JPS6292229A - Magnetic recording body and its production - Google Patents

Abstract

PURPOSE:To enable high-density recording by continuously increasing the coercive force of a magnetic film formed on a substrate from the bottom surface of the magnetic film to its surface. CONSTITUTION:The coercive force of the magnetic film is continuously increased from the bottom surface of the magnetic film to the surface of the magnetic film. The magnetic film is incorporated with at least Co or Co and Ni and further, preferably, with at least one kind between P and B. In addition to the incorporation, at least one kind selected from Re, Mn and W is preferably incorporated into the magnetic thin film. Consequently,the reversal of recording magnetization can be generated at the lower part of the magnetic film even with a feeble magnetic field, and the magnetic recording body having an excellent overwriting characteristic and appropriate for high-density recording can be obtained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a magnetic disk device, a floppy disk device,
Related to magnetic recording bodies used in magnetic recording devices such as magnetic tape devices, magnetic card loading devices, magnetic drum devices, etc., and methods for manufacturing the same (prior art) In magnetic recording devices such as magnetic disk devices, magnetic tape devices, etc. , magnetic recording medium (magnetic film) formed on a substrate
Recording is performed by magnetizing in the longitudinal or perpendicular direction using a K magnetic head. In recent years, efforts have been made to reduce the gap length of magnetic heads and increase the coercive force (He) in longitudinal recording of magnetic recording media in order to meet the requirements for high-density G groups in magnetic recording devices. In perpendicular recording, it is necessary to increase the perpendicular anisotropy of the medium, but increasing perpendicular anisotropy is often accompanied by an increase in coercive force. However, the value of coercive force depends on the recording magnetic field of the magnetic head. Limited by strength. That is, since the recording magnetic field in the vicinity of the gap of the magnetic head decreases as it moves away from the head surface in the perpendicular direction, recording magnetization reversal will not occur in the lower part of the magnetic film depending on the value of the coercive force of the magnetic film. In particular, when a magnetic head with a narrow gap length is used, the reachable range of the recording magnetic field becomes narrow, resulting in significant deterioration of override (overwriting) characteristics. For this reason, a magnetic film with a high coercive force is provided in the part close to the head, that is, in the upper layer of the magnetic film, and a magnetic film with a relatively low coercive force is provided in the lower layer of the magnetic film so that recording magnetization reversal occurs even in a weak head magnetic field. Therefore, the magnetic field g, which is considered to be a magnetic recording body suitable for high-density recording, is 0. In electroless plating methods, which are produced by coating methods, sputtering methods, vapor deposition methods, plating methods, etc., the magnetic film thickness is usually small. The value of coercive force decreases with the increase of
RNA of Filectrochemical
5ociety, Vol. 116, Now 2
, p188.

1969)) oNo''!!L As a precedent for obtaining a magnetic film with a laminated structure having a high coercive force magnetic plating layer in the upper layer and a low coercive force magnetic plating layer in the lower layer by the unraveling method, , Japanese Patent Publication No. 44-2888 (Laminated Plate Magnetic Data Device) is known.

(Problems to be Solved by the Invention) Magnetic films are manufactured by ζζ methods such as coating, sputtering, vapor deposition, and plating, but the coercive force is continuous from the bottom of the magnetic film to the surface of the magnetic film. It is not easy to obtain magnetic films that are increasing in size. The coating method results in a magnetic film with a uniform coercive force from the bottom layer to the top layer. In sputtering and vapor deposition methods,
Although it is possible to control the coercive blade by externally influencing the film growth during the growth of the magnetic film, the operation is extremely complicated and delicate. The blank 7ts-plating method usually yields a magnetic film whose coercive force value decreases as the magnetic giL thickness increases. In a magnetic recording medium using such a magnetic film, when recording is performed using a narrow gap length head for high recording density applications, the recording magnetic field near the gap of the magnetic head rapidly decreases as it moves away from the head surface in the perpendicular direction. Therefore, the geo-perlite characteristics, in which recording magnetization reversal becomes difficult, deteriorate significantly from the surface to the bottom of the magnetic film. In addition, in the upper layer of the magnetic film, a narrow magnetization transition region corresponding to high recording density is obtained, but as you go to the lower layer, recording becomes difficult and the magnetization transition width widens, making the magnetic film as a whole unsuitable for high-density recording. Become a medium.

According to Japanese Patent Publication No. 44-2888, in order to obtain a magnetic film with a laminated structure having a magnetic plating layer with high coercive force in the upper layer and a magnetic plating layer with low coercive force in the lower layer by electroless plating, the following steps are required. It is done in steps. That is, the substrate was treated with a baladium chloride solution pdc1.0.55 g/l! , 11c
z s me/l: ) for 1 minute, and then immersed in an electroless cobalt plating solution (a solution consisting of hypophosphorous acid, cobalt ions, etc.) Kpfr for the required time.

By repeating these two steps, a laminated film of a cobalt film and a varadinium film is formed, and the coercive force of the film is said to produce precipitates that increase with the thickness of the total magnetic layer.
However, according to additional experiments by the authors, in order to obtain a film with the desired characteristics, the management conditions of the parajucum chloride solution (concentration, 1 elapsed time after preparation, etc.) and the processing conditions for the parajucum chloride solution (temperature) ,time.

The range of conditions such as vibration (oscillation, etc.) was narrow, and reproducibility was extremely poor.Furthermore, the fabrication process was complicated by repeating the bulk treatment and cobalt plating, and the total thickness of the magnetic layer was thin. is difficult to apply. In addition, with this method, the value of coercive force changes stepwise in the film thickness direction, but since the change is discontinuous, there is a risk of problems such as distortion of reproduced waveforms and bit errors during recording and reproduction. There is.

The purpose of the present invention is to improve the conventional problems and to provide a magnetic recording medium in which the coercive force of the magnetic film increases continuously from the bottom surface of the magnetic film toward the surface of the magnetic film, and to stably produce the same. The purpose of this invention is to provide a method for producing rice cakes.

(Means for Solving the Problems) The magnetic recording body according to the present invention includes a magnetic film formed on a substrate, and the coercive force of the magnetic film is continuous from the bottom surface of the magnetic film toward the surface of the magnetic film. It is characterized by an increasing number of people.

The method for producing a magnetic recording medium according to the present invention includes an aqueous solution containing at least cobalt ions or cobalt ions and nickel ions as metal ions, and at least a reducing agent for the metal ions and a complexing agent for the metal ions as additives. At least a malonic acid group is included as a complexing agent for the metal ion, and the malonic acid group is 0.0
The method is characterized in that a magnetic film is formed by electroless plating using a solution added in a concentration range of O1 mat/l or more and 0.7 mn1/l or less.

The magnetic film used in the magnetic recording body of the present invention contains at least Co or Co and Ni, and further contains P,
The magnetic thin film contains at least one structure selected from B, or further contains at least one structure selected from Re, Mn, and W. Other components of the magnetic film used in the present invention.

Be, Mg, A4 au g S r g Fe g
Sr HYg Zr , Nb2 Cd g In e
Sb, Ta, Ir, Hg, Tl, Nb, G
d, Tb, Ti, V, Cr.

Cu, Zn, Oa, Oe, Mo, ah, pd
, Ag, Au, pt, Sn.

're, Ba, Ce, Sm, Os, Pb,
Bi and the like may be included within a range that does not affect the effects of the present invention. In addition to these elements, the plating film also contains C, N, O, S, As, and N depending on the type of additive.
The thickness of the magnetic film, which may contain non-metals such as a, K, F, C1, and Ca, is in the range of 0.05 to 5 μm, but is preferably 0.15 μm or less for high-density recording. The base material used to form the usually aluminum alloy, copper,
Although metal substrates such as brass, phosphor bronze, iron, and titanium are used, the present invention can also be applied to non-metal substrates such as glass and resin, or substrates made of composite materials of metal and non-metal, through appropriate activation treatment. The main purpose of the present invention is to provide a magnetic recording medium in which the coercive force of a magnetic film formed on a substrate increases continuously from the bottom of the magnetic film to the surface of the magnetic film. Therefore, it is clear that the present invention can also be applied to magnetic recording bodies having a structure in which additional layers of various materials are added to the upper and lower layers of the magnetic film for use in various applications. For magnetic recording bodies with such a structure, for example, the substrate can be formed by electroless plating, in order to obtain good polishability and a surface with minimal defects.
Intermediate layers such as reta nickel-phosphorus, nickel-copper-phosphorus, copper, tin, copper-tin, etc. layers fabricated by 4-layer plating, vapor deposition, sputtering, etc., and alumite layers fabricated by anodic oxidation) f! Those coated with chromium, molybdenum, titanium, gold, silver, platinum, palladium, etc. under the magnetic film for the purpose of controlling the magnetic properties of the magnetic film. Those with a pre-treatment layer of , palladium, tin-palladium, gold, etc., those with a soft magnetic layer formed under the magnetic film to increase the recording and reproducing sensitivity in perpendicular magnetic recording, and those with a soft magnetic layer formed under the magnetic film to provide weather resistance and durability. A protective layer and a lubricating layer are formed on the magnetic film (7) The main components of the l#cm plating bath used in the manufacturing method of the present invention include at least cobalt ions or cobalt as metal ions. In an aqueous solution containing ions and nickel ions and containing at least a reducing agent for the metal ions and a complexing agent for the metal ions as additives,
Although at least a malonic acid group is included as a complexing agent for the metal ion, pi (buffer, brightener, smoothing agent, stimulant, anti-pinhole agent, surfactant, Additives such as these may be used.

Cobalt ions, nickel ions, and soluble salts of cobalt or nickel, such as sulfates, chlorides, acetates, are dissolved in the electroless plating bath. The concentration of cobalt ions used is in the range of 0.005 to 1 mo//z, preferably 0.01 to 0.18 m
o The concentration of nickel ions in the range of I/l is
A range of 0.001 to 1 moJ//' is used,
Preferably it is in the range of 0.003 to 0.15 +nob. The metal ions used in the present invention include:
Co4TabaNi is the main component, but Re, Mn, W
It may contain at least one selected from the following.

Rhenium ions are supplied by soluble salts such as potassium perrhenate and ammonium perrhenate, and the m degree used is in the range of 0.0001 to 0.2 mat/l, preferably 0.001 ~0.05 mol/l
The manganese ion is supplied by a soluble salt such as manganese sulfate, chloride, acetate, etc., and the concentration range is from 0.001 to 1 mat/l, but preferably 0.001 to 1 mat/l. It is in the range of 01 to 0.05 mol/l. For tungsten, tungstate ions are often used and are supplied by soluble salts of tungstate such as sodium tungstate and potassium tungstate, with concentrations ranging from 0.003 to 1%.
mat/l range is used, preferably 0.0
It is in the range of 0.05 to 0.2 mopil. Also, a small amount of B
e, Mg, A/, 几11. St, Fe, Sr, Y,
Zr, Nb, Cds In.

8b, 'I''a, Ir, Hg, Tl, Nb,
Gd, Tb, Ti, V, Cr, Cu.

Zng Ga, Ge, Mo, 几り, Pd Ag, Au,
Pt, an, TetBa, Ce, am, Os,
Pb, Bi'4 (may contain D ions,
These ions are supplied by their respective soluble salts.

As a reducing agent, one or more of #-i, % hypophosphite, hydrogenated boronate compound, hydrazine, dimethylamine borane, and their derivatives are used in a range of 0.01 to 0.8
mol/l, preferably 0.05-0.3 mat/
It is used in the range of l.

At least malonic acid groups are used as complexing agents. The malonic acid group has 0.0 malonic acid or a soluble salt of malonic acid.
It is used in the range of 0.01 to 0.7 mol/l, but 0.01 to 0.7 mol/l is used.
A range of 1 to 0.6 mol/l is preferred. In addition, complexing agents include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, glutaric acid; fumaric acid, citraconic acid, glycolic acid, diglycolic acid, thioglycolic acid, pyruvic acid, lactic acid, oxalic acid, and succinic acid. , mercaptosuccinic acid, mandelic acid, malonic acid, maleic acid, itaconic acid, phthalic acid,
Carboxylic acids such as malic acid, salicylic acid, tartaric acid, tartronic acid, ascorbic acid, citric acid, sulfosalicylic acid, benzoic acid, amines and their derivatives such as ethylenediamine, diethylenetriamine, triethylenetetocyamine, pyridine, iminodiacetic acid, iminodipropionic acid ,
Aminopolycarboxylic acids such as nitrilotriacetic acid, nitrilotripropionic acid, ethylenediaminediacetic acid, ethylenediaminetetraacetic acid, ethylenediaminetetrapropionic acid, diethylenetriaminepentaacetic acid, alanine, colloid: 7, /< rif, norleucine, tyrosine, cysteine, glutamic acid, One or more of amino acids such as glycine, aspartic acid, asparagine, weak acids such as hexonic acids such as allonic acid, itonic acid, galactonic acid, gluconic acid, gulonic acid, gulonic acid, mannonic acid, etc., or their soluble salts. A combination of these complexing agents may be used at a concentration of 0.02 to 2.
A range of Omol/l is used, 0.1 to Q, 9mol
A range of 7 is preferred.

As the pH buffering agent, ammonium salts, carbonates, organic acid salts, etc. are used, and ammonium sulfate, ammonium chloride, boric acid, etc. are preferably used.

The concentration range is 0.01 to 3 mo17, preferably 0.0
3 to 1 moθt is used.

As a pH adjuster, ammonia or caustic alkali such as NaOH, LiOH, KOf(, RbOH, CsO
H.

FrOH, Be(OH)2. Mcr(OH)ty C
a(OH)2.5r(OH),.

Metal hydroxides such as Ba(OII)t and a(OH) are used singly or in combination of two or more.

Normally, the plating solution before bath preparation without the addition of a pH adjuster is approximately neutral to acidic, and is adjusted to alkalinity (pi) by adding the above-mentioned hydroxide. Acids such as hydrochloric acid, sulfuric acid, nitric acid, and acetic acid are used.P
The H range used is between 3 and 14.5, preferably between 8.5 and 11.5.

(Function) By providing a magnetic film with a high coercive force in the upper layer of the magnetic film and a magnetic film with a relatively low coercive force such that recording magnetization reversal occurs even in a weak head magnetic field in the lower layer of the magnetic film, Attempts have been made to create a magnetic recording medium suitable for high-density recording, but with conventional methods, the value of coercive force changes in the film thickness direction, but because the change is discontinuous, the playback waveform during recording and playback is This may cause problems such as distortion and bit errors. Therefore, in the present invention, a magnetic recording medium,
These problems are solved by continuously increasing the coercive force of the magnetic film from the bottom of the magnetic film toward the surface of the magnetic film. In order to obtain such a magnetic recording body, it is advantageous to produce the magnetic film by electroless plating.

Complexing agents play an important role in electroless plating. The complexing agent forms a complex with metal ions in the plating bath and controls the progress of the plating reaction. Although the relationship between the complexing agent and the magnetic properties has not been theoretically clarified at present, it is thought that by selecting the complexing agent, it is possible to change the coercive force along with the film thickness. For this reason, the inventors extensively investigated various complexing agents, and found that the coercive force was continuous (increased) from the bottom to the surface. It was also found that the dependence of the coercive force on the film thickness can be changed by selecting the concentration of malonic acid groups.The present invention is based on the findings obtained. This was brought about by

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples.

(Comparative Example 1) A non-magnetic tooth-P layer was plated on an aluminum alloy substrate with an inner diameter of 100 mm and an outer diameter of 210 mm, and after the surface was mirror-polished, a film thickness of 0.4 μm was applied using the following plating bath and plating conditions.
Cobalt sulfate 0.06 mol/l Cobalt sulfate 0.06 mol/l
Nickel sulfate 0.08 mat/l
Ammonium perrhenate 0.003 mat71
Sodium hypophosphite 0.2 mol/l
-Sodium ronate 0.85 mat/
l Sodium tartrate 0.25 mat/
l tart o :/ HO, 035 mol/l sodium gluconate Q, 2 mat/'l! Ammonium sulfate 0.5 mat/l plating conditions (11 Bath temperature 80 degrees C plating bath p) 1 9.2 (voice adjusted with ammonia water at room temperature) Plating solution volume 1001 Next, on top of this, silicon V - is spin-coated and baked at 190 degrees C for several hours to form a protective film mainly composed of silicic acid polymer with a film thickness of 0.02 μm, and on top of this a protective film consisting of an aliphatic hydrocarbon-based solid lubricant. A magnetic disk was fabricated by forming a lubricating layer. The obtained magnetic disk is referred to as disk A.

The film thickness dependence of the coercive force of the magnetic film thus obtained is expressed as
As shown in the figure. Since this magnetic film has perpendicular anisotropy, the coercive force in the direction perpendicular to the film surface is shown in the figure.
Hc in μm is 13200e, but it decreases as the plating film thickness increases, and Hc at a plating film thickness of 0.4 μm is 790e.
At 0e, the coercive force decreased continuously from the bottom to the surface.

(Comparative Example 2) A magnetic recording body was produced using the same procedure as Comparative Example 1, but in this comparative example, a Co-P alloy magnetic film with a film thickness of 0.1 μm was formed using the following plating bath and plating conditions. was formed.

Plating bath (2) Cobalt chloride 0.03 mo171
Sodium hypophosphite 0.05 mat/l
Sodium citrate 0.10 mat/l
Ammonium chloride 0.3 mol/l
Plating conditions (2) Bath temperature 80 degrees C Plating bath pl-18,2 (adjusted with NaOH at room temperature) Plating solution capacity 1001 The obtained magnetic disk is referred to as disk B.

The film thickness dependence of the coercive force of the magnetic film obtained in this way is expressed as
As shown in the figure. Since this magnetic film has in-plane anisotropy, the magnetic force in the film plane is shown in the figure.Hc for an O-plated film thickness of 0.02 μm is 11400e, but it decreases as the plated film thickness increases. Hc at a film thickness of 0.18 μm is 3600e
(Example 1) A magnetic recording medium was produced using the same procedure as Comparative Example 1, but in this example, the following plating was used. A Co-Ni-Re-P alloy magnetic film with a film thickness of 0.4 μm was formed using the bath and plating conditions.

Plating bath (3) Cobalt sulfate 0.06 mat/l
#C nickel acid 0.08 mat
/l ammonium perrhenate 0. OO3mat7
Sodium hypophosphite 0.2 mat/
l Sodium malonate 0.30 mol/
l Sodium tartrate 0.25 mat/
l tartronic acid 0.035 ma
t/l sodium gluconate 0.3 mo
Ammonium sulfate 0.5 ma
t/l plating conditions (3) Bath temperature 80 degrees C Plating bath -49.2 (pH adjusted with ammonia water at room temperature) Plating solution volume 'M 1001 The obtained magnetic disk is referred to as disk C.

The film thickness dependence of the coercive force of the magnetic film thus obtained is shown in FIG. Since this magnetic film has perpendicular anisotropy, the coercive force in the direction perpendicular to the film surface is shown in the figure.

Hc for a plating film thickness of 0.05 μm is 2900e,
Plating film thickness increases with increase of plating film thickness: 0.4μm
(Hc was 10,500e), and a magnetic film was obtained in which the coercive force increased continuously from the bottom surface to the surface.

(Example 2) A magnetic recording body was produced in the same manner as in Comparative Example 1, but in this example, a Co-N1-Re- Plating bath in which P alloy magnetic film was formed (4) Cobalt sulfate 0.06 mol Nickel sulfate 0.08 mol/l Ammonium perrhenate 0.003 mat71 Sodium hypophosphite 0.2 mat/l Malonic acid Sodium 0.50 ma! /l Sodium tartrate 0.25 moゎt Tartronic acid 0.035 mat/l Sodium gluconate 0.3 mat/l Sodium sulfate/Monium 0.5 mat/l Plating conditions (4) Bath temperature 80 degrees C Plating M pi4 9.2 (adjusted with ammonia water at room temperature) plating solution '8-n 10 (D') The obtained magnetic disk is referred to as disk D.

FIG. 2 shows the film thickness dependence of the coercive force of the magnetic film thus obtained. Since this magnetic film has perpendicular anisotropy, the coercive force in the direction perpendicular to the film surface is shown in the figure.

He with a plating film thickness of 0.05 μm is 5100e, but
The plating film thickness increased to 0.3 μm as the plating film thickness was requested.
As shown in Comparative Example 1 and Examples 1 and 2, the I4c of malonic acid is 1o000e. By selecting i, the film thickness dependence of the coercive force can be changed.

(Example 3) A magnetic recording medium was prepared in the same manner as in Comparative Example 1; however, in this example, a Co-Ni film with a film thickness of 0.4 μm was prepared using the following plating bath and plating conditions. Plating bath with e-Mn-P alloy magnetic film formed (5) Cobalt sulfate 0.06 mat/l
Nickel sulfate 0.12 mat/
1 Manganese sulfate 0.04 mat/
1 Ammonium perrhenate 0.005 mol
/ Sodium hypophosphite 0.3 mol
/l Sodium malonate Q, 3 moe/
l Sodium tartrate 0.2 mol/l
Sodium succinate 0.3 mat/
Ammonium 1 sulfate 0.5 mat/l
Plating conditions (5) Bath temperature 80 degrees C μ of plating bath (9,2 (adjusted with ammonia water at room temperature) Capacity of plating solution 1001 The obtained magnetic disk is referred to as disk E.

The film thickness dependence of the coercive force of the magnetic film thus obtained is shown in FIG. 3. Since this magnetic film has perpendicular anisotropy, the coercive force in the direction perpendicular to the film surface is shown in the figure.

Hc of plating film thickness 0.05 μm is 3700e,
Plating film thickness increases with increase of plating film thickness: 0.4μm
Hc was 10100e, and a magnetic film was obtained in which the coercive force increased continuously from the bottom surface to the surface.

(Example 4) A magnetic recording medium was prepared in the same manner as in Comparative Example 1, but in this example, 1n of Co-Ni- was coated with a film thickness of 0.4 μm using the following plating bath and plating conditions. -P alloy magnetic film was formed.

Plating bath (6) Cobalt sulfate 0.045 mat/l
Sulfur 61 2y Kel 0.01 mat
/l manganese sulfate 0.03moe71
Sodium hypophosphite 0.2 mat/l
Malo/Sodium acid 0.7 Sodium malate 0.05 mat/l
Ammonium sulfate 0.45 mat/l
Plating conditions (6) Bath temperature 80 degrees C Plating bath pi4 9.5 (adjusted with ammonia water at room temperature) Plating solution volume 1001! The obtained magnetic disk is referred to as disk F.

FIG. 4 shows the film thickness dependence of the coercive force of the magnetic film thus obtained. Since this magnetic film has perpendicular anisotropy, the coercive force in the direction perpendicular to the film surface is clearly shown in the figure.

The Hc of the plating film thickness of 0.05 μm is 5400e, but
Plating film thickness increases with increasing plating film thickness: 0.4μm
He was 9200e, and a magnetic film was obtained in which the coercive force increased continuously from the bottom to the surface. (Example 5) A magnetic recording medium was prepared in the same manner as in Comparative Example 1. However, in this example, a Co--Mn--P alloy magnetic film with a thickness of 0.4 μm was formed using the plating bath and plating conditions described below.

Plating bath (7) Cobalt sulfate 0.06 mat/l
Manganese sulfate 0.04 mat71
Sodium hypophosphite 0.2 mat/l
Sodium malonate 0.4 mat/l
Sodium malate 0.4 mol/
Ammonium l'AE acid 0.4 ma
t/l plating conditions (power bath temperature 8o C plating bath pH 9.2 (at room temperature, ammonia water p+ (
Adjustment) Capacity of plating solution: 1 oz The obtained magnetic disk is referred to as disk G.

The film thickness dependence of the coercive force of the magnetic film thus obtained is shown in FIG. Since this magnetic film has perpendicular anisotropy, the coercive force in the direction perpendicular to the film surface is shown in the figure.

He with a plated film thickness of 0.05 μm is 5100e, but
As the plated film thickness increases, Vr-increases with plated film thickness 0.4
Hc in μm was 8500e) A magnetic film was obtained in which the % retention force increased continuously from the bottom to the surface (Example 6) Magnetic recording was performed using the same procedure as in Comparative Example 1. In this example, a Co-W-P alloy magnetic film with a film thickness of 0.4 Am was formed using the plating bath and plating conditions described below.

Plating bath (8) Sulfur (i cobalt 0.1 mat/
l Sodium tungstate 0.18 mo17
Sodium hypophosphite 0.35 mat/
l Sodium malonate 0.25 mol/l Gluconic acid 0.6 mat/l Ammonium sulfate 0.35 mol/l Plating conditions (8) Bath temperature 80° C Adjustment) Plating solution capacity 1001! The obtained magnetic disk is referred to as disk H. The film thickness dependence of the coercive force of the magnetic film thus obtained is shown in FIG. Since this magnetic film has perpendicular anisotropy, the coercive force in the direction perpendicular to the film surface is shown in the figure.

Hc of plating film thickness 0.05μ[n is 5800e, but increases as plating film thickness increases, and plating film thickness 0.4μ
What is Hc at m? 900e, and a magnetic film in which the coercive force increases continuously from the bottom surface to the surface was obtained. In this example, a Co--Ni--P alloy magnetic film with a thickness of 0.1 μm was formed using the plating bath and plating conditions described below.

Plating bath (9) Cobalt sulfate 0.08 mat/l
! sulfur rfJt nickel 0.02 m
at/l sodium hypophosphite 0.15 m
ol/l sodium malonate 0.3 m
ol/l sodium glutamate 0.6 m
nl/l ammonium sulfate Q, 4 m
nl/l plating conditions (9) Bath temperature 80 degrees C Plating bath -9.0 (voice adjusted with ammonia water at room temperature) Plating solution volume 100I! The obtained magnetic disk is referred to as disk I.

FIG. 7 shows the film thickness dependence of the coercive force of the magnetic film thus obtained. Since this magnetic film has in-plane anisotropy, the in-plane coercive force is shown in the figure. He with a plating film thickness of 0.02μm
HC is 5400e, but increases as the plated film thickness increases, and at a plated film thickness of 0.18 μm, HC becomes 9500e, and a magnetic film in which the coercive force increases continuously from the bottom to the surface can be obtained. Ta.

(Example 8) A magnetic recording body was produced using the same procedure as in Comparative Example 1, but in this example, Co-Ni-W-P with a film thickness of 0.1 μm was used using the following plating bath and plating conditions. An alloy magnetic film was formed.

Meliki bath 0α cobalt sulfate 0.1 ma! /l
Sulfur 02K 0.02 mnl/l
Sodium tungstate 0.04 mat71
Sodium hypophosphite 0.2 mol/l
Sodium malonate 0.6 mnl/l
Sodium gluconate 0.2 ml/l
Sulfuric ammonium 0.5 mnl/l
Plating conditions u1 Bath vJA 80 degrees C Plating bath -19,2 (p11 with ammonia water at room temperature
Adjustment) Capacity of plating belly 1007? The obtained magnetic disk is referred to as disk J.

FIG. 8 shows the film thickness dependence of the coercive force of the magnetic film thus obtained. Since this magnetic film has in-plane anisotropy, the coercive force in the film plane is 4600e for a 0-plated film thickness of 0.02 tim shown in the figure, but it increases as the plated film thickness increases. At a film thickness of 0.18 μm, the He value was 8100e9, and a magnetic film in which the coercive force increased continuously from the bottom surface to the surface was obtained.

(Example 9) A magnetic recording medium was produced in the same manner as in Comparative Example 1, but in this example, a co-e-P alloy with a film thickness of 0.1 μm was coated using the following plating bath and plating conditions. A magnetic film was formed.

Plating bath aυ Cobalt sulfate 0.06 mnl/l
Ammonium perrhenate 0.002 mat71
Sodium hypophosphite 0.2 moθt Sodium malonate 0.3 mnl/l Sodium tartrate 0.5 mol/l
l Ammonium sulfate 0.3 ml/
l Plating conditions aυ Bath temperature 80 degrees C Plating bath P) 1 9.1 (voice adjusted with ammonia water at room temperature) Plating solution volume 1001! The obtained magnetic disk is made into a disk.

The film thickness dependence of the coercive force of the magnetic film thus obtained is shown in FIG. 7.Since this magnetic film has in-plane anisotropy, the in-plane coercive force is shown in the figure. H with plating film thickness of 0.02 μm
e is 4500e, but Hc increases as the plated film thickness increases, and at a plated film thickness of 0.18 μm, Hc is 7300e. Obtained 〇 (Example 10) A magnetic recording body was produced in the same manner as in Comparative Example 1, but in this example, a Co- Plating bath a2 with P alloy magnetic film formed Cobalt sulfate 0.07 mat71
Sodium hypophosphite 0.25 mat/l
Sodium malonate A O,001mat/l
Sodium tartrate 0.4 mat/l
Ammonium sulfate 0.6 mokt Plating conditions cLz Bath temperature 80 degrees C Plating bath pH 9,0 (adjusted with ammonia water at room temperature) Plating solution volume 100I! The obtained magnetic disk is referred to as disk L.

The film thickness dependence of the coercive force of the magnetic film obtained in this way is expressed as
As shown in the figure. Since this magnetic film has in-plane anisotropy, the coercive force in the film plane is shown in the figure.
e is 5000e, but Hc increases as the plating thickness increases, and at a plating thickness of 0.18 μm, Hc is 6900e, resulting in a magnetic film in which the coercive force increases continuously from the bottom to the surface. It was done.

The recording and reproducing characteristics of the magnetic disks obtained in the above comparative examples and examples were measured under the following conditions.Measurement conditions Head used: Mn-Zn7 elite head Rad gap length 0.3 μm Head flying height 1k 0.15 μm Override characteristics are disks A and C1D.

Regarding E%F and G%H, when first recording at 20kFRPI and then recording at K40kPrtPI, the 20kFRPI component as residual noise and the 40kFRPI component as a signal are recorded.
0 disc B% measured as the ratio of kFRPI components
I, J%K.

For L, first record at 15 kFRPI, then at 3
1 as residual noise when recording at 0 kFRPI
It was measured as the ratio of the 5 kFRPI component to the 30 kFRPI component as a signal. In addition, the limit recording density D50 of each magnetic disk (as a guideline for recording density, we have determined the record that the reproduction output is 1/2 of the solitary wave reproduction output) Table 1 shows the measurement results for disks A%C, D%E, F, G, and H.Compared to disks whose coercive force decreases as the film thickness increases, The recording and reproducing characteristics of disks C, D, E, F, G, and H improved as the film thickness increased and the coercive force increased by lQ+.

Table 2 shows the measurement results for %L on disks B, I, and J. Disk whose coercive force increases with increase I% Jl K, L
The recording and playback characteristics have been improved.

(Effects of the Invention) As shown above in the comparative examples and examples, according to the present invention, in a magnetic recording body consisting of a magnetic film formed on a substrate, the coercive force of the magnetic film is By making the magnetic recording body continuously increasing from the bottom surface toward the surface of the magnetic film, a magnetic recording body suitable for high-density recording with excellent override characteristics can be obtained. Further, according to the method for manufacturing a magnetic recording medium of the present invention, at least cobalt ions or cobalt ions and nickel ions are included as metal ions, and at least a reducing agent for the metal ions and a complexing agent for the metal ions are included as additives. An electroless plating bath is used in which the aqueous solution contains at least a malonic acid group as a complexing agent for the metal ion, and the malonic acid group is added in a concentration range of 0.001 moφ or more and 0.7 mat/l or less. In particular, it is possible to stably obtain a magnetic film in which the coercive force increases continuously from the bottom to the surface.

[Brief explanation of drawings]

Figures 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 are examples 1 and 2.3%, respectively. 4.5.6.7.8.9 and 10 are diagrams showing how the coercive force of the magnetic film obtained by the method of manufacturing a magnetic recording body of the present invention changes with the plating film thickness. FIG. 11 and FIG. 12 are diagrams showing similar relationships for magnetic films obtained from the electroless plating baths used in Comparative Examples 1 and 2, respectively. 1 (51,1・“, 71V ° − arc・11′
; jh', mouth-to-mouth. Figure 3 Film thickness (μm) 0 0, + 0.2 0.3 0.4
0.5 film, thickness (μm) 5th port 0 0. + 0.2 0.3 0.
4 0.5″i7 Diagram Square 9 Film Thickness (μm) Film Thickness (μm) 110th Film Thickness (pm) Film Thickness (μm)

Claims (4)

[Claims] (1) A magnetic recording body having a magnetic film formed on the base, characterized in that the coercive force of the magnetic film increases continuously from the bottom surface of the magnetic film toward the surface of the magnetic film. magnetic recording medium. (2) The magnetic film contains at least Co or Co and Ni, and further contains at least one selected from P and B.
The magnetic recording medium according to claim 1, which is a magnetic thin film containing seeds. (3) The magnetic film contains at least Co or Co and Ni, and further contains at least one selected from P and B.
Claim 1, which is a magnetic thin film containing seeds and further containing at least one selected from Re, Mn, and W.
Magnetic recording medium described in Section 1. (4) In an aqueous solution containing at least cobalt ions or cobalt ions and nickel ions as metal ions, and containing at least a reducing agent for the metal ions and a complexing agent for the metal ions as additives, at least as a complexing agent for the metal ions. A magnetic film is formed by electroless plating using a solution containing malonic acid groups and to which the malonic acid groups are added in a concentration range of 0.001 mol/l to 0.7 mol/l. A method for manufacturing a magnetic recording medium.