JPH04325444A - Coating composition for frosting glass - Google Patents

Abstract

PURPOSE:To provide a coating compsn. for frosting capable of frosting glass without etching the surface of the glass, unnecessitating the treatment of waste liquor and capable of arbitrarily controlling the total light transmissivity of frosted glass in the range of >=60% and the diffusion transmissivity in the range of 5-90%. CONSTITUTION:At least one kind of inorg. oxide selected from among SiO2, Al2O3, BaSO4, CaSO4, CaCO3, ZnO and ZrO2 is dispersed in a solvent contg. a dissolved binder to obtain a coating compsn. for frosting.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a coating composition used for frosting a glass surface, and more particularly to a coating composition for frosting a glass surface.
, CaSO4, CaCO3, ZnO, and ZrO2, the present invention relates to a frosted coating composition in which at least one selected from among , CaSO4, CaCO3, ZnO, and ZrO2 is dispersed in a solvent in which a binder is dissolved. The frosted coating composition of the present invention has the feature that the total light transmittance is 60% or more, the diffused transmittance can be arbitrarily controlled from 5 to 90%, and it can be frosted without damaging the glass surface that serves as the substrate. .

0002

[Prior Art] Conventionally, as a frosting method, (1)
Corrosion method using hydrofluoric acid aqueous solution (2) Sandplast method (3) Method of painting and baking a coating agent mainly composed of alkoxysilane (for example, JP-A-58-
74541, JP-A-02-172844) is known.

[0003] In (1) and (2), the glass surface is made rough by chemically corroding it or physically scraping it off, which may reduce the glass strength. Also,
Nowadays, the use of coating glass surfaces with functional thin films such as ultraviolet absorbing films is increasing, but when coating such functional thin films, frosting using methods (1) and (2) cannot be performed. Furthermore, these processes are expensive and cannot be applied to surfaces with complex shapes. Moreover, if oil or the like adheres to this rough surface, the diffused reflection will be reduced and the surface will become transparent, and the surface will be roughened, causing problems such as dust and staining. Furthermore, in (1), harmful waste liquid such as hydrofluoric acid is generated. In (3),
It is difficult to obtain a sufficient haze value, it is difficult to increase the thickness of the film, and there are problems such as large irregularities on the glass surface.

0004

SUMMARY OF THE INVENTION An object of the present invention is to provide a frosting coating composition for glass that does not corrode the glass surface and does not require waste liquid treatment, and which has a total light transmittance of 60%. Above, the diffuse transmittance is 5 to 90.
The objective is to provide a coating composition that can be arbitrarily controlled up to %.

[0005]

[Means for solving the problem] The above purpose is to
, Al2 O3 , BaSO4 , CaSO4 , C
This is achieved by a frosted coating composition characterized in that at least one compound selected from aCO3, ZnO, and ZrO2 is dispersed in a solvent in which a binder is dissolved.

The coating of the present invention is composed of a specific inorganic oxide filler, a binder solvent, and various additives as required. The inorganic oxide filler is S
iO2, Al2O3, BaSO4, CaSO4
, CaCO3, ZnO and ZrO2, which have a tortuosity of 1.4 to 2.8. Among these inorganic oxide fillers, those with a particle size of 0.01 to 10
It is preferably in the range of μm, particularly in the range of 0.2 to 0.4 μm. The reason why particles having a particle size within this range is preferable is as follows.

Glasses with an opaque appearance include the following two types:
There are two types. One is frosted or frosted glass. This type of glass only has an opaque appearance as a result of light being scattered by diffuse reflection on the surface, and the reflectance itself is not particularly large, so the amount of transmitted light is much different from that of ordinary glass. There is no decrease in brightness. The other is opalescent or alabaster glass. In this type of glass, scattering due to diffuse reflection occurs primarily within the glass rather than on the surface, and the degree of scattering is higher than that of frosted glass, giving a more uniform transmitted light.

[0008] As described above, the light scattering process has a great influence on the opacity of glass. When light enters a material, energy is lost due to reflection or absorption on the surface of the material, and the remainder is transmitted. According to the Lambert-Beer law, the transmitted light (T) is T=I/Io=(1-R)2 exp(-βt)Io:
Incident light, I: transmitted light, R: reflectance, β: apparent attenuation coefficient, t: film thickness. Assuming that the refractive index of air is 1, the reflectance R of the surface material is expressed as R=[(n-1)/(n+1)]2 n: refractive index according to Fresnel's law. n is a value specific to the substance, and in the present invention is determined by the substance forming the inorganic oxide filler. Further, the apparent attenuation coefficient β is determined by absorption and scattering of the substance itself. Therefore, assuming that the apparent attenuation coefficient is 0, and finding the conditions for T>0.6, we find that n<2.8
becomes.

Regarding scattering, when light enters a substance, electrons are excited to the high-level conduction band, so light corresponding to the energy gap is absorbed, and scattering occurs when the light returns to the low-level. This scattering is treated as Rayleigh scattering when the wavelengths of the incident light and the scattered light match, the phases are continuous, and the wavelength is sufficiently small relative to the size of the scattering center. Rayleigh scattering is expressed by the following equation. Ks=(4π5/3λ4)・d6・[(
M2 −1)/(M2 +2)]2 Ks: scattering coefficient,
λ: wavelength, d: particle diameter M=n1/n0,
n0: refractive index of substrate, n1: refractive index of dispersed material

For the same substance, scattering depends on the particle size and wavelength of the powder, and can be calculated by Rayleigh diffraction scattering. Generally, powder with a particle size of 1/2 of the wavelength causes the most obvious scattering. wake up From this, visible light region (800 nm ~
The particle size at which scattering is maximum at 400 nm) is 0.2 to 0.
．． It becomes 4 μm. Therefore, deviating from this particle size,
When the particle size becomes smaller than the wavelength, scattering rapidly decreases in proportion to the sixth power of the particle size, resulting in transparency, according to the Rayleigh scattering equation. On the other hand, if the particle size deviates from this range and becomes larger than the wavelength, the total light transmittance will drop significantly and the film strength of the coating will drop significantly. However, in general, powder is secondary agglomerated and is completely unilateral.
It is very difficult to grind down to the next particle size. Accordingly, in the present invention, the diffused transmittance is controlled by adjusting the particle size of the inorganic oxide that undergoes gradual secondary aggregation to the above range using an appropriate disperser.

The binder is not particularly limited as long as it adheres closely to the glass and forms a strong film. When coating on a glass surface used at room temperature, the following organic polymers or inorganic compounds can be used as a binder. Butyral resin; Acrylic resin; Fluorine resin; Silicone resin; Urethane acrylate type and other U
V-curing resin; urethane resin; melamine resin; silicone acrylic resin; silicone alkyd resin; alkali silicate such as sodium silicate; inorganic colloid such as silica sol and alumina sol; alkyl silicate such as tetraethoxysilane; such as aluminum phosphate Phosphate; metal alkoxide, aluminum chelate,
Metal compounds such as tin acetate.

[0012] When coating on a glass surface used at high temperatures, silicone resins, which have good heat resistance among the binders; silicone acrylic resins; silicone alkyd resins; sodium silicate; inorganic colloids; phosphates;
A metal compound or the like is used as a binder. In particular, it is desirable to use a silicone resin having the following structure.

[Chemical formula 1] R is an alkyl group, a phenyl group X is an alkyl group, phenyl group, alkoxy group, hydroxyl group

[
[0013] In the composition of the present invention, the blending ratio of the inorganic oxide constituting the film and the binder is usually 1 to 500 parts by weight, more preferably 5 to 100 parts by weight, per 100 parts by weight of the binder. The range is set to . By controlling the ratio of the inorganic oxide to the binder and the dispersion stability, the diffusion transmittance of the coating film is controlled. Therefore, if the amount of the inorganic oxide is less than the above range, the diffuse transmittance of the coating cannot be controlled. Conversely, if the amount of inorganic oxide is greater than the above range, the total light transmittance of the coating will fall below 60%.

[0014] In the present invention, the coating usually has a thickness of 0.1 to 1
The film thickness is preferably in the range of 0.00 μm, preferably 0.5 to 5 μm. If the film thickness of the film is thinner than 0.1 μm, pinholes are likely to occur in the film; conversely, if the film thickness is less than 100 μm,
If it is thicker, its total light transmittance will decrease and the adhesion of the coating to the glass substrate will be impaired.

Any solvent may be used as long as it dissolves the binder used. However, this solvent preferably has a boiling point of 60 to 200°C so that drying can be performed at low temperatures. Such solvents include aromatic hydrocarbons such as xylene and toluene; alcohols such as n-butanol; esters such as butyl acetate; ketones such as methyl isobutyl ketone; and glycol ethers such as ethyl cellosolve. ;
Saturated hydrocarbons such as n-hexane, ligroin, mineral spirits; water. Of course, depending on the solvent, it is also possible to form a film by drying at room temperature. The amount of solvent in the composition can be set appropriately depending on the viscosity of the composition, coating method, etc., but generally 2.
It is 0 to 95% by weight.

[0016] Additives that may be used as necessary include:
Silane compounds for surface modification of inorganic oxides, thickeners for adjusting the viscosity of coatings, paint fillers, dispersants, lubricants, desiccants, antifoaming agents, curing agents, surface smoothing agents etc.

As for the method of frosting glass with the composition of the present invention, that is, the method of applying it to glass, any method may be used as long as it is possible to uniformly apply the coating agent. Examples include a spin coating method, a spray method, a dipping method, a curtain flow flow coating method, and a brush coating method. The viscosity of the coating agent varies depending on the coating method, so the viscosity of the coating agent is adjusted by using an appropriate amount of solvent or adding a thickener.

[0018]

[Examples] The present invention will be specifically described below with reference to Examples. Example 1 100 parts by weight of tetraethoxysilane, 100 parts by weight of methyltrimethoxysilane, 50 parts by weight of isopropyl alcohol, and 50 parts by weight of 0.1N hydrochloric acid were mixed, and at 60°C, 2
After reacting for an hour with stirring, use "organosilica sol" (manufactured by Nissan Chemical Industries, Ltd., isopropanol silica sol, SiO2 content 30%) as a binder for 200
Added parts by weight. 8 parts by weight of SiO2 having a particle size of 0.5 to 5 μm was blended with 100 parts by weight of the obtained binder solution and dispersed in a sand grinder for 20 minutes to prepare a coating agent. This coating agent was applied to a glass plate by spin coating, and dried at 200° C. for 20 minutes to form a frosted film with a thickness of 2 μm. In this way, a frosted glass with a total light transmittance of 95% and a diffuse transmittance of 80% was obtained. Even when this glass substrate was continuously heated at 500° C. for 1000 hours, no change was observed in the above effect.

Example 2 100 parts by weight of silicone acrylic resin (nonvolatile content 50%), 100 parts by weight of xylene A with a particle size of 0.1 to 0.3 μm
30 parts by weight of l2O3 was blended and dispersed using a sand grinder for 1 hour. A film of this coating agent was formed on a glass plate by a dipping method, and dried at 200° C. for 20 minutes to form a frost film with a thickness of 3 μm.

Example 3 Fluororesin for solvent-soluble paint (non-volatile content 50%) 100
Parts by weight, butyl acetate 100 parts by weight, particle size 0.1-0.3
A coating agent was prepared by blending 30 parts by weight of precipitated barium sulfate with a particle diameter of 1.5 μm and dispersing it with a sand grinder for 45 minutes, followed by adding 10 parts by weight of methylated melamine as a hardening agent. This coating agent was applied to a glass plate by spin coating, and dried at 200° C. for 5 minutes to form a frost film with a thickness of 3 μm.

Example 4 Urethane acrylate ultraviolet curing resin (non-volatile content 80
%) 100 parts by weight, butyl acetate 200 parts by weight, particle size 0.
05 to 0.5 μm SiO2 4 parts by weight is blended,
Dispersion was performed using a sand grinder for 30 minutes. This coating agent was applied to a glass plate by spin coating to form a 1 μm frost film, and after drying at room temperature, the film was cured by irradiation with ultraviolet rays.

Example 5 100 parts by weight of silicone varnish (nonvolatile content 50%), 25 parts by weight of zinc oxide with a particle size of 0.05 to 0.5 μm, particle size 0
．． 25 parts by weight of precipitated barium sulfate with a particle diameter of 1 to 0.3 μm and 350 parts by weight of toluene were blended, and the mixture was ground with a sand grinder for 30 minutes.
After 0 minutes of dispersion, isocyanate 20 as a hardening agent.
A coating agent was prepared by adding parts by weight. This coating agent was spray-coated onto a glass plate and dried at 60° C. for 30 minutes to form a frost coating with a thickness of 4 μm. When the spectrum of this film was measured, it was found that ultraviolet rays were rapidly absorbed from 380 nm.

[0023]

[Effects of the Invention] By using the frosting coating composition of the present invention, glass can be frosted without corroding the glass surface, and waste liquid treatment is not necessary in this process. The total light transmittance of the glass having a frost film formed from the composition of the present invention is 60% or more,
The diffused transmittance can be arbitrarily controlled within the range of 5 to 90%.

Claims (2)

[Claims] [Claim 1] SiO2, Al2O3, BaS
O4, CaSO4, CaCO3, ZnO, ZrO
At least one kind of inorganic oxide selected from 2.
A frosted coating composition comprising a binder dispersed in a solvent. [Claim 2] The particle size of the inorganic oxide is 0.01 to 10μ.
The frosted coating composition according to claim 1, wherein the frosted coating composition is m.