JPH03199043A - Antireflection film and forming method thereof - Google Patents

Abstract

PURPOSE:To obtain antireflection film, which can reduce the reflection of light over wide wave range, by a method wherein solution containing specified monoalkyl trialkoxysilane, polyether and organic solvent is applied onto the surface of base so as to elute the polyether after the dehydration condensation of some part or all of the monoalkyl trialkoxysilane. CONSTITUTION:Solution containing monoalkyl trialkoxysilane represented by the formula (I), in which R is alkyl group having the number of carbon atoms of 1-4 and R' is alkyl group having the number of carbon of 1-6, polyether and organic solvent is applied onto the surface of base so as to form coated film through the dehydration condensation of some part or all of the monoalkyl trialkoxysilane and, after that, elute the polyether by means of organic solvent from the coated film in order to form antireflection film on the base. As the preferable alkoxy group of the monoalkyl trialkoxysilane, methoxy group, ethoxy group and propoxy group. The preferable polyether is polyethylene glycol having the degree of polymerization of 200-6,000. As the organic solvent, alcohols, ketones, esters or the like is used.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an anti-reflection film and a method for forming the same, and in particular to a single-layer anti-reflection film that can impart low reflectance to a substrate over a wide wavelength range and its method. Regarding the forming method.

[Conventional technology]

BACKGROUND ART Conventionally, a MgFz vapor-deposited film is known as a single-layer antireflection film coated on optical parts, eyeglasses, display devices, and the like. However, the single layer MgFz vapor-deposited film has the drawback that low reflectance cannot be obtained over a wide wavelength range. As a technology to solve the above drawbacks, magazine thin solid film (Thin 5solid film) has been developed.
Films) 129.1985) 1 discloses a method for producing a broadband antireflection film by coating a substrate with a SiOg thin film having pores by a sol-gel method using tetraethoxysilane as a raw material.

[Problem to be solved by the invention]

However, the method of coating a substrate with a SiOg film having pores using the above-mentioned sol-gel method requires a heating step and a step of imparting porosity with an HF aqueous solution after applying a hydrolysis product of tetraethoxysilane to the substrate. The process of forming the film is complicated. Furthermore, H is dangerous to the human body.
There is an environmental problem in that an F aqueous solution must be handled. The present invention provides a single-layer antireflection film that does not have the above-mentioned drawbacks and can reduce light reflection over a wide wavelength range, and a method for forming the same.

[Means to solve the problem]

In the present invention, a solution containing a monoalkyltrialkoxysilane whose general formula is represented by formula (1), a polyether, and an organic solvent is applied to the surface of a substrate, and part or all of the monoalkyltrialkoxysilane is dehydrated and condensed. In this method, the polyether is eluted from the coating film using an organic solvent to form a film having antireflection properties on the substrate. Monoalkyl trialkyl R-Si- (OR')3 (1) according to the present invention
(In the formula, R is an alkyl group having 1 to 4 carbon atoms, and R' is an alkyl group having 1 to 6 carbon atoms.) 804(C)Iz)O+ fiH(2) (in the formula,
(n is an integer) The alkyl group R of disilane is preferably a methyl group, an ethyl group, or a propyl group from the viewpoint of increasing the mechanical strength of the membrane, and particularly a methyl group is most preferable.

In addition, the number of carbon atoms in the alkyl group R' is related to the reaction rate of hydrolysis and dehydration condensation. The alkoxy group of the silane is preferably a methoxy group, an ethoxy group, or a propoxy group.

Furthermore, dialkyldialkoxysilanes such as dimethyljethoxysilane and dimethyldimethoxysilane, and ditrimethylmonoalkoxysilanes such as trimethylmonomethoxysilane and trimethylmonoethoxysilane can be added to the above-mentioned monoalkyltrialkoxysilanes.

The polyether according to the present invention is preferably polyethylene glycol, polypropylene glycol, or polytetramethylene glycol, which is represented by the general formula (2) and has k of 2 and 3.4, respectively, because they are well soluble in organic solvents. Particularly preferred is polyethylene glycol.

What is the value of n indicating the degree of polymerization of the polyether mentioned above?

200 to 6.000 is preferable, more preferably 300 to 2.0
00 is most preferred. If the degree of polymerization is less than 200, porosity will hardly occur in the film, making it impossible to lower the refractive index of the film. On the other hand, if the degree of polymerization exceeds 6,000, it becomes difficult to dissolve in organic solvents, making it difficult to prepare solutions.
This is not preferred because it becomes difficult to uniformly apply the solution to the surface of the substrate. If it is desired to increase the size of the large number of pores produced in the membrane, polyethers with a high degree of polymerization are selected. Further, the volume ratio occupied by pores in the membrane is adjusted by changing the ratio of monoalkyltrialkoxysilane to polyether.

The organic solvent according to the present invention is -valent or divalent.

Organic solvents such as trihydric alcohols, ketones, esters, ethers, cellosolves, halides, carboxylic acids, aromatic compounds, ethers, and ketone alcohols are used. Further, one kind or a mixture of two or more kinds thereof can also be used. In particular, lower alcohols such as methanol, ethanol, propatool, isopropanol, butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, lower alkyl carboxylic acids such as formic acid, acetic acid, propionic acid, toluene, xylene, ethyl acetate. , butyl acetate, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone are preferably used alone or as a mixed solvent in order to dissolve the polyether well.

In addition, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and organic acids such as acetic acid, Furthermore, water etc. can be added.

By applying the above solution to the surface of the substrate, part or all of the silane compound is dehydrated and condensed, and the solvent is evaporated and evaporated to form a gel-like coating film on the substrate. By bringing the obtained coating film mainly consisting of a dehydration condensation product of a silane compound and polyether into contact with the above-mentioned organic solvent, only the polyether is eluted into the organic solvent, and a film having pores is formed in the film. It is formed.

The present invention also provides a method for applying a solution containing a monoalkyltrialkoxysilane represented by the general formula (1) 2, a polyether, and an organic solvent to a substrate, and dehydrating part or all of the monoalkyltrialkoxysilane. This is a method of forming a film having antireflection properties on a substrate by forming a condensed coating film and heating the coating film. In order to almost completely decompose and remove the organic components in the coating film by heating, it is preferable to heat to 250°C or higher, preferably 300°C or higher. Among the polyethers mentioned above, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol are preferable because they hardly produce organic residues in the film through thermal decomposition, and polyethylene glycol is particularly preferable. Organic solvents include various alcohols, acids, ketones, aldehydes, ethers,
Ketone alcohols can be used.

The present invention also provides a porous membrane made of a product obtained by hydrolysis and dehydration condensation of part or all of a monoalkyltrialkoxysilane, the porosity of the membrane being expressed by the general formula (
This is a porous antireflection film obtained by dissolving the polyether with an organic solvent from a coating film in which the surface of a substrate is coated with a solution containing a monoalkyltrialkoxysilane represented by 1), a polyether, and an organic solvent. The organic solvent for dissolving the polyether from the coating film is not particularly limited as long as it is soluble in the above-mentioned alcohols, ketones, esters, cellosolves, aromatic compounds, and the like.

The present invention also provides a membrane made of porous silicon oxide obtained by thermally decomposing a product obtained by dehydrating and condensing a part or all of a monoalkyltrialkoxysilane, wherein This is a porous antireflection film produced from a coating film coated on the surface of a substrate containing a monoalkyltrialkoxysilane represented by the general formula (1), polyether, and an organic solvent.

Since the antireflection film of the present invention has many fine pores in the film, the refractive index of the film is small.

The porosity of the film is preferably 20 to 70% in order to ensure the mechanical strength of the film and to lower the reflectance. If the porosity is less than 20%, the refractive index of the film will be greater than 1.3, making it impossible to lower the reflectance of the substrate. If the volume occupied by pores exceeds 70%, the mechanical strength of the membrane becomes brittle, which is not preferable.

The reason why the antireflection film obtained by the present invention exhibits low reflection over a wide band is not clear, but the volume ratio of pores in the film increases continuously from the substrate surface side toward the atmosphere. This is thought to be due to the fact that the refractive index decreases from the substrate surface toward the atmosphere.

Substrates used in the present invention include glass plates, plastic plates, and the like. As the glass plate, a glass plate such as quartz glass, soda lime glass, or borosilicate glass can be used. As the plastic plate, a plastic plate such as PC polycarbonate or acrylic can be used.

[Function] The polyether contained in the coating film according to the present invention makes the film porous by being eluted with an organic solvent or thermally decomposed by heating.

The monoalkyltrialkoxysilane used in the present invention becomes a product of the antireflection film by dehydration condensation or by being heated and thermally decomposed.

The pores in the film lower the refractive index of the film, and since the volume ratio of the pores increases from the substrate toward the atmosphere, it imparts low reflectance to the substrate over a wide band.

〔Example〕

Example 1 17.83 g PP1 of monomethyltriethoxysilane was mixed with 13.82 g of ethanol and 22.24 g of 1-butanol to form a homogeneous solution.

To this solution, 10.8 g of water and 0.49 g of phosphoric acid were added, and the mixture was further stirred for 60 minutes. 13.82 in this solution
g of ethanol, 22.24 g of butanol and 3.
A coating solution was obtained by adding 3 g of polyethylene glycol and stirring for an additional 10 minutes.

A disk-shaped quartz glass plate with a thickness of 1.1 plates and a diameter of 50 mm was dipped into this coating solution, and then slowly pulled up.
A coating film was formed on a float glass plate. After that, the glass plate with this coating film was dried at room temperature for 5 minutes, and
Heat treatment was performed for 15 minutes in an oven maintained at 50'C.

By this heat treatment, the polyethylene glycol dispersed in the coating film was completely decomposed and burned, and the coating film became a transparent film with a thickness of 700 nm.

When the spectral reflection characteristics of the obtained sample were measured, it showed excellent antireflection characteristics with a spectral reflectance of 0.7% or less in the range of 350 to 850 nm, as shown by the solid line in FIG.

Example 2 A coating film was formed on a float glass plate in exactly the same manner as in Example 1. After drying at room temperature, the glass plate coated with this gel film was immersed in ethanol to remove polyether by elution from the coated film. When the spectral reflection characteristics of the sample obtained after drying at room temperature were measured, the spectral reflection characteristics shown by the dotted line in FIG. 1 were obtained.

It can be seen that the samples obtained in Example 1.2 all exhibit low reflectance over the entire visible range.

[Effects of the Invention] According to the present invention, an antireflection film having low reflectance over a wide wavelength range can be obtained in a single layer without having to have a multilayer structure. Therefore, a broadband antireflection film can be formed without requiring expensive equipment such as a vacuum evaporation device.

Furthermore, according to the method for forming an antireflection film of the present invention, an HF aqueous solution that is harmful to the human body is not used, so FIG. 1 is a diagram showing the characteristics of the antireflection film obtained by the method of the present invention. .

Procedural amendment dated March 20, 1990 1. Indication of the case Japanese Patent Application No. 1-342368 2. Name of the invention Anti-reflective film and its formation method 3. Person making the amendment Relationship to the case Patent applicant address Osaka City 3-5-11 Doshomachi, Chuo-ku Name
(400) Nippon Sheet Glass Co., Ltd. Representative Tatsuji Nakajima 4, Agent Address Shinbashi Sumitomo Building, 5-11-3 Shinbashi, Minato-ku, Tokyo Nippon Sheet Glass Co., Ltd. Patent Department 7 Contents of amendment (1) Specification page 6 Correct "ditrimethylmonoalkoxysilane" in lines 2 to 3 to "trialkylmonoalkoxysilane".

(2) "Adjustment" on page 6, line 15 of the specification is corrected to "preparation."

(3) "Accelerate" in the first line of page 8 of the specification is corrected to "promote."

6. Subject of correction

Claims (1)

[Claims] 1) A solution containing a monoalkyltrialkoxysilane whose general formula is represented by the formula (1), a polyether, and an organic solvent is applied to the surface of a substrate, and a part of the monoalkyltrialkoxysilane or A coating film is obtained by dehydrating and condensing the entire
Thereafter, the polyether is eluted from the coating film with an organic solvent to form a film having antireflection properties on the substrate R-Si-(OR')_3(1) ~4 alkyl group, R' is an alkyl group having 1 to 6 carbon atoms) 2) A solution containing a monoalkyltrialkoxysilane whose general formula is represented by formula (1), a polyether, and an organic solvent is applied to the surface of the substrate. a coating film in which a part or all of the monoalkyltrialkoxysilane is dehydrated and condensed;
A method of forming a film having antireflection properties on a substrate by heating the coating film R-Si-(OR')_3(1) (wherein R is an alkyl group having 1 to 4 carbon atoms, R' is an alkyl group having 1 to 6 carbon atoms) 3) A porous membrane, the porosity of the membrane is expressed by the general formula (1)
) The polyether is eluted from a coating film containing a dehydrated condensate of part or all of the monoalkyltrialkoxysilane, which is coated on the surface of a substrate with a solution containing the monoalkyltrialkoxysilane represented by the formula, polyether, and an organic solvent. Porous antireflection film R-Si-(OR')_3(1) (R is an alkyl group having 1 to 4 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and R' is an alkyl group having 1 to 4 carbon atoms.
-6 alkyl group) 4) A film made of porous silicon oxide, the porosity of the film being determined by a solution containing a monoalkyltrialkoxysilane represented by the general formula (1), a polyether, and an organic solvent. An antireflection film R- is formed by heating a coating film containing a dehydrated condensate of part or all of a monoalkyltrialkoxysilane coated on a substrate surface, and removing organic components in the coating film by thermal decomposition. Si-(OR')_3(1) (R is an alkyl group having 1 to 4 carbon atoms, R' is an alkyl group having 1 carbon number
~6 alkyl group)