JPH0769680A - Water repellency treatment for inorganic substrate - Google Patents

Abstract

PURPOSE:To easily form a film having excellent water repellency for a long time even for a substrate having a mirror surface such as glass by subjecting an inorg. substrate to surface treatment with an acid soln., then applying a soln. of specified organosilazane polymer on the treated surface, and curing. CONSTITUTION:An inorg. substrate is immersed for surface treatment in an acid soln. of pH<=3.0 except for hydrofluoric acid. Then a soln. of organosilazane polymer expressed by formula is applied on the treated surface and cured to form a water-repellent film. In formula, R<1> and R<2> may be the same or different and are hydrogen atoms or (substd.) univalent hydrocarbon groups having 1-20 carbon number, R<3> is a hydrogen atom or alkyl group, Rf is a perfluoroalkyl group having 1-20 carbon number or perfluoroalkylether group having 2-35 carbon number, Q is a bivalent org. group having 2-5 carbon number, a is an integer 1-3, b is an integer 0-2, a+b is 1 to 3, c is an integer 0-2, d is an integer 1-3, c+d is 1 to 3, and m and n are integers >=1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water repellent treatment method for an inorganic non-porous substrate such as glass.

[0002]

As a method for imparting water repellency to the surface of glass, ceramics, various metals, etc., a method of treating the surface with an organopolysiloxane solution in the presence of an inorganic acid or an organic acid as a catalyst (special JP-A-50-15473, JP-A-63-67828 and JP-A-1-67393) are known. Further, a release agent composition containing an organosilazane polymer as a main component is known (JP-A-60-145815 and JP-A-60-221470), and by using these, water repellency can be relatively easily imparted to the surface. Can be granted. The applicant of the present invention has previously proposed a method of surface-treating a substrate using a fluorine-containing silazane compound (JP-A-3-290437, JP-A-4-258669).

[0003]

According to the above-mentioned various methods, it is possible to impart excellent water repellency to the surface of a substrate, but the water repellency coating does not have sufficient abrasion resistance and durability. Therefore, the sustainability of the effect was not sufficient. This tendency is particularly remarkable in a base material having a mirror surface (non-porous surface) such as glass. In such a base material, for example, even if a water-repellent film is formed by any method, it is about 3 or less. It has been pointed out that the water repellency is halved by outdoor exposure on the moon.

As a method for solving such a problem, JP-A-2-311332 discloses a method of coating a glass surface with a metal oxide layer and then silylating the surface with a silyl compound. Proposed. However, although this method improves the durability of the water-repellent coating for indoor use, it cannot sufficiently improve the durability for outdoor use, and requires high-temperature heating for forming the metal oxide layer. Because of the necessity, this method has a problem that it cannot be applied to tempered glass and the cost is very high.

Further, in Japanese Unexamined Patent Publication (Kokai) No. 5-97478, a silicate glass is immersed in a silica supersaturated aqueous solution of hydrosilicofluoric acid for a predetermined time to modify the surface of a base material into a porous layer, and an organic silicon compound is formed on the surface. And / or a method for producing a water-repellent glass by coating with an organic fluorine compound has been proposed. This method applies 100 to 3 to the glass surface which is the base material.
By forming a porous layer having a thickness of 000Å, the adhesiveness with an organic silicon compound or an organic fluorine compound forming a water-repellent coating layer is enhanced, and the durability of the coating layer is enhanced. However, this method
Since hydrosilicofluoric acid is used as a treatment agent for forming a porous layer on the glass surface, erosion of the glass surface becomes significant unless the process control during the treatment is strictly performed, resulting in interference. There is a problem that the appearance is impaired due to color development.

Therefore, an object of the present invention is to provide a water-repellent film which retains excellent water repellency for a long period of time even on a substrate having a mirror surface (non-porous surface) such as glass without impairing its appearance. Another object of the present invention is to provide a processing method which can be formed by an easy means.

[0007]

According to the present invention, an inorganic substrate is subjected to a surface treatment by immersing it in an acidic aqueous solution having a pH of 3.0 or less excluding hydrofluoric acid. General formula (1):

[Chemical 2] In the formula, R ¹ and R ² may be the same or different,
A hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R ³ is a hydrogen atom or an alkyl group, and R f is a perfluoroalkyl group having 1 to 20 carbon atoms. Alternatively, it is a perfluoroalkyl ether group having 2 to 35 carbon atoms, Q is a divalent organic group having 2 to 5 carbon atoms, a is an integer of 1 to 3, and b is 0 to 0. Is an integer of 2 and a + b is 1 to 3
And c is an integer of 0 to 2, and d is 1
Is an integer of 3 and c + d is 1 to 3, and m and n are integers of 1 or more, respectively. A solution of the organosilazane polymer represented by There is provided a method for treating water repellency of an inorganic substrate, which comprises forming a film.

[0008]

In the present invention, the pH excluding hydrofluoric acid is adjusted to 3.0 before the water-repellent film is formed by applying the specific organosilazane polymer solution represented by the general formula (1).
A remarkable feature is that the substrate is surface-treated by immersing it in the following acidic aqueous solution. By performing such a surface treatment, a film having water repellency that lasts for a long time is formed. More preferably, the pH is 2.0 or less.

That is, in the case of a water-repellent film formed by a conventional method, the film is removed from the surface of the substrate, the surface of the film is deteriorated due to abrasion, and the film is eroded due to the elution of an alkaline component from the substrate. In addition, it is considered that the water repellency does not continuously develop. On the other hand, according to the treatment method of the present invention, by treatment of the substrate surface with the acid aqueous solution,
The alkaline component on the surface of the base material is removed, and the erosion of the film due to the elution of the alkaline component is effectively avoided. Further, when a hydroxyl group is formed on the surface of the base material by the same treatment, the adhesion between the specific organosilazane polymer and the hydroxyl group improves the adhesion of the formed film to the base material. Furthermore, by roughening the surface of the base material with an acid aqueous solution, fine unevenness is formed on the surface of the base material, although to a different degree
As a result, the adhesion between the film to be formed later and the surface of the base material is improved, and the film is effectively prevented from coming off and deterioration due to abrasion, thus maintaining excellent water repellency for a long period of time. Presumed. In this case, when hydrofluoric acid is used, the characteristics such as the surface of the base material, the appearance and the like are remarkably impaired because the base material such as glass is highly corroded.

In the present invention, the organosilazane polymer represented by the general formula (1) has the following general formula (2):

(Rf Q) _a Si (R ¹ ) _b X _4-ab (2) In the formula, R ¹ , Rf, Q, a and b are as described above,
X is a halogen atom, and an organosilane represented by the following general composition formula (3):

(Rf Q) _c Si (R ² ) _d X _e O _{(4-cde) / 2} (3) In the formula, R ² , Rf, Q, c, d and X are as described above, and e Is represented by the following general formula (4): R ³ NH ₂ (4) where R ³ is as described above. Obtained by reacting with at least one selected from ammonia and primary amines.

The following may be mentioned as specific examples of the organosilane represented by the above general formula (2).

[0014]

[Chemical 3]

As the organopolysiloxane represented by the general composition formula (3), c + d in the formula (3) is 1.8 to 2.2 in terms of the surface characteristics of the obtained fluorine-containing silazane.
Is preferable, and from the viewpoint of the curing rate, it is preferable that e is in the range of 0.01 to 0.5. The halogen atom X is preferably chloride, bromine or the like. As a specific example of such an organopolysiloxane represented by the general composition formula (3), one represented by the following general formula (5) is preferable.

[0016]

[Chemical 4]

In the above formula, R ² , Rf and Q are as described above, and k + 1 is an integer of 8 or more, preferably 8 to 200.

The reaction between the organosilane represented by the general formula (2) and the organopolysiloxane represented by the general composition formula (3) is carried out by dissolving them in a suitable organic solvent and adding the above-mentioned general formula ( Ammonia represented by 4) or the first
The reaction may be carried out with at least one kind of amine. In this case, ammonia is particularly preferable, but methylamine,
Primary amines such as ethylamine, propylamine, butylamine, hexylamine and the like can also be suitably used. The organic solvent used in the reaction,
It is preferable to use one that is inert to ammonia gas and primary amines and that dissolves the resulting fluorine-containing silazane polymer well. Examples of such organic solvents include trichlorotrifluoroethane, meta (para) xylene hexafluoride, and benzotrifluoride. Although this reaction is an exothermic reaction, it is usually carried out at 0 to 50 ° C. while controlling the reaction temperature.

The amount ratio of the organosilane represented by the general formula (2) and the organopolysiloxane represented by the general composition formula (3) to be used in the reaction is such that the fluorine-containing silazane polymer obtained by the reaction has a ratio. 5 to 50 mol% siloxane units
It is preferable that the range is in the range of the curing rate of the obtained compound, the adhesiveness of the cured film obtained by curing to the substrate, the surface characteristics, and the like.

[0020]

DESCRIPTION OF PREFERRED EMBODIMENTS Inorganic Substrate In the present invention, as the inorganic substrate to be surface-treated, a substrate made of glass, ceramics, various metals or the like can be used, but particularly preferably, glass is used. A base material having a mirror surface such as is used.

[0021] As the acid solution used in the surface treatment by the surface treatment immersion, pH excluding hydrofluoric acid is used those of 3.0 or less. pH is 3.
When the value higher than 0 is used, the effect of removing the alkaline component existing on the surface of the substrate becomes unsatisfactory, and the water repellency of the film cannot be sufficiently maintained. Particularly, the acid concentration of the aqueous acid solution is preferably in the range of 0.01 to 50% by weight.

As the acid component, various inorganic acids and organic acids can be used alone or in combination of two or more. For example, as the inorganic acid, sulfuric acid, sulfurous acid, hydrochloric acid,
Nitric acid, nitrous acid, phosphoric acid, phosphorous acid, chloric acid, chlorous acid,
Hypochlorous acid, perchloric acid, chromic acid, dichromic acid, carbonic acid,
Examples thereof include boric acid, hydrogen sulfide, and silicon hydride. Sulfuric acid is particularly preferably used because it exhibits good effects and is easily available. Examples of the organic acid include sulfonic acids such as methanesulfonic acid, paratoluenesulfonic acid and alkylbenzenesulfonic acid, carboxylic acids such as formic acid, acetic acid and butyric acid, and other amino acids and phenols. Sulfonic acids and carboxylic acids are preferably used.

The surface treatment by immersing the base material in the aqueous acid solution may be performed at any temperature in the range of 0 to 100 ° C., and the immersing time may be the removal of the alkaline component existing on the surface of the base material or the base material. The surface is sufficiently cleaned, and generally, the higher the processing temperature is, the shorter the time is.
Time or more is suitable.

Formation of Water-Repellent Film After completion of the above-mentioned surface treatment, the organosilazane polymer represented by the general formula (1) is dissolved in a suitable organic solvent, coated on a substrate, and heated. A water repellent film is formed by curing. This coating can be performed by any means such as dip coating, spray coating, roller coating and the like.

[0025]

EXAMPLES Synthesis Example 1 Fluorine-containing chlorosilane represented by the formula: C ₈ F ₁₇ CH ₂ CH ₂ SiCl ₃ , 92.4% by weight and the following formula:

[0026]

[Chemical 5]

A reaction vessel was charged with 60 g of a mixture of dimethylpolysiloxane of 7.6% by weight and 200 ml of trichlorotrifluoroethane. After cooling this to 5 ° C., ammonia gas was blown in while keeping the liquid temperature at 20 ° C. or lower to react for 4 hours. Then, the mixture was heated under reflux for 30 minutes to remove excess ammonia dissolved in the liquid, and after cooling, ammonium chloride as a by-product was filtered off to obtain a colorless and transparent fluorinated polysilazane solution. This was diluted with trichlorotrifluoroethane to a concentration of 1% by weight to prepare a water repellent solution.

Synthesis Example 2 Mixture of 89% by weight of methyltrichlorosilane and 11% by weight of dimethylpolysiloxane used in Synthesis Example 60
g and 200 ml of trichlorotrifluoroethane were used to synthesize a polysilazane solution in the same manner as in Synthesis Example 1, and the polysilazane solution was diluted with trichlorotrifluoroethane to a concentration of 1% by weight to prepare a water repellent solution. did.

Synthesis Example 3 A fluorine-containing polysilazane solution was synthesized in the same manner as in Synthesis Example 1, using 60 g of the fluorine-containing chlorosilane used in Synthesis Example 1 and 200 ml of trichlorotrifluoroethane.
This was diluted with trichlorotrifluoroethane to a concentration of 1% by weight to prepare a water repellent solution.

Example 1 A slide glass plate (76 × 26 × thickness 1.3 mm) was dipped in a 10% aqueous solution of sulfuric acid (pH: 0.01 or less) for about 20 hours and then washed with deionized water to prepare 100 Drying was performed at 0 ° C. for 1 hour.
At this time, the sodium concentration on the surface of the slide glass plate is
It was determined by measuring the photoelectron intensity of surface sodium by SCA analysis and calculating the atomic%. The results are shown in Table 1.
Shown in. Then, the water repellent solution of Synthesis Example 1 (fluorine-containing polysilazane concentration: 1.0% by weight) was applied by a dipping method, heat treatment was performed at 100 ° C. for 2 hours, and after cooling, the uncured portion of the surface was wiped off. , A water-repellent film was formed. The contact angle of water (initial contact angle) and the initial falling angle of this film-formed slide glass plate were measured, and the following durability test was conducted. The contact angle of water after the test was measured, and the contact angle retention ratio ( %) Was calculated. The results are shown in Table 1.

The initial sliding angle was measured using a static friction coefficient measuring device (manufactured by Shinto Kagaku Co., Ltd.) under the condition of 25 ° C.
50 ml of deionized water was dropped on the glass plate and the temperature was about 2 ° /
It was determined by measuring the angle at which a water drop fell when the glass plate sample was raised at a speed of 2 seconds. It can be said that the smaller the sliding angle is, the better the water repellency of the film is. The durability test was performed by wiping the film forming surface of the slide glass plate 20 times with a constant force using a wet cotton cloth.

Example 2 A water-repellent film was formed in the same manner as in Example 1 except that the slide glass plate was immersed in a 0.1% aqueous solution of sulfuric acid (pH: 2.0), and the same measurement was carried out. I went. The results are shown in Table 1.

Example 3 A water-repellent film was formed in the same manner as in Example 1 except that the slide glass plate was immersed in 10% methanesulfonic acid aqueous solution (pH: 0.1), and the same measurement was carried out. I went.
The results are shown in Table 1.

Example 4 A water-repellent film was formed in the same manner as in Example 1 except that the slide glass plate was immersed in a 10% aqueous acetic acid solution (pH: about 2.0), and the same measurement was carried out. went. The results are shown in Table 1.
Shown in. In Examples 1 to 4 above, the surface roughness of the slide glass was measured using a three-dimensional surface roughness measuring instrument (Kosaka Laboratory Ltd. SE-30k) after the treatment with the acid aqueous solution. It was confirmed that there was almost no change from the surface roughness before the treatment and that surface erosion hardly occurred.

Comparative Example 1 A water-repellent film was formed in the same manner as in Example 1 except that the slide glass plate was immersed in tap water (pH: about 7.0), and the same measurement was carried out. . The results are shown in Table 1.

Comparative Example 2 A slide glass plate similar to that used in Example 1 was wiped with a paper gauze impregnated with toluene and dried,
The water repellent was dipped in the same manner as in Example 1 to form a water repellent film, and the same measurement as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 3 A water-repellent film was formed in the same manner as in Example 1 except that the slide glass plate was immersed in a 0.1% acetic acid aqueous solution (pH: 4.0), and the same measurement was carried out. I went. The results are shown in Table 1.

Comparative Example 4 A slide glass plate was dipped in a 10% hydrofluoric acid aqueous solution (pH: 0.01 or less) for 10 seconds, washed with deionized water, and then washed with 1
It was dried at 00 ° C. for 1 hour. The maximum erosion depth on the surface of the obtained slide glass plate was about 2000Å, and the transparency was impaired. Further, a water-repellent coating was formed on this glass plate in the same manner as in Example 1, and the same measurement as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 5 The water repellent solution obtained in Synthesis Example 2 (fluorine-containing polysilazane concentration: 1.0% by weight) was dip-coated on a slide glass plate treated with a 10% sulfuric acid aqueous solution as in Example 1. 1
Heat treatment was performed at 00 ° C. for 2 hours, the temperature was lowered, and then the uncured portion of the surface was wiped off to form a water-repellent film, and the same measurement as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 6 The water repellent solution obtained in Synthesis Example 3 (fluorine-containing polysilazane concentration: 1.0% by weight) was dip-coated on a slide glass plate treated with a 10% sulfuric acid aqueous solution as in Example 1. 1
Heat treatment was performed at 00 ° C. for 2 hours, the temperature was lowered, and then the uncured portion of the surface was wiped off to form a water-repellent film, and the same measurement as in Example 1 was performed. The results are shown in Table 1.

[0041]

[Table 1]

As is clear from the results shown in Table 1 above, the contact angle retention rate after the durability test was 90% or more by the immersion treatment with an acidic aqueous solution having a pH of 3.0 or less other than hydrofluoric acid, and the coating film It is recognized that the durability of is improved. Further, when the treatment is performed using the aqueous solution of hydrofluoric acid (Comparative Example 4), a good water-repellent coating is formed as in Examples 1 to 4, but in this case, large irregularities are formed on the surface. Therefore, the transparency is impaired and it is not practical. The glass plate of Comparative Example 5 exhibits a good contact angle retention rate as in Example 1, but the initial contact angle cannot be a sufficient value because the coating does not contain a perfluoroalkyl group, and Since the falling angle of water droplets is also inferior, sufficient water repellency is not exhibited. Although the glass plate of Comparative Example 6 exhibits a good initial contact angle, it has an inferior water drop sliding angle and does not exhibit sufficient water repellency. That is, it can be considered that the organosiloxane unit represented by the general composition formula (3) is required in the film.

[0043]

EFFECTS OF THE INVENTION According to the present invention, the durability of the water-repellent film formed on the substrate such as glass is improved and the water-repellent effect is continuously exhibited. The labor required can be reduced, and the consumption of the water repellent can be saved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Kuwata 1 Hitomi, Osamu Matsuida-cho, Usui-gun, Gunma 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Ai Kobayashi Toyota-cho, Toyota City, Aichi Prefecture No. 1 Toyota Motor Co., Ltd. (72) Inventor Kazuo Tojima No. 1 Toyota-cho, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Yasushi Yamazawa No. 1 Toyota-cho, Aichi Prefecture Toyota Car Co., Ltd. (72) Inventor Takashi Ito 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. The inorganic base material has a pH of 3.0 excluding hydrofluoric acid.
After surface treatment by immersing in the following acidic aqueous solution, the treated surface is treated with the following general formula (1): In the formula, R ¹ and R ² may be the same or different,
A hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, R ³ is a hydrogen atom or an alkyl group, and R f is a perfluoroalkyl group having 1 to 20 carbon atoms. Or it is a C2-C35 perfluoroalkyl ether group, Q is a C2-C5 divalent organic group, a is an integer of 1-3, and b is 0-. 2 is an integer of 2 and a + b is 1 to 3, c is an integer of 0 to 2, d is an integer of 1 to 3 and c + d is 1 to 3, and m and A water-repellent treatment method for an inorganic base material, characterized in that a water-repellent film is formed by applying a solution of an organosilazane polymer represented by: