| 摘要 |
The starch has a Brookfield viscosity of 100 to 20000mPa.s, preferably 250 to 18000mPa.s or even 500 to 15000mPa.s and an aqueous solubility of 10 to 85%, preferably 10 to 80% or even 12 to 80%. The starch is modified by subjecting it to at least one chemical or physical treatment, in particular it is reticulated, extruded and/or treated in a drying drum. The industrial fluid has a pH above 8.5, preferably between 8.5 and 12, even better between 9 and 11.5, and is used at a temperature above 130 deg.C, preferably 135 deg.C or even 140 deg.C in particular for drilling. An independent claim is included for a process for preparing a modified leguminous starch which can be used as a component of an industrial fluid, by subjecting the leguminous starch to at least one chemical or physical treatment so the resulting starch can be used as described above. In particular, the starch is subjected to a treatment other than extrusion, specifically to a treatment in a drying drum. The chemically modified starch, in particular reticulated, is extruded. Specifically, the vegetable starch which can be used as described above or which is prepared as described above has a Brookfield viscosity of between 2000 and 8000 mPa.s and an aqueous solubility of between 15 and 50%, or a Brookfield viscosity of between 500 and 1900 mPa.s and an aqueous solubility of between 30 and 80%. |
