Process for the production of silicic acid heteropolycondensates useful as coating materials

Claim 1

A process for the production of a silicic acid heteropolycondensate, comprising: simultaneously condensing (a) at least one substituted silane corresponding to the general formula SiR.sub.n R".sub.(4-n) (I) in which R is selected from the group consisting of hydrogen, halogen, alkoxy and --NR' 2 , wherein R' is hydrogen and/or lower alkyl, R" is selected from the group consisting of alkyl, alkenyl, aryl and aralkyl and n is an integer of from 1 to 3; (b) at least one functional silane corresponding to the general formula SiR.sub.n (R'" Y).sub.(4-n) (II) in which R is as defined above, R'" is selected from the group consisting of alkylene, phenylene, alkyl phenylene and alkylene phenylene; Y is selected from the group consisting of halogen, amino, anilino, aldehyde, keto, carboxy, hydroxy, mercapto, cyano, hydroxyphenyl, diazo, carboxylic acid alkyl ester, sulphonic acid (--SO 3 H) and phosphoric acid (--PO 3 H 2 ) groups and n an integer of from 1 to 3; (c) at least one hydrolyzable silicic acid derivative corresponding to the general formula SiR.sub.4 (III) in which R is as defined above, with the proviso that not all the radicals R are hydrogen; and (d) optionally at least one compound selected from the group consisting of substantially involatile oxides of elements selected from the group consisting of Groups Ia to Va, IVb and Vb of the Periodic System and compounds of elements selected from the group consisting of Groups Ia to Va, IVb and Vb of the Periodic System which form a substantially involatile oxide in the presence of at least the quantity of water stoichiometrically required for hydrolysis and in the presence of a condensation catalyst and/or a solvent, the quantities in which said components (a) to (d) are used being selected in such a way that the silicic acid heteropolycondensate formed contains, based on oxide units from 60 to 90% by weight of said component (a), from 1 to 15% by weight of said component (b), from 1 to 30% by weight of said component (c) and from 0 to 40% by weight of said component (d), thereby producing a relatively nonporous coating containing a quantity of reacting coupling sites sufficient to fixedly attach a biological, chemical or biochemical material thereto.