Process for the production of modified, partially acetalized polyvinyl alcohol films

Claim 1

A process for adjusting the adhesive force of plasticizer-containing, partially acetalized polyvinyl alcohol film to the surfaces of inorganic glasses to certain desired pummel adhesion values required for a given application in the production of composite safety glass panes, which comprises adding to a pre-existing partially acetalized polyvinyl alcohol resin composition, which composition contains an adhesive force adjusting silane and which composition is not capable of producing a film with the desired pummel adhesion value, from 0.005 to 0.7% by weight, based on the total weight of the partially acetalized polyvinyl alcohol resin of: (a) a silicon-functional silane or a mixture of silicon-functional silanes to reduce the adhesive force of the film prepared from the resulting resin composition; or (b) a silicon-organofunctional silane or a mixture of silicon-organofunctional silanes to increase the adhesive force of the film prepared from the resulting resin composition; or (c) a mixture of at least one silicon-functional silane with at least one silicon-organofunctional silane to regulate the adhesive force of the film prepared from the resulting resin composition, to obtain the desired pummel adhesion values; the silicon-functional silane in (a) or (c) being represented by the general formula: Rn -- Si -- R'.sub.4-n wherein R represents alike or different, saturated, straight-chain or branched alkyl groups of 1-18 carbon atoms, R' represents halogen, or identical or different saturated alkoxy or oxyalkoxy groups of 1-8 carbon atoms, and n is an integer from 0 to 3, and the silicon-organofunctional silane in (b) or (c) is represented by the general formula: ##STR3## wherein R 1 represents a hydrolyzable group of Cl or OR"; with R" representing a C 1-18 alkyl or oxyalkyl group; R' represents an alkyl group of 1-18 carbon atoms; A represents a bivalent alkylene group of 1-10 carbon atoms which may be branched; Z represents a functional group selected from the group consisting of ##STR4## -- CH ═ CH 2 , and -- NR'" R"", wherein R'" represents H or aminoalkyl containing 2-8 carbon atoms and R"" is H or R'"; n is an integer from 1 to 3 and p is 1 or when Z is -- CH ═ CH 2 , p is O; and processing the resulting partially acetalized polyvinyl alcohol resin composition into a film with the desired pummel adhesion value; wherein said partially acetalized polyvinyl alcohol resin contains 10 to 25% by weight of vinyl alcohol groups, and said partially acetalized polyvinyl alcohol resin composition contains from 18 to 65 parts by weight of plasticizer per 100 parts by weight of the partially acetalized polyvinyl alcohol resin.