| 摘要 |
<p>The invention relates to the production of washing powders of stabilized or enhanced appearance which contain a fluorescent whitening agent of the formula <IMAGE> wherein X1 is hydrogen, chlorine, bromine, alkyl or alkoxy, X2 is hydrogen or alkyl and M is hydrogen, an alkali metal or ammonium ion. The stabilizing or enhancement of the appearance is effected by first dissolving or dispersing the fluorescent whitening agent in a mixture of water and a polyvinyl alcohol or polyvinyl pyrrolidone which is soluble or is able to swell in water, adding this solution or dispersion to the washing powder slurry and drying the slurry. The solution or dispersion can also be subsequently sprayed onto the dried residual washing powder. The appearance can be further enhanced by employing a polyethylene glycol, a surfactant containing ethyleneoxy and/or propyleneoxy groups, and/or a cellulose ether, in addition to the polymer in the solution or dispersion. The solution or dispersion comprising fluorescent whitening agent and polymer can also alternatively be dried, preferably by spray drying, to produce a preparation which, after it has been suspended in water, can also be added to the washing powder slurry. The slurry is then dried, preferably by spray drying.</p> |
