Water repellent glass plates

First, a glass plate 1 ( FIGS. 1A-1B ) for a paned window on an automobile was prepared, and then it was washed well and dried. Then, 99 weight percent of a chemical absorbent having a reactive group (e.g., epoxy group) in a functional portion at one of its ends and an alkoxylsilyl group at the other of its ends, as shown in a chemical structure below (chemical 1), and 1 weight percent of a silanol condensation catalyst (e.g., dibutylstannum diacetylacetonate) were weighed. Both reagents were dissolved in a silicone solvent (e.g., hexamethyldisiloxane solvent) to obtain the chemical absorbent liquid with a total concentration of 1 weight percent (the concentration of the chemical absorbent can be 0.5 to 3%).

The chemical absorbent liquid composition was applied to the surface of the glass plate 1 , and then the reaction was carried out for about two hours in the atmospheric air (45% relative humidity). A number of hydroxyl groups 2 are included on the surface of the glass plate 1 ( FIG. 1A ), and the —Si(OCH 3 ) groups in the chemical absorbent composition and the hydroxyl groups 2 undergo a dealcoholization reaction (in this case, —CH 3 OH is removed) in the presence of the silanol condensation catalyst to form the bonding shown in the chemical structure below (chemical 2). This forms a chemical absorbent monomolecular film 3 containing epoxy groups covalently bound over the surface of the glass plate with a film thickness of about 1 nanometer as shown in FIG. 1B .

The glass surface is washed with a chloric organic solvent, such as chloroform, and the surface of glass plate 4 is covered with a chemical absorbent monomolecular film having an epoxy group on its surface ( FIG. 1B ).

When the plate is left in the atmospheric air without washing, the solvent is evaporated and the chemical absorbent remaining on the surface of the glass plate reacts with the moisture in the air. An ultra thin polymeric coating film of the chemical absorbent is formed on the surface of the particle. In addition, the glass plate with this coating film had a similar reactivity.

Also, an alumina micro particle 5 ( FIGS. 2A-2B ) having an average diameter of about 100 nm, which is smaller than visible light wavelength was prepared and dried. The size of the transparent micro particle may be smaller than visible light wavelength. Then, a chemical absorbent liquid with a total concentration of 1 weight percent (the concentration of the chemical absorbent is 0.5 to 3%) was prepared by weighing 99 weight percent of a chemical absorbent having an amino or imino group (—NH), which can react with an epoxy group is included at one end of the reagent and an alkoxysilyl group at the other of its ends as shown in a chemical structure below (chemical 3) having an amino group at one of its ends; and weighing 1 weight percent of an organic acid (e.g., acetic acid) which can be used as a silanol condensation catalyst; and then dissolving both reagents in a mixed solvent of equal parts of silicone and dimethylformamide (e.g., 50% of hexamethyldisiloxane solvent and 50% of dimethylformamide solvent).

The anhydrous alumina micro particle was mixed with the chemical absorbent liquid while stirring, and then reacted in atmospheric air (45% relative humidity) for about two hours. A number of hydroxyl groups 6 are included on the surface of the alumina micro particle ( FIG. 2A ), and the —Si(OCH 3 ) groups in the chemical absorbent and the hydroxyl groups undergo a dealcoholization reaction (in this case, —CH 3 OH is removed) in the presence of the acetic acid to form the bondings shown in the chemical structure below (chemical 4). A chemical absorbent monomolecular film 8 is formed containing amino groups 7 chemically bound over the surface of the micro particle with a film thickness of about 1 nanometer.

The micro particle is washed with a chloric organic solvent, such as chloroform or n-methylpyrrolidinone, under stirring. An alumina micro particle 9 with the surface covered with a chemical absorbent monomolecular film having a reactive group such as an amino group on its surface was produced ( FIG. 2B ) in the same way as Example 1. When using a chemical absorbent composition containing an amino group, a tin series catalyst can produce a sediment. An organic acid, such as acetic acid, can provide better results. In addition, while an amino group includes an imino group, a pyrrole derivative or an imidazole derivative could be used as a compound including an imino group or an amino group. Furthermore, when a ketimine derivative was used, an amino group was more easily introduced by hydrolysis after the coating film formation.

In addition, a monomolecular film formed with this process, as is the case with example 1, did not affect the particle diameter nor the surface shape of an alumina micro particle because the film was extremely thin with nanometer-level film thickness. When the monomolecular film was left in atmospheric air without washing, the solvent was evaporated and the chemical absorbent remaining on the surface of the particle reacted with the moisture in the air, then an alumina micro particle with an ultra thin polymeric coating film on its surface composed of the said chemical absorbent was obtained. However, it had almost the same reactivity.

Next, an ethanol dispersion of the alumina micro particle covered with the chemical absorbent monomolecular film containing the amino group was applied on the surface of the glass plate covered with a chemical absorbent monomolecular film containing said epoxy group. The ethanol was evaporated and heated with about 100 degrees for about 30 minutes. The epoxy group and the amino group underwent an addition reaction as shown in the chemical formula below (chemical 5), and the glass and the alumina particle were bound and fixed through the linking of the two monomolecular films.

Furthermore, when washed with the organic solvent, such as chloroform, the excess alumina particles covered with a chemical absorbent monomolecular film containing unreacted amino group was eliminated. Then a glass plate 10 , where only one layer of the alumina micro particle 5 was covalently bound on the surface of the glass plate 1 through the intermediary of the two monomolecular films, was produced ( FIG. 3A ).

Next, a chemical absorbent which can have a critical surface energy of 10 mN/m or less when forming a monomolecular film. A chemical absorbent can include a fluorocarbon group (functional portion) and a chlorosilyl group (active portion), such as CF 3 (CF 2 ) 7 (CH 2 ) 2 SiCl 3 . The chemical absorbent was dissolved in nonaqueous organic solvent (such as dehydrated nonane) to prepare the chemical absorbent. When the chemical absorbent liquid was applied on the surface of the glass plate and the reaction was carried out under a dried air atmosphere (a relative humidity of 30% or less was preferable), the dehydrochloric reaction occurred between the chlorosilyl group (SiCl) of the chemical absorbent and the amino group (—NH 2 ) on the surface of the alumina micro particle. The alumina micro particle 5 on the surface of the glass plate 4 was covered with a number of amino groups 7 ( FIG. 3A ), and then bonds shown in a chemical formula below (chemical 6) were produced over the surface of the alumina micro particle. Next, when washed with a chlorofluorocarbon series solvent, a glass plate 12 covered with a water repellent monomolecular film 11 of the chemical absorbent was produced.

When the plate is left in the atmospheric air without washing, the solvent is evaporated and the chemical absorbent remaining on the surface of the glass plate reacted with the moisture in the air to form an ultra thin polymeric coating film of the chemical absorbent. In addition, the glass plate with this coating film had a similar reactivity.

Since the thickness of the monomolecular film was about 1 nm at most, a convexo concave of about 50 nm on the surface of the glass plate of the alumina micro particle was not affected significantly. In addition, because of the effect of the convexo concave, the apparent water-droplet contacting degree of the glass plate was about 160 degrees, and super water repellency was realized.

In addition, the critical surface energy of the monomolecular film of CF 3 (CF 2 )(CH 7 ) 2 SiCl 3 formed on the base material with a flat surface was about 6 mN/m, and the maximum water-droplet contacting degree was about 115 degrees.

Since the alumina micro particle has higher hardness than the glass and it is covalently bound to the surface of the glass plate, the friction resistance was improved notably compared to the monomolecular film of CF 3 (CF 2 )(CH 7 ) 2 SiCl 3 directly formed on the surface of the glass plate.

Furthermore, since the thickness of the produced coating film was about 100 nm total, the transparency of the glass plate having the micro particle coating was not decreased or damaged.

After preparing a glass plate having only one layer of the alumina particle film covalently bound to its surface as described in example 1, a chemical absorbent liquid with a concentration of about 1 weight percent (the chemical absorbent concentration was 0.5 to 3%) was prepared by weighing 99 weight percent of a reagent having a fluorocarbon group (—CF 3 ) at an end of the reagent and an alkoxysilyl group at the other end, such as CF 3 (CF 2 ) 7 (CH 2 ) 2 Si(OCH 3 ) 3 being the reagent, and 1 weight percent of dibutylstannum diacetylacetonate as a silanol condensation catalyst; and then dissolving them in a silicone solvent, such as a hexamethyldisiloxane solvent. Then the glass plate, wherein only one layer of the alumina micro particle was covalently bound to the surface, was soaked in the chemical absorbent liquid and the reaction was carried out for about two hours; then the plate was washed to eliminate the excess chemical absorbent; and then the alkoxysilyl group undergoes a dealcoholization reaction with the amino group to obtain the water repellent glass.

In contrast to example 1, by forming a chemical absorbent monomolecular film containing an amino group on the surface of the glass plate with the same method, then forming a chemical absorbent monomolecular film containing an epoxy group on the surface of the alumina micro particle, then fixing one layer of an alumina micro particle on the surface of the glass plate with the same method, and finally, reacting the CF 3 (CF 2 ) 7 (CH 2 ) 2 SiCl 3 chemical absorbent, a water repellent glass was produced. This reaction allows the SiCl group to react with the epoxy group.

In above examples 1 to 3, the compounds shown in (chemical 1) and (chemical 3) were used as chemical absorbents having reactive groups and alkoxysilyl group at opposing ends. Also, the compounds shown below (1) to (16) could be used as chemical absorbents with or instead of the above compounds.

(CH 2 OCH)CH 2 O(CH 2 ) 7 Si(OCH 3 ) 3   (1)

(CH 2 OCH)CH 2 O(CH 2 ) 11 Si(OCH 3 ) 3   (2)

(CH 2 CHOCH(CH 2 ) 2 )CH(CH 2 ) 2 Si(OCH 3 ) 3   (3)

(CH 2 CHOCH(CH 2 ) 2 )CH(CH 2 ) 4 Si(OCH 3 ) 3   (4)

(CH 2 CHOCH(CH 2 ) 2 )CH(CH 2 ) 6 Si(OCH 3 ) 3   (5)

(CH 2 OCH)CH 2 O(CH 2 ) 7 Si(OC 2 H 5 ) 3   (6)

(CH 2 OCH)CH 2 O(CH 2 ) 11 Si(OC 2 H 5 ) 3   (7)

(CH 2 CHOCH(CH 2 ) 2 )CH(CH 2 ) 2 Si(OC 2 H 5 ) 3   (8)

(CH 2 CHOCH(CH 2 ) 2 )CH(CH 2 ) 4 Si(OC 2 H 5 ) 3   (9)

(CH 2 CHOCH(CH 2 ) 2 )CH(CH 2 ) 6 Si(OC 2 H 5 ) 3   (11)

H 2 N(CH 2 ) 5 Si(OCH 3 ) 3   (12)

H 2 N(CH 2 ) 7 Si(OCH 3 ) 3   (12)

H 2 N(CH 2 ) 9 Si(OCH 3 ) 3   (13)

H 2 N(CH 2 ) 5 Si(OC 2 H 5 ) 3   (14)

H 2 N(CH 2 ) 7 Si(OC 2 H 5 ) 3   (15)

H 2 N(CH 2 ) 9 Si(OC 2 H 5 ) 3   (16)

Here, the (CH 2 OCH)-group represents a functional group shown in a chemical structure below (chemical 7), the (CH 2 CHOCH(CH 2 ) 2 )CH-group represents a functional group shown in a chemical structure below (chemical 8).

Further, in above examples 1 and 3, CF 3 (CF 2 ) 7 (CH 2 ) 2 SiCl 3 was used as a fluorocarbon series chemical absorbent, however, the compounds shown below (21) to (26) could also be used with or instead of the above compounds.

CF 3 CH 2 O(CH 2 ) 15 SiCl 3   (21)

OF 3 (OH 2 ) 3 Si(OH 3 ) 2 (OH 3 ) 15 SiCl 3   (22)

CF 3 (CF 2 ) 5 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 SiCl 3   (23)

CF 3 (CF 2 ) 7 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 SiCl 3   (24)

CF 3 COO(CH 2 ) 15 SiCl 3   (25)

CF 3 (CF 2 ) 5 (CH 2 ) 2 SiCl 3   (26)

Further, in above example 2, CF 3 (CF 2 ) 7 (CH 2 ) 2 Si(OCH 3 ) 3 was used as a fluorocarbon series chemical absorbent, however, the compounds shown below (31) to (42) could also be used with or instead of the above compounds.

CF 3 CH 2 O(CH 2 ) 15 Si(OCH 3 ) 3   (31)

CF 3 (CH 2 ) 3 Si(CH 3 ) 2 (CH 2 ) 15 Si(OCH 3 ) 3   (32)

CF 3 (CF 2 ) 5 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 Si(OCH 3 ) 3   (33)

CF 3 (CF 2 ) 7 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 Si(OCH 3 ) 3   (34)

CF 3 COO(CH 2 ) 15 Si(OCH 3 ) 3   (35)

CF 3 (CF 2 ) 5 (CH 2 ) 2 Si(OCH 3 ) 3   (36)

CF 3 CH 2 O(CH 2 ) 15 Si(OC 2 H 5 ) 3   (37)

CF 3 (CH 2 ) 3 Si(CH 3 ) 2 (CH 2 ) 15 Si(OC 2 H 5 ) 3   (38)

CF 3 (CF 2 ) 5 (OH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 Si(OC 2 H 5 ) 3   (39)

CF 3 (CF 2 ) 7 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 Si(OC 2 H 5 ) 3   (40)

CF 3 COO(CH 2 ) 15 Si(OC 2 H 5 ) 3   (41)

CF 3 (CF 2 ) 5 (CH 2 ) 2 Si(OC 2 H 5 ) 3   (42)

In addition, in above examples 1 to 3, metal carboxylate, metal carboxylate ester, polymeric metal carboxylate, metal carboxylate chelate, titanic acid ester, and titanic acid ester chelate can be used as silanol condensation catalysts. More specifically, stannous acetate, dibutylstannicdilaurate, dibutylstannicdioctate, dibutylstannicdiacetate, dioctylstannicdilaurate, dioctylstannicdioctate, dioctylstannicdiacetate, dioctanoic acid stannous, lead naphthenate, cobalt naphthenate, ferric 2-ethylhexanoate, dioctylstannum bisoctylthioglycolate, dioctylstannum maleate, polymeric dibutylstannum maleate, polymeric dimethylstannum mercaptopropionate, dibutylstannum bisactylacetate, dioctylstannum bisacetyllaurate, tetrabutyltitanate, tetranonyltitanate, and bis(acetylacetonitrile) di-propyltitanate, were can be used as silanol condensation catalysts.

A solvent for preparing the film coating can include a chemical absorbent selected from an alkoxysilane series or chlorosilane series solvent, nonaqueous organic chlorinate solvent, hydrocarbonate solvent, fluorocarbonate solvent, silicone series solvent, or mixtures thereof. Further, the solvent boiling point is recommended at about 50 to 250° C., in cases where increase of particle concentration by evaporating the solvent without washing process is intended.

Specifically, usable solvents are: nonaqueous petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzene, isoparaffin, n-paraffin, decalin, industrial gasoline, nonane, decane, kero, dimethyl silicone, phenyl silicone, alkyl modified silicone, polyether silicone, and dimethylformamide, for chlorosilane series solvents.

Further, alcoholic solvents such as methanol, ethanol, or propanol, or mixtures thereof can be used in addition to the above solvents, in cases where alkoxysilane series absorbent are used and an organic film is produced by evaporating the solvent.

In addition, chlorofluorocarbon solvents, Fluorinert (3M Co. product), Afluid (Asahi Glass Co. product) are on the market as fluorocarbon solvents. Further, these solvents can be used alone or, when having good solubility in each other, in mixtures of two or more. Furthermore, organic chlorinate solvents such as chloroform may be added.

In contrast, when a ketimine compound, organic acid, aldimine compound, enamine compound, oxazoline compound, or aminoalkylalkoxysilane compound was used instead of the above silanol condensation catalysts, the processing time was shortened to about a half to two thirds under same concentration.

Furthermore, when the silanol condensation catalyst was used in mixture with compounds such as a ketimine compound, organic acid, aldimine compound, enamine compound, oxazoline compound, or aminoalkylalkoxysilane compound (mixing ratio range can be 1:9 to 9:1, however, 1:1 was generally preferable), the processing time was shortened further several fold and the coating film production time was shortened up to a fraction.

For example, by substituting the H3 provided by Japan Epoxy Resin Co. to the silanol catalyst of dibutylstannum oxide while keeping other conditions unchanged, the results were almost the same except the reaction time was shortened to about one hour.

Furthermore, by substituting the mixture of the H3, ketimine compound, provided by Japan Epoxy Resin Co., and dibutylstannum bisacetylacetonate, which is a silanol catalyst, (mixing ratio was 1:1) to the silanol catalyst, while keeping other conditions unchanged, the results were almost the same except the reaction time was shortened to about 20 minutes.

Consequently, as stated above, it was found that a ketimine compound, organic acid, aldimine compound, enamine compound, oxazoline compound, or aminoalkylalkoxysilane compound has higher activity than silanol condensation catalyst.

Furthermore, it was found that using a mixture of the silanol condensation catalyst and any one of a ketimine compound, organic acid, aldimine compound, enamine compound, oxazoline compound, or aminoalkylalkoxysilane compound results in much higher activity.

In addition, the ketimine compound usable here is not limited and others are listed below such as:

2,5,8-triaza-1,8-nonadiene, 3,11-dimethyl-4,7,10-triaza-3,10-tridecadiene, 2,10-dimethyl-3,6,9-triaza-2,9-undecadiene, 2,4,12,14-tetramethyl-5,8,11-triaza-4,11-pentadecadiene, 2,4,15,17-tetramethyl-5,8,11,14-tetraaza-4,14-octadecadiene, 2,4,20,22-tetramethyl-5,12,19-triaza-4,19-trieicosadiene.

In addition, a usable organic acid includes, but not limited to, a formic acid, acetic acid, propionic acid, butylic acid, or malonic acid, and the like, and each one of them nearly had the same effect.

In addition, the above three examples were described with alumina micro particle as example, any kind of micro particle having a surface which contains an active hydrogen such as a hydrogen of a hydroxyl group, an amino group, or an imino group can be used.

Specifically, particles other than alumina, such as silica or zirconia, may be used as a transparent particle that is harder than glass material.

A driving test was conducted in rainy weather by loading the water repellent glass plates, which was produced by the same conditions as described in example 1, having a water-droplet contacting degree of about 160 degrees (for practical use, water-droplet contacting degrees of 150 degrees or more provided the same result) to the automobile front paned window (also called windshield; angle of gradient is about 45 degrees), the side paned window (angle of gradient is about 70 degrees), and the rear paned window (angle of gradient is about 30 degrees).

First, the rain droplet adhesion when parking was evaluated, and all paned windows had almost no adhesion of droplet with a diameter of 5 mm or more.

Next, a driving test was conducted under 45 km/hour speed and the rain droplet adhesion on the paned windows was evaluated. The side paned window and the rear paned window had almost no adhesion of droplet with a diameter of about 2 mm or more. In addition, during the driving, a number of rain droplets adhered continuously on the windshield, but the droplets with a diameter of about 2 mm or more moved toward the upper direction quickly, then flew away and did not remain on the windshield to an extent that would interfere with the field of vision. Further, when the driving speed was increased to 60 km/hour, the droplets with a diameter of about 2 mm or more were blown away quickly and almost all of them were removed.

Further, the rearward visibility was evaluated with the door mirror through the side paned window plate during the driving test, and neither the deflection of the rearward visibility, nor the deterioration of the visibility by the rain droplets was found significantly.

In addition, under fine weather conditions, the driving visibility with and without the coating film was evaluated. As the transparency of the coating film is 97% or more under the light having a wavelength of 400 nm to 700 nm, deterioration of visibility was not found significantly compared to the automobile having no coating film. In addition, the friction resistance against the windshield wiper was significantly improved compared with the water repellent coating film formed on a glass itself because of the hardness of the alumina micro particle.

From the experiments above, it was confirmed that the automobile according to the present invention provides extremely safe conditions for driving under rainy weather.

The relationship between the water-droplet contacting degree (including additional data obtained by using other materials) and the falling off degree obtained from various experiments was shown FIG. 3 . As clearly shown in this data, when the droplet contacting degree is 150 degrees or more, most of the droplets on the paned window run off by themselves.