Use of organic additives as binders in raw mixtures for ceramic tiles

The aim of this work is the study of the role played by organic additives used as binders in raw mixtures for ceramic tiles. Such binders are extensively used for the production of advanced ceramic materials. In traditional ceramics, they can, in principle, allow for a drastic education of the clay fraction and consequently a very positive effect on the colour of the ceramic body without affecting its peculiar physical properties. Polyvinyl alcohol (PVA) was added in proportions of less than 0.5 wt% to different typical raw ceramic mixtures in which the weight fraction of clay minerals was reduced of about 50 wt%. In each case, it was possible to obtain very good mechanical properties of the green bodies. Clay minerals are the component of the mixture with the highest price and the highest content of iron and titanium (known to have negative effects on the whiteness of the ceramic body). Decreasing the amount of clay minerals makes possible to produce ceramic bodies with the same colour, using less quality (i.e. less expensive) raw materials. This can also lead to reconsider the use of several raw materials present on the national territory. Furthermore, superwhite ceramic bodies can easily be obtained even without the introduction of very expensive components such as zircon and alumina. Possible drawbacks appear to be not severe as the milling times are increased of less than 3% (in laboratory), and additional costs due to the organic additive are overwhelmed by the savings due to the choice of less expensive raw materials and the reduction of the clay fraction (up to 20%).