| 摘要 |
1489501 Precipitating polymer and concentrate powders HERCULES Inc 25 March 1975 [26 March 1974] 12407/75 Heading C3P A method of preparing polypropylene in the form of substantially spherical particles of 1-100 microns in diameter comprises preparing a homogeneous solution of 7À5-25% by wt. of polypropylene in a normally liquid organic material, which is a solvent for polypropylene at 120‹ C. or higher and which has a solubility parameter of 6À6-10À3 (Cal./c.c)¢, a dipole moment of 0-1À7 Debye units and a hydrogen bonding parameter of 0-18À7 cm.<SP>-1</SP> and thereafter cooling the solution to room temperature under quiescent conditions. The solvent may be a paraffin hydrocarbon, an aromatic hydrocarbon, a halogenated hydrocarbon a cycloaliphatic hydrocarbon, an aliphatic alcohol or a mixture thereof and in particular, as exemplified, may be n-decane, n-octanol, chlorobenzene, hexadecane, cyclohexane, xylene and n-heptane. Colour concentrates may be formed by incorporating a dye or pigment in the solution prior to precipitation. |
