| 摘要 |
<p>1466292 Epoxy resin dispersions DOW CHEMICAL CO 21 May 1974 [23 May 1973] 22660/74 Heading C3B An aqueous dispersion comprises: (A) 2-75 parts by wt. of a water-insoluble epoxy resin having an average particle size <10 Á, provided that when the average is > 5 Á, not more than 25% by wt. of the particles have an average size >15 Á; (B) 98-25 parts by wt. of water; and (C) 1-10 parts by wt. of epoxy resin of a non-ionic dispersing agent which is a synthetic gum derived from cellulose, a hydroxyalkyl guar gum or a polyvinyl alcohol containing unhydrolysed acetate groups. (A) may be a solid diglycidyl ether of bisphenol A or an epoxy novolac resin. The dispersion may be prepared by: (1) mixing in a high shear mixer, a first stream containing water and a dispersing agent, as set out above, with a seconding stream containing water insoluble epoxy resin liquefied by heating or dissolved in an organic solvent; (2) circulating the resultant streams through a high shear mixer until the concentration of solid dispersed epoxy resin reaches the desired level; and (3) separating the organic solvent, when present, therefrom. In an alternative method: (1) water, a dispersing agent as defined above and the solid epoxy resin are mixed at a temperature such that a highly viscous homogeneous mixture is obtained; (2) the mixture is maintained at such a temperature for 30 minutes to 12 hours; and (3) water is slowly added until the desired solids level is obtained. Uses.-Coating compositions.</p> |
