http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4255492-A
Outgoing Links
| Predicate | Object |
|---|---|
| assignee | http://rdf.ncbi.nlm.nih.gov/pubchem/patentassignee/MD5_5d9f3ca41550d315642580237250c5b0 |
| classificationCPCAdditional | http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/Y10S428-90 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C01P2004-10 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C01P2004-03 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C01P2004-54 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C01P2004-62 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C01P2006-42 |
| classificationCPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/G11B5-70652 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/G11B5-70647 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C01G49-06 |
| classificationIPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/C01G49-06 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G11B5-706 |
| filingDate | 1974-11-11-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| grantDate | 1981-03-10-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| inventor | http://rdf.ncbi.nlm.nih.gov/pubchem/patentinventor/MD5_8ee191b58b4d864a68c79ef3e4b0e547 http://rdf.ncbi.nlm.nih.gov/pubchem/patentinventor/MD5_cb87f1d9892b64ed005d0fecae17b001 |
| publicationDate | 1981-03-10-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationNumber | US-4255492-A |
| titleOfInvention | Magnetic recording crystals, process for producing same, and magnetic recording webs using same |
| abstract | A process for preparing acicular gamma ferric oxide (maghemite) crystals exhibiting excellent magnetic recording properties is disclosed. These acicular gamma ferric oxide crystals are new materials and can be used in magnetic media such as magnetic tapes to obtain a low level of white noise without sacrificing other electroacoustic properties. The crystals are basic in character, contain alkali metal ions and have an acicularity ratio of at least 15, often 15 to 40. These crystals are prepared under very carefully controlled reaction conditions, as more fully described in the following specification. In general, however, the process involves (1) reacting ferrous salt with a stoichiometric excess of an alkali hydroxide under non-oxidizing conditions and at a temperature below about 60 DEG C. while substantially avoiding local excesses of the ferrous salt, to form an aqueous dispersion of ferrous hydroxide particles, (2) introducing oxygen into the dispersion to convert the ferrous hydroxide particles to crystals of alpha ferric oxide hydrate, (3) discontinuing introduction of the oxygen into the dispersion, (4) boiling the dispersion to obtain further crystallization of the alpha ferric oxide hydrate crystals and subjecting the crystals to dehydration, reduction and oxidation to form gamma ferric oxide crystals. As indicated in the specification, failure to observe the reaction conditions set out in the specification and claims deleteriously affects the magnetic recording properties of the gamma ferric oxide crystals. Additional doping ions such as alkaline earth metal ions and/or other ions of metals such as cobalt, nickel, chromium, zinc, manganese or calcium can be introduced into the gamma ferric oxide crystals during their preparation to further improve properties for magnetic recording. Products which are useful in magnetic recording such as magnetic tapes, discs, drums and striped motion picture film containing the acicular gamma ferric oxide crystals are disclosed. |
| isCitedBy | http://rdf.ncbi.nlm.nih.gov/pubchem/patent/WO-8200287-A1 http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4975324-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4382982-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4956220-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4359453-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4515857-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4876022-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-2005039687-A1 http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-5487954-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4731239-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/AU-614897-B2 http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-6179987-B1 http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-7828899-B2 http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-2002136693-A1 http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-5069216-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-4342589-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-5219554-A http://rdf.ncbi.nlm.nih.gov/pubchem/patent/US-5641470-A |
| priorityDate | 1969-09-25-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| type | http://data.epo.org/linked-data/def/patent/Publication |
Incoming Links
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