PROCESS FOR THE PREPARATION OF ACICULAR A-FEOOH FOR MAGNETIC RECORDING MATERIAL

摘要

P PROCESS FOR THE PREPARATION OF A-FEOOH BY PARTIAL NEUTRALIZATION, THEN OXIDATION OF A FERROUS SALT SOLUTION IN THE PRESENCE OF PHOSPHORIC ACID TO FORM A-FEOOH SEED CRYSTALS, AND OPTIONALLY, BY ADDITIONAL OXIDATION OF THE SOLUTION WHILE NEUTRALIZING IT WITH AN ALKALINE SUBSTANCE FOR GROWING SUCH SEEDING CRYSTALS, IN WHICH PYROPHOSPHORIC ACID OR A SALT OF THIS ACID IS USED AS A PHOSPHORIC ACID AND THE SEEDING CRYSTALS OF A-FEOOH SHAPED AT A TEMPERATURE OF 50 TO 100C. THE A-FEOOH OBTAINED ACCORDING TO THE PROCESS OF THE PRESENT INVENTION CONSISTS OF FINE PARTICLES AND HAS A SIGNIFICANTLY IMPROVED ACICULARITY AND DISTRIBUTION OF PARTICULAR DIMENSION. A MAGNETIC RECORDING MEDIUM USUALLY MANUFACTURED FROM DERIVATIVE MAGNETIC IRON OXIDES, HAS A LOW NOISE CHARACTERISTIC AND EXCELLENT COERCIVITY AND OTHER EXCELLENT MAGNETIC PROPERTIES. /P