agent (5% liquid)
1 part by weight The top coat paint was prepared by mixing and stirring using the formulation shown below.

Preparation of Top Coat Paint Sodium silicate water 1i'& (40% liquid) 100 parts by weight Water 100 parts by weight Surfactant (5% liquid) 1 parts by weight Defoaming agent (
5% liquid) 1 part by weight (2) Paint Undercoat paint was applied to a calcium silicate board (thickness 3■■) to a thickness of approximately 180 μm by air spray, and the average rate of increase in the surface temperature of the paint film was adjusted to 4℃/ The surface temperature was maintained at 80° C. for 10 minutes to perform primary drying (final moisture content: 12%). Next, the top coat is applied to the primed painted board to a thickness of approximately 40 μm by air spray, the average rate of increase in the surface temperature of the coating film is increased at 3°C/min, and the surface temperature is maintained at 130°C for 2 hours. Secondary drying was performed (final moisture content: 6%). This was immersed in an aqueous ammonium phosphate solution (2.5% monoammonium phosphate and 21 J ammonium phosphate, 2.5%, pl + 6.5) at 30°C, and then immersed in water for 12 hours. After being immersed for a period of time, it was washed with water and dried at 80°C. The thickness of the cured coating is approximately 40 μm for the undercoat layer, -
1-The coating layer was approximately 3 μm.

Example ↑ (1) Preparation of paint The preparation of Example 1 was changed as shown below and prepared in the same manner.

Preparation of undercoat paint Sodium silicate aqueous solution (40% liquid) 60 parts by weight Potassium silicate aqueous solution (30% liquid) 40 parts by weight Aluminum polyphosphate 10 parts by weight Magnesium oxide 15 parts by weight Silica stone powder
45 parts by weight Potassium pyrophosphate 1, 2 parts by weight Aerosil
0.5 parts by weight cobalt blue
10 parts by weight water
70 parts by weight surfactant (5% liquid)
1 part by weight antifoaming agent (5% liquid)
1. The heavy-duty area topcoat paint was prepared by mixing and stirring using the formulation shown below.

Preparation of top coating paint Sodium silicate aqueous solution (40% liquid) 100 parts by weight Cobalt blue 10 parts by weight Potassium pyrophosphate 2 parts by weight Water
100 parts by weight Surfactant (5% liquid) 1 part by weight Antifoaming agent (
5% liquid) 1 part by weight (2) Paint Undercoat paint was applied to an asbestos slate board (thickness 31cm) to a thickness of about 200 pm by air spray, and the average rate of increase in the surface temperature of the coating film was 5°C. Primary drying was carried out by increasing the temperature at a rate of 1/min and maintaining the surface temperature at 60° C. for 30 minutes (final moisture content 10%). Next, apply two coats of paint to the base coated board to a thickness of approximately 60 μm using air spray, and raise the average surface temperature of the paint film at a rate of 2°C/min to bring the surface temperature to 120 μm. Secondary drying was performed by holding at ℃ for 5 hours (final moisture content 5%). This was mixed with an ammonium phosphate aqueous solution (5% phosphoric acid solution by blowing ammonia gas into it at 40°C).
The H value was adjusted to 7.0. ) for 6 hours, and further immersed in 0.5% saline for 5 hours, washed with water, and dried in the air. The thickness of the cured coating is approximately 45 μm for the undercoat layer.
-L coating layer was about 5 μm.

Fanning Example 1 (11 Preparation of Paint) The preparation of Example 1 was changed as shown below, and the preparation was carried out in the same manner.

Preparation of undercoating paint Sodium silicate J, aqueous solution (40% liquid) 65 parts by weight Potassium silicate aqueous solution (30% liquid) 20 parts by weight Lithium silicate aqueous solution (25% liquid) 15 parts by weight Magnesium polyphosphate 15 parts by weight Zinc polyphosphate
10 parts by weight alumina powder
40 parts by weight synthetic mica
10 Part by weight titanium itself
15 parts by weight water
90 parts by weight Surfactant (5% liquid) 1
Parts by weight Antifoaming agent (5% liquid) 1 part by weight The paint was prepared by mixing and stirring using the formulation shown below.

Preparation of top coating paint Sodium silicate aqueous solution (40% liquid) 50 parts by weight Potassium silicate aqueous solution (30% liquid) 50 parts by weight Water
100 parts by weight Surfactant (5% liquid) 1 part by weight (2) Apply the undercoat paint to an asbestos cement calcium silicate board (thickness 4 mm) to a thickness of about 150 μm by air spray,
The average rate of increase in the surface temperature of the coating film was increased at a rate of 4° C./min, and the surface temperature was maintained at 90° C. for 10 minutes to perform primary drying (final moisture content 9%).

Next, the top coat paint was applied to the primed painted board to a thickness of approximately 50 μm by air spray, and the average rate of increase in the surface temperature of the paint film was increased at 2°C/min.
Secondary drying was performed by holding for 0 minutes (final moisture content q%).

This was immersed for 8 hours in an aqueous ammonium phosphate solution at 30° C. (the pH value was adjusted to 8.0 by adding concentrated aqueous ammonia to a 5% phosphoric acid solution), washed with water, and dried in the air.

The thickness of the cured coating film was approximately 36 μm for the negative coating layer and approximately 3.5 μm for the undercoat layer.

Comparative Example 1 - +l) Preparation of paint Same as Example 1 (2) Painting The procedure of Example 1 except that the average rate of increase in the surface temperature of the paint film was increased at 15°C/min in the primary drying. , The same coating as in Example 1 was performed. (Final moisture content is also the same as Example 1) Comparative example -? 0) Preparation of paint Same as Example 1 (2) Painting Same as Example 1 except that the average rate of increase in the surface temperature of the coating film was increased at 15°C/min in the secondary drying. Painted in the same way. (The final moisture content is also the same as in Example 1) Comparative Example - (Preparation of 11 Paints Same as Example 2 (2) The holding time after raising the surface temperature of the coating film at 60°C for 5 minutes during the paint drying process Coating was carried out in the same manner as in Example 2, except that the average rate of increase in temperature during the primary drying was 5°C/min, but the holding time was shortened from 30 minutes to 5 minutes. The final moisture content after subsequent drying was 25%.

Example 14 - +11 Preparation of paint Same as Example 2 (2) Example except that the holding time after raising the surface temperature of the paint film was changed to holding at 120°C for 30 minutes due to the hot weather during the secondary drying of the paint. Painting was done in the same way as 2. In this case, the final moisture content after secondary drying was 13 wt%.

Evaluation of Examples and Comparative Examples The performance of the coating films obtained by each side was tested using the following test methods and evaluation criteria.

(1) Maximum crack width After being left in the air for three months, measurements were made using an electron microscope.

(2) Water permeability In accordance with JIS A6910 (Water permeability test method for multi-layer patterned sprayed materials), hold the test piece horizontally, place a piece of glue with a diameter of approximately 75 cm upside down on the test piece, and apply silicone sealant. After fixing the test piece with water and leaving it for 48 hours, water was poured into the test piece to a depth of about 250 mm from the surface of the test piece, and the height of the water head after leaving it for 24 hours was measured, and the amount of water permeation was determined from the difference from the height before the test.

(3) Stain resistance According to JIS A3703 (stain resistance test method for interior plastic decorative boards), the test piece was held horizontally and a commercially available blue black ink was applied to the coating surface using a pipette. Q. 5 mI each was dropped onto about 3 or more locations, and after the drops were allowed to stand for 24 hours, the ink was wiped off using soapy water. Those with no change in gloss or color were rated O1, those with a slight change were rated Δ, and those with significant change were rated x. O can be used for special purposes such as kitchens and bathrooms, and Δ can be used for normal purposes such as walls and ceilings.

(4) Irradiate for 500 hours with an accelerated weathering sunshine weather meter.
The surface condition of the coating film was visually observed.

○ indicates no change, Δ indicates slight decrease in gloss or slight discoloration, and indicates marked decrease in gloss or discoloration, or large rack.
Those in which blistering and peeling were observed were rated x.

(5) Boiling water resistance The coating film was immersed in boiling water at 100° C. for 8 hours, and the surface condition of the coating film was visually observed, and the coating surface was scratched with a knife to check for softening. Those with no change are rated as O, those with slight decrease in gloss or slight discoloration as Δ, and those with significant decrease in gloss or discoloration, or those with large racks, blisters, peeling, and softening as ×. did.

(6) Efflorescence resistance One cycle consists of leaving the back side of the sample in a humid environment for one day and then air-drying it for one day. Perform 10 cycles and visually observe the surface appearance of the coating film. Those in which efflorescence did not occur were marked as ○, and those in which efflorescence occurred were marked as ×.

(7) Gloss Visually inspected. Good gloss was rated ○, slightly poor gloss was Δ, and poor gloss was rated ×.

(8) Acid-resistant 10% HCI aqueous solution is applied for 15 minutes, after which the surface is washed with water, dried, and then visually observed. ○ those with no change, those with slightly reduced luster,
Or, those with slight discoloration were rated as Δ, and those with significant decrease in gloss or discoloration, or those with large racks, blisters, or peeling were rated as ×.

(9) Alkali resistance A 10% NaOH aqueous solution was applied for 15 minutes, washed with water, and after drying, evaluation was made using the same criteria as for acid resistance.

OI Adhesive 100 squares of 2 w x 2*■ were made on the surface of the coating film using a knife, adhesive tape was applied to the entire surface, and the squares were instantly peeled off. A case in which not even one ff111 square of the coating film was peeled off was marked as ○, and a case in which even one square was peeled off was marked as ×.

Below margin The results are summarized in the table below.

Table [Effects of the Invention] As is clear from the above description and examples, the present invention provides an inorganic coating film with excellent nonflammability and heat resistance that has gloss and smoothness comparable to organic paints and glass glaze surfaces. Provided is a method for forming an inorganic coating film that has excellent flexibility, stain resistance, and efflorescence resistance, and does not cause heat deterioration of the base material, and is particularly suitable for use in easily contaminated areas such as kitchens and bathrooms. An inorganic coating film that does not lose stain resistance is provided.

Claims (1)

[Claims] 1. Applying an undercoating paint consisting of a water-soluble alkali metal silicate or a modified water-soluble alkali metal silicate aqueous solution containing a powder solid content onto a substrate, and applying the resulting coating film to the base material, A step of increasing the temperature of the coating film surface at an average temperature increase rate within the range of 1 to 10°C/min, maintaining it at a specific temperature, and drying the coating film until the final moisture content is within the range of 1 to 20% by weight. , Applying a water-soluble alkali metal silicate or a modified water-soluble alkali metal silicate aqueous solution containing no powder solid content or substantially less than the above-mentioned undercoat paint onto the undercoat film, and obtaining the resulting coating. The entire film is heated at an average heating rate of 1 to 10°C/min on the surface of the coating, and maintained at a specific temperature until the final moisture content of the entire coating is within the range of 1 to 10% by weight. and a step of treating the coating film obtained in the above step with an acid/ammonium salt aqueous solution having a pH value within the range of 3.5 to 10.0, washing and drying it. A method for forming an inorganic coating film.