JPS61273720A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the traveling stability and durability of the titled medium by providing a magnetic layer on one surface of a carrier and furnishing a layer contg. a specified silicon compd. on the other surface. CONSTITUTION:A silicon compd. shown by the formula is incorporated into a back-coat layer formed on the surface opposite to the surface on which a magnetic layer is formed. Since the silicon compd. shown by the formula has a fatty acid group having excellent affinity for a binder component in the molecule, the compatibility with the binder component is excellent. The residue of a saturated fatty acid of caprylic, capric, behenic acid, etc., or the residue of an unsaturated fatty acid of zoomaric, gadoleic acid, etc., is preferably used as the RCOO. About 0.5-4.5wt% silicon compd. shown by the formula is incorporated into the binder constituting the back-coat layer. Consequently, the traveling property of a recording medium is improved and the durability is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium such as a magnetic tape or a magnetic disk.

[Prior art and its problems]

In recent years, for example, home video tape recorders have become widespread and are used in a variety of environments, and along with this, magnetic recording media have also come to be used in a variety of environments.

The magnetic tape, which is the magnetic recording medium used in such video tape recorders, travels while coming into contact with a large number of guide pins from the device's loading mechanism, and is subject to considerable tension during this travel. There is.

Therefore, from the viewpoint of improving the running properties of the magnetic tape, that is, with the purpose of reducing the friction coefficient of the magnetic tape, a method of providing a so-called back coat layer was proposed (Japanese Patent Laid-Open No. 52-73703
．． 58-41420.59-5428).

That is, magnetic recording media have been proposed in which a back coat layer containing, for example, fluorine-modified silicone oil, carbon black, barium sulfate, etc. is provided on the surface of a nonmagnetic support opposite to the magnetic layer. However, it cannot be said to be sufficient, and has drawbacks such as poor unwinding at low temperatures.

[Disclosure of the invention]

As a result of research on the components contained in the back coat layer in magnetic recording media, the present inventor discovered that a silicon compound represented by the following general formula CA) may be included in the back coat layer. It was discovered that this magnetic recording medium has excellent running stability even under a wide range of environmental conditions, such as low temperature conditions.

(However, R is a saturated or unsaturated monovalent hydrocarbon group having 7 to 21 carbon atoms, R1, R-, Rs is CH, or RCoo,
R4 is a monovalent saturated hydrocarbon group having 1 to 20 carbon atoms, k, t
, m, and n are 1≦ and 1≦t<20o.

1≦-<200, O≦n(300, t+m+n≦500
In other words, the silicon compound represented by the general formula (A) contained in the so-called back coat layer has excellent compatibility with the binder and does not decompose even under high temperature and high humidity conditions. To provide a magnetic recording medium with high chemical stability and good running stability, and also to have an excellent lubricity effect even under low temperature conditions, and to provide a magnetic recording medium with good running stability. He found out.

In other words, the silicon compound represented by the general formula (A) has a fatty acid group in its molecule that has excellent affinity with the binder component, so it has good compatibility with the binder component.
Especially as RCOO, saturated fatty acid residues such as caprylic, capric, lauryl, myristyl, palmityl, stearyl, behenyl, or unsaturated fatty acid residues such as zomaryl, oleyl, linole, lilune, gadoleyl, etc.)
As mentioned above, since R in RCOO is a saturated or unsaturated hydrocarbon having 7 to 21 carbon atoms, it has excellent lubricity under both high-temperature and low-temperature conditions. In addition, if the number of carbon atoms in R is 6 or less, the lubricity under high temperature conditions is insufficient, and
When R has 22 or more carbon atoms, the compatibility with the binder component is poor, the slipperiness at low temperatures is insufficient, and the durability of the so-called back coat layer is also reduced.

Further, k, t, m, and n are 1≦, 1≦t<200.
1≦m (200%0≦n<300, t+m+n≦5
It must be an integer that satisfies the condition of 00, more preferably 1≦t≦100.1≦m≦100, 0≦n≦2
001t+m+n≦300.1≦k (t+m+
It is preferable that it also satisfies the condition n 11+m 0.1<□.

In other words, if L, m, and n become too large, or if k ) L + m + n, that is, if the molecular weight of the silicon compound represented by the general formula [A] becomes too large, the compatibility with the binder component will decrease. This is because the dispersibility of the silicon compound decreases, making it difficult to effectively exert the lubricity effect.

In addition, silicon compounds in the case of k = 0 have poor chemical stability, and for example, under conditions of high temperature and humidity, the so-called lubricating effect of the back coat layer is lost, and the durability of the back coat layer is reduced. becomes.

Further, when m is less than 1, the silicon compound has poor compatibility with the binder component, and the durability of the back coat layer is reduced during long-term running.

In addition, in the case of a silicon compound in the case of t+m -(0,1), the so-called backcoat layer does not have very good lubricity, and the durability of the backcoat layer tends to decrease.

The silicon compound represented by the above general formula CA) is preferably contained in an amount of about 0.5 to 4.5% by weight based on the binder constituting the so-called back coat layer. In other words, if the content of this silicon compound is too small, the effect will be weak, and if it is too large, the lubricity effect will be greater, but too much oozing to the surface will occur, causing blooming. This is because it becomes easier to wake up.

It is desirable that the so-called back coat layer consisting of a single layer of binder containing a silicon compound represented by the general formula (All) has a thickness of about 0.5 to 4 μm.

[Example 1] A silicon compound represented by the general formula [A] (provided that R
is C1 fist Hz+%R+ is CHs C00, R2 is C) (
, C.O.O.

R, is CH, R4 is C1°R21, k is 3, t is 10
0, m is 100, n is 200) 2 parts by weight, specific surface area 300 m''/g, DBP oil absorption 125 m17100
100 parts by weight of carbon black, 50 parts by weight of nitrocellulose, 50 parts by weight of polyurethane, 2 parts by weight of fatty acid ester, 450 parts by weight of a mixed solvent of equal amounts of methyl ethyl ketone, methyl isobutyl ketone and toluene were thoroughly mixed and dispersed using a sand mill. Add and mix 30 parts by weight of a polyisocyanate curing agent to this to make a paint, apply this paint to the side opposite to the magnetic layer forming side of the base film of the magnetic recording medium on which the magnetic layer is formed, dry it, and then A so-called back coat layer containing a silicon compound is formed to a thickness of approximately 0.8 to 1.5 μm through conventional steps such as acid treatment, thereby obtaining a magnetic recording medium such as a magnetic tape according to the present invention.

[Example 2] The same procedure as in Example 1 was carried out using 3 parts by weight of the silicon compound to obtain a magnetic recording medium according to the present invention.

[Example 3] The same procedure as in Example 1 was carried out using 40 parts by weight of nitrocellulose and 60 parts by weight of polyurethane to obtain a magnetic recording medium according to the present invention.

[Comparative Example 1] A magnetic recording medium is obtained in the same manner as in Example 1 without using any silicon compound.

〔Characteristic〕

Regarding the magnetic recording media such as magnetic tapes obtained on each side above, the coefficient of dynamic friction, the coefficient of dynamic friction after 500 reversing runs, the degree of scratching after 500 repeat runs, and the jitter are as shown in the table. It is.

The coefficient of kinetic friction (μk) was determined by wrapping a magnetic tape around a 6-diameter stainless steel bottle with the so-called back coat layer inside at a wrapping angle of 1800 mm, and using a pack tension of 50 g.
When running at a speed of 10 mx/S, the tension T1 on the inlet side and the tension T on the outlet side with respect to the stainless steel bottle! The value of the ratio T*/Tr r to μ=-4n (T
! /TI) π.

The degree of damage to the magnetic recording medium was determined by visually observing the degree of damage after repeated running 500 times.

The jitter was determined by running the screen repeatedly 100 times in an environment with a temperature of 40° C. and a humidity of 80% RH, and visually observing screen shake.

As can be seen from this table, the magnetic recording medium according to the present invention has a small coefficient of dynamic friction, is extremely less prone to scratches, has good running properties, and has been repeatedly tested for running. However, the running performance does not deteriorate that much, and it has excellent durability. Blooming is also less likely to occur, and the screen shake is extremely small.

〔effect〕

The magnetic recording medium according to the present invention has a special silicon compound interposed on the side of the support opposite to the magnetic layer, so that it has good running properties, has improved durability, and also has jitter. It is also possible to provide a magnetic recording medium with good recording and reproducing characteristics.

Claims (1)

[Scope of Claims] A magnetic recording medium comprising a magnetic layer on one side of a support and a layer containing a silicon compound represented by the following general formula on the other side. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R is a saturated or unsaturated monovalent hydrocarbon group with 7 to 21 carbon atoms, R_1, R_2, R_3 are CH_3 or R
COO, R_4 is a monovalent saturated hydrocarbon group having 1 to 20 carbon atoms, k, l, m, n are 1≦k, 1≦l<200, 1≦
An integer that satisfies the following conditions: m<200, 0≦n<300, l+m+n≦500)