JPH11130470A - Water repellent glass and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a glass excellent in wear resistance, decreased in the change of contact angle and critical inclination angle with time by forming an undercoat layer by applying a polysilazane on the surface of a glass substrate and a water repellent layer thereon. SOLUTION: The glass is a water repellent glass having the water repellent layer formed by applying a coating solution containing a fluoroalkyl silyl compound expressed by formula I or formula II, having a fluoroalkyl group in the molecule and in the concentration of 0.25-25 mol/L on the undercoat layer formed by applying the polysilazane on the surface of the glass substrate and having 100-500 nm thickness. The polysilazane is hexamethylsilazane, 1,3- diphenyltetramethyldisilazane or the like and is used as a solution having 0.2-20 wt.% solid portion concentration. In the formulas, (n) represents 3-12, R represents methylene group, ethylene group or the like, X represents H, an alkyl group, a cycloalkyl group, an aryl group or the like, (p) represents 0, 1 or 2 and Y represents a 1-3C alkoxy group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-repellent glass, and more particularly, to a water-repellent glass plate suitable for a vehicle or an architectural window which can ensure a comfortable visual field even during rainfall or is suitable for windows which are hardly stained. .

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. Hei 4-239633 discloses a method in which silicate glass and fine particles are mixed to form a submicron to micron-order uneven film, and then a polymer film layer containing a fluorocarbon group and a siloxane group or a chemically adsorbed single molecule. A water-repellent treatment method for providing a layer is described. In the uneven film, the convex portions are selectively damaged by wear, but the concave portions can escape the wear. For this reason, the water-repellent group bonded to the convex portion disappears, but the water-repellent group in the concave portion remains without being deteriorated, so that the apparent equilibrium contact angle is greatly reduced by the action of the water-repellent group in the concave portion. It is considered that they are kept near the initial value without any change.

On the other hand, Japanese Patent Application Laid-Open No. Hei 4-338137 discloses that the number of water-repellent groups per unit surface area (density) is increased, and the water-repellent groups are chemically bonded to the glass surface to form a contact angle and a water droplet. This is an attempt to prevent the abrasion resistance deterioration of the critical inclination angle, which is an index of the ease with which water flows down.A silica undercoat is prepared by a sol-gel process using silicon alkoxide as a raw material, and a water repellent is placed on the undercoat layer. Is applied, followed by heat treatment at a temperature of 300 ° C. or less, at which the organic water-repellent group is not decomposed.

[0004] Industrially produced sheet glass for buildings and automobiles generally has a soda-lime glass composition. However, it has long been known that alkali (mainly sodium) in a glass composition is easily displaced and eluted by reaction with water in the air, causing defects such as cutting siloxane bonds and scorching of glass. ing. A siloxane bond is also formed between the organosilicon compound such as a water repellent applied to the surface of the glass plate and the silanol on the glass surface. There was a problem that the group was eliminated and the water repellency was reduced.

[0005] For this reason, a method has been devised in which a silica undercoat layer is provided as an alkali barrier in order to prevent elution of alkali. In this respect, the undercoat layer of the water-repellent film described in JP-A-4-338137 also lacked the denseness of silica in this respect, and was susceptible to the decrease in water repellency due to alkali elution.

JP-A-5-97474 proposes the production of a silica film containing a water-repellent film on the glass surface by a film formation method by liquid phase adsorption.

[0007]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 4-239 is disclosed.
In the concavo-convex film represented by No. 633, as the wear deterioration progresses, the water-repellent groups in the convex portions disappear, but the water-repellent groups in the concave portions remain without being deteriorated by abrasion, so that the apparent contact angle does not change significantly. , The critical tilt angle increases, that is,
There was a problem that it was difficult for water drops to flow down.

On the other hand, in the technique of Japanese Patent Application Laid-Open No. 4-338137, although the density of the water-repellent groups and the chemical bond between the water-repellent groups and the undercoat silica are high, the sol-gel silica film is sufficiently dense when heated at about 300 ° C. Since the film quality was not obtained, the wear durability was insufficient. In addition, there is a problem that alkali is eluted through the undercoat film and deterioration is large in a boiling resistance test.

The liquid phase adsorption film forming method described in Japanese Patent Application Laid-Open No. 5-97474 can form a relatively good water-repellent film, but it is necessary to immerse the glass plate in the processing solution for a long time to form the film. In addition, there is a problem that a large cost is required for processing large glass such as architectural and automotive glass.

An object of the present invention is to solve these conventional problems and to produce a water-repellent glass excellent in abrasion resistance and having little change over time in a contact angle and a critical inclination angle at a low cost. .

[0011]

SUMMARY OF THE INVENTION The present invention is a water-repellent glass comprising an undercoat layer formed by applying polysilazane on the surface of a glass substrate, and a water-repellent layer thereon.

In the present invention, first, polysilazane is applied to the surface of a glass substrate to form an undercoat layer. Polysilazane has a Si-N bond in the molecule. When heated in an inert gas, it becomes a polymer having Si-N and Si-C bonds. When heated in the atmosphere, Si-N decomposes. , Forming a Si-O bond, resulting in silica. Since this silica film has a polymerized polysilazane in advance,
It is denser and has higher hardness than silica synthesized from silicon alkoxide or the like. This polysilazane is applied to a glass surface and baked under heating to obtain a dense and high-hardness silica film.

Further, polysilazane immediately after coating has many silazane groups remaining, and easily reacts with free silanol to form a siloxane bond. Accordingly, after coating the polysilazane on the glass surface, a water repellent, preferably a water repellent having a fluoroalkyl group in the molecule, acts immediately as a second layer, preferably before the coating layer dries, and is heated and baked. By doing so, the fluoroalkyl water-repellent group can be chemically bonded at high density and firmly.

Here, polysilazane refers to poly (perhydrosilazane). For an example of polysilazane synthesis, see J. AMERIC
AN CERAMIC SOCIETY, 73 [1] 170-172 (1990) or JP-A-5-163174. In particular, JP-A-5-238827 discloses a synthesis example of polysilazane which can obtain a dense and high-hardness film even at a low temperature of about 150 ° C. Some of these polysilazanes are already commercially available.

As polysilazane, for example, hexamethyldisilazane, CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ Si (N
H) _3/2 , NH [Si (CH ₃ ) ₂ CH ₂ Cl] ₂ , 1,3-divinyl-1,1,3,3-tetramethyldisilazane, 1,
3-diphenyltetramethyldisilazane, octamethylcyclotetrasilazane, 1,1,3,3-tetramethyldisilazane, polytitanosilazane, polydisilacyclobutasilazane, polyalkoxysilylalkylenedisilazane, hexamethylcyclotrisilazane, Silazane such as organotetrachlorosilazane and hydridothiosilazane are exemplified.

The polysilazane can be applied as it is to the surface of the glass plate, but is usually dissolved in a solvent so that the SiO ₂ solid content is 0.2 to 20% by weight, more preferably 0.5 to 7% by weight. The solvent used for the coating liquid is an aromatic hydrocarbon such as xylene, toluene, and benzene in which polysilazane is easily soluble, or an ether such as ethyl ether and tetrahydrofuran, and a halogenated hydrocarbon such as methylene chloride and carbon tetrachloride. Alternatively, alkyl carbitol acetate and the like are desirable. These solvents may be used alone or as a mixture of two or more. It is necessary to sufficiently remove water that may be contained in the solvent in advance.

It is desirable that the substrate glass is previously polished and cleaned using cerium oxide or another polishing agent, thoroughly washed with water until no polishing agent residue remains, and rinsed with pure water. Drying must be sufficient to ensure that no moisture remains on the glass surface.

The polysilazane undercoat solution may be applied by a method using a coating apparatus such as a roll coater, a gravure coater, a bar coater, a die coater, a spin coater, a curtain coater, etc., or by a method such as spraying, dipping, and flow coating. . Also,
A printing method such as curved surface printing, flexographic printing, and screen printing may be used.

The thickness of the polysilazane undercoat is 50
0 nm or less is desirable, and 100 nm or more is desirable. This is because, when the film thickness is large, a “rainbow” may be generated due to the interference effect and the appearance may be impaired. On the other hand, when the film thickness is smaller than 100 nm, uniform coating becomes difficult, and the polysilazane is coated only in an island shape. This is because it may not be done.

In the present invention, as the water repellent applied on the undercoat layer, a water repellent having a fluoroalkyl group in a molecule is preferably used.
Or the fluoroalkylsilyl compound shown by (2) can be mentioned.

[0021]

Embedded image CF ₃ — (CF ₂ ) _n —R—SiX _p Y _3-p (1) (where n is an integer of 3 to 12, R is a methylene group, an ethylene group, or a silicon atom and an oxygen atom A group containing
Is a substituent selected from an alkyl group, a cycloalkyl group, an allyl group, or a derivative thereof, or hydrogen, p is 0, 1 or 2, and Y is an alkoxy group having 1 to 3 carbon atoms.

[0022]

## STR2 ## _{CF 3 - (CF 2) n} -R-SiX p Cl 3-p (2) ( wherein, n represents 3 to 12 integer, R represents a methylene group, an ethylene group or a silicon atom and an oxygen atom, A group containing
Is H or a substituent selected from an alkyl group, a cycloalkyl group, an allyl group or a derivative thereof;
Or 2)

Since many silazane groups remain on the surface of the polysilazane film (wet coating film) immediately after application,
The silazane group reacts violently with a water repellent, fluoroalkylalkoxysilane, or with a fluoroalkylchlorosilane and a trace amount of water in a solvent or air, as shown in the following formula (3) or (4), to form a siloxane. It is considered that bonding occurs, and as a result, the polysilazane film and the water-repellent film are strongly bonded. In the formulas (3) and (4), R _f represents a fluoroalkyl group, and R represents an alkyl group.

[0024]

化 Si-NH-Si≡ + 2 (RO-Si-R _f ) → 2 (≡Si-O-Si-R _f ) + R ₂ NH (3)

Embedded image ≡Si-NH-Si≡ + 2 ( Cl-Si-R f) + 2H 2 O → 2 (≡Si-O-Si-R f) + NH 3 + 2HCl (4)

The concentration of the water repellent in the coating liquid, preferably a water repellent having a fluoroalkyl group in the molecule, varies from 25 mol to 0.1 mol / L of the solution, depending on the molecular structure.
Desirably, it is 25 mol. This is because when the concentration exceeds 25 mol, the polymerization reaction between the water repellent molecules becomes remarkable, and when the concentration is less than 0.25 mol, the surface coating density of the water repellent decreases, so that the initial critical inclination angle increases. This is because

Further, since the polysilazane immediately after application readily reacts with a compound containing an OH group such as alcohol in addition to water, xylene,
Use aprotic organic solvents such as aromatic hydrocarbons such as toluene and benzene, ethers such as ethyl ether and tetrahydrofuran, halogenated hydrocarbons such as methylene chloride and carbon tetrachloride, and alkyl carbitol acetate. I have to. It is necessary to sufficiently remove the water content of these solvents in advance.

It is preferable to apply the water repellent coating liquid before the polysilazane undercoat film is dried, in other words, in a state where the silazane groups in the undercoat film can freely move in the film. If the polysilazane undercoat film is dried at, for example, 110 ° C. for 10 minutes before the application of the water repellent coating liquid, the obtained water repellent film shows a large initial contact angle and a small initial critical tilt angle, In addition, the contact angle after the wear resistance test is reduced, and the critical inclination angle after the reciprocal wear resistance test is increased, so that the durability is significantly reduced. This is because the silazane group in the polysilazane film does not sufficiently react with the fluoroalkyl group that is the water-repellent group in the water-repellent coating liquid due to the drying, and as a result, the density of the water-repellent group per glass plate surface area is small. This is probably because the bonding strength of the water-repellent groups becomes insufficient.

The application of the water-repellent coating solution is performed by using a coating apparatus such as a roll coater, a gravure coater, a bar coater, a die coater, a spin coater, a curtain coater, etc., as in the case of the polysilazane undercoat, or by spraying or dipping. Alternatively, a method such as flow coating may be used. Further, a printing method such as curved surface printing, flexographic printing, and screen printing may be used.

Both the application of the polysilazane undercoat liquid and the application of the water repellent coating liquid are preferably performed in a clean room, and further performed in a room where the relative humidity is controlled to 50% or less, preferably 20% or less. Is preferred.

After the application of the above water repellent coating solution, baking is performed. This heating condition is usually 150 to 500
For 30 seconds to 10 hours, more preferably 200 to 350 hours.
C. for 30 minutes to 3 hours. Before the heating, for example, after applying the water repellent coating liquid, the coating may be once dried at a temperature lower than 150 ° C.

In the present invention, as the glass substrate to be treated,
When a glass sheet that has already been tempered by air cooling or bending is used, if the heating temperature is too high, the heat distortion inside the glass sheet is lost and the tempering is lost. By heating and baking below, a dense and high-hardness silica film and a strong water-repellent film can be obtained.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION

[Example 1] by Tonen made polysilazane PHPS-1 low-temperature type (xylene solution, SiO ₂ solids 20%), SiO ₂
After diluting with xylene so that the solid content becomes a predetermined concentration of 1 to 4%, put into a polyethylene washing bottle and add 3.5 mm.
An undercoat layer was provided by spin coating on the surface of a 150 mm × 150 mm thick soda lime glass plate. The rotation speed was 3000 rpm, and the rotation was performed for 10 seconds. Immediately thereafter, a water-repellent layer was formed by spin-coating a xylene solution having a water-repellent agent of heptadecafluorodecyltrichlorosilane at a concentration of 0.25 to 25 mol / L under the same conditions. The xylene used was a special-grade reagent from which molecular sieve 5A was previously charged to remove water.

This glass plate was placed in a high-temperature dryer at 250 ° C. for 2 hours.
Dried by keeping time. Polysilazane solid concentration of undercoat liquid, thickness of undercoat layer, concentration of water repellent, contact angle (initial value) and critical tilt angle (initial value)
Are shown in Table 1 below.

The film thickness was measured in the vicinity of the center of the coated glass by Alpha Step manufactured by Tenker Co., Ltd. Also,
The contact angle was measured using a contact angle meter manufactured by Kyowa Interface Science.
The critical tilt angle is as shown in Japanese Patent Application Laid-Open No. Hei 7-26751. Using a home-made tool, drop a water droplet on the surface of a horizontally fixed glass plate, gradually tilt the glass plate, and let the water droplet just start moving. Was determined by measuring the angle of inclination of the glass plate.

[0035]

Table 1 ================================== Polysilazane Thickness Water repellent Contact angle Critical tilt angle Appearance Solids (wt%) (nm) Concentration mol / L Initial value Initial value --------------- −−−−−−−−−−−−−−− 1-A 4 500 2.5 105.2 22.8 Light rainbow 1-B 2 300 25.0 107.9 28.0 Good 1-C 2 300 2.5 111.7 21.2 Good 1-D 2 300 0.25 96.6 26.1 Good 1-E 1 100 2.5 97.6 27.6 good ========================================

In Table 1, the undercoat film thickness was 500 n.
In the case of m, interference color was partially observed. A water repellent,
The concentration of heptadecafluorodecyltrichlorosilane is
Approximately 2.5 moles per liter of the solution was the best in terms of the contact angle (initial value) and the critical tilt angle (initial value). However, it seems that this optimum value changes when the types and molecular structures of the water repellent and the solvent change.

Example 2 Tonen polysilazane PHPS
-1 low temperature type (xylene solution, SiO ₂ solid content 20
%) Was diluted with xylene to a solid content of 0.5%, then placed in a polyethylene washing bottle, and spray-coated on one side of a 300 mm square 3.5 mm thick soda lime glass plate. Immediately, it was spray-coated using a xylene solution of heptadecafluorodecyltrichlorosilane (2.5 mol / L) under the same conditions. Drying was performed at 250 ° C in a high-temperature dryer.
Performed by holding for 5 hours.

Example 3 Tonen polysilazane PHPS
-1 low temperature type (xylene solution, SiO ₂ solid content 20
%) Was diluted with xylene to a solid content of 4%, then placed in a box-shaped container without a lid, and a 300 mm square 3.5 mm thick soda lime glass plate was dipped and coated. Immediately, a xylene solution of heptadecafluorodecyltrichlorosilane (2.5 mol / 1 L) was dipped and pulled under the same conditions. Drying was carried out in a high-temperature dryer at 250 ° C. for 1.5 hours.

Example 4 A water-repellent glass was prepared in the same manner as in Example 1, except that heptadecafluorodecylmethyldichlorosilane was used instead of heptadecafluorodecyltrichlorosilane as the water repellent.

Example 1-C (polysilazane solid content 2%,
The water-repellent glass prepared in Examples 2, 3, and 4 was subjected to the following test to evaluate the durability performance. Table 2 shows the results.

Reciprocating abrasion test A flat indenter wound with a flannel cloth was attached to a reciprocating abrasion tester manufactured by Shinto Kagaku and reciprocated under a load of 1 kg. 20,000
The contact angle and the critical inclination angle after the reciprocating test were measured.

Wiper abrasion test A wiper blade rubber was attached to a reciprocating abrasion tester manufactured by Shinto Kagaku Co., Ltd. and reciprocated under a load of 200 g. The contact angle and the critical inclination angle after the 20,000 reciprocation tests were measured.

A test for evaluating the degree of deterioration of the water-repellent film due to alkali elution, in which the glass end surface and the back surface other than the film surface are masked, and the contact angle after immersion in boiling water at 100 ° C. for 6 hours. And the critical tilt angle were measured.

As shown in Table 2, Examples 1-C, 2,
The water-repellent glasses prepared in Nos. 3 and 4 showed little deterioration of the reciprocating wear, the contact angle after the wiper wear, and the critical tilt angle, and were excellent in wear resistance. No decrease in water repellency was observed in the boiling resistance test, indicating that the undercoat layer was acting as a favorable alkali barrier film.

Comparative Example 1 Colloidal silica (Microshear gel DF10-60A manufactured by Asahi Glass) and dimethylpolysiloxane (silicate glass Si-80 manufactured by Tokyo Ohka Kogyo Co., Ltd.)
000) is mixed at a ratio of 1: 1 by weight, and 300 mm
A 3.5 mm thick soda-lime glass plate was coated by a dipping and pulling method, dried, and heated at 300 ° C. for 30 minutes to form an uneven silica film. Next, a water repellent heptadecafluorodecyltrichlorosilane 2% solution in normal hexadecane was applied and heat treated at 200 ° C. for 30 minutes.

As shown in Table 2, although the initial contact angle was large and the initial critical inclination angle was small, the critical inclination angle was increased by the wiper abrasion resistance test, and it became difficult for water droplets to flow down.

Comparative Example 2 Tetraethoxysilane 200
g, heptadecafluorodecyltrimethoxysilane5.
46 g and 426.5 g of ethanol were stirred and mixed in a 1 L beaker for 20 minutes. Further, 83 g of water and 104 g of a 0.1N hydrochloric acid aqueous solution were added, and the mixture was stirred for 2 hours. This was transferred to a plastic bottle and left at 25 ° C. for 24 hours.
A 300 mm square 3.5 mm thick soda lime glass plate is immersed in this solution, pulled up at a pulling rate of 30 mm / min, dried at 120 ° C. for 2 minutes, and then heat-treated at 250 ° C. for 1 hour to obtain a water-repellent glass. Produced.

As shown in Table 2, although the initial contact angle was large and the initial critical tilt angle was small, both the contact angle and the critical tilt angle deteriorated in the wiper abrasion resistance test. Deterioration was also observed in the boiling resistance test, and the denseness and strength of the undercoat layer and the bonding strength of the water-repellent groups were insufficient.

[0049]

[Table 2] ================================== Initial Reciprocating Wear Boiling Wiper Wear After Test After Test Test After −−−−− −−−−− −−−−− −−−−−−− Critical Critical Critical Contact angle Incline angle Contact angle Incline angle Contact angle Contact angle Incline angle −−−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Example 1-C 117.7 21.8 98.1 18.8 116.1 93.9 19.9 Example 2 106.2 26.1 96.6 18.0 107.7 93.5 21.8 26.1 88.9 20.2 106.6 84.0 28.2 Example 4 108.3 20.2 83.7 −− 100.8 79.1 −− Comparative Example 1 120.7 19.8 −− −− 91.2 118.6 38.4 Comparative Example 2 110.1 21.5 −− −− 61.2 30.3 −− ======= ===========================

[0050]

According to the present invention, a water-repellent glass excellent in abrasion durability and with little deterioration of the contact angle and the critical tilt angle can be obtained by a coating method. In particular, the present invention can be applied to a tempered or bent-strengthened glass sheet without losing the tempering.

Claims (4)

[Claims] 1. A water-repellent glass comprising an undercoat layer formed by applying polysilazane on the surface of a glass substrate, and a water-repellent layer on the undercoat layer. 2. The water-repellent glass according to claim 1, wherein the water-repellent layer is formed by applying a water-repellent having a fluoroalkyl group in a molecule. 3. The undercoat layer has a thickness of 500 n.
The water-repellent glass according to claim 1, which is not more than m. 4. The repellent material according to claim 1, wherein a polysilazane is applied to the surface of the glass substrate, a water repellent is applied before the applied layer is dried, and then heated at 200 to 500 ° C. A method for producing an aqueous glass.