JPS5954033A - 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 thioether of organosilicon compd. in a magnetic layer. CONSTITUTION:Magnetic powder such as gamma-Fe2O3 or Fe3O4, a binder such as PVC-vinyl acetate compolymer, polyurethane resin 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 7-21C monovalent hydrocarbon; R2 is 1-4C monovalent hydrocarbon; (k) is 1-12; (l) is 1-6; (m) is 1, 2; (n) is 0, 1, 2; (m + n)<=3) is added at about 0.1-15wt% to the magnetic powder and both are mixed. The resulting 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 incorporating a specific thioether organosilicon compound into the magnetic layer, the lubricity and abrasion resistance of the magnetic layer are improved, and the running stability is improved. The purpose of the present invention is to provide a magnetic recording medium that has excellent properties.

In recent years, home video 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 dynamic friction coefficient of the magnetic layer increases significantly, further worsening the runnability.

Conventionally, for the purpose of reducing friction of magnetic recording media, higher fatty acids, dimethyl silicone, or general formula (1),
(It has been proposed to improve the lubricity of the magnetic layer by adding an organic silicon compound expressed in ml.

CH30H20H-S i (OOOR).
(11(CH3)3-r, 1 (CH3) n F(OF2)n(OH2)tS i (OR)3-n
(II) However, what is added to the magnetic layer is high-grade fat I.
In the case of I/j acids, higher fatty acids have good compatibility with the resin component in the magnetic layer and exhibit some degree of lubricating effect, but higher fatty acids tend to be adsorbed to the magnetic powder and therefore ooze out onto the surface of the magnetic layer. It has the drawbacks that it is difficult to use, has little effect on lowering the coefficient of dynamic friction on the surface of the magnetic layer, and is easily affected 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.

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

The general formula (■) has been proposed as an alternative to higher fatty acids such as dimethyl silicone.
(Special Publication No. 52-34924) or (II) (% Kaisho 5
No. 7-92424), these organosilicon compounds have excellent lubricity and have a stable coefficient of friction against temperature changes, but their compatibility with the resin component in the magnetic layer is poor. It cannot be said that it is sufficient, and it is not that satisfying.

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, etc., has excellent compatibility with the resin component in the magnetic layer, and is not easily affected by temperature changes. As a result of continued research into lubricants, it was discovered that an organosilicon compound represented by the following general formula (m) is extremely satisfactory and does not have the above-mentioned drawbacks.

(OH3)3-,,-・F (OF2)kOH2C1(28(OI(2)z
S + (ocoRI) m (+n) (OHn) (However, R is a monovalent hydrocarbon group having 7 to 21 carbon atoms, R2
is a monovalent hydrocarbon group having 1 to 4 carbon atoms, k is an integer of 1 to 12, t is an integer of 1 to 6, m is 1 or 2, □n is 0,
1 or 2, satisfying the conditions of n+m≦3) The organosilicon compound represented by the general formula (Ill) is
Compared to the organosilicon compounds represented by the general formulas (+1 and (It)), it has excellent durability and is less likely to cause contamination of the magnetic head;
This is thought to be due to the presence of a thioether group represented by -8- in the compound of 1.

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, improves durability, and is less likely to cause contamination of the magnetic head. There are also things.

Such an organosilicon compound is effective if it is included in the magnetic layer in an amount of about 0.1 parts or more overlapped with the magnetic powder, and the effect becomes more pronounced as the content increases. However, if it is present in large quantities in excess of about 15 overlapping parts, it can cause contamination of the magnetic head and excessive plasticization of the magnetic coating. Those within the range of .5iE quantity coefficient are likely to be a-+.

In the same general formula (l, if the number of carbon atoms in R1 is less than 7, the effect of reducing the friction coefficient and durability is small, and R3
If the number of carbon atoms exceeds 21, the compatibility with the resin component in the magnetic layer becomes poor, and the magnetic head is likely to be contaminated. Furthermore, when the number of carbon atoms in R2 exceeds 4, the affinity with the magnetic powder and binder resin component in the magnetic layer decreases, making it easy to cause contamination of the magnetic head.
Furthermore, the durability of the magnetic layer tends to decrease. Also, 1
(If it exceeds 12, the compatibility with the binder resin component etc. will be poor and the magnetic head will be likely to be contaminated.

Similarly, there are no special restrictions on the components contained in the magnetic layer other than the general formula (III) used in the present invention, and examples of the magnetic powder include, for example, γ-Fe2O3
, Fe, , 04 , Co-containing 7-Fe, 03, metal, etc., and binders include, for example, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane resin, nitrocellulose, epoxy resin, etc. Examples of organic solvents for making magnetic paints include toluene, methyl ethyl ketone, methyl isobutyl ketone, nclohexanone, and tetrahydrofuran.

Hereinafter, some specific examples of the magnetic recording medium according to the present invention will be described.

Example I CO-containing - Approximately 100 parts of Fe203, vinyl chloride -
About 19 parts by weight of a mixture of vinyl acetate-vinyl alcohol copolymer and polyurethane elastomer, about 5 parts by weight of carbon black, about 1110 parts by weight of soybean lecithin, about 270 parts by weight of a mixed solvent of methyl ethyl ketone, methyl isobutyl ketone and toluene, and OF30 H20H2S.
(OH2) 0C expressed as 3S + OOOO9I-119! After mixing and dispersing a mixture of up to about 15 parts by weight, e.g. 2 parts by weight, of the organosilicon compound to be rounded for about 20 hours, about 8 parts by weight of polyisocyanate (for example, D-103H from Takeda Pharmaceutical Co., Ltd.) is added. A magnetic paint is applied onto a polyester film, calendered, heat treated 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 Instead of the organosilicon compound in Example 1, 04F 90II20H2S (OH2) 2S
A magnetic tape is obtained in the same manner as in Example 1 using i(OOOQ3 H27)2.

Example 3 Instead of the organosilicon compound in Example 1, a4 y;
”9 cr (2c1.L S (cl-12)
3 81 (000013H27)2 0C
4I].

A magnetic tape is obtained in the same manner as in Actual MIj Example 1.

Example 4 Instead of the organosilicon compound in Example 1, 04F9C
1-■2C■-12-8-(OH2)3-81-oco
c1□H35ヲのい(OC■13)2 Then, in the same manner as in Example 1, a magnetic tape was obtained.

Example 5 A magnetic tape is obtained in the same manner as in Example 1, except that the organosilicon compound used in Example 1 is replaced.

Example 6 Instead of the organosilicon compound in Example 1, OH3O8F17CH2CH2-8-(CH2)6-8l-(
OCoC15I-■3. )2 to obtain a magnetic tape in the same manner as in Example 1.

Example 7 Instead of the organosilicon compound in Example 1, 0.2F2
50H20H2-8-(OH2) 2-8 i -(Q
C! A magnetic tape is obtained in the same manner as in Example 1 using CH3 and 002□l-I43).

Comparative Example 1 A magnetic tape was obtained in the same manner as in Example 1 except that butyl stearate was used in place of the organosilicon compound in Example 1.

Comparative Example 2 Instead of the organosilicon compound in Example 1, OH3 0F30H,0H2-8i -(0000,5H3,)
A magnetic tape is obtained in the same manner as in Example 1 using Example 2.

Comparative Example 3 Instead of the organosilicon compound in Example 1, 1-13 C3li'', 7C14201-12-8i -(000
A magnetic tape is obtained in the same manner as in Example 1 using C7yH33)2.

The magnetic tape obtained in this way was tested at a temperature of 60°C.
The magnetic tape was installed in a magnetic recording and production apparatus under environmental conditions of 90° C. and relative humidity of 90 parts, and a magnetic tape was repeatedly run 400 times. As a result, the characteristics shown in the table were obtained.

Table: S/N deterioration is indicated by the difference between SIN 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 means very little dirt, 13 means little dirt, C means a lot of dirt, D means very much dirt and surrounding The drum also shows how dirty it is.

As can be seen from these results, in Comparative Example 1, although head contamination was relatively small and the deterioration of SIN was relatively small, the coefficient of dynamic friction was large;
Comparative Examples 2 and 3 had relatively low coefficients of dynamic friction, and although relatively good running stability was achieved, head contamination was severe and S was greatly degraded.

On the other hand, in Examples 1 to 7, there was little head contamination, the SIN deteriorated little even after repeated running tests, and the dynamic friction coefficient was low and stable. It exhibits excellent characteristics such as running stability and magnetic properties.

In particular, severe environmental conditions such as 60℃, 90% II, H (
11) It has excellent running stability even when used for a long time under injection, and is unlikely to cause problems such as head contamination.

As mentioned above, the magnetic recording medium according to the present invention contains the following general formula % formula % (2) (where (7.1%) is a monovalent hydrocarbon group having 7 to 21 carbon atoms,
I′L2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms;
12 integers, t is an integer from 1 to 6, m is 1 or 2, n is 0
, ■ or 2, m+n≦3), the running properties are stable even under harsh environmental conditions, that is, the coefficient of dynamic friction is low and stable over a wide temperature range, and The decrease in S is small even after repeated running, and the magnetic head is not easily contaminated.
Furthermore, it has features such as a highly durable magnetic layer.

(12)

Claims (1)

[Claims] In the magnetic layer, the following general formula % formula % (wherein R1 is a monovalent hydrocarbon group having 7 to 21 carbon atoms, R2
is a monovalent hydrocarbon group having 1 to 4 carbon atoms, 1 (is an integer of 1 to 12, t is an integer of 1 to 6, m is 1 or 2, η is 0.1 or 2, m+n≦3) A magnetic recording medium characterized in that it contains an organic silicon compound.