| 摘要 |
1331816 Benzyl starch PENICK & FORD Ltd 19 April 1971 [26 Jan 1970] 20343/71 Heading C3U [Also in Division B1] A bubble coating composition for paper, paper board and boxboard comprises an oil-in-water emulsion of which the aqueous phase contains, as a combination binder and emulsifier, benzyl starch containing 2 to 20% by weight of etherlinked benzyl groups. The emulsion typically contains 5-40% by weight of starch particles based on the weight of water, the weight ratio of oil to water is between 0À1 : 1 and 1À0 : 1, and the ratio of oil to benzyl starch between 0À1 : 1 and 10 : 1. The particles of starch and oil have average sizes less than 2 microns and less than 10 microns, respectively. The paper &c. is coated with the composition and the coating is dried at a temperature in the range 150-350‹ F. whereby the water and/or oil is/are removed. However, it is preferred that the oil be less volatile than water. The term " oil " covers hydrocarbon oil such as kerosene, fuel oils, mineral spirits, Stoddard's solvent and low melting fat or wax. The coating composition may include pigments such as clays and titanium dioxide imparting brightness and opacity. The starch is etherified in granular form with benzyl chloride in the presence of alkali and a swelling inhibitor such as sodium sulphate or sodium chloride. The resulting benzyl starch is dispersed by fragmentation or cooking, e.g. in a steam cooker. The degree of dispersibility can be enhanced by incorporating a small amount of alkali in the starch slurry while it is being cooked. High starch concentrations can be achieved through lowering the viscosity by acid hydrolysis or oxidative conversion with ammonium persulphate. |
