Anti-contaminating adsorbed film and method of manufacturing the same

Abstract: This invention provides for an anti-contaminating film which is adsorbed to a substrate surface. The film contains a -Si- group and fluorocarbon group. The -Si- group is covalently bonded to the substrate surface. It also provides a forming method of an anti-contaminating film on a hydrogen active substrate surface by contacting the substrate surface with a non-aqueous solution, containing a surface active material having fluorocarbon groups and chlorosilane groups, the substrate surface having active hydrogen groups, removing unreacted surface active material remaining on the substrate by washing the substrate with a non-aqueous organic solution for making monomolecular a precursor film, reacting chlorosilane groups unreacted in the adsorbed monomolecular a precursor film with water after the removing step, and drying the adsorbed monomolecular film. The above washing step with the non-aqueous organic solution was omitted, fluorocarbon polymer film was formed to the substrate surface.

Description: This invention relates to a method of forming an anti-contaminating film on a substrate surface, said film preferably being a fluorine-based film. This invention further relates to a laminate obtainable by that method. A monomolecular film may be formed on a substrate surface by a chemical adsorption process of a chlorosilane-based surface active material having a long hydrocarbon chain. The substrate can be aluminium or stainless steel and can have hydroxyl groups attached thereto. The method of adsorbing a film to a substrate surface involves a hydrochloric acid removal reaction. This reaction takes place between the hydroxyl groups on the substrate surface and the chlorosilyl groups of the chlorosilane-based surface active material. The surface of an aluminium or a stainless steel substrate is rendered anti-contaminating, heat-resistant, weather-resistant and wear-resistant by coating the substrate surface with a fluorocarbon-based thin film. This is usually done by rendering the surface of an aluminium substrate coarse by means of a wire brush or chemical etching, coating with a primer and then with a paint. The paint is usually prepared by suspending fluorocarbon-based fine particles of ethylene polytetrafluoride in ethanol, drying, and then baking at about 400 °C for about one hour. The procedure fixes the fluorocarbon-based polymer to the substrate surface. Known methods of adsorbing the chlorosilane-based surface active material, however, do not substantially increase the anti-contaminating property of the film. Known methods of coating a fluorocarbon-based coating film, on the other hand, permit ready formation of the anti-contaminating film. However, there is a limit to the degree in which the polymer is anchored to the substrate. Therefore, the method is inadequate when used in manufacturing high mechanical strength apparatuses which require anti-contaminating, heat-resistant, weather-resistant and wear-resistant coatings. These apparatuses include, for example, hot plates, rice cookers and other electric products, vehicles, industrial machines, glass lenses and mirrors. Moreover, with the prior art coating method, a coating film thickness of several tens of microns is necessary at least in order to prevent pin-hole generation. Therefore, prior art films lack transparency or brilliancy. From EP-A-0 326 438 it is known to form a protective film on a magnetic recording medium by preliminarily forming a metal oxide film on the surface thereof and then applying thereto a film of a fluorosilane surface active agent having a fluorine atom at the molecular end. EP-A-0 367 438 discloses a method of forming an adherent fluorosilane layer on a substrate comprising (i) forming on the substrate surface an adherent first layer comprising cured siloxane, and (ii) applying to said first layer a second layer comprising at least one fluorosilane having at least one hydrolysable group attached to a silicon atom and at least one fluorine-containing organic group attached to a silicon atom and donating non-wetting properties to the second layer. According to EP-A-0 491 251, state of the art by virtue of Article 54(3) EPC, a monomolecular film comprising at least two different molecules having different molecular lengths is covalently bonded to a substrate surface. A fluorocarbon-based polymer coating film comprising at least a siloxane film formed on the surface of a substrate as an inner layer and a fluorocarbon-based polymer film formed as an outer layer, both bonded via covalent bonds, is disclosed in EP-A-0 482 613, state of the art according to Article 54(3) EPC. It is the object of the present invention to provide a monomolecular film and/or polymer film which is chemically adsorbed, i.e. covalently bonded, to a substrate surface, which is anti-contaminating and transparent or billiant. According to the present invention this object is achieved with a method of forming a film on a substrate comprising the following steps: (a) contacting the surface of a substrate selected from pottery, porcelain, ceramics, enamelled substrates, glass, stone, wood and plastic having active hydrogen groups with a non-aqueous solution containing a surface active material represented by the formula: CF 3 (CF 2 ) n (R) m SiCl 3 wherein n represents 0 or an integer, R represents an alkylene group, vinylene group, ethynylene group, or a substituted group containing a silicon atom or an oxygen atom, m represents 0 or 1; (b) optionally removing unreacted surface active material remaining on the substrate by washing the substrate with a non-aqueous organic solvent; (c) reacting unreacted chlorosilane groups in the adsorbed film with water; and (d) drying the adsorbed film; provided that the molecules of the surface-active material do not have different molecular chain lengths. The present invention further relates to a laminate obtainable by the present method. According to the present invention the film is either a fluorocarbon-based monomolecular film or a fluorocarbon-based polymer film depending on whether step (b) of the present method is carried out. The substrate is selected from the group consisting of pottery, porcelain, ceramics, enamelled substrates, glass, stone, wood and plastic having on its surface active hydrogen groups. It is preferable in this invention that the active hydrogen groups are selected from the group consisting of hydroxyl groups, amino groups, and imino groups. It is preferable in this invention that the substrate surface made hydrophilic in advance of the contacting step by treating it with oxygen or nitrogen in a plasma or corona atmosphere. According to this invention the surface active material is represented by the formula CF 3 (CF 2 ) n (R) m Si Cl 3 wherein n represents 0 or an integer, R represents an alkylene group, vinylene group, ethynylene group, or a substituted group containing a silicon atom or an oxygen atom and m represents 0 or 1. Accoding to the invention, the above problems can be solved by adsorbing a transparent, anti-contaminating film to a substrate surface. The film comprises a -Si- group which is covalently bonded to the substrate surface. The film also contains fluorine. According to the invention, by using a chemical adsorption method, a hydrophobic film having a uniform thickness in the nanometer range can be formed on the substrate surface without spoiling gloss and transparency. Thus, it is posible to provide a substrate which is highly hydophobic, oil-phobic, substantially pin-hole free, heat resistant, durably brilliant, and contamination free. The invention provides for a method which permits formation of a fluorocarbon-based monomolecular and/or polymer film which is in satisfactorily close contact with the substrate, is substantially pin-hole free and relatively thin. The invention, therefore, improves the performance of apparatuses which have heat-resistant, weather-resistant and wear-resistant coatings. Such apparatuses include, for example, hot plates, rice cookers and other electric products, vehicles, industrial apparatus, glass lenses and mirrors. The method of the present invention comprises the following steps; contacting the hydrogen active substrate surface with a non-aqueous solution, said non-aqueous solution containing a surface active material having fluorine group and chlorosilane group in accordance with the invention, removing the unreacted surface active material remaining on the substrate by washing the substrate with a non-aqueous organic solvent (when this process step is omitted, a fluorine-based adsorbed polymer film is formed on to the substrate), forming a monomolecular or polymer precursor film containing a silanol group at the substrate surface by reacting the chlorosilane groups with water after the removing step, and drying the precursor film. According to the invention, active hydrogen groups are exposed at the substrate surface. The active hydrogen groups are preferably hydroxyl groups, amino groups, or imino groups. Such groups are preferred because they participate readily in the dehydrochloric acid reaction with the chlorosilyl groups of the surface active material. As the substrate pottery, porcelain, ceramics, glass enamelled substrates stone, wood, and plastic can be used. A plastic or like material which does not have any oxide film on its surface can be also used as the substrate. The surface may be rendered hydrophilic, i.e., hydroxyl groups may be introduced, by treating the surface with oxygen in a plasma or corona atmosphere. For example, the surface can be treated at 100 W for 20 min. It is not necessary, however, to surface treat plastics having imino (=NH) groups such as polyamide or polyurethane substrates. Because imino groups have an active hydrogen, it is relatively easy to reduce the groups by initiating the dehydrochloric acid reaction with the chlorosilyl groups of the surface active material. The solution containing the material with a chlorosilyl group may, for example, be a non-aqueous solution containing chloroform. The concentration of the non-aqueous solution which contains the surface active material having a chlorosylil group may vary. However, a solution may be prepared, for example, by dissolving about 1 % by weight of the material to be used into solution. The substrate can be dipped into this solution and held for about 30 min to 2 h. A hydrochloric acid removal reaction proceeds at the substrate surface due to the presence of hydrophilic (-OH) groups. An adsorbed film having material containing a silyl group is thereby formed. A monomolecular adsorbed film is then formed by removing the unreacted surface active material remaining on the substrate. The material is removed by washing the substrate with a non-aqueous organic solvent. The step of washing the substrate surface using a non-aqueous organic solvent process can be omitted, however, when a fluorine-based polymer film is adsorbed to the substrate surface. This invention is described in detail with reference to the following drawings. Figures 1(a) and 1(b) are molecular scale schematic sectional views showing a process as described in Example 1. Figures 2(a) and 2(b) are molecular scale schematic sectional views showing a process as described in Example 2. This invention also provides a film which is covalently bonded to a substrate surface and thus a laminate comprising same. The film contains a -Si- group and fluorine. The -Si- group is covalently bonded to the substrate surface. The fluorochlorosilane-based surface active material according to the present invention is preferably selected from compounds represented by the formulae : CF 3 (CH 2 ) r SiCl 3 , CF 3 (CF 2 ) s O(CH 2 ) t SiCl 3 , CF 3 (CF 2 ) u Si(CH 3 ) 2 (CH 2 ) v SiCl 3 , and CF 3 COO(CH 2 ) w SiCl 3 , wherein is from 1 to 25, s is from 0 to 12, t is from 1 to 20, u is from 0 to 12, v is from 1 to 20 and w is from 1 to 25. These surface active materials are suitably represented by the following examples: CF 3 CH 2 O(CH 2 ) 15 SiCl 3 , CF 3 (CF 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 15 SiCl 3 , CF 3 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 15 SiCl 3 , CF 3 (CF 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 6 SiCl 3 , CF 3 (CF 2 ) 3 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 SiCl 3 , CF 3 COO(CH 2 ) 15 SiCl 3 , CF 3 (CF 2 ) 9 (CH 2 ) 2 SiCl 3 , CF 3 (CF 2 ) 7 (CH 2 ) 2 SiCl 3 , and CF 3 (CF 2 ) 5 (CF 2 ) 2 SiCl 3 . Surface active material containing a fluorine group and a chlorosilyl group according to the invention may be used to impart desirable properties, i.e., they provide a film which is anti-contaminating, transparent, hydrophobic, oil-repelling and which may act as a lubricat. The film according to the invention can be formed and maintained as an ultra thin film. The invention can widely be applied to the following surfaces. Materials made of pottery, porcelain, ceramics, glass, plastic, wood, or stone are applicable as the substrate. The surface of the substrate may be coated with, e.g., paint in advance. Examples of ceramics: cutlery such as a kitchen knife, scissors, a knife, a cutter and a graver; a razor, hair clippers, a saw, a plane, a chisel, a gimlet, a badkin, a bite (cutting tools), an edge of a drill, an edge of a mixer, a juicer, a blade of a mill, a blade of a lawn mower, a punch, a straw cutter, a staple of a stapler, a can opener or a surgical knife. Examples of products in the pottery industry: products made of pottery, glass, ceramics or enamelled products. For example, sanitary potteries (e.g. a chamber pot, a wash-bowl, a bathtub), tableware (e.g. a rice-bowl teacup, a dish (plate), a bowl, a teacup, a glass, a bottle, a coffee-pot (siphon), a pan, an earthenware mortar and a cup), vases (e.g. a flower bowl, a flowerpot and a bud vase), water tanks (e.g. a breeding cistern and an aquarium water tank), chemical experiment appliances (e.g. a beaker, a reactor vessel, a test tube, a flask, a laboratory dish, a condenser, a mixing rod, a stirrer, a mortar, a bat and a syringe) a bath tile, a roof tile, enamelled ware, an enamelled washbowl, an enamelled kettle and an enamelled pan. Examples of ceramics molding parts: dies for press molding, dies for cast molding, dies for injection molding, dies for transfer molding, dies for compression molding, dies for transfer molding, dies for inflation molding, dies for vacuum molding, dies for blow forming, dies for extrusion molding, dies for fiber spinning and a calendar processing roll. Examples of plastics or ceramics forming molds for food such as a cake, cookies, bread, chocolate, jelly, and ice cream; oven ware and ice trays. Examples of resin(s): a polyolefin such as a polypropylene and polyethylene, a polyvinylchloride plastic, a polyamide, a polyimide, a polyamideimide, a polyester, an aromatic polyester, a polycarbonate, a polystyrene, a polysulfide, a polysulfone, a polyethersulfone, a polyphenylenesulfide, a phenolic resin, a furan resin, a urea resin, an epoxy resin, a polyurethane, a silicon resin, an ABS resin, a methacrylic resin, an acrylate resin, a polyacetal, a polyphenylene oxide, a polymethylpentene, a melamine resin, an alkyd resin and an unsaturated polyester cured resin. Examples of rubber: a styrene-butadiene rubber, a butyl rubber, a nitrile rubber, a chloroprene rubber, a polyurethane rubber and a silicon rubber. Examples of ceramics, plastic or resin coating household electric appliances: a refrigerator, a freezer, an air conditioner, a juicer, a mixer, a blade of an electric fan, a lighting apparatus, a dial plate and a dryer for a perm. Examples of plastic sporting goods: skis, a fishing rod, a pole for the pole vault, a boat, a yacht, a surfboard, a fishing line and a float. Examples for application to vehicle parts: (1) ABS resin: a lamp cover, an instrument panel, trimming parts, a protector for a motorcycle. (2) Cellulose plastic: a car mark, a steering wheel (3) FRP (fiber reinforced plastics): a bumper, an engine cover (jacket) (4) Phenolic resin: a brake (5) Polyacetal: wiper gear, a gas valve (6) Polyamide: a radiator fan (7) Polyarylate (polycondensation polymerization by bisphenol A and pseudo phthalic acid): a direction indicator lamp (or lens), a cowl board lens, a relay case (8) Polybutylene terephthalate (PBT): a rear end, a front fender (9) Poly amino-bismaleimide: engine parts, a gear box, a wheel, a suspension drive system (10) Methacrylate resin: a lamp cover lens, a meter pannel and its cover, a center mark (11) Polypropylene: a bumper (12) Polyphenylene oxide : a radiator grill, a wheel cap (13) polyurethane: a bumper, a fender, an installment pannel, a fan (14) Unsaturated polyester resin: a body, a fuel tank, a heater housing, a meter pannel. Examples of plastic or resin coating office supplies: a desk, a chair, a bookshelf, a rack, a telephone stand table, a rule (measure) and a drawing instrument. Examples of building materials: materials for a roof, an outer wall and interiors. Roof materials such as e.g., brick and slate. Outer wall materials such as wood (including processed manufactured wood), mortar, concrete, ceramic sizing, brick, stone, and plastic. Interior materials such as, e.g., wood (including processed wood), plastic and paper. Examples of building stones: granite, marble and others for use as a e.g., building material, an architectural fixture, an ornament, a bath, a grave stone, a monument, a gatepost, a stone wall and a paving stone. Specific examples of the process of chemical adsorption of a water-repelling oil-repelling anti-fogging, anti-contaminating film coating according to the invention will now be described with reference to Figures 1 and 2. Example 1 The glass of a car door mirror having a processed real image side surface was washed with an organic solvent. A solution (non-aqueous solvent) containing 80 % wt n-hexadecane, 12 % wt carbon tetrachloride and 8 % wt chloroform was prepared by using CF 3 (CF 2 ) 7 (CH 2 ) 2 -SiCl 3 as the silane surface active material and dissolving the same at a concentration of 2 % wt. A glass substrate 1, i.e., a car door mirror as shown in Figure 1(a), was dipped into this solution and held at room temperature for one hour. Since the surface of the substrate 1 contained hydroxyl groups 2, a reaction between the chlorosilyl groups of the chlorosilane-based surface active material and the hydroxyl groups occurs to form covalent bonds on the surface. This reaction is represented by the following formula [1]. The glass mirror 1 was then washed with freon 113 to remove the unreacted material remaining on the surface, followed by washing with water or exposure to air containing moisture. The -SiCl group was converted to a -SiOH group as in formula [2]. Each silanol group (-SiOH) was then dehydrated and crosslinked to form a siloxane bond (-SiO-) after drying as in formula [3]. The drying temperature may be room temperature or above. An adsorbed monomolecular film 3 could be obtained on the surface of the glass substrate 1 as shown Figure 1(b). The adsorbed monomolecular film 3 has a fluorine group and is chemically bonded (i.e., covalently bonded) to the substrate 1. The chemical bond is via a siloxane bond. The formation of the chemically adsorbed monomolecular film 3 was assumed by FTIR spectrometry and the thickness was about 1.5 nm. It is firmly bonded such that it will not separate. The treated mirror was compared to a mirror which was not treated. The treated mirror greatly reduced contaminant adherence. In addition, any contaminant which did remain on the treated mirror could be readily removed by wiping with, e.g., a brush. This could be done without causing any scar or scratch on the glass surface. In the above example, only the door mirror glass was treated. However, by chemically adsorbing a monomolecular film to a whole door mirror, the same anti-contaminating effect could be obtained on the frame part of the door mirror as well. Any contaminants remaining on the frame could also be readily wiped off. The above washing step with the non-aqueous organic solvent (freon 113) was omitted, and a fluorine-based polymer film was adsorbed to the substrate surface. The fluorocarbon-based polymer film satisfactorily closely adhered to the substrate. The film was substantially pin-hole free, thin, anti-contaminating, transparent and brilliant. Example 2 A solution was prepared by using CF 3 (CF 2 ) 9 (CH 2 ) 2 -SiCl 3 as the silane surface active material and dissolving the same in freon 113 to a concentration of 2 % wt. A coffee cup as a porcelain substrate 11, as shown in Figure 2(a), was dipped into this solution and held at room temperature for one hour, and then the substrate was washed with "Fluorinert FC72" (products by 3M corp., fluorin-based solution). Since the surface of the substrate 11 contained hydroxyl groups 12, a reaction between the chlorosilyl groups of the chlorosilane-based surface active material and the hydroxyl groups occured as represented by the formula [4]. This reaction proceeded substantially as in the above formulae [1] to [3]. An adsorbed monomolecular film 13 was obtained on the surface of the porcelain substrate 11 as shown Figure 2(b). The adsorbed monomolecular film 13 has a fluorine group and is chemically bonded (i.e., covalently bonded) to the substrate 11. The chemical bond is via a -Si- covalent bond. This chemically adsorbed monomolecular film 13 was assumed by FTIR spectrometry and the thickness was about 1.5 nm. It is firmly bonded such that it will not separate. The treated porcelain substrate was compared to an unreacted or untreated porcelain substrate. The treated substrate greatly reduced contaminant adherence. In addition, any contaminant which did remain onto the treated substrate could be readily removed by wiping with, e.g., a brush. This could be done without causing any scar or scratch on the porcelain surface. The above washing step with the "Fluorinert FC72" was omitted, and a fluorocarbon polymer film was adosorbed to the substrate. The fluorocarbon-based polymer film was in satisfactorily close contact with the substrate. The film was substantially pin-hole free, thin, anti-contaminating, transparent and brilliant. Example 3 A polycarbonate substrate 5 cm on each side and 0.3 cm in thickness was used as a polymer substrate. Its surface was oxidized by oxygen plasma treatment for 10 min with a UV dry stripper at an oxygen supply rate of 1 l/min. Then, in a nitrogen atmosphere and at room temperature, the treated substrate was dipped and held for 60 min in a freon 113 solution containing heptadecafluorodecyl-trichlorosilane at a concentration of 10 -2 mol/l as a chlorosilane-based surface active material having fluoroalkyl groups. Then, non-reacted heptadecafluorodecyl-trichlorosilane was washed out by using freon 113 and then water. A chemically adsorbed monomolecular film containing fluoroalkyl groups bonded via siloxane bonds to the polycarbonate substrate surface was formed. The adsorbed monomolecular film has fluorine atoms and is chemically bonded (i.e., covalently bonded) to the substrate via siloxane bonds. This chemically adsorbed monomolecular film was assumed by FTIR spectrometry and the thickness was about 1.5 nm. It is firmly bonded such that it will not separate. The treated polycarbonate substrate was compared to an untreated polycarbonate substrate. The treated substrate greatly reduced contaminant adherence. In addition, any contaminant which did remain on the treated substrate surface could be readily removed by wiping with e.g. a brush. This could be done without causing any scar or scratch on the polycarbonate surface. The above washing step with the non-aqueous organic solvent (freon 113) was omitted, and a fluorine-based polymer film was adsorbed to the substrate. The fluorocarbon-based polymer film was in satisfactorily close adherence to the substrate. The film was substantially pin-hole free, thin, anti-contaminating, transparent and brilliant. The contact angle of each of the samples of Examples 1 to 3 with respect to super-pure water and to salad oil was examined. It was measured immediately after the formation of the film and after subsequently rubbing the surface 10,000 times with a cloth wetted with water. Table 1 shows the results. Contact angle ( ° ) with respect to water Contact angle ( ° ) with respect to salad oil Initial value After test Initial value After test Example 1 112 109 92 90 Example 2 111 109 93 91 Example 3 110 108 91 89 Example 4 A bath tile as a pottery was washed with an organic solvent, and then dipped and held for about two hours in a non-aqueous solution containing a material having a fluorocarbon group and a chlorosilane group. The solution contained 80 % wt n-hexadecane (or toluene or xylene or dicyclohexyl), 12 % wt carbon tetrachloride and 8 % wt chloroform. The solution was prepared by dissolving; CF 3 (CF 2 ) 5 (CH 2 ) 2 SiCl 3 at a concentration of about 1 % wt. The tile contains many hydroxyl groups on the surface. Therefore, a hydrochloric acid removal reaction was brought about between the -SiCl groups and the hydroxyl groups to produce covalent bonds on the entire surface as in formula [5]. This reaction proceeded substantially as in the above formulae [1] to [3]. A fluorine-containing monomolecular film was formed at a thickness of about 1.5 nm on the tile substrate surface such that it was chemically bonded to the surface. This monomolecular film did not separate in a checkerboard test. The coated tile was used in a bath room. The bath tile gleatly reduced contaminant adherence, and the tile had a clean surface. The above washing step with the non-aqueous organic solvent (freon 113) was omitted, and a fluorine-based polymer film was adsorbed to the substrate. The fluorocarbon-based polymer film was in satisfactorily close adherence to the substrate. The film was substantially pin-hole free, thin, anti-contaminating, transparent and brilliant. Example 5 A sintered kettle (pot) or bowl (hereinafter referred to as porcelain) was prepared. Then, the porcelain was washed with an organic solvent and dipped and held for about two hours in a non-aqueous solution containing a material with a fluorocarbon group and a chlorosilane group in the molecule. The solution contained 80 % wt n-hexadecane (or toluene or xylene or dicyclohexyl), 12 % wt carbon tetrachloride and 8 % wt chloroform. The solution was prepared by dissolving; CF 3 (CF 2 ) 3 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 SiCl 3 at a concentration of about 1 % wt. The porcelain (as well as Al 2 O 3 ceramics) has many hydroxyl groups on the surface. Therefore, a hydrochloric acid removal reaction was brought about between the -SiCl groups and the hydroxyl groups to produce bonds of formula CF 3 (CF 2 ) 3 (CH 2 ) 2 Si(CH 3 ) 2 (CH 2 ) 9 Si(O-) 3 over the entire porcelain surface. This reaction proceeded substantially as in the above formulae [1] to [3]. A fluorine-containing monomolecular film chemically bonded to the surface was formed to with thickness of about 1.5 nm on the porcelain substrate surface. This monomolecular film did not separate in a checkerboard test. The coated pot was used. Any contaminants attached could be reduced greatly compared to that attached to an untreated pot. In addition, any remaining contaminants were readily removed by brushing the surface with a washing brush. This was done without causing any scar or scratch. Fatty matter and rice particles were removed by washing the bowl with water. Further, tannin of tea hardly attached. The above washing step with a non-aqueous organic solvent (freon 113) was omitted, and a fluorine-based polymer film was adsorbed to the substrate. The fluorocarbon-based polymer film was satisfactorily closely adhered to the substrate. The film was substantially pin-hole free, thin, anti-contaminating, transparent and brilliant. Example 6 A processed flooring marble was prepared. The marble was washed with an organic solvent and then dipped for about two hours in a non-aqueous solution containing a material with a fluorocarbon group and a chlorosilane group in the molecule. The solution contained 80 % wt n-hexadecane (or toluene or xylene or dicyclohexyl), 12 % wt carbon tetrachloride and 8 % wt chloroform. The solution was prepared by dissolving; CF 3 (CF 2 ) 9 (CH 2 ) 2 SiCl 3 at a concentration of about 1 % wt. The marble (as well as other stones) contains many hydroxyl groups on the surface. Therefore, a hydrochloric acid removal reaction was brought about between the -SiCl groups and the hydroxyl groups to produce covalent bonds of formula CF 3 (CF 2 ) 9 (CH 2 ) 2 Si(O-) 3 on the entire marble surface. This reaction proceeded substantially as in the above formulae [1] to [3]. A fluorine-containing monomolecular film was formed with a thickness of about 1.5 nm on the marble substrate surface such that it was chemically bonded to the surface. This monomolecular film did not separate in a checkerboard test. The above washing step with a non-aqueous organic solvent (freon 113) was omitted, and a fluorine-based polymer film was adosorbed to the substrate. The fluorocarbon-based polymer film was in satisfactorily close adherence to the substrate. The film was substantially pin-hole free, thin, anti-contaminating, transparent and brilliant. The coated marble was used for a floor. It greatly reduced adherence of contaminants compared to an untreated marble. The marble was clean in surface. In addition, any remaining contaminants could be readily removed by brushing the contaminated surface with a brush. This could be done without causing any scar or scratch. As has been shown above, according to the present invention it is possible to obtain an effective chemically adsorbed film which will readily adsorb to pottery, porcelain, ceramics, enamelled substrates, glass, stone, wood, and plastic substrates which have active hydrogen groups at their surface. Using a compound containing a fluorocarbon group and a chlorosilyl group according to the invention, a fluorocarbon-based film having excellent hydrophilic, oil-repelling, anti-contaminating properties can be formed on the substrate. The film is chemically bonded to the substrate at a high density, is substantially pin-hole free, and has a thin uniform thickness. It is thus an anti-contaminating and brilliant, highly durable, high performance, super-thin, fluorocarbon-based film. As has been shown, the invention is greatly beneficial to industry.

Claims: A method of forming a film on a substrate comprising the following steps: (a) contacting the surface of a substrate selected from pottery, porcelain, ceramics, enamelled substrates, glass, stone, wood and plastic having active hydrogen groups with a non-aqueous solution containing a surface active material represented by the formula: CF 3 (CF 2 ) n (R) m SiCl 3 wherein n represents 0 or an integer, R represents an alkylene group, vinylene group, ethynylene group, or a substituted group containing a silicon atom or an oxygen atom, m represents 0 or 1; (b) optionally removing unreacted surface active material remaining on the substrate by washing the substrate with a non-aqueous organic solvent; (c) reacting unreacted chlorosilane groups in the adsorbed film with water; and (d) drying the adsorbed film; provided that the molecules of the surface-active material do not have different molecular chain lengths. The method according to claim 1, wherein said active hydrogen groups are selected from the group consisting of hydroxyl groups, amino groups and imino groups. The method according to claim 1, wherein the surface of the substrate is made hydrophilic by treating it with oxygen or nitrogen in a plasma or corona atmosphere prior to said contacting (a). A laminate obtainable by the method of any one of claims 1 to 3.

Inventors: MINO NORIHISA, OGAWA KAZUFUMI, SOGA MAMORU, MINO, NORIHISA, OGAWA, KAZUFUMI, SOGA, MAMORU
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1991
Main classification: C09D183
IPC codes: B05D1, C09D183, C08J7, C09D4, C03C17