JPS6263676A - Method for plating polyethylene terephthalate film with ferromagnetic metal - Google Patents

Abstract

PURPOSE:To improve the adhesion of a metal deposited on a film by plating by etching the film by a prescribed method, treating it with an aqueous soln. of a cationic surfactant, sticking palladium colloid to the surface of the film and carrying out plating. CONSTITUTION:A polyethylene terephthalate film is etched with an aqueous soln. of an alkali metallic hydroxide and treated with an aqueous soln. of a cationic surfactant or hydrosol of a metallic hydroxide. The treated film is immersed in palladium hydrosol contg. one or more among an anionic surfactant, a nonionic surfactant, and a water soluble polymer to stick palladium colloid to the surface of the film. A ferromagnetic metallic film is then formed on the surface of the film by chemical plating in a magnetic field.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for plating a polyethylene terephthalate film with a ferromagnetic metal.
R? By applying palladium colloid having a certain high catalytic activity to the surface of the PET film, and then chemically plating a ferromagnetic metal in a magnetic field,
The present invention relates to a ferromagnetic metal plating method that makes it possible to reproducibly form a ferromagnetic metal plating film with excellent adhesion and magnetic properties on the surface of a film with simple operations.

The main use of the PET film on which the ferromagnetic metal coating according to the present invention is formed is as a high-density magnetic recording medium.

[Conventional technology]

Recently, ferromagnetic metal plating thin films have been attracting attention as high-density magnetic recording media with excellent playback output and sensitivity, but in order to obtain such ferromagnetic metal plating thin films, it is necessary to have a ferromagnetic metal plating film in close contact. It is necessary to have excellent magnetic properties by being magnetically anisotropic and having excellent properties.

The surface of the ET film is generally inert, so in order to form a ferromagnetic metal film on the PET film surface by chemical plating, the PET film surface must be etched in advance, and then etched to cause a reduction reaction of metal ions. It is necessary to apply palladium to the PET film surface as a catalyst.

Traditionally, PI! As a method for adding palladium to the surface of the T film, for example, there is the method of applying palladium to the surface of the T film.
d Physics) Volume 36 (1965) No. 948
There is a method described on page.

In this method, chromic acid is added to a solution of stannous chloride in hydrochloric acid.
P etched with sulfuric acid and sodium hydroxide
I! ? Two steps: sensitization treatment in which the film is immersed and then washed with water, and activation treatment in which the sensitized PET film is immersed in an acidic solution of palladium chloride in hydrochloric acid to deposit palladium on the surface of the PHT film. Consisting of

Furthermore, as a method for imparting palladium in one step, there is, for example, the method described in US Pat. No. 3,011,920.

The method described in U.S. Pat. No. 3,011,920 involves contacting a substrate with a strongly acidic palladium-tin colloidal solution to provide palladium to catalyze chemical plating. This strongly acidic palladium-tin colloidal solution can be used, for example, in
tion of the institute of
Metal Fir+jshtng) No. 511 (1
973), page 63, it is used for activation treatment of ABS resin, etc., but it is not used for PET film.

[Problem that the invention seeks to solve]

The method described in the aforementioned Journal of Apply F74 Difx requires two baths of stannous chloride and palladium chloride, and must be washed with water after each treatment to prevent mixing of the two baths. The process is extremely complicated. Furthermore, since the catalytic activity for chemical plating is low, it has the disadvantage that sufficient palladium cannot be applied to induce a reduction reaction of metal ions unless the same treatment is repeated two or three times.

In the method described in the above-mentioned US Pat. No. 3,011,920, in addition to palladium, which acts as a catalyst for chemical plating, a large amount of tin hydroxide etc. is also applied to the substrate, so these impurities can be used to prevent chemical plating. In addition, it becomes a cause of weakening the adhesion strength between the formed metal film and the substrate. Therefore, after bringing the substrate into contact with a strongly acidic palladium-tin colloidal solution to remove impurities other than palladium, it is necessary to further immerse the substrate in an acid or alkaline solution (acceleration treatment).

Moreover, this strongly acidic palladium-tin colloidal solution changes over time and begins to precipitate 3 to 4 months after its preparation, and has the drawback of lacking stability and reproducibility.

Furthermore, since the ferromagnetic metal plating films obtained by these known methods are magnetically isotropic, they are inferior in magnetic recording properties such as reproduction output and sensitivity when used as magnetic recording media.

As mentioned above, by applying palladium, which has a certain high catalytic activity, to the surface of the PET film by a simple operation, and then chemically plating a ferromagnetic metal with magnetic anisotropy, it is possible to improve adhesion and magnetic properties. There is a current need to establish a method for forming ferromagnetic metal plating films with excellent characteristics with good reproducibility.

Means for Solving Problem c] The present inventor applied palladium having a certain high catalytic activity to the surface of a PET film in an intermittent operation, and then
As a result of various studies on methods of chemically plating ferromagnetic metals with magnetic anisotropy, the present invention was arrived at.

That is, in the present invention, the surface of the target PET film is etched with an aqueous solution of an alkali metal hydroxide, then treated with an aqueous cationic surfactant solution or a metal oxide hydrosol (colloidal solution), and then anionically etched. Palladium colloid is applied to the surface of the PET film by immersing it in a palladium hydrosol containing one or more selected from ionic surfactants, nonionic surfactants, and water-soluble polymers. and then chemically plating a ferromagnetic metal in a magnetic field. This is a ferromagnetic metal plating method for T film.

[Effect]

First, the most important point in the present invention is that the PET film is etched with an aqueous solution of an alkali metal hydroxide and then treated with an aqueous cationic surfactant solution or a metal oxide hydrosol. When applying palladium that performs a catalytic action for plating, a palladium hydrosol containing one or more selected from anionic surfactants, nonionic surfactants, and water-soluble polymers is used. The second point is that ferromagnetic metal is chemically plated in a magnetic field.

In the present invention, palladium hydrosol containing one or more selected from anionic surfactants, nonionic surfactants, and water-soluble polymers is extremely stable. It can be stored for a long period of time and can be used at any time, and since it does not contain impurities that would interfere with the catalytic action, it does not require the accelerating treatment that conventional methods require. Palladium, which has a constant high catalytic activity, can be produced by simply etching a PET film with a hydroxide aqueous solution, treating it with a cationic surfactant aqueous solution or a metal oxide hydrosol, and then immersing it in the palladium hydrosol. Colloids can be added, and by chemically plating ferromagnetic metal in a magnetic field, it can be made magnetically anisotropic, resulting in excellent magnetic properties and high-density magnetic properties. A ferromagnetic film can be obtained as a recording medium.

Next, various conditions for implementing the method of the present invention will be described.

The etching treatment of PET film in the present invention is as follows:
The ET film is placed in an aqueous alkali metal hydroxide solution at a temperature ranging from room temperature to the boiling point, preferably from 50 to 90°C for 10 minutes.
This is done by immersing it for at least a minute.

In addition, the PI used! It is preferable that the T film is previously degreased with ethanol or the like, washed with water, and dried.

As the alkali metal hydroxide aqueous solution used in the etching process in the present invention, a sodium hydroxide or potassium hydroxide aqueous solution is suitable, and the 4 degree is preferably 1 to 10 mol/1.

The cationic surfactant aqueous solution in the present invention includes:
A quaternary ammonium salt type such as stearyltrimethylammonium chloride or dodecylpyridinium chloride dissolved in an aqueous solution at a concentration of 0.1 to 5% can be used.

The metal hydroxide hydrosol in the present invention is, for example, an iron hydroxide hydrosol obtained by rapidly hydrolyzing an iron chloride (2) aqueous solution in boiling pure water, or an iron hydroxide hydrosol produced by a gas phase method. A hydrated aluminum oxide hydrosol prepared by dispersing commercially available aluminum oxide in water can be used.

In the present invention, the etched PET film can be treated with a cationic surfactant or metal hydroxide hydrosol by immersing it at a temperature in the range of room temperature to 100° C. for 5 minutes or more.

The palladium hydrosol in the present invention is a palladium salt aqueous solution such as palladium chloride (1), and one or two kinds of protective agents selected from anionic surfactants, nonionic surfactants, and water-soluble polymers. It can be obtained by reduction treatment with a water-soluble reducing agent such as sodium borohydride or hydrazine in the presence of the above (for example, JP-A-59-120249).

Examples of anionic surfactants include sulfonic acid type surfactants such as sodium dodecylbenzenesulfonate, nonionic surfactants include polyethylene glycol-P-monononylphenyl ether, and water-soluble polymers include polyvinylpyrrolidone. When used, these surfactants and water-soluble polymers can be used alone or in combination of two or more.

The concentration of surfactant and water-soluble polymer is 0.002 to 0.
．． A range of 1% is preferred.

The palladium concentration in the palladium hydrosol used in the present invention is preferably in the range of 0.1 to 2 mg-atom/jl'.

The PUT film in the present invention can be immersed in palladium hydrosol at a temperature ranging from room temperature to 100° C. for 1 minute or more, preferably 10 minutes or more, and then pulled up and washed with water.

The chemical plating of ferromagnetic metal in the present invention is carried out in a magnetic field, that is, in a solution containing ferromagnetic metal ions and a reducing agent, the metal ions are reduced by the palladium colloid part, thereby depositing the ferromagnetic metal. However, at this time, by applying an external magnetic field in an aperture manner, the arrangement of the magnetic domains is adjusted to provide anisotropy, thereby improving the magnetic properties.

The object of the present invention can be achieved if the strength of the magnetic field is 1 koe or more, but it is preferably 3 kOe or more in consideration of the magnetic properties of the resulting ferromagnetic metal plating film.

The ferromagnetic metal plating film according to the present invention can be made to have a different J property in any direction by changing the direction of the magnetic field.

As the ferromagnetic metal for chemical plating in a magnetic field according to the present invention, one or more water-soluble salts such as nickel, cobalt, iron, and chromium can be used.

As the reducing agent for chemical plating in the present invention, sodium hypophosphite, formaldehyde, etc. can be used.

〔Example〕

Next, the present invention will be explained by examples.

The magnetism in the examples was measured in a magnetic field of 10 kos.

To measure S, F, and D, use the differential circuit of the magnetic measuring instrument to obtain a differential curve of coercive force, measure the half-width of this curve, and set this value at the coercive force at the peak value of the curve. It was calculated by dividing the

The adhesion of the plating was examined by firmly pasting Scotch mending tape (manufactured by Jujutsu 3M ■) on the plated object and peeling it off one hour after the completion of plating.

Example 1 After washing with ethanol for 10 minutes, washing with water and drying PET film for magnetic tape (manufactured by Toshi ■, thickness 20.8 μm)
,4cm
After 0 minutes, the sample was pulled up and washed with water to carry out etching treatment.

A hydrated aluminum oxide hydrosol was prepared by dispersing 0.2 g of aluminum oxide powder ("^1uminius+ Oxide C'" manufactured by Nippon 7Edsyl ■) in 100 ml of pure water at room temperature.In this hydrosol, the above-mentioned The PET film was immersed at a temperature of 80°C.30
After 2 minutes, the film was pulled out and thoroughly washed with water.

Separately, palladium chloride value) 50μsol, 250.1
2.5 ml of an aqueous solution containing sodium chloride of 711101
and then diluted to 94ml with pure water. While vigorously stirring this solution, 1 cup of an aqueous solution containing 10 mg of polyethylene glycol mono-P-nonylphenyl ether (degree of polymerization of the polyethylene glycol moiety: 10) was added to the solution, followed by 200 pm of sodium borohydride.
.

! When 5 ml of an aqueous solution containing .

The above-mentioned PET film treated with hydrated aluminum oxide hydrosol was immersed in this palladium hydrosol at a temperature of 80°C for 30 minutes, and then the film was pulled up and washed with water to form a PET film with palladium colloid added to the surface.
A film was obtained.

Then, 0.03 mol of cobalt sulfate heptahydrate, 0.25 mat of sodium hypophosphite, 0.50
mol of sodium tartrate dihydrate and 0.50 nol
of boric acid was dissolved in pure water to obtain 11, and 3.3 m
Add ol/12 aqueous sodium hydroxide solution to adjust pH to 9.
The PET film to which palladium colloid was applied was immersed in a cobalt chemical plating solution adjusted to zero in a magnetic field of 5 kOe parallel to the film at a temperature of 63°C.

After 7 minutes of immersion, the film was pulled up, washed with water, and dried to form a highly adhesive ferromagnetic metal cobalt film with a thickness of 0.55 μm on the PET film surface.

Even when the mending tape was strongly pressed against the surface of this PET film and peeled off, the cobalt film did not peel off.

In addition, the residual magnetic flux density of this PET film is 5740G
auss, coercive force is 7660e, squareness ratio is 0.64,
S, P, D.

was 0.28.

Example 2 A PET film coated with palladium colloid was plated with Co in the same manner as in Example 1 except that the magnetic field strength was 15 kOe.

The surface of the obtained PET film has a silvery white color.
Even when the mending tape was strongly pressed and removed, the ferromagnetic cobalt film did not peel off. In addition, the residual magnetic flux density of this PET film is 6000 Gauss, and the coercive force is 7.
900e, squareness ratio is 0.66, S, F, Il, 0.1
It was 9.

Comparative Example Co plating of PET film was performed in the same manner as in Example 1, except that no magnetic field was applied during chemical plating.

The residual magnetic flux density of this PET film is 4320 Gau
ss.

Coercive force is 8000e, squareness ratio is 0.52, S, F, D,
was 0.40. [Effect] As shown in the previous example, the method for ferromagnetic metal plating of a PUT film according to the present invention is such that the palladium hydrosol used in the present invention hinders the catalytic action of chemical plating. Since it does not contain any impurities and is stable over a long period of time, it is possible to provide palladium colloid with a certain high level of catalytic activity, and it has excellent adhesion to the PET film surface. Furthermore, since it can be magnetically anisotropic, it is possible to form a ferromagnetic metal plating film with excellent magnetic properties.

Claims (1)

[Claims] (1) When forming a ferromagnetic metal coating on the surface of a polyethylene terephthalate film by chemical plating, the target polyethylene terephthalate film is etched with an aqueous solution of an alkali metal hydroxide, and then a cationic surfactant aqueous solution or After treatment with metal hydroxide hydrosol, immersion in palladium hydrosol containing one or more selected from anionic surfactants, nonionic surfactants, and water-soluble polymers. A method for plating a polyethylene terephthalate film with a ferromagnetic metal, the method comprising applying palladium colloid to the surface of the polyethylene terephthalate film, and then chemically plating a ferromagnetic metal in a magnetic field.