JPH09241531A - Inorganic coating composition and method for forming inorganic coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inorg. coating compsn. which is applied to a substrate, dried, brought into contact with an alkali removal treatment soln., washed, and surface cracks with narrow widths, hardly exhibiting efflorescence. and having a high water permeability by dispersing a specific silicate powder in a specific aq. silicate soln. SOLUTION: This compsn., which is applied to a substrate, dried, brought into contact with an alkali removal treatment soln., washed, and dried to form an inorg. coating film, is an aq. soln. of a water-sol. alkali metal silicate contg. a powder of a water-sol. alkali metal silicate dispersed therein in an amt. of 5-50wt.% of the dissolved water-sol. alkali metal silicate. Sodium or potassium silicate is pref. as the water-sol. alkali metal silicate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for forming a siliceous inorganic coating film on a surface of a substrate and a coating film forming method using the same, and in particular, to a water-soluble alkali metal silicate. The present invention relates to a composition for forming the coating film and a coating film forming method. More specifically, the present invention relates to a composition for forming an inorganic coating film having a small crack width generated on the surface, little white sinter, and good water permeability, and a coating film forming method.

[0002]

2. Description of the Related Art A method for forming a siliceous inorganic coating film by applying an aqueous solution of a water-soluble alkali metal silicate such as sodium silicate to the surface of a substrate and subjecting it to dealkalization is disclosed in Japanese Examined Patent Publication No. 64-8593. And the like are known.

The method of the above publication is such that a coating material containing a water-soluble alkali metal silicate or the like is undercoated and treated with an acid solution,
This is a method in which the paint is overcoated and cured after the acid is removed by washing.

As an improvement on this, a water-soluble alkali metal silicate aqueous solution paint (undercoating paint) containing powder solids is applied and appropriately dried, and then the content of the powder solids is reduced. There is a method of applying a silicate-based aqueous solution coating (top coating) that does not contain powder solids or a smaller amount than that of the undercoating coating, and appropriately drying it, then treating with an acid / ammonium salt-based aqueous solution, washing with water, and drying. (Japanese Patent Publication 62-
39027).

Further, there is a method in which the undercoat paint is heated and dried at an appropriate speed, then the topcoat paint is applied, the temperature is dried at an appropriate speed, and treatment with an acid / ammonium salt aqueous solution is performed, followed by washing and drying. Proposed (Japanese Patent Publication No. 3-18514)
Issue). In this method, the crack width of the coating film is 0.4 to
It becomes about 0.8 μm, and the stain resistance can be exhibited around water.

A method is also known in which an undercoat paint is dried, treated with an acid / ammonium salt aqueous solution, washed with water, dried, and then coated with an overcoat paint, treated with the aqueous solution, washed with water and dried. 2-36311).

[0007] Conventionally, a filler is added to the paint in order to suppress shrinkage. As the filler, silica stone, alumina, glass powder, clay, mica, asbestos,
Glass fiber etc. are mentioned. Further, a pigment added for coloring also acts as a filler.

[0008]

A coating film formed by these known methods for forming an inorganic coating film has a relatively large width of cracks formed on the surface thereof, and thus contaminants are likely to adhere to the coating film. There was an improvement task.

There is also a problem that the white flower component in the base material is likely to be eluted on the surface of the coating film to cause the white flower phenomenon.

It is an object of the present invention to provide a composition for forming an inorganic coating film having a small crack width on the surface, less whitening and good water permeability, and a coating film forming method using the same. .

[0011]

The composition for forming an inorganic coating film of the present invention is obtained by applying an aqueous solution of a water-soluble alkali metal silicate to the surface of a substrate, drying it, and then contacting it with a solution for dealkalizing treatment. In the composition for forming an inorganic coating film used for forming an inorganic coating film on the surface of a substrate having a step of washing with water and then drying, a water-soluble alkali metal silicate in an aqueous solution is used. 5 powders of metal silicate for dissolved water-soluble alkali metal silicate
It is characterized by being dispersed in an amount of up to 50% by weight.

The method for forming an inorganic coating film of the present invention is
Such a composition for forming an inorganic coating film of the present invention is applied to the surface of a substrate, dried, then brought into contact with a dealkalizing solution, washed with water, and then dried.

The water-soluble alkali metal silicate powder dispersed in the aqueous solution of the water-soluble alkali metal silicate first exhibits the effect as a filler, and can reduce the crack width and the crack length. Moreover, the water-soluble alkali metal silicate powder exerts a great effect particularly in suppressing the amount of water permeation. This is because the alkali metal silicate powder, which is a solid powder, suppresses the growth of cracks, and is partially dissolved in a water-soluble alkali metal silicate aqueous solution that is a homogeneous matrix, and its concentration, It is considered that this is because the viscosity is increased and the coating film is densified. Since the water permeability is suppressed in this way, the white flower component is prevented from being eluted from the base material, and the white flower resistance that has not been obtained is exhibited.
Further, since the matrix and the filler are homogeneous alkali metal silicates, diffuse reflection of light does not occur at the coating surface layer,
Despite the addition of the filler, the coating film does not lose transparency, and good gloss can be obtained.

On the other hand, with the conventional fillers used conventionally, the effect of suppressing cracks can be obtained, but since the matrix and the fillers have different refractive indices, the transparency of the coating film is reduced. Will be lost.

In the present invention, the water-soluble alkali metal silicate is preferably sodium silicate or potassium silicate.

The dealkalizing solution is preferably an aqueous solution of one or more ammonium salts, phosphates and oxalates.

[0017]

Embodiments of the present invention will be described below in detail.

First, the composition for forming an inorganic coating film of the present invention will be described.

In the present invention, the composition for forming an inorganic coating film, that is, the coating composition is a water-soluble alkali metal silicate or a modified water-soluble alkali metal silicate obtained by modifying the water-soluble alkali metal silicate with a polyvalent metal compound. Water-soluble alkali metal silicate powder, and if necessary, additives such as curing agent, filler, pigment, surfactant, dispersant, defoaming agent, thickener, etc., in an aqueous solution of the mixture, and concentration. The water for adjustment is prepared by adding the following composition.

Water-soluble alkali metal silicate aqueous solution: 100 parts by weight Water-soluble alkali metal silicate powder: 5 to 50 wt% curing agent based on the water-soluble alkali metal silicate dissolved in the water-soluble alkali metal silicate aqueous solution : 10 parts by weight or less Filler: 50 parts by weight or less Pigment: 50 parts by weight or less Other additives: 5 parts by weight or less Water: 0 to 200 parts by weight Water-soluble alkali metal silicate aqueous solution and water-soluble alkali metal silicate powder Examples of the water-soluble alkali metal silicate include lithium silicate, sodium silicate, potassium silicate, and the like, but it is preferable to use sodium silicate, potassium silicate, and particularly sodium silicate in terms of film-forming property, coating property, cost and the like. .

It should be noted that the water-soluble alkali metal silicate of the water-soluble alkali metal silicate aqueous solution and the water-soluble alkali metal silicate of the water-soluble alkali metal silicate powder are effective even in the case of different alkali metal silicates. However, it is preferable to use the same one.

The water-soluble alkali metal silicate aqueous solution has a water-soluble alkali metal silicate concentration of 7% by weight or more, particularly 1
It is preferably 0% by weight or more, and particularly preferably 15 to 60% by weight. The amount of the water-soluble alkali metal silicate powder added is 0.5 to 50 with respect to the water-soluble alkali metal silicate in the water-soluble alkali metal silicate aqueous solution, that is, the dissolved water-soluble alkali metal silicate. Weight% Even if the amount of the water-soluble alkali metal silicate powder added is less than 0.5% by weight or more than 50% by weight, the effect of the present invention due to the addition of the water-soluble alkali metal silicate powder cannot be sufficiently obtained. In the present invention, it is particularly preferable that the total amount of the water-soluble alkali metal silicate dissolved and dispersed in the paint is about 5 to 80% by weight.

As the curing agent, polyvalent metal oxides such as zinc oxide, magnesium oxide and aluminum oxide; polyvalent metal hydroxides such as magnesium hydroxide and aluminum hydroxide; polyvalent metals such as zinc carbonate and magnesium carbonate. Carbonates;
There are polyvalent metal phosphates such as magnesium phosphate, aluminum phosphate and zinc phosphate; silicofluorides such as zinc silicofluoride and aluminum silicofluoride; organic compounds such as glyoxal and oxalic amide. One or more curing agents are used.

As the filler, granular materials such as silica stone, alumina and glass powder; flat materials such as clay and mica; fibrous materials such as asbestos and glass fiber powder are used.

As the pigment, titanium dioxide, red iron oxide, yellow lead, chrome green, ultramarine, mars violet, cobalt blue, carbon black and the like are used.

The coating material according to the present invention may be composed of an undercoating material which is directly applied to a base material and an overcoating material which is applied to a base material coated with this undercoating material.

Next, a method for forming an inorganic coating film of the present invention using such a composition for forming an inorganic coating film of the present invention will be described.

In the present invention, the base material for forming the inorganic coating film is not particularly limited, and it may be porous or non-porous, and all inorganic and organic moldings can be used. As typical examples, 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, SFRC (steel fiber reinforced cement) board, ALC board, rock wool inorganic molded body, metal plate, ceramic plate, glass plate and the like can be mentioned.

In the present invention, first, a coating material is applied onto such a base material and dried.

The paint can be applied by spraying, dipping, a roll coater, a curtain coater or the like.

Further, the drying after the coating of the paint is 40 to 150.
It is carried out at 1 ° C. for about 1 minute to 48 hours.

The thickness of the coating film thus formed is 2
It is preferably 0 to 250 μm.

When the undercoat paint and the topcoat paint are used, the undercoat paint may be applied and then dried, and then the topcoat paint may be applied and then dried.

In this case, the thickness of the undercoat coating film is 20-25.
The thickness of the top coating film is preferably 0 μm and 50 μm or less.

After the coating material has been applied and dried in this manner, it is brought into contact with a dealkalizing solution to carry out dealkalization. The dealkalization treatment may be carried out after the undercoat paint has been applied and dried and before the topcoat paint has been applied.

In the dealkalizing treatment, as the dealkalizing treatment solution, an aqueous solution of various organic acid salts or inorganic acid salts can be used. Particularly, ammonium salt,
One or more of phosphates and oxalates, specifically, sodium phosphate, sodium hydrogenphosphate, potassium phosphate, potassium hydrogenphosphate, ammonium phosphate,
It is preferable to use an aqueous solution of ammonium hydrogen phosphate, sodium oxalate, potassium oxalate, ammonium oxalate, ammonium chloride, ammonium acetate, ammonium iodide, or the like, especially an aqueous solution of ammonium phosphate.

The dealkalizing solution has a pH of 3.5.
-10, the salt concentration is preferably 1 to 20% by weight, and the liquid temperature is preferably in the range of room temperature to 60 ° C.

The treatment time with such a dealkalizing solution, that is, the contact time, varies depending on the type of the substrate used, the type of coating material, the coating conditions, the subsequent drying conditions, etc. It is preferably 8 hours.

The contacting step can be carried out by a dipping method in which the base material is dipped in the processing solution, or a curtaining method or a coating method in which the processing solution is poured onto the base material. In this contacting step, the base material does not necessarily have to be placed horizontally and may be leaned against it.

After such dealkalization treatment, the substrate is washed with water and dried according to a conventional method to obtain a substrate having an inorganic coating film formed thereon.

[0041]

The present invention will be described more specifically below with reference to examples and comparative examples.

Examples 1 to 6 and Comparative Examples 1 to 3 Paints were prepared by mixing and stirring in the following formulation.

Preparation of paint (parts by weight) Sodium silicate aqueous solution (40% by weight liquid) 100 Water 100 Surfactant (5% by weight liquid) 1 Defoaming agent (5% by weight liquid) 1 Sodium silicate powder in sodium silicate aqueous solution The ratio shown in Table 1 with respect to sodium silicate This coating material was applied to a cementitious base material (thickness: 10 mm) by air spraying so that the film thickness after drying would be about 30 μm, and put into an atmosphere of 135 ° C. And held for about 1 hour to dry. Next, it is immersed for 120 minutes in an ammonium phosphate aqueous solution (first ammonium phosphate: 7.5% by weight, second ammonium phosphate: 7.5% by weight, 40 ° C.) having a pH of 6.5, and then immersed in water. After soaking for 30 minutes and washing with water, 80 ℃
And dried.

The performance of the coating film formed was examined by the following method, and the results are shown in Table 1.

Maximum crack width It was observed and measured by an electron microscope. ○ 1μm or less
And those exceeding 1 μm were marked with x.

Water permeation resistance A test piece is held horizontally according to JIS A6910, and a funnel having a diameter of about 75 mm is fixed upside down on the test piece with a sealing agent. Next, the funnel was filled with water and the amount of water permeation up to 24 hours was measured. If 1.5 ml or less is marked ○,
Those exceeding 1.5 ml were marked with x.

White flower resistance The back side of the sample is left for 1 day in a wet state and then air-dried for 1 day, which is defined as 1 cycle and 10 cycles are performed. The case where there was no abnormality was marked as ◯, and the case where white flower was generated was marked as x.

[0048]

[Table 1]

Comparative Examples 4 to 31 A coating film was prepared in the same manner as in Example 1 except that silica silicate, alumina, glass or titanium white powder was used in the proportions shown in Tables 2 to 5 instead of the sodium silicate powder. It formed, and the measurement result of the performance is shown in Tables 2-5.

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

[Table 4]

[0053]

[Table 5]

Examples 7 to 12 and Comparative Examples 32 to 34 Instead of sodium silicate powder, potassium silicate powder was used in Table 6.
A coating film was formed in the same manner as in Example 1 except that the ratio was used as shown in Table 1, and the measurement results of the performance are shown in Table 6.

[0055]

[Table 6]

Examples 13 to 18, Comparative Examples 35 to 37 Examples except that an aqueous potassium silicate solution was used instead of the sodium silicate aqueous solution, and potassium silicate powder was used instead of the sodium silicate powder in the proportions shown in Table 7. A coating film was formed in the same manner as in No. 1, and the measurement results of the performance are shown in Table 7.

[0057]

[Table 7]

Examples 19 to 24, Comparative Examples 38 to 40 The same as Example 1 except that 5 parts by weight of titanium white was further mixed in and the sodium silicate powder was used in the proportion shown in Table 8 in the preparation of the paints. Was performed to form a coating film, and the measurement results of the performance are shown in Table 8.

[0059]

[Table 8]

[0060]

As described in detail above, according to the composition for forming an inorganic coating film and the method for forming an inorganic coating film of the present invention, the occurrence of cracks or white sinter that deteriorates the stain resistance is suppressed, A good glossy inorganic coating film can be formed.

In the present invention, the water-soluble alkali metal silicate is preferably sodium silicate or potassium silicate.

The dealkalizing solution is preferably an aqueous solution of one or more ammonium salts, phosphates and oxalates.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuko Kitamura 5-1-1 Koiemotocho, Tokoname City, Aichi Prefecture Inax Co., Ltd.

Claims (4)

[Claims] 1. A surface of a substrate having a step of coating an aqueous solution of a water-soluble alkali metal silicate on the surface of the substrate, followed by drying, contact with a solution for dealkalizing treatment, washing with water, and then drying. In a composition for forming an inorganic coating film used for forming an inorganic coating film on a water-soluble alkali metal silicate powder, a water-soluble alkali metal silicate powder is dissolved in an aqueous solution of a water-soluble alkali metal silicate. A composition for forming an inorganic coating film, characterized by being dispersed in an amount of 5 to 50% by weight with respect to a salt. 2. The composition for forming an inorganic coating film according to claim 1, wherein the water-soluble alkali metal silicate is sodium silicate or potassium silicate. 3. An inorganic coating film having a step of applying the composition of claim 1 or 2 to a surface of a substrate, followed by drying, contact with a dealkalizing solution, washing with water, and then drying. Forming method. 4. The inorganic material according to claim 3, wherein the dealkalizing solution is one or more aqueous solutions selected from the group consisting of ammonium salts, phosphates and oxalates. Method of forming coating film.