JPS5954035A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the lubricity and wear resistance of a magnetic layer and to improve the running stability of a magnetic recording medium by incorporating a specific organosilicon compd. in the magnetic layer. CONSTITUTION:Magnetic powder such as gamma-Fe2O3 or Fe3O4, a binder such as PVC-vinyl acetat copolymer, polyurethane or the like and an org. solvent (e.g.; toluene), etc. are mixed. The organosilicon compd. (e.g.; formula II, formula III) expressed by the formula I (R1 is satd. or unsatd. monovalent hydrocarbon; R2 is satd. 1-4C monovalent hydrocarbon; (j) is 1-12; (k) is <2<=0; (m) is <2.5, (l) is <=1; (n) is <=2; (k + l + m + n) is 2-3; the carbon atoms of silicon in one molecule are 2-300) is added at about 0.1-15wt% to the magnetic powder and both are mixed. The resulted magnetic coating is coated on a substrate such as polyester film and is dried to form a magnetic layer, whereby the intended magnetic recording medium is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and by including a specific organic silicon compound in the magnetic layer, the lubricity and abrasion resistance of the magnetic layer are improved, and the running stability is improved. The purpose is to provide an excellent magnetic recording medium.

In recent years, home video tape recorders have become smaller and more frequently used outdoors. Therefore, the magnetic recording media used in these magnetic recording and reproducing devices are required to have a quality that can withstand use under various environmental conditions, such as over a wide temperature range. For example, there is the problem of runnability, which is easily affected by temperature, and especially under low temperature conditions, the coefficient of dynamic friction of the magnetic layer increases significantly, making the runnability even worse.

Conventionally, in order to reduce the friction of magnetic recording media, higher fatty acids, dimethyl silicone, or the general formula (IL
It has been proposed to improve the lubricity of the magnetic layer by adding an organic silicon compound represented by (II).

0F30H20H2S i (OOOFt)
(1)(CH3)3-rn (CI(3)n F(OF,) (Of-L)tSi (OR)3-n
(II) However, when the substance added to the magnetic layer is a higher fatty acid, the higher fatty acid has good compatibility with the resin component in the magnetic layer and exhibits a lubricating effect to some extent. It has the drawbacks that it is easily adsorbed and therefore oozes out onto the surface of the magnetic layer, has little effect on lowering the coefficient of dynamic friction on the surface of the magnetic layer, and is easily influenced by temperature.

In addition, when dimethyl silicone is used, although it has a great effect on the surface smoothness of the magnetic layer, it has poor compatibility with the resin component in the magnetic layer and easily oozes out from the surface of the magnetic layer. When a magnetic recording medium is used repeatedly, the coefficient of dynamic friction gradually increases, and the running performance and wear resistance deteriorate.

Furthermore, it also has the disadvantage that it tends to cause contamination of the magnetic head, which adversely affects recording and reproduction.

The above-mentioned general formula (■) (
Japanese Patent Publication No. 52-34924) or (If) (Japanese Patent Publication No. 57
-92424), these organosilicon compounds have excellent lubricity and have a stable coefficient of friction against temperature changes, but they do not have sufficient compatibility with the resin component in the magnetic layer. It cannot be said that it is, and it is not very satisfactory.

The present inventor has discovered that even when added to the magnetic layer of a magnetic recording medium, it does not deteriorate the magnetic properties, has excellent compatibility with the resin component in the magnetic layer, and is resistant to temperature changes. As a result of continuing research into lubricants that are less susceptible to
It has been found that an organosilicon compound represented by the following compositional formula (n+) is extremely satisfactory and does not have the above-mentioned drawbacks.

(OH3),, 'CF (0F2)4' 01lf
OIT2〕7'(&000?n'(R,O)n'S
io q(III) (However, R1 is a saturated or unsaturated monovalent hydrocarbon group having 7 to 21 carbon atoms, R2 is a saturated monovalent hydrocarbon group having 1 to 4 carbon atoms, and j is an integer of 1 to 12. ,0≦k<2.0<m<
2.5, o<t≦1, O(n≦2.2≦k +l-1
-m + n≦3.1 Number of silicon atoms in molecule is 2 to 300
The organosilicon compound represented by the formula (Ill) has excellent durability compared to the organosilicon compounds represented by the general formulas (■) and (II), and is less likely to contaminate the magnetic head. It is difficult to cause.

In addition, since this organosilicon compound has a fluorinated hydrocarbon group, it not only has an excellent lubricity effect but also has good thermal stability and is durable and does not cause contamination of magnetic fields. It is also difficult.

Such an organosilicon compound is effective if it is contained in an amount of about 0.1% by weight or more based on the magnetic powder in the magnetic layer, and the effect becomes even more pronounced as the content increases. However, if the content exceeds about 15%, it may cause contamination of the magnetic head and excessive plasticization of the magnetic coating. Preferably within the department.

In 2 (III), when k becomes 2 or more, relatively [F (CF2), CH2CH2], (R,,000)
As the concentration of
When m exceeds 25, the compatibility with the binder resin decreases, and when m exceeds 25, CF, (
Since the concentration of CF'2)1C1-120H2) and (R,20) decreases, durability decreases, and when n exceeds 2, CF (OF2) JOI-L
0I-I2], because the concentration of (R,000) decreases,
The slipperiness becomes insufficient.

Furthermore, the organosilicon compound represented by the average compositional formula (■) may have a linear, branched chain, or cyclic molecular structure.

Similarly, there are no particular restrictions on the components that can be included in the magnetic layer other than the organosilicon compound used in the present invention, and examples of the magnetic powder include γ-Fc203,
There are Fe3O4, Co-containing 7-Fe2O3, metals, etc., and binders include vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane resin, nitrocellulose, epoxy resin, etc., and magnetic paints are also made. For example, toluene,
Examples include methyl ethyl ketone, methyl imbutyl ketone, cyclohexanone, and tetrahydrofuran.

Some specific examples of the magnetic recording medium according to the present invention will be described below.

Example 1 Approximately 100 parts by weight of 0o-containing γ-Fe203, vinyl chloride
About 19 parts by weight of a mixture of vinyl acetate-vinyl alcohol copolymer and polyurethane distomer, about 5 parts by weight of carbon black, about 1 part by weight of soybean lecithin, about 270 parts by weight of a mixed solvent of methyl ethyl ketone, methyl isobutyl ketone and toluene, and (C■(s)1.3 (OF
s CL OH2)0.2 (Or ? Hss Co
O) C5(OHs O) o,z S Io o,
9 (Si number is 10) about 19 parts by weight or more T1 For example, after mixing and dispersing a mixture of 2 parts by weight for about 20 hours, about 8
parts by weight, this magnetic paint is applied onto a polyester film, calendered, heated at about 55° C. for about 24 hours, and slit to a predetermined width to obtain a magnetic tape for, for example, a video tape recorder.

Example 2 A 1-comb tape was obtained in the same manner as in Example 1, using (Si number: 15) instead of the organosilicon compound in Example 1.

Example 3 Instead of the organosilicon compound in Example 1, (') [
' s ) 1.2 (0+ F o OH20l-12
). 3 (CIT Hs+ 000). ,5 (0
A magnetic tape is obtained in the same manner as in Example 1 using 411oO) 62S 1oo9 (Sl number is 10).

Example 4 Instead of the organosilicon compound in Example 1, (0IIP
)147 (C8F 1701T+C41-), (O
v I], scoo). 3(OHs O)o,C
A magnetic tape is obtained in the same manner as in Example 1 using 5S io C99 (Si number is 100).

Example 5 Instead of the organosilicon compound in Example 1, (0127
”250H2(III2).6(OQTI,,Co
o) A magnetic tape is obtained in the same manner as in Example 1 using 2(02H50)oa5ino8 (Si number is 5).

Example 6 Instead of the organosilicon compound in Example 1, (0113
) CO,F, 0020H2)(a,,■(27CO
O). 5 (CIJ, 0). 5SiOo5 (Si number is 2)
A magnetic tape is obtained in the same manner as in Example 1.

Comparative Example 1 A magnetic tape was obtained using butyl stearate instead of the organosilicon compound in Example 1.

Comparative example 2 In place of the organosilicon compound in Example 1, OH.

Tsuta OF30H2C' H2S I (000015H31
) 2 to obtain a magnetic tape in the same manner as in Example 1.

Comparative Example 3 Instead of the organosilicon compound in Example 1, OH3 ■ 08F17CH2CH2S1 (oCOC17H33)2
A magnetic tape was obtained in the same manner as in Example 1.

The magnetic tape obtained in this way was tested at a temperature of 60°C.
C. and a relative humidity of 90%, the magnetic tape was mounted on a magnetic recording and reproducing apparatus and tested for running 400 times, and the results showed the characteristics shown in the table.

・S/N degradation is indicated by the difference between S/N before the driving test and S after the driving test.

・Head contamination is determined by observing the magnetic head with an optical microscope after a running test and displaying it in 4 levels: A is very little contamination, B is very little contamination, C is a lot of contamination, and D is very much contamination. It also shows how dirty the surrounding drums are.

As can be seen from these results, in the case of Comparative Example 1, there was relatively little head contamination and the deterioration of S/N was relatively small, but the dynamic friction coefficient was large and the running stability was poor. In addition, in Comparative Examples 2 and 3, the coefficient of dynamic friction was relatively small, and although running stability was obtained,
Head contamination is severe, and the S/N ratio is also severely degraded. On the other hand, in Examples 1 to 6, there was little head contamination, the deterioration of S/N was small even after repeated running tests, and the coefficient of dynamic friction was also stable. In addition, it exhibits excellent running stability and magnetic properties. In particular, even when used for a long time under severe environmental conditions such as 60° C., 90φR, LT, it has excellent running stability and is unlikely to cause problems such as head contamination.

As described above, the magnetic recording medium according to the present invention has the following compositional formula (%) in the magnetic layer (where R1 is a saturated or unsaturated (1
1) Monovalent hydrocarbon group, R2 is a saturated monovalent hydrocarbon group having 1 to 4 carbon atoms, J is an integer from 1 to 12, k is a number of 0 or more but less than 2, and m is less than 2.5. , t is a positive number less than or equal to 1, n is 2
The following positive numbers, k+7-1-m+n, are numbers from 2 to 3, and the number of silicon atoms in one molecule is from 2 to 300), so the running properties are stable even under harsh environmental conditions. In other words, the coefficient of dynamic friction is low and stable over a wide temperature range, the decrease in S is small even after repeated running tests, and the magnetic head is not easily contaminated. It has features such as being highly durable.

Claims (1)

[Scope of Claims] In the magnetic layer, the following compositional formula % formula % (where Ro is a monovalent hydrocarbon group having 7 to 21 carbon atoms, saturated or unsaturated, and R2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms) Saturated monovalent hydrocarbon group, j is an integer from 1 to 12, 1 (is a number greater than or equal to 0 and less than 2, m is a positive number less than 2.5, t is a positive number less than or equal to 1, n is 2
The following positive numbers, k IL +m+n are numbers from 2 to 3, 1
1. A magnetic recording medium comprising an organosilicon compound having 2 to 300 silicon atoms in the molecule.