Process for the collective pretreatment of steel, galvanized steel, magnesium and aluminum before bonding to rubber

A process for the production of a rubber-to-metal bond comprising at least the following steps:

• a) treating one or more metal parts comprised of a metal selected from the group consisting of steel, galvanized steel, aluminum, and magnesium with an aqueous solution with a pH value of 3.5 to 5.5 which consists essentially of:
• (i) 4 to 20 g/l of phosphate ions,
• (ii) 0.1 to 1 g/l of free or complexed fluoride and
• (iii) 0.04 to 1 g/l of nitrate ions,
• (iv) 0.05 to 0.5 g/l of molybdate ions, and
• (v) 0.5 to 2 g/l of one or more nonionic surfactants.
• b) after said treating, rinsing said one or more metal parts, and
• c) after said treating and said rinsing, vulcanizing on said one or more metal parts a member selected from the group consisting of natural and synthetic rubbers, wherein said vulcanizing employs a member selected from the group consisting of primers and binders.