| 摘要 |
An additive for aqueous paper coating compositions is essentially a blend of a C14 to C22 hydrogen-saturated fatty acid, for example a commercial grade stearic acid containing palmitic acid and residual oleic acid, and a non-ionic dispersant, the blend being in solid particulate form at room temperature, and having a melting point below the boiling point of water. A coating composition may be made by heating an aqueous slurry of a binder, for example starch, to a temperature above the melting point of the blend, mixing the aqueous and other components to form an emulsion of the fatty acid in the aqueous phase and mixing the emulsion with an aqueous suspension of pigment, for example clay dispersed with tetrasodium pyrophosphate. Other pigments are mentioned. A specific composition comprises 100 parts pigment, 8 to 30 parts starch, 3% to 5% by weight of the starch of the additive, the non-ionic dispersant comprising from 3% to 40% of the additive. Other binders are protein or casein, and additionally from 1 to 5 parts latex may be added to the composition. The non-ionic dispersant may be condensates of ethylene oxide with fatty acids and with dihydric fatty alcohols, polypropylane glycol esters of hydroxy fatty acids, polyhydroxyalcohol esters of fatty acids, ethoxylated fatty acid-alkanolamine condensates, propylene glycol ethylene oxide condensates. |
