SURFACE TREATMENT COMPOSITIONS

Abstract: Composition for treatment of hydrophilic surfaces particularly glass surfaces to render them hydrophobic, said composition comprising a liquid mixture formed by admixture of a liquid organic alcohol containing from 1 to 14 carbon atoms and an organic sulphonate containing from 1 to 14 carbon atoms with a polymeric siloxane, and then with a liquid fluorinated hydrocarbon. Optionally, the composition may also contain an organic titanate.

Description: TITLE SURFACE TREATMENT COMPOSITIONS DESCRIPTION The present invention relates to surface treatment compositions. FIELD OF THE INVENTION Glass and ceramic articles typically have hydrophilic surfaces. When water contacts hydrophilic surfaces it tends to adhere to the hydrophilic surfaces. The present invention will henceforth be described with particular reference to treatment of glass surfaces but it is to be understood that it is applicable to treat¬ ment of hydrophilic surfaces generally. Rain drops falling through the atmosphere collect particles of dirt and dust from the atmosphere. When the rain drops fall onto glass, the water adheres to the hydrophilic surface of the glass and the water remains there until it evaporates, leaving behind a deposit of dirt and grime. It follows that windows and other outdoor glass surfaces need frequent cleaning. Thus, there is a need to render the surface of glass hydrophobic to reduce the adherence of water thereto and the deposition of dirt and grime thereon. SUMMARY OF THE INVENTION In accordance with one aspect of the present invention there is provided a composition for treatment of hydro¬ philic surfaces to render them hydrophobic which comprises a liquid mixture formed by admixture of a liquid organic alcohol containing from 1 to 14 carbon atoms and an organic sulphonate containing from 1 to 14 carbon atoms with a polymeric siloxane, and then with a liquid fluorinated hydrocarbon. DESCRIPTION OF THE INVENTION The composition of the present invention is preferably made by firstly incorporating a quantity of pure concentrated sulphuric acid in a liquid organic alcohol containing from 1 to 14 carbon atoms such that a proportion, preferably a minor proportion, of the alcohol reacts with the sulphuric acid to produce the correspon¬ ding organic sulphonate. The mixture may be refluxed for a period of time to obtain a satisfactory degree of reaction of the sulphuric acid. Whilst the alcohol may contain from 1 to 14 carbon atoms it preferably contains from 2 to 5 carbon atoms. Further, the alcohol is preferably an unsubstituted and saturated aliphatic alcohol. The preferred alcohol is isopropyl alcohol. The sulphuric acid i * s preferably analytical reagent grade. Thus, there is produced a liquid mixture of an organic alcohol and the corresponding organic sulphonate in which mixture the organic sulphonate may be present in a number of isomeric forms. To the mixture so obtained there may be added slowly the siloxane component so that the siloxane becomes dispersed in the alcohol-sulphonate mixture to form a cloudy liquid. This may be done at room temperature. The siloxane is typically a trimethyl poly siloxane which is preferably of the branched chain type. The siloxane may contain from 1 to 6 million dimethyl siloxane units in a polymeric chain but preferably contains from about 5 to 50 dimethyl siloxane units such as from 12 to 20 dimethyl siloxane units. 5 Further, the polymeric siloxane can be end blocked by hydroxyl groups. A preferred polysiloxane compound is trimethyl poly- siloxane having a molecular weight of about 1200 which corresponds to about 16 dimethyl siloxane units. 10 Subsequently, there is added a liquid fluorinated hydrocarbon. This compound may have some chloro substituents but it preferably has at least as many fluorine atoms as chlorine atoms. Apreferred compound is, trichlorotrifluoroethane. The addition of a quantity 15. - of the fluorinated hydrocarbon causes the liquid composition to clear. The compositions of the present invention preferably have incorporated therein from 10 to 40% by weight of the organic alcohol, from 5 to 20% by weight of the 20 polymeric siloxane compound, and from 0.5 to 4% by weight of the organic sulphonate compound. In the compositions of the present invention, the sulphonate compound cleaves bonds by which hydrogen atoms are attached to oxygen atoms on a hydrophilic 25 surface. This renders the surface reactive with dimethyl or trimethyl silane groups at the ends of chains of the polymeric siloxane compound. Further, the organic alcohol forms an azeotrope with water on the surface. Since liquid organic alcohols are 30 quite volatile, the azeotrope evaporates fairly readily and thus the water is removed from the hydrophilic surface. Still further, the fluorinated hydrocarbon forms a volatile liquid mixture with grease on the hydrophilic surface and removes the grease from the surface by evaporation. The composition described above will render a hydrophilic surface hydrophobic and cause it to repel water. However, for increased durability of the hydrophobic treatment it is preferred to include in the composition n organic titanate such as a tetra alkyl titanate preferably tetra isopropyl titanate. Conveniently this component is incorporated in the composition of the present invention after the addition of the polymeric siloxane and before the addition of the fluorinated hydrocarbon. Preferably, the organic titanate is incorporated in an amount from 0.1 to 2% by weight of the composition. The fluorinated hydrocarbon makes up the balance of the composition. The present invention will now be illustrated by the following example. EXAMPLE A composition in accordance with the present invention was prepared by incorporating a quantity of analytical reagent grade concentrated sulphuric acid into a quantity of anhydrous isopropyl alcohol. The mixture was refluxed for 40 minutes to convert the sulphuric acid into an isomeric mixture of isopropyl sulphonates in an amount calculated to be 2 grams while the residual isopropyl alcohol was calculated to weigh 27.5 grams. Then, at room temperature, 10 grams of trimethyl- polysiloxane having a molecular weight of about 1200 was slowly incorporated into the composition to form a cloudy liquid mixture. Then 0.5 grams of tetra isopropyl titanate was incorporated into the mixture. Finally, 60 grams of trichlorotrifluoroethane was incorporated into the mixture. The final mixture was a clear homogeneous liquid composition. The composition prepared above was applied in a continuous layer to a glass surface by means of a soft cloth to form a substantially even coating on the surface. The coating was left for 20 minutes to allow volatiles to evaporate. Then the glass surface was polished with a clean cloth which removed residual coating material. The glass surface became clean and clear. It was found that the treated glass surface retained water much less than an untreated glass surface. Modifications and variations such as would be apparent to a skilled addressee are deemed within the.scope of the present invention.

Claims: CLAIMS 1. A composition for treatment of hydrophilic surfaces to render them hydrophobic characterised in that it comprises a liquid mixture formed by admixture of a liquid organic alcohol containing from 1 to 14 carbon atoms and an organic sulphonate containing from 1 to 14 carbon atoms with a polymeric siloxane, and then with a liquid fluorinated hydrocarbon. 2. A composition according to Claim 1, characterised in that a quantity of pure concentrated sulphuric acid is incorporated in the liquid organic alcohol such that a proportion of the alcohol reacts with the sulphuric acid to produce the corresponding organic sulphonate. 3. A composition according to Claim 2, characterised in that 3 minor proportion of the alcohol is reacted with the sulphuric acid to produce the corresponding organic sulphonate. 4. A composition according to any one of the preceding claims, characterised in that the organic alcohol contains from 2 to 5 carbon atoms. 5. A composition according to any one of the preceding claims, characterised in that the organic alcohol is an unsubstituted and saturated alihpatic alcohol. 6. A composition according to Claim 5, characterised in that the alcohol is isopropyl alcohol. 7. A composition according to any one of the preceding claims, characterised in that the polymeric siloxane is a trimethyl polysiloxane. 8. A composition according to Claim 7, characterised in that the trimethyl polysiloxane is of the branched chain type. 9. A composition according to Claim 7 or 8, chracter- ised in that the trimethyl polysiloxane contains from 1 to 6 million dimethyl siloxane units in a polymeric chain. * 10. A composition according to Claim 9, characterised in that the trimethyl polysiloxane contains from 5 to 50 dimethyl siloxane units in a polymeric chain. 11. A composition according to Claim 10, characterised in that the trimethyl polysiloxane contains from 12 to 20 dimethyl siloxane units in a polymeric chain. 12. A composition according to any one of Claims 7 to 11, characterised in that the trimethyl polysiloxane is trimethyl polysiloxane having a molecular weight of about 1200. 13. A composition according to any one of the- ' .preceding claims, characterised in that the polymeric siloxane component is added slowl to the organic sulphonate and organic alcohol mixture to form a cloudy liquid. 14. A composition according to any one of the preceding claims, characterised in that the fluorinated hydrocarbon contains some chlorine atoms. 15. A composition according to Claim 14, characterised in that the fluorinated hydrocarbon has at least as many fluorine atoms as chlorine atoms. 16. A composition according to Claim 15, characterised in that the fluorinated hydrocarbon is trichlorotrif- luoroethane. 17. A composition according to any one of the preceding claims, characterised in that it contains from 10 to 40% by weight of the organic alcohol, from 5 to 20% by weight of the polymeric siloxane, from 0.5 to 4% by weight of the organic sulphonate and sufficient fluorinated hydrocarbon to obtain a clear composition. 18. A composition according to any one of the preceding claims, characterised in that it also contains an organic titanate such as a tetra alkyl titanate. 19. A composition according to Claim 18, characterised in that the organic titanate is a tetra isopropyl titanate. 20. A composition according to Claim 8 or 19, characterised in that the organic titanate is incorporated in the composition after addition of the polymeric siloxane and before addition of the fluorin¬ ated hydrocarbon. 21. A composition according to any one of Claims 17 to 20. characterised in that the organic titanate is present in an amount from 0.1 to 2% by weight of the composition. 22. A method of making a composition for treatment of hydrophilic surfaces characterised in that it comprises (1) forming an admixture of a liquid organic alcohol containing from 1 to 14 carbon atoms and organic sulphonate containing from 1 to 14 carbon atoms, (2) adding to the mixture of (1) a polymeric siloxane, and (3) adding to the mixture of (2) a liquid fluorinated hydrocarbon, and (4) , optionally, between steps (2) and (3) adding to the mixture an organic titanate.

Inventors: FREW JEREMY GEORGE MCKENZIE, FREW, JEREMY, GEORGE, MCKENZIE
Applicants: PROTECTIVE RESEARCH IND LIMITE, PROTECTIVE RESEARCH INDUSTRIES LIMITED
Application year: 1986
Main classification: C09K3
IPC codes: C09K3