JPS6263675A - Method for plating polyethylene terephthalate film with ferromagnetic metal - Google Patents

Abstract

PURPOSE:To improve the adhesion and magnetic characteristics of a metal deposited on a film by plating by etching the film with an aqueous soln. of an alkali metallic hydroxide, sticking palladium colloid to the surface of the film by a prescribed method and carrying out plating. CONSTITUTION:A polyethylene terephthalate film is etched with an aqueous soln. of an alkali metallic hydroxide. The etched film is immersed in palladium hydrosol contg. a cationic surfactant 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 Application Field] The present invention relates to a method for plating a polyethylene terephthalate film with a ferromagnetic metal.
By applying palladium colloid having a certain high catalytic activity to the surface of the PET film (referred to as UT film) and then chemically plating a ferromagnetic metal in a magnetic field,
Adhesion and magnetic properties (
The present invention relates to a ferromagnetic metal plating method that makes it possible to form a ferromagnetic metal plating film with good reproducibility.

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-plated 'F1 films have been attracting attention as high-density magnetic recording media with excellent reproduction output and sensitivity. It is necessary for the metal plating film to have excellent adhesion and to have excellent magnetic properties by being magnetically anisotropic.

Since the PET film surface is generally inert, in order to form a ferromagnetic metal coating on the PUT film surface by chemical plating, the PUT film surface must be etched beforehand, and then a catalyst for the reduction reaction of metal ions must be applied. It is necessary to add palladium to the surface of the PIET film.

Conventionally, methods for adding palladium to the surface of PET films include, for example, Journal Oscier Apply F
Physics (Journal of Applied
36 (1965), page 948.

This method involves a sensitization treatment in which a PET film etched with chromic acid-sulfuric acid and sodium hydroxide is immersed in an acidic hydrochloric acid solution of chloride No. 111 and then washed with water. It consists of two steps: immersion in a hydrochloric acid solution and activation treatment to deposit palladium on the PET film surface.

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 is based on the group (
Anti-strong acid? #1.7gradiu1, -tin coroly ['7 volume;
When contacted at night, it provides 41% palladium which catalyzes the chemical plating. This strongly acidic palladium-tin colloid '8? (l is, for example, trunc.
l Finiishi Inc. (Transaction
of the Institute of Metal
Finishing) Volume 51 (1973) No. 63
As described on the page, it is used for activation treatment of ABS resin, etc., but P[]゛Fil is not used.

[Problem that the invention seeks to solve]

City HB Journal Saibu 7 Bright Physics
↓When using my father's method, two baths are required, one for stannous chloride and one for palladium chloride, and washing with water must be done after each treatment to prevent the two solutions from mixing. The process is very complicated. Moreover, since the catalytic activity for chemical plating is low, sufficient palladium cannot be applied to cause the reduction reaction of metal ions to occur unless the same treatment is repeated two or three times.

In the case of the method described in the above-mentioned U.S. Pat. It interferes with the reduction reaction during chemical plating and causes a weakening of the adhesion strength between the formed metal film and the substrate. Therefore, in order to remove impurities other than palladium, the substrate is brought into contact with a strongly acidic palladium-tin colloidal solution. After that, further steps such as immersing the substrate in an acid or alkaline solution (acceleration treatment) are required.

Moreover, this strongly acidic palladium-tin colloidal solution changes over time and begins to precipitate 3 to 4 months after its preparation, resulting in poor 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 to solve the problem]

The present inventor applied palladium, which has a certain high catalytic activity, to the surface of a PET film by a simple 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, the present invention etches the surface of the target PIET film with an aqueous solution of alkali metal hydroxide, and then etches the surface of the target PIET film with a palladium hydrosol (
Palladium colloid is applied to the surface of the PET film by immersion in a colloidal solution), and then
P obtained by chemically plating ferromagnetic metal in a magnetic field
This is a metal plating method for ET film.

[Effect]

First, the most important point in the present invention is that palladium hydrosol containing a cationic surfactant is used to apply palladium colloid that acts as a catalyst for chemical plating to the surface of a roughly treated PET film. and chemical plating of ferromagnetic metals in a magnetic field.

In the present invention, palladium hydrosol containing a cationic surfactant is extremely stable, so it can be stored for a long time and can be used as needed. Because it does not require the acceleration treatment that conventional methods require, palladium has a constant high catalytic activity by simply immersing it in a palladium hydrosol containing a cationic surfactant. A colloid can be added, and further,
By chemically plating a ferromagnetic metal in a magnetic field, it can be made magnetically anisotropic, resulting in a film with excellent magnetic properties and a ferromagnetic film that can be used as a high-density magnetic recording medium. be able to.

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

The etching treatment of the I”ET film in the present invention is as follows:
A PET film is placed in an aqueous alkali metal hydroxide solution at a temperature ranging from room temperature to the boiling point, preferably 50 to 90°C.
This is done by immersing the sample for 0 minutes or more.

Note that it is preferable that the PET film used be 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, sulfur hydroxide or potassium hydroxide aqueous solution is used, and the concentration thereof is 1 to 10 mol/
l is desirable.

The palladium hydrosol containing a cationic surfactant in the present invention is prepared by adding a palladium salt aqueous solution such as palladium chloride (5) to sodium borohydride, hydrazine, etc. in the presence of a cationic surfactant as a protective agent. It can be obtained by reduction treatment with a water-soluble reducing agent such as, or by adding and mixing a cationic surfactant into palladium hydrosol produced in the absence of a cationic surfactant ( For example, Japanese Patent Application Laid-Open No. 59-120249).

As the cationic surfactant, a quaternary ammonium salt type surfactant such as stearyltrimethylammonium chloride is suitable, and it can be added before or after the reduction treatment. A nonionic surfactant or a water-soluble polymer such as polyvinylpyrrolidone may be added as a protective agent.

The concentration of cationic surfactant is 0.002-0.1%
A range of 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/(!).

In the present invention, the PIET film is immersed in palladium hydrosol containing a cationic surfactant by immersing it at a temperature ranging from room temperature to 100°C for at least 1 minute, preferably at least 10 minutes, and then pulling it out and washing it with water. It can be carried out.

The chemical plating of ferromagnetic metal in the present invention is carried out by magnetic
72,000 to 72,000, in a solution containing a ferromagnetic metal, a ferromagnetic metal is precipitated by reduction of the metal ion in the palladium colloid part. At this time, by applying a magnetic field from the outside, 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 in the present invention can be made to have anisotropy 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 koe.

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 mid-half value of this curve, and calculate this value at the coercive force of the peak value of the curve. It was calculated by dividing the

The adhesion of the plating was examined one hour after the completion of plating by strongly pasting a Scotch Mending Cheebe (manufactured by Jujutsu 3M 0G) onto the plated object and peeling it off.

Example 1 PU washed with ethanol for 10 minutes, then washed with water and dried
T film (manufactured by Toshi ■, thickness 20.8 cm, 4.
0 cm x 1, 5 cm) was immersed in a 50 °C aqueous solution containing 6.0 mol/l of sodium hydroxide, and
After 0 minutes, the sample was pulled up and washed with water to carry out etching treatment.

Apart from this, palladium chloride [1050, crmol
2. in an aqueous solution containing 250 μmol of sodium chloride.
The solution was dissolved in 5 ml and then diluted with pure water to 94 ml. While stirring this solution vigorously, 1 ml of an aqueous solution containing 10 mg of stearyltrimethylammonium chloride was added to the solution.
1, followed by 200 μmol of sodium borohydride.
When 5+ mL of an aqueous solution containing L was added dropwise, the color of the solution suddenly changed, and a transparent black-brown palladium hydrosol containing a cationic surfactant was obtained.

The etched PIET film was immersed in the obtained palladium hydrosol containing a cationic surfactant at room temperature for 60 minutes, and then washed with water.
The surface of the film was pale gray and had been coated with palladium colloid for chemical plating.

0.03 mol of cobalt sulfate (107 hydrate, 0.2
5 mol sodium hypophosphite, 0.5 mol
Sodium tartrate dihydrate and 0.50 mol of boric acid were dissolved in pure water to give IIl, and 3.3 mol of boric acid was dissolved in pure water.
Add l/II aqueous sodium hydroxide solution to adjust the pH to 9.
．． 0, and a cobalt chemical plating solution was prepared.

The PUT film to which the palladium catalyst colloid was applied was immersed in this cobalt chemical plating solution at a temperature of 63° C. in an applied magnetic field of 15 koe parallel to the PET film. After 7 minutes of immersion, the film was pulled out, washed with water, and dried to obtain a PIET film whose surface was uniformly coated with cobalt and had a metallic luster.

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 4900 G
auss, coercive force is 7550e, squareness ratio is 0.60, S
, F, D, was 0.40.

Comparative Example Go 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 PUT film is 4200 Gau
ss, coercive force is 7500e, squareness ratio is 0.50. S,
I', D, was 0.68.

Effect C] The method for plating a PET film with ferromagnetic metal according to the present invention is as described in 1. The palladium hydrosol used in the catalytic process does not contain impurities that interfere with the catalytic action of chemical plating, and has been used for a long time, so palladium has a certain high catalytic activity. Due to the possibility of applying colloids, PE
Because it has excellent adhesion to the T film surface and can exhibit magnetic anisotropy, it is possible to form a ferromagnetic metal plating film with excellent magnetic properties. .

Claims (1)

[Claims] (1) When forming a ferromagnetic metal film on the surface of a polyethylene terephthalate film by chemical plating, after etching the target polyethylene terephthalate film with an aqueous solution of alkali metal hydroxide, palladium containing a cationic surfactant is used. 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 by immersing it in a hydrosol, and then chemically plating a ferromagnetic metal in a magnetic field.