| 摘要 |
<p>1311421 Melamine - formaldehyde - filled moulding compositions STANDARD OIL CO 23 April 1971 [24 April 1970] 10947/71 Heading C3R A moulding composition is prepared by mixing a filler with a resinous melamine-formaldehyde, syrup, drying the mixture and mixing it with 1-50 wt. per cent of the total composition of the same dried mixture which has been cured and pulverized, as reactive filler. In examples a resin syrup is prepared from melamine and formaldehyde in 1 : 2À2 molar ratio; it is mixed with alpha cellulose and dried to give "popcorn", which is then ground; some of this powder is mixed with Zn stearate, phthalic anhydride and TiO 2 to give a standard moulding powder; the standard moulding powder is cured, by heating at 345‹ F. at 2000 p.s.i. for 3 mins. (Example 2), or by radio-frequency heating (Example 7), and ground to below 100 micron particle size, to give the reactive filler; ground "popcorn" (Examples 2-5, 12 and 13), or standard moulding powder (Examples 7-11) are mixed with the reactive filler to give moulding powders which are moulded and cured at 310‹ F./1400 p.s.i./3 mins. or 345‹ F./ 3000 p.s.i./3 mins.; the powders may also contain carbon black. A urea-formaldehyde or phenol-formaldehyde resin may be used instead of part or all of the melamine-formaldehyde resin of the moulding composition.</p> |
