| 摘要 |
1494410 Melamine-formaldehyde moulding compositions RUTGERSWERKE AG 13 June 1975 [14 June 1974] 25408/75 Heading C3R A moulding composition comprises (a) a melamine-formaldehyde (MF) resin of M : F molar ratio 1 : 1À5-2À5 which, when hardened, is not damaged or discoloured by exposure to air at 200‹ C. for 2 hours (e.g. an unmodified unetherified resin), (b) a latent accelerator which is a melamine salt of a mono- or di-carboxylic acid; (c) an inorganic filler having an oil adsorption number (i.e. milligrams of linseed oil adsorbed by one gram of filler without its becoming viscous) of 20-40 (e.g. Ca or Mg carbonate, oxide or sulphate); (d) an inorganic filler thermostable at 250‹ C.; (e) an external (mould) lubricant of which at least 50 wt. per cent is a carboxyorganosiloxane esterified with a C 1-4 alcohol, and, if necessary; (f) an internal lubricant. The preferred proportions, of the total composition, are: (a) 25-60 wt. per cent; (b) 0À01-2 wt. per cent; (c) plus; (d) not more than 65 wt. per cent, in 1 : 1-10 wt. ratio; (e) 0À1-1À5 wt. per cent; and (f), if present, 0À1-3 wt. per cent. Any further component (e) may be an organic metal salt, e.g. a C 12-20 fatty acid salt of Mg, Ca, Zn or Al; colorants and fibrous reinforcement may also be added. In the examples moulding compositions are prepared by mixing, and drying if necessary, (a) 30 or 40 p.b.w. of an MF resin of M : F ratio 1 : 1À6, as a powder or a 60% aqueous syrup; (b) 0À1 to 0À2 p.b.w. of melamine benzene-sulphonate; (c) 13-30 p.b.w. of CaCO 3 ; (d) 20 or 40 p.b.w. of Ca metasilicate; (e) 0À2 to 0À4 p.b.w. each of an ester-containing siloxane and Mg stearate, and (f) 0 or 0À5 or 1 p.b.w. of dioctyl phthalate, with 6-9 p.b.w. of a grey mixture of ZnS, Fe 2 O 3 and carbon black. |
