JP2660287B2 - Magnetic recording media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium, and more particularly, to a magnetic recording medium having excellent running properties and durability.

[Conventional technology]

In general, a magnetic recording medium made by binding a magnetic powder together with a binder component onto a base film, for example, comes into intense sliding contact with a magnetic head or the like during recording and reproduction, so that the magnetic layer is easily worn.

Therefore, an ester lubricant containing one ester group in the molecule, such as n-butyl stearate in the magnetic layer, an ester lubricant containing two ester groups, such as maleate, and the like, An ester-based lubricant containing three ester groups such as glycerin tristearate may be contained (JP-A-54-124706, JP-A-56-80).
No. 829, JP-A-56-119933), or a protective layer and a backcoat layer containing these ester-based lubricants and an undercoat layer are further provided (JP-A-59-120838, JP-A-59-19).
No. 5,131, JP-A-59-197685, JP-A-59-229418, and JP-A-59-261763) to improve running performance and durability.

[Problems to be solved by the invention]

However, these conventionally used ester lubricants have not yet been able to sufficiently improve the running property and durability. For example, an ester lubricant containing three ester groups is incompatible with the binder resin. Is too good in compatibility and does not bleed out sufficiently, resulting in low lubricating effect.Those with a molecular weight of 320 or less have too low a molecular weight and are dissipated during storage and use. When an ester lubricant having a linear hydrocarbon group is used for a magnetic disk or the like, there is a problem that the magnetic head is attracted to the magnetic disk and the motor torque at the time of starting the magnetic disk becomes too high.

[Means for solving the problem]

The present invention has been made in light of such circumstances, and has been made as a result of various studies. Or (However, R ₁ and R ₃ are a linear or branched hydrocarbon group having 8 to 20 carbon atoms, and R ₂ and R ₄ are 0 to 0 carbon base paper.
4 linear or branched hydrocarbon groups, M is (CH ₂ )
n represented by n is a residue of an alicyclic compound having 3 to 7; The runnability and durability were sufficiently improved by including the aliphatic ester lubricant represented by the formula (1) on the front or back surface of the magnetic recording medium having the magnetic layer, or on the interface between the magnetic layer and the substrate. Things.

In the aliphatic ester lubricant used in the present invention, since a bulky cyclic portion is introduced into the molecular skeleton of the ester lubricant, the interaction between the lubricant molecules is appropriately weakened, and the lubricant is used. Without being dissipated, the adsorption phenomenon in which the magnetic head is attracted to the magnetic disk is suppressed, and the lubrication performance is improved. Thus, when this is contained in the magnetic layer, or in the protective layer on the magnetic layer, the back coat layer on the back of the substrate, and further contained in the undercoat layer under the magnetic layer,
The excellent lubricating performance of this kind of fatty-side ester-based lubricant is continuously exhibited for a long time, and there is no adsorption phenomenon in which the magnetic head is adsorbed to the magnetic disk, so that the running property and the durability are sufficiently improved.

The aliphatic ester lubricant having such a cyclic structure preferably has a molecular weight in the range of 320 to 850.If the molecular weight is smaller than 320, this kind of lubricant is dissipated during storage and use. If the diameter is larger than 850, the magnetic head and the magnetic recording medium are attracted to each other, resulting in running failure.

The content of the aliphatic ester-based lubricant having a cyclic structure of this kind is 0.5 to 2 with respect to all of these constituents in the magnetic layer, the protective layer, the backcoat layer and the undercoat layer.
The content is preferably in the range of 5% by weight. If the amount is too small, the desired effect cannot be obtained. If the amount is too large, the bleed-out is too large and the magnetic recording media adhere to each other.

Specific examples of the aliphatic ester-based lubricant having such a cyclic structure include, for example, chemical formula And the like.

The magnetic layer containing such an aliphatic ester lubricant having a cyclic structure is prepared by mixing and dispersing an aliphatic ester lubricant having a cyclic structure together with a magnetic powder, a binder resin, an organic solvent, and the like to prepare a magnetic paint. Then, the magnetic paint is applied to a substrate and dried.

As the magnetic powder used here, for example, γ-
Fe ₂ O ₃ powder, Fe ₃ O ₄ powder, Co-containing γ-Fe ₂ O ₃ powder, Co-containing F
Conventionally widely used magnetic powders such as e ₃ O ₄ powder, Fe powder, Co powder, and Fe—Ni powder are widely included.

As the binder resin, for example, vinyl chloride-
Binder resins generally used in magnetic recording media such as vinyl acetate copolymers, cellulose resins, polyvinyl butyral resins, polyester resins, polyurethane resins, and isocyanate compounds are all used.

As the organic solvent, any of the conventionally used organic solvents such as methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, ethyl acetate, and toluene can be used alone or in combination.

In addition, a protective layer containing an aliphatic ester lubricant having a cyclic structure is prepared by mixing and dispersing an aliphatic ester lubricant having a cyclic structure together with a filler, a binder resin, an organic solvent, and the like to prepare a coating for the protective layer. The protective layer paint is applied on the magnetic layer and dried to form a back coat layer containing an aliphatic ester-based lubricant having a cyclic structure. The back coat layer is filled with redwood, barium sulfate, calcium carbonate, carbon black, and the like. A backcoat layer paint is prepared by mixing and dispersing an aliphatic ester lubricant having a cyclic structure together with an agent, a binder resin and an organic solvent, etc. It is formed by applying and drying on the back surface.

Furthermore, the undercoat layer containing the aliphatic ester lubricant having a cyclic structure is prepared by mixing and dispersing the aliphatic ester lubricant having a cyclic structure together with a filler, a binder resin, an organic solvent, and the like to prepare a paint for the undercoat layer. The undercoat layer paint is applied on a substrate and dried.

Examples of the magnetic recording medium include various forms of a structure that is in sliding contact with a magnetic head, such as a magnetic tape having a synthetic resin film such as a polyester film as a base, a magnetic disk or a magnetic drum having a disk or a drum as a base.

〔Example〕

 Next, an embodiment of the present invention will be described.

Examples 1 to 17 Co-containing γ-Fe ₂ O ₃ powder 300 parts by weight (6500 Oersted) was used by using an aliphatic ester lubricant having a cyclic structure composed of an alcohol component and an acid component shown in Table 1 below. Nitrocellulose H1 (Nitrocellulose, manufactured by Asahi Kasei 28K), N-2301 (Polyurethane resin manufactured by Nippon Polyurethane Industry Co., Ltd.) Coronate L (manufactured by Nippon Polyurethane Co., Ltd., trifunctional) Low-molecular-weight isocyanate compound) Carbon black 60 〃α-alumina 10 潤滑 Lubricant shown in Table 1 12 メ チ ル Methyl isobutyl ketone 280 ト ル エ ン Toluene 280 〃 The composition is mixed and dispersed in a ball mill for 96 hours to prepare a magnetic paint. Then, this magnetic paint was applied on both surfaces of a polyester film having a thickness of 70 μm to a dry thickness of 1.2 μm and dried to form a magnetic layer. After that, the disk was punched out to make a magnetic disk.

Comparative Examples 1 to 7 In the composition of the magnetic paint in Example 1, the same amount of the aliphatic ester lubricant shown in Table 2 was used instead of the aliphatic ester lubricant having a cyclic structure shown in Table 1. A magnetic disk was prepared in the same manner as in Example 1 except that the above procedure was performed.

The durability of each of the magnetic disks obtained in each of the examples and comparative examples was tested, and the starting torque was measured. In the durability test, the obtained magnetic disk was repeatedly written and read on the same track under the conditions of 45 ° C. and 30% RH, and the time until a crash occurred was measured. The starting torque was determined by running the same track for 10 hours, placing the magnetic head on the magnetic disk, stopping the running, and measuring the starting torque of the magnetic disk one hour later.

 Table 3 below shows the results.

[Effects of the Invention] As is clear from the above Table 3, the magnetic tapes obtained in the present invention (Examples 1 to 17) are more durable than the conventional magnetic tapes (Comparative Examples 1 to 7). The magnetic recording medium obtained according to the present invention has improved runnability and durability even further because of its good performance and small starting torque.

Claims (3)

(57) [Claims] A magnetic recording medium having a magnetic layer on the surface of a substrate, a front surface or a back surface, or an interface between the magnetic layer and the substrate, Or (However, R ₁ and R ₃ are a straight-chain or branched hydrocarbon group having 8 to 20 carbon atoms, and R ₂ and R ₄ are 0-carbon atoms.
To 4 linear or branched hydrocarbon groups, M is (C
N represented by H ₂₎ n is a residue of an alicyclic compound 3-7. A magnetic recording medium characterized by containing an aliphatic ester-based lubricant having a cyclic structure represented by the formula (1). 2. The magnetic recording medium according to claim 1, wherein the aliphatic ester lubricant having a cyclic structure is an aliphatic ester lubricant having a molecular weight of 320 to 850. 3. The composition according to claim 1, wherein the aliphatic ester lubricant having a cyclic structure is contained in an amount of 0.5 to 25% by weight based on all components of the layer containing the aliphatic ester lubricant having a cyclic structure. The magnetic recording medium according to claim 2.