| 摘要 |
518,429. Filtering - media. NAAMLOOZE VENNOOTSCHAP MAATSCHAPPIJ TOT BEHEER EN EXPLOITATIE VAN OCTROOIEN. Aug. 25, 1938, No. 25024. Convention date, Aug. 25, 1937. [Class 46] [Also in Groups VIII and III] A fibrous product, for use as a filter, having a base of artificial silicate fibres, e.g., glass, is obtained by coating the fibres with an organic bonding agent and converting the bonding agent into substantially pure carbon by heating the coated fibre mass in the absence of oxygen. Specified bonding agents include carbohydrates, starches, oils, waxes and resins. Coating of the fibre may be effected by spraying, soaking or mechanical mixing. Carbonization may be effected in a closed chamber, or as a continuous process with exclusion of oxygen, at a temperature of 300-350‹C. The carbonizing temperature may be lowered by addition of small quantities of lime or alum. Oxalic acid, boric acid, chrome alum, tannic acid, lead acetate, copper acetate and urea give tougher bonds with starch. For filter diaphragms the porosity may be regulated by addition of a small quantity of inert material, e.g., clay or bentonite. The Specification as open to inspection under Sect. 91 describes also the use as bonding agents of aqueous dispersions of phenol-formaldehyde resins, powdered soft coal and metallic wax such as calcium stearate. This subject matter does not appear in the Specification as accepted.
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