JPS5994233A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the wear resistance and lubricity of a magnetic recording medium by incorporating a fluorinated alkyl ether group [0(CH2)i(CF2)j] in the side chain in an organopolysiloxane compd. CONSTITUTION:A magnetic recording medium holds the organopolysiloxane compd. expressed by the general formula. If the carbon atom of R<1>, R<3>, R<5>, R<6> is <7 in the formula I , the coefft. of friction is not decreased and durability is decreased. When said number exceeds 21, a decrease in the solubility in a magnetic layer and an increase in a m.p. arise. When (j) exceeds 12 with respect to the F-contg. hydrocarbon group (CF2)j, a decrease in the solubility in the magnetic layer and a rise in the m. p. arise and if (j) is 0, the coefft. of friction decreases. When (l), (m) and (n) exceed 300, the compatibility with the magnetic layer is poor. Therefore (l+m+n)<600 is preferred. The concn. of ester is preferably m/(2+l+m+n)>=0.05. The organopolysiloxane lubricant to be used is preferably added at 0.5-7pts.wt. (PHP) in 100pts. the magnetic powder in a magnetic layer in the case of incorporating the same in said layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium having a magnetic layer on a support, such as a magnetic tape or a magnetic disk.

In particular, magnetic tapes are required to have various characteristics, including a low coefficient of friction, smooth and stable running, a small amount of powder falling off, and good splicability. That is, when magnetic tape is used in magnetic recording and reproducing devices such as VTRs, it runs at high speed while physically contacting tape guides, magnetic heads, etc., so it has excellent wear resistance and remains stable over long periods of time. It is important to be able to drive in For example, if the friction coefficient of the tape surface changes during recording or reproduction, the tape will vibrate at the guide or magnetic head. As a result, the frequency of the recorded/playback signal (for example, an audio signal) on the tape changes, resulting in a sound that is different from the wave number, or the vibration sound of the tape (so-called Q sound) can be directly heard. There is.

In order to prevent this, various attempts have been made to impart lubricity to the tape. For example, γ-F8203
A solid lubricant such as molybdenum disulfide, graphite, wax, etc. is added to a magnetic paint containing magnetic powder and a vinyl chloride binder. Only A.

This solid lubricant is undesirable because it is not very effective in improving durability and, when added in large amounts, deteriorates magnetic properties. On the other hand, higher fatty acids, higher fatty esters,
Paraffinic hydrocarbons, silicone oils (e.g. dimethyl silicone oil, diphenyl silicone oil)
etc. may be used as a lubricant, but even this cannot provide sufficient durability and lubricity, and is particularly insufficient for use in VTR cassettes. Moreover, blooming in which the lubricant oozes onto the surface of the magnetic layer is likely to occur, causing tape sticking, stick-slip, and the like.

In view of the above-mentioned points, the present invention provides a magnetic recording medium that has improved tape running stability, wear resistance, and reduced coefficient of friction.

In the present invention, in a magnetic recording medium having a magnetic layer on a support, this magnetic recording medium has a general formula (where X is 10COR'', -R20COR3, -R
'COOI (5 or -86 COOH, R1,
R3 and R5 are saturated or unsaturated monovalent hydrocarbon groups having 7 to 21 carbon atoms, R2 and R4 are saturated or unsaturated divalent hydrocarbon groups having 1 to 21 carbon atoms, and R6 is a saturated or unsaturated divalent hydrocarbon group having 7 to 21 carbon atoms. It is a saturated divalent hydrocarbon group. A1 and A2 are -(j13.0
(CI+2); (CF2)j is one selected from Y or X, i is 0, ■ or 2, j is an integer from 1 to 12, and Y is a hydrogen atom or a fluorine atom. 11m and n are both integers from O to 300, and A1 or A2 is
In this case, j2=0 and m=o, and if A1 or A2 is -0(CH2) Ic JF 2J +1, then J=
0, n=0 is also possible, and if both A 1 and A 2 are −CH3, it is 7! It may be -0, but neither m nor n must be O. ) The present invention relates to a magnetic recording medium characterized by containing an organopolysiloxane compound represented by:

A magnetic recording medium configured in this manner not only has good wear resistance, but also has a small friction coefficient and improved lubricity, providing smooth and stable running performance. That is, the above-mentioned organopolysiloxane compound has a fluorinated alkyl ether group [(CH2) 1(CF2)] in the side chain in the structural formula.
j), the coefficient of friction becomes sufficiently small,
Characteristics also improve.

In the above structural formula, if the number of carbon atoms in R1, R3, R5, and R6 is less than 7, the friction coefficient will not decrease and the durability will decrease, and if it exceeds 21, the solubility in the magnetic layer will decrease and the melting point This increases the likelihood of blooming. R2,
The reason why the number of carbon atoms in R4 is set to 21 or less is due to the same reason. Regarding the F-containing hydrocarbon group (CF2), j is set to 1 to 12 or less because if it exceeds 12, the solubility in the magnetic layer will decrease and the melting point will increase, making it easier to cause blooming and head staining. It is. When j is O, the friction coefficient decreases and the effect becomes less effective. l, m, and n to 300
The reason why the molecular weight is set below is that if it exceeds 300, the molecular weight becomes too high and the compatibility with the magnetic layer deteriorates. Therefore, z+
It is preferable that m+n<600. Further, the concentration of X (ester) is preferably ≧0.05 2+g+m+n.

In order to fully exhibit the above-mentioned effects, the amount of the organopolysiloxane lubricant used in the present invention is 0.5 to 0.5 to 0.5 to 0.5 parts by weight of the magnetic powder in the magnetic layer when it is included in the magnetic layer. Preferably, the amount is 7 parts by weight (PHP). When it is included in the bank coat layer (described later) on the back side of the base, it is preferably 0.5 to 20 parts by weight (PHR) per 100 parts by weight of the binder in the back coat layer. Further, when a top coat layer or a coating layer (both described below) made of the above-mentioned lubricant is applied, the amount of the lubricant applied is preferably 1 to 1000 .mu./i.

Next, a specific example of the method for synthesizing this organopolysiloxane compound will be explained.

Example of fl + dehydrogenation reaction CHa CHa X HGLI (However, A1, A2, and X are the same as above) St −
H-containing compound, 110(CH2), (CF2)・Y(
It is synthesized by dehydrogenating the alcohol represented by (I, j, Y are the same as above).

(2) Example CI (a CHa X CQ
(:T(a (however, AI, A2, and X are the same as above)) and the St-(J-containing compound and
It is synthesized by dehydrochlorination reaction with the alcohol represented by i'(CF2)J'Y (where i, j+Y are the same as above).

A magnetic recording medium, such as a magnetic tape, according to the present invention is illustrated in FIGS. 1 to 5.

Figure 1 shows a non-magnetic base (11) with a magnetic layer (2) containing the lubricant of the present invention formed on the surface thereof. Figure 2 shows a top coat layer (3) made of a lubricant according to the present invention formed on the surface of a magnetic layer (2). Figure 3 shows a top coat layer (3) made of a lubricant according to the present invention. Coating layer (4) consisting of a lubricant according to the present invention on the back side of (1)
This shows the state in which a is formed. Figure 4 shows the non-magnetic base +1
FIG. 5 shows a state in which the lubricant according to the present invention is contained in the bank coat layer (5) formed on the back surface of
A coating layer (6) made of a lubricant according to the present invention is shown formed on a bank coat layer (5). The bank coat layer (5) is provided for various purposes, including stabilizing running properties by appropriately controlling the surface roughness of the bank surface, and preventing static electricity. For this reason, the back coat layer may be coated with a binder mixed with carbon black, or may further contain a nonmagnetic pigment such as α-Fe20a, alumina, talc, etc. The magnetic recording medium of the present invention can be applied not only to such magnetic tapes but also to magnetic disks having magnetic layers on the front or back surfaces. Also, among FIGS. 1 to 5, for example, a combination of FIG. 1 and FIGS. 2 to 5, a combination of FIG. 2 and FIGS. 3 to 5, and a combination of FIGS. and the fourth
The lubricant according to the present invention can be held at various positions in the magnetic layer (2) or on the front and/or back surface of the magnetic layer (2), as shown in FIG. I can do it.

Ferromagnetic powder (magnetic powder) that can be used in the magnetic layer of the present invention includes r -Fe20as Fea04, T -Fe2
Mixed crystal of 0a and Pe30+, cobalt-doped γ-
Fe20a −.

Fea04 doped with cobalt, chromium dioxide, barium ferrite, various alloy powder magnetic materials (e.g. Fe-
Co, Go-Ni% Fe-Go-Nis Fe-
Co-Bs re-G.

-Cr-Bs Mn-B1,, Mn-Al%F
e-Go-V, etc.), iron nitride, etc., and two or more of these may be used in combination. Binders that can be used in the magnetic layer include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol, vinyl chloride-vinyl acetate-maleic acid copolymer, and vinyl chloride-vinylidene chloride copolymer. Coalescence, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic ester-vinylidene chloride copolymer, methacrylic ester-styrene copolymer, thermoplastic Polyurethane resin, phenoxy resin polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-acrylic acid copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyvinyl butyral, polyvinyl acetal , cellulose derivatives, styrene-butadiene copolymers, polyester resins, phenol-O resins, epoxy resins, thermosetting polyurethane resins, urea resins, melamine resins, alkyd resins, urea-formaldehyde resins, and the like. In addition, examples of reinforcing materials that can be used in the magnetic layer include aluminum oxide, chromium oxide, silicon oxide, etc. alone or in combination. Furthermore, conventionally known fine particulate carbon black can be used as an antistatic agent, and lecithin can be used as a dispersant.

When preparing magnetic paint, use acetone, methyl ethyl ketone, methyl isobutyl ketone,
Ketones such as cyclohexanone; alcohols such as methanol, ethanol, propatool, butanol; esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol acetate, monoethyl ether; ethylene glycol dimethyl ether, ethylene glycol monoethyl Glycol ethers such as ether and dioxane; aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as hexane and heptane; nitropropane and the like can be used alone or as a mixture. Non-magnetic bases for applying magnetic paint prepared with this organic solvent include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene,
Examples include cellulose derivatives such as cellulose triacetate and cellulose diacetate, polycarbonate, polyvinyl chloride, polyimide, metal materials such as aluminum and copper, and paper. In addition, Freon,
Weakly polar, low boiling point solvents such as hexane and ethanol may be used.

Furthermore, magnetic recording media to which the organopolysiloxane compound of the present invention is applied as a lubricant are not limited to so-called coating-type magnetic recording media in which a magnetic layer is formed by applying magnetic powder together with a binder as described above, but also include metal thin film. This also applies to type magnetic recording media. This metal thin film magnetic recording medium has a magnetic metal such as COXFe, N
1 or an alloy thereof using a so-called physical vapor deposition (PVD) technique such as vacuum evaporation, ion blasting, or sputtering, or a liquid phase plating technique. This metal thin film type magnetic recording medium has a high magnetic flux density because it does not require the use of a binder, and since it is formed into a very thin layer, it is useful for short wavelength, high density recording.

Hereinafter, the present invention will be explained in detail with reference to examples.

First, examples of synthesis of the lubricant made of the organopolysiloxane compound used in this example are listed in the table below.

3 2 4 5 16 Next, the composition and characteristics of the magnetic paint common to this example were as follows.

r-Pe20a 100
Parts by weight Vinyl chloride-vinyl acetate copolymerization 18 Parts by weight (TL, C, C, VAGH manufactured by Co., Ltd.) Polyurethane resin (B, P, Gutsud) 12 Parts by weight Vinyl chloride-vinyl acetate copolymerization Carbon (antistatic agent) 0 .5 parts by weight Lecithin (dispersant) 1.0 parts by weight Lubricant (see below) Methyl ethyl ketone (solvent) 150 parts by weight Methyl isobutyl ketone (solvent) 150 parts by weight Mix these raw materials in a ball mill for 24 hours, then The mixture was taken out through a filter, and immediately before coating, 3 parts by weight of an isocyanate compound was added and stirred for 30 minutes. This mixture was applied onto a polyethylene terephthalate base having a thickness of 12 μm so that the thickness after drying would be 5 μm, followed by orientation, drying, and winding. After surface treatment, this was cut into a sample tape with a width of about an inch.

Examples 1 to 10 Examples 1 to 10 were sample tapes in which 2.0 PHP (coulometric parts) of each of the ten organopolysiloxane compounds of Synthesis Examples 1 to 1O were added to magnetic powder.

Comparative Examples 1 and 2 As a lubricant, dimethyl silicone oil (Comparative Example 1),
Sample tapes were prepared using each of the methylphenyl silicone oils (Comparative Example 2).

Reference Example 1 A C sample tape was prepared using the organopolysiloxane compound of Synthesis Example 11 (n-500 in Synthesis Example 10).

When the characteristics of the tape on each side were compared, the results shown in the table below were obtained.

90 From this data, it can be seen that if the lubricant according to this example is used, the friction coefficient is reduced, running stability is achieved, and the amount of powder falling off is also small. In addition, from Reference Example 1, when the value of n in the structural formula of the above-mentioned organopolysiloxane is too large, there is a tendency that the amount of powder falling off increases.

Example 11 A magnetic layer was formed by vacuum evaporating CO to a thickness of 1000 mm on a base made of polyethylene terephthalate having a thickness of 12 μm by an oblique evaporation method. A 1% Freon solution of the organopolysiloxane of Synthesis Example 3 was applied onto the magnetic layer thus formed so that the coating amount of the organopolysiloxane was 20 mg/
It was applied (top coat) so that it became rd. The sample tape obtained in this manner was designated as Example 11. In addition, comparative example 3
Sample tapes were prepared without any top coat treatment using the organopolysiloxane of Example 11, and the friction coefficient μd and occurrence of scratches on the magnetic surface are shown in the table below.

I Example 12 A 12μ magnetic paint was obtained by removing the lubricant from the above magnetic paint composition.
A magnetic layer was formed by coating a 5 μm thick polyethylene terephthalate base. A 1% Freon solution of the organopolysiloxane of Synthesis Example 1 was coated (top coated) on this magnetic layer so that the coating amount of the organopolysiloxane was 80 mg/rrl. The magnetic tape thus obtained had a friction coefficient μd of 0.180.

As Comparative Example 4, the sample tape of Example 12 which was not top coated with organopolysiloxane had a friction coefficient μd of 0.420.

Example 13 2 The sample tape of Example 7 using Synthesis Example 7 above as a lubricant and the sample tape (Comparative Example 4) using the following organopolysiloxane compound CF3C-0C17Has as a lubricant. Comparative Example 14 The following components: Carbon 100 parts by weight Polyurethane resin 50 parts by weight (Nistan 5
702) Epoxy resin 50 parts by weight (Epicron 351 manufactured by Dainippon Ink ■) Pickling agent (Synthesis Example 2) 4 parts by weight Methyl ethyl ketone 400 parts Triol After mixing 400 parts by weight,
20 parts by weight of Dismodule L was added to prepare a back coat paint. Example 14 was a sample tape in which this paint was applied to the back surface of the base so that the thickness after drying was 3 μm to form a back coat layer (5) (see FIG. 4).

Comparative Example 5 A sample tape was prepared by applying a paint obtained by removing only the lubricant component from the back coat paint shown in Example 14 to the back surface of a base to form a back coat layer.

Example 15 A 1% Freon solution of the organopolysiloxane of Synthesis Example 5 was applied onto the bank coat layer of Comparative Example 5 so that the coating amount of the organopolysiloxane was 80 mg/rrr to form a coating layer (4) (No. Example 15 was a sample tape obtained by forming a sample tape (see Figure 5).

Comparative Example 6 A sample tape was prepared from Example 15 except that the coating layer (4) was removed.

Example 16 A 12μ magnetic paint was prepared by removing the lubricant from the magnetic paint composition described above.
A magnetic layer was formed by coating a thick polyethylene terephthalate base to a thickness of 5μ, and the above Synthesis Example 1 was coated on the back of the base.
A sample tape was prepared by applying a 1% Freon solution of 0 organopolysiloxane so that the coating amount of organopolysiloxane was 2 mg/+y+ to form a coating layer (4) (see FIG. 3). It was set at 16.

Comparative Example 7 A sample tape was prepared from Example 16 except that the coating layer (4) was removed.

The results of examining the characteristics of the tapes on each side are shown in the table below.

In this way, in this example, the friction coefficient of the tape is reduced and running stability is obtained.

[Brief explanation of the drawing]

1 to 5 are cross-sectional views showing embodiments of magnetic recording media according to the present invention. +11 is the base, (2) is the magnetic layer, (3) is the top coat, +41 +61 is the coating layer, and (5) is the back coat layer. 7

Claims (1)

[Claims] In a magnetic recording medium having a magnetic layer on a support, the magnetic recording medium has a general formula (where X is 10COR', -R20COR3, -R
4COOR5 or 186GOOR, R1, R3
, R5 is a saturated or unsaturated monovalent hydrocarbon group having 7 to 21 carbon atoms, R2 and R4 are saturated or unsaturated divalent hydrocarbon groups having 1 to 21 carbon atoms, and R6 is a saturated hydrocarbon group having 7 to 21 carbon atoms. 2
It is a valence hydrocarbon group. A1 and A2 are -CI+3, 0
(CTo), +(CF2)j1 selected from Y or X
, l is 0, ■ or 2, j is an integer from 1 to 12,
Y is a hydrogen atom or a monoatomic atom. l, m and n are all integers from O to 300, and if A1 or A2 is X! -〇, m=o is also acceptable, and A1 or A2 is -O
(CH2) Ic JF 2J++ is 7! -0,
n = 0 is also possible, At and A2 are both 10) + 3, then 2
= 0, but both m and n must not be 0. ) A magnetic recording medium comprising an organopolysiloxane compound represented by: