Patent ID: 7763121

Claim:
A method of producing a rubber part having an aluminum-based metal component and a rubber component, said aluminum-based metal component being made of aluminum or an aluminum alloy, the method comprising steps of: forming a chemical film A on a surface of the metal component by bringing a treatment agent into contact with the surface; and integrating the metal component and the rubber component through the chemical film A, the chemical film (A) comprising zinc fluoride, molybdenum and aluminum fluoride, wherein zinc of the zinc fluoride, the molybdenum and aluminum of the aluminum fluoride are present in the chemical film in a content ratio of zinc/molybdenum/aluminum=4.0 to 5.5/3.0 to 5.0/ 0.5 to 1.5 on a mass basis, the treatment agent comprising: (a) zinc sulfate aqueous solution containing 13 to 17% by weight of zinc sulfate heptahydrate; (b) ammonium fluoride aqueous solution containing 8 to 12% by weight of ammonium fluoride; and (c) sodium molybdate aqueous solution containing 3 to 7% by weight of sodium molybdate dihydrate, which are mixed in a mass ratio of (a)/(b)/(c)=5.25 to 8.75/2.25 to 3.75/1.50 to 2.50, the treatment agent containing 4.55 to 17.85 g/liter of zinc sulfate heptahydrate, 1.2 to 5.4 g/liter of ammonium fluoride and 0.3 to 2.1 g/liter of sodium molybdate dihydrate.