Influence of the Reclaim Addition to the Moulding Sand Matrix Obtained in the ALPHASET Technology on the Emission of Gases - Comparison with Moulding Sand with Furfuryl Resin

This study focuses on the ALPHASET process of mould making (Ester-Cured Alkaline Phenolic No-Bake). The cross – linking of alkaline phenolic resole resin by adding at least one kind of organic esters is the secondary popular system (after the technology of molding sands with furfuryl resins) with the advantages including low odour, virtually no smoke, easy to stripping, good finishing, low veining, minimal erosion, and very good hot strength. The phenolic resoles used in the system are prepared typically by reacting 30-55% formaldehyde solution with less phenol using a strong alkali catalyst, such as sodium hydroxide or potassium hydroxide at the temperatures of below 110^oC (pH > 7). After removing parts of water this yields a thermal set phenolic resin solution with solid content 50-70%. In order to significantly increase strength and to improve the moisture and humidity resistance of sand mould, it is necessary to mix a little silence solution addition with resin binder (about 0.1 – 0.3% based on the amount of resin binder).