JPH0764596B2 - Composition for forming a translucent, low-reflective inorganic film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is intended to reduce the light reflectivity of a surface of a transparent product such as a glass product or a translucent ceramic product while maintaining the translucency thereof. The present invention relates to a film-forming composition used for forming a light-transmitting, low-reflecting durable inorganic film on the surface of the above transparent product.

Further, this composition is also used for forming a light-transmitting and low-reflecting colored film by adding a coloring agent thereto.

In this way, the inorganic film that reduces the light reflectivity of the surface without impairing the translucency, for example, in window glass, bottle glass, lighting equipment outer glass, lamp glass, and various translucent ceramic products. , Is formed for the purpose of providing a matte or matt coloring.

(Prior Art) As a method of making the surface of glass or translucent ceramics low-reflecting, the surface is polished with an abrasive or shot blasted to make the surface uneven, or the surface is chemically treated with hydrofluoric acid or the like. There are methods such as a method of etching to make the surface uneven, and a method of applying an organic coating to the surface to make the surface uneven.

(Problems to be Solved by the Invention) However, each of these methods has the following problems. That is, in the method of polishing the surface or shot blasting, the shape of the object to be processed is limited to a flat plate,
Moreover, the object to be processed is easily damaged because it is subjected to mechanical shock.
In the chemical etching method, since a dangerous substance such as hydrofluoric acid is used as the etching solution, there is a problem in management of the processing solution and safety in work. In the method of applying an organic coating, the hardness and durability of the film are insufficient.

An object of the present invention is to provide a film-forming composition capable of overcoming all the above problems.

(Means for Solving the Problems) As a result of repeated studies to achieve the above object, the present inventors have used an aqueous solution containing alkali silicate as a main component as a binder for forming a light-transmitting film, and have a refractive index of alkali silicate. (1.49
By blending an inorganic filler having a refractive index (1.48 to 1.60) close to ~ 1.54) with the above binder, light scattering at the interface between the binder and the filler is reduced, and a translucent film is formed. By obtaining the finding that a composition can be obtained, and further controlling the compounding ratio of the filler in the composition and the particle size of the filler to a required value, the degree of unevenness of the coating surface, that is, the surface roughness can be determined. With the knowledge that it is possible to obtain a composition that can be adjusted to form a film with low reflectivity,
The present invention has been completed.

That is, the present invention provides an alkali silicate 100 represented by the general formula R ₂ O.nSiO ₂ (R is an alkali metal, n is a number of 0.5 or more).
Parts, an average particle diameter of 1 to 20 μm, and an inorganic film forming composition containing 5 to 70 parts of an inorganic filler having a refractive index in the range of 1.48 to 1.60 and a curing agent.

In the present specification, all parts expressing ratios are on a weight basis.

Examples of alkali silicates include commercially available liquid products such as water glasses No. 1, No. 2, No. 3, No. 3, potassium silicate, lithium silicate, and colloidal silica-modified sodium silicate. These alkali silicates may be used alone or in combination of two or more.

Preferred examples of the inorganic filler material include albite (refractive index 1.52), anorthite (refractive index 1.58), sepiolite (refractive index 1.53), zeolite (refractive index 1.48), petalite (refractive index 1.51), etc. The fillers made of these materials are used alone or in combination of two or more.

When the average particle size of the filler is less than 1 μm, the irregularities on the surface of the film become small and low reflectivity cannot be obtained. On the other hand, if the average particle size of the filler is larger than 20 μm, irregularities on the surface of the coating become too large and the appearance is deteriorated, and the surface is easily soiled. Therefore, the average particle size of the filler is limited to the range of 1 to 20 μm. A particularly preferable range of the average particle size of the filler is 3 to 15 μm.

When the ratio of the filler to 100 parts of alkali silicate is less than 5 parts, the unevenness of the film surface also becomes small and low reflectivity cannot be obtained. On the other hand, when this ratio is more than 70 parts, the film-forming ability of the composition decreases, and the strength and durability of the cured film deteriorate. Therefore, the ratio of the filler to 100 parts of alkali silicate is limited to the range of 5 to 70 parts. A particularly preferable range of this ratio is 10 to 50 parts.

As the curing agent, various known phosphates, colloidal silica, silicofluorides, polyvalent metal oxides, and other known curing agents can be used alone or in combination of two or more. The mixing ratio of the curing agent is appropriately selected within the range of 5 to 65 parts with respect to 100 parts of alkali silicate. By properly selecting the type and mixing ratio of the curing agent, the durability such as water resistance, acid resistance, and alkali resistance can be remarkably improved without impairing translucency.

The film-forming composition according to the present invention is applied as a paint in the form of an aqueous solution or an aqueous dispersion onto the surface of a light-transmitting coated article by a method such as spraying or dipping. The ratio of water to 100 parts of solid content of this composition is 10 to 300 parts, and the film thickness can be adjusted by increasing or decreasing the ratio of water. The applied aqueous composition is usually
By heating this at a temperature of 200 to 300 ° C. for 10 to 30 minutes, it is cured and a film having desired properties is formed.

The film-forming composition according to the present invention is used for forming a light-transmitting and low-reflecting colored film by adding a coloring agent thereto.

As the colorant, an appropriate amount of an inorganic pigment such as red iron oxide, cobalt blue, titanium yellow, or colored glass is used.

Typical examples of translucent coated products to which the film-forming composition according to the present invention should be applied include glass products such as window glass, bottle glass, glazing for lighting equipment, and glass for lamps, and various translucent ceramic products. And so on. Such a light-transmitting and low-reflecting inorganic film is formed, for example, for the purpose of subjecting the above-mentioned light-transmitting coated product to a matte or matte coloring treatment.

(Effects of the Invention) The film-forming composition according to the present invention contains an alkali silicate and an inorganic filler having a specific average particle size and a specific refractive index in a specific ratio, and further contains a curing agent. Therefore, it is possible to form a durable, inorganic film with a light-transmitting and low-reflecting property on the surface of transparent products such as glass products and light-transmitting ceramics products. The light reflectivity of can be reduced.

In this way, glass products such as window glass, bottle glass, glass for lighting fixtures, glass for lamps, and various translucent ceramic products can be subjected to a matte or matte coloring treatment.

(Example) Next, in order to demonstrate the above-mentioned effect, some examples of the present invention and comparative examples for showing a comparison therewith will be given.

Example 1 No. 3 sodium silicate 40% aqueous solution 100 parts Sepiolite 10 parts (refractive index 1.53 average particle size 10 μm) aluminum phosphate 12 parts water 100 parts The above composition was ground and mixed in a ball mill for 30 minutes to prepare a paint. This coating material was spray-coated on a transparent glass plate (coating amount: 70 g / m ² ) and baked and cured at 250 ° C. for 10 minutes to prepare Sample 1.

Example 2 A mixture of 100 parts of 20% aqueous sodium silicate solution and 10 parts of powdered colloidal silica was charged into a flask equipped with a reflux device, and the charged material was heated at 100 ° C. for 1 hour to cure the colloidal silica as a curing agent. A colorless and transparent modified sodium silicate aqueous solution was prepared.

100 parts of the above-mentioned modified sodium silicate aqueous solution 10 parts of soda lime glass powder (refractive index 1.51 average particle size 5 μm) 100 parts of water The above composition was ground and mixed for 30 minutes with a ball mill to prepare a paint. This paint is spray applied to a transparent glass plate (application amount: 70 g / m ² ) and baked and cured at 300 ° C for 15 minutes,
Sample 2 was prepared.

Example 3 No. 3 potassium silicate 40% aqueous solution 100 parts Borosilicate glass powder 15 parts (refractive index 1.50 average particle size 4 μm) aluminum phosphate 11 parts water 25 parts The above composition was ground and mixed in a ball mill for 30 minutes to prepare a paint. Was prepared. This paint is spray applied to a transparent glass plate (application amount: 80 g / m ² ), baked and cured at 300 ° C for 5 minutes,
Sample 3 was prepared.

Example 4 No. 4 sodium silicate 30% aqueous solution 100 parts albite 10 parts (refractive index 1.52 average particle size 12 μm) aluminum phosphate 8 parts water 10 parts The above composition was ground and mixed for 30 minutes with a ball mill to prepare a paint. did. This paint is spray applied to a transparent glass plate (application amount: 80 g / m ² ) and baked and cured at 250 ° C for 10 minutes,
Sample 4 was prepared.

Comparative Example 1 No. 3 sodium silicate 40% aqueous solution 100 parts Alumina 10 parts (refractive index 1.76 average particle size 5 μm) Aluminum phosphate 12 parts Water 20 parts A sample 5 was prepared by the same method as in Example 1. .

Comparative Example 2 No. 4 sodium silicate 30% aqueous solution 100 parts Aluminum phosphate 8 parts Water 10 parts Sample 6 was prepared in the same manner as in Example 1 using the above composition.

Comparative Example 3 No. 4 sodium silicate 30% aqueous solution 100 parts Borosilicate glass powder 10 parts Refractive index 1.50 Average particle size 0.5 μm) Aluminum phosphate 8 parts Water 30 parts By the same method as in Example 1 using the above composition. Sample 7 was prepared.

Performance test For each test piece obtained in the above Examples and Comparative Examples,
The test was conducted by the following method to evaluate the performance of the coating film.

1) The presence or absence of bubbles and cracks in the film appearance was evaluated by both visual observation and optical microscope observation.

2) Comparison of translucency was performed by the following method.

Place each sample on the white area of the concealment rate test paper certified by the Japan Paint Inspection Association, and apply a colorimeter (CR
Contacting the colorimetric unit -A10 type ") and L _w, values were measured a _w, b _w. Then the sample was transferred to a black portion of the test paper was measured values of L _b, a _{b, b b} in the same manner. The two color differences ΔE _wb were calculated by the following formula, and the translucency was determined. Here, the larger the value of ΔE _wb, the greater the translucency.

3) Low reflectivity was evaluated by measuring the 60 ° specular reflectance of the coating surface with a specular gloss measuring device (manufactured by Nippon Denshoku Industries Co., Ltd.).

4) Water resistance was evaluated by immersing the sample in water at room temperature for 7 days, drying it, and visually observing the change in the film appearance.

5) Hot water resistance is measured by immersing the sample in hot water at 70 ℃ for 10 hours,
It was evaluated by drying and visually observing the change in the film appearance.

6) The acid resistance was evaluated by immersing the sample in a 10% sulfuric acid aqueous solution at 25 ° C. for 10 hours, washing with water and drying, and visually observing the change in the appearance of the film.

7) Alkali resistance was evaluated by immersing the sample in a 10% aqueous sodium hydroxide solution at 25 ° C. for 10 hours, washing with water and drying, and visually observing changes in the film appearance.

The test results are summarized in Table 1.

As is clear from Table 1, according to the film-forming composition of the present invention, excellent inorganic substances in all items of bubbles and cracks, translucency, low reflectivity, water resistance, warm water resistance, acid resistance and alkali resistance. It will be appreciated that a film can be formed.

Claims (2)

[Claims] 1. The general formula R ₂ O.nSiO ₂ (R is an alkali metal, n
Is a number of 0.5 or more) 100 parts of alkali silicate, an average particle size of 1 to 20 μm, an inorganic filler of 5 to 70 parts having a refractive index of 1.48 to 1.60, and a light-transmitting low reflection containing a curing agent. Composition for forming a hydrophilic inorganic film. 2. The composition according to claim 1, wherein the inorganic filler is a granular material comprising at least one selected from the group consisting of glass, albite, anorthite, zeolite, sepiolite and petalite.