| 摘要 |
<p>Solids, liqs. and pastes are incorporated into a polymer at room temp. after cryogenic grinding at a temp. low enough to keep the additives in the solid state throughout grinding. The additives may be pre-mixed, after leaking if necessary. Grinding is pref. carried out in a dehydrated atmos., achieved by refrigerating the air circulating in the grinding or passing it through an absorbing bed of, e.g. silica or Al silicate. The intense cooling necessary is achieved by the injection of liq. nitrogen or solid CO2 into the body of the grinder. The method is esp. applied to rubber and to poly(vinyl chloride). The method can be used to add a variety of agents (plasticisers, stabilisers, antioxidants, pigments, etc.) to a range of polymers (esp. polyvinyl resins, polyolefins, epoxy resins, polyesters, polyamides, polyurethanes and rubbers) to achieve desired properties. Additives are used in small amts. and it is often difficult to disperse them thoroughly in polymers, esp. if they are liqs. or pastes, or if the heat of mixing leads to melting as, e.g., with lubricating waxes. The new method gives very homogeneous dispersions with no agglomeration.</p> |
