| 摘要 |
<p>PVC obtd. by aqs. emulsion polymerisation contains a thermal stabiliser and/or lubricant. It is dried by atomisation of the dispersion into powder to give >90 wt.% particles >63 microns and 50 wt.% particles >160 microns. The thermal stabiliser and/or lubricant, which are not miscible in the dispersion, are atomised in the liq. state during atomisation of the PVC dispersion by means of double feed inlets functioning separately. 0.02-2 Wt.% w.r.t. PVC, of stabiliser and/or lubricant are pref. used. 1.6-200 Kg air/kg of liq. are used for atomisation. 2-4 double inlets are used for a capacity of up to 4 tonnes PVC/hr., and 4-10 for 4-8 tonnes/hr. Used as stabilisers and/or lubricants are used to render PVC suitable for extrusion or calendering. When the stabiliser and/or lubricant additives are not miscible with the PVC dispersion, phase sepn. after additive addn. causes heterogeneous mixts., which give non-homogeneous atomised powders. The additives hence cannot exert their full effect. Also, blockages of the atomisation inlets constantly occur. This causes frequent interruptions, and lack of control of drying tower temps. These problems are avoided by the present method.</p> |
