摘要:
A process for the manufacture of acicular ferromagnetic metal pigments containing iron, having a reduced field strength distribution and a steeper residual magnetization curve, by applying an alkaline earth metal cation and an organic compound having at least one group capable of forming a chelate to appropriate acicular iron oxides and then reducing the treated oxides.
摘要:
A process for the manufacture of acicular gamma-iron(III) oxide, in which the non-magnetic, acicular iron(III) oxide is treated with a solution of a compound of the formula I ##STR1## where R.sup.1 and R.sup.2 are ##STR2## or O--R.sup.5, R.sup.3 is H, OH, ##STR3## or O--R.sup.5, R.sup.4 is alkyl or cycloalkyl of 1 to 16 carbon atoms and the R.sup.4 's may be identical or different, and R.sup.5 is alkyl, cycloalkyl or aralkyl of 3 to 18 carbon atoms, and is then converted to gamma-iron(III) oxide by reduction to magnetite, followed by oxidation.The gamma-iron(III) oxide obtained is distinguished by a high coercive force and improved magnetic orientation when used as a magnetic pigment for the manufacture of magnetic recording media.
摘要:
A process for the manufacture of acicular magnetic gamma-iron(III) oxide by reducing acicular alpha-iron(III) oxide to magnetite and then oxidizing it to gamma-iron(III) oxide, wherein the alpha-iron(III) oxide is treated with a water-soluble alkaline earth metal compound and an alkylphenol with one to three alkyl radicals, each of 4 to 24 carbon atoms, on the benzene nucleus. Gamma-iron(III) oxides manufactured in this way show better magnetic orientability in the binder-containing dispersion, and a higher coercive force than prior art magnetic pigments.
摘要:
Goethite is obtained by reacting an aqueous solution of an iron (II) salt with an aqueous solution of an alkali metal hydroxide and oxidizing the resulting iron(II) hydroxide. The oxidation is carried out in three stages. In the first stage, from 4 to 15% by weight are oxidized in the course of from 0.4 to 5 hours, in the second stage from 60 to 85% by weight are oxidized in the course of from 1.5 to 6 hours and in a third stage the remaining amount of iron is oxidized.
摘要:
To isolate ammonia from gas mixtures containing ammonia and carbon dioxide, the gas mixture is first partially absorbed in a solvent, with residence times of at most 0.1 second, and the non-absorbed gas is then separated from the solution obtained. The solution is then subjected to a first desorption stage, in which only the ammonia present in an excess over a molar ratio of 3 parts of ammonia to 1 part of carbon dioxide is expelled by heating, and the entrained carbon dioxide is washed out of the expelled ammonia by means of solutions containing free ammonia. The solution remaining after the first desorption stage is substantially freed from ammonia and carbon dioxide in a second desorption stage and the expelled gas, containing solvent, together with fresh gas mixture is fed to the adsorption stage, while the solvent obtained from the second desorption stage is employed for the absorption.
摘要:
A process for the manufacture of acicular gamma-iron(III) oxide which, because of its improved dispersibility in organic binders, is suitable for the manufacture of magnetic recording media exhibiting a particularly high orientation ratio. For this purpose, the non-magnetic acicular .alpha.-iron(III) oxide or goethite pigment is treated with from 0.5 to 10% by weight, based on the pigment, of a compound of the formula I: ##STR1## where R.sup.1, R.sup.2 and R.sup.3 are hydrogen, alkyl of 1 to 24 carbon atoms or alkenyl of 1 to 24 carbon atoms and (RX).sup.- is selected from the group consisting of an aliphatic carboxylic acid of 1 to 18 carbon atoms, an aromatic carboxylic acid of 1 to 18 carbon atoms, a sulfonic acid and an ester of phosphoric acid and is then further processed by conventional methods to give gamma-iron(III) oxide.
摘要翻译:用于制造针状γ-氧化铁(III)的方法,其由于其在有机粘合剂中的分散性的改善而适用于制造表现出特别高取向比的磁记录介质。 为此,非磁性针状α-铁(III)氧化物或针铁矿颜料以基于颜料的0.5至10重量%的式I化合物处理:其中 R 1,R 2和R 3是氢,1至24个碳原子的烷基或1至24个碳原子的链烯基和(RX) - 选自1至18个碳原子的脂族羧酸,芳族羧酸 1至18个碳原子,磺酸和磷酸酯,然后通过常规方法进一步加工,得到γ-铁(III)氧化物。