KR900002612B1 - The method of manufacturing of magnetic recording carrier - Google Patents

Abstract

A method for mafg. a magnetic recording carrier for video comprises (a) dispersing magnetic substance into a soln. [polyurethane resin (joined hydroxy gp. of up to 3.0 on terminal) contg. 0.01-0.1 wt.% dispersant , (b) 10-30 wt.% dissolving epoxy resinin the soln. (a), (c) 15 wt.% re-dispersing bridger into the soln. (b), and (d) coating the soln. onto base film.

Description

Method of manufacturing magnetic recording media for video

The present invention relates to a method of manufacturing a magnetic recording medium for video, and more particularly, to manufacturing a magnetic recording medium for video using polyurethane resins and epoxy resins to improve magnetic recording characteristics and increase wear resistance and durability of a magnetic layer. It is about a method.

In general, magnetic recording tapes, particularly computer or video magnetic recording tapes, have to be excellent in durability and magnetic recording performance at the same time to withstand heavy friction with the head. Therefore, several binder systems have been proposed.

For example, a technique for manufacturing a magnetic recording medium using a vinyl binder and a polyurethane resin is conventionally described in Japanese Patent Application Nos. 43-4623, 44-18222, 53-11444, and 52-11209. However, although the magnetic recording tape manufactured by this method has sufficient wear resistance because it uses a semi-conducting polyurethane, the vinyl resin used as a binder may have an adhesive force with the magnetic layer under conditions of high temperature and high humidity, thereby increasing the friction coefficient. In addition, the adhesive strength of the vinyl resin itself is also lowered, so that the durability of the magnetic tape becomes worse. In addition, when the magnetic coating is prepared by mixing the binder system and the magnetic powder, it is difficult to disperse the magnetic powder. Must be added again, the adhesion between the magnetic powder and the resin is significantly reduced and the magnetic layer is unstable about heat And easy to deteriorate, the surface contamination, were disadvantages such as lowering of durability.

In order to make up for the shortcomings, Japanese Patent Office 60-3573 said that a magnetic recording medium was manufactured by adding an epoxy resin to a vinyl resin to increase wear resistance and durability. However, even in this case, the vinyl resin itself lacks elasticity and thus satisfies durability. There was a disadvantage that I did not get.

On the other hand, a technique for manufacturing a magnetic recording medium using nitrocellulose as a dispersant and using a vinyl resin and a linear saturated polyester resin together as a binder has been introduced in US Pat. It is not good to bring about the same result as mentioned above, and the nitrocellulose used as a dispersant is difficult to handle because it has explosiveness itself, and the Tg of the nitrocellulose is high so that it is applied to the base film and then dried. (Curing) occurred badly, and the vinyl resin was not good because of its low magnetic strength and lack of adhesion to the base film.

In addition, US Pat. No. 4,415,95 used nitrocellulose as a dispersant and urethane resin as a binder. In this case, the above drawbacks were also shown due to the intrinsic properties of nitrocellulose, and the mechanical strength of the urethane resin was improved. In order to make a separate material to be added again, the manufacturing process took a lot of time, and there was a lot of problems, such as the gelation phenomenon is reduced productivity.

The present invention uses a polyurethane resin as a dispersing agent and an epoxy resin as a binder to improve the conventional defects of the present invention to manufacture a magnetic recording tape for video with excellent magnetic recording performance and improved wear resistance and durability. Is there.

Hereinafter, the present invention will be described in detail.

The present invention is to prepare a magnetic recording medium for video by dispersing the magnetic component as a dispersant, applying to the base film and orientation-dried, the solution is added in a solution containing 0.01 to 0.1% by weight of the dispersant in a polyurethane resin having a hydroxyl group of at least 3.0 First disperse the components and mix and dissolve the epoxy resin in a weight ratio of 90: 10 to 70: 30 with respect to the polyurethane resin, so that the binder solution is used in the range of 30 to 50% by weight based on the magnetic component. The crosslinking agent is added to 15% by weight or less with respect to the binder solution, redispersed, applied to the base film and orientation dried to produce a magnetic recording medium for video.

Hereinafter, the present invention will be described in more detail.

In the present invention, in applying a magnetic paint to a base film for producing a magnetic recording tape, at least one of, for example, mystic acid, stearic acid, or lecithin acid, which is a general dispersant, is used to disperse the magnetic component in a stable state. Selected and used, urethane resin is added and dissolved therein, diisocyanate is added to disperse the magnetic component, the paint is applied, then oriented and dried to prepare a magnetic recording tape for video.

On the other hand, the polyurethane resin used here is excellent in adhesive strength and dispersibility, but the strength is slightly lowered, so that the magnetic layer may be damaged when used in the magnetic recording tape, and driving may not be performed smoothly. Epoxy resin is added and used.

For example, when the driving is not smooth as described above, the wound state is not flat when the reel is wound. However, when the tape is stored in the uneven state, the recording state of the signal is deformed, which may cause a false signal.

Therefore, in the present invention, in order for the role of the urethane resin to be sufficiently performed, the end group of the urethane resin had a hydroxyl group, that is, the combined hydroxyl group was 3.0 or more. (For example, T _U -272, T ₁ -1331, manufactured by Nippon Sanyo Co., Ltd.), the dispersing force is significantly decreased when the hydroxy group is 3.0 or less. Compared with the dispersing force is much better, the dispersing force of the polyurethane is more significantly increased by adding the above dispersant.

At this time, addition of a dispersing agent should just be 0.01 to 0.1 weight% with respect to the polyurethane resin. If the content is less than 0.01% by weight, the required properties are somewhat insufficient. On the contrary, if the content is more than 0.1% by weight, the adhesive force is reduced as described above, and the surface is not contaminated.

As the epoxy resin used in the present invention, for example, Epikote-1009 (trade name) manufactured by Shell Chemical is most suitable.

The epoxy resin of the present invention is used in combination with the above-described urethane resin, wherein the mixing ratio of the urethane and epoxy is preferably 90:10 to 70:30 by weight. However, when the urethane is added at 90% by weight or more, the wear resistance and durability are slightly lowered. When the epoxy is added at 30% by weight or more, the magnetic layer becomes too hard to obtain the required physical properties.

More preferably, it is still more preferable if it is 90: 10-10: 80: 20 by weight ratio. In addition, the diisocyanate added as the crosslinking agent should be added to the solution dissolved in 50% of the solid content of 15% by weight or less based on the total binder, if added to more than 15% by weight, the change over time due to the diisocyanate, the electron conversion characteristics Will fall.

On the other hand, because of the hydroxyl group contained in the urethane resin during the dispersion of the magnetic component is strongly attached to the magnetic body and shows a better interaction due to the small amount of the dispersant added to it, put it in the magnetic component and redispersed by adding a dispersant thereto. Applying the magnetic coating to the base film, the orientation treatment by a magnetic field of 1500 Oe and drying to produce a magnetic recording tape having a square ratio of 0.82 level, excellent durability and wear resistance. At this time, 30 to 50% of the total weight of the magnetic powder of the binder used may be sufficient.

If the total amount of the binder exceeds 50% by weight of the magnetic component, the magnetic recording density becomes low, and when the amount of the binder is less than 30%, the performance of the binder in the magnetic layer is not sufficiently exhibited.

In the following examples, the present invention will be described in detail, but the numerical evaluation method of the following examples is not limited to the examples of the present invention.

[Each type ratio]

Measured in the direction in which magnetic components were oriented using a Japanese Toei Kogyo Co., Ltd., analgesic sample-type magnetic flux stopper.

[Steel Duration]

The magnetic tape is used as a video tape, and the image is first recorded on the tape, and a still image is reproduced during reproduction. At this time, the time from the stop time until the image is distorted is measured. The longer the time, the better the durability.

Durability Measurement

Using a wear-resistant measuring instrument made by Stain Bugs, measured at a wear rate of 13 m / s and a weight of 50 g at a tip height of 2.6 MILS.

[Shape wound on reel]

It shows good or bad shape when winding magnetic tape on reel at high speed.

[Hydroxy Evaluated]

Acetic anhydride or phthalic anhydride is dissolved in a pyridine solvent and then determined by acetylation or phthalation method. When the magnetic powder is dispersed, it is strongly attached to the magnetic layer due to the polar group such as the hydroxyl group of the urethane resin, and shows a better interaction due to the small amount of dispersant, thereby preventing reaggregation to the magnetic powder.

Therefore, after dissolving urethane resin in magnetic ingredients, dispersing agent is added to it and dispersing it, then dispersing epoxy resin and crosslinking agent in order to improve durability and wear resistance, redispers and apply magnetic paint to base film. After the orientation treatment at 1500 erstead magnetic field and dried, a magnetic recording tape having excellent durability and wear resistance is produced. This invention will be described in detail with reference to Examples.

Example 1

Methyl ethyl ketone: toluene: cyclohexanone = 1: 1: 1 Dissolve 90 g of urethane in 400 g of solution, add 300 g of magnetic powder, add 0.09 g of myristic acid as a dispersant, and disperse in a bowl mill for 30 hours. Next, 10 g of epoxy resin was dissolved in 200 g of methyl ethyl ketone: toluene = 1: 1 solution, added, 10 g of diisocyanate (50% solids solution) was added, and then dispersed in a sand grinder for 100 minutes.

The magnetic coating thus obtained is applied onto a 15-micron-thick polyethylene terephthalate base film and passed through a solenoid magnetic field of 1500 Ersted to orient the magnetic component, followed by drying to obtain a total thickness of 20 mu. Subsequently, the surface of the magnetic layer was smoothed and cut to an appropriate width by pressing in a 70 degree calendar roll to make a magnetic recording tape for video.

Example 2

In Example 1, adding 80 g of urethane and adding 0.08 g of 20 g mystic acid to the epoxy resin was carried out in the same manner as in Example 1 to make a magnetic recording tape for video.

Comparative Example 1

All procedures other than adding 60 g of urethane and 40 g of vinyl resin (slec A, slec C) instead of epoxy were carried out in the same manner as in Example 1 to prepare a magnetic recording tape for video.

Comparative Example 2

All procedures other than adding 60 g of vinyl resin (slec A, slec C) and 40 g of epoxy resin instead of urethane were carried out in the same manner as in Example 1 to prepare a magnetic recording tape for video. 15% by weight relative to epoxy resin)

The results evaluated through the examples and the comparative examples are shown in Table 1 below.

As described above, the magnetic recording tape prepared according to the present invention, unlike conventional tape, uses a small amount of a dispersant and is dispersed in a polyurethane having a hydroxyl group of 3.0 or more, and then puts epoxy resin to increase durability, thereby improving magnetic recording performance. And wear resistance also has the effect of enhanced durability.

TABLE 1

Claims (3)

To prepare a magnetic recording medium for video by dispersing a magnetic component with a dispersant, applying it to a base film, and orientation drying, the magnetic component is first dispersed in a solution containing 0.01 to 0.1% by weight of a dispersant in a polyurethane resin, and A binder solution is prepared by dissolving an epoxy resin in a binder, and then a crosslinking agent is added and redispersed in an amount of 15 wt% or less with respect to the binder solution, and then applied to the base film. The method according to claim 1, wherein the polyurethane resin is connected to a hydroxyl group of 3.0 or more at its terminal group, and the mixing ratio with the epoxy resin is mixed in a weight ratio of 90:10 to 70:30. The method of claim 1, wherein the binder solution is used in the range of 30 to 50% by weight based on the magnetic component.