JPS6038726A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance of a ferromagnetic metallic thin film and the adhesive strength of the film to a lubricant or a protective film by forming a coating contg. specified silanol groups and a chromium-oxygen compound on the magnetic film formed on a nonmagnetic support. CONSTITUTION:An aqueous soln. of a chromium-oxygen compound such as Cr2O3 or H2Cr2O4 is added to an aqueous soln. of a silane coupling agent represented by formula I [where X is a hydrolyzable group bonding to Si such as alkoxy or Cl, Y is a functional group such as cyclic epoxy or -SH, R is -(CH2)n-, and n>=1] or by formula II (where A is alkyl, and X is X in the formula I ) to prepare a soln. contg. 0.001-1.5mol/l Cr ions in 0.01-0.7mol ratio of Cr<3+>/Cr<6+>. The soln. is coated on a magnetic metallic thin film 2 formed on a nonmagnetic support 1, and it is dried by heating to form a tough coating 3 contg. silanol groups reacted with the chromium-oxygen compound. A lubricating film 4 or a protective film 5 with corrosion and wear resistances may be formed on the coating 3. The coating 3 improves the adhesive strength of the films 4, 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium in which a metal ferromagnetic thin film is formed on a nonmagnetic support by plating, vapor deposition sputtering, ion blating, or the like.

In recent years, in order to increase the residual 1M flux density and achieve high output during recording and reproduction, metals such as iron, cobalt, nickel, or alloys containing these materials have been replaced by plating, vacuum coating, etc. Magnetic disks and magnetic tapes have been put into practical use that are directly attached to a non-magnetic support by means such as vapor deposition, sputtering, ion blasting, etc. to form a ferromagnetic layer. These magnetic recording media are made of conventional ferromagnetic powder mainly composed of iron alloys.
Unlike ordinary magnetic recording media bonded with J binder, JRI tends to occur in high humidity or corrosive gas.

For this reason, anti-corrosion treatments such as oxidation by glow discharge on the entire surface of the medium, extremely thin resin coating, or glass coating are applied to improve its stability, but this is sufficient for practical use. We get the state of adding 451 to , which is 1[i. In particular, the high temperature, high humidity and calm weather during the rainy season are extremely bad conditions from the viewpoint of metal corrosion, and in fact, corrosion defects in various metal parts tend to occur more frequently during this period. In addition, the presence of corrosive gases contained in volcanic gases and exhaust gases from factories and automobiles is an extremely adverse condition for the erosion of metals not only during the rainy season but throughout the year.

As is well known, iron is eclipsed by Ii;j even in a normal environment, while nickel and cobalt are eclipsed by 11% compared to iron.
Although it has excellent eating habits, it easily turns into oxidized food under the above-mentioned environment. In particular, what is a metal plate?4, metal thin films made by plating, vacuum deposition, sputtering, ion blating, etc. are generally gold! Strong activity against A plate <+tV; tends to be easily eaten.

Magnetically recorded disks and tapes, whether analog or digital, need to be able to be stored for long periods of time without corrosion or deterioration to ensure signal quality.

A magnetic recording medium in which gold such as iron, cobalt, or nickel is coated with 'A or an alloy containing these as its main components by the method described above will undergo H4 corrosion in a relatively short period of time if left in various atmospheres. There are cases. For example, 60℃, 90~
In an atmosphere of 95% relative humidity, 114 corrosion may occur in a few weeks, and during the rainy season, white or dark brown spot-like corrosion products may be observed even if left indoors for several months. In order to prevent such deterioration due to corrosion, the surface layer of the 1D film of gold, metal, or alloy is subjected to pretreatment or protective film coating as described above, but even so, the corrosion resistance during the Nagawa period is not fully maintained. It is very difficult to guarantee this.

To solve this problem, a chromium chemical conversion coating 1f is applied to the surface of the metal or alloy thin film using a chemical method! It has been proposed to form an i'c shadow, in which the metal or alloy comprising iron, cobalt.

Gold such as nickel becomes ions and is eluted into the chromium chloride chemical conversion treatment solution, and at the same time hydrogen ions and chromium ions in the treatment solution are consumed. As a result, the free acid concentration of adult cows gradually decreases depending on the amount of processed material, until it reaches an appropriate level and no longer forms a romate film, and the treatment solution must be disposed of as waste and replaced with a new treatment solution. Must be.

The chromate treatment liquid that is disposed of as waste liquid contains a large amount of hexavalent and trivalent chromium ions, which are publicly regulated substances, so a pollution-free method is required to remove the chromium ions with a simple method. However, this g6 i'li process is not only very troublesome but also requires a large amount of processing cost.
-ru. In addition, after chromate treatment of the object to be treated, post-rinsing is required to remove excess treatment liquid remaining on the surface of the object, and treatment of the waste liquid discharged from this process is also an even more important problem. It's coming.

On the other hand, (magnetic recording media) come into sliding contact with magnetic heads and various types of diplides during their use.

For this reason, 41 properties of the medium, i.e. metals 1A
8) It is necessary to minimize the gap between the membrane surface and the sliding member as much as possible. In order to solve this problem, a liquid or homogeneous lubricant is applied to the surface of the thin film, and if necessary, an inorganic or organic wear-resistant lubricant such as silicon dioxide, acrylic resin, or vinyl resin is applied. A protective film is coated to protect the metal thin film from corrosion. The compatibility between the JIQ surface and the lubricant or protective film depends on the adsorption activity of the metal thin film surface, the bonding strength between the thin film and the lubricant or protective film, and It is influenced by many factors such as lubricants or the surface tension of the material itself, and is not necessarily formed uniformly over the entire surface of the pottery. The thickness of the adhesive, adhesive, and expansion layer tends to be uneven, which can cause bits and pinholes to occur.

In order to solve these problems, it has been proposed to previously perform chromate treatment or silane coupling treatment on the surface of the gold layer. However, chromate treatment has the above-mentioned problem with wastewater treatment, and silane coupling treatment has the problem that it does not have a strong anticorrosion effect on metal thin films. Until now, there has been no effective means for achieving both improvements in a non-polluting manner.

The present invention has been made in view of the above-mentioned points, and uses a non-polluting method that does not involve the generation of separate processing liquids to significantly improve the corrosion resistance of metal ferromagnetic thin films. It is intended to simultaneously improve the wettability and conformability of the agent or protective film, and provide a magnetic recording medium that is extremely practical and highly productive.

In order to achieve this object, the present invention provides a recording medium in which a metal ferromagnetic thin film is formed on a non-magnetic support.
Above the metal-clad 411 gland, there are silanol groups induced by hydrolysis from the silane coupling agent and chromium 1
A special feature is that a coating film containing a rope-laying compound is provided.

In the structure of the magnetic recording medium according to the present invention, the coating film 3 has (a) a metal toughness as shown in FIG.
←) It is placed between the metal ferromagnetic thin film 2 and the anti-corrosion and wear-resistant eye-retaining film 50 as shown in FIG. It may be placed above the metal ferromagnetic thin film 2 through the anti-corrosion and wear-resistant retention film 5 as shown in FIG. can be determined. Note that 1 in the figure is a nonmagnetic support. According to 1, which shows the more preferable suitability of the above configuration,
For tape-shaped media, (() is preferable, and for disk-shaped or drum-shaped media, (o) or (c) is preferable.

The 4th and 14th formations on the back → are anti-corrosion] Preventing the occurrence of spot corrosion in the thin film 2 of all 1511 strength 4 types caused by the presence of defects such as pinholes in the abrasive protective film 5. It is also effective in improving the wettability and conformability of the f1'A lubricant applied to the surface of the anti-corrosion h≧abrasion resistance. If necessary, a coating film 3 of 1 dimension may be formed on the surface of the protection B 25 in order to improve the wettability of the protection 11g 5 to the lubricant and the ability to rub it in when forming the roller 11.''.

A method for producing a direct recording medium according to the present invention is to apply a silane coupling agent and at least one of chromium M ions and pyrochrome 1-like ions to the surface of a metal ferromagnetic τη film formed on a non-magnetic support. A water-soluble treatment solution containing the above is uniformly applied by dipping, spraying, roll coating, etc., and water in the treatment solution is added to ζ゛; (
This process includes a step of evaporating and diffusing the metal ferromagnetic thin film by drying or the like to form a coating film on the surface of the metal ferromagnetic thin film.

In the present invention, the silanol group and chromic acid induced from the silane coupling agent in the coating Ili in the present invention are not clear; however, it is not clear in what form the compound proboscis exists, but it may be in the form of an ion or a molecule. shaped chrome L
It is considered that the W compound and the silanol group undergo a chemical crosslinking reaction.

In the method for manufacturing a magnetic recording medium of the present invention, the coating ff5'4 forming step will be explained in more detail.

The silane coupling agent used in the present invention has the general formula Y
its i X, or ASiX, and at least one type is selected from these. In the general formula, X represents a hydrolyzable group bonded to a silicon atom, and an alkoxy group -0CnH2n+1
(n≧1), acetoxy group -000CI (,.

Examples include halogen groups -Cz, -Brl, etc. Considering the hydrolyzable products, the use of the first two is preferred.

Further, Y represents an organic functional group, and is a vinyl group CH.

, =CH-, acryloxy group CH, COO-, cyclic epoxy group O-rei, mercapto group H8-, amino group 1-1.
N −, diamino group 1-1t N (C11t )n
NH (n≧1).

Examples include methacryloxy groups C11, CC11, COO-, glycide 1, and C. Also, A is the general formula "1 (
2r++1 (+1≧1) is an alkyl)V group, and R1 is an olefin bonding chain represented by the general formula -(C■'t)n (n≧1).

The chromium ion and pyrochromate ion sources used in the present invention are chromic anhydride CrOs g chromic acid Hv
Cry, , pyrro2C1 (g) is selected from at least one of R2Cr, Q, and ammonium salts thereof.

In the water-soluble treatment liquid prepared in the present invention, at least IMffljj4 of the silane coupling agent and the chromium enemy ion are selected, and adjusted in the following manner.

That is, first, a predetermined amount of the chromate ion 0t was weighed.
One volume of purified water from which impurities have been removed, such as ion-exchanged water or distilled water, is added to the original water, and then the silane coupling agent, which has been weighed to a certain Fi, is added to the solution H1-vc. At this time, some of the chromate ions (Cr) are reduced by the silane coupling agent, and this mechanism is generally thought to be as follows.

That is, the silane coupling agent is chromium ion (C
r) When added to an aqueous solution containing grapes, these groups or atoms undergo hydrolysis to form silanol and HX as shown in the following formula.
X metamorphosis occurs.

Y R81X3+ 3 M, 0→YR8i (011,
) + 3 HX For example, when X is a methoxy group or an ethoxy group, 1-I

The preferred treatment liquid composition of the treatment liquid used in the present invention is mo+ chromium dispersion ion per 1 treatment liquid, io, 001 to 1.5/
The molar ratio of trivalent chromium to hexavalent chromium (Cr
/Cr) was adjusted to contain 0.01 to 0.7. The reason why the composition of the processing liquid is limited in this way is as follows. Anhydrous chromium enemy's age is 01001
If it is less than 1.h, the treatment time will be long, and if the treatment is performed for a short time of less than 10 seconds, a film with excellent corrosion resistance will not be formed.1.
After 5 htlm, no improvement in corrosion resistance is observed, considering the addition linearity, compared to when it is less than 5 htlm.

Also, the molar ratio of 3 i1+[i chromium and hexavalent chromium is 0.
If it is less than 01, the effect of improving n61 eating habits is low, and 0.7>4
3, the content of trivalent chromium is very high (on the other hand, 3
Despite the high ROM concentration, the 1iuj eating quality improvement effect is not sufficient.

However, the above-mentioned limit was intentionally set from the viewpoint of production efficiency and addition efficiency, and these 1111 limitations are not strict.

The prepared treatment liquid is applied to the metal ferromagnetic material formed on the non-social support body by the immersion method based on a process according to the 119 composition of the magnetic recording medium. It is applied uniformly by means such as , spraying, coating, etc.

The drying may be carried out to the extent that the water content evaporates, and preferably the surface area reduction is 60 to 100°C, and the coating film appears as a coating film just before the water content evaporates from the treatment liquid.

The first feature of the magnetic recording medium and its manufacturing method according to the present invention is the stability of the processing liquid. Generally, the chromate treatment solution containing trivalent chromium is P H
If it exceeds 3, there is a tendency for precipitation or gelation to occur. However, when silane coupling AIJ is added to the chromate treatment solution, there is no problem with stability and concentration even when the pH is around 5.

Next, as a second feature, the corrosion resistance of the metal-reinforced thin film is extremely excellent, and the metal 5! of the formed coating film! I [It has excellent adhesion to magnetic thin lubrication and anti-corrosion thickness/protection, and has excellent wettability to lubricating films.
The compatibility is also extremely good.

This is because the silanol groups generated by hydrolysis, which is the original closure of the silane coupling agent, are caused by metal or
In addition to being adsorbed on inorganic films such as silicon dioxide, the form of the compound is not necessarily clear, but for example, Cry,
It is thought that a chemical reaction such as a crosslinking reaction occurs with a chromium gel compound represented by , Cr (OH), etc., which becomes strong and forms a romate skin. Since the silane coupling agent has 1i functional groups such as alkyl groups, ? 'HilJ lubricants and organic anti-corrosion and wear-resistance adhesives are closely bonded to membranes, etc.? It also has excellent TZ properties.

Furthermore, the third 4!1. The main point is that the coating process itself is a completely closed system, and unlike conventional chromate treatment, it is not necessary to dispose of waste from the aging treatment solution and waste from post-treatment cleaning at night; However, the usage efficiency of Process M is also close to 100%.

In the magnetic recording medium according to the present invention, the pre-heating layer and the anti-corrosion and wear-resistant insulating film may be any of those commonly used for magnetic recording media (not limited to !1). .

As lubricants, for example, polyfluorocarbon threads, polysiloxane threads, polyether threads, and overnight and solid polyesters can be used, and methods for applying them include dipping, spin coating, and spraying. law,
A roll coater method etc. can be used. In particular, when an extremely thin film is required, 7i'+"4
Wei v! , may be completely formed.

Corrosion and wear resistance: 91+! , p is 0.1μ
Any material may be used as long as it can be uniformly formed into a thin film of less than m, and inorganic materials such as Sin, glass family, At, and O3 films are generally formed by spin coding or sputtering. In addition, as organic materials, thin films such as Aku I)) Shigara 1 + It's Vinyl Qj JiIi, etc.
It can be formed by a spin code method or a sputtering method.

This invention is effective not only for improving the corrosion resistance of conventional magnetic recording media, but also for magneto-optical recording media made of alloy thin films of transition metals such as cobalt and iron and rare earth metals such as cadmium and terbium.

Next, the present invention will be explained with reference to examples. In this example, a Co-Ni-P alloy plate obtained by a chemical plating method, which is considered to be the most important method for ensuring corrosion resistance in terms of using water sound when making a metal ferromagnetic thin model, is used. Two membranes were used. The non-French support used was a JIS standard 5086 aluminum alloy plate coated with an amorphous N1-P chemical plating film.

Regarding corrosion resistance, which is one of the performance evaluations of Coating 11Q, the salt water resistance test was conducted to evaluate the coating 11R's tightness.
First, I performed an eye test. Salt water resistance 11J□1Q;
5 test conditions were based on JIS Z2371, and the corrosion state of the surface of the plating film after 96 hours of testing was observed, and the standard of passing was 71 k k %. Painting “f”
For the Jf 7ff property test, use a paint tray of Aku J17+Z series and prepare a painted test piece that is dried at 200°C for about 2 minutes.

I used a cutter to cut from the surface of this test piece so as to reach the Co-Ni-P-plated thin J-replacement substrate, cut it into a 1m+ square eyelet shape, and pasted Cero-N tape on it.
I quickly tore it off and inspected the extent of the abnormality on the painted surface. The criteria for passing was those with no peeling of the paint film.

Example l Anhydrous chromium E age 0.105, 7t Aqueous solution with 7 run coupling agent [vinyltriethoxysilane C1-1, =
C1(Si(0C14□C1-1s)s:] is 0
．． 103g was added and adjusted to = 0.5, and this treatment i
Co-Ni-P plating was applied to the surface of J) 3 by a spray method, and then dried at 60° C. to remove moisture from the treated cattle. As a result, a coating containing chromium with a skin group content of 20TH was formed on the surface of the plating thin film. When the performance of this coating film was evaluated, it was found that the I+ = corrosion incidence rate in the durable water test was zero compared to the case where the present invention was not implemented @ 305, and that there was no peeling of the coating film in the eye test. , compared to 50 taro or more if the present invention is not carried out, 10
It was less than 96.

Furthermore, the wettability to lubricants was also extremely good.

Example 2 Silane coupling agent [γ-mercaptopropylmethoxysilay H8C
l-1,CH2Cl-1,Si (0CI(,)s)
By adding 2.06g of , the final component composition has a Cr concentration of 0.1/l, Cr? a degree or 0.5
/1 The temperature ratio Cr /Cr or 0.2. This process 71 da is C.

-Ni-P plated thin film surface was coated using a roll coater method, then dried at 70°C, and water during the treatment process was evaporated for 4 hours.
I was against 1Ji. As a result, on the surfaces of the platings A, γj1 and 4, the amount of film was 60~/n? A coating film containing chromium was formed. When we evaluated the performance of this coating, we found that there was no incidence of Ii4 corrosion in the salt water spray test, and less than 10% of film peeling occurred in the square test.
It was Oka. Furthermore, the wettability to lubricants was also extremely good.

Example 3 Silane coupling of chromium ey 1-0 / to water 7*+ i
, CH, CH, Si (OCH,)3:]%' by adding 9.3 g, the final component composition changed to Cr
"Q degree is 0.4" 0L/l, 'Cr'+ concentration is 0.6/l.

The concentration ratio Cr/Cr of both is 0.67. This treatment liquid was dip-coated onto the surface of the Co-Ni-P plating thin film, made uniform by air squeezing, and then dried at 100°C to evaporate and evaporate water in the treatment liquid. As a result, a coating layer containing chrome cans with a coating amount of 70"t/lr was obtained on the surface of the thin plating film. When the performance of this coating film was evaluated, the snacking incidence (based on a salt water spray test) was First, the peeling rate of the f- film in the eye test was less than 10 taro and 4 i'j.The wettability against τ1ν1 slipping was also extremely good.

Example 4 By adding 5.1 g of a silane coupling agent (r-glycidoxyglobyltrimethoxysilane) to a pyrochrome flji20.5μ aqueous solution, the final component composition was Cr starvation 0.2/L, Cr Concentration 1J) 0.3
/l, the fatigue ratio of both Cr/Cr is 0.67.

This treatment liquid was dip-coated onto the surface of the Co-tNi-P plating thin film, made uniform by roll squeezing, and then dried at 70°C to evaporate and remove water in the treatment liquid. As a result, a coating containing chromium with a coating amount of 50''W/n?+15> was obtained on the surface of the plated thin film.

When we evaluated the performance of this removal, we found that ilj salt water";'(H
There was no rate of ll'5 eating in the test, and the coating film was determined by the mouth test! , '%, 1lJJ separation is 10% not j
l:'(It was. l!' Also, the wettability against the f slip was also extremely good.

Example 5 Ammonium chromate 0.2/lr chromium anhydride iM
Silane coupling 7i1J of O,5/ to an aqueous solution (
γ-glycidoxyglobiltrimethoxysilane) t4.
By adding 5g, the final component composition is er''-strength 0.2/L, (-r rivet resistance 0.5/L, ratio of both Cr/Sir 0.4) It becomes.This place (
11 was applied by dipping onto the Co-Ni-P-plated thin coated surface, made uniform by roll squeezing, and then dried at 80°C to allow moisture in the treated N solution and evaporation. . As a result, the surface of the plating film was coated with a layer of skin (iQ h19).
Chromium-containing coating films of / and A were coated. When we evaluated the performance of this lit↓, we found that there was no corrosion occurrence rate due to salt water resistance (I8I test), and coating peeling by the square test was less than 10% (high). It was also extremely good.

In addition, the above-mentioned coating rise is 8i0. When a glass coachine body was applied by a spray coating method and formed by a heating method at 200°C, it showed extremely good coating film peeling rate of less than several % by eye test. Obtained.

Example 6 Coating Δ5i (J2 Karasu Coating Gekkyu) on the surface of the Co-N i-P plating film by spray coating method.
ii After forming by the decomposition method at 200°C, a treatment liquid prepared in the same manner as in Example 2 was applied by spraying, and then dried at 70°C to remove the moisture in the treatment liquid. was evaporated and dissipated. As a result, the glass coating III,! On the surface, there is a membrane needle 40η/7? A chromium-containing coating was obtained. When evaluating the performance of this membrane, the corrosion incidence rate in the salt water spray test was found to be zero, compared to the corrosion incidence rate of 20 taro or more when the present invention was not implemented. Furthermore, the wettability to lubricants was also extremely good.

The present invention is based on the above-mentioned configuration, and includes a metal ferromagnetic thin film 1ij,! , by significantly improving the njt eating property of the surface and improving the coating adhesion, +'F
(j slip strength and anti-corrosion resistance) ≠ wettability and tightness with the protective film 1'7 strong: 'I=j can be removed. In addition, it is a completely closed system that does not involve disposal of the treatment liquid, allows for equalization of the treatment process, and since there is no change in the treatment composition, bath management is extremely easy.
Excellent productivity.

In the above examples, an amorphous non-magnetic N1-P film-treated aluminum alloy plate,
Metallic strong bee property τ1. Co -1'J i -P as γ film
Although chemical plating of 1 grade was used, other methods may also be used.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are cross-sectional views of a 1a recording medium according to the present invention. DESCRIPTION OF SYMBOLS 1...Nonmagnetic support, 2...Metal cylinder magnetic film, 3...Coating film, 4...Diseased synovial membrane, 5...・Corrosion protection Figure 1 Figure 3

Claims (1)

[Scope of Claims] (1) In a magnetic recording medium in which a metal ferromagnetic thin film is formed on a nonmagnetic support, a silanol group induced by hydrolysis from a silane coupling agent is provided above the metal ferromagnetic thin film. A magnetic recording medium characterized in that it is provided with a coating film containing a chromium oxygen compound. (2. A magnetic recording medium according to claim (1), characterized in that the coating film is provided between a metal ferromagnetic thin film and a 4^" slip trap. (3) 46. A magnetic recording medium according to claim (1), characterized in that the coating film is provided between a metal ferromagnetic thin film and a corrosion-resistant and wear-resistant protective film. (4) Patent Claim (1)M provides that an anti-corrosion and wear-resistant MJm is formed on the metal ferromagnetic thin film,
A magnetic recording medium characterized in that the coating film is formed on the aeration storage. (5) A magnetic recording medium according to claim α), wherein the silane coupling agent is a compound represented by the following general formula. General Formula % Formula % However, in the formula, Y is an organic functional group, and C) is an olefin bond chain represented by i, +n, or a hydrolyzable group bonded to a silicon atom. (6) A magnetic recording medium according to claim (1), wherein the silane coupling agent is a compound represented by the following general formula. -Liquid formula However, the person in the formula is an alkyl group or a hydrolysis cuffing group bonded to a silicon atom. (7) In claim (1), the pre-8 self-chromium compound is at least one glazed compound selected from the group of chromic anhydride, chromic acid, pyrochromic acid, and ammonium salts thereof. An e-ki recording medium characterized by certain things.