JPS5836409B2 - magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium provided with antistatic properties.

Generally, a magnetic recording medium is a substrate made of a polymeric resin such as a polyester base coated with a magnetic paint, which is a mixture of a binder also made of a polymeric resin and magnetic powder.

However, the base itself and the binder are insulators, and
The magnetic powder used is also a metal oxide with relatively high electrical resistance, such as γFe203, so the electrical resistance of the finished magnetic recording medium is high, which causes static electricity to be charged, which is the cause of attracting dirt and dust. It became.

Various methods have been proposed in the past as countermeasures against this problem, but typical ones include adding a surfactant to the magnetic paint, or adding conductive particles or other conductive materials.

The present invention focuses on the manufacturing process of γFe203 and controls the process appropriately, thereby making the magnetic powder itself highly conductive by adjusting the amount of impurities SOJ- and CI- contained in γFe = Os. The aim is to achieve an antistatic effect by using this material.

Impurities SOJ- and CI- were γFe,0 by wet method.
It usually comes in during the manufacturing process in step 3, but in the later stages of manufacturing, it is mostly eliminated by washing with water.

The present invention actively utilizes these impurities to prevent static electricity.

The present inventors discovered that 7” pet Os is an impurity SO,−,C
1- is γFe, 03 is SO4 − + 5
If it contains 01- = 0.4wt% or more, the electrical resistance will be extremely low, and by mixing this magnetic powder (hereinafter referred to as mix) with other magnetic powders, antistatic measures can be taken, and two types of It has been discovered that the electrical resistance of the above magnetic powder mixture can also be made low.

The amounts of SOJ- and C1- in the mix are adjusted during the manufacturing process, and this may be done by any method.

As a result of such control, the present invention allows impurity SO4-
, Ol- is important, and the process itself is not a problem.

For example, the manufacturing process for γFe=Os includes the following cases.

In these steps, impurities SO4- and CI- are contained.

The water washing step in the above method conventionally removes impurities such as SO+-
, 01- was sufficiently carried out until it became less than 0.2wt.

The r-Pe20s used in the present invention is obtained by washing with water for a very short time, unlike conventional methods, and the washing process of the present invention requires only a very short time compared to the time required for the conventional water washing process. .

The present invention will be specifically described below with reference to Examples.

Note that impurities in γFe20s are expressed as a percentage with respect to γFe,03.

Example 1 γFe,03 parts by weight. xrFetOs(S”-=”2-t%)y} 1005
01=0.2wt% Acrylonitrile rubber 60 Vinyl chloride-vinyl acetate copolymer 40 Above x+y=1
Several types of compositions in which X and y were varied while maintaining 00 were kneaded together with a solvent in a ball mill to make a magnetic paint, which was coated on a polyester base to produce a magnetic recording medium.

The electrical resistance was measured and a curve indicated by the triangle mark in FIG. 1 was obtained.

Example 2 rpc, Q,, X Weight part mix rFe 20s (SO+---0.6wt%
) y” 00 acrylonitrile rubber
60 Vinyl chloride-vinyl acetate copolymer 40
A magnetic recording medium was produced from this mixture in the same manner as in Example 1.

The results are shown in FIG. 1 by the square curve.

Example 3 γF e . 0. Weight part SO4 1120. 6-) } 100 Mix γ"""(501-"0.4 wt% y Acrylonitrile rubber 60 Vinyl chloride-vinyl acetate copolymer 40 A magnetic recording medium was produced from this blend in the same manner as in Example 1.

The results are shown in FIG. 1 as a curved circle. As can be seen from Figure 1, the SO. -+501- amount is 0.4w
t% or more, the ratio of mixed powder to the total amount of magnetic powder is 5w
At t% or more, a reduction in electrical resistance of about one order of magnitude or more is achieved.

Thus, according to the present invention, the antistatic effect can be achieved using the mixed powder.

As can be seen from FIG. 1, there is almost no difference in the effect between using the entire mixed powder and using 80% of the mixed powder.

Therefore, it is clear that it is more advantageous to add 5 to 80 wt % of mixed powder to ordinary magnetic powder than to use the entire amount of mixed powder.

[Brief explanation of drawings]

FIG. 1 is a graph showing the electrical resistance values of magnetic recording media containing impurities SOJ and Ol- according to the present invention.

Claims (1)

[Claims] 1. In a magnetic recording medium prepared by coating a substrate with a magnetic paint obtained by kneading one or more types of magnetic powder into a resin binder, one type of magnetic powder is γFe203, and impurities 804 and 804 contained therein. CI- is (80,-+501
-)/γFe203> Contains 0-4wt%,
Moreover, the above kind of magnetic powder is at least 5% of the total amount of magnetic powder.
A magnetic recording medium characterized in that it contains wt%.