KR900006304B1 - Magnetic recording carrier - Google Patents

Abstract

A magnetic recording medium comprises magnetic powders, 10-30 wt.% of the mixt. of a methyldiisocyanate-type polyurethane resin of tensile strength 500-800 kg/cm2 and a hexamethyldiisocyanatetype polyurethane resin of tensile strength 100-400 kg/cm2, 10-20 wt.% of a penoxy resin, and 1-10 wt.% of a plasticizer. The plasticizer is pref. di-2- ethylhexylazelate or tributoxyethylphosphate. The medium has a good durability and dispersibility.

Description

Magnetic recording media

The present invention relates to a magnetic recording medium.

In particular, the present invention relates to a magnetic recording medium having improved dispersibility of magnetic powder, durability of magnetic layer, flexibility and wear resistance in various magnetic recording media such as audio, computer, and video tape and magnetic disk.

Recently, a magnetic recording medium made of ferromagnetic powder and a binder on a nonmagnetic support such as a polyester base film is required to have characteristics such as high density recording and high output, and to improve physical and mechanical strength of the magnetic coating film.

In order to realize such high density recording and high output in a magnetic recording medium, improvement in the filling degree of the magnetic powder is required, and in order to increase the filling degree, high dispersion of the magnetic powder is also required.

And in order to improve the physical and mechanical strength of the magnetic coating film, the selection of the resin of the binder is very important.

In order to improve the filling degree of such magnetic powder, high dispersion, and physical and mechanical strength of the magnetic coating film, studies on selecting binders are being conducted.

As a result, the dispersibility of the magnetic powder and A method for improving the properties of coating strength has been proposed.

Polyurethane resin of the binder has excellent adhesive property in the manufacturing of magnetic tape, but it is unstable to run due to the increase of the coefficient of friction due to adhesiveness, and dispersibility of magnetic component is inferior but harden the coating film to increase durability. .

For high density recording, the magnetic powder has a small size and a large specific surface area, whereas the phenoxy resin facilitates the dispersion of the magnetic powder having a large specific surface area.

In addition, when a small amount of the plasticizer component is added to these resins, the flexibility of the magnetic layer is increased, and driving stability tends to be significantly increased.

An object of the present invention is to improve the properties such as high density recording and high output by improving the dispersibility of magnetic powder, durability of magnetic layer, flexibility and wear resistance in magnetic recording media, and to improve physical and mechanical strength of magnetic coating film.

The object of the present invention is a methyl diisocyanate (MDI) -based polyurethane (PU) resin having a tensile strength of 500-800 Kg / Cm² and a hexamethyl diisocyanate (HMDI) -based poly having a tensile strength of 100-400 Kg / Cm². This can be achieved by adding the urethane resin with the phenoxy resin and adding the plasticizer component.

Polyurethane resins (PU) used in the present invention include Estane -5701, -5707, -5710 of BF Goodrich, MAU-5020, -5100, -9300, N-3113, -2301 of MPU, and Pandex of DIC. T-5102S, -5000 S, -6085, -5610 and the like. Phenoxy resins include PKHH and PKHJ from Union Carbide.

In the present invention, the methyl diisocyanate-based polyurethane resin and the hexamethyl diisocyanate-based polyurethane resin may be used alone or a mixture thereof may be used. The ratio of urethane is preferably 1: 3 to 3: 1, and the amount of urethane is preferably 10 to 30% by weight based on 100% by weight of magnetic powder.

The phenoxy resin is preferably 10 to 20% by weight based on 100% by weight of the magnetic powder, and the plasticizer component is preferably 1 to 10% by weight of the resin component.

Plasticizers used in the present invention include di-2-ethylhexyl azelate and tributoxyethyl phosphate.

Other additives include dispersants, antistatic agents and lubricants. Dispersants include lecithin, fatty acid metal salts and fatty acid nitrogen derivatives (e.g. Duomeen-T, -TDO), and lubricants include higher fatty acids and fatty acid esters (13-21 carbon atoms). ) Liquid paraffin and silicone oil.

Meanwhile, solvents used in the present invention include tetrahydrofuran, methyl ethyl curtain, methyl isobutyl ketone, dimethylformamide, toluene, cyglohexanone, and the like.

The present invention will be described in more detail with reference to the following Examples.

The composition is placed in a ball mill and dispersed for 48 hours, followed by filtration, application and drying.

Next, after a cathetering process and a curing process (at 50 ° C. and under 88% relative humidity), they are punched into a disk having a diameter of 5¹ / 4 inch.

The disc is burnishing (surface grinding) and then the jacket is floated to make a floppy disk.

The measurement results of the disk thus made are as follows.

The magnetic properties were measured by magnetization (Vibrating sample magnetometer), and the wear resistance was measured by using a commercially available Taber wear resistance measuring device, and the driving frequency was 80% of the original input signal. The number of runs until decrement is shown, and the scratch is measured by a commercial scratch tester, and the weight of the touch when the touch causes damage to the coating surface.

Comparing Comparative Examples # 1 and # 2, the addition of the nucleated methyl diisocyanate-based polyurethane shows excellent dispersibility (magnetic properties), but the durability (run count) is poor, and when the methyl diisocyanate-based resin is added, dispersibility It can be seen that the durability is excellent.

In addition, it can be seen that the dispersibility is improved when the phenoxy resin is added in Comparative Examples # 3 and # 4.

And if the plasticizer component is not added, it can be seen that the wear loss is large.

In the Example performed based on the said result, it turns out that it shows the outstanding durability (running frequency) and the outstanding dispersibility (magnetic property) compared with the comparative example.

Claims (3)

A magnetic recording medium comprising a magnetic powder and a binder, the magnetic recording medium comprising tensile strength alone or mixed with a resin powder, and a phenoxy resin and a plasticizer component added thereto. The amount of each of the methyl diisocyanate-based polyurethane resin and the nucleated methyl diisocyanate-based polyurethane resin or a mixture thereof is 10-30% by weight based on 100% by weight of the magnetic powder, and the phenoxy resin is 10-%. A magnetic recording medium having 20% by weight and a plasticizer of 1-10% by weight of the resin component. 3. The magnetic recording medium of claim 2, wherein the plasticizer component is selected from the group consisting of di-2 ethylhexyl azelate and tributoxyethyl phosphate.