JPS6111923A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled magnetic recording medium having a small coefficient of kinetic friction and excellent traveling stability and durability by forming a magnetic layer on one surface of a non-magnetic filmy supporting body, and providing on the opposite surface a back layer contg. the globular powder of benzoguanamine.formaldehyde condensation-curing resin and a binder. CONSTITUTION:A magnetic body layer is provided on one surface of a non- magnetic filmy supporting body, and a back layer, contg. the globular powder of a benzoguanamine.formaldehyde condensation-curing resin having <=0.5mum mean particle diameter and a binder and having <=2mum film thickness, is formed on the opposite surface to obtain the recording medium. In this case, when the film thickness of the back layer exceeds 0.2mum, the thickness of the whole medium is unfavorably increased. Besides, when the mean particle diameter of the globular powder of the benzoguanamine.formaldehyde condensation-curing resin exceeds 0.5mum, the surface roughness is increased. Consequently, the magnetic recording medium, having a small coefficient of kinetic friction and excellent traveling durability and having the back layer capable of preventing a decrease in the S/N characteristic of the magnetic layer, can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording medium having a back layer having a small coefficient of dynamic friction, excellent running durability, and no reduction in wear.
In particular, it relates to magnetic tapes for audio, video tape recorders, and computers.

Conventional Structures and Their Problems In each of these types of magnetic tapes, in order to improve each characteristic, it was necessary to improve the smoothness of the surface of the magnetic layer. For this purpose, the film that is the support for the magnetic layer must also have excellent surface smoothness. However, in a tape in which a magnetic layer with excellent surface smoothness is provided on one side of a film support with excellent surface smoothness, the back surface of the film support also has excellent surface smoothness.

Magnetic tape, which has excellent surface smoothness on both sides, has a large coefficient of dynamic friction, and when it is unwound or rewound, it is not wound in an orderly manner and is prone to irregular winding, resulting in poor running performance and fluctuating output. It was something to do.

Furthermore, tapes for video tape recorders sometimes stop running.

In order to prevent this drawback, it may be possible to improve the running properties of the tape by providing a back layer on the surface of the film support opposite to the magnetic layer. However, when wound up, the surface smoothness of the magnetic layer may be impaired, and in particular, the S/N characteristics may deteriorate.

Purpose of the Invention The present invention has been made to solve these problems, and provides a magnetic recording medium having a back layer that has a small coefficient of dynamic friction, excellent running durability, and does not deteriorate the S/N characteristics of the magnetic layer. The purpose is to provide a medium.

Structure of the Invention To achieve this object, the magnetic recording medium of the present invention comprises a magnetic layer provided on one side of a non-magnetic film support, and a benzoguanamine formaldehyde layer with an average particle diameter of 0.5 μm or less provided on the opposite side. It is composed of a back layer containing spherical condensation cured resin powder and a binder and having a thickness of 2 μm or less.

Description of examples Examples of the present invention will be described below.

<Example> Polyethylene terephthalate 1 with a thickness of 15 μm (hereinafter referred to as P
(abbreviated as ET) on one side of the film containing Go-Fe20
3. A back layer was provided on the opposite side of the magnetic layer containing powder. The magnetic layer is made by dispersing the magnetic paint shown in Table 1 below using a one-ball mill, and then applying the gravure coating to a dry thickness of 6 μm.
The back layer was prepared by dispersing the paint composition shown in Table 2 below in a ball cell, and then applying gravure coating to give a thickness of 1 μm after drying.

(Table 1 below) The dynamic friction coefficient of the prototype tape was measured. As a result, the coefficient of dynamic friction of the PET surface without the back layer was 0.3 or more, and even when the tape was fed through a VHS video deck, feeding was poor and the video image quality was significantly degraded.On the other hand, the back layer of this example The coefficient of dynamic friction of the tape having the layer was 0.2 or less, and even when it was applied to a VHS video deck, tape feeding was stable and the video image quality was good.

Next, we prototyped a tape with the back layer composition shown in Table 2 and did not contain resin spherical powder, and measured the initial video SIN of the back layer with the composition shown in Table 2. When the resin spherical powder was included, it was +2.2 dB, and when it was not included, it was -2, OdB.

The binders in Table 2 are polyols for urethane resins, nitrocellulose, and polyincyanates. The binders in Table 1 are polyols for urethane resins, vinyl chloride/vinyl acetate copolymers, and polyisocyanates.

Here, if the thickness of the back layer exceeds 0.2 μm, the thickness of the entire medium becomes thick, which is undesirable. Furthermore, if the average particle diameter of the benzoguanamine/formaldehyde condensation cured resin spherical powder exceeds 0.6 μm, the surface roughness becomes rough, which is disadvantageous in terms of smoothness.

Effects of the Invention As described above, the present invention has a magnetic layer on one side of a non-magnetic film support having particularly excellent surface smoothness, and a benzoguanamine formaldehyde condensation cured layer having an average particle size of 0.5 μm or less on the other side. Contains resin spherical powder and binder, 2
The structure having a back layer having a thickness of μth or less has the effect of providing a magnetic recording medium with a small coefficient of dynamic friction and excellent running stability and durability.

Claims (1)

[Claims] A non-magnetic film support has a magnetic layer on one side, and the other side contains benzoguanamine formaldehyde condensation cured resin spherical powder with an average particle size of 0.5 μm or less and a binder, 2
A magnetic recording medium characterized by having a back layer having a thickness of μm or less.