Melaminharze für die Papierindustrie 1996 : Grundlagen und Anwendung

About 50 years ago the application of melamine resins as paper additives has been mentioned for the first time. However, most of the development on this type of resins, carried out over the last 10 years, has been triggered by the customers which became more and more interested in the aspect of working hygiene. These efforts resulted in new products with higher performance or strongly reduced formaldehyde content. Different types of wet strength resins available on the basis of melamine resins will be presented. The suitability of the different resins to each of the different application fields will be discussed in more detail. The resin parameters, which have an impact on the crosslinking performance such as beating degree, pH, curing and the like will be outlined. Resin dosage, addition mode, sequence of addition and interactions with other additives will be further topics of the presentation. Wet strength may be achieved by either adding the melamine resin to the paper stock or impregnating the paper with the resin by using a size press. Both of these basic possibilities will be compared. Their impact on paper quality, costs, recycling, working hygiene and waste water is discussed. Using examples, the influence of formaldehyde reduction of the resins will be presented in the same way. Our conclusion is that there does not exist the melamine resin as such for the paper industry. In cooperation with paper- and resin-specialists the optimum solution has to be worked out for every particular application. Sometimes taylor made resins have to be furnished in order to cope with the requirements of our costumers.