| 摘要 |
<p>Binders, which when mixed with sand form sand cores and moulds for foundry use, (see Group XXII) comprise a mixture of unconjugated drying and semi-drying oils together with isano oil, preferably in an amount of 10-25%, which mixture is heat-bodied above 180 DEG C., most preferably at 230 DEG -270 DEG C., to a viscosity above 3000 cps. at 20 DEG C.; in a modification the unconjugated oils are first heat-bodied and then mixed with the isano oil. Suitable unconjugated oils are linseed, soyabean, perilla, grapeseed, sunflower seed, safflower seed, stillingia, tobacco seed or walnut oils; fish oils having an iodine number not below 160, unsaponifiable content not above 10% and saturated fatty acid content not above 10% may also be used. The oils to be used may if desired be modified by bodying, by addition of maleic anhydride, by blowing with air, or by interesterification with polyhydric alcohols other than glycerol such as pentaerythritol, and in addition esters obtained by esterifying fatty acids with a polyhydric alcohol having more than three hydroxyl groups such as pentaerythritol may be included. Up to 10% of such additives as driers, tall oil pitch, aromatic petroleum hydrocarbons, and unsaturated hydrocarbon resins may also be incorporated. Specifications 653,530, 761,035, U.S.A. Specification 2,817,886 and Swiss Specification 311,874 are referred to.</p> |
