tertiary ammonium fatty acid salts, tertiary ammonium fatty acid salt compositions, magnetic recording medium lubricants, and magnetic recording media

Abstract

To provide a lubricant capable of improving the frictional properties of a magnetic recording medium, and to provide a magnetic recording medium with excellent frictional properties when such a lubricant is applied. [Solution] A lubricant for magnetic recording media comprising a tertiary ammonium fatty acid salt represented by the following formula (1), and at least one of the tertiary ammonium fatty acid salts. TIFF2026144057000007.tif33146 (In formula (1), R represents an alkyl group having 18 or more carbon atoms, R1 represents an alkyl group having 10 or more carbon atoms, and R2 and R3 each represent alkyl groups. However, the number of carbon atoms in R2 and R3 is less than or equal to the number of carbon atoms in R1, and (the number of carbon atoms in R + 1) is different from the number of carbon atoms in R1 to R3.)

Description

[Technical Field]

[0001] The present invention relates to tertiary ammonium salts of fatty acids, tertiary ammonium salt compositions of fatty acids, lubricants for magnetic recording media, and magnetic recording media. [Background technology]

[0002] In magnetic recording systems that use magnetic tape, such as LTO (Linear Open Tape), lubricants are added to the magnetic recording medium to improve the coefficient of friction between the magnetic head and the magnetic tape and to enhance durability. In most magnetic tapes, mixtures of long-chain hydrocarbon fatty acids and their esters have been used as lubricants (Non-Patent Literature 1: NIKKEI MATERIALS & TECHNOLOGY Special Issue "Practical Encyclopedia of Materials" pp. 116-131). It is also known that fatty acid salts are used as lubricants for magnetic recording media. Patent Literature 1 (JP-A-4-271012) discloses the use of a tertiary ammonium salt of a long-chain fatty acid as a lubricant for a coated magnetic recording medium. In the example of Patent Literature 1, a dimethylstearylammonium salt of stearic acid is synthesized, and a composition obtained by mixing it with a magnetic material, resin component, and solvent is applied to a tape substrate to create a magnetic layer containing the lubricant.

[0003] Patent document 2 (Japanese Patent Publication No. 4-370520) discloses a long-chain fatty acid quaternary ammonium salt as a lubricant for magnetic recording media. In the example of Patent document 2, a magnetic tape is fabricated by coating the surface of a ferromagnetic metal thin film with a thickness of 200 nm with a long-chain fatty acid quaternary ammonium salt having 12 to 18 carbon atoms.

[0004] Patent Document 3 (Japanese Patent Publication No. 4-372718) describes long-chain fatty acid ammonium salts (RCOO - HN +The invention discloses the use of R1, R2, and R3 as lubricants for coated magnetic recording media. At least one of R, R1, R2, and R3 is a hydrocarbon having 10 or more carbon atoms, or a hydrocarbon containing a halogen. In the examples of Patent Document 3, magnetic tapes are made to which dimethylstearylamine salt of stearic acid, primary amine salts and secondary amine salts of stearic acid are added. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-271012 [Patent Document 2] Japanese Patent Application Publication No. 4-370520 [Patent Document 3] Japanese Patent Application Publication No. 4-372718 [Non-patent literature]

[0006] [Non-Patent Document 1] NIKKEI MATERIALS & TECHNOLOGY Special Issue "Practical Encyclopedia of Materials", Nikkei BP Corporation, August 1994, pp. 116-131 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, the thinning of magnetic layers and the smoothing of tape surfaces have led to increased friction between magnetic heads and magnetic tapes. Therefore, there is a need for lubricants that can improve the coefficient of friction between the magnetic head and magnetic recording media, thereby enhancing the durability of the magnetic recording media. One of the objectives of this invention is to provide a lubricant that can improve the frictional properties and durability of magnetic recording media, and to provide a magnetic recording media with excellent frictional properties when treated with such a lubricant. [Means for solving the problem]

[0008] The present disclosure relates to a fatty acid tertiary ammonium salt represented by the following formula (1).

Chemical Formula

Effects of the Invention

[0009] According to the fatty acid tertiary ammonium salt according to the present disclosure and the lubricant containing the fatty acid tertiary ammonium salt, a lubricant is provided in which crystallization of the lubricant hardly occurs, which can improve the friction characteristics of a magnetic recording medium and improve the durability thereof. Further, a magnetic recording medium provided with such a lubricant and having excellent friction characteristics is provided.

Brief Description of Drawings

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of the magnetic recording medium according to the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view showing one embodiment of the magnetic recording medium according to the present disclosure. [Figure 3] FIG. 3 is a schematic diagram showing an apparatus for measuring high-speed friction characteristics. [Figure 4] FIG. 4 is micrographs of the surfaces of magnetic tapes of Example 4 and Comparative Example 1.

Mode for Carrying Out the Invention

[0011] [Summary of Embodiment] Embodiments according to the present disclosure will first be listed and described. Note that in this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less". Embodiments combining different technical means are also included in the technical scope of the present invention.

[0012] The present disclosure relates to a tertiary ammonium fatty acid salt represented by the following formula (1).

Chemical Formula

[0013] Conventionally, it is known to use organic ammonium salts of fatty acids as lubricants for magnetic recording media. On the other hand, in connection with the thinning of magnetic layers and the smoothing of tape surfaces, friction between a magnetic head and a magnetic tape tends to increase. For this reason, conventional fatty acid salt-based lubricants have insufficient lubrication performance, and magnetic tapes coated with these lubricants on the surface sometimes have insufficient practical properties, such as a reduction in the level of reproduction output in a tape running test, for example. In contrast, the fatty acid salt according to the present disclosure is a salt of a long-chain fatty acid and a tertiary amine having a carbon chain within a specific range, and is characterized in that the number of carbon atoms of the fatty acid and the number of carbon atoms of the alkyl group of the amine are different from each other. According to this compound, crystallization on the tape surface is less likely to occur, the friction coefficient of the magnetic tape can be reduced compared to conventional techniques, and the durability of the magnetic tape can be improved. Without being bound by theory, according to the compound of the present disclosure, sufficient lubrication performance is exhibited by the balance of the alkyl groups present in the fatty acid and the amine, and crystallization of the lubricant on the magnetic tape is suppressed. It is considered that the compound according to the present disclosure also maintains the affinity between the magnetic layer and the lubricant, resulting in a low friction coefficient.

[0014] In formula (1) above, R may be an alkyl group having 18 to 23 carbon atoms, and R1 may be an alkyl group having 10 to 24 carbon atoms. When within this range, the effects of this disclosure are clearer.

[0015] In formula (1) above, R2 and R3 may each be alkyl groups having 12 or fewer carbon atoms. Also, in formula (1) above, R, R1, R2, and R3 may each be linear alkyl groups. Furthermore, in formula (1) above, the difference between (number of carbon atoms in R + 1) and the number of carbon atoms in R1 may be between 1 and 12. When these ranges are met, the effects of this disclosure become clearer.

[0016] The fatty acid tertiary ammonium salt composition according to this disclosure comprises at least one of the fatty acid tertiary ammonium salts described in any of the above.

[0017] The lubricant for magnetic recording media according to this disclosure comprises at least one of the tertiary ammonium salts of fatty acids described in any of the above.

[0018] The magnetic recording medium according to this disclosure comprises a non-magnetic support and a magnetic layer laminated on the non-magnetic support, and includes a lubricant for the magnetic recording medium.

[0019] The magnetic recording medium may have a magnetic layer that contains a lubricant for the magnetic recording medium.

[0020] The magnetic recording medium comprises a lubricant layer laminated on the magnetic layer, and the lubricant layer may contain a lubricant for the magnetic recording medium.

[0021] [Specific examples of embodiments] The compounds, lubricants, and magnetic recording media related to this disclosure will be described in more detail below. [Tertiary ammonium salts of fatty acids] The fatty acid tertiary ammonium salt represented by formula (1) is a salt formed from a long-chain fatty acid and a tertiary ammonium compound. [ka] (In formula (1), R represents an alkyl group having 18 or more carbon atoms, R1 represents an alkyl group having 10 or more carbon atoms, and R2 and R3 each represent alkyl groups. However, the number of carbon atoms in R2 and R3 is less than or equal to the number of carbon atoms in R1, and (the number of carbon atoms in R + 1) is different from the number of carbon atoms in R1 to R3.)

[0022] In formula (1), R is an alkyl group having 18 or more carbon atoms and does not have an unsaturated bond. R may be a linear alkyl group or a branched alkyl group, but it is preferably a linear alkyl group. From the viewpoint of frictional properties, it is preferable that the number of carbon atoms in R is between 18 and 23. (Number of carbon atoms in R + 1) can be rephrased as the number of carbon atoms in the fatty acid. Specifically, examples of R include linear alkyl groups such as octadecyl group, nonadecyl group, eicosyl group, heneicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, and hexacosyl group, and branched alkyl groups such as 2-methylheptadecyl group, 2,3-dimethylheptadecyl group, 3-ethylnonadecyl group, 4-ethylnonadecyl group, 6-ethyleicosyl group, 5-propyleicosyl group, 7-methyldocosyl group, 9,10-dimethyldocosyl group, and 11-ethyldocosyl group. Among these, octadecyl group, nonadecyl group, eicosyl group, heneicosyl group, and docosyl group are preferred.

[0023] In other words, the fatty acids constituting the tertiary ammonium fatty acid salt according to this disclosure may be one or more selected from saturated fatty acids such as arachidic acid, behenic acid, tetracosanoic acid, pentacosanoic acid, hexacosanoic acid, heptacosanoic acid, and octacosanoic acid. Among these, arachidic acid, behenic acid, and tetracosanoic acid are preferred. Although fatty acids are generally compositions of several types of fatty acids, in this case, the fatty acids constituting the tertiary ammonium fatty acid salt according to this disclosure are composed mainly of fatty acids with 19 or more carbon atoms. Here, "the main component is a fatty acid with 19 or more carbon atoms" means that among the fatty acids constituting the fatty acid composition, the fatty acid with the highest content is a fatty acid with 19 or more carbon atoms.

[0024] In formula (1), R1 is an alkyl group having 10 or more carbon atoms, and R2 and R3 are alkyl groups. R1, R2, and R3 may be the same or different from each other. The number of carbon atoms in R2 and R3 is either the same as the number of carbon atoms in R1 or less than the number of carbon atoms in R1. That is, of R1, R2, and R3, R1 is the longest alkyl group, and R2 and R3 are alkyl groups that are the same length as or shorter than R1.

[0025] R1 is preferably an alkyl group having 10 to 24 carbon atoms, and more preferably 13 to 24 carbon atoms. R1 may be a linear alkyl group or a branched alkyl group, but it is preferably a linear alkyl group. Specific examples of linear alkyl groups for R1 include decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, heneicosyl group, docosyl group, tricosyl group, and tetracosyl group. Examples of branched alkyl groups R1 include isodecyl group, 2,3-dimethylnonyl group, 2-methylheptadecyl group, 2,3-dimethylheptadecyl group, 3-ethylnonadecyl group, 4-ethylnonadecyl group, 6-ethyleicosyl group, 5-propyleicosyl group, 7-methyldocosyl group, 9,10-dimethyldocosyl group, and 11-ethyldocosyl group. Of these, R1 is preferably a dodecyl group, a hexadecyl group, or an octadecyl group.

[0026] The fatty acid tertiary ammonium salts according to this disclosure are characterized in that, in the above formula (1), (number of carbon atoms in R + 1) and the number of carbon atoms in each of R1 to R3 are different. That is, the number of carbon atoms in the fatty acid (number of carbon atoms in R + 1) and the number of carbon atoms in the alkyl chain of the amine (R1 to R3) are different from each other. While it is not limited which of the two is larger, the number of carbon atoms in the fatty acid or the number of carbon atoms in the alkyl chain of the amine, it is preferable from the viewpoint of suppressing crystallization that the difference between (number of carbon atoms in R + 1) and the number of carbon atoms in R1 is between 1 and 12. It is more preferable that the number of carbon atoms in the fatty acid is greater than the number of carbon atoms in the longest alkyl chain of the amine. In other words, it is preferable that (number of carbon atoms in R + 1) is greater than the number of carbon atoms in R1. The tertiary ammonium fatty acid salts described herein, due to the asymmetric structure of the compound molecules, are less prone to crystallization, even though they have a large number of carbon atoms. As a result of achieving both the friction-reducing effect of the long alkyl chain and stability on the surface of magnetic recording media (resistance to crystallization), they are thought to exhibit excellent friction properties.

[0027] A particularly preferred combination, from the viewpoint of suppressing crystallization, is when (number of carbon atoms in R + 1) is between 19 and 23, the number of carbon atoms in R1 is between 10 and 18, and the difference between (number of carbon atoms in R + 1) and the number of carbon atoms in R1 is between 1 and 8.

[0028] R2 and R3 are each alkyl groups, and may be the same or different from each other. R2 and R3 are preferably alkyl groups having 12 or fewer carbon atoms, and more preferably alkyl groups having 6 or fewer carbon atoms. Examples of R2 and R3 include dodecyl, decyl, octyl, heptyl, hexyl, pentyl, butyl, propyl, ethyl, and methyl groups, among which butyl, propyl, ethyl, and methyl groups are preferred, and methyl groups are even more preferred. It is preferable that both R2 and R3 are one of butyl, propyl, ethyl, or methyl groups, and it is even more preferable that both R2 and R3 are methyl groups. Furthermore, it is preferable that R2 and R3 are less than (number of carbon atoms in R + 1), and the difference between (number of carbon atoms in R + 1) and the number of carbon atoms in R2 and / or R3 is more preferably 1 or more, 5 or more and 25 or less, and even more preferably 10 or more and 25 or less.

[0029] The compound represented by formula (1) is suitable as a lubricant for magnetic tape, reducing both the coefficient of friction during low-speed and high-speed tape operation. Furthermore, it exhibits high solubility in solvents commonly used to form the magnetic layer, such as 2-butanone, toluene, and cyclohexane, allowing magnetic tape to be manufactured without significantly altering conventional magnetic tape manufacturing methods or conditions. In addition, crystallization of the lubricant on the surface of the magnetic tape is less likely to occur, allowing the lubricant to be applied at the desired concentration.

[0030] [Method for producing tertiary ammonium salts of fatty acids] The method for producing the fatty acid tertiary ammonium salt according to this disclosure is not particularly limited. For example, it can be produced by dissolving a tertiary amine compound having the target hydrocarbon group and an equimolar amount of fatty acid in a solvent or without a solvent, heating under reflux, and then removing the solvent. The solvent is not particularly limited as long as it can dissolve the raw material amine and fatty acid, and may be, for example, ethanol, diethyl ether, 2-butanone, etc. Heating under reflux can be carried out, for example, at 35 to 80°C for 0.5 to 15 hours.

[0031] The obtained compounds can be identified, for example, by nuclear magnetic resonance spectroscopy (NMR) or Fourier transform infrared spectroscopy (FTIR) measurements. When identifying compounds by NMR measurements, the methyl group of tetramethylsilane (TMS) is used as a standard. 1 The target compound can be identified by 1H-NMR measurement.

[0032] [Composition] The compositions according to this disclosure are compositions comprising at least one of the above-mentioned tertiary ammonium fatty acid salts. The compositions according to this disclosure may further contain components other than the above-mentioned tertiary ammonium fatty acid salts. If the composition contains components other than the above-mentioned tertiary ammonium fatty acid salts, the proportion of the tertiary ammonium fatty acid salt according to this disclosure to the whole composition is not limited as long as the effects according to this disclosure are obtained, but it is preferable that the composition contains 50 wt% or more of the tertiary ammonium fatty acid salt represented by formula (1) or (2) above, more preferably 80 wt% or more, and preferably substantially consists only of the tertiary ammonium fatty acid salt represented by formula (1) or (2) above. The compositions according to this disclosure may also contain fatty acids and tertiary amines, which are raw materials for the above-mentioned tertiary ammonium fatty acid salts. The compositions according to this disclosure are solid at room temperature and may be provided as a powder or granular composition, or they may be dissolved in a solvent and provided as a solution.

[0033] [Lubricant] The tertiary ammonium fatty acid salts and compositions described above according to this disclosure can be used as lubricants. The lubricants according to this disclosure include the tertiary ammonium fatty acid salts described above, or the tertiary ammonium fatty acid salt compositions described above. The lubricants according to this disclosure can be suitably used as lubricants for magnetic recording media, particularly as lubricants for magnetic tapes. Primary and secondary amines, which are sometimes used as lubricants for magnetic tapes, have active hydrogen and react with other components (e.g., isocyanates) used in the manufacture of magnetic recording media, reducing the strength of the magnetic layer coating and causing issues such as shedding of magnetic powder. On the other hand, the tertiary ammonium salts according to this disclosure are considered to have low reactivity and can maintain lubrication performance.

[0034] The tertiary ammonium salts or compositions described above are compounds that are solid at room temperature and may be provided as powders or granules. When applied to magnetic recording media (coated or added to magnetic layers), it is preferable that the fatty acid tertiary ammonium salts or compositions described above be dissolved in a solvent as needed and used as a solution. Examples of solvents used when applied to magnetic recording media include hydrocarbon solvents such as diisopropyl ether, n-hexane, 2-butanone (methyl ethyl ketone), toluene, and cyclohexanone. When used as a solution, the content of the tertiary ammonium salt compound according to this disclosure in the lubricant containing the solvent is not particularly limited as long as it does not impair the performance of the lubricant, but is preferably 0.001 to 40.0 g / L, and more preferably 0.05 to 20.0 g / L.

[0035] By using the lubricant according to this disclosure in a magnetic recording medium, excellent lubrication is maintained both during low-speed operation (e.g., at the start of magnetic tape operation) and high-speed operation. Furthermore, since the lubricant is less likely to precipitate on the surface of the magnetic recording medium, it can be mixed into the magnetic layer in a high-concentration solution or applied to the magnetic layer, and the lubricating effect is sustained even after long-term use. This provides excellent running performance and durability. While the lubricant according to this disclosure is suitable as a lubricant for magnetic recording media, it can also be applied as a lubricant to polymer films and other materials that do not contain a magnetic layer.

[0036] [Magnetic recording medium] The magnetic recording medium according to this disclosure comprises a non-magnetic support and a magnetic layer laminated on the non-magnetic support, and contains the above-mentioned lubricant. The magnetic layer may also contain the above-mentioned lubricant. The magnetic layer containing the lubricant means that the lubricant is internally added to the magnetic layer. When the lubricant is internally added, it seeps out onto the surface of the magnetic recording medium and exhibits lubricity. Furthermore, the magnetic recording medium according to this disclosure comprises a non-magnetic support and a magnetic layer laminated on the non-magnetic support, with a lubricant layer formed on the magnetic layer, and the lubricant layer may contain the above-mentioned lubricant. The non-magnetic support may also contain the above-mentioned lubricant. The lubricant in the non-magnetic layer plays a role in supplying lubricant to the magnetic layer. The lubricant may be contained in either the non-magnetic support or the magnetic layer, or in both.

[0037] Examples of magnetic recording media include magnetic tapes and magnetic disks. From the viewpoint of reducing the coefficient of friction and improving durability, magnetic tapes or magnetic disks are preferred as magnetic recording media.

[0038] Figure 1 is a schematic cross-sectional view showing the configuration of a magnetic tape according to this disclosure. Referring to Figure 1, the magnetic tape 1 is formed by laminating and integrating a magnetic layer 11, a non-magnetic layer 21, a base film 31, and a back coat layer 41 in this order. The non-magnetic layer and the base film constitute a non-magnetic support. In the magnetic tape of Figure 1, a lubricant is added to the magnetic layer 11. The lubricant may also be added to the magnetic layer 11, the non-magnetic layer 21, and / or the back coat layer. The magnetic layer 11 may be in the form of pigment and magnetic powder dispersed in an organic layer containing a binder and lubricant. The lubricant seeps from the inside of the magnetic layer 11 to the surface, thereby continuously maintaining a low coefficient of friction of the magnetic tape. The non-magnetic layer 21 may be in the form of pigment and / or non-magnetic powder dispersed in an organic layer containing a binder and lubricant. In addition, the magnetic layer 11 and the non-magnetic layer 21 may contain other additives. Examples of additives include dispersants, dispersing aids, fungicides, antistatic agents, and antioxidants.

[0039] The pigment contained in the magnetic layer 11 is not particularly limited as long as it is a component found in known magnetic tapes, and examples include abrasives such as alumina and carbon black powder. The magnetic powder contained in the magnetic layer 11 is not particularly limited as long as it is a component found in known magnetic tapes, and examples include ferromagnetic iron oxide particles such as γ-Fe2O3 and cobalt-coated γ-Fe2O3, ferromagnetic chromium dioxide particles, ferromagnetic metal particles made of metals such as Fe, Co, and Ni, and alloys containing these, and hexagonal plate-shaped hexagonal ferrite fine particles. Examples include hexagonal ferrite, epsilon-type iron oxide (ε-iron oxide), Co-containing spinel ferrite, gamma hematite, magnetite, chromium dioxide, and cobalt-coated iron oxide. The crystal structure of hexagonal ferrite is composed of at least iron atoms, divalent metal atoms, and oxygen atoms. Divalent metal atoms are metal atoms that can become divalent cations as ions, and examples include strontium atoms, barium atoms, alkaline earth metal atoms such as calcium atoms, and lead atoms. Examples of hexagonal ferrites include hexagonal strontium ferrite and hexagonal barium ferrite.

[0040] Examples of binders included in the organic layers constituting the magnetic layer 11 and the non-magnetic layer 21 include polymers such as vinyl chloride, vinyl acetate, vinyl alcohol, vinylidene chloride, acrylic acid esters, methacrylic acid esters, styrene, butadiene, and acrylonitrile, or copolymers combining two or more of these, polyurethane resins, polyester resins, epoxy resins, etc. Hydrophilic polar groups such as sulfonic acid groups, carboxyl groups, and phosphate groups may be introduced into the binder to improve the dispersibility of the magnetic powder. The binder is not particularly limited as long as it is generally used in magnetic tapes, and examples include crosslinked polyurethane resins or vinyl chloride resins, thermosetting resins, or reactive resins.

[0041] The base film 31 is a layer that functions as a support for the magnetic tape. Examples of materials for the base film 31 include polyester, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polycyclohexylene dimethylene terephthalate (PCT), polyethylene-p-oxybenzoate (PEB), aramid (aromatic polyamide), polyethylene bisphenoxycarboxylate, etc., and one or more of these may be used in combination.

[0042] The back coat layer 41 is a layer for improving the running performance of the magnetic tape. The back coat layer 41 may contain a lubricant. Examples of materials for the back coat layer 41 include polyurethane resins containing carbon and calcium carbonate, nitrocellulose resins, polyester resins, etc.

[0043] Referring to Figure 2, in another embodiment of the present disclosure, the magnetic tape 2 has a lubricant layer 52, a magnetic layer 12, a non-magnetic layer 21, a base film 31, and a back coat layer 41 laminated in this order and integrated. In the magnetic tape 2 of Figure 2, the lubricant layer 52 is held on the surface of the magnetic layer 12, thereby reducing the coefficient of friction and maintaining the durability of the magnetic tape 2. The magnetic layer 12 may or may not contain a lubricant.

[0044] The specific dimensions of the magnetic tape are not particularly limited, but the thickness of the magnetic tape may be, for example, about 3 to 80 μm, and more specifically, about 3 to 10 μm. Generally, among the layers constituting the magnetic tape, the base film 31 has the greatest thickness. The thickness of the base film may be, for example, 3 to 80 μm, preferably 3 to 20 μm, and more preferably 3 to 10 μm.

[0045] The thickness of the magnetic layer 11 can be optimized according to the corresponding recording device and the bandwidth of the recording signal, and is not particularly limited, but from the viewpoint of high-density recording, it may be 10 nm to 150 nm, preferably 20 nm to 120 nm, and more preferably 30 nm to 100 nm. In a magnetic tape, at least one magnetic layer is sufficient, but two or more magnetic layers with different magnetic properties may be provided. If the magnetic layer includes multiple layers, the sum of the thicknesses of the multiple magnetic layers may be within the aforementioned range.

[0046] The thickness of the non-magnetic layer 21 is not particularly limited, but may be, for example, 10 nm to 500 nm, and preferably 50 nm to 300 nm. The thickness of the back coat layer 41 is not particularly limited, but may be, for example, 0.9 μm or less, and preferably 0.1 to 0.7 μm.

[0047] When a lubricant layer 52 is provided on the outermost surface of a magnetic tape, as shown in Figure 2 (magnetic tape 2), the thickness of the lubricant layer 52 may be, for example, about 0.1 to 10 nm, and preferably about 0.5 to 5 nm. Within this range, lubrication performance can be obtained while maintaining surface uniformity.

[0048] The thickness of each layer constituting a magnetic tape can be measured by known film thickness measurement methods. For example, a cross-section of the magnetic tape in the thickness direction can be exposed using known methods such as an ion beam or microtome, and then the exposed cross-section can be observed with a scanning electron microscope. The thickness of each layer can then be determined from the resulting microscope image. Alternatively, the thickness of each layer can be determined as a design thickness calculated from the manufacturing conditions.

[0049] When the lubricant according to this disclosure is added to a magnetic layer, the content ratio of the lubricant in the magnetic layer is not limited as long as the effects according to this disclosure are obtained, but may be, for example, about 0.1 to 5.0 wt%, and preferably about 0.3 to 3.0 wt%. Within this range, lubrication performance can be obtained while maintaining surface uniformity.

[0050] When the lubricant according to this disclosure is applied to the surface of a magnetic tape as a lubricant layer, the amount of lubricant applied to the magnetic tape is not limited as long as the effects according to this disclosure are obtained, but for example, 0.1 to 5.0 mg / m² 2 It can be around 0.5-3 mg / m². 2 It is preferable that the range be within this range. Within this range, lubrication performance can be obtained while maintaining surface uniformity.

[0051] [Examples] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples.

[0052] [Synthesis of Compounds] The compounds of Examples 1-6 and Comparative Examples 1-3 were obtained by following the procedure below. Each compound was analyzed using the JEOL JNM-ECX400. 1 The structure was identified by 1H-NMR measurement. Chloroform-d was used as the solvent and TMS as the reference material.

[0053] <Example 1> Dimethyloctadecylamine and an equivalent amount of arachidic acid were dissolved in ethanol and heated under reflux for 1 hour. The solvent was then removed to obtain the target compound, dimethyloctadecylammonium arachidate (compound 1). 1 H-NMR(400MHz,CDCl3) δ(ppm):2.532(2H t / J=8.0Hz), 2.412(6H s), 2.244(2H t / J=7.9Hz), 1.954-1.557(4H m), 1.271-1.238(62H m), 0.864(6Ht / J=7.0Hz)

[0054] <Example 2> Dimethylhexadecylamine and an equivalent amount of arachidic acid were dissolved in ethanol and heated under reflux for 1 hour. The solvent was then removed to obtain the target compound, dimethylhexadecylammonium arachidate (compound 2). 1H-NMR (400 MHz, CDCl₃) δ (ppm): 2.554 (2H t, J=8.2 Hz), 2.427 (6H s), 2.242 (2H t, J=7.6 Hz), 1.614-1.536 (4H m), 1.273-1.238 (58H m), 0.865 (6H t, J=6.8 Hz)

[0055] <Example 3> Dimethyldodecylamine and an equimolar amount of arachidic acid were dissolved in ethanol and heated under reflux for 1 hour. Thereafter, the solvent was removed to obtain the target dimethyldodecylammonium arachidate (compound 3). 1 H-NMR (400 MHz, CDCl₃) δ (ppm): 2.591 (2H t, J=8.2 Hz), 2.422 (6H s), 2.227 (2H t, J=7.6 Hz), 1.625-1.502 (4H m), 1.269-1.235 (50H m), 0.861 (6H t, J=6.6 Hz)

[0056] <Example 4> Dimethyloctadecylamine and an equimolar amount of behenic acid were dissolved in ethanol and heated under reflux for 1 hour. Thereafter, the solvent was removed to obtain the target dimethyloctadecylammonium behenate (compound 4). 1 H-NMR (400 MHz, CDCl₃) δ (ppm): 2.533 (2H t, J=8.2 Hz), 2.418 (6H s), 2.258 (2H t, J=7.6 Hz), 1.582 (4H quintet, J=7.9 Hz), 1.276-1.196 (66H m), 0.865 (6H t, J=6.8 Hz)

[0057] <Example 5> Dimethylhexadecylamine and an equimolar amount of behenic acid were dissolved in ethanol and heated under reflux for 1 hour. Thereafter, the solvent was removed to obtain the target dimethylhexadecylammonium behenate (compound 5). 1H-NMR(400MHz,CDCl3) δ(ppm):2.558(2H t / J=7.8Hz), 2.431(6H s), 2.238(2H t / J=7.6Hz), 1.614-1.537(4H m), 1.273-1.238(62H m), 0.865(6Ht / J=6.8Hz)

[0058] <Example 6> Dimethyldodecylamine and an equivalent amount of behenic acid were dissolved in ethanol and heated under reflux for 1 hour. The solvent was then removed to obtain the target dimethyldodecylammonium behenate (compound 6). 1 H-NMR(400MHz,CDCl3) δ(ppm):2.537(2H t / J=8.0Hz), 2.413(6H s), 2.230(2H t / J=7.6Hz), 1.609-1.554(4H m), 1.282-1.237(54Hm), 0.862(6Ht / J=6.8Hz)

[0059] <Comparative Example 1> The desired dimethyloctadecylammonium stearate (compound 7) was obtained in the same manner as in Example 1, except that arachidic acid was replaced with stearic acid.

[0060] <Comparative Example 2> The desired dimethylicosanylammonium arachidate (compound 8) was obtained in the same manner as in Example 1, except that dimethyloctadecylamine was replaced with dimethylicosanyl(C20)amine.

[0061] <Comparative Example 3> The target dimethyldocosylammonium arachidate (compound 9) was obtained in the same manner as in Example 4, except that dimethyloctadecylamine was replaced with dimethyldocosyl(C22)amine.

[0062] [Preparation of evaluation samples (magnetic recording media)] The compounds obtained in Examples 1-6 and Comparative Examples 1-3 were dissolved in a solvent (isopropyl alcohol (IPA) or diisopropyl ether (DIPE)) to concentrations of 0.1 wt%, 0.5 wt%, and 1.0 wt%, respectively. The resulting solutions were coated onto the surface of a magnetic tape (Fujifilm Corporation, LTO Ultrium9) with a wet thickness of 4 μm, and the solvent was evaporated by natural drying for 2 hours to prepare magnetic recording media for evaluation. As a blank, a sample was prepared by coating the surface of a magnetic tape with only a solvent, allowing it to air dry for 2 hours to evaporate the solvent.

[0063] [Evaluation of magnetic recording media] (1) Surface precipitation The surface of each evaluation sample was observed under a microscope to check for the presence or absence of lubricant deposition on the tape surface. Lubricant deposition on the sample surface impairs the smoothness and uniformity of the magnetic tape surface. (2)Low speed friction characteristics Friction was measured using a friction and wear testing machine (Tribogear) TYPE 40 manufactured by Shinto Kagaku Co., Ltd. under the following test conditions. Test ball: SUJ2 (10mm diameter) Load capacity: 50gf Sliding speed: 1.0 mm / sec. Sliding distance: 5 mm, 5 reciprocating motions Tests were conducted at three different locations on the evaluation sample, and the arithmetic mean of the obtained friction coefficients was defined as the friction coefficient (u). The low-speed friction coefficient was defined as the value obtained by normalizing the friction coefficient (u) with respect to the blank friction coefficient (u0) (u std = u / u0). (3) High-speed friction characteristics Friction was measured using a friction measuring device equipped with a magnetic tape fixing part having a load sensor and a rotatable AlTiC cylinder (radius 3.0 cm) arranged in the following procedure. A schematic diagram of the friction measuring device is shown in Figure 3. In Figure 3, the friction measuring device 3 comprises a fixing part 31, a weight 32, and a rotating body 33, and the evaluation sample S is fixed at one end to the fixing part 31 and at the other end to the weight 32. 1. One end of the sample for evaluation was secured with the tape fixing part, the magnetic tape was hung over the outer circumference of the cylinder, and a weight (100g) was attached to the other end before it was placed on the measuring machine. 2. The test was started by rotating the cylinder at a sliding speed of 0.1 m / s under stable conditions of temperature: 21-25°C and relative humidity: 40-60%. 3. The average value of the coefficient of kinetic friction was measured between 90 and 100 seconds after the start of the test. 4. The average value of the kinetic friction coefficient of the blank was set to 1.0, and the relative value of the average kinetic friction coefficient of each evaluation sample was calculated. This value was defined as the high-speed friction coefficient.

[0064] Table 1 shows the structural formulas and evaluation results of the compounds in Examples 1-6 and Comparative Examples 1-3. In Table 1, "-" indicates that crystal precipitation occurred on the surface of the evaluation sample. For samples where crystal precipitation occurred, the coefficient of friction was not measured because the surface was not uniform. [Table 1]

[0065] As shown in Table 1, no surface precipitation occurred on the magnetic recording media coated with the compounds of Examples 1 to 6, regardless of the solution concentration (0.1 wt%, 0.5 wt%, and 1.0 wt%). In particular, Example 4, despite being expected to be the most likely to crystallize due to its fatty acid having 22 carbon atoms (the highest number among compounds 1 to 9), did not exhibit surface precipitation.

[0066] In contrast, the fatty acid octadecylammonium salt using an amine with 18 carbon atoms in Comparative Example 1 showed surface precipitation when applied to magnetic recording media at solution concentrations of 0.5 wt% and 1.0 wt%. Magnetic recording media coated with the compounds of Comparative Examples 2 and 3 showed surface precipitation at solution concentrations of 0.1 wt%, 0.5 wt%, and 1.0 wt%. Figure 4 shows surface photographs of magnetic recording media in Example 4 (1.0 wt%) and Comparative Example 1 (1.0 wt%). The scale bar in the photograph is 20 μm. As shown in Figure 4, no precipitation was observed on the surface of the magnetic recording media in Example 4, whereas crystallized lubricant was observed in Comparative Example 1.

[0067] Regarding the low-speed friction coefficient, at 0.1 wt%, the magnetic recording media of Examples 1 to 6 exhibited reduced friction relative to the blank. Comparative Example 1 also showed an effect equivalent to that of Examples 1 to 6. However, at 0.5 wt% and 1.0 wt%, precipitation occurred in all Comparative Examples 1 to 3, and thus the friction coefficient could not be reduced by increasing the concentration, whereas Examples 1 to 6 all showed a significant friction reduction effect. Regarding the high-speed friction coefficient, at 0.1 wt%, the magnetic recording media of Examples 1 to 6 showed reduced friction relative to the blank, and the friction reduction effect was greater than that of Comparative Example 1. At 0.5 wt% and 1.0 wt%, precipitation occurred in Comparative Examples 1 to 3, whereas no precipitation occurred in Examples 1 to 6, and the friction reduction effect was almost the same as that of 0.1 wt%. In other words, the high-speed friction reduction effect of Examples 1 to 6 did not decrease even with increased concentration.

[0068] In the above test, the evaluation was performed on a sample in which a lubricating layer was created on top of a magnetic layer. However, since the same solvent is used when the lubricant is added to the magnetic layer, it is expected that a similar trend will be observed.

[0069] The embodiments disclosed herein should be understood to be illustrative in all respects and not restrictive in any way. The scope of the present invention is defined by the claims and is intended to include all modifications in the sense and scope equivalent to the claims. [Explanation of Symbols]

[0070] 1,2 Magnetic tape, 11,12 Magnetic layer, 21 Non-magnetic layer, 31 Base film, 41 Back coat layer, 51 Lubricant layer, 3 friction measuring instrument, 31 fixed part, 32 weight, 33 rotating body.

Claims

1. A tertiary ammonium salt of a fatty acid, represented by the following formula (1). 【Chemistry 1】 (In formula (1), R is an alkyl group having 18 or more carbon atoms, R １ R is an alkyl group having 10 or more carbon atoms. ２ and R ３ Each of these represents an alkyl group. However, R ２ and R ３ The number of carbon atoms in each of them is R １ The number of carbon atoms is less than or equal to (the number of carbon atoms in R + 1) and R １ ~R ３ (The number of carbon atoms in each of these atoms is different from that of the others.)

2. In the above formula (1), R is an alkyl group having 18 to 23 carbon atoms, and R １ is an alkyl group having 10 to 24 carbon atoms, the tertiary ammonium fatty acid salt according to claim 1.

3. In the above formula (1), R ２ and R ３ The fatty acid tertiary ammonium salt according to claim 1, wherein each of them is an alkyl group having 12 or fewer carbon atoms.

4. In (1) above, R, R １ , R ２ and R ３ The fatty acid tertiary ammonium salt according to claim 1, wherein each of the elements is a linear alkyl group.

5. In formula (1) above, (number of carbon atoms in R + 1) and R １ The fatty acid tertiary ammonium salt according to claim 1, wherein the difference in the number of carbon atoms is 1 or more and 12 or less.

6. A tertiary ammonium fatty acid salt composition comprising at least one of the tertiary ammonium fatty acid salts described in any one of claims 1 to 5.

7. A lubricant for magnetic recording media comprising at least one of the tertiary ammonium salts of fatty acids described in any one of claims 1 to 5.

8. A magnetic recording medium comprising a non-magnetic support and a magnetic layer laminated on the non-magnetic support, and containing the lubricant for magnetic recording media described in claim 7.

9. The magnetic recording medium according to claim 8, wherein the magnetic layer includes the lubricant for the magnetic recording medium.

10. The magnetic recording medium according to claim 8, further comprising a lubricant layer laminated on the magnetic layer, wherein the lubricant layer contains the lubricant for the magnetic recording medium.

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