JPH1111983A - Manufacturing method of water-repellent glass coat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the heat resistance is low because the fluorine molecules in the conventional water repellent glass having the same hardness as the glass and the water repellency comparable to the fluororesin are not covalently bonded to the glass. there were. SOLUTION: After a glass coating solution is applied to a solid substrate, the substrate is exposed to an alkaline solution and then subjected to a heat treatment to promote the covalent bond between the fluorocarbon chain and the glass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a water-repellent glass having both the water repellency of a fluororesin and the hardness of a glass. In particular, an object of the present invention is to provide a method for producing a water-repellent glass coat film having excellent heat resistance.

[0002]

2. Description of the Related Art A water-repellent glass coat is described in "Tokyo Metropolitan Industrial Technology Center Research Report No. 22, 1993".
Year "," Japanese Patent Application Laid-Open No. 4-338137 ", and" Ceramics, Vol. 29, No. 6, page 533, 1994 "report the technical contents. In the following, the production of the above-mentioned conventional water-repellent glass coat is described. The method will be described with reference to the drawings.

A first example will be described with reference to FIG. First, two solutions are made. The two solutions are tetraethoxysilane (Si (O2CH5) 4: TEOS
) And perfluoroalkylmethoxysilane (CF3 (CF2) 7C2H4Si (OCH3) 3) in ethanol (hereinafter referred to as A solution), and an ethanol solution in which water and hydrochloric acid are dissolved (hereinafter referred to as solution B). That is.

Here, the above-mentioned solution A is a solution that becomes the main body of the water-repellent glass coat, and is basically made of fluorine (this fluorine is the basis for giving the water-repellent property) and the raw material of the glass. It is contained.

[0005] The above solution B is a solution for converting the above solution A into a coating solution for water-repellent glass coating and silanolization.

Next, the above-mentioned solution A and solution B are mixed to cause the above-mentioned hydrolysis reaction of TEOS and perfluoroalkylmethoxysilane, in other words, silanolation (formula 1), thereby forming a water-repellent glass coat film. Make a coating solution for

[0007]

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Further, the coating solution formed as described above is applied on glass as a substrate.

Finally, the substrate on which the coating solution is formed is
Baking at 00 ° C. to form a water-repellent glass coat film.
In this firing step, two types of reactions proceed.

The first is a reaction for removing unnecessary water and ethanol contained in the coating solution formed on the substrate, and the second is a silanol conversion as shown in the following chemical formula (2). This is a reaction for dehydrating TEOS and perfluoroalkylmethoxysilane.

[0011]

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The method of making the water-repellent glass coat according to the second example is basically the same as the method in the first example. That is, an aqueous solution of hydrochloric acid is dropped into an ethanol solution in which TEOS and perfluoroalkylmethoxysilane (CF3 (CF2) 7C2H4Si (OCH3) 3) are dissolved to form a coating solution, which is then applied to a solid substrate and fired. This describes that a water-repellent glass coat can be prepared.

A third example will be described with reference to FIG. First, water and a hydrochloric acid catalyst are added to an ethanol solution of TEOS, and then polyethylene glycol is added thereto to prepare a glass forming solution.

Next, the glass forming solution formed in the above step is coated on glass as a substrate. Then, the substrate on which the glass forming solution is formed is placed in a range of 250 to 35.
At the same time as firing at 0 ° C. to polymerize the tetraethoxysilane, polyerylene glycol is burned to form a porous silica glass on the glass.

Next, after diluting the fluoroalkyltrimethoxysilane with methanol, water is added to the solution, and a partially hydrolyzed coating solution is applied to the above glass, and then baked at 400 to 600 ° C. A water-repellent film is formed on the porous silica glass described above, and as a result, a water-repellent glass coat is produced.

[0016]

The water-repellent glass coats shown in the first and second examples are prepared by preparing a glass coat solution containing a fluorine component having water repellency in advance, and then preparing the glass coat solution. Is applied and baked to form a water-repellent glass coat.

[0017] For this reason, not only the surface of the formed glass coat but also the inside thereof contains fluorine, so that even if the surface is worn by some influence, fluorine remains and water repellency can be maintained. It is a coat excellent in abrasion resistance and a coat film excellent in heat resistance as compared with a fluororesin.

However, this water-repellent coat is 30
When exposed to an atmosphere of 0 ° C. or higher, there is a problem that the water repellency gradually disappears. Generally, the contact angle with water is 8
It is said that the water repellency decreases significantly when the temperature is 0 ° or less. However, in the water repellent coat formed by the above-mentioned first conventional method, for example, the water repellency coat at 300 ° C. for about 100 hours is used. The contact angle is less than 80 degrees.

In the water-repellent glass coat shown in the third reference, since fluorine molecules are contained only in porous pores, a water-repellent coat having a surface with irregularities is formed. Although there is an advantage that the surface area can be increased, the manufacturing process requires two firings, and the number of processes is complicated, which is inferior to the first conventional example. In addition, since fluorine molecules exist only on the surface of glass and are not uniformly contained in glass molecules, they are produced by the first conventional method in which fluorine molecules are uniformly contained in glass. There is also a problem that the abrasion resistance is inferior to water-repellent glass.

The present invention has been made to solve the above-mentioned problems, and has a water repellency comparable to that of a fluororesin coating, excellent abrasion resistance, and a durable water repellency which is maintained even in an atmosphere of 300 ° C. or more. Highly water-repellent glass coat,
And a method for producing the same.

[0021]

The inventor of the present invention has found that the above-mentioned conventional water-repellent coat has poor durability at a temperature of 300 ° C. or more because of the water-repellent glass coats of the first and second references. It was found that the covalent bond between the fluorine compound and the glass was insufficient, and by solving this problem, the water repellency was as high as that of the fluorine coat, the abrasion resistance was excellent, and the water repellency was further improved.
It has been considered that it is possible to provide a water-repellent glass coat that maintains water repellency even in an atmosphere at a temperature of not less than ° C.

As a specific means, the method for producing a water-repellent glass coat of the present invention is a precursor of a fluorocarbon compound containing a methoxysilyl group or an ethoxysilyl group and a glass mainly containing silicon oxide. Hydrolyzing a mixed solution of a methoxysilane or ethoxysilane compound in the presence of an acidic catalyst and water, and subjecting the mixture to dehydration polymerization, and then applying the mixed solution to a solid substrate; and A step of hydrolyzing the non-hydrolyzed fluorocarbon compound or the precursor compound of the glass by exposing the substrate surface to an alkaline solution and performing dehydration polymerization,
Next, the method comprises a step of drying the base material, and finally, a step of subjecting the base material to a heat treatment to dehydrate and polymerize the hydrolyzed fluorocarbon compound or the glass precursor compound.

Further, in the present manufacturing method, when exposing the base material to the alkaline solution, it is preferable that the base material is immersed in the alkaline solution.

In the present manufacturing method, when exposing the base material to the alkaline solution, it is preferable that the base material is exposed to the vapor of the alkaline solution.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A water-repellent glass coat according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a manufacturing process diagram of a water-repellent glass coat according to an embodiment of the present invention. As shown in FIG. 1, an ethanol solution (hereinafter referred to as A solution) in which perfluoroalkylmethoxysilane (CF3 (CF2) 7C2H4Si (OCH3) 3) and tetraethoxysilane (Si (OCH3) 4: hereinafter abbreviated as TEOS) are dissolved. ) And an ethanol solution in which water and hydrochloric acid are dissolved (hereinafter referred to as B
2) are prepared.

Next, the solution B is added to the solution A, and the perfluoroalkylmethoxysilane in the solution A and T
EOS is hydrolyzed (a reaction similar to the above (Chemical Formula 1)),
Silanolates perfluoroalkylmethoxysilane and TEOS.

Next, the coating solution formed as described above is applied to glass as a substrate.

Further, the glass is taken out after being immersed in an aqueous ammonia solution, or exposed to the vapor of ammonia, dried at room temperature, and baked to form a water-repellent glass coat. In addition, this baking step removes unnecessary water and ethanol contained in the coating solution formed on the substrate, as in the above-described conventional case,
The silanolated TEOS and the perfluoroalkylmethoxysilane are subjected to a dehydration reaction.

The most important feature of the present invention is that after the coating liquid is applied to the substrate, the applied coat is exposed to an alkaline solution. The conventional method of producing a water-repellent glass coat merely involves baking after applying a coating liquid. The reason why the coat prepared by the method of the present invention has improved heat resistance as compared with the coat prepared by the conventional method will be described below.

In the presence of an acid catalyst, as shown in (Chem. 3), generally, when one of a methoxy group or an ethoxy group (hereinafter referred to as an alkoxide) present in one molecule is substituted with a hydroxyl group, The reaction rate at which the second alkoxide is substituted with a hydroxyl group is extremely reduced.

[0032]

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For this reason, a molecule in which only part of the alkoxide in the molecule has been substituted with a hydroxyl group undergoes dehydration polymerization. As a result, as shown in FIG. 7, the water-repellent glass coat is composed of molecules in which alkoxide remains.

Ideally, fluoroalkyltriethoxysilane should be linked to neighboring molecules by 3 covalent bonds and TEOS to 4 covalent bonds. However, the number of covalent bonds in a water-repellent glass prepared by a conventional method should be considered. Is far less than the number of covalent bonds in the ideal state. Therefore, when the temperature reaches 300 ° C. or higher, molecules that are not covalently bonded or molecules that are covalently bonded to an adjacent molecule only at one position in the molecule are scattered to the outside of the coat. Is considered to decrease. This is the reason that the water-repellent glass coat formed by the conventional method has low heat resistance.

On the other hand, in the presence of an alkali catalyst,
It is considered that the rate of substitution of the alkoxide in the molecule with a hydroxyl group is very slow as compared with the rate in the case of an acid catalyst.
However, once the alkoxide is replaced with a hydroxyl group, the second and subsequent alkoxides are immediately replaced with a hydroxyl group, and finally, all alkoxides bonded to silicon are replaced with a hydroxyl group.

[0036]

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However, a solution of a molecule containing an alkoxide immediately becomes cloudy in the presence of an alkali catalyst, and cannot be used as a coating solution for a water-repellent glass coat. This is presumed to be because the silanolated molecules cause a polymerization reaction with each other to form an insoluble polymer. On the other hand, under an acidic catalyst, a solution containing an alkoxide maintains transparency even when left for several days, and can be used as a coating solution for a water-repellent glass coat.

In the present invention, first, a coating solution hydrolyzed under an acidic catalyst, which is easy to use as a coating solution, is applied to a solid substrate. The structure of the applied coating film is shown in FIG.
As shown in (a), it contains unreacted alkoxide.

Second, the unreacted alkoxide is replaced with a hydroxyl group by exposing the coat on the substrate to an alkaline solution. This substitution reaction proceeds immediately. This is because at least one alkoxide of the molecule in the coat has already been substituted with a hydroxyl group under an acidic catalyst, and the substitution of a second or subsequent alkoxide with a hydroxyl group occurs immediately under an alkaline catalyst. FIG. 2B shows the structure of the coat after being exposed to the alkaline solution.

Finally, by firing the substrate, the molecules in the coat undergo a dehydration polymerization reaction, and the molecules are covalently bonded to each other. As a result, a water-repellent glass coat having high heat resistance is formed. FIG. 2C shows the structure of the water-repellent glass coat after firing.

Next, specific examples of the above-described water-repellent glass coat of the present invention will be described.

Example 1 The following three solutions were prepared in advance to prepare a water-repellent glass coat on alkali glass.

Solution A 40 g ethanol 40 g TEOS 37 g CF 3 (CF 2) 7 C 2 H 4 Si (OCH 3) 3 10 g Solution B Ethanol 40 g Water 10 g Hydrochloric acid 1 g First, solution B was added dropwise while stirring solution A with a stirrer and stirred for 60 minutes. Next, a glass plate of 5 cm × 5 cm × 2 mm was vertically immersed in the solution so that the surface of 5 cm × 5 cm was perpendicular to the solution, and then about 0.15 mm / s
Raised at the speed. Next, the substrate was immersed in a 1 vol.% Aqueous ammonia solution for 10 minutes, taken out of the solution, and dried at room temperature for 1 hour. After heating at 100 ° C. for 10 minutes, baking was performed at 300 ° C. for 30 minutes to form a water-repellent glass coat on a glass plate.

Here, in order to clarify the characteristics of the water-repellent glass coat of the present invention, a water-repellent glass coat which was fired without being immersed in an ammonia solution after coating on a substrate was produced.

The water-repellent glass coat of the present invention and the glass coat as a comparative example, which were formed as described above, were used.
FIG. 3 shows the results of the heat resistance test at 0 ° C. This is a result of measuring the water repellency of the solid substrate at room temperature after leaving the solid substrate coated with the water-repellent glass in a 300 ° C. atmosphere for a certain period of time. The water repellency is evaluated by the static contact angle of pure water on the substrate. Generally, when the contact angle with water is less than 80 degrees, the water repellency is insufficient.

As is apparent from the results, the water-repellent glass coat prepared by the conventional method (first comparative experiment) loses water repellency in about 50 hours. Maintains its water repellency even after 50 hours.

(Embodiment 2) Next, an embodiment in which a water-repellent component is different from the water-repellent glass coat in the above-described embodiment 1 will be described.

The following three solutions were prepared in advance to prepare a water-repellent glass coat on alkali glass.

Solution A 40 g ethanol 40 g TEOS 37 g CF 3 (CF 2) 7 C 2 H 4 Si (OCH 3) 3 10 g Solution B Ethanol 40 g Water 10 g Hydrochloric acid 1 g First, solution B was added dropwise while stirring solution A with a stirrer and stirred for 60 minutes. Next, a glass plate of 5 cm × 5 cm × 2 mm was vertically immersed in the solution so that the surface of 5 cm × 5 cm was perpendicular to the solution, and then about 0.15 mm / s
Raised at the speed. Next, as shown in FIG. 4, this substrate was placed on a 1 vol.% Aqueous ammonia solution heated to 60 ° C. by a heater for 10 minutes. Then, it dried at room temperature for 1 hour. After further heating at 100 ° C. for 10 minutes, 350
It baked at 30 degreeC for 30 minutes, and produced the water-repellent glass coat on the glass plate.

The heat resistance of the water-repellent glass coat film of the present invention formed as described above was examined in the same manner as in Example 1. The result is shown in FIG. As is evident from the results in the figure, the water-repellent glass coat of the present invention has a
It can be seen that the water repellency is maintained even after the heat test for 0 hour.

In the embodiment of the present invention, CF3 (CF2) 7C2H4Si is used as a molecule containing a fluorocarbon chain.
(OCH3) 3 and (SiOCH3) 3 (CH2) 2 (CF2) 8
Although (CH2) 2Si (OCH3) was used, the present invention is not limited to this. Needless to say, it is also possible to use a fluorocarbon chain having 9 or more C atoms or 7 or less. . Further, in this example, a triethoxysilane compound was used. However, the present invention is not limited to this. Needless to say, dimethoxysilane, monomethoxysilane, or diethoxysilane or monoethoxysilane may be used. .

[0052]

The water-repellent glass used in the present invention is transparent, has the same hardness and abrasion resistance as glass, and has the same water repellency as a fluororesin, so that it can be used as a substitute for the fluororesin.

In the method for producing a water-repellent glass coat according to the present invention, the molecule having a fluorocarbon chain is composed of glass and Si—
Since it is O-bonded, a water-repellent glass coat film with high heat resistance can be obtained even if the proportion of molecules containing a fluorocarbon chain in the solution to be coated on the base material is lower than that of the conventional method. Cost reduction during fabrication is possible.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a water-repellent glass coat of the present invention.

FIG. 2 is a view showing a process of forming a water-repellent glass coat according to the present invention. (A) Schematic diagram of the structure of a water-repellent glass coat immediately after a coating liquid is applied to a solid substrate. (B) Exposure of the solid substrate to an alkali solution. Schematic diagram of the structure of the water-repellent glass coat after firing (c) Schematic diagram of the structure of the water-repellent glass coat after firing

FIG. 3 is a diagram showing the results of a heat resistance test at 300 ° C. of a water-repellent glass coat produced by the present invention and a conventional method.

FIG. 4 is a diagram showing a method of exposing a solid substrate to vapor of an alkaline solution.

FIG. 5 is a manufacturing process diagram of a conventional water-repellent glass coat.

FIG. 6 is a view showing a manufacturing process of a conventional water-repellent glass coat.

FIG. 7 is a schematic view of the structure of a conventional water-repellent glass coat.

[Explanation of symbols]

1 Solid substrate 2 Schematic diagram of the structure of the water-repellent glass coat after application of the coating liquid in the method 3 Schematic diagram of the structure of the water-repellent glass coat after exposure to an alkali solution 4 Method of the present invention Schematic diagram of water-repellent glass coat after firing 10 1 vol.% Aqueous ammonia solution 11 Container 12 Heater 20 Schematic diagram of structure of water-repellent glass coat produced by conventional method

Claims (3)

[Claims] 1. A mixed solution of a fluorocarbon compound containing a methoxysilyl group or an ethoxysilyl group and a methoxysilane or ethoxysilane compound that is a precursor of glass containing silicon oxide as a main component, is mixed with an acidic catalyst and water. A step of performing hydrolysis and dehydration polymerization in the presence of, a step of applying the mixed solution to a solid substrate, and exposing the surface of the solid substrate to an alkaline solution,
A step of hydrolyzing the unhydrolyzed fluorocarbon compound or the precursor compound of the glass to cause dehydration polymerization, a step of drying the base material, and a step of heat-treating the base material to form the hydrolyzed fluorine. Dehydrating and polymerizing a carbonized compound or a precursor compound of the glass. 2. The method for producing a water-repellent glass coat according to claim 1, wherein when exposing the substrate to the alkaline solution, the substrate is immersed in the alkaline solution. 3. The method for producing a water-repellent glass coat according to claim 1, wherein, when exposing the substrate to the alkaline solution, exposing the substrate to the vapor of the alkaline solution.