JPH0378691B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic recording medium, and particularly to a magnetic recording medium having excellent electromagnetic conversion characteristics, running properties, and durability. In magnetic recording media, particularly video cassette tapes, extremely high density recording has become possible by shortening the recording wavelength and narrowing the track width. Therefore, there is a demand for a tape with excellent electromagnetic conversion characteristics that has a high output and a high S/N ratio. In addition, while the total thickness has become thinner than 20 μm, with the spread of portable VTRs, the running durability of VTRs is even better than that of conventional VTRs.
Tape requested. For this reason, various additives have been proposed in the past, but at present it is difficult to find one that completely satisfies the above requirements. Esters of straight chain fatty acids obtained from animal and vegetable oils and monovalent aliphatic saturated alcohols have been often used as they are inexpensive and have relatively good runnability and durability. However, when these esters of straight chain fatty acids and monovalent aliphatic saturated alcohols are used, it has been insufficient to obtain the currently required running properties and durability. The first object of the present invention is to provide a novel magnetic recording medium. The second object is to provide a magnetic recording medium having excellent electromagnetic conversion characteristics. Third, it is an object of the present invention to provide a magnetic recording material having excellent runnability and durability. As a result of examining various additives, the present inventors found that particularly excellent running performance and durability can be obtained when using an ester of a branched saturated fatty acid and a monovalent aliphatic alcohol, leading to the present invention. It is ivy. That is, the present invention provides a magnetic recording body comprising a magnetic layer in which fine ferromagnetic powder is dispersed in a binder on a non-magnetic flexible support, the magnetic layer has a melting point of 20° C. or lower, a carbon number This magnetic recording material is characterized by containing a fatty acid ester obtained from a 12 or more branched saturated fatty acid and a monovalent aliphatic alcohol. The fatty acid ester obtained from a branched saturated fatty acid and a monovalent aliphatic alcohol used in the present invention refers to a branched fatty acid having 12 to 22 carbon atoms and a branched fatty acid having 1 to 18 carbon atoms.
More preferably, it is a fatty acid ester obtained from a branched fatty acid having 12 to 18 carbon atoms and a branched aliphatic alcohol having 3 to 18 carbon atoms. The branched saturated fatty acids used in the present invention are fatty acids having branched alkyl groups. These fatty acids are preferably ethylene, propylene, α-
It is synthesized from olefin, -carbon oxide, etc. by a conventionally known method such as the oxo method. Among natural fatty acids, there are branched saturated fatty acids such as isomyristic acid (12-methyltridecanoic acid) and isostearic acid (16-methylheptadecanoic acid), but both have high melting points and are not preferred. Examples of synthesized branched saturated fats are shown below. In addition to these, saturated fatty acids with various branches can be synthesized. The aliphatic saturated alcohols used in the present invention include methyl alcohol, ethyl alcohol, n-
Monohydric linear alcohols having 1 to 18 carbon atoms such as propyl alcohol, n-butyl alcohol, lauryl alcohol, stearyl alcohol, or isopropyl alcohol, isobutyl alcohol,
3-18 carbon atoms such as 2-ethylhexyl alcohol
It refers to monohydric branched alcohols, and branched alcohols are particularly preferred. The melting point of the branched fatty acid ester used in the present invention is about 0°C or less, preferably about -10°C or less, more preferably about -20°C or less. If the melting point is about 0° C. or higher, the durability of the obtained magnetic recording medium will be low, which is not preferable. The branched fatty acid ester used in the present invention is about 0.1 to 10 wt%, preferably 0.5 wt% based on the ferromagnetic powder.
~5wt% is added. If it is less than about 0.1%, no lubricating effect can be obtained, and if it is more than about 10 wt%, the amount added is too large and the lubricating effect is deteriorated, which is not preferable. The branched saturated fatty acid esters used in the present invention may be used alone or in a mixture of two or more. The branched saturated acid ester used in the present invention particularly improves running properties when used in combination with conventional fatty acids having 12 to 22 carbon atoms. As examples of fatty acids having 12 to 22 carbon atoms, lauric acid, silistic acid, parsitic acid, stearic acid and oleic acid are particularly preferred. Furthermore, it has been found that the use of an abrasive having a Mohs hardness of 6 or higher is particularly preferable because durability is improved without increasing head wear. Many examples of such abrasive materials are known, but
Among these, α-alumina having an average particle size of 1 μm or less is particularly preferred. Some specific examples of branched saturated fatty acid esters used in the present invention are shown below. The magnetic recording material of the present invention is manufactured by applying and drying a magnetic coating material containing a binder, ferromagnetic powder, the branched saturated fatty acid ester according to the present invention, and other additives dispersed together with an organic solvent onto a support. As the ferromagnetic powder, in addition to r-Fe ₂ O ₃ and Co-modified iron oxide, alloy fine powder mainly composed of iron is particularly preferable. For details on ferromagnetic powder, additives, organic solvents, dispersion, coating methods, etc., see JP-A-52-108804 and JP-A-54.
-21805, 54-46011, etc. EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention should not be limited to these Examples. In the examples, "parts" indicate "parts by weight." Example 1 γ-Fe ₂ O ₃ (Hc380Oe, acicular ratio 10:1, average particle length 0.4μ) 100 parts vinyl chloride/vinyl acetate/vinyl alcohol copolymer (93:2:5 wt% degree of polymerization approximately 400) 20 parts polyester polyurethane (molecular weight approximately 130,000) 5-part branched saturated fatty acid ester (the fatty acid used was
Shown in the table. ) 1 part oleic acid 2 parts methyl ethyl ketone 200 parts cyclohexanone 100 parts The above composition was kneaded and dispersed in a batch type sand grinder for 3 hours, and then filtered through a filter having an average pore size of 3 μm to obtain a magnetic paint. The resulting coating solution was applied onto a 7μ thick polyethylene terephthalate film using a reverse roll so that the dry thickness was 5μ, and the coating was applied while the coating layer was still wet.
Magnetic field alignment treatment was performed using a 1000 Gauss electromagnet and the material was dried. After drying, the magnetic layer was smoothed by super calender roll treatment. Slit this,
An audio cassette tape (phillip type compact cassette) with a width of 3.81 mm was obtained. The properties of the obtained audio tapes are shown in Table 1, Nos. 1 to 8. Comparative Example 1 Audio tapes C-1 and C-2 were obtained in the same manner as in Example except that a straight chain saturated fatty acid ester was used in place of the branched saturated fatty acid ester of Example 1 and the fatty acid ester was omitted. Ta. The results obtained are shown in Table 1. Example 2 Co-coated beltlide iron oxide (Co2.0 atomic% deposition, FeO1.4, Hc660Oe, ferrous ratio 10:1, average particle length 0.5μ) 100 parts Vinyl chloride/vinyl acetate/vinyl alcohol copolymer (95:5:5wt%, degree of polymerization approximately 400) 15 parts polyester polyurethane (molecular weight approximately 130,000) 10 parts branched saturated fatty acid ester (the fatty acid used was
(shown in the table) 2 parts oleic acid 2 parts α-alumina (average particle size 0.5μ) 3 parts methyl ethyl ketone 200 parts cyclohexanone 100 parts After kneading and dispersing the above composition for 3 hours in a batch type sand grinder, the polyisocyanate compound ( Coronate L-75 manufactured by Nippon Polyurethane KK)
6 to 7 parts (solid content: 5) were added and kneaded and dispersed for an additional 30 minutes. After kneading and dispersing, the mixture was passed through a filter having an average pore size of 1 μm to obtain a magnetic layer coating solution. The obtained magnetic paint was applied onto a polyethylene terephthalate film with a thickness of 14μ using a reverse roll so that the dry thickness was 5μ.
Magnetic field alignment treatment was performed using a Gaussian magnet and the material was dried. After drying, a super calender roll treatment was performed to smooth the magnetic layer. Slit this,
A 1/2 inch wide video cassette tape (VHS type video cassette) was obtained. The properties of the obtained videotapes are shown in Table 2 Nos. 9 to 16 below. Comparative Example 2 A videotape was obtained in the same manner as in Example 2, except that a conventional linear fatty acid ester was used in place of the branched saturated resin acid of Example 2, and the fatty acid ester was not used. The obtained results are shown in Table 2 Nos.C3 and 4. Example 3 Fe-Ni alloy fine powder (Fe:Zn=95:5,
A videotape was obtained in the same manner as in Example 2, except that Hc1300Oe, acicular ratio 10:1, average particle length 0.3μ) was used. The properties of the obtained video tapes are shown in Table 3, Nos. 17-19. Comparative Example 3 Fe-Zn alloy fine powder (Fe:Ni=95:5,
A videotape was obtained in the same manner as in Comparative Example 2 except that Hc1300Oe, acicular ratio 10:1, average particle length 0.3μ) was used. The properties of the videotapes obtained are shown in Table 3, Nos. C to 5.

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[Table] The methods for measuring the properties shown in Tables 1, 2, and 3 are shown below. (a) Maximum output level of 315Hz (distortion rate 3%) when MOL315 reference tape is 0dB (reference tape: Fuji Cassette ERC-90 manufactured by Fuji Photo Film KK, measuring device 582 type manufactured by Nakamichi KK) (b) SOL10K standard Saturation output level at 10KHz when the tape is set to 0dB (c) Audio runnability At 25℃ using 100 commercially available cassette decks
Running tests were conducted at 50% RH and 40°C and 80°C RH to evaluate the quality of the roll. A...No disordered winding. B...Uneven winding occurred on 1 to 5 decks. C...5 to 10 decks caused winding disorder. D... 11 or more decks caused winding disorder. (d) Tape squeal During the running performance test, the presence or absence of tape squeal was evaluated. A...There is no tape squeal at all. B...Temporary occurrence in volumes 1 and 2. C...Temporary occurrence in volumes 3 to 5. D...Temporary and constant squealing of 5 or more volumes 1-2
Volume occurs. (e) Staining After evaluating the runnability, the level of dirt on the deck head was evaluated. A: There is no dirt at all, and even if there is, it is difficult to check. B...There is some dirt, but it is not a problem. C...There is quite a lot of dirt. (f) Video output 4MHz output when the reference tape is set to 0 dB (reference tape: Fuji Photo Film KK VHS tape, measuring device: Matsushita Electric KK NV-6600 model). (g) S/N ratio S/N ratio of 10K to 4MHz with visual correction (measurement device: Matsushita Electric KK NV-6600 model). (h) Still life Time (minutes) until significant defects appear on the screen when playing back in still mode (Measuring device: NV-6600 model manufactured by Matsushita Electric KK). (i) Video running performance Commercially available video cassette deck (VHS type)
Using 50 units, 25℃50%RH and 40℃80%RH
A running test was conducted to evaluate jitter and skew. A... It's not like the jitters are too big or too skewed. B... Jitters or skews sometimes occur, but there are almost no problems. C... Jitter or skew occurs quite frequently and is a problem. (j) Dirt After evaluating the runnability, the level of dirt on the deck head was evaluated. A: There is no dirt at all, and even if there is, it is difficult to check. B...There is some dirt, but it is not a problem. C...There is quite a lot of dirt. As shown in Table 1, audio tapes No. 1 to 8 using the resin acid ester according to the present invention are as follows:
It can be seen that the MOL and SOL are higher than the conventional audio tape No. C1 that uses fatty acid ester and the tape that does not use fatty acid ester, and that it has excellent electromagnetic conversion characteristics. Furthermore, it can be seen that the fatty acid ester according to the present invention not only has excellent electromagnetic conversion properties but also has good running properties, does not cause tape squealing, and has little dirt. On the other hand, it can be seen that conventional resin acid esters cause tape squealing and are not very good in runnability or dirtiness. From Tables 2 and 3, videotape Nos. 9 to 19 using the fatty acid ester according to the present invention are videotape No. C5 using the conventional fatty acid ester,
It can be seen that the video output S/N ratio is higher than that of C-7, and the electromagnetic conversion characteristics are excellent. It can also be seen that Nos. 9 to 19 have a longer still life than Nos. C5 to 8, have good video running properties, generate less dirt, and have excellent running properties and durability. As described above, it has been found that by using the branched saturated fatty acid ester according to the present invention, it is possible to obtain magnetic recording properties that not only have excellent electromagnetic conversion characteristics but also have excellent running properties and durability.

Claims (1)

[Claims] 1. A magnetic recording material comprising a magnetic layer in which a magnetic fine powder is dispersed in a binder on a non-magnetic flexible support, wherein the magnetic layer contains a branched saturated fatty acid having 12 to 22 carbon atoms; A magnetic recording material characterized by containing a fatty acid ester obtained from a monovalent aliphatic alcohol having 1 to 18 carbon atoms.