JPS6239027B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a mineral base material (collectively referred to as a mineral base material) consisting of a porous inorganic base material or a non-porous mineral base material such as metal or glass. The present invention relates to a method of forming an inorganic coating film for finishing a paint with a decorative coating. Base materials such as asbestos cement boards and calcium silicate boards are noncombustible and have excellent durability, so they are widely used for building materials and other purposes. 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. However, in general, inorganic paints are superior in nonflammability and heat resistance compared to organic paints, but they are less flexible and
It is inferior in terms of gloss, smoothness, etc. In particular, base materials such as asbestos cement boards and calcium silicate boards undergo large dimensional changes due to atmospheric humidity changes, 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 paint film, causing efflorescence. difficult to suppress. 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 causes the base material to harden. strength deterioration, degeneration,
There is a problem with discoloration. Room-temperature curing types rarely deteriorate the substrate, but require a curing period of about one week or more to obtain a sufficiently cured film. As a method for solving the above problems, the present inventors first coated a paint containing a water-soluble alkali metal silicate, etc., treated it with an acid solution to remove the acid, and then He invented a method that includes the step of curing the coating film after overcoating it (patent application filed in 1983).
−211612). On the other hand, the present invention can be said to be an improvement over this prior invention from one point of view. In addition, in Japanese Patent Publication No. 49-47249, a highly viscous 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 coating material in which a large amount of amorphous silica powder is heated and dissolved, and as clearly shown in the comparative examples of the same publication, it is not effective when the silica is not dissolved. Not demonstrated. This method includes the production of the paint,
There may be some problems with gloss etc. The main objective of the present invention is to provide a new method that improves the above problems. In other words, the present invention not only has the nonflammability and heat resistance of conventional inorganic coatings, but also has the gloss and smoothness of organic paints and glass glazes, and has the flexibility and resistance that have been the drawbacks of inorganic coatings. The present invention provides a method for forming an inorganic coating film that provides a coating film with excellent stain resistance and efflorescence resistance, and does not cause heat deterioration of the base material. To summarize a typical embodiment of the present invention, a water-soluble alkali metal silicate-based aqueous solution paint (hereinafter referred to as an undercoat paint) containing powder solids selected from fillers, pigments, hardeners, etc., is applied onto a mineral base material. ) and dry it appropriately, then apply the silicate-based aqueous solution paint (hereinafter referred to as topcoat paint) whose powder solid content is smaller to zero than the undercoat paint and dry it moderately. The applied coating film has a pH value of about 3.5 to approx.
This is a method for forming an inorganic coating film, which is characterized by applying a 10.0 acid/ammonium salt aqueous solution, washing with water, and drying. Preferably, at least the base coat of the paint contains an effective amount of a curing agent. If necessary, a coating film formed by applying the silicate-based aqueous paint having a solid content between the above two coatings between the two coatings may be treated in the same manner to form the inorganic coating film of the present invention. Of course, it is also possible to form . In the above method, in place of water during washing with water, a strong base-strong acid which acts on the remaining ammonium salt etc. to promote removal (for example, decomposition by chemical reaction) and has virtually no effect on the coating film. A dilute aqueous solution of a salt (e.g. NaCl or KCl) (e.g. 0.1~
(approximately 5% by weight), the washing time is shortened. The PH value of the acid/ammonium salt aqueous solution mentioned above is
It generally ranges from about 3.5 to about 10.0, preferably from about 4 to about 9, and more preferably from about 4.5 to about 8.5 and typically from about 5 to about 8. Outside the range of about 3.5 to 10.0, the effects of the present invention are generally difficult to achieve. The acid/ammonium salt aqueous solution refers to an aqueous solution of a salt that is a reaction product or reaction product mixture of an acid or an acidic salt and ammonia, aqueous ammonia, or an ammonia compound, and typically includes (1) It can be prepared by dissolving the acid/ammonium salt or (2) adding an acid and ammonia water or ammonia gas to water. In order to adjust the aqueous solution to a desired pH value, for example, ammonia water, ammonia gas, or the acid may be appropriately added to the aqueous solution. If necessary, it is also possible to add a suitable buffer 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. As the acid component of the salt of the acid/ammonium salt aqueous solution, inorganic acids and organic acids or acid salts thereof can be used. Examples of inorganic acids include phosphoric acid, hydrochloric acid, sulfurous acid, sulfuric acid, nitric acid, aluminum chloride, aluminum sulfate, Typical examples include monobasic aluminum phosphate, monobasic calcium phosphate, aluminum nitrate, etc., and examples of organic acids include oxalic acid, citric acid, acetic acid, tartaric acid, etc., but are not limited to these.
Note that representative 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. .
Examples of the base material in the present invention include asbestos cement board,
Asbestos perlite board, calcium silicate board, asbestos cement calcium silicate board, gypsum board, mortar board, concrete board, pulp cement board,
Includes wood chip cement boards, GRC (glass fiber reinforced cement) boards, CFRC (carbon fiber reinforced cement) boards, SFRC (steel fiber reinforced cement) boards, ALC boards, rock wool inorganic moldings, metal plates, glass plates, etc. The inorganic paint in the present invention is formed by mixing a water-soluble alkali metal silicate-based aqueous solution and powder solids such as a hardening agent, filler, and pigment. The amount of powder solids contained in the base coat in the above embodiments is from about 10% or more, and preferably from about 20% or more, based on the weight of the paint, retained as a paint in the aqueous silicate vehicle. (e.g., about 80% by weight). Amounts ranging from about 20 to about 60% by weight are generally used. The amount of powder solids in the topcoat in the embodiments described above ranges from less than about 20% by weight and preferably from less than about 10% to zero. Water-soluble alkali metal silicates have the general formula M ₂ O.
xSiO ₂ ·yH ₂ O (However, M is an alkali metal belonging to Group 1 of the periodic table, and x and y are positive numbers.)
However, a modified water-soluble alkali metal silicate obtained by modifying this water-soluble alkali metal silicate with a polyvalent metal compound 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, durability, etc. 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 about 7% or more, preferably about 10% or more, more preferably about 15% or more, and typically about 15% or more, based on the weight of the paint.
The range is approximately 60%. The curing agent for the above-mentioned water-soluble alkali metal silicate or modified water-soluble alkali metal silicate includes polyvalent metal oxides such as zinc oxide, magnesium oxide, and aluminum oxide; polyvalent metals such as magnesium hydroxide and aluminum hydroxide. Hydroxide; Polyvalent metal carbonates such as zinc carbonate and magnesium carbonate; Polyvalent metal phosphates such as magnesium phosphate, aluminum phosphate, and zinc phosphate; Silica fluoride such as zinc silicofluoride and aluminum silicofluoride compounds; organic compounds such as glyoxal and oxalamide; one of these curing agents
Use one type or two or more types. The effective amount of curing agent is about 1% or more, preferably about 3% by weight of the coating.
% or more, typically about 5% or more. Examples of fillers include granular materials such as silica stone, alumina, and glass powder; flat materials such as clay and mica; and fibrous materials such as asbestos and glass fiber powder. Pigments include titanium dioxide, red iron, yellow lead, chrome green, ultramarine blue, mars violet, cobalt blue, and carbon black. Other additives include known surfactants,
There are dispersants, antifoaming agents, thickeners, etc., which are added as necessary. Next, a method for forming an inorganic coating film according to the present invention will be explained. In the present invention, the first layer is obtained by applying a water-soluble alkali metal silicate paint containing a hardening agent, filler, pigment, etc., and after primary drying, the powder solid content of the hardening agent, filler, pigment, etc. A second layer is obtained by applying a water-soluble alkali metal silicate paint that does not contain or contains small amounts of hardeners, fillers, pigments, thickeners, etc., and after secondary drying, An inorganic coating film can be formed by immersing it in an acid/ammonium aqueous solution, then immersing it in water, and finally drying it. In the above embodiment, since the first layer contains a relatively large amount of solid powder such as a curing agent, filler, and pigment, a relatively porous coating film can be formed by primary drying. When this first layer is coated with a water-soluble alkali metal silicate paint that does not contain powder solids or contains small amounts of hardeners, pigments, thickeners, etc.
A part of it penetrates into the first layer, making the first layer a dense layer, and a part of it forms a transparent glaze-like thin film on the upper surface of the first layer that does not contain powder solids or contains a small amount of powder solids as a second layer. do. After that, secondary drying is performed at a temperature that does not cause foaming of the second layer, and the alkali metals in the coating film are selectively and forcibly removed by acid ions by immersion in an acid/ammonium salt aqueous solution with the above-mentioned PH value. In addition to curing the coating film by removing it, it is thought that a portion of the acid also reacts with components in the coating film to bring about a curing effect. After that, by immersing the paint film in water, residual unreacted acids, ammonium salts, and other substances in the paint film and base material are removed, and when this is dried, the paint film shrinks and fine cracks are uniformly removed. Occur. The characteristics of the present invention can be summarized as follows: (1) The surface of the coating film has a transparent glaze-like appearance, and has a good appearance and texture. (2) If a coating film is manufactured by chemically curing with a weakly acidic to neutral acid/ammonium salt aqueous solution, the coating film will harden more uniformly and slowly compared to the heat curing method, so fine particles will be uniformly formed on the coating film. A crack occurs. The cracks generated in this way are so fine that contaminants cannot penetrate, and even if the base material undergoes dimensional changes or deflections due to water absorption expansion, drying shrinkage, etc., the uniform cracks will disperse and absorb stress. Large cracks that cause a decrease in stain resistance no longer occur, and stain resistance is good. (3) Treatment with an acid/ammonium salt aqueous solution removes alkali metals in the coating film that become efflorescence components, resulting in a coating film with excellent efflorescence resistance. 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, the above-mentioned PH
Because it is cured with aqueous acid/ammonium salt solution, it does not cause deterioration of the base material. Furthermore, since the free Ca component that 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. It is better to add a curing agent to the undercoat paint forming the first layer in order to improve the adhesion with the base material and the curing properties of the topcoat film, and also to improve the strength of the paint film.
It is better to add solid substances such as fillers to provide functions such as durability and to uniformly generate fine cracks. In this way, the undercoat film layer is
In addition to having the function of a coating film, it also plays the role of allowing the top coat to penetrate appropriately and reacting with the unreacted curing agent in the undercoat layer to supplement the hardening of the top coat. In addition, a surfactant, an antifoaming agent, a thickener, etc. may be added as necessary. Water-soluble alkali metal silicate is also used for the top coat that forms the second layer, but in order to give the dense film stain resistance, gloss, smoothness, aesthetics, etc., hardeners, fillers, etc. Do not add solids or
Alternatively, a hardening agent, a pigment, etc. may be added in small amounts to prevent foaming during heating, coloring, etc. so as not to cause a decrease in the above-mentioned performance. In addition, in the above embodiment where only the top coating is used, it is preferable to add the minimum necessary amount of curing agent. It is also desirable to use a water-soluble curing agent (glyoxal) in combination. The primary drying of the undercoat after application is sufficient as long as the undercoat dries uniformly, and may be maintained at room temperature to about 100° C. for about 1 minute to 60 minutes. The secondary drying of the top coat after application differs depending on the type of curing agent, but it does not completely cure the paint film and allows the alkali metal components to be selectively and efficiently eluted and removed in the next chemical treatment process, and the top coat does not completely cure. The conditions are such that the layer does not foam. Typically room temperature to approx.
It may be kept at 150°C for about 30 minutes to 48 hours. If the PH value of the acid/ammonium aqueous solution is about 3.5 or less, the elution rate of the alkali metal components in the coating film becomes rapid, and the elution of coating film components other than the alkali metal components becomes intense, leading to the occurrence of large cracks, strength loss, etc. It causes a decrease in durability, gloss, smoothness, and aesthetics. In addition, cement-based base materials and materials to which asbestos or the like is added as a reinforcing material are more likely to be eroded. When the PH value is about 10.0 or more, components other than alkali metal components will elute more and the gloss of the coating film will decrease.
Smoothness and aesthetics deteriorate. Normally, as a chemical treatment condition, the concentration of acid/ammonium salt aqueous solution is the above-mentioned PH.
from about 0.2 to about 20% by weight and typically from about 0.5 to about 10% by weight, subject to adjustment to a range.
Processing liquid temperature is room temperature to approximately 60℃, processing time is approximately 1 to 24
About an hour is desirable. 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. Generally, immersion in water can be carried out for about 1 to 24 hours. Note that, if the material is immersed in saline solution or the like instead of immersed in water, the immersion and removal time can be reduced to about half. Hereinafter, typical examples of the present invention will be explained in detail using Examples and Comparative Examples. Example 1 (Example) (1) Preparation of paint For the undercoat paint, ingredients other than the sodium silicate aqueous solution, surfactant, and antifoaming agent were mixed in a pot mill for 24 hours from the formulation shown below, and the remaining ingredients were added to the mixture for 15 hours.
It was prepared by stirring the screw for a minute. Preparation of undercoat paint Sodium silicate aqueous solution (40% liquid)
100 [parts by weight] Zinc oxide 30 〃 Silica stone powder 40 〃 Sodium tripolyphosphate 2 〃 Titanium white 20 〃 Water 90 〃 Surfactant (5% liquid) 1 〃 Antifoaming agent (5% liquid) 1 〃 Top coat is as below The formulation shown was prepared by mixing and stirring. Preparation of top coat paint Sodium silicate aqueous solution (40% liquid)
100 [parts by weight] Water 100 〃 Surfactant (5% liquid) 1 〃 Antifoaming agent (5% liquid) 1 〃 (2) Painting Apply the undercoat to a calcium silicate board (thickness 3 mm) twice by air spraying. The film was coated separately to a dry film thickness of approximately 50 μm, and primary drying was performed at 80° C. for 10 minutes. Next, the coated board with the top coat is air sprayed to a dry film thickness of approximately 5.
It was coated to a thickness of μm, and secondary drying was performed at 130°C for 3 hours. This was added to an aqueous ammonium phosphate solution at 30°C (monohydric ammonium phosphate 2.5
%, and diammonium phosphate 2.5%, PH
6.5) for 8 hours, further immersed in water for 12 hours, washed with water, and dried at 80°C. Example 2 (Example) (1) Preparation of paint A paint was prepared in the same manner as in Example 1 except that the formulation was changed as shown below. Preparation of undercoat paint Sodium silicate aqueous solution (40%) 60 [parts by weight] Potassium silicate aqueous solution (30% liquid) 40 〃 Aluminum polyphosphate 10 〃 Zinc oxide 10 〃 Silica powder 50 〃 Potassium pyrophosphate 2 〃 Aerosil 0.5 〃 Red iron 10 〃 Water 80 〃 Surfactant (5% liquid) 1 〃 Antifoaming agent (5% liquid) 1 〃 Top coat paint was prepared by mixing and stirring using the formulation shown below. Preparation of top coat paint Sodium silicate aqueous solution (40% liquid)
100 [parts by weight] Red iron 10 〃 Potassium pyrophosphate 0.5 〃 Water 100 〃 Surfactant (5% liquid) 1 〃 Antifoaming agent (5% liquid) 1 〃 (2) Painting Apply the undercoat paint to an asbestos slate board (3 mm thick) ) with air spray to a dry film thickness of approximately 40 μm, leave it in the air for 30 minutes, and then apply air spray to a painted board that has been primed with top coat paint to a dry film thickness of approximately 10 μm. Paint it so that
Drying was carried out at 120°C for 5 hours. This was immersed for 6 hours in an ammonium phosphate aqueous solution at 40°C (adjusted the pH value to 7.0 by blowing ammonia gas into a 5% phosphoric acid solution), and then immersed in a 0.5% saline solution for 5 hours.
After soaking for an hour, it was washed with water and dried in the air. Example 3 (Example) (1) Preparation of paint A coating material was prepared in the same manner as in Example 1 except that the formulation was changed as shown below. Preparation of undercoat paint Sodium silicate aqueous solution (40% liquid) 65 [parts by weight] Potassium silicate aqueous solution (30% liquid) 20 〃 Lithium silicate aqueous solution (25% liquid) 15 〃 Magnesium polyphosphate 15 〃 Zinc polyphosphate 10 〃 Alumina powder 40 〃 Synthetic mica 10 〃 Sodium pyrophosphate 2 〃 Cobalt blue 10 〃 Water 90 〃 Surfactant (5% liquid) 1 〃 Antifoaming agent (5% liquid) 1 〃 Top coat paint was prepared by mixing and stirring using the formulation shown below. . Preparation of topcoat paint Sodium silicate aqueous solution (40% liquid) 50 [parts by weight] Potassium silicate aqueous solution (30% liquid) 50 [parts by weight] Water 100 〃 Surfactant (5% liquid) 1 〃 (2) Painting Undercoat paint The coating was applied to a calcium silicate plate (4 mm thick) using air spray so that the dry film thickness was approximately 50 μm, and after being left in the air for 10 minutes,
The top coat was applied to a primed painted board by air spraying to a dry film thickness of approximately 10 μm, and dried at 130°C for 90 minutes. This was placed in an ammonium phosphate aqueous solution at 30°C (the pH value was adjusted to 8.0 by adding concentrated ammonia water to a 5% phosphoric acid solution).
After being immersed in water for 8 hours, and further immersed in 1% saline for 4 hours, it was washed with water and dried in the air. Comparative Example 1 (Example) (1) Preparation of paint Same as Example 1 (2) Painting The same painting as in Example 1 was carried out using a 5% phosphoric acid solution as the chemical treatment liquid. Comparative Example 2 (Example) (1) Preparation of paint Same as Example 1 (2) Painting Same painting as in Example 1 using 5% monoammonium phosphate aqueous solution (PH value 2) as the chemical treatment liquid I did this. Comparative Example 3 (Example) (1) Preparation of paint Same as Example 1 (2) Painting In Example 1, ammonium phosphate aqueous solution (concentrated ammonia water was added to 5% phosphoric acid solution and the pH value was 10.5) was used as the chemical treatment liquid. A similar coating was performed using The coating films of the above-mentioned Examples 1 to 3 and Comparative Examples 1 to 3 were tested according to the test method described later, and the results are shown in the table below.

[Table] ○: Good, △: Slightly bad, ×: Bad
The test method for the above coating film performance is as follows. (1) Water resistance: Immersed in water at 20℃ for 240 hours. (2) Accelerated weather resistance: Irradiated for 500 hours with a sunshine weather meter. (3) Boiling water resistance: Immersed in boiling water at 100℃ for 5 hours. (4) 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, and perform 10 cycles. (5) Stain resistance: Apply Vaseline mixed with 10% carbon black, leave it for a day, then wipe it off with gauze soaked in soapy water. (6) Gloss: Visual inspection (7) Acid resistance: Apply 10% HCl aqueous solution for 15 minutes. (8) Against alkalinity: Apply 10% NaOH aqueous solution for 15 minutes. (9) Adhesion: Goban test (100 pieces of 2 x 2 mm) (10) Maximum crack width: Measured using an electron microscope after being left in the air for 3 months. Example 4 Instead of the ammonium phosphate aqueous solution in Example 1, ammonia gas was blown into a 5% by weight aqueous solution of (1) ammonium sulfate, (2) ammonium nitrate, (3) ammonium chloride, or (4) ammonium acetate to adjust the PH value. Example 1 was immersed in a 30°C aqueous solution adjusted to 7 for 10 hours, and the other conditions were the same.
The process was repeated. The coating films of each of the obtained coatings were tested for boiling water resistance, efflorescence resistance, stain resistance, and gloss, and as a result, there were no abnormalities in all of them, and the gloss was good.

Claims (1)

[Claims] 1. A water-soluble alkali metal silicate-based aqueous solution paint for undercoat containing powder solids is applied onto a mineral substrate, dried appropriately, and then the undercoat paint is The PH value of a coated film coated with a water-soluble alkali metal silicate-based aqueous paint containing substantially little to no powder solids and dried appropriately.
A method for forming an inorganic coating film, which comprises applying an aqueous solution of an acid/ammonium salt of 3.5 to 10.0, washing with water, and drying. 2. The method of forming a coating film according to claim 1, wherein at least the undercoating coating material of the coating material contains an effective amount of a curing agent. 3 The pH of the acid/ammonium salt aqueous solution is 4 to 9.
A method for forming a coating film according to claim 1 or 2, which is within the range of. 4. Claims 1 and 2, wherein the amount of the powder solid content contained in the undercoating paint ranges from 20% by weight or more to the amount retained as a paint in the silicate aqueous solution vehicle. Or the method for forming a coating film according to Section 3. 5. The method for forming a coating film according to any one of claims 1 to 4, wherein the water used for washing is a dilute aqueous solution of a strong base/strong acid salt.