| 摘要 |
An aqueous emulsion, e.g. for sizing paper, comprises as the continuous phase, an aqueous solution of a catonic amine modified starch having the formula: <FORM:0903416/V/1> p wherein x is starch, R1 is an alkylene, hydroxyalkylene, phenyl alkylene or alkylalkylene radical, and R2 and R3 are each a hydrogen atom, or an alkyl, aryl, aralkyl or cycloalkyl radical, and, as the dispersed phase, a higher ketene dimer or a mixture of higher ketene dimers having the formula: [RCH=C=O]2 wherein R is an alkyl radical having at least 8 carbon atoms, a cycloalkyl radical having at least 6 carbon atoms, or an aryl, aralkyl or alkaryl radical. Based on the weight of the emulsion, the preferred concentration of the modified starch is from 0,5% to 6% and of the ketene dimer from 1 to 15%, the ratio of ketene dimer to modified starch being preferably from 20 : 1 to 1 : 100. Suitable cationic amine-modified starches are disclosed in Specifications 765,880 and 854,161 and the preparation of suitably-modified starches by etherifying ungelatinized starch or starch derivatives is also described. Suitable higher ketene dimers are specified. The emulsions are prepared by vigorously mixing the two constituents together with water and, if desired, a pentachlorphenate, e.g. in a colloid mill or homogeniser, the starch being preferably previously cooked at 90 to 95 DEG C. in water. |
