JPH0457746B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a plating bath for producing a magnetic recording medium (magnetic film) used for so-called perpendicular recording, in which recording is performed by magnetization in the film thickness direction of the magnetic recording medium. (Prior Art) Conventionally, in magnetic recording devices such as general magnetic disk devices and magnetic tape devices, recording is performed by horizontally magnetizing a magnetic recording medium formed on a substrate using a ring-shaped magnetic head. It's summery. However, in recording using horizontal magnetization, as the wavelength of the recording signal becomes shorter, that is, as the recording density increases, the demagnetizing field within the medium increases, causing attenuation and rotation of the residual magnetization, resulting in a significant decrease in the reproduction output. There is a drawback. To solve this problem, a perpendicular recording method was proposed in which the demagnetizing field becomes smaller as the wavelength becomes shorter.A magnetic recording medium suitable for this perpendicular recording has an axis of easy magnetization perpendicular to the film thickness. A sputtered Co-Cr film has been proposed. It has been reported that this perpendicular magnetization recording method is superior to the conventional recording method using horizontal magnetization in high-density recording. (Unexamined Japanese Patent Publication No. 52-134706
(see publication). By the way, when a Co--Cr film is produced by sputtering, there is a problem in mass production because it is carried out in a vacuum system. For this reason, electroless Co-Mn- which manufactures a magnetic recording medium with an axis of easy magnetization perpendicular to the film surface by an electroless plating method that improves these manufacturing problems and is excellent in mass production. P-metal baths have been discovered (Patent Application No. 1983-025833, (Special Publication No. 38432-1981)),
“Electroless plating bath”). Generally, the condition for easy magnetization in the direction perpendicular to the film surface is the perpendicular anisotropic magnetic field of the medium.
There is a relationship between Hk and the maximum value 4πMs of the demagnetizing field (Ms is saturation magnetization) of Hk>4πMs or Hk/4πMs>1. Although it is not necessary to satisfy this condition for perpendicular recording media, Hk/4πMs
Even if it is 1, the larger the value, the closer it is to the conditions for easy perpendicular magnetization, so it can be said that it is preferable as a medium characteristic. This tendency is also shown by the results of measuring recording density characteristics using actual recording media. For example, IEICE technical research report, MR82
-22, October 15, 1982, Co-V with various characteristics
Perpendicular recording is performed on a sputtering medium using a _ring head.
This shows that the value representing the recording density performance of the medium) increases, and that D ₅₀ decreases rapidly when the Hk/4πMs value falls below 0.5. This tendency holds true even when the types of media and recording/reproducing conditions are different. However, in the electroless plating bath, a
Although a magnetic film in which -Co hexagonal crystals (easy axis of magnetization) are oriented perpendicular to the substrate can be obtained, the saturation magnetization Ms decreases little and the value of 4πMs becomes extremely large, which becomes an obstacle to perpendicular magnetization recording. For this purpose, by eutectoiding nickel (Japanese Patent Application 1982-155706, (Patent Publication No. 3-62794), "Electroless Plating Bath"), and by eutectoiding rhenium in addition to nickel (1982
The following is a bath published in Abstracts of the 66th Academic Conference of the Metal Surface Technology Association, P. 8-9 in 2013.
(called AT bath) is designed to reduce Ms. However, when rhenium ions are added to the electroless plating bath in order to eutectoid rhenium on the Co-Ni-Mn-P magnetic film, the plating bath becomes significantly unstable in the AT bath using sodium tartrate as a complexing agent. However, there were problems such as non-uniformity of magnetic properties, dependence on the underlying substrate, and deterioration of reproducibility. When producing a magnetic recording medium such as a magnetic disk using an AT bath, the uniformity of the reproduction output waveform (envelope) for one round decreases due to the non-uniformity of the magnetic properties, resulting in poor reproducibility of the magnetic properties and the lifespan of the bath. Because of the short length, there were drawbacks such as the fact that only a very limited amount could be obtained from a constant force plating bath. Also, the magnetic properties are more dependent on the substrate when using a metal substrate than on a polyimide substrate coated with a Pd catalyst.
There was a problem that Hk/4πMs decreased significantly. (Objective of the Invention) The object of the present invention is to improve the above conventional problems and to provide an electroless medium that can stably produce a magnetic recording medium having uniform properties suitable for magnetic recording in a direction perpendicular to the film surface. The purpose is to provide a soaking bath. (Structure of the Invention) The electroless plating bath according to the present invention contains at least cobalt ions, nickel ions, manganese ions, and rhenium ions as metal ions, and at least a reducing agent for these metal ions, a PH buffer, and a PH regulator as additives. It is characterized in that at least a malonic acid group, a tartaric acid group, and a tartronic acid group are simultaneously added to the aqueous solution containing the metal ion as a complexing agent. (Description of the Structure of the Invention) The present inventors conducted a detailed study on the plating bath composition in order to improve the above-mentioned problems, and as a result, the following became clear. In an AT bath that uses sodium tartrate as the sole complexing agent, it is easy to increase the amount of rhenium eutectoid, but it is difficult to stably eutectoid the appropriate amount of rhenium and nickel into the plated film. It is not possible to obtain a film with uniform characteristics with good reproducibility. Although Ms decreases significantly, Hk also decreases significantly. Depending on the substrate, Hk/4πMs decreases significantly. When sodium malonate is used alone as another complexing agent, Hk has a large value even if rhenium is increased, but Ms does not decrease much. Therefore, Hk/4πMs takes a small value. Therefore, a bath containing both tartaric acid and malonic acid was considered, but it was difficult to take advantage of the characteristics of both to obtain desirable magnetic properties. However, when tartronic acid is further added to this, it acts effectively on malonic acid and tartaric acid, and Ms.
Preferred magnetic properties can be obtained by appropriately reducing the value of . In addition, by simultaneously containing malonic acid, tartaric acid, and tartronic acid in the plating bath, the metal ion concentration in the bath is appropriately adjusted through the interaction of these complexing agents, which contributes to the stability of the plating bath. I found out. The present invention has been made based on this knowledge. According to the present invention, the metal ions in the plating bath are appropriately adjusted and the composition of the plating film is kept constant, thereby stabilizing the bath and improving and making the film properties uniform. Cobalt ions, nickel ions, and manganese ions used as metal ions in the present invention can be obtained by dissolving soluble salts of cobalt, nickel, or manganese such as sulfates, chlorides, and acetates in an electroless plating bath. supplied. The concentration of cobalt ion is 0.005 to 1 mol/
is used, preferably 0.01 to
It is in the range of 0.15 mol/. The concentration of nickel ions used is in the range of 0.001 to 0.5 mol/, preferably in the range of 0.005 to 0.20 mol/. The concentration of manganese ions is preferably in the range of 0.003 to 2 mol/, but preferably in the range of 0.02 to 0.2 mol/. Rhenium ion is potassium perrhenate,
Provided by soluble salts such as ammonium perrhenate, rhenium ion concentrations range from 0.0001 to
A range of 0.1 mol/, preferably 0.001 to 0.05 mol/ is used. Hypophosphites are commonly used as reducing agents, but hydrazine salts, borohydrides, dimethylamine borane or derivatives thereof, etc. can also be used. Ammonium salts, carbonates, organic acid salts, etc. are used as the PH buffer, and the concentration ranges from 0.01 to 2 mol/. As a pH regulator, an alkali such as ammonium or sodium hydroxide is used to increase the pH, and an acid such as sulfuric acid or hydrochloric acid is used to decrease the pH. The malonic acid group as a complexing agent is supplied by malonic acid or a soluble salt of malonic acid, with a range of 0.05 to
Concentrations in the range 2.5 mol/are used. The tartaric acid groups are provided by tartaric acid or soluble salts of tartaric acid, and concentrations in the range of 0.02 to 1.5 mol/l are used. The tartronic acid group is supplied by tartronic acid or a soluble salt of tartronic acid, and
Concentrations in the range 1.0 mol/are used, preferably in the range 0.01-0.3 mol/. In particular, tartronic acid has a remarkable effect on the stable precipitation of each metal ion, and is therefore characterized in that a sufficient effect can be obtained by adding a small amount compared to other complexing agents. Further, the electroless plating bath of the present invention has little dependence on the substrate, so it can be applied to various metal or non-metal substrates. Hereinafter, the features of the electroless plating bath according to the present invention will be explained using comparative examples and examples. (Comparative example) A non-magnetic Ni-P layer was plated on an aluminum alloy substrate with an inner diameter of 100 mm and an outer diameter of 210 mm, and a Co-Ni layer with a thickness of 0.5 μm was applied on top of the non-magnetic Ni-P layer using the following plating bath and plating conditions.
A Mn-Re-P alloy magnetic film was formed. Plating bath (1) Cobalt sulfate 0.06mol/ Nickel sulfate 0.04mol/ Manganese sulfate 0.03mol/ Ammonium perrhenate 0.003mol/ Sodium hypophosphite 0.2mol/ Ammonium sulfate 0.5mol/ Sodium tartrate 0.5mol/ Plating conditions Plating Bath PH9.2 (PH adjusted with NH ₄ OH at room temperature) Plating bath temperature 80℃ Next, spin-coat silicic acid monomer on top of this,
C. for several hours to form a protective film with a thickness of 0.02 μm mainly composed of a silicic acid polymer. When the recording and reproducing characteristics of the thus obtained magnetic disk were measured under the following conditions, D ₅₀ =
Obtained a value of 30KFRPI. Measurement conditions Head used Mn-Zn ferrite ring head Head gap length 0.3μm Head flying height 0.2μm However, the playback output for one revolution is 1/1 of the maximum value.
There are more than 25% of the entire cycle where the value is 2 or less.
There was a practical problem with the uniformity of the envelope. The medium characteristic of the part of the envelope where the output is maximum was Hk/4πMs value of 0.6,
At the point where the output was 1/2, it was less than 0.5, indicating non-uniformity of characteristics. The life of the plating bath was investigated as follows. At a constant plating solution (volume 100),
Twenty magnetic disks were plated per day in the same manner as in the procedure described above for this comparative example, and the relationship between the number of plated disks and the magnetic properties was investigated. Metal salts and reducing agents are
Each ingredient was replenished in an amount equivalent to the consumed amount on each plating day.
Figure 1 shows the change in Hk/4πMs for every 20 plated sheets. The value of Hk/4πMs at the start of plating is 0.6, but decreases as the number of sheets plated increases to 60
The value of Hk/4πMs at the end of plating is
0.5, and as the number of plated sheets increases further, Hk/
The value of 4πMs decreased further. If the value of Hk/4πMs that is practically acceptable as a storage medium is 0.5 or more,
It can be seen that the number of magnetic disks obtained from the plating bath (1) (hereinafter referred to as bath life) is only about 60 plated disks. The composition of the makeup bath (1) was selected to be the most preferable in terms of bath stability. In AT baths, the concentrations of ammonium perrhenate and sodium tartrate most affect the stability and magnetic properties of the bath. Ammonium perrhenate is 0.001mol/
If it is below, Ms is too large, and if it is 0.008 mol/ or more, the plating rate decreases and uniform precipitation is extremely difficult, so 0.003 mol/ is most preferred. If the concentration of sodium tartrate is less than 0.25 mol/, bath decomposition will easily occur, and if it is more than 0.75 mol/, uniform precipitation will be difficult and the bath life will be shortened, resulting in poor stability.
0.5 mol/was most preferred. Although the plating bath (1) has a preferable composition among the A-T baths,
As shown in this comparative example, there were problems with stability and magnetic properties. (Example 1) A magnetic disk was produced in the same manner as in the comparative example, but the following plating bath was used in this example. Plating bath (2) Cobalt sulfate 0.06mol / Nickel sulfate 0.08mol / Manganese sulfate 0.03mol / Ammonium perrhenate 0.003mol / Sodium hypophosphite 0.2mol / Ammonium sulfate 0.5mol / Sodium malonate 0.3mol / Sodium tartrate 0.2mol / Tartronic acid 0.05 mol / The recording and reproducing characteristics of the thus obtained magnetic disk were measured under the same conditions as in the comparative example.
The value of D ₅₀ = 52KFRPI was calculated. Regarding the playback output for one round, there was no part where the playback output was less than 90% of the maximum value, indicating a sufficiently good envelope for practical use. The media characteristics within one surface of the disk are also uniform, and the average value Hk/
The variation was within ±0.05 for 4πMs=1.75. As a result of examining the life of the plating bath in the same manner as in the comparative example, Figure 2 was obtained as the change in Hk/4πMs depending on the number of plated sheets. The value of Hk/4πMs at the start of plating is 1.75, and decreases as the number of sheets plated increases, but it is still 1.5 at the end of plating 220 sheets.
Therefore, the degree of decrease is small. After that, the degree of decrease increases, but Hk/4πMs becomes 0.5 when the number of sheets plated is 340. In this example, by using a aging bath using sodium malonate, sodium tartrate, and tartronic acid as complexing agents, a large number of magnetic disks with significantly better and more uniform medium characteristics and recording density characteristics than in the comparative example were produced. I was able to get it. (Example 2) A magnetic disk was produced in the same manner as in the comparative example, but the following plating bath was used in this example. Plating bath (3) Cobalt sulfate 0.06mol / Nickel sulfate 0.10mol / Manganese sulfate 0.01mol / Ammonium perrhenate 0.004mol / Sodium hypophosphite 0.2mol / Ammonium sulfate 0.4mol / Sodium malonate
0.1, 0.2, 0.3, 0.4, 0.5, 0.07 mol / Sodium tartrate 0.2 mol / Tartronic acid 0.10 mol / Value of Hk/4πMs at the start of plating of the thus obtained magnetic disk and bath life (Hk/4πMs is 0.5 or less) Table 1 shows the number of plated sheets.

[Table] Compared to the comparative example, in this example, the medium characteristics and bath life were significantly improved, and the recording density characteristics of the obtained magnetic disk were also good and uniform. (Example 3) A magnetic disk was produced in the same manner as in the comparative example, but the following plating bath was used in this example. Plating bath (4) Cobalt sulfate 0.07mol / Nickel sulfate 0.12mol / Manganese sulfate 0.04mol / Ammonium perrhenate 0.005mol / Sodium hypophosphite 0.25mol / Ammonium sulfate 0.5mol / Sodium malonate 0.3mol / Sodium tartrate
0.1, 0.2, 0.3, 0.4, 0.5, 0.6 mol/ tartronic acid 0.04 mol/ Table 2 shows the value of Hk/4πMs at the start of plating and the bath life of the magnetic disk thus obtained.

[Table] Compared to the comparative example, in this example, the medium characteristics and bath life were significantly improved, and the recording density characteristics of the obtained magnetic disk were also good and uniform. (Example 4) A magnetic disk was produced in the same manner as in the comparative example, but the following plating bath was used in this example. Plating bath (5) Cobalt sulfate 0.07mol / Nickel sulfate 0.09mol / Manganese sulfate 0.02mol / Ammonium perrhenate 0.004mol / Sodium hypophosphite 0.20mol / Ammonium sulfate 0.5mol / Sodium malonate 0.3mol / Sodium tartrate 0.2mol / Tartronic acid 0, 0.01, 0.02, 0.03, 0.05, 0.07, 0.09,
0.15 mol/ Table 3 shows the value of Hk/4πMs at the start of plating and the bath life of the magnetic disk thus obtained.

[Table] Compared to the comparative example, in this example, the medium characteristics and bath life were significantly improved, and the recording density characteristics of the obtained magnetic disk were also good and uniform.
The properties were significantly improved by adding tartronic acid, demonstrating the remarkable effect of tartronic acid. (Effects of the Invention) As shown above in the comparative examples and examples, according to the present invention, at least cobalt ions, nickel ions, manganese ions, and rhenium ions are added as metal ions in the plating bath for producing magnetic films. By simultaneously containing at least a malonic acid group, a tartaric acid group, and a succinic acid group as a complexing agent for the metal ions in an aqueous solution containing at least a reducing agent for these metal ions, a PH buffer, and a PH regulator as agents, it is possible to use a perpendicular recording medium. A large number of magnetic recording bodies having uniformly excellent properties can be stably obtained. In the examples, only cobalt ions, nickel ions, manganese ions, and rhenium ions were used as metal ions, and reducing agents, PH buffers, and additives were used as additives.
Although a plating bath containing only a PH regulator, a malonic acid group, a tartaric acid group, and a tartronic acid group as a complexing agent has been described, brighteners, stimulants, smoothing agents, etc. agent, stress reliever,
It is also possible to add metal ions, additives, and complexing agents other than those mentioned above as pinhole inhibitors and the like.

[Brief explanation of the drawing]

Figure 1 shows Hk/ by the number of plated disks when magnetic disks were manufactured using the plating bath of the comparative example.
FIG. 2 is a diagram showing changes in 4πMs, and FIG. 2 is a similar diagram when the plating bath of Example 1 is used.

[Claims]

1. When a plurality of bundled steel pipes are sequentially immersed in a plurality of treatment tanks to perform the desired surface treatment, (a) the plurality of treatment tanks are placed together and close together, and the bundled steel pipes are placed between these treatment tanks. (b) The bundled steel pipes are immersed for a predetermined time in each tank position, then lifted and tilted to drain the liquid; (c) The steel pipes are moved, vertically moved and A method for surface treatment of steel pipes, characterized in that the tilting is performed by automatically operating a plurality of L-shaped steel pipe holding hooks that can be rotated and raised and lowered, and at least one of the hooks has a slip-preventing foot. .