| 摘要 |
Stoving lacquers comprise 10 to 90 wt. per cent of an oil-modified alkyd resin and 90 to 10 wt. per cent of an etherified aminotriazine resin which has had its free formaldehyde content reduced to less than 1 wt. per cent by one of the following treatments: (a) with a sulphur compound capable of forming a formaldehyde-bisulphite or -sulphoxylate adduct; (b) with sufficient peroxy compound to oxidize the formaldehyde at pH 5 to 9; or (c) with sufficient ammonia to form hexamine with the formaldehyde at 10 DEG to 100 DEG C. A long list of alkyd-forming reactants is given as well as examples of 10 treatments of commercial melamine resins to reduce the formaldehyde content. The lacquers may also contain acrylate or epoxide resins. In the examples, lacquers are prepared from TiO2, a ricinene alkyd in xylene, the various treated melamine resins and isopropyl glycol and coated on glass plates at a thickness of 20 to 30 m and heated for 30 minutes at 90 DEG C. and 30 minutes at 120 DEG C.ALSO:Stoving lacquers comprise 10 to 90 wt. % of an oil-modified alkyd resin and 90 to 10 wt. % of an etherified aminotriazine resin which has had its free formaldehyde content reduced to less than 1 wt. % by certain specified treatments (see Div. C3). In Examples such lacquers also containing TiO2, xylene and isopropyl glycol are coated on glass plates at a thickness of 20 to 30m and heated for 30 minutes at 90 DEG C and 30 minutes at 120 DEG C. |
