Patent GB-998221-A (GB)
Title: Improvements relating to process and product for modifying the surface characteristics of pristine glass surfaces
Inventor: LAGALLY PAUL
IPC: C08F8/12
Filed: 1963-02-20
Abstract: A composition for protecting glass surfaces comprises an aqueous solution of a partially hydrolysed copolymer of a vinyl trialkoxy silane, maleic anhydride and at least one vinyl fatty acid ester. Preferably the copolymer also contains vinyl formate units.  The composition is prepared by copolymerizing in a common water-miscible solvent a mixture of maleic anhydride, a vinyl trialkoxy silane, at least one vinyl ester of a long chain fatty acid and preferably also vinyl formate.  The organic solvent is removed and the product dried at a temperature below 100 DEG  C. whereby the silicon ester groups are almost completely replaced by silanol groups and the latter are partly transformed into siloxane groups.  The copolymer is then hydrolysed to open the anhydride rings and hydrolyse the formate groups.  The aqueous composition thus formed is sprayed on to the surface of glass containers when the residual silanol groups react with the silanol groups located on the glass surface to form siloxane groups.  The treated glass container is then preferably further treated with superheated or pressurized steam whereby the siloxane groups in the surface coating are transformed into silanol groups which then react with silanol groups in the glass surface.  These surface coatings have excellent adhesion to water base glues for securing labels.ALSO:A composition for protecting glass surfaces comprises an aqueous solution of a partially hydrolysed copolymer of a vinyl trialkoxy silane, maleic anhydride and at least one vinyl fatty acid ester.  Preferably, the copolymer also contains vinyl formate units.  The composition is prepared by copolymerizing a mixture of maleic anhydride, a vinyl trialkoxy silane, at least one vinyl ester of a long chain fatty acid and preferably also vinyl formate employing free radical polymerization and using a common water-miscible solvent.  The organic solvent is removed by washing, and the product dried at a temperature below 100 DEG  C. whereby the silicon ester groups are almost completely replaced by silanol groups and the latter are partly transformed into siloxane groups.  The copolymer is dissolved in boiling water containing an aqueous base whereby the anhydride rings are opened and the formate groups are hydrolysed.  The aqueous composition thus formed may then be sprayed on to the surface of glass containers when the residual silanol groups react with the silanol groups located on the glass surface to form siloxane groups.  The treated glass container is then preferably further treated with superheated or pressurized steam, whereby the siloxane groups in the surface coating are transformed into silanol groups which then react with silanol groups in the glass surface. The vinyl alkoxy silane may be vinyl triethoxy, triisopropoxy, trimethoxy or tributoxy silane, while the long chain fatty acid vinyl ester may be vinyl stearate, vinyl palmitate, vinyl oleate and may be partly replaced by lower vinyl esters such as vinyl acetate, propionate or octanoate. The usual free radical catalysts are used during the polymerization step.