| 摘要 |
1,207,620. Inhibiting foam formation. HERCULES Inc. 11 Sept., 1968 [13 Sept., 1967; 23 July, 1968], No. 43268/68. Headings C3P and C3R. Foam formation in an aqueous system having foam-forming tendencies is controlled by adding to the aqueous system a foam-controlling amount of a stable dispersion comprised of (A) at least one normally solid hydrophobic thermoplastic synthetic polymer in finely divided form as the dispersed phase and (B) an organic liquid as the continuous phase, the organic liquid being a non-solvent for the hydrophobic synthetic polymer(s). The polymer (A) may be a normally solid homopolymer derived from an α-monoolefinic hydrocarbon having 2-20 carbon atoms, copolymers (including graft polymers, addition polymers and block polymers) of these monomers, copolymers of these monomers with butadiene, polybutadiene, polyisoprene, polyethylene terephthalate and nylon 6, nylon 6/6 and nylon 6/10. The polymer particles are of an average primary particle size within the range 0À02-50 microns and comprise between 2 and 25% by weight of the dispersion. Many organic liquids (B) are particularly mentioned including non-polar and water-immiscible polar organic liquids. The dispersion may include 0À01-10% by weight of a surface active agent, of which many are particularly mentioned. The dispersion itself may amount to between 0.003 and 1% by weight of the aqueous system to which it is added. Examples are directed to controlling the foaming of aqueous solutions of alkyl benzene sodium sulphonate or black pulp mill liquor encountered in paper-making, with the aid of dispersions containing: (2 and 3) finely divided polypropylene in xylene or in a commercially available mixture of aromatic hydrocarbons containing a small amount of 2-ethyl hexanol to wash the polypropylene particles; (4-7) finely divided polypropylene, polyethylene, copolymer of propylene and ethylene, or polyethylene terephthalate in white mineral oil (mixture of aliphatic hydrocarbons), with optionally sorbitan monooleate; and (8-11) finely divided polyethylene in heptane and, optionally, silicone oil, sorbitan monooleate, or sorbitan monooleate and the polyoxyethylene adduct of sorbitan monooleate. |
