Compositions: coating or plastic – Coating or plastic compositions – Sound recording
Patent
1980-02-04
1982-09-14
Morris, Theodore
Compositions: coating or plastic
Coating or plastic compositions
Sound recording
252 6256, 428329, 428900, 428694, 523174, B32B 1504, C09K 300
Patent
active
043493858
ABSTRACT:
The invention relates to a method of manufacturing an improved pigment of FeOOH particles. The starting material is an acidic or alkaline aqueous dispersion of FeOOH particles which has been manufactured according to known methods. According to the invention, a water-soluble ammonium salt, which is derived from a low-molecular weight, weakly acidic organic acid and which volatilizes either as such or after decomposition not greater than 450.degree. C., is added to the aqueous dispersion. As a result of the addition of the ammonium salt, the FeOOH pigment flocculates. It is then separated and washed with water which preferably is also provided with the ammonium salt. According to a further embodiment of the invention the resulting pigment which, after drying, has a very low salt content, is converted into an Fe pigment or a .gamma. Fe.sub.2 O.sub.3 pigment which also has a very low salt content. A magnetic recording element which is based on the Fe or .gamma. -Fe.sub.2 O.sub.3 pigment obtained according to the invention has improved life properties in particular when used or stored in a humid environment.
REFERENCES:
patent: 3382174 (1968-05-01), Hund
patent: 4140539 (1979-02-01), Hund et al.
patent: 4178416 (1979-12-01), Hector et al.
Offenlegungsschrift 25 08 932, Sep. 1979, Hund.
Offenlegungsschrift 21 62 716, Jun. 1973, Leitner et al.
"Purification of Iron Oxide [Fe.sub.2 O.sub.3 ]," Mitani et al., Chem. Abstr., vol. 82, 1975, p. 615, Abstract No. 148826n.
Groen Harm Jan
Huisman Hendrikus F.
Morris Theodore
Schechter Marc D.
U.S. Philips Corporation
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