Improvements relating to the bonding of sand for the making of cores and moulds

摘要

A core binder contains at least 5% of an acetylenic oil such as Boleko or Isano oil from the Ongokea nut, tariric acid oil from Picramnia Tariri or xymenynic acid from Ximenis Caffra, or oils containing acids of the stearolic series. Accelerators and/or driers may be added such as salts (e.g. naphthenates) of cobalt, manganese and lead or dithiocarbamates, zanthates or sulphides of thiourea, e.g. zinc diethyl dithiocarbamate. Sulphur or sulphur compounds or aniline may also be added. The ethelynic oils may be stand oils and may be processed by heating or blowing, isomerized p or vulcanized. The acetylenic oil is not heated prior to the core being baked. Other resins and oils, such as ethylenic oils may be added, and include linseed, tall, oiticica, colza, perilla or tung oil or rosin (and esters or salts thereof), petroleum pitches or resins, coal resin, or fish or animal oils. Solvents such as paraffin, white spirit, naphtha, xylene, toluene or shale oil may be added or water-containing cellulose esters, gelatinized starch, dextrine, sulphite lye and clays. Molasses may also be included. The cores may be baked in a stove in which the hot air and flue gases are continuously recirculated.