| 摘要 |
<p>The invention concerns a process for producing aqueous dispersions for subsequent processing to electro-dipcoat enamels with stoving temperatures less than 160°C and stoving times less than or equal to 30 minutes. These dispersions contain binders in the form of modified epoxide and amine adducts and crosslinking agents in the form of polyisocyanates blocked with amino groups. In this process, polyepoxides and compounds containing one or more, preferably two, hydroxyl groups per molecule are converted at high temperatures by catalysis to epoxide-containing intermediate products. A solvent or solvent mixture is added under external cooling and a solution is boiled under reflux, if necessary under vacuum, until the temperature is reduced to between 95°C and 20°C. Amines are then added to the free epoxide groups still present in the epoxy resin and a dispersion is produced after addition of the crosslinking agent by addition of a water-acid mixture or a dispersion is first produced and a crosslinking agent then added.</p> |
