JPS5864630A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:The enhance the lubricity and wear resistance by incorporating a specified carboxyl modified org. silicone compound to a magnetic layer. CONSTITUTION:A carboxyl modified org. silicone compound represented by the general formula (where each of R1 and R2 is -CH3 or R3COOH, R3 is 1-26C hydrocarbon group, n1 is an integer of 0-<1,000, n2 is an integer of 1-500 and n1+n2<=1,000) is incorporated to a magnetic layer using a binder contg. polyurethane resin with <=10,000mol.wt. Said silicone compound has a hydrocarbon group having a carboxyl group with a great affinity for the binder in the principal chain, or it has such hydrocarbon groups in the principal chain and at both terminals of the principal chain.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and an object thereof is to improve the lubricity and wear resistance of a magnetic layer, and to provide a magnetic recording medium that has excellent running stability and durability. be.

In general, magnetic recording media such as magnetic tapes, which are made by coating a magnetic paint consisting of magnetic powder, binder, organic solvent, and other necessary components on a substrate such as a polyester film, do not come into contact with magnetic heads, guide members, etc. The magnetic layer must have a low coefficient of friction and excellent running stability, and since it comes into intense sliding contact with the magnetic head during playback, the magnetic layer has little wear and tear and is highly durable. It is required that the

Therefore, as a measure to improve the lubricity and wear resistance of the magnetic layer, lubricants such as silicone oil have been incorporated into the magnetic layer. A proposal is made in which an organosilicone compound modified with fatty acids shown by #1 (II) is contained in a magnetic sleeve containing a binder that has good compatibility with this type of silicone compound such as a polyurethane resin. has been done.

(However, in the formula, R1 and R2 are nonazated or unsaturated hydrocarbon groups having 7 to 21 carbon atoms, and n is an integer of θ to 50.

) OCH.

(However, in the formula, R1, R1 and R, tj have 7 to 2 carbon atoms.
1 saturated or unsaturated hydrocarbon group, m an integer of 1 to 100, n an integer of 0 to 250, m+n≦300,
However, although silicone oil has excellent lubricity, it has poor compatibility with the binder, making the magnetic layer inhomogeneous and causing pinholes to form on the surface of the magnetic layer. In addition, the fatty acid-modified organosilicone compounds represented by the general formulas (1) and (1) have fatty acid residues at both ends or in the main chain that have excellent affinity with the binder. Compatibility with the binder is improved, especially when used in combination with a binder with good compatibility such as polyurethane resin, the compatibility becomes moderately good and the lubrication effect is fully demonstrated, improving the lubricity and wear resistance of the magnetic layer. However, when used in combination with a polyurethane resin with a molecular weight of 10,000 or less, the compatibility is poor and the resin is too thin, and the fatty acid-modified organosilicone compound is too compatible with the binder due to its terminal alkyl group, resulting in good leaching onto the surface of the magnetic layer. Otherwise, the inherent lubricating effect of the silicone compound is no longer fully exhibited, and the lubricity and wear resistance of the magnetic layer cannot be sufficiently improved.

The inventors conducted various studies in view of the above circumstances and found that the general formula (in the formula, R1 and R2 #1-C) i5 t or -
RC0OHSR5 represents a hydrocarbon group having 1 to 26 carbon atoms, and n and R2 are 0≦n, <'1000.1≦n2
It is an integer of ≦500 and fl I +n 2≦1000. ) When the carboxyl-modified organosilicone compound represented by ) is contained in a magnetic layer containing a polyurethane resin with a molecular weight of 1oooo or less as a binder, the compatibility with the binder becomes moderately good because the terminal is a carboxyl group, and the magnetic layer becomes It has been discovered that the lubricity and wear resistance of the magnetic layer can be sufficiently improved by oozing out to the surface in an appropriate amount, and this invention has been completed.

The carboxyl-modified organosilicone compound used in this invention is a hydrocarbon group having carboxyl groups that have excellent affinity with a binder in the main chain, in the main chain, and at both ends of the main chain, as shown in the general formula above. It is moderately compatible with the binder and has a molecular weight of 10,000.
Even when used in combination with a binder containing the following polyurethane resin, it does not become too compatible with conventional fat-loaded organosilicone compounds and reliably exudes onto the surface of the magnetic layer.

In addition, these hydrocarbon groups having carboxyl groups have lubricity, and together with the main chain consisting of an organic silicone compound with excellent lubricity, these hydrocarbon groups having carboxyl groups also exert a lubricating effect, so that the magnetic layer lubricity and wear resistance are further improved. In particular, these effects are remarkable when the main chain has hydrocarbon groups having carboxyl groups not only in the main chain but also at both ends of the main chain. A magnetic recording medium with adequate exudation, sufficiently improved lubricity and wear resistance of the magnetic layer, and excellent running stability and durability can be obtained.

In the carboxyl-modified organosilicone compound of the present invention represented by the above general formula, R3 of the hydrocarbon group having a carboxyl group represented by -R3COOII is -(]←
,-(CH,)m→! ←It is any aromatic compound or a saturated or unsaturated hydrocarbon group represented by the general formula Cn1 (2n or CnH2n-2), and the number of carbon atoms is preferably within the range of 1 to 26, and if the number of carbon atoms is less than 1, it is difficult to tolerate. If the traction property is not sufficiently improved, and the number exceeds 26, the lubricity may deteriorate on the contrary.Specific examples of such hydrocarbon groups having a carboxyl group include -C,
l(,C(X)H.

-(?, H6C00H1-C5H,.C00HN -C
,. I(28COOH%-C,,H28COOH,C2
oH4(, C00Hs C26H52COOH5-C
2) I2COOH, -C,)I4C001% -C5m
(8COOH.

C2oH56COOHq C14H26COOHs
C2oH56COOHq-C26H5oCOOH,-
C2H4-C6H, Cα)H, -C6H, COOHs, etc. are exposed.

R1 and R2Fi are hydrocarbon groups having a methyl group or the same carboxyl group as above, and when R1 and R2 are hydrocarbon groups having a carboxyl group, the compatibility with the binder is even better and moderate. , the lubricity and wear resistance of the magnetic layer are further improved. Note that R4 and R2 may be the same or may be members.

Further, the degree of polymerization, that is, n and I2 in the above general formula are 0≦
n, < 1000.1≦n2≦5004, n1+n2
Preferably, they are integers of ≦1000, and nl and n
If , is too large, it will be difficult to dissolve in organic solvents, making it difficult to form into a paint, and the lubricity and wear resistance will not be sufficiently improved.

Such carboxyl-modified organic silicone compounds of the present invention may be used alone or in combination of two or more, and at least 0.1% by weight based on the magnetic powder may be used in the magnetic layer. The effect is exhibited when it is included, and the effect becomes more pronounced as the content increases. However, if the content exceeds 10% by weight relative to the magnetic powder, it may leak excessively onto the surface of the magnetic layer, contaminating the magnetic head, and reducing output. j
It is preferable to contain the polyurethane resin in the magnetic layer within the range of 1%. Also, the polyurethane resin used as the binder in this invention with a molecular weight of 10,000 or less has a low molecular weight and is therefore not compatible with the carboxyl-modified organic silicone compound. The polyurethane resin of Carboxyl-Modified Organic Silicone Compounds is well compatible with the H-containing binder and oozes out to the surface of the magnetic layer. Such polyurethane resins have a molecular weight of 10,000 or less and have isocyanate groups or water C11 groups at both ends or some or all positions other than both ends, or have incyanate groups and hydroxyl groups at the same time. φ deviations, regardless of whether they are polyester-based or polyether-based, are also suitably used, and specific examples include Takenate L-1006, Takenate L-L manufactured by Narita Pharmaceutical Industries, Ltd.
-1007, Takene-) L-2710, Takene) TP
-50, Takelac E-5,50, Coquanate #4048 manufactured by Nippon Polyurethane Industries Co., Ltd., Coronet) R4095,
Mitsui Toatsu Heiburen $100, Heiburen #167
, Pandex P-538 manufactured by Oguchi Honki Kagaku Kogyo Co., Ltd.
, Pandex 305E, etc.

Such polyurethane resins with a molecular weight of 10,000 or less may be used alone, but they are also effective when used in combination with vinyl-vinyl acetate copolymers, vinylidene chloride copolymers, cellulose resins, vinyl butyral resins, etc. The mixing ratio when used in combination with these binders is preferably within the range of 9/1 to 1/9 in terms of the binder/polyurethane ratio, and preferably within the range of 6/4 to 4/6. is more preferable. Furthermore, it may be used in combination with a low molecular weight isocyanate compound, and when the low molecular weight isocyanate compound is used in combination, the amount of the low molecular weight isocyanate compound added is preferably within the range of 1 to 50 weight range based on the total binder. More preferably, it is within the range of 3 to 20 pounds by weight.

Examples of magnetic powder include r-Fe20S powder, F
e, 0. Powder, Co-containing r-Fe! O, powder, Co-containing Fe! In addition to O powder, Cry powder, various conventionally known magnetic powders such as Fe powder, Co powder, and Fe-Ni powder are widely included.

The organic solvent is not particularly limited, and includes solvents suitable for dissolving the carboxyl-modified organic silicone compound and binder of the present invention, for example, acetone, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, etc., and acetic acid. Ester solvents such as ethyl and butyl acetate, aromatic hydrocarbon solvents such as benzene, toluene, and xylene, alcohol solvents such as isopropyl alcohol, acid amide solvents such as dimethylformamide, tetrahydrol, dioxane, etc. Ether solvents and the like may be used alone or in combination of two or more.

In addition, various additives commonly used in magnetic paints include
For example, a dispersant, an abrasive, an antistatic agent, etc. may be optionally added.

In the present invention, a carxyl-modified organosilicone compound is contained in a magnetic layer using a polyurethane resin having a molecular weight of 10,000 or less as a binder, a carxyl-modified organosilicone compound is used as a magnetic powder, and a binder containing the polyurethane resin is used. This can be done by mixing and dispersing with an organic solvent, etc. to prepare a magnetic paint, applying this magnetic paint onto a substrate such as a polyester film, and drying it, or by dissolving the carboxyl-modified organosilicone compound in a suitable solvent. This can be carried out by spraying the solution obtained by dissolving onto a pre-sculpted magnetic layer containing the polyurethane resin as a binder, or by immersing the magnetic layer in the solution.

Next, embodiments of the invention will be described.

Example! Using a carbyl-modified organic silicone compound represented by the structural formula, γ-Fe, 05 magnetic powder 80 parts by weight VA
GH (manufactured by U, C, C, USA, chloride 12 JF
Vinyl-vinyl acetate-vinyl alcohol copolymer) Takene) L-1007 (manufactured by Takeda Pharmaceutical 71 Products Co., Ltd., urethane prepolymer) Coronae) L (manufactured by Nippon Polyurethane 11 Gyosha,
Trifunctional low molecular weight isocyanate compound) Lauric acid 11 Liquid paraffin 0.3# Carbon black
ll valve handle (α-Fe, 0.)
1 t toluene
50 I methyl isobutyl ketone 50
A magnetic coating material was prepared by mixing and dispersing a mixture consisting of 0.3# carmexyl-modified organic silicone compound using a ball ζ wheel for 70 hours. This magnetic paint was applied onto a polyester film with a thickness of 11 μm to a dry thickness of 5#, dried, and subjected to surface treatment, and then cut to a width of 3.8 mm to form a magnetic tape.

Example 2 Same as Example 1 except that in the composition of the magnetic paint in Example 1, the same amount of carboxyl-modified organic silicone compound represented by the following structural formula was used in place of the carboxyl-modified organic silicone compound having the structural formula shown in Example 1. A magnetic tape was made in the same manner as in 1.

H5 Comparative Example In the composition of the magnetic paint in Example IK, the same amount of myristic acid-modified organic silicone compound represented by the following structural formula was used in place of the carboxyl-modified organic silicone compound having the structural formula shown in Example 1. A magnetic tape was made in the same manner as in Example 1.

The magnetic tapes obtained in each example and comparative example were tested for durability, and the friction coefficient and output fluctuation were measured. Durability test Under the conditions of ti35°0,80SRH, each magnetic tape was subjected to a head load of 109 and a running speed of 4-8"/se.
The friction coefficient was determined by running the tape under the same conditions as the durability test described above and measuring the number of runs until the output decreased by 3 dB from the initial output.
The coefficient of friction with the magnetic head after running 0 times was measured. Further, the output fluctuation was measured by running the magnetic tape under the same conditions as in the durability test described above and measuring the output fluctuation after running the tape 600 times.

Geto is the result.

As is clear from the table above, 1. The magnetic tape obtained by this invention (Example 1 button and 2) is different from the conventional magnetic tape (Comparative example).
Compared to the above, the coefficient of friction and output fluctuation are small, and the durability is good. Therefore, the magnetic recording medium Fi magnetic layer obtained by the present invention has good lubricity and wear resistance, and has good running stability and durability. It can be seen that it is excellent in

Claims (1)

[Scope of Claims] 1. In a magnetic layer containing a polyurethane resin having a molecular weight of 10,000 or less as a binder, a general formula (wherein R1
and R2Fi-CI, or -RCool, R,
and a hydrocarbon group having 1 to 26 carbon atoms, n, and n
2 digits 0≦n, <too□, 1≦n≦500, n, ten n2
It is an integer of ≦1000. ) A magnetic recording medium containing an organic silicone compound represented by