JPH034265B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a surface coating forming apparatus used for manufacturing, for example, metal thin film magnetic tape. Here, metal thin film magnetic tape is formed by depositing, sputtering, plating, etc. a magnetic thin film of iron, cobalt, nickel alone or an alloy on a plastic film substrate made of polyethylene terephthalate, polyimide, polyamide acetate, cellophane, etc. This is what I did. Among these, the method of forming a magnetic thin film by vapor deposition is, for example, carried out several times while conveying a plastic substrate such as polyethylene terephthalate in a cylindrical can in a vacuum of ^{10 -4} to ^{10 -6} Torr. A magnetic metal such as cobalt or a nickel alloy containing cobalt as a main component is scattered in a trace amount of oxygen gas atmosphere in a crucible heated by an electron beam accelerated to 10KV, and magnetic metal is applied to the surface of the plastic substrate on the can. It forms a film. Metal thin film magnetic tape has excellent recording and reproducing characteristics, especially in the short range of recording wavelengths of several microns or less, and uses short wavelength recording.
VTR tape, microcassette tape,
Suitable as PCM recording tape. By the way, since the magnetic film is composed of a magnetic metal material, when used as a magnetic tape, unlike conventional coated tapes, there is a slight problem in running properties. For this reason, it is common practice to provide an organic layer with good slip properties on the magnetic film to improve running properties. However, when an organic layer is provided as described above, the gap loss between the magnetic film and the head is large in the short wavelength region, and therefore the organic layer on the magnetic film cannot be thick. Here, the gap loss is expressed by the following formula. Gap loss (dB) = 54.6d/λ (d = gap between tape and head, λ = recording wavelength) From the above formula, for example, the loss when recording wavelength λ = 1μ and gap d = 0.1μ becomes 5.46dB, and the output is about half of that without gap loss. In magnetic recording and reproducing devices that use recording wavelengths of 1 μ or less,
It is desirable that the organic layer on the magnetic film has a thickness of 200 Å or less. In this case, the loss is approximately 1 dB at a recording wavelength of 1 μ and 2 dB at a recording wavelength of 0.5 μ. As can be seen from the above, it is necessary to form a very thin organic layer on the magnetic film.
This is extremely difficult with conventional technology. Conventionally, for example, as a technique for uniformly applying organic substances, there is a technique of applying with a gravure roll, but in that case, even if the concentration of the plate roll and coating liquid is controlled, the coating thickness is 0.5μ or more, and the thickness is 0.02μ. At present, there is no technology suitable for application of this degree. The present invention has been made in view of the above points, and embodiments thereof will be described below with reference to the drawings. FIG. 1 shows the structure of a film forming apparatus according to the present invention. In the figure, 1 is a supply unit for the raw metal thin film tape 21 to be processed, and 2 is the raw metal thin film tape 21.
A pair of supply rollers transports the original tape 2.
It rotates while holding 1 and sends it out at a constant speed. 3 is a roller called a back-up roll that holds the original fabric 21 in the coating section. 4, 5, 6, 7 are
This is a guide roller for conveying the tape original fabric 21. 8 is a winding section of the processed original fabric.
Reference numerals 9 and 10 are heating drying ovens for completely scattering solvent components during surface treatment. Reference numeral 11 denotes an application unit for applying a coating liquid having components for adhesion, 12 a supply pump for the coating liquid, and 13
is the coating liquid tank. Reference numeral 14 denotes a diluting solvent application section for applying a solvent for diluting the coating liquid. 15 is a pump for supplying diluting solvent, and 16 is a tank for diluting solvent. 17 is an air knife for scattering unnecessary parts of the coating solution diluted with the diluent, and 18 is a compression pump for gas sent to the air knife. Air is normally used as the gas, but N may be used depending on the purpose. ₂ ,
Ar gas is used. Reference numeral 19 denotes a filter, and when manufacturing metal thin film tapes, a filter is used that removes dust of 0.1μ or more. 20 is a device for recovering the solvent and air blown off by the air knife, and is forcibly exhausted to the outside by a fan. FIG. 2 shows an enlarged view of the application area. In the figure, 22 indicates a coating liquid. 23 is a back-up roll that supports the original fabric 21, 24 is a coating nozzle, and 25 is a nozzle that sends out a coating liquid. 2
A liquid reservoir 6 is used to adjust the pressure so that the liquid comes out uniformly from the entire surface of the nozzle. 27 is a supply port for the coating liquid, 28 is a receiving part for collecting the coating liquid spilled to the rear of the coating nozzle, and 29 is a groove for collecting the coating liquid. As shown in FIG. 2, the application section includes application nozzle 2.
The coating liquid 22 is supplied from the tip of the nozzle 4, and the coating liquid 22 is accumulated in the gap between the original fabric 21 and the nozzle 24.
When the liquid 22 moves, the liquid 22 adheres to and is applied to the original fabric 21 due to surface tension. In an example of processing by this apparatus, the composition of the coating liquid applied by the coating section 11 in FIG. A solution containing 0.5 parts of stearic acid and 0.1 parts of silicone oil is used. When the liquid applied in the application part 11 passes in front of the nozzle of the application part 14, acetone is applied by the nozzle of the application part 14, so the components of acetyl cellulose and stearic acid in the liquid applied in the application part 11 are diluted. Ru. However, on the magnetic film of the tape 21,
A thin film has already been formed with the concentrated coating solution, and the diluted coating solution is no longer needed. During this process, when the diluted and unnecessary coating liquid is scattered by the air knife 17, a thin, high-quality coating is formed on the surface of the magnetic film. However, since the film still contains a small amount of solvent, the formation of the film is completed by completely removing the solvent in the drying ovens 9 and 10. Here, as an example of simply forming a thin film, it is possible to form a thin film by lowering the solids concentration in the coating solution from the beginning, but the quality of the film is is not guaranteed. Further, if unnecessary coating liquid remains, the film thickness increases, and the quality of the film, which is intended to improve runnability, deteriorates. Next, an example of film formation that can be expected to improve running performance and prevent rust will be explained. Application section 1 in Fig. 1
The coating liquid applied by nozzle 1 uses a metal salt of perfluoroalkylcarboxylic acid (C _o F _2o+1 COOH). The types of metal salts in this case are Co, Ni,
Metal salts such as Cr and Cu are selected, and water is used as the solvent. The concentration is chosen in the range 0.1% to 0.01% by weight. In this case, the liquid applied by the nozzle of the application section 14 is water. It is thought that on the magnetic film coated by the nozzle of the coating section 11, the metal part of the metal salt of perfluoroalkyl carboxylic acid and the surface of the magnetic film chemically react, forming a film close to a monomolecular film. It will be done. Immediately after forming such a film, if the unnecessary coating solution is diluted and washed with water, a desired film is formed on the magnetic film. Note that excess unnecessary coating liquid is scattered by an air knife 17 to prevent the film from becoming thicker. Film formation is completed by passing through the drying ovens 9 and 10 to completely remove moisture. Next, the test results for the metal thin film tape completed by forming a film made of acetylcellulose and stearic acid on the magnetic film as described above are shown in the table below.

[Table] In the table, the output at a recording wavelength of 1μ is measured using a metal thin film tape.
This is a comparison of the output values when reproducing data recorded at saturation at a recording wavelength of 1μ. As a standard for comparison, the output of a tape without a coating on the magnetic film was taken as OdB. With the above tape, when measuring,
Although the running performance was poor and the measurement conditions were poor, the maximum output value was used as the reference value. The coefficient of friction of a magnetic surface depends on the material.
Friction when a SUS round bar with a diameter of 10 mm and a buffed surface is used, and the magnetic surface of the tape is brought into contact with the bar by an angle of π/2 [radian] and moved at a speed of 50 mm/sec. This is the result of measuring force. Further, in the table, method A refers to a method using the apparatus according to the present invention, and method B refers to a method in which film formation was performed without using the diluting solvent application section 14 in the apparatus according to the present invention. Naturally, the one without coating shown in the table has the smallest gap between the magnetic surface and the head.
Therefore, the spacing loss is reduced, but due to poor running performance, the maximum output is obtained although there are large fluctuations, and the maximum output is therefore used as the reference output. The coefficient of friction of the material without coating is a large value of 0.4. On the other hand, when a film is formed by method A, fluctuations in output are reduced, and the maximum output can be obtained. This indicates that the coating was formed to a thickness that did not cause any problems with the gap between the magnetic surface and the head, and that the coefficient of friction was lowered and running performance was improved. In the case where the film was formed using method B, the deterioration of the output characteristics was noticeable, and was 6 dB worse than the initial value.
It was confirmed that this was due to the thick coating formed on the surface of the magnetic film. Although the film formed by method B does not have a particularly large coefficient of friction, it cannot be used as a magnetic tape due to the problems described above. In addition to the improved runnability, the products using metal salts of perfluoroalkyl carboxylic acids were also found to have improved rust prevention effects. This seems to be due to the added effect of the metal salts mentioned above. As described above, by using the apparatus according to the present invention, it is possible to easily form a coating having a very thin thickness and excellent quality. In the description of the above embodiments, the case where the apparatus according to the present invention is used to manufacture a metal thin film tape has been explained, but the apparatus according to the present invention can also be used in other fields, and its industrial value is great. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of a film forming apparatus according to the present invention, and FIG. 2 is a sectional view of the main parts of the apparatus. 1... Supply section, 3, 4, 5, 6, 7... Roller, 8... Winding section, 9, 10... Drying oven, 1
1, 14... Application part, 17... Air knife, 21
... Tape original, 22 ... Coating liquid, 25 ... Nozzle, 26 ... Liquid reservoir.

Claims (1)

[Claims] 1. A supply means for supplying the raw fabric on which a film is to be formed, an application unit for applying a coating liquid to the surface of the raw fabric supplied from the supplying means, and a coating unit for applying a coating liquid to the surface of the raw fabric supplied from the supplying means. a diluting section that adds a diluting solution to dilute the coating solution; an air knife generating means that scatters an unnecessary portion of the coating solution diluted with the diluting solution; and a source from which the unnecessary portion of the coating solution is scattered by the air knife generating means. A film forming device comprising means for heating and drying a cloth.