Until the beginning of the 1900:th century the paper making process was handicraft. The paper machines that have been developed since then are as impressing in size as fascinating when it comes to the technique. The process has always been improved to give a better paper for lower costs, with as short manufacture time as possible. Stratified forming has been a reality since 1830. From the beginning it was applied to board and paperboard. Now it is also the most common method for making tissue and one paper mill in Austria use it for fine paper. Stratified forming can be categorized as separate forming or simultaneous forming. Separate forming means using several headboxes and sometimes even several wires. Simultaneous forming means using only one stratified headbox. This method has many advantages over separate forming, inter alia improved economy, quality, wood exchange and higher runability of the paper machine. Several experiments have been done with simultaneous forming of different fibres by placing a fibre with high bulk in the middle layer and a smooth fibre on the surface layers. The results has shown that by using this method both the bending stiffness and surface properties are improved, or a lower grammage paper is obtained with maintaining quality. Simultaneous forming can also be used to stratify fillers in layers where they are most efficient. In that way both paper quality and economy is improved. Simultaneous forming is also used for fractionated pulp. Fractionation means separating springwood fibre from summerwood fibre, and placing them in separate layers. Research results of fractionated pulp show about the same result as simultaneous forming of different fibres.

The structure and composition of denim jeans is complex. In addition to cotton, which is the dominating type of textile fibre, there may be up to about 20 % synthetic fibres. The synthetic fibres are found in the sewing thread and in the elastic yarns that are used to make stretch denim jeans. In total it was found that up to six different types of textile fibres may be present in the material. To be able to recycle cotton in jeans by producing regenerated cellulose fibres a very high purity with respect to cotton is required. The purpose with this project was to investigate the possibility to fractionate the textile material found in denim jeans to obtain a pure cotton fraction that can be used in the viscose process to produce regenerated cellulose fibres, which then can be used to manufacture new clothes. In this project traditional wet mechanical separation equipment found in the pulp and paper industry, in the form of a laboratory screen (used as a model for a pressure screen) and hydrocyclone, was used to fractionate the textile material from cut and shredded denim jeans. The degree of separation of synthetic fibres from cotton fibres was quantitatively evaluated by measuring the glucose content after acid hydrolysis. The results from the experimental work showed that there were runnability problems both regarding disintegration and fractionation. Regarding the fractionation, plugging was found to be a problem and no significant separation of synthetic fibres from cotton fibres was obtained with the conditions of the experiment. / Strukturen och sammansättningen i denimjeans är komplex. Utöver bomull, vilken är den dominerande typen av textilfiber, kan de innehålla upp till 20 % syntetiska fibrer i tyget. De syntetiska fibrerna finns i sytråden och i elastiska garner som används för att tillverka stretchdenimjeans. Den här studien visade att upp till sex olika typer av textilfibrer kan förekomma i materialet. För att kunna återvinna bomull i denimjeans genom att producera regenererade cellulosafibrer krävs en mycket hög renhet med avseende på bomull. Syftet med projektet var att undersöka möjligheten att fraktionera textilmaterialet i denimjeans för att erhålla en ren bomullsfraktion som kan användas i viskosprocessen för att tillverka regenererade textilfibrer, vilka sedan kan användas för att tillverka nya kläder. I projektet användes, inom massa och pappersindustrin traditionell våtmekanisk separationsutrustning i form av en laboratoriesil (här använd som en modell av en trycksil) och en hydrocyklon, för att fraktionera textilmaterialet från klippta och sönderslitna denimjeans. Separationsgraden av syntetiska fibrer från bomullsfibrer bestämdes kvantitativt genom att mäta glukoshalten efter sur hydrolys. Resultatet från det experimentella arbetet visade att det finns körbarhetsproblem både gällande uppslagning och fraktionering. För fraktioneringen visade sig pluggning vara ett problem och ingen signifikant separation av syntetiska fibrer från bomullsfibrer erhölls med förhållandena i experimentet.