JPH06279061A - Antifouling glass article having low reflectance - Google Patents

Abstract

PURPOSE:To obtain the subject glass article useful as CRT front glass of computers, etc., by forming an antireflecting film composed of a porous substance and an antifouling layer of a fluorosilane on the surface of a glass substrate. CONSTITUTION:A porous layer of this glass article is typically a skeletal layer prepared in treating the glass surface with an inorganic acid. This layer is obtained by immersing a silicate glass substrate in a supersaturated aqueous solution of silica in 1-4 mol hydrosilicofluoric acid per 1 at 25-50 deg.C for 1-4hr, eluting components other than silicon oxide in the surface layer of the substrate, e.g. components such as Na or K in the aqueous solution and removing the components from the surface layer. The thickness of the surface layer is preferably 10-300nm. A material for forming an antifouling layer may be a material having chemical binding properties to the porous surface and a low surface free energy. A fluorosilane-based material is preferred as an especially effective one and heptadecafluoromethyldichlorosilane, etc., are preferred. The antifouling layer is prepared by a vacuum CVD method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antifouling low reflectance glass, and more particularly to an antifouling low reflectance glass used for a display of a personal computer such as a front glass of a CRT.

[0002]

2. Description of the Related Art In recent years, with the rapid development of OA, eye fatigue caused by CRT work for a long time has become a problem. To alleviate this problem, antireflection glass is used on the front of the CRT. Methods for reducing the reflectance of glass include the use of (i) a low refractive index film, (ii) a multilayer interference film, and (iii) a porous film.

The reduction in reflectance due to the low refractive index film is based on the effect of light interference. Theoretically, the optical thickness of the coating is λ / 4 (λ is the wavelength), and the refractive index (n _f ) of the coating and the refractive index ( _ng ) of the glass at the wavelength λ are n _f = n _g ^1/2
In the relationship of, the reflectance of light at the wavelength λ becomes zero. Since n _g is about 1.5, the material with n _f = 1.22 is optimal. Actually, MgF ₂ (n _f = 1.38) or cryolite (AlF ₃ ) having a refractive index close to this is used.
· 3NaF, n _f = 1.33) is used.

The multi-layer interference film is formed by alternately stacking high-refractive index films and low-refractive index films based on the theory of multi-layer interference of light, and can reduce the reflectance in a wider wavelength range than a single-layer film. It is possible. In terms of material, it is usually M as a low refractive index film.
gF ₂ , SiO ₂ (n _f = 1.46) is used as the high refractive index film TiO ₂ (n _f = 2.3).

A typical example of the porous layer is a skeleton layer obtained by treating the glass surface with an inorganic acid. This skeleton layer is formed by immersing a silicate glass substrate in a silica supersaturated aqueous solution of hydrosilicofluoric acid at a concentration of 1 to 4 mol per liter at 25 to 50 ° C. for 1 to 4 hours in the surface layer of the substrate. It is formed by eluting components other than silicon oxide, such as sodium and potassium, in an aqueous solution and removing them from the surface layer.

The diameter of each skeleton of the skeleton layer thus obtained is several nm to several tens nm. Further, the thickness of the skeleton layer increases as the contact time between the base material and the silica supersaturated aqueous solution of hydrofluoric acid increases, but
0 nm to 300 nm is suitable. When it exceeds 300 nm, the transparency of the glass article is lowered, which is not preferable.

[0007]

Comparing the antireflection performances of the three parties, the multilayer interference film and the porous layer are generally particularly excellent.

However, the multilayer interference film is not only difficult to control the film thickness, but also high in cost. This is an unavoidable problem because it is a multilayer film.

On the other hand, since the porous layer can be processed by one layer, it is advantageous in terms of cost, but it is easy to get stains due to the uneven surface, and for example, when a human finger touches the front glass plate It has a drawback that the oil and fat component is easily attached to the glass surface and is hard to be removed. In addition, the problem is that the surface is easily scratched if the dirt is forcibly removed.

[0010]

SUMMARY OF THE INVENTION In order to overcome the problems of stains generally associated with a low reflection glass having a porous layer as described above, the low reflection glass article according to the present invention comprises fluorosilane on the outermost surface. The antifouling layer is provided.

As a material for forming the antifouling layer, any material can be used as long as it has a low surface free energy and has a chemical bond with the surface of the porous layer. Ordinary silane coupling agents, polyorganosiloxanes, etc. have some effect and can be used, but as a result of earnest research by the inventors,
It has been found that fluorosilane-based materials are particularly effective. As the fluorosilane-based material, it is possible to use fluorosilane having at least one chlorine at one end, and the like, but heptadecafluoromethyldichlorosilane, heptadecafluorotrichlorosilane and the like can be particularly preferably used. .

The method for depositing the antifouling layer is not particularly limited, and a known rubbing method, dipping method, sol-gel method or the like can be used, but from the viewpoint of forming a uniform film inside the porous material. It became clear that the low pressure CVD method is particularly effective.

The degree of vacuum during the CVD process may be set so that a sufficient vapor pressure of the fluorosilane-based material can be obtained. Therefore, about 10 Torr is usually sufficient, although it depends on the type of fluorosilane-based material used.

In order to promote the reaction between the antifouling layer and the surface of the substrate, it is effective to heat the substrate during the CVD process. The heating temperature varies depending on the substrate surface material and the type of treatment agent, but the SiO ₂ surface should be at least 1 at one end.
In the case of treating with a fluorosilane-based treating agent having chlorine, about 80 ° C. is sufficient. This reaction is a dehydrochlorination reaction of fluorosilane having Si-OH groups and chlorine groups.

The antifouling layer is preferably a monomolecular film.

[0016]

EXAMPLES The antifouling low reflection glass according to the example of the present invention shown in FIG. 1 will be described in detail below. FIG. 1 schematically shows a cross section of a substrate obtained by applying antifouling treatment to soda lime glass having a porous antireflection film formed on the surface thereof. 1
Is a glass substrate, 2 is a porous low reflectance film, and 3 is an antifouling layer. The shape of the matchstick that constitutes the antifouling layer 3 represents a perfluoro group molecule, and the head portion of the matchstick is a siloxane-bonded molecule with the base material and enters the pores of the porous low reflectance film.

A soda lime glass plate was immersed in a 1.0% aqueous solution of hydrofluoric acid for 30 minutes to remove surface stains, and then washed with water. Next, at 35 ° C., the silica gel powder is dissolved in hydrosilicofluoric acid at a concentration of 2.0 mol per liter until saturation is reached, that is, 20 g per liter is added, and further boric acid is added at 0.005 mol per liter. Then, a silica supersaturated aqueous solution was prepared. The glass substrate is immersed in this aqueous solution for 100 minutes to have a thickness of about 90 nm on the surface of the glass plate.
The skeleton layer of Then it was washed and dried.

A petri dish containing about 0.2 g of hexadecafluorodecyltrichlorosilane (HDFDTCS) and the antireflection glass substrate were set in the chamber. After evacuation with a vacuum pump for 2 minutes, the system was closed and heated to 80 ° C. After reacting for 1 hour, the temperature was raised to 99 ° C while vacuuming, and excess H
DFDTCS was removed. As a result, an antifouling low-reflectance glass consisting of a glass substrate, a 900-nm-thick porous glass antireflection film coating on the surface thereof, and a fluorosilane monomolecular film thereon was obtained as shown in FIG. In addition, in order to investigate reproducibility, the same experiment was repeated and two samples were prepared.

FIG. 2 is a visible light reflectance spectrum. In normal untreated soda lime glass 1 (dashed line),
The glass plate 2 (dotted line) has a reflectance of 8 to 9%, whereas a porous layer is not formed on the surface and only an antifouling layer is formed.
Has a significantly reduced reflectance (0.21 at a wavelength of 500 nm).
%). Further, it is clear that the antifouling low reflectance glass 3 (solid line) in which an antifouling layer is further formed on the porous layer maintains the reflectance reducing effect sufficiently (0 at a wavelength of 500 nm. .72%).

Next, the same person lightly touched the surface of the glass plate sample having the porous layer formed on the surface and the antifouling low reflectance glass plate sample having the antifouling layer formed on the porous layer with a finger. When touching and observing the left and right fingerprints on the glass at the same time, the fingerprint traces are clearly visible in the former sample, whereas the fingerprint traces are faint in the latter sample and stains due to the presence or absence of antifouling treatment. The difference was clear. From this, it can be seen that fingerprints are less likely to be attached by applying the antifouling treatment.

Water (surface tension: 72.8 mNm ^-1 ) and n-hexadecane (surface tension: 27.3 mNm ^-1 ) for the low-reflection glass before the antifouling treatment and the low-reflectance glass for which the antifouling treatment has been performed. When the contact angle of was measured,
The low-reflection glass before the antifouling treatment has a contact angle of water of 0 degree and that of n-hexadecane is 0 degrees, while the water and n of the low-reflection glass subjected to the antifouling treatment have a contact angle of 0 degree. -The contact angle of hexadecane is 120.9 each.
Degrees (standard deviation 1.17) and 80.7 degrees (standard deviation 3.46). It can be seen that in all cases, the contact angle of the sample subjected to the antifouling treatment is significantly larger. From this result, it is clear that the antifouling treatment makes it difficult for water, oil, etc. to adhere. Therefore, it can be understood that the antifouling effect is exhibited against hydrophilic and lipophilic stains.

[0022]

As described above, the antifouling low-reflectance glass of the present invention has a large antireflection function and, at the same time, has an excellent antifouling function because stains such as fingerprints are not easily attached. it is obvious.

Therefore, the antifouling low reflectance glass according to the present invention can be suitably used for a CRT front glass of a computer or the like.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a constitution of an antifouling low reflection glass of the present invention.

FIG. 2 is an explanatory diagram showing a visible light reflection spectrum of the antifouling low reflection glass of the present invention.

[Explanation of symbols]

 1 Glass Substrate 2 Antireflection (Porous) Film 3 Antifouling Layer

Claims (2)

[Claims] 1. A glass substrate (1), a porous antireflection film (2) formed on the surface of the glass substrate (1), and an antireflection film (2) formed on the surface of the antireflection film (2). An antifouling low reflectance glass comprising a fluorosilane antifouling layer (3). 2. The antifouling low-reflectance glass article according to claim 1, wherein the antifouling layer is (3) produced by a low pressure CVD method.