Abstract: Polyvinyl butyrals (PVBs) with improved thermal stability and improved light resistance contain as stabilizers polynuclear phenols which phenolic radicals have a quaternary carbon atom in the para-position to the phenolic hydroxyl group and if desired in combination with synergistically acting, nitrogen-containing, sulfur-containing or phosphorus-containing co-stabilizers of the types a) to d). The use of the resulting films of low yellowness as interlayer films having substantially reduced yellowing for the production of laminated glasses and glass composites of silicate glass sheets is described.